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br-parser-tools/br-parser-tools-doc/LICENSE.txt
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parser-tools-doc
Copyright (c) 2010-2014 PLT Design Inc.
This package is distributed under the GNU Lesser General Public
License (LGPL). This means that you can link this package into proprietary
applications, provided you follow the rules stated in the LGPL. You
can also modify this package; if you distribute a modified version,
you must distribute it under the terms of the LGPL, which in
particular means that you must release the source code for the
modified software. See http://www.gnu.org/copyleft/lesser.html
for more information.

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br-parser-tools/br-parser-tools-doc/br-parser-tools/br-parser-tools.scrbl
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#lang scribble/doc
@(require scribble/manual scribble/struct scribble/xref scribble/bnf
(for-label scheme/base
scheme/contract
br-parser-tools/lex
(prefix-in : br-parser-tools/lex-sre)
br-parser-tools/yacc
br-parser-tools/cfg-parser))
@title{Parser Tools: @exec{lex} and @exec{yacc}-style Parsing (Beautiful Racket edition)}
@author["Scott Owens (99%)" "Matthew Butterick (1%)"]
This documentation assumes familiarity with @exec{lex} and @exec{yacc}
style lexer and parser generators.
@table-of-contents[]
@; ----------------------------------------------------------------------
@section{Lexers}
@section-index["lex"]
@section-index["scanning"]
@section-index["scanner"]
@defmodule[br-parser-tools/lex]
@; ----------------------------------------
@subsection{Creating a Lexer}
@defform/subs[#:literals (repetition union intersection complement concatenation
char-range char-complement
eof special special-comment)
(lexer [trigger action-expr] ...)
([trigger re
(eof)
(special)
(special-comment)]
[re id
string
character
(repetition lo hi re)
(union re ...)
(intersection re ...)
(complement re)
(concatenation re ...)
(char-range char char)
(char-complement re)
(id datum ...)])]{
Produces a function that takes an input-port, matches the
@racket[re] patterns against the buffer, and returns the result of
executing the corresponding @racket[action-expr]. When multiple
patterns match, a lexer will choose the longest match, breaking
ties in favor of the rule appearing first.
@margin-note{The implementation of @racketmodname[syntax-color/racket-lexer]
contains a lexer for the @racketmodname[racket] language.
In addition, files in the @filepath{examples} sub-directory
of the @filepath{br-parser-tools} collection contain
simpler example lexers.}
An @racket[re] is matched as follows:
@itemize[
@item{@racket[id] --- expands to the named @deftech{lexer abbreviation};
abbreviations are defined via @racket[define-lex-abbrev] or supplied by modules
like @racketmodname[br-parser-tools/lex-sre].}
@item{@racket[string] --- matches the sequence of characters in @racket[string].}
@item{@racket[character] --- matches a literal @racket[character].}
@item{@racket[(repetition lo hi re)] --- matches @racket[re] repeated between @racket[lo]
and @racket[hi] times, inclusive; @racket[hi] can be @racket[+inf.0] for unbounded repetitions.}
@item{@racket[(union re ...)] --- matches if any of the sub-expressions match}
@item{@racket[(intersection re ...)] --- matches if all of the @racket[re]s match.}
@item{@racket[(complement re)] --- matches anything that @racket[re] does not.}
@item{@racket[(concatenation re ...)] --- matches each @racket[re] in succession.}
@item{@racket[(char-range char char)] --- matches any character between the two (inclusive);
a single character string can be used as a @racket[char].}
@item{@racket[(char-complement re)] --- matches any character not matched by @racket[re].
The sub-expression must be a set of characters @racket[re].}
@item{@racket[(id datum ...)] --- expands the @deftech{lexer macro} named @racket[id]; macros
are defined via @racket[define-lex-trans].}
]
Note that both @racket[(concatenation)] and @racket[""] match the
empty string, @racket[(union)] matches nothing,
@racket[(intersection)] matches any string, and
@racket[(char-complement (union))] matches any single character.
The regular expression language is not designed to be used directly,
but rather as a basis for a user-friendly notation written with
regular expression macros. For example,
@racketmodname[br-parser-tools/lex-sre] supplies operators from Olin
Shivers's SREs, and @racketmodname[br-parser-tools/lex-plt-v200] supplies
(deprecated) operators from the previous version of this library.
Since those libraries provide operators whose names match other Racket
bindings, such as @racket[*] and @racket[+], they normally must be
imported using a prefix:
@racketblock[
(require (prefix-in : br-parser-tools/lex-sre))
]
The suggested prefix is @racket[:], so that @racket[:*] and
@racket[:+] are imported. Of course, a prefix other than @racket[:]
(such as @racket[re-]) will work too.
Since negation is not a common operator on regular expressions, here
are a few examples, using @racket[:] prefixed SRE syntax:
@itemize[
@item{@racketblock0[(complement "1")]
Matches all strings except the string @racket["1"], including
@racket["11"], @racket["111"], @racket["0"], @racket["01"],
@racket[""], and so on.}
@item{@racketblock0[(complement (:* "1"))]
Matches all strings that are not sequences of @racket["1"],
including @racket["0"], @racket["00"], @racket["11110"],
@racket["0111"], @racket["11001010"] and so on.}
@item{@racketblock0[(:& (:: any-string "111" any-string)
(complement (:or (:: any-string "01") (:+ "1"))))]
Matches all strings that have 3 consecutive ones, but not those that
end in @racket["01"] and not those that are ones only. These
include @racket["1110"], @racket["0001000111"] and @racket["0111"]
but not @racket[""], @racket["11"], @racket["11101"], @racket["111"]
and @racket["11111"].}
@item{@racketblock0[(:: "/*" (complement (:: any-string "*/" any-string)) "*/")]
Matches Java/C block comments. @racket["/**/"],
@racket["/******/"], @racket["/*////*/"], @racket["/*asg4*/"] and so
on. It does not match @racket["/**/*/"], @racket["/* */ */"] and so
on. @racket[(:: any-string "*/" any-string)] matches any string
that has a @racket["*/"] in is, so @racket[(complement (:: any-string "*/"
any-string))] matches any string without a @racket["*/"] in it.}
@item{@racketblock0[(:: "/*" (:* (complement "*/")) "*/")]
Matches any string that starts with @racket["/*"] and ends with
@racket["*/"], including @racket["/* */ */ */"].
@racket[(complement "*/")] matches any string except @racket["*/"].
This includes @racket["*"] and @racket["/"] separately. Thus
@racket[(:* (complement "*/"))] matches @racket["*/"] by first
matching @racket["*"] and then matching @racket["/"]. Any other
string is matched directly by @racket[(complement "*/")]. In other
words, @racket[(:* (complement "xx"))] = @racket[any-string]. It is
usually not correct to place a @racket[:*] around a
@racket[complement].}
]
The following binding have special meaning inside of a lexer
action:
@itemize[
@item{@racket[start-pos] --- a @racket[position] struct for the first character matched.}
@item{@racket[end-pos] --- a @racket[position] struct for the character after the last character in the match.}
@item{@racket[lexeme] --- the matched string.}
@item{@racket[input-port] --- the input-port being
processed (this is useful for matching input with multiple
lexers).}
@item{@racket[(return-without-pos x)] and @racket[(return-without-srcloc x)] are functions (continuations) that
immediately return the value of @racket[x] from the lexer. This useful
in a src-pos or src-loc lexer to prevent the lexer from adding source
information. For example:
@racketblock[
(define get-token
(lexer-srcloc
...
((comment) (get-token input-port))
...))
]
would wrap the source location information for the comment around
the value of the recursive call. Using
@racket[((comment) (return-without-srcloc (get-token input-port)))]
will cause the value of the recursive call to be returned without
wrapping position around it.}
]
The lexer raises an @racket[exn:fail:read] exception if none of the
regular expressions match the input. Hint: If @racket[(any-char
_custom-error-behavior)] is the last rule, then there will always
be a match, and @racket[_custom-error-behavior] is executed to
handle the error situation as desired, only consuming the first
character from the input buffer.
In addition to returning characters, input
ports can return @racket[eof-object]s. Custom input ports can
also return a @racket[special-comment] value to indicate a
non-textual comment, or return another arbitrary value (a
special). The non-@racket[re] @racket[trigger] forms handle these
cases:
@itemize[
@item{The @racket[(eof)] rule is matched when the input port
returns an @racket[eof-object] value. If no @racket[(eof)]
rule is present, the lexer returns the symbol @racket['eof]
when the port returns an @racket[eof-object] value.}
@item{The @racket[(special-comment)] rule is matched when the
input port returns a @racket[special-comment] structure. If no
@racket[special-comment] rule is present, the lexer
automatically tries to return the next token from the input
port.}
@item{The @racket[(special)] rule is matched when the input
port returns a value other than a character,
@racket[eof-object], or @racket[special-comment] structure. If
no @racket[(special)] rule is present, the lexer returns
@racket[(void)].}]
End-of-files, specials, special-comments and special-errors cannot
be parsed via a rule using an ordinary regular expression
(but dropping down and manipulating the port to handle them
is possible in some situations).
Since the lexer gets its source information from the port, use
@racket[port-count-lines!] to enable the tracking of line and
column information. Otherwise, the line and column information
will return @racket[#f].
When peeking from the input port raises an exception (such as by
an embedded XML editor with malformed syntax), the exception can
be raised before all tokens preceding the exception have been
returned.
Each time the racket code for a lexer is compiled (e.g. when a
@filepath{.rkt} file containing a @racket[lexer] form is loaded),
the lexer generator is run. To avoid this overhead place the
lexer into a module and compile the module to a @filepath{.zo}
bytecode file.}
@defform[(lexer-src-pos (trigger action-expr) ...)]{
Like @racket[lexer], but for each @racket[_action-result] produced by
an @racket[action-expr], returns @racket[(make-position-token
_action-result start-pos end-pos)] instead of simply
@racket[_action-result].}
@defform[(lexer-srcloc (trigger action-expr) ...)]{
Like @racket[lexer], but for each @racket[_action-result] produced by
an @racket[action-expr], returns @racket[(make-srcloc-token
_action-result lexeme-srcloc)] instead of simply
@racket[_action-result].}
@deftogether[(
@defidform[start-pos]
@defidform[end-pos]
@defidform[lexeme]
@defidform[lexeme-srcloc]
@defidform[input-port]
@defidform[return-without-pos]
@defidform[return-without-srcloc]
)]{
Use of these names outside of a @racket[lexer] action is a syntax
error.}
@defstruct[position ([offset exact-positive-integer?]
[line exact-positive-integer?]
[col exact-nonnegative-integer?])]{
Instances of @racket[position] are bound to @racket[start-pos] and
@racket[end-pos]. The @racket[offset] field contains the offset of
the character in the input. The @racket[line] field contains the
line number of the character. The @racket[col] field contains the
offset in the current line.}
@defstruct[position-token ([token any/c]
[start-pos position?]
[end-pos position?])]{
Lexers created with @racket[lexer-src-pos] return instances of @racket[position-token].}
@defstruct[srcloc-token ([token any/c]
[srcloc srcloc?])]{
Lexers created with @racket[lexer-srcloc] return instances of @racket[srcloc-token].}
@defparam[file-path source any/c]{
A parameter that the lexer uses as the source location if it
raises a @racket[exn:fail:read] error. Setting this parameter allows
DrRacket, for example, to open the file containing the error.}
@defparam[lexer-file-path source any/c]{
Alias for @racket[file-path].}
@; ----------------------------------------
@subsection{Lexer Abbreviations and Macros}
@defform[(char-set string)]{
A @tech{lexer macro} that matches any character in @racket[string].}
@defidform[any-char]{A @tech{lexer abbreviation} that matches any character.}
@defidform[any-string]{A @tech{lexer abbreviation} that matches any string.}
@defidform[nothing]{A @tech{lexer abbreviation} that matches no string.}
@deftogether[(
@defidform[alphabetic]
@defidform[lower-case]
@defidform[upper-case]
@defidform[title-case]
@defidform[numeric]
@defidform[symbolic]
@defidform[punctuation]
@defidform[graphic]
@defidform[whitespace]
@defidform[blank]
@defidform[iso-control]
)]{
@tech{Lexer abbreviations} that match @racket[char-alphabetic?]
characters, @racket[char-lower-case?] characters, etc.}
@defform[(define-lex-abbrev id re)]{
Defines a @tech{lexer abbreviation} by associating a regular
expression to be used in place of the @racket[id] in other
regular expression. The definition of name has the same scoping
properties as a other syntactic binding (e.g., it can be exported
from a module).}
@defform[(define-lex-abbrevs (id re) ...)]{
Like @racket[define-lex-abbrev], but defines several @tech{lexer
abbreviations}.}
@defform[(define-lex-trans id trans-expr)]{
Defines a @tech{lexer macro}, where @racket[trans-expr] produces a
transformer procedure that takes one argument. When @racket[(id
_datum ...)] appears as a regular expression, it is replaced with
the result of applying the transformer to the expression.}
@; ----------------------------------------
@subsection{Lexer SRE Operators}
@defmodule[br-parser-tools/lex-sre]
@; Put the docs in a macro, so that we can bound the scope of
@; the import of `*', etc.:
@(define-syntax-rule (lex-sre-doc)
(...
(begin
(require (for-label br-parser-tools/lex-sre))
@defform[(* re ...)]{
Repetition of @racket[re] sequence 0 or more times.}
@defform[(+ re ...)]{
Repetition of @racket[re] sequence 1 or more times.}
@defform[(? re ...)]{
Zero or one occurrence of @racket[re] sequence.}
@defform[(= n re ...)]{
Exactly @racket[n] occurrences of @racket[re] sequence, where
@racket[n] must be a literal exact, non-negative number.}
@defform[(>= n re ...)]{
At least @racket[n] occurrences of @racket[re] sequence, where
@racket[n] must be a literal exact, non-negative number.}
@defform[(** n m re ...)]{
Between @racket[n] and @racket[m] (inclusive) occurrences of
@racket[re] sequence, where @racket[n] must be a literal exact,
non-negative number, and @racket[m] must be literally either
@racket[#f], @racket[+inf.0], or an exact, non-negative number; a
@racket[#f] value for @racket[m] is the same as @racket[+inf.0].}
@defform[(or re ...)]{
Same as @racket[(union re ...)].}
@deftogether[(
@defform[(: re ...)]
@defform[(seq re ...)]
)]{
Both forms concatenate the @racket[re]s.}
@defform[(& re ...)]{
Intersects the @racket[re]s.}
@defform[(- re ...)]{
The set difference of the @racket[re]s.}
@defform[(~ re ...)]{
Character-set complement, which each @racket[re] must match exactly
one character.}
@defform[(/ char-or-string ...)]{
Character ranges, matching characters between successive pairs of
characters.}
)))
@(lex-sre-doc)
@; ----------------------------------------
@subsection{Lexer Legacy Operators}
@defmodule[br-parser-tools/lex-plt-v200]
@(define-syntax-rule (lex-v200-doc)
(...
(begin
(require (for-label br-parser-tools/lex-plt-v200))
@t{The @racketmodname[br-parser-tools/lex-plt-v200] module re-exports
@racket[*], @racket[+], @racket[?], and @racket[&] from
@racketmodname[br-parser-tools/lex-sre]. It also re-exports
@racket[:or] as @racket[:], @racket[::] as @racket[|@|], @racket[:~]
as @racket[^], and @racket[:/] as @racket[-].}
@defform[(epsilon)]{
A @tech{lexer macro} that matches an empty sequence.}
@defform[(~ re ...)]{
The same as @racket[(complement re ...)].})))
@(lex-v200-doc)
@; ----------------------------------------
@subsection{Tokens}
Each @racket[_action-expr] in a @racket[lexer] form can produce any
kind of value, but for many purposes, producing a @deftech{token}
value is useful. Tokens are usually necessary for inter-operating with
a parser generated by @racket[br-parser-tools/parser], but tokens may not
be the right choice when using @racket[lexer] in other situations.
@defform[(define-tokens group-id (token-id ...))]{
Binds @racket[group-id] to the group of tokens being defined. For
each @racket[token-id], a function
@racketidfont{token-}@racket[token-id] is created that takes any
value and puts it in a token record specific to @racket[token-id].
The token value is inspected using @racket[token-id] and
@racket[token-value].
A token cannot be named @racketidfont{error}, since
@racketidfont{error} it has special use in the parser.}
@defform[(define-empty-tokens group-id (token-id ...) )]{
Like @racket[define-tokens], except a each token constructor
@racketidfont{token-}@racket[token-id] takes no arguments and returns
@racket[(@#,racket[quote] token-id)].}
@defproc[(token-name [t (or/c token? symbol?)]) symbol?]{
Returns the name of a token that is represented either by a symbol
or a token structure.}
@defproc[(token-value [t (or/c token? symbol?)]) any/c]{
Returns the value of a token that is represented either by a symbol
or a token structure, returning @racket[#f] for a symbol token.}
@defproc[(token? [v any/c]) boolean?]{
Returns @racket[#t] if @racket[val] is a
token structure, @racket[#f] otherwise.}
@; ----------------------------------------------------------------------
@section{LALR(1) Parsers}
@section-index["yacc"]
@defmodule[br-parser-tools/yacc]
@defform/subs[#:literals (grammar tokens start end precs src-pos
suppress debug yacc-output prec)
(parser clause ...)
([clause (grammar (non-terminal-id
((grammar-id ...) maybe-prec expr)
...)
...)
(tokens group-id ...)
(start non-terminal-id ...)
(end token-id ...)
(@#,racketidfont{error} expr)
(precs (assoc token-id ...) ...)
(src-pos)
(suppress)
(debug filename)
(yacc-output filename)]
[maybe-prec code:blank
(prec token-id)]
[assoc left right nonassoc])]{
Creates a parser. The clauses may be in any order, as long as there
are no duplicates and all non-@italic{OPTIONAL} declarations are
present:
@itemize[
@item{@racketblock0[(grammar (non-terminal-id
((grammar-id ...) maybe-prec expr)
...)
...)]
Declares the grammar to be parsed. Each @racket[grammar-id] can
be a @racket[token-id] from a @racket[group-id] named in a
@racket[tokens] declaration, or it can be a
@racket[non-terminal-id] declared in the @racket[grammar]
declaration. The optional @racket[prec] declaration works with
the @racket[precs] declaration. The @racket[expr] is a
``semantic action,'' which is evaluated when the input is found
to match its corresponding production.
Each action is Racket code that has the same scope as its
parser's definition, except that the variables @racket[$1], ...,
@racketidfont{$}@math{i} are bound, where @math{i} is the number
of @racket[grammar-id]s in the corresponding production. Each
@racketidfont{$}@math{k} is bound to the result of the action
for the @math{k}@superscript{th} grammar symbol on the right of
the production, if that grammar symbol is a non-terminal, or the
value stored in the token if the grammar symbol is a terminal.
If the @racket[src-pos] option is present in the parser, then
variables @racket[$1-start-pos], ...,
@racketidfont{$}@math{i}@racketidfont{-start-pos} and
@racket[$1-end-pos], ...,
@racketidfont{$}@math{i}@racketidfont{-end-pos} and are also
available, and they refer to the position structures
corresponding to the start and end of the corresponding
@racket[grammar-symbol]. Grammar symbols defined as empty-tokens
have no @racketidfont{$}@math{k} associated, but do have
@racketidfont{$}@math{k}@racketidfont{-start-pos} and
@racketidfont{$}@math{k}@racketidfont{-end-pos}.
Also @racketidfont{$n-start-pos} and @racketidfont{$n-end-pos}
are bound to the largest start and end positions, (i.e.,
@racketidfont{$}@math{i}@racketidfont{-start-pos} and
@racketidfont{$}@math{i}@racketidfont{-end-pos}).
An @deftech{error production} can be defined by providing
a production of the form @racket[(error α)], where α is a
string of grammar symbols, possibly empty.
All of the productions for a given non-terminal must be grouped
with it. That is, no @racket[non-terminal-id] may appear twice
on the left hand side in a parser.}
@item{@racket[(tokens group-id ...)]
Declares that all of the tokens defined in each
@racket[group-id]---as bound by @racket[define-tokens] or
@racket[define-empty-tokens]---can be used by the parser in the
@racket[grammar] declaration.}
@item{@racket[(start non-terminal-id ...)]
Declares a list of starting non-terminals for the grammar.}
@item{@racket[(end token-id ...)]
Specifies a set of tokens from which some member must follow any
valid parse. For example, an EOF token would be specified for a
parser that parses entire files and a newline token for a parser
that parses entire lines individually.}
@item{@racket[(@#,racketidfont{error} expr)]
The @racket[expr] should evaluate to a function which will be
executed for its side-effect whenever the parser encounters an
error.
If the @racket[src-pos] declaration is present, the function
should accept 5 arguments,:
@racketblock[(lambda (tok-ok? tok-name tok-value _start-pos _end-pos)
....)]
Otherwise it should accept 3:
@racketblock[(lambda (tok-ok? tok-name tok-value)
....)]
The first argument will be @racket[#f] if and only if the error
is that an invalid token was received. The second and third
arguments will be the name and the value of the token at which
the error was detected. The fourth and fifth arguments, if
present, provide the source positions of that token.}
@item{@racket[(precs (assoc token-id ...) ...)]
@italic{OPTIONAL}
Precedence declarations to resolve shift/reduce and
reduce/reduce conflicts as in @exec{yacc}/@exec{bison}. An
@racket[assoc] must be one of @racket[left], @racket[right] or
@racket[nonassoc]. States with multiple shift/reduce or
reduce/reduce conflicts (or some combination thereof) are not
resolved with precedence.}
@item{@racket[(src-pos)] @italic{OPTIONAL}
Causes the generated parser to expect input in the form
@racket[(make-position-token _token _start-pos _end-pos)] instead
of simply @racket[_token]. Include this option when using the
parser with a lexer generated with @racket[lexer-src-pos].}
@item{@racket[(debug filename)] @italic{OPTIONAL}
Causes the parser generator to write the LALR table to the file
named @racket[filename] (unless the file exists), where
@racket[filename] is a literal string. Additionally, if a debug
file is specified, when a running generated parser encounters a
parse error on some input file, after the user specified error
expression returns, the complete parse stack is printed to
assist in debugging the grammar of that particular parser. The
numbers in the stack printout correspond to the state numbers in
the LALR table file.}
@item{@racket[(yacc-output filename)] @italic{OPTIONAL}
Causes the parser generator to write a grammar file in
approximately the syntax of @exec{yacc}/@exec{bison}. The file
might not be a valid @exec{yacc} file, because the Racket
grammar can use symbols that are invalid in C.}
@item{@racket[(suppress)] @italic{OPTIONAL}
Causes the parser generator not to report shift/reduce or
reduce/reduce conflicts.}
]
The result of a @racket[parser] expression with one @racket[start]
non-terminal is a function, @racket[_parse], that takes one
argument. This argument must be a zero argument function,
@racket[_gen], that produces successive tokens of the input each
time it is called. If desired, the @racket[_gen] may return
symbols instead of tokens, and the parser will treat symbols as
tokens of the corresponding name (with @racket[#f] as a value, so
it is usual to return symbols only in the case of empty tokens).
The @racket[_parse] function returns the value associated with the
parse tree by the semantic actions. If the parser encounters an
error, after invoking the supplied error function, it will try to
use @tech{error production}s to continue parsing. If it cannot, it
raises @racket[exn:fail:read].
If multiple non-terminals are provided in @racket[start], the
@racket[parser] expression produces a list of parsing functions,
one for each non-terminal in the same order. Each parsing function
is like the result of a parser expression with only one
@racket[start] non-terminal,
Each time the Racket code for a @racket[parser] is compiled
(e.g. when a @filepath{.rkt} file containing a @racket[parser] form
is loaded), the parser generator is run. To avoid this overhead
place the parser into a module and compile the module to a
@filepath{.zo} bytecode file.}
@section{Context-Free Parsers}
@section-index["cfg-parser"]
@defmodule[br-parser-tools/cfg-parser]{The @racketmodname[br-parser-tools/cfg-parser]
library provides a parser generator that is an alternative to that of
@racketmodname[br-parser-tools/yacc].}
@defform/subs[#:literals (grammar tokens start end precs src-pos
suppress debug yacc-output prec)
(cfg-parser clause ...)
([clause (grammar (non-terminal-id
((grammar-id ...) maybe-prec expr)
...)
...)
(tokens group-id ...)
(start non-terminal-id ...)
(end token-id ...)
(@#,racketidfont{error} expr)
(src-pos)])]{
Creates a parser similar to that of @racket[parser]. Unlike @racket[parser],
@racket[cfg-parser], can consume arbitrary and potentially ambiguous context-free
grammars. Its interface is a subset of @racketmodname[br-parser-tools/yacc], with
the following differences:
@itemize[
@item{@racket[(start non-terminal-id)]
Unlike @racket[parser], @racket[cfg-parser] only allows for
a single non-terminal-id.}
@item{The @racket[cfg-parser] form does not support the @racket[precs],
@racket[suppress], @racket[debug], or @racket[yacc-output]
options of @racket[parser].}
]
}
@; ----------------------------------------------------------------------
@section{Converting @exec{yacc} or @exec{bison} Grammars}
@defmodule[br-parser-tools/yacc-to-scheme]
@defproc[(trans [file path-string?]) any/c]{
Reads a C @exec{yacc}/@exec{bison} grammar from @racket[file] and
produces an s-expression that represents a Racket parser for use with
@racket[parser].
This function is intended to assist in the manual conversion of
grammars for use with @racket[parser], and not as a fully automatic
conversion tool. It is not entirely robust. For example, if the C
actions in the original grammar have nested blocks, the tool will fail.
Annotated examples are in the @filepath{examples} subdirectory of the
@filepath{br-parser-tools} collection.}
@; ----------------------------------------------------------------------
@index-section[]

3
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#lang info
(define scribblings '(("br-parser-tools.scrbl" (multi-page) (parsing-library))))

14
br-parser-tools/br-parser-tools-doc/info.rkt
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#lang info
(define collection 'multi)
(define deps '("base"))
(define build-deps '("scheme-lib"
"racket-doc"
"syntax-color-doc"
"br-parser-tools-lib"
"scribble-lib"))
(define update-implies '("br-parser-tools-lib"))
(define pkg-desc "documentation part of \"br-parser-tools\"")
(define pkg-authors '(mflatt))

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br-parser-tools/br-parser-tools-lib/LICENSE.txt
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parser-tools-lib
Copyright (c) 2010-2014 PLT Design Inc.
This package is distributed under the GNU Lesser General Public
License (LGPL). This means that you can link this package into proprietary
applications, provided you follow the rules stated in the LGPL. You
can also modify this package; if you distribute a modified version,
you must distribute it under the terms of the LGPL, which in
particular means that you must release the source code for the
modified software. See http://www.gnu.org/copyleft/lesser.html
for more information.

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#lang racket/base
;; This module implements a parser form like the br-parser-tools's
;; `parser', except that it works on an arbitrary CFG (returning
;; the first sucecssful parse).
;; I'm pretty sure that this is an implementation of Earley's
;; algorithm.
;; To a first approximation, it's a backtracking parser. Alternative
;; for a non-terminal are computed in parallel, and multiple attempts
;; to compute the same result block until the first one completes. If
;; you get into deadlock, such as when trying to match
;; <foo> := <foo>
;; then it means that there's no successful parse, so everything
;; that's blocked fails.
;; A cache holds the series of results for a particular non-terminal
;; at a particular starting location. (A series is used, instead of a
;; sinlge result, for backtracking.) Otherwise, the parser uses
;; backtracking search. Backtracking is implemented through explicit
;; success and failure continuations. Multiple results for a
;; particular nonterminal and location are kept only when they have
;; different lengths. (Otherwise, in the spirit of finding one
;; successful parse, only the first result is kept.)
;; The br-parser-tools's `parse' is used to transform tokens in the
;; grammar to tokens specific to this parser. In other words, this
;; parser uses `parser' so that it doesn't have to know anything about
;; tokens.
;;
(require br-parser-tools/yacc
br-parser-tools/lex)
(require (for-syntax racket/base
syntax/boundmap
br-parser-tools/private-lex/token-syntax))
(provide cfg-parser)
;; A raw token, wrapped so that we can recognize it:
(define-struct tok (name orig-name val start end))
;; Represents the thread scheduler:
(define-struct tasks (active active-back waits multi-waits cache progress?))
(define-for-syntax make-token-identifier-mapping make-hasheq)
(define-for-syntax token-identifier-mapping-get
(case-lambda
[(t tok)
(hash-ref t (syntax-e tok))]
[(t tok fail)
(hash-ref t (syntax-e tok) fail)]))
(define-for-syntax token-identifier-mapping-put!
(lambda (t tok v)
(hash-set! t (syntax-e tok) v)))
(define-for-syntax token-identifier-mapping-map
(lambda (t f)
(hash-map t f)))
;; Used to calculate information on the grammar, such as whether
;; a particular non-terminal is "simple" instead of recursively defined.
(define-for-syntax (nt-fixpoint nts proc nt-ids patss)
(define (ormap-all val f as bs)
(cond
[(null? as) val]
[else (ormap-all (or (f (car as) (car bs)) val)
f
(cdr as) (cdr bs))]))
(let loop ()
(when (ormap-all #f
(lambda (nt pats)
(let ([old (bound-identifier-mapping-get nts nt)])
(let ([new (proc nt pats old)])
(if (equal? old new)
#f
(begin
(bound-identifier-mapping-put! nts nt new)
#t)))))
nt-ids patss)
(loop))))
;; Tries parse-a followed by parse-b. If parse-a is not simple,
;; then after parse-a succeeds once, we parallelize parse-b
;; and trying a second result for parse-a.
(define (parse-and simple-a? parse-a parse-b
stream last-consumed-token depth end success-k fail-k
max-depth tasks)
(letrec ([mk-got-k
(lambda (success-k fail-k)
(lambda (val stream last-consumed-token depth max-depth tasks next1-k)
(if simple-a?
(parse-b val stream last-consumed-token depth end
(mk-got2-k success-k fail-k next1-k)
(mk-fail2-k success-k fail-k next1-k)
max-depth tasks)
(parallel-or
(lambda (success-k fail-k max-depth tasks)
(parse-b val stream last-consumed-token depth end
success-k fail-k
max-depth tasks))
(lambda (success-k fail-k max-depth tasks)
(next1-k (mk-got-k success-k fail-k)
fail-k max-depth tasks))
success-k fail-k max-depth tasks))))]
[mk-got2-k
(lambda (success-k fail-k next1-k)
(lambda (val stream last-consumed-token depth max-depth tasks next-k)
(success-k val stream last-consumed-token depth max-depth tasks
(lambda (success-k fail-k max-depth tasks)
(next-k (mk-got2-k success-k fail-k next1-k)
(mk-fail2-k success-k fail-k next1-k)
max-depth tasks)))))]
[mk-fail2-k
(lambda (success-k fail-k next1-k)
(lambda (max-depth tasks)
(next1-k (mk-got-k success-k fail-k)
fail-k
max-depth
tasks)))])
(parse-a stream last-consumed-token depth end
(mk-got-k success-k fail-k)
fail-k
max-depth tasks)))
;; Parallel or for non-terminal alternatives
(define (parse-parallel-or parse-a parse-b stream last-consumed-token depth end success-k fail-k max-depth tasks)
(parallel-or (lambda (success-k fail-k max-depth tasks)
(parse-a stream last-consumed-token depth end success-k fail-k max-depth tasks))
(lambda (success-k fail-k max-depth tasks)
(parse-b stream last-consumed-token depth end success-k fail-k max-depth tasks))
success-k fail-k max-depth tasks))
;; Generic parallel-or
(define (parallel-or parse-a parse-b success-k fail-k max-depth tasks)
(define answer-key (gensym))
(letrec ([gota-k
(lambda (val stream last-consumed-token depth max-depth tasks next-k)
(report-answer answer-key
max-depth
tasks
(list val stream last-consumed-token depth next-k)))]
[faila-k
(lambda (max-depth tasks)
(report-answer answer-key
max-depth
tasks
null))])
(let* ([tasks (queue-task
tasks
(lambda (max-depth tasks)
(parse-a gota-k
faila-k
max-depth tasks)))]
[tasks (queue-task
tasks
(lambda (max-depth tasks)
(parse-b gota-k
faila-k
max-depth tasks)))]
[queue-next (lambda (next-k tasks)
(queue-task tasks
(lambda (max-depth tasks)
(next-k gota-k
faila-k
max-depth tasks))))])
(letrec ([mk-got-one
(lambda (immediate-next? get-nth success-k)
(lambda (val stream last-consumed-token depth max-depth tasks next-k)
(let ([tasks (if immediate-next?
(queue-next next-k tasks)
tasks)])
(success-k val stream last-consumed-token depth max-depth
tasks
(lambda (success-k fail-k max-depth tasks)
(let ([tasks (if immediate-next?
tasks
(queue-next next-k tasks))])
(get-nth max-depth tasks success-k fail-k)))))))]
[get-first
(lambda (max-depth tasks success-k fail-k)
(wait-for-answer #f max-depth tasks answer-key
(mk-got-one #t get-first success-k)
(lambda (max-depth tasks)
(get-second max-depth tasks success-k fail-k))
#f))]
[get-second
(lambda (max-depth tasks success-k fail-k)
(wait-for-answer #f max-depth tasks answer-key
(mk-got-one #f get-second success-k)
fail-k #f))])
(get-first max-depth tasks success-k fail-k)))))
;; Non-terminal alternatives where the first is "simple" can be done
;; sequentially, which is simpler
(define (parse-or parse-a parse-b
stream last-consumed-token depth end success-k fail-k max-depth tasks)
(letrec ([mk-got-k
(lambda (success-k fail-k)
(lambda (val stream last-consumed-token depth max-depth tasks next-k)
(success-k val stream last-consumed-token depth
max-depth tasks
(lambda (success-k fail-k max-depth tasks)
(next-k (mk-got-k success-k fail-k)
(mk-fail-k success-k fail-k)
max-depth tasks)))))]
[mk-fail-k
(lambda (success-k fail-k)
(lambda (max-depth tasks)
(parse-b stream last-consumed-token depth end success-k fail-k max-depth tasks)))])
(parse-a stream last-consumed-token depth end
(mk-got-k success-k fail-k)
(mk-fail-k success-k fail-k)
max-depth tasks)))
;; Starts a thread
(define queue-task
(lambda (tasks t [progress? #t])
(make-tasks (tasks-active tasks)
(cons t (tasks-active-back tasks))
(tasks-waits tasks)
(tasks-multi-waits tasks)
(tasks-cache tasks)
(or progress? (tasks-progress? tasks)))))
;; Reports an answer to a waiting thread:
(define (report-answer answer-key max-depth tasks val)
(let ([v (hash-ref (tasks-waits tasks) answer-key (lambda () #f))])
(if v
(let ([tasks (make-tasks (cons (v val)
(tasks-active tasks))
(tasks-active-back tasks)
(tasks-waits tasks)
(tasks-multi-waits tasks)
(tasks-cache tasks)
#t)])
(hash-remove! (tasks-waits tasks) answer-key)
(swap-task max-depth tasks))
;; We have an answer ready too fast; wait
(swap-task max-depth
(queue-task tasks
(lambda (max-depth tasks)
(report-answer answer-key max-depth tasks val))
#f)))))
;; Reports an answer to multiple waiting threads:
(define (report-answer-all answer-key max-depth tasks val k)
(let ([v (hash-ref (tasks-multi-waits tasks) answer-key (lambda () null))])
(hash-remove! (tasks-multi-waits tasks) answer-key)
(let ([tasks (make-tasks (append (map (lambda (a) (a val)) v)
(tasks-active tasks))
(tasks-active-back tasks)
(tasks-waits tasks)
(tasks-multi-waits tasks)
(tasks-cache tasks)
#t)])
(k max-depth tasks))))
;; Waits for an answer; if `multi?' is #f, this is sole waiter, otherwise
;; there might be many. Use wither #t or #f (and `report-answer' or
;; `report-answer-all', resptively) consistently for a particular answer key.
(define (wait-for-answer multi? max-depth tasks answer-key success-k fail-k deadlock-k)
(let ([wait (lambda (val)
(lambda (max-depth tasks)
(if val
(if (null? val)
(fail-k max-depth tasks)
(let-values ([(val stream last-consumed-token depth next-k) (apply values val)])
(success-k val stream last-consumed-token depth max-depth tasks next-k)))
(deadlock-k max-depth tasks))))])
(if multi?
(hash-set! (tasks-multi-waits tasks) answer-key
(cons wait (hash-ref (tasks-multi-waits tasks) answer-key
(lambda () null))))
(hash-set! (tasks-waits tasks) answer-key wait))
(let ([tasks (make-tasks (tasks-active tasks)
(tasks-active-back tasks)
(tasks-waits tasks)
(tasks-multi-waits tasks)
(tasks-cache tasks)
#t)])
(swap-task max-depth tasks))))
;; Swap thread
(define (swap-task max-depth tasks)
;; Swap in first active:
(if (null? (tasks-active tasks))
(if (tasks-progress? tasks)
(swap-task max-depth
(make-tasks (reverse (tasks-active-back tasks))
null
(tasks-waits tasks)
(tasks-multi-waits tasks)
(tasks-cache tasks)
#f))
;; No progress, so issue failure for all multi-waits
(if (zero? (hash-count (tasks-multi-waits tasks)))
(error 'swap-task "Deadlock")
(swap-task max-depth
(make-tasks (apply
append
(hash-map (tasks-multi-waits tasks)
(lambda (k l)
(map (lambda (v) (v #f)) l))))
(tasks-active-back tasks)
(tasks-waits tasks)
(make-hasheq)
(tasks-cache tasks)
#t))))
(let ([t (car (tasks-active tasks))]
[tasks (make-tasks (cdr (tasks-active tasks))
(tasks-active-back tasks)
(tasks-waits tasks)
(tasks-multi-waits tasks)
(tasks-cache tasks)
(tasks-progress? tasks))])
(t max-depth tasks))))
;; Finds the symbolic representative of a token class
(define-for-syntax (map-token toks tok)
(car (token-identifier-mapping-get toks tok)))
(define no-pos-val (make-position #f #f #f))
(define-for-syntax no-pos
(let ([npv ((syntax-local-certifier) #'no-pos-val)])
(lambda (stx) npv)))
(define-for-syntax at-tok-pos
(lambda (sel expr)
(lambda (stx)
#`(let ([v #,expr]) (if v (#,sel v) no-pos-val)))))
;; Builds a matcher for a particular alternative
(define-for-syntax (build-match nts toks pat handle $ctx)
(let loop ([pat pat]
[pos 1])
(if (null? pat)
#`(success-k #,handle stream last-consumed-token depth max-depth tasks
(lambda (success-k fail-k max-depth tasks)
(fail-k max-depth tasks)))
(let ([id (datum->syntax (car pat)
(string->symbol (format "$~a" pos)))]
[id-start-pos (datum->syntax (car pat)
(string->symbol (format "$~a-start-pos" pos)))]
[id-end-pos (datum->syntax (car pat)
(string->symbol (format "$~a-end-pos" pos)))]
[n-end-pos (and (null? (cdr pat))
(datum->syntax (car pat) '$n-end-pos))])
(cond
[(bound-identifier-mapping-get nts (car pat) (lambda () #f))
;; Match non-termimal
#`(parse-and
;; First part is simple? (If so, we don't have to parallelize the `and'.)
#,(let ([l (bound-identifier-mapping-get nts (car pat) (lambda () #f))])
(or (not l)
(andmap values (caddr l))))
#,(car pat)
(let ([original-stream stream])
(lambda (#,id stream last-consumed-token depth end success-k fail-k max-depth tasks)
(let-syntax ([#,id-start-pos (at-tok-pos #'(if (eq? original-stream stream)
tok-end
tok-start)
#'(if (eq? original-stream stream)
last-consumed-token
(and (pair? original-stream)
(car original-stream))))]
[#,id-end-pos (at-tok-pos #'tok-end #'last-consumed-token)]
#,@(if n-end-pos
#`([#,n-end-pos (at-tok-pos #'tok-end #'last-consumed-token)])
null))
#,(loop (cdr pat) (add1 pos)))))
stream last-consumed-token depth
#,(let ([cnt (apply +
(map (lambda (item)
(cond
[(bound-identifier-mapping-get nts item (lambda () #f))
=> (lambda (l) (car l))]
[else 1]))
(cdr pat)))])
#`(- end #,cnt))
success-k fail-k max-depth tasks)]
[else
;; Match token
(let ([tok-id (map-token toks (car pat))])
#`(if (and (pair? stream)
(eq? '#,tok-id (tok-name (car stream))))
(let* ([stream-a (car stream)]
[#,id (tok-val stream-a)]
[last-consumed-token (car stream)]
[stream (cdr stream)]
[depth (add1 depth)])
(let ([max-depth (max max-depth depth)])
(let-syntax ([#,id-start-pos (at-tok-pos #'tok-start #'stream-a)]
[#,id-end-pos (at-tok-pos #'tok-end #'stream-a)]
#,@(if n-end-pos
#`([#,n-end-pos (at-tok-pos #'tok-end #'stream-a)])
null))
#,(loop (cdr pat) (add1 pos)))))
(fail-k max-depth tasks)))])))))
;; Starts parsing to match a non-terminal. There's a minor
;; optimization that checks for known starting tokens. Otherwise,
;; use the cache, block if someone else is already trying the match,
;; and cache the result if it's computed.
;; The cache maps nontermial+startingpos+iteration to a result, where
;; the iteration is 0 for the first match attempt, 1 for the second,
;; etc.
(define (parse-nt/share key min-cnt init-tokens stream last-consumed-token depth end max-depth tasks success-k fail-k k)
(if (and (positive? min-cnt)
(pair? stream)
(not (memq (tok-name (car stream)) init-tokens)))
;; No such leading token; give up
(fail-k max-depth tasks)
;; Run pattern
(let loop ([n 0]
[success-k success-k]
[fail-k fail-k]
[max-depth max-depth]
[tasks tasks]
[k k])
(let ([answer-key (gensym)]
[table-key (vector key depth n)]
[old-depth depth]
[old-stream stream])
#;(printf "Loop ~a\n" table-key)
(cond
[(hash-ref (tasks-cache tasks) table-key (lambda () #f))
=> (lambda (result)
#;(printf "Reuse ~a\n" table-key)
(result success-k fail-k max-depth tasks))]
[else
#;(printf "Try ~a ~a\n" table-key (map tok-name stream))
(hash-set! (tasks-cache tasks) table-key
(lambda (success-k fail-k max-depth tasks)
#;(printf "Wait ~a ~a\n" table-key answer-key)
(wait-for-answer #t max-depth tasks answer-key success-k fail-k
(lambda (max-depth tasks)
#;(printf "Deadlock ~a ~a\n" table-key answer-key)
(fail-k max-depth tasks)))))
(let result-loop ([max-depth max-depth][tasks tasks][k k])
(letrec ([orig-stream stream]
[new-got-k
(lambda (val stream last-consumed-token depth max-depth tasks next-k)
;; Check whether we already have a result that consumed the same amount:
(let ([result-key (vector #f key old-depth depth)])
(cond
[(hash-ref (tasks-cache tasks) result-key (lambda () #f))
;; Go for the next-result
(result-loop max-depth
tasks
(lambda (end max-depth tasks success-k fail-k)
(next-k success-k fail-k max-depth tasks)))]
[else
#;(printf "Success ~a ~a\n" table-key
(map tok-name (let loop ([d old-depth][s old-stream])
(if (= d depth)
null
(cons (car s) (loop (add1 d) (cdr s)))))))
(let ([next-k (lambda (success-k fail-k max-depth tasks)
(loop (add1 n)
success-k
fail-k
max-depth
tasks
(lambda (end max-depth tasks success-k fail-k)
(next-k success-k fail-k max-depth tasks))))])
(hash-set! (tasks-cache tasks) result-key #t)
(hash-set! (tasks-cache tasks) table-key
(lambda (success-k fail-k max-depth tasks)
(success-k val stream last-consumed-token depth max-depth tasks next-k)))
(report-answer-all answer-key
max-depth
tasks
(list val stream last-consumed-token depth next-k)
(lambda (max-depth tasks)
(success-k val stream last-consumed-token depth max-depth tasks next-k))))])))]
[new-fail-k
(lambda (max-depth tasks)
#;(printf "Failure ~a\n" table-key)
(hash-set! (tasks-cache tasks) table-key
(lambda (success-k fail-k max-depth tasks)
(fail-k max-depth tasks)))
(report-answer-all answer-key
max-depth
tasks
null
(lambda (max-depth tasks)
(fail-k max-depth tasks))))])
(k end max-depth tasks new-got-k new-fail-k)))])))))
;; These temp identifiers can't be `gensym` or `generate-temporary`
;; because they have to be consistent between module loads
;; (IIUC, the parser is multi-threaded, and this approach is not thread-safe)
;; so I see no alternative to the old standby of making them ludicrously unlikely
(define-for-syntax start-id-temp 'start_jihqolbbafscgxvsufnepvmxqipnxgmlpxukmdoqxqzmzgaogaftbkbyqjttwwfimifowdxfyekjiixdmtprfkcvfciraehoeuaz)
(define-for-syntax atok-id-temp 'atok_wrutdjgecmybyfipiwsgjlvsveryodlgassuzcargiuznzgdghrykfqfbwcjgzdhdoeqxcucmtjkuyucskzethozhqkasphdwbht)
(define-syntax (cfg-parser stx)
(syntax-case stx ()
[(_ clause ...)
(let ([clauses (syntax->list #'(clause ...))])
(let-values ([(start grammar cfg-error parser-clauses src-pos?)
(let ([all-toks (apply
append
(map (lambda (clause)
(syntax-case clause (tokens)
[(tokens t ...)
(apply
append
(map (lambda (t)
(let ([v (syntax-local-value t (lambda () #f))])
(cond
[(terminals-def? v)
(map (lambda (v)
(cons v #f))
(syntax->list (terminals-def-t v)))]
[(e-terminals-def? v)
(map (lambda (v)
(cons v #t))
(syntax->list (e-terminals-def-t v)))]
[else null])))
(syntax->list #'(t ...))))]
[_else null]))
clauses))]
[all-end-toks (apply
append
(map (lambda (clause)
(syntax-case clause (end)
[(end t ...)
(syntax->list #'(t ...))]
[_else null]))
clauses))])
(let loop ([clauses clauses]
[cfg-start #f]
[cfg-grammar #f]
[cfg-error #f]
[src-pos? #f]
[parser-clauses null])
(if (null? clauses)
(values cfg-start
cfg-grammar
cfg-error
(reverse parser-clauses)
src-pos?)
(syntax-case (car clauses) (start error grammar src-pos)
[(start tok)
(loop (cdr clauses) #'tok cfg-grammar cfg-error src-pos? parser-clauses)]
[(error expr)
(loop (cdr clauses) cfg-start cfg-grammar #'expr src-pos? parser-clauses)]
[(grammar [nt [pat handle0 handle ...] ...] ...)
(let ([nts (make-bound-identifier-mapping)]
[toks (make-token-identifier-mapping)]
[end-toks (make-token-identifier-mapping)]
[nt-ids (syntax->list #'(nt ...))]
[patss (map (lambda (stx)
(map syntax->list (syntax->list stx)))
(syntax->list #'((pat ...) ...)))])
(for-each (lambda (nt)
(bound-identifier-mapping-put! nts nt (list 0)))
nt-ids)
(for-each (lambda (t)
(token-identifier-mapping-put! end-toks t #t))
all-end-toks)
(for-each (lambda (t)
(unless (token-identifier-mapping-get end-toks (car t) (lambda () #f))
(let ([id (gensym (syntax-e (car t)))])
(token-identifier-mapping-put! toks (car t)
(cons id (cdr t))))))
all-toks)
;; Compute min max size for each non-term:
(nt-fixpoint
nts
(lambda (nt pats old-list)
(let ([new-cnt
(apply
min
(map (lambda (pat)
(apply
+
(map (lambda (elem)
(car
(bound-identifier-mapping-get nts
elem
(lambda () (list 1)))))
pat)))
pats))])
(if (new-cnt . > . (car old-list))
(cons new-cnt (cdr old-list))
old-list)))
nt-ids patss)
;; Compute set of toks that must appear at the beginning
;; for a non-terminal
(nt-fixpoint
nts
(lambda (nt pats old-list)
(let ([new-list
(apply
append
(map (lambda (pat)
(let loop ([pat pat])
(if (pair? pat)
(let ([l (bound-identifier-mapping-get
nts
(car pat)
(lambda ()
(list 1 (map-token toks (car pat)))))])
;; If the non-terminal can match 0 things,
;; then it might match something from the
;; next pattern element. Otherwise, it must
;; match the first element:
(if (zero? (car l))
(append (cdr l) (loop (cdr pat)))
(cdr l)))
null)))
pats))])
(let ([new (filter (lambda (id)
(andmap (lambda (id2)
(not (eq? id id2)))
(cdr old-list)))
new-list)])
(if (pair? new)
;; Drop dups in new list:
(let ([new (let loop ([new new])
(if (null? (cdr new))
new
(if (ormap (lambda (id)
(eq? (car new) id))
(cdr new))
(loop (cdr new))
(cons (car new) (loop (cdr new))))))])
(cons (car old-list) (append new (cdr old-list))))
old-list))))
nt-ids patss)
;; Determine left-recursive clauses:
(for-each (lambda (nt pats)
(let ([l (bound-identifier-mapping-get nts nt)])
(bound-identifier-mapping-put! nts nt (list (car l)
(cdr l)
(map (lambda (x) #f) pats)))))
nt-ids patss)
(nt-fixpoint
nts
(lambda (nt pats old-list)
(list (car old-list)
(cadr old-list)
(map (lambda (pat simple?)
(or simple?
(let ([l (map (lambda (elem)
(bound-identifier-mapping-get
nts
elem
(lambda () #f)))
pat)])
(andmap (lambda (i)
(or (not i)
(andmap values (caddr i))))
l))))
pats (caddr old-list))))
nt-ids patss)
;; Build a definition for each non-term:
(loop (cdr clauses)
cfg-start
(map (lambda (nt pats handles $ctxs)
(define info (bound-identifier-mapping-get nts nt))
(list nt
#`(let ([key (gensym '#,nt)])
(lambda (stream last-consumed-token depth end success-k fail-k max-depth tasks)
(parse-nt/share
key #,(car info) '#,(cadr info) stream last-consumed-token depth end
max-depth tasks
success-k fail-k
(lambda (end max-depth tasks success-k fail-k)
#,(let loop ([pats pats]
[handles (syntax->list handles)]
[$ctxs (syntax->list $ctxs)]
[simple?s (caddr info)])
(if (null? pats)
#'(fail-k max-depth tasks)
#`(#,(if (or (null? (cdr pats))
(car simple?s))
#'parse-or
#'parse-parallel-or)
(lambda (stream last-consumed-token depth end success-k fail-k max-depth tasks)
#,(build-match nts
toks
(car pats)
(car handles)
(car $ctxs)))
(lambda (stream last-consumed-token depth end success-k fail-k max-depth tasks)
#,(loop (cdr pats)
(cdr handles)
(cdr $ctxs)
(cdr simple?s)))
stream last-consumed-token depth end success-k fail-k max-depth tasks)))))))))
nt-ids
patss
(syntax->list #'(((begin handle0 handle ...) ...) ...))
(syntax->list #'((handle0 ...) ...)))
cfg-error
src-pos?
(list*
(with-syntax ([((tok tok-id . $e) ...)
(token-identifier-mapping-map toks
(lambda (k v)
(list* k
(car v)
(if (cdr v)
#f
'$1))))]
[(pos ...)
(if src-pos?
#'($1-start-pos $1-end-pos)
#'(#f #f))]
;; rename `start` and `atok` to temp ids
;; so that "start" and "atok" can be used as literal string tokens in a grammar.
;; not sure why this works, but it passes all tests.
[%start start-id-temp]
[%atok atok-id-temp])
#`(grammar (%start [() null]
[(%atok %start) (cons $1 $2)])
(%atok [(tok) (make-tok 'tok-id 'tok $e pos ...)] ...)))
(with-syntax ([%start start-id-temp])
#`(start %start))
parser-clauses)))]
[(grammar . _)
(raise-syntax-error
#f
"bad grammar clause"
stx
(car clauses))]
[(src-pos)
(loop (cdr clauses)
cfg-start
cfg-grammar
cfg-error
#t
(cons (car clauses) parser-clauses))]
[_else
(loop (cdr clauses)
cfg-start
cfg-grammar
cfg-error
src-pos?
(cons (car clauses) parser-clauses))]))))])
#`(let ([orig-parse (parser
[error (lambda (a b c)
(error 'cfg-parser "unexpected ~a token: ~a" b c))]
. #,parser-clauses)]
[error-proc #,cfg-error])
(letrec #,grammar
(lambda (get-tok)
(let ([tok-list (orig-parse get-tok)])
(letrec ([success-k
(lambda (val stream last-consumed-token depth max-depth tasks next)
(if (null? stream)
val
(next success-k fail-k max-depth tasks)))]
[fail-k (lambda (max-depth tasks)
(cond
[(null? tok-list)
(if error-proc
(error-proc #t
'no-tokens
#f
(make-position #f #f #f)
(make-position #f #f #f))
(error
'cfg-parse
"no tokens"))]
[else
(let ([bad-tok (list-ref tok-list
(min (sub1 (length tok-list))
max-depth))])
(if error-proc
(error-proc #t
(tok-orig-name bad-tok)
(tok-val bad-tok)
(tok-start bad-tok)
(tok-end bad-tok))
(error
'cfg-parse
"failed at ~a"
(tok-val bad-tok))))]))])
(#,start tok-list
;; we simulate a token at the very beginning with zero width
;; for use with the position-generating code (*-start-pos, *-end-pos).
(if (null? tok-list)
(tok #f #f #f
(position 1
#,(if src-pos? #'1 #'#f)
#,(if src-pos? #'0 #'#f))
(position 1
#,(if src-pos? #'1 #'#f)
#,(if src-pos? #'0 #'#f)))
(tok (tok-name (car tok-list))
(tok-orig-name (car tok-list))
(tok-val (car tok-list))
(tok-start (car tok-list))
(tok-start (car tok-list))))
0
(length tok-list)
success-k
fail-k
0
(make-tasks null null
(make-hasheq) (make-hasheq)
(make-hash) #t)))))))))]))
(module* test racket/base
(require (submod "..")
br-parser-tools/lex
racket/block
rackunit)
;; Test: parsing regular expressions.
;; Here is a test case on locations:
(block
(define-tokens regexp-tokens (ANCHOR STAR OR LIT LPAREN RPAREN EOF))
(define lex (lexer-src-pos ["|" (token-OR lexeme)]
["^" (token-ANCHOR lexeme)]
["*" (token-STAR lexeme)]
[(repetition 1 +inf.0 alphabetic) (token-LIT lexeme)]
["(" (token-LPAREN lexeme)]
[")" (token-RPAREN lexeme)]
[whitespace (return-without-pos (lex input-port))]
[(eof) (token-EOF 'eof)]))
(define -parse (cfg-parser
(tokens regexp-tokens)
(start top)
(end EOF)
(src-pos)
(grammar [top [(maybe-anchor regexp)
(cond [$1
`(anchored ,$2 ,(pos->sexp $1-start-pos) ,(pos->sexp $2-end-pos))]
[else
`(unanchored ,$2 ,(pos->sexp $1-start-pos) ,(pos->sexp $2-end-pos))])]]
[maybe-anchor [(ANCHOR) #t]
[() #f]]
[regexp [(regexp STAR) `(star ,$1 ,(pos->sexp $1-start-pos) ,(pos->sexp $2-end-pos))]
[(regexp OR regexp) `(or ,$1 ,$3 ,(pos->sexp $1-start-pos) ,(pos->sexp $3-end-pos))]
[(LPAREN regexp RPAREN) `(group ,$2 ,(pos->sexp $1-start-pos) ,(pos->sexp $3-end-pos))]
[(LIT) `(lit ,$1 ,(pos->sexp $1-start-pos) ,(pos->sexp $1-end-pos))]])))
(define (pos->sexp pos)
(position-offset pos))
(define (parse s)
(define ip (open-input-string s))
(port-count-lines! ip)
(-parse (lambda () (lex ip))))
(check-equal? (parse "abc")
'(unanchored (lit "abc" 1 4) 1 4))
(check-equal? (parse "a | (b*) | c")
'(unanchored (or (or (lit "a" 1 2)
(group (star (lit "b" 6 7) 6 8) 5 9)
1 9)
(lit "c" 12 13)
1 13)
1 13)))
;; Tests used during development
(define-tokens non-terminals (PLUS MINUS STAR BAR COLON EOF))
(define lex
(lexer
["+" (token-PLUS '+)]
["-" (token-MINUS '-)]
["*" (token-STAR '*)]
["|" (token-BAR '||)]
[":" (token-COLON '|:|)]
[whitespace (lex input-port)]
[(eof) (token-EOF 'eof)]))
(define parse
(cfg-parser
(tokens non-terminals)
(start <program>)
(end EOF)
(error (lambda (a b stx)
(error 'parse "failed at ~s" stx)))
(grammar [<program> [(PLUS) "plus"]
[(<minus-program> BAR <minus-program>) (list $1 $2 $3)]
[(<program> COLON) (list $1)]]
[<minus-program> [(MINUS) "minus"]
[(<program> STAR) (cons $1 $2)]]
[<simple> [(<alts> <alts> <alts> MINUS) "yes"]]
[<alts> [(PLUS) 'plus]
[(MINUS) 'minus]]
[<random> [() '0]
[(<random> PLUS) (add1 $1)]
[(<random> PLUS) (add1 $1)]])))
(let ([p (open-input-string #;"+*|-|-*|+**" #;"-|+*|+**"
#;"+*|+**|-" #;"-|-*|-|-*"
#;"-|-*|-|-**|-|-*|-|-**"
"-|-*|-|-**|-|-*|-|-***|-|-*|-|-**|-|-*|-|-****|-|-*|-|-**|-|-*|-|-***
|-|-*|-|-**|-|-*|-|-*****|-|-*|-|-**|-|-*|-|-***|-|-*|-|-**|-|-*|-|-****|
-|-*|-|-**|-|-*|-|-***|-|-*|-|-**|-|-*|-|-*****"
;; This one fails:
#;"+*")])
(check-equal? (parse (lambda () (lex p)))
'((((((((((("minus" || "minus") . *) || (("minus" || "minus") . *)) . *) || (((("minus" || "minus") . *) || (("minus" || "minus") . *)) . *)) . *)
||
(((((("minus" || "minus") . *) || (("minus" || "minus") . *)) . *) || (((("minus" || "minus") . *) || (("minus" || "minus") . *)) . *)) . *))
.
*)
||
(((((((("minus" || "minus") . *) || (("minus" || "minus") . *)) . *) || (((("minus" || "minus") . *) || (("minus" || "minus") . *)) . *)) . *)
||
(((((("minus" || "minus") . *) || (("minus" || "minus") . *)) . *) || (((("minus" || "minus") . *) || (("minus" || "minus") . *)) . *)) . *))
.
*))
.
*)
||
(((((((((("minus" || "minus") . *) || (("minus" || "minus") . *)) . *) || (((("minus" || "minus") . *) || (("minus" || "minus") . *)) . *)) . *)
||
(((((("minus" || "minus") . *) || (("minus" || "minus") . *)) . *) || (((("minus" || "minus") . *) || (("minus" || "minus") . *)) . *)) . *))
.
*)
||
(((((((("minus" || "minus") . *) || (("minus" || "minus") . *)) . *) || (((("minus" || "minus") . *) || (("minus" || "minus") . *)) . *)) . *)
||
(((((("minus" || "minus") . *) || (("minus" || "minus") . *)) . *) || (((("minus" || "minus") . *) || (("minus" || "minus") . *)) . *)) . *))
.
*))
.
*)))))

89
br-parser-tools/br-parser-tools-lib/br-parser-tools/examples/calc.rkt
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#lang scheme
;; An interactive calculator inspired by the calculator example in the bison manual.
;; Import the parser and lexer generators.
(require br-parser-tools/yacc
br-parser-tools/lex
(prefix-in : br-parser-tools/lex-sre))
(define-tokens value-tokens (NUM VAR FNCT))
(define-empty-tokens op-tokens (newline = OP CP + - * / ^ EOF NEG))
;; A hash table to store variable values in for the calculator
(define vars (make-hash))
(define-lex-abbrevs
(lower-letter (:/ "a" "z"))
(upper-letter (:/ #\A #\Z))
;; (:/ 0 9) would not work because the lexer does not understand numbers. (:/ #\0 #\9) is ok too.
(digit (:/ "0" "9")))
(define calcl
(lexer
[(eof) 'EOF]
;; recursively call the lexer on the remaining input after a tab or space. Returning the
;; result of that operation. This effectively skips all whitespace.
[(:or #\tab #\space) (calcl input-port)]
;; (token-newline) returns 'newline
[#\newline (token-newline)]
;; Since (token-=) returns '=, just return the symbol directly
[(:or "=" "+" "-" "*" "/" "^") (string->symbol lexeme)]
["(" 'OP]
[")" 'CP]
["sin" (token-FNCT sin)]
[(:+ (:or lower-letter upper-letter)) (token-VAR (string->symbol lexeme))]
[(:+ digit) (token-NUM (string->number lexeme))]
[(:: (:+ digit) #\. (:* digit)) (token-NUM (string->number lexeme))]))
(define calcp
(parser
(start start)
(end newline EOF)
(tokens value-tokens op-tokens)
(error (lambda (a b c) (void)))
(precs (right =)
(left - +)
(left * /)
(left NEG)
(right ^))
(grammar
(start [() #f]
;; If there is an error, ignore everything before the error
;; and try to start over right after the error
[(error start) $2]
[(exp) $1])
(exp [(NUM) $1]
[(VAR) (hash-ref vars $1 (lambda () 0))]
[(VAR = exp) (begin (hash-set! vars $1 $3)
$3)]
[(FNCT OP exp CP) ($1 $3)]
[(exp + exp) (+ $1 $3)]
[(exp - exp) (- $1 $3)]
[(exp * exp) (* $1 $3)]
[(exp / exp) (/ $1 $3)]
[(- exp) (prec NEG) (- $2)]
[(exp ^ exp) (expt $1 $3)]
[(OP exp CP) $2]))))
;; run the calculator on the given input-port
(define (calc ip)
(port-count-lines! ip)
(letrec ((one-line
(lambda ()
(let ((result (calcp (lambda () (calcl ip)))))
(when result
(printf "~a\n" result)
(one-line))))))
(one-line)))
(calc (open-input-string "x=1\n(x + 2 * 3) - (1+2)*3"))

242
br-parser-tools/br-parser-tools-lib/br-parser-tools/examples/read.rkt
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;; This implements the equivalent of racket's read-syntax for R5RS scheme.
;; It has not been thoroughly tested. Also it will read an entire file into a
;; list of syntax objects, instead of returning one syntax object at a time
(module read mzscheme
(require br-parser-tools/lex
(prefix : br-parser-tools/lex-sre)
br-parser-tools/yacc
syntax/readerr)
(define-tokens data (DATUM))
(define-empty-tokens delim (OP CP HASHOP QUOTE QUASIQUOTE UNQUOTE UNQUOTE-SPLICING DOT EOF))
(define scheme-lexer
(lexer-src-pos
;; Skip comments, without accumulating extra position information
[(:or scheme-whitespace comment) (return-without-pos (scheme-lexer input-port))]
["#t" (token-DATUM #t)]
["#f" (token-DATUM #f)]
[(:: "#\\" any-char) (token-DATUM (caddr (string->list lexeme)))]
["#\\space" (token-DATUM #\space)]
["#\\newline" (token-DATUM #\newline)]
[(:or (:: initial (:* subsequent)) "+" "-" "...") (token-DATUM (string->symbol lexeme))]
[#\" (token-DATUM (list->string (get-string-token input-port)))]
[#\( 'OP]
[#\) 'CP]
[#\[ 'OP]
[#\] 'CP]
["#(" 'HASHOP]
[num2 (token-DATUM (string->number lexeme 2))]
[num8 (token-DATUM (string->number lexeme 8))]
[num10 (token-DATUM (string->number lexeme 10))]
[num16 (token-DATUM (string->number lexeme 16))]
["'" 'QUOTE]
["`" 'QUASIQUOTE]
["," 'UNQUOTE]
[",@" 'UNQUOTE-SPLICING]
["." 'DOT]
[(eof) 'EOF]))
(define get-string-token
(lexer
[(:~ #\" #\\) (cons (car (string->list lexeme))
(get-string-token input-port))]
[(:: #\\ #\\) (cons #\\ (get-string-token input-port))]
[(:: #\\ #\") (cons #\" (get-string-token input-port))]
[#\" null]))
(define-lex-abbrevs
[letter (:or (:/ "a" "z") (:/ #\A #\Z))]
[digit (:/ #\0 #\9)]
[scheme-whitespace (:or #\newline #\return #\tab #\space #\vtab)]
[initial (:or letter (char-set "!$%&*/:<=>?^_~@"))]
[subsequent (:or initial digit (char-set "+-.@"))]
[comment (:: #\; (:* (:~ #\newline)) #\newline)]
;; See ${PLTHOME}/collects/syntax-color/racket-lexer.rkt for an example of
;; using regexp macros to avoid the cut and paste.
; [numR (:: prefixR complexR)]
; [complexR (:or realR
; (:: realR "@" realR)
; (:: realR "+" urealR "i")
; (:: realR "-" urealR "i")
; (:: realR "+i")
; (:: realR "-i")
; (:: "+" urealR "i")
; (:: "-" urealR "i")
; (:: "+i")
; (:: "-i"))]
; [realR (:: sign urealR)]
; [urealR (:or uintegerR (:: uintegerR "/" uintegerR) decimalR)]
; [uintegerR (:: (:+ digitR) (:* #\#))]
; [prefixR (:or (:: radixR exactness)
; (:: exactness radixR))]
[num2 (:: prefix2 complex2)]
[complex2 (:or real2
(:: real2 "@" real2)
(:: real2 "+" ureal2 "i")
(:: real2 "-" ureal2 "i")
(:: real2 "+i")
(:: real2 "-i")
(:: "+" ureal2 "i")
(:: "-" ureal2 "i")
(:: "+i")
(:: "-i"))]
[real2 (:: sign ureal2)]
[ureal2 (:or uinteger2 (:: uinteger2 "/" uinteger2))]
[uinteger2 (:: (:+ digit2) (:* #\#))]
[prefix2 (:or (:: radix2 exactness)
(:: exactness radix2))]
[radix2 "#b"]
[digit2 (:or "0" "1")]
[num8 (:: prefix8 complex8)]
[complex8 (:or real8
(:: real8 "@" real8)
(:: real8 "+" ureal8 "i")
(:: real8 "-" ureal8 "i")
(:: real8 "+i")
(:: real8 "-i")
(:: "+" ureal8 "i")
(:: "-" ureal8 "i")
(:: "+i")
(:: "-i"))]
[real8 (:: sign ureal8)]
[ureal8 (:or uinteger8 (:: uinteger8 "/" uinteger8))]
[uinteger8 (:: (:+ digit8) (:* #\#))]
[prefix8 (:or (:: radix8 exactness)
(:: exactness radix8))]
[radix8 "#o"]
[digit8 (:/ "0" "7")]
[num10 (:: prefix10 complex10)]
[complex10 (:or real10
(:: real10 "@" real10)
(:: real10 "+" ureal10 "i")
(:: real10 "-" ureal10 "i")
(:: real10 "+i")
(:: real10 "-i")
(:: "+" ureal10 "i")
(:: "-" ureal10 "i")
(:: "+i")
(:: "-i"))]
[real10 (:: sign ureal10)]
[ureal10 (:or uinteger10 (:: uinteger10 "/" uinteger10) decimal10)]
[uinteger10 (:: (:+ digit10) (:* #\#))]
[prefix10 (:or (:: radix10 exactness)
(:: exactness radix10))]
[radix10 (:? "#d")]
[digit10 digit]
[decimal10 (:or (:: uinteger10 suffix)
(:: #\. (:+ digit10) (:* #\#) suffix)
(:: (:+ digit10) #\. (:* digit10) (:* #\#) suffix)
(:: (:+ digit10) (:+ #\#) #\. (:* #\#) suffix))]
[num16 (:: prefix16 complex16)]
[complex16 (:or real16
(:: real16 "@" real16)
(:: real16 "+" ureal16 "i")
(:: real16 "-" ureal16 "i")
(:: real16 "+i")
(:: real16 "-i")
(:: "+" ureal16 "i")
(:: "-" ureal16 "i")
"+i"
"-i")]
[real16 (:: sign ureal16)]
[ureal16 (:or uinteger16 (:: uinteger16 "/" uinteger16))]
[uinteger16 (:: (:+ digit16) (:* #\#))]
[prefix16 (:or (:: radix16 exactness)
(:: exactness radix16))]
[radix16 "#x"]
[digit16 (:or digit (:/ #\a #\f) (:/ #\A #\F))]
[suffix (:or "" (:: exponent-marker sign (:+ digit10)))]
[exponent-marker (:or "e" "s" "f" "d" "l")]
[sign (:or "" "+" "-")]
[exactness (:or "" "#i" "#e")])
(define stx-for-original-property (read-syntax #f (open-input-string "original")))
;; A macro to build the syntax object
(define-syntax (build-so stx)
(syntax-case stx ()
((_ value start end)
(with-syntax ((start-pos (datum->syntax-object
(syntax end)
(string->symbol
(format "$~a-start-pos"
(syntax-object->datum (syntax start))))))
(end-pos (datum->syntax-object
(syntax end)
(string->symbol
(format "$~a-end-pos"
(syntax-object->datum (syntax end))))))
(source (datum->syntax-object
(syntax end)
'source-name)))
(syntax
(datum->syntax-object
#f
value
(list source
(position-line start-pos)
(position-col start-pos)
(position-offset start-pos)
(- (position-offset end-pos)
(position-offset start-pos)))
stx-for-original-property))))))
(define (scheme-parser source-name)
(parser
(src-pos)
(start s)
(end EOF)
(error (lambda (a name val start end)
(raise-read-error
"read-error"
source-name
(position-line start)
(position-col start)
(position-offset start)
(- (position-offset end)
(position-offset start)))))
(tokens data delim)
(grammar
(s [(sexp-list) (reverse $1)])
(sexp [(DATUM) (build-so $1 1 1)]
[(OP sexp-list CP) (build-so (reverse $2) 1 3)]
[(HASHOP sexp-list CP) (build-so (list->vector (reverse $2)) 1 3)]
[(QUOTE sexp) (build-so (list 'quote $2) 1 2)]
[(QUASIQUOTE sexp) (build-so (list 'quasiquote $2) 1 2)]
[(UNQUOTE sexp) (build-so (list 'unquote $2) 1 2)]
[(UNQUOTE-SPLICING sexp) (build-so (list 'unquote-splicing $2) 1 2)]
[(OP sexp-list DOT sexp CP) (build-so (append (reverse $2) $4) 1 5)])
(sexp-list [() null]
[(sexp-list sexp) (cons $2 $1)]))))
(define (rs sn ip)
(port-count-lines! ip)
((scheme-parser sn) (lambda () (scheme-lexer ip))))
(define readsyntax
(case-lambda ((sn) (rs sn (current-input-port)))
((sn ip) (rs sn ip))))
(provide (rename readsyntax read-syntax))
)

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br-parser-tools/br-parser-tools-lib/br-parser-tools/info.rkt
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#lang info
(define compile-omit-paths '("private-lex/error-tests.rkt"))

24
br-parser-tools/br-parser-tools-lib/br-parser-tools/lex-plt-v200.rkt
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(module lex-plt-v200 mzscheme
(require br-parser-tools/lex
(prefix : br-parser-tools/lex-sre))
(provide epsilon
~
(rename :* *)
(rename :+ +)
(rename :? ?)
(rename :or :)
(rename :& &)
(rename :: @)
(rename :~ ^)
(rename :/ -))
(define-lex-trans epsilon
(syntax-rules ()
((_) "")))
(define-lex-trans ~
(syntax-rules ()
((_ re) (complement re)))))

119
br-parser-tools/br-parser-tools-lib/br-parser-tools/lex-sre.rkt
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(module lex-sre mzscheme
(require br-parser-tools/lex)
(provide (rename sre-* *)
(rename sre-+ +)
?
(rename sre-= =)
(rename sre->= >=)
**
(rename sre-or or)
:
seq
&
~
(rename sre-- -)
(rename sre-/ /)
/-only-chars)
(define-lex-trans sre-*
(syntax-rules ()
((_ re ...)
(repetition 0 +inf.0 (union re ...)))))
(define-lex-trans sre-+
(syntax-rules ()
((_ re ...)
(repetition 1 +inf.0 (union re ...)))))
(define-lex-trans ?
(syntax-rules ()
((_ re ...)
(repetition 0 1 (union re ...)))))
(define-lex-trans sre-=
(syntax-rules ()
((_ n re ...)
(repetition n n (union re ...)))))
(define-lex-trans sre->=
(syntax-rules ()
((_ n re ...)
(repetition n +inf.0 (union re ...)))))
(define-lex-trans **
(syntax-rules ()
((_ low #f re ...)
(** low +inf.0 re ...))
((_ low high re ...)
(repetition low high (union re ...)))))
(define-lex-trans sre-or
(syntax-rules ()
((_ re ...)
(union re ...))))
(define-lex-trans :
(syntax-rules ()
((_ re ...)
(concatenation re ...))))
(define-lex-trans seq
(syntax-rules ()
((_ re ...)
(concatenation re ...))))
(define-lex-trans &
(syntax-rules ()
((_ re ...)
(intersection re ...))))
(define-lex-trans ~
(syntax-rules ()
((_ re ...)
(char-complement (union re ...)))))
;; set difference
(define-lex-trans (sre-- stx)
(syntax-case stx ()
((_)
(raise-syntax-error #f
"must have at least one argument"
stx))
((_ big-re re ...)
(syntax (& big-re (complement (union re ...)))))))
(define-lex-trans (sre-/ stx)
(syntax-case stx ()
((_ range ...)
(let ((chars
(apply append (map (lambda (r)
(let ((x (syntax-e r)))
(cond
((char? x) (list x))
((string? x) (string->list x))
(else
(raise-syntax-error
#f
"not a char or string"
stx
r)))))
(syntax->list (syntax (range ...)))))))
(unless (even? (length chars))
(raise-syntax-error
#f
"not given an even number of characters"
stx))
#`(/-only-chars #,@chars)))))
(define-lex-trans /-only-chars
(syntax-rules ()
((_ c1 c2)
(char-range c1 c2))
((_ c1 c2 c ...)
(union (char-range c1 c2)
(/-only-chars c ...)))))
)

369
br-parser-tools/br-parser-tools-lib/br-parser-tools/lex.rkt
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#lang racket/base
;; Provides the syntax used to create lexers and the functions needed to
;; create and use the buffer that the lexer reads from. See docs.
(require (for-syntax mzlib/list
syntax/stx
syntax/define
syntax/boundmap
"private-lex/util.rkt"
"private-lex/actions.rkt"
"private-lex/front.rkt"
"private-lex/unicode-chars.rkt"
racket/base
racket/promise))
(require mzlib/stxparam
syntax/readerr
"private-lex/token.rkt")
(provide lexer lexer-src-pos lexer-srcloc define-lex-abbrev define-lex-abbrevs define-lex-trans
;; Dealing with tokens and related structures
define-tokens define-empty-tokens token-name token-value token?
(struct-out position)
(struct-out position-token)
(struct-out srcloc-token)
;; File path for highlighting errors while lexing
file-path
lexer-file-path ;; alternate name
;; Lex abbrevs for unicode char sets. See mzscheme manual section 3.4.
any-char any-string nothing alphabetic lower-case upper-case title-case
numeric symbolic punctuation graphic whitespace blank iso-control
;; A regular expression operator
char-set)
;; wrap-action: syntax-object src-pos? -> syntax-object
(define-for-syntax (wrap-action action src-loc-style)
(with-syntax ([action-stx
(cond
[(eq? src-loc-style 'lexer-src-pos)
#`(let/ec ret
(syntax-parameterize
([return-without-pos (make-rename-transformer #'ret)])
(make-position-token #,action start-pos end-pos)))]
[(eq? src-loc-style 'lexer-srcloc)
#`(let/ec ret
(syntax-parameterize
([return-without-srcloc (make-rename-transformer #'ret)])
(make-srcloc-token #,action lexeme-srcloc)))]
[else action])])
(syntax/loc action
(λ (start-pos-p end-pos-p lexeme-p input-port-p)
(define lexeme-srcloc-p (make-srcloc (object-name input-port-p)
(position-line start-pos-p)
(position-col start-pos-p)
(position-offset start-pos-p)
(and (number? (position-offset end-pos-p))
(number? (position-offset start-pos-p))
(- (position-offset end-pos-p)
(position-offset start-pos-p)))))
(syntax-parameterize
([start-pos (make-rename-transformer #'start-pos-p)]
[end-pos (make-rename-transformer #'end-pos-p)]
[lexeme (make-rename-transformer #'lexeme-p)]
[input-port (make-rename-transformer #'input-port-p)]
[lexeme-srcloc (make-rename-transformer #'lexeme-srcloc-p)])
action-stx)))))
(define-for-syntax (make-lexer-macro caller src-loc-style)
(λ (stx)
(syntax-case stx ()
[(_ . RE+ACTS)
(let ()
(define spec/re-acts (syntax->list #'RE+ACTS))
(for/and ([x (in-list spec/re-acts)])
(syntax-case x ()
[(RE ACT) #t]
[else (raise-syntax-error caller "not a regular expression / action pair" stx x)]))
(define eof-act (get-special-action spec/re-acts #'eof #'eof))
(define spec-act (get-special-action spec/re-acts #'special #'(void)))
(define spec-comment-act (get-special-action spec/re-acts #'special-comment #'#f))
(define ids (list #'special #'special-comment #'eof))
(define re-acts (filter (λ (spec/re-act)
(syntax-case spec/re-act ()
[((special) act)
(not (ormap
(λ (x)
(and (identifier? #'special)
(module-or-top-identifier=? #'special x)))
ids))]
[_ #t])) spec/re-acts))
(define names (map (λ (x) (datum->syntax #f (gensym))) re-acts))
(define acts (map (λ (x) (stx-car (stx-cdr x))) re-acts))
(define re-actnames (map (λ (re-act name) (list (stx-car re-act) name)) re-acts names))
(when (null? spec/re-acts)
(raise-syntax-error caller "expected at least one action" stx))
(define-values (trans start action-names no-look disappeared-uses) (build-lexer re-actnames))
(when (vector-ref action-names start) ;; Start state is final
(unless (and
;; All the successor states are final
(vector? (vector-ref trans start))
(andmap (λ (x) (vector-ref action-names (vector-ref x 2)))
(vector->list (vector-ref trans start)))
;; Each character has a successor state
(let loop ([check 0]
[nexts (vector->list (vector-ref trans start))])
(cond
[(null? nexts) #f]
[else
(let ([next (car nexts)])
(and (= (vector-ref next 0) check)
(let ([next-check (vector-ref next 1)])
(or (>= next-check max-char-num)
(loop (add1 next-check) (cdr nexts))))))])))
(eprintf "warning: lexer at ~a can accept the empty string\n" stx)))
(with-syntax ([START-STATE-STX start]
[TRANS-TABLE-STX trans]
[NO-LOOKAHEAD-STX no-look]
[(NAME ...) names]
[(ACT ...) (map (λ (a) (wrap-action a src-loc-style)) acts)]
[(ACT-NAME ...) (vector->list action-names)]
[SPEC-ACT-STX (wrap-action spec-act src-loc-style)]
[HAS-COMMENT-ACT?-STX (if (syntax-e spec-comment-act) #t #f)]
[SPEC-COMMENT-ACT-STX (wrap-action spec-comment-act src-loc-style)]
[EOF-ACT-STX (wrap-action eof-act src-loc-style)])
(syntax-property
(syntax/loc stx (let ([NAME ACT] ...)
(let ([proc (lexer-body START-STATE-STX
TRANS-TABLE-STX
(vector ACT-NAME ...)
NO-LOOKAHEAD-STX
SPEC-ACT-STX
HAS-COMMENT-ACT?-STX
SPEC-COMMENT-ACT-STX
EOF-ACT-STX)])
;; reverse eta to get named procedures:
(λ (port) (proc port)))))
'disappeared-use disappeared-uses)))])))
(define-syntax lexer (make-lexer-macro 'lexer #f))
(define-syntax lexer-src-pos (make-lexer-macro 'lexer-src-pos 'lexer-src-pos))
(define-syntax lexer-srcloc (make-lexer-macro 'lexer-srcloc 'lexer-srcloc))
(define-syntax (define-lex-abbrev stx)
(syntax-case stx ()
[(_ NAME RE) (identifier? #'NAME)
(syntax/loc stx
(define-syntax NAME
(make-lex-abbrev (λ () (quote-syntax RE)))))]
[_ (raise-syntax-error 'define-lex-abbrev "form should be (define-lex-abbrev name re)" stx)]))
(define-syntax (define-lex-abbrevs stx)
(syntax-case stx ()
[(_ . XS)
(with-syntax ([(ABBREV ...) (map
(λ (a)
(syntax-case a ()
[(NAME RE) (identifier? #'NAME)
(syntax/loc a (define-lex-abbrev NAME RE))]
[_ (raise-syntax-error
#f
"form should be (define-lex-abbrevs (name re) ...)"
stx
a)]))
(syntax->list #'XS))])
(syntax/loc stx (begin ABBREV ...)))]
[_ (raise-syntax-error #f "form should be (define-lex-abbrevs (name re) ...)" stx)]))
(define-syntax (define-lex-trans stx)
(syntax-case stx ()
[(_ name-form body-form)
(let-values (((name body)
(normalize-definition #'(define-syntax name-form body-form) #'λ)))
#`(define-syntax #,name
(let ((func #,body))
(unless (procedure? func)
(raise-syntax-error 'define-lex-trans "expected a procedure as the transformer, got ~e" func))
(unless (procedure-arity-includes? func 1)
(raise-syntax-error 'define-lex-trans "expected a procedure that accepts 1 argument as the transformer, got ~e" func))
(make-lex-trans func))))]
[_
(raise-syntax-error
#f
"form should be (define-lex-trans name transformer)"
stx)]))
(define (get-next-state-helper char min max table)
(cond
[(>= min max) #f]
[else
(define try (quotient (+ min max) 2))
(define el (vector-ref table try))
(define r1 (vector-ref el 0))
(define r2 (vector-ref el 1))
(cond
[(and (>= char r1) (<= char r2)) (vector-ref el 2)]
[(< char r1) (get-next-state-helper char min try table)]
[else (get-next-state-helper char (add1 try) max table)])]))
(define (get-next-state char table)
(and table (get-next-state-helper char 0 (vector-length table) table)))
(define (lexer-body start-state trans-table actions no-lookahead special-action
has-special-comment-action? special-comment-action eof-action)
(letrec ([lexer
(λ (ip)
(let ((first-pos (get-position ip))
(first-char (peek-char-or-special ip 0)))
;(printf "(peek-char-or-special port 0) = ~e\n" first-char)
(cond
[(eof-object? first-char)
(do-match ip first-pos eof-action (read-char-or-special ip))]
[(special-comment? first-char)
(read-char-or-special ip)
(cond
(has-special-comment-action?
(do-match ip first-pos special-comment-action #f))
(else (lexer ip)))]
[(not (char? first-char))
(do-match ip first-pos special-action (read-char-or-special ip))]
[else
(let lexer-loop (
;; current-state
(state start-state)
;; the character to transition on
(char first-char)
;; action for the longest match seen thus far
;; including a match at the current state
(longest-match-action
(vector-ref actions start-state))
;; how many bytes precede char
(length-bytes 0)
;; how many characters have been read
;; including the one just read
(length-chars 1)
;; how many characters are in the longest match
(longest-match-length 0))
(let ([next-state
(cond
[(not (char? char)) #f]
[else (get-next-state (char->integer char)
(vector-ref trans-table state))])])
(cond
[(not next-state)
(check-match ip first-pos longest-match-length
length-chars longest-match-action)]
[(vector-ref no-lookahead next-state)
(let ((act (vector-ref actions next-state)))
(check-match ip
first-pos
(if act length-chars longest-match-length)
length-chars
(if act act longest-match-action)))]
[else
(let* ([act (vector-ref actions next-state)]
[next-length-bytes (+ (char-utf-8-length char) length-bytes)]
[next-char (peek-char-or-special ip next-length-bytes)])
#;(printf "(peek-char-or-special port ~e) = ~e\n"
next-length-bytes next-char)
(lexer-loop next-state
next-char
(if act
act
longest-match-action)
next-length-bytes
(add1 length-chars)
(if act
length-chars
longest-match-length)))])))])))])
(λ (ip)
(unless (input-port? ip)
(raise-argument-error 'lexer "input-port?" 0 ip))
(lexer ip))))
(define (check-match lb first-pos longest-match-length length longest-match-action)
(unless longest-match-action
(let* ([match (read-string length lb)]
[end-pos (get-position lb)])
(raise-read-error
(format "lexer: No match found in input starting with: ~a" match)
(file-path)
(position-line first-pos)
(position-col first-pos)
(position-offset first-pos)
(- (position-offset end-pos) (position-offset first-pos)))))
(let ([match (read-string longest-match-length lb)])
;(printf "(read-string ~e port) = ~e\n" longest-match-length match)
(do-match lb first-pos longest-match-action match)))
(define file-path (make-parameter #f))
(define lexer-file-path file-path)
(define (do-match ip first-pos action value)
#;(printf "(action ~a ~a ~a ~a)\n"
(position-offset first-pos) (position-offset (get-position ip)) value ip)
(action first-pos (get-position ip) value ip))
(define (get-position ip)
(define-values (line col off) (port-next-location ip))
(make-position off line col))
(define-syntax (create-unicode-abbrevs stx)
(syntax-case stx ()
[(_ CTXT)
(with-syntax ([(RANGES ...) (for/list ([range (in-list (list (force alphabetic-ranges)
(force lower-case-ranges)
(force upper-case-ranges)
(force title-case-ranges)
(force numeric-ranges)
(force symbolic-ranges)
(force punctuation-ranges)
(force graphic-ranges)
(force whitespace-ranges)
(force blank-ranges)
(force iso-control-ranges)))])
`(union ,@(map (λ (x)
`(char-range ,(integer->char (car x))
,(integer->char (cdr x))))
range)))]
[(NAMES ...) (for/list ([sym (in-list '(alphabetic
lower-case
upper-case
title-case
numeric
symbolic
punctuation
graphic
whitespace
blank
iso-control))])
(datum->syntax #'CTXT sym #f))])
#'(define-lex-abbrevs (NAMES RANGES) ...))]))
(define-lex-abbrev any-char (char-complement (union)))
(define-lex-abbrev any-string (intersection))
(define-lex-abbrev nothing (union))
(create-unicode-abbrevs #'here)
(define-lex-trans (char-set stx)
(syntax-case stx ()
[(_ STR)
(string? (syntax-e #'STR))
(with-syntax ([(CHAR ...) (string->list (syntax-e #'STR))])
#'(union CHAR ...))]))
(define-syntax provide-lex-keyword
(syntax-rules ()
[(_ ID ...)
(begin
(define-syntax-parameter ID
(make-set!-transformer
(λ (stx)
(raise-syntax-error
'provide-lex-keyword
(format "use of a lexer keyword (~a) is not in an appropriate lexer action" 'ID)
stx))))
...
(provide ID ...))]))
(provide-lex-keyword start-pos end-pos lexeme lexeme-srcloc input-port return-without-pos return-without-srcloc)

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br-parser-tools/br-parser-tools-lib/br-parser-tools/private-lex/actions.rkt
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#lang racket/base
(provide (all-defined-out))
(require syntax/stx)
;; get-special-action: (syntax-object list) syntax-object syntax-object -> syntax-object
;; Returns the first action from a rule of the form ((which-special) action)
(define (get-special-action rules which-special none)
(cond
((null? rules) none)
(else
(syntax-case (car rules) ()
[((special) ACT)
(and (identifier? #'special) (module-or-top-identifier=? (syntax special) which-special))
#'ACT]
[_ (get-special-action (cdr rules) which-special none)]))))

339
br-parser-tools/br-parser-tools-lib/br-parser-tools/private-lex/deriv.rkt
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(module deriv mzscheme
(require mzlib/list
(prefix is: mzlib/integer-set)
"re.rkt"
"util.rkt")
(provide build-dfa print-dfa (struct dfa (num-states start-state final-states/actions transitions)))
(define e (build-epsilon))
(define z (build-zero))
;; Don't do anything with this one but extract the chars
(define all-chars (->re `(char-complement (union)) (make-cache)))
;; get-char-groups : re bool -> (list-of char-setR?)
;; Collects the char-setRs in r that could be used in
;; taking the derivative of r.
(define (get-char-groups r found-negation)
(cond
((or (eq? r e) (eq? r z)) null)
((char-setR? r) (list r))
((concatR? r)
(if (re-nullable? (concatR-re1 r))
(append (get-char-groups (concatR-re1 r) found-negation)
(get-char-groups (concatR-re2 r) found-negation))
(get-char-groups (concatR-re1 r) found-negation)))
((repeatR? r)
(get-char-groups (repeatR-re r) found-negation))
((orR? r)
(apply append (map (lambda (x) (get-char-groups x found-negation)) (orR-res r))))
((andR? r)
(apply append (map (lambda (x) (get-char-groups x found-negation)) (andR-res r))))
((negR? r)
(if found-negation
(get-char-groups (negR-re r) #t)
(cons all-chars (get-char-groups (negR-re r) #t))))))
(test-block ((c (make-cache))
(r1 (->re #\1 c))
(r2 (->re #\2 c)))
((get-char-groups e #f) null)
((get-char-groups z #f) null)
((get-char-groups r1 #f) (list r1))
((get-char-groups (->re `(concatenation ,r1 ,r2) c) #f)
(list r1))
((get-char-groups (->re `(concatenation ,e ,r2) c) #f)
(list r2))
((get-char-groups (->re `(concatenation (repetition 0 +inf.0 ,r1) ,r2) c) #f)
(list r1 r2))
((get-char-groups (->re `(repetition 0 +inf.0 ,r1) c) #f)
(list r1))
((get-char-groups
(->re `(union (repetition 0 +inf.0 ,r1)
(concatenation (repetition 0 +inf.0 ,r2) "3") "4") c) #f)
(list r1 r2 (->re "3" c) (->re "4" c)))
((get-char-groups (->re `(complement ,r1) c) #f)
(list all-chars r1))
((get-char-groups
(->re `(intersection (repetition 0 +inf.0 ,r1)
(concatenation (repetition 0 +inf.0 ,r2) "3") "4") c) #f)
(list r1 r2 (->re "3" c) (->re "4" c)))
)
(define loc:member? is:member?)
;; deriveR : re char cache -> re
(define (deriveR r c cache)
(cond
((or (eq? r e) (eq? r z)) z)
((char-setR? r)
(if (loc:member? c (char-setR-chars r)) e z))
((concatR? r)
(let* ((r1 (concatR-re1 r))
(r2 (concatR-re2 r))
(d (build-concat (deriveR r1 c cache) r2 cache)))
(if (re-nullable? r1)
(build-or (list d (deriveR r2 c cache)) cache)
d)))
((repeatR? r)
(build-concat (deriveR (repeatR-re r) c cache)
(build-repeat (sub1 (repeatR-low r))
(sub1 (repeatR-high r))
(repeatR-re r) cache)
cache))
((orR? r)
(build-or (map (lambda (x) (deriveR x c cache))
(orR-res r))
cache))
((andR? r)
(build-and (map (lambda (x) (deriveR x c cache))
(andR-res r))
cache))
((negR? r)
(build-neg (deriveR (negR-re r) c cache) cache))))
(test-block ((c (make-cache))
(a (char->integer #\a))
(b (char->integer #\b))
(r1 (->re #\a c))
(r2 (->re `(repetition 0 +inf.0 #\a) c))
(r3 (->re `(repetition 0 +inf.0 ,r2) c))
(r4 (->re `(concatenation #\a ,r2) c))
(r5 (->re `(repetition 0 +inf.0 ,r4) c))
(r6 (->re `(union ,r5 #\a) c))
(r7 (->re `(concatenation ,r2 ,r2) c))
(r8 (->re `(complement ,r4) c))
(r9 (->re `(intersection ,r2 ,r4) c)))
((deriveR e a c) z)
((deriveR z a c) z)
((deriveR r1 b c) z)
((deriveR r1 a c) e)
((deriveR r2 a c) r2)
((deriveR r2 b c) z)
((deriveR r3 a c) r2)
((deriveR r3 b c) z)
((deriveR r4 a c) r2)
((deriveR r4 b c) z)
((deriveR r5 a c) (->re `(concatenation ,r2 ,r5) c))
((deriveR r5 b c) z)
((deriveR r6 a c) (->re `(union (concatenation ,r2 ,r5) "") c))
((deriveR r6 b c) z)
((deriveR r7 a c) (->re `(union (concatenation ,r2 ,r2) ,r2) c))
((deriveR r7 b c) z)
((deriveR r8 a c) (->re `(complement, r2) c))
((deriveR r8 b c) (->re `(complement ,z) c))
((deriveR r9 a c) r2)
((deriveR r9 b c) z)
((deriveR (->re `(repetition 1 2 "ab") c) a c)
(->re `(concatenation "b" (repetition 0 1 "ab")) c)))
;; An re-action is (cons re action)
;; derive : (list-of re-action) char cache -> (union (list-of re-action) #f)
;; applies deriveR to all the re-actions's re parts.
;; Returns #f if the derived state is equivalent to z.
(define (derive r c cache)
(let ((new-r (map (lambda (ra)
(cons (deriveR (car ra) c cache) (cdr ra)))
r)))
(if (andmap (lambda (x) (eq? z (car x)))
new-r)
#f
new-r)))
(test-block ((c (make-cache))
(r1 (->re #\1 c))
(r2 (->re #\2 c)))
((derive null (char->integer #\1) c) #f)
((derive (list (cons r1 1) (cons r2 2)) (char->integer #\1) c)
(list (cons e 1) (cons z 2)))
((derive (list (cons r1 1) (cons r2 2)) (char->integer #\3) c) #f))
;; get-final : (list-of re-action) -> (union #f syntax-object)
;; An re that accepts e represents a final state. Return the
;; action from the first final state or #f if there is none.
(define (get-final res)
(cond
((null? res) #f)
((re-nullable? (caar res)) (cdar res))
(else (get-final (cdr res)))))
(test-block ((c->i char->integer)
(c (make-cache))
(r1 (->re #\a c))
(r2 (->re #\b c))
(b (list (cons z 1) (cons z 2) (cons z 3) (cons e 4) (cons z 5)))
(a (list (cons r1 1) (cons r2 2))))
((derive null (c->i #\a) c) #f)
((derive a (c->i #\a) c) (list (cons e 1) (cons z 2)))
((derive a (c->i #\b) c) (list (cons z 1) (cons e 2)))
((derive a (c->i #\c) c) #f)
((derive (list (cons (->re `(union " " "\n" ",") c) 1)
(cons (->re `(concatenation (repetition 0 1 "-")
(repetition 1 +inf.0 (char-range "0" "9"))) c) 2)
(cons (->re `(concatenation "-" (repetition 1 +inf.0 "-")) c) 3)
(cons (->re "[" c) 4)
(cons (->re "]" c) 5)) (c->i #\[) c)
b)
((get-final a) #f)
((get-final (list (cons e 1) (cons e 2))) 1)
((get-final b) 4))
;; A state is (make-state (list-of re-action) nat)
(define-struct state (spec index))
;; get->key : re-action -> (list-of nat)
;; states are indexed by the list of indexes of their res
(define (get-key s)
(map (lambda (x) (re-index (car x))) s))
(define loc:partition is:partition)
;; compute-chars : (list-of state) -> (list-of char-set)
;; Computed the sets of equivalent characters for taking the
;; derivative of the car of st. Only one derivative per set need to be taken.
(define (compute-chars st)
(cond
((null? st) null)
(else
(loc:partition (map char-setR-chars
(apply append (map (lambda (x) (get-char-groups (car x) #f))
(state-spec (car st)))))))))
(test-block ((c (make-cache))
(c->i char->integer)
(r1 (->re `(char-range #\1 #\4) c))
(r2 (->re `(char-range #\2 #\3) c)))
((compute-chars null) null)
((compute-chars (list (make-state null 1))) null)
((map is:integer-set-contents
(compute-chars (list (make-state (list (cons r1 1) (cons r2 2)) 2))))
(list (is:integer-set-contents (is:make-range (c->i #\2) (c->i #\3)))
(is:integer-set-contents (is:union (is:make-range (c->i #\1))
(is:make-range (c->i #\4)))))))
;; A dfa is (make-dfa int int
;; (list-of (cons int syntax-object))
;; (list-of (cons int (list-of (cons char-set int)))))
;; Each transitions is a state and a list of chars with the state to transition to.
;; The finals and transitions are sorted by state number, and duplicate free.
(define-struct dfa (num-states start-state final-states/actions transitions) (make-inspector))
(define loc:get-integer is:get-integer)
;; build-dfa : (list-of re-action) cache -> dfa
(define (build-dfa rs cache)
(let* ((transitions (make-hash-table))
(get-state-number (make-counter))
(start (make-state rs (get-state-number))))
(cache (cons 'state (get-key rs)) (lambda () start))
(let loop ((old-states (list start))
(new-states null)
(all-states (list start))
(cs (compute-chars (list start))))
(cond
((and (null? old-states) (null? new-states))
(make-dfa (get-state-number) (state-index start)
(sort (filter (lambda (x) (cdr x))
(map (lambda (state)
(cons (state-index state) (get-final (state-spec state))))
all-states))
(lambda (a b) (< (car a) (car b))))
(sort (hash-table-map transitions
(lambda (state trans)
(cons (state-index state)
(map (lambda (t)
(cons (car t)
(state-index (cdr t))))
trans))))
(lambda (a b) (< (car a) (car b))))))
((null? old-states)
(loop new-states null all-states (compute-chars new-states)))
((null? cs)
(loop (cdr old-states) new-states all-states (compute-chars (cdr old-states))))
(else
(let* ((state (car old-states))
(c (car cs))
(new-re (derive (state-spec state) (loc:get-integer c) cache)))
(cond
(new-re
(let* ((new-state? #f)
(new-state (cache (cons 'state (get-key new-re))
(lambda ()
(set! new-state? #t)
(make-state new-re (get-state-number)))))
(new-all-states (if new-state? (cons new-state all-states) all-states)))
(hash-table-put! transitions
state
(cons (cons c new-state)
(hash-table-get transitions state
(lambda () null))))
(cond
(new-state?
(loop old-states (cons new-state new-states) new-all-states (cdr cs)))
(else
(loop old-states new-states new-all-states (cdr cs))))))
(else (loop old-states new-states all-states (cdr cs))))))))))
(define (print-dfa x)
(printf "number of states: ~a\n" (dfa-num-states x))
(printf "start state: ~a\n" (dfa-start-state x))
(printf "final states: ~a\n" (map car (dfa-final-states/actions x)))
(for-each (lambda (trans)
(printf "state: ~a\n" (car trans))
(for-each (lambda (rule)
(printf " -~a-> ~a\n"
(is:integer-set-contents (car rule))
(cdr rule)))
(cdr trans)))
(dfa-transitions x)))
(define (build-test-dfa rs)
(let ((c (make-cache)))
(build-dfa (map (lambda (x) (cons (->re x c) 'action))
rs)
c)))
#|
(define t1 (build-test-dfa null))
(define t2 (build-test-dfa `(#\a)))
(define t3 (build-test-dfa `(#\a #\b)))
(define t4 (build-test-dfa `((repetition 0 +inf.0 #\a)
(repetition 0 +inf.0 (concatenation #\a #\b)))))
(define t5 (build-test-dfa `((concatenation (repetition 0 +inf.0 (union #\0 #\1)) #\1))))
(define t6 (build-test-dfa `((repetition 0 +inf.0 (repetition 0 +inf.0 #\a))
(repetition 0 +inf.0 (concatenation #\b (repetition 1 +inf.0 #\b))))))
(define t7 (build-test-dfa `((concatenation (repetition 0 +inf.0 #\a) (repetition 0 +inf.0 #\b)
(repetition 0 +inf.0 #\c) (repetition 0 +inf.0 #\d)
(repetition 0 +inf.0 #\e)))))
(define t8
(build-test-dfa `((concatenation (repetition 0 +inf.0 (union #\a #\b)) #\a (union #\a #\b)
(union #\a #\b) (union #\a #\b) (union #\a #\b)))))
(define t9 (build-test-dfa `((concatenation "/*"
(complement (concatenation (intersection) "*/" (intersection)))
"*/"))))
(define t11 (build-test-dfa `((complement "1"))))
(define t12 (build-test-dfa `((concatenation (intersection (concatenation (repetition 0 +inf.0 "a") "b")
(concatenation "a" (repetition 0 +inf.0 "b")))
"ab"))))
(define x (build-test-dfa `((union " " "\n" ",")
(concatenation (repetition 0 1 "-") (repetition 1 +inf.0 (char-range "0" "9")))
(concatenation "-" (repetition 1 +inf.0 "-"))
"["
"]")))
(define y (build-test-dfa
`((repetition 1 +inf.0
(union (concatenation "|" (repetition 0 +inf.0 (char-complement "|")) "|")
(concatenation "|" (repetition 0 +inf.0 (char-complement "|"))))))))
(define t13 (build-test-dfa `((intersection (concatenation (intersection) "111" (intersection))
(complement (union (concatenation (intersection) "01")
(repetition 1 +inf.0 "1")))))))
(define t14 (build-test-dfa `((complement "1"))))
|#
)

81
br-parser-tools/br-parser-tools-lib/br-parser-tools/private-lex/error-tests.rkt
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#lang scheme/base
(require (for-syntax scheme/base)
"../lex.rkt"
rackunit)
(define-syntax (catch-syn-error stx)
(syntax-case stx ()
[(_ arg)
(datum->syntax
#'here
(with-handlers ((exn:fail:syntax? exn-message))
(syntax-local-expand-expression #'arg)
"not-an-error"))]))
(check-regexp-match #rx"lex-abbrev" (catch-syn-error (define-lex-abbrev)))
(check-regexp-match #rx"lex-abbrev" (catch-syn-error (define-lex-abbrev a)))
(check-regexp-match #rx"lex-abbrev" (catch-syn-error (define-lex-abbrev (a b) v)))
(check-regexp-match #rx"lex-abbrev" (catch-syn-error (define-lex-abbrev 1 1)))
(check-regexp-match #rx"lex-abbrevs" (catch-syn-error (define-lex-abbrevs ())))
(check-regexp-match #rx"lex-trans" (catch-syn-error (define-lex-trans)))
(check-regexp-match #rx"lexer" (catch-syn-error (lexer)))
(check-regexp-match #rx"lexer" (catch-syn-error (lexer ("a" "b" "c"))))
(check-regexp-match #rx"lexer" (catch-syn-error (lexer ())))
(check-regexp-match #rx"lexer" (catch-syn-error (lexer (""))))
(check-regexp-match #rx"regular-expression" (catch-syn-error (lexer (a 1))))
(check-regexp-match #rx"regular-expression" (catch-syn-error (lexer ((a) 1))))
(check-regexp-match #rx"regular-expression" (catch-syn-error (let ((a 1)) (lexer ((a) 1)))))
(check-regexp-match #rx"regular-expression"
(catch-syn-error (let-syntax ((a 1))
(lexer ((a) 1)))))
(check-regexp-match #rx"define-lex-trans"
(catch-syn-error
(let ()
(define-lex-trans a 1)
(let ()
(lexer ((a) 1))))))
;; Detecting mutual recursion cycle:
(check-regexp-match #rx"regular-expression"
(catch-syn-error
(let ()
(define-lex-abbrev a b)
(define-lex-abbrev b a)
(let ()
(lexer (a 1))))))
(check-regexp-match #rx"regular-expression"
(catch-syn-error
(let ()
(define-lex-abbrev a (repetition 0 1 b))
(define-lex-abbrev b (repetition 0 1 a))
(let ()
(lexer (a 1))))))
;; Detecting cycle within same abbreviation:
(check-regexp-match #rx"regular-expression"
(catch-syn-error
(let ()
(define-lex-abbrev balanced
(union (concatenation "(" balanced ")" balanced)
any-char))
(lexer
[balanced (string-append lexeme (balanced input-port))]
[(eof) ""]))))
(check-regexp-match #rx"regular-expression" (catch-syn-error (lexer (1 1))))
(check-regexp-match #rx"repetition" (catch-syn-error (lexer ((repetition) 1))))
(check-regexp-match #rx"repetition" (catch-syn-error (lexer ((repetition #\1 #\1 "3") 1))))
(check-regexp-match #rx"repetition" (catch-syn-error (lexer ((repetition 1 #\1 "3") 1))))
(check-regexp-match #rx"repetition" (catch-syn-error (lexer ((repetition 1 0 "3") 1))))
(check-regexp-match #rx"complement" (catch-syn-error (lexer ((complement) 1))))
(check-regexp-match #rx"char-range" (catch-syn-error (lexer ((char-range) 1))))
(check-regexp-match #rx"char-range" (catch-syn-error (lexer ((char-range #\9 #\0) 1))))
(check-regexp-match #rx"char-complement" (catch-syn-error (lexer ((char-complement) 1))))
(check-regexp-match #rx"char-complement" (catch-syn-error (lexer ((char-complement (concatenation "1" "2")) 1))))

179
br-parser-tools/br-parser-tools-lib/br-parser-tools/private-lex/front.rkt
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(module front mzscheme
(require (prefix is: mzlib/integer-set)
mzlib/list
syntax/stx
"util.rkt"
"stx.rkt"
"re.rkt"
"deriv.rkt")
(provide build-lexer)
(define-syntax time-label
(syntax-rules ()
((_ l e ...)
(begin
(printf "~a: " l)
(time (begin e ...))))))
;; A table is either
;; - (vector-of (union #f nat))
;; - (vector-of (vector-of (vector nat nat nat)))
(define loc:integer-set-contents is:integer-set-contents)
;; dfa->1d-table : dfa -> (same as build-lexer)
(define (dfa->1d-table dfa)
(let ((state-table (make-vector (dfa-num-states dfa) #f))
(transition-cache (make-hash-table 'equal)))
(for-each
(lambda (trans)
(let* ((from-state (car trans))
(all-chars/to (cdr trans))
(flat-all-chars/to
(sort
(apply append
(map (lambda (chars/to)
(let ((char-ranges (loc:integer-set-contents (car chars/to)))
(to (cdr chars/to)))
(map (lambda (char-range)
(let ((entry (vector (car char-range) (cdr char-range) to)))
(hash-table-get transition-cache entry
(lambda ()
(hash-table-put! transition-cache
entry
entry)
entry))))
char-ranges)))
all-chars/to))
(lambda (a b)
(< (vector-ref a 0) (vector-ref b 0))))))
(vector-set! state-table from-state (list->vector flat-all-chars/to))))
(dfa-transitions dfa))
state-table))
(define loc:foldr is:foldr)
;; dfa->2d-table : dfa -> (same as build-lexer)
(define (dfa->2d-table dfa)
(let (
;; char-table : (vector-of (union #f nat))
;; The lexer table, one entry per state per char.
;; Each entry specifies a state to transition to.
;; #f indicates no transition
(char-table (make-vector (* 256 (dfa-num-states dfa)) #f)))
;; Fill the char-table vector
(for-each
(lambda (trans)
(let ((from-state (car trans)))
(for-each (lambda (chars/to)
(let ((to-state (cdr chars/to)))
(loc:foldr (lambda (char _)
(vector-set! char-table
(bitwise-ior
char
(arithmetic-shift from-state 8))
to-state))
(void)
(car chars/to))))
(cdr trans))))
(dfa-transitions dfa))
char-table))
;; dfa->actions : dfa -> (vector-of (union #f syntax-object))
;; The action for each final state, #f if the state isn't final
(define (dfa->actions dfa)
(let ((actions (make-vector (dfa-num-states dfa) #f)))
(for-each (lambda (state/action)
(vector-set! actions (car state/action) (cdr state/action)))
(dfa-final-states/actions dfa))
actions))
;; dfa->no-look : dfa -> (vector-of bool)
;; For each state whether the lexer can ignore the next input.
;; It can do this only if there are no transitions out of the
;; current state.
(define (dfa->no-look dfa)
(let ((no-look (make-vector (dfa-num-states dfa) #t)))
(for-each (lambda (trans)
(vector-set! no-look (car trans) #f))
(dfa-transitions dfa))
no-look))
(test-block ((d1 (make-dfa 1 1 (list) (list)))
(d2 (make-dfa 4 1 (list (cons 2 2) (cons 3 3))
(list (cons 1 (list (cons (is:make-range 49 50) 1)
(cons (is:make-range 51) 2)))
(cons 2 (list (cons (is:make-range 49) 3))))))
(d3 (make-dfa 4 1 (list (cons 2 2) (cons 3 3))
(list (cons 1 (list (cons (is:make-range 100 200) 0)
(cons (is:make-range 49 50) 1)
(cons (is:make-range 51) 2)))
(cons 2 (list (cons (is:make-range 49) 3)))))))
((dfa->2d-table d1) (make-vector 256 #f))
((dfa->2d-table d2) (let ((v (make-vector 1024 #f)))
(vector-set! v 305 1)
(vector-set! v 306 1)
(vector-set! v 307 2)
(vector-set! v 561 3)
v))
((dfa->1d-table d1) (make-vector 1 #f))
((dfa->1d-table d2) #(#f
#(#(49 50 1) #(51 51 2))
#(#(49 49 3))
#f))
((dfa->1d-table d3) #(#f
#(#(49 50 1) #(51 51 2) #(100 200 0))
#(#(49 49 3))
#f))
((dfa->actions d1) (vector #f))
((dfa->actions d2) (vector #f #f 2 3))
((dfa->no-look d1) (vector #t))
((dfa->no-look d2) (vector #t #f #f #t)))
;; build-lexer : syntax-object list ->
;; (values table nat (vector-of (union #f syntax-object)) (vector-of bool) (list-of syntax-object))
;; each syntax object has the form (re action)
(define (build-lexer sos)
(let* ((disappeared-uses (box null))
(s-re-acts (map (lambda (so)
(cons (parse (stx-car so) disappeared-uses)
(stx-car (stx-cdr so))))
sos))
(cache (make-cache))
(re-acts (map (lambda (s-re-act)
(cons (->re (car s-re-act) cache)
(cdr s-re-act)))
s-re-acts))
(dfa (build-dfa re-acts cache))
(table (dfa->1d-table dfa)))
;(print-dfa dfa)
#;(let ((num-states (vector-length table))
(num-vectors (length (filter values (vector->list table))))
(num-entries (apply + (map
(lambda (x) (if x (vector-length x) 0))
(vector->list table))))
(num-different-entries
(let ((ht (make-hash-table)))
(for-each
(lambda (x)
(when x
(for-each
(lambda (y)
(hash-table-put! ht y #t))
(vector->list x))))
(vector->list table))
(length (hash-table-map ht cons)))))
(printf "~a states, ~aKB\n"
num-states
(/ (* 4.0 (+ 2 num-states (* 2 num-vectors) num-entries
(* 5 num-different-entries))) 1024)))
(values table (dfa-start-state dfa) (dfa->actions dfa) (dfa->no-look dfa)
(unbox disappeared-uses))))
)

385
br-parser-tools/br-parser-tools-lib/br-parser-tools/private-lex/re.rkt
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(module re mzscheme
(require mzlib/list
scheme/match
(prefix is: mzlib/integer-set)
"util.rkt")
(provide ->re build-epsilon build-zero build-char-set build-concat
build-repeat build-or build-and build-neg
epsilonR? zeroR? char-setR? concatR? repeatR? orR? andR? negR?
char-setR-chars concatR-re1 concatR-re2 repeatR-re repeatR-low repeatR-high
orR-res andR-res negR-re
re-nullable? re-index)
;; get-index : -> nat
(define get-index (make-counter))
;; An re is either
;; - (make-epsilonR bool nat)
;; - (make-zeroR bool nat)
;; - (make-char-setR bool nat char-set)
;; - (make-concatR bool nat re re)
;; - (make-repeatR bool nat nat nat-or-+inf.0 re)
;; - (make-orR bool nat (list-of re)) Must not directly contain any orRs
;; - (make-andR bool nat (list-of re)) Must not directly contain any andRs
;; - (make-negR bool nat re)
;;
;; Every re must have an index field globally different from all
;; other re index fields.
(define-struct re (nullable? index) (make-inspector))
(define-struct (epsilonR re) () (make-inspector))
(define-struct (zeroR re) () (make-inspector))
(define-struct (char-setR re) (chars) (make-inspector))
(define-struct (concatR re) (re1 re2) (make-inspector))
(define-struct (repeatR re) (low high re) (make-inspector))
(define-struct (orR re) (res) (make-inspector))
(define-struct (andR re) (res) (make-inspector))
(define-struct (negR re) (re) (make-inspector))
;; e : re
;; The unique epsilon re
(define e (make-epsilonR #t (get-index)))
;; z : re
;; The unique zero re
(define z (make-zeroR #f (get-index)))
;; s-re = char constant
;; | string constant (sequence of characters)
;; | re a precompiled re
;; | (repetition low high s-re) repetition between low and high times (inclusive)
;; | (union s-re ...)
;; | (intersection s-re ...)
;; | (complement s-re)
;; | (concatenation s-re ...)
;; | (char-range rng rng) match any character between two (inclusive)
;; | (char-complement char-set) match any character not listed
;; low = natural-number
;; high = natural-number or +inf.0
;; rng = char or string with length 1
;; (concatenation) (repetition 0 0 x), and "" match the empty string.
;; (union) matches no strings.
;; (intersection) matches any string.
(define loc:make-range is:make-range)
(define loc:union is:union)
(define loc:split is:split)
(define loc:complement is:complement)
;; ->re : s-re cache -> re
(define (->re exp cache)
(match exp
((? char?) (build-char-set (loc:make-range (char->integer exp)) cache))
((? string?) (->re `(concatenation ,@(string->list exp)) cache))
((? re?) exp)
(`(repetition ,low ,high ,r)
(build-repeat low high (->re r cache) cache))
(`(union ,rs ...)
(build-or (flatten-res (map (lambda (r) (->re r cache)) rs)
orR? orR-res loc:union cache)
cache))
(`(intersection ,rs ...)
(build-and (flatten-res (map (lambda (r) (->re r cache)) rs)
andR? andR-res (lambda (a b)
(let-values (((i _ __) (loc:split a b))) i))
cache)
cache))
(`(complement ,r)
(build-neg (->re r cache) cache))
(`(concatenation ,rs ...)
(foldr (lambda (x y)
(build-concat (->re x cache) y cache))
e
rs))
(`(char-range ,c1 ,c2)
(let ((i1 (char->integer (if (string? c1) (string-ref c1 0) c1)))
(i2 (char->integer (if (string? c2) (string-ref c2 0) c2))))
(if (<= i1 i2)
(build-char-set (loc:make-range i1 i2) cache)
z)))
(`(char-complement ,crs ...)
(let ((cs (->re `(union ,@crs) cache)))
(cond
((zeroR? cs) (build-char-set (loc:make-range 0 max-char-num) cache))
((char-setR? cs)
(build-char-set (loc:complement (char-setR-chars cs) 0 max-char-num) cache))
(else z))))))
;; flatten-res: (list-of re) (re -> bool) (re -> (list-of re))
;; (char-set char-set -> char-set) cache -> (list-of re)
;; Takes all the char-sets in l and combines them into one char-set using the combine function.
;; Flattens out the values of type?. get-res only needs to function on things type? returns
;; true for.
(define (flatten-res l type? get-res combine cache)
(let loop ((res l)
;; chars : (union #f char-set)
(chars #f)
(no-chars null))
(cond
((null? res)
(if chars
(cons (build-char-set chars cache) no-chars)
no-chars))
((char-setR? (car res))
(if chars
(loop (cdr res) (combine (char-setR-chars (car res)) chars) no-chars)
(loop (cdr res) (char-setR-chars (car res)) no-chars)))
((type? (car res))
(loop (append (get-res (car res)) (cdr res)) chars no-chars))
(else (loop (cdr res) chars (cons (car res) no-chars))))))
;; build-epsilon : -> re
(define (build-epsilon) e)
(define (build-zero) z)
(define loc:integer-set-contents is:integer-set-contents)
;; build-char-set : char-set cache -> re
(define (build-char-set cs cache)
(let ((l (loc:integer-set-contents cs)))
(cond
((null? l) z)
(else
(cache l
(lambda ()
(make-char-setR #f (get-index) cs)))))))
;; build-concat : re re cache -> re
(define (build-concat r1 r2 cache)
(cond
((eq? e r1) r2)
((eq? e r2) r1)
((or (eq? z r1) (eq? z r2)) z)
(else
(cache (cons 'concat (cons (re-index r1) (re-index r2)))
(lambda ()
(make-concatR (and (re-nullable? r1) (re-nullable? r2))
(get-index)
r1 r2))))))
;; build-repeat : nat nat-or-+inf.0 re cache -> re
(define (build-repeat low high r cache)
(let ((low (if (< low 0) 0 low)))
(cond
((eq? r e) e)
((and (= 0 low) (or (= 0 high) (eq? z r))) e)
((and (= 1 low) (= 1 high)) r)
((and (repeatR? r)
(eqv? (repeatR-high r) +inf.0)
(or (= 0 (repeatR-low r))
(= 1 (repeatR-low r))))
(build-repeat (* low (repeatR-low r))
+inf.0
(repeatR-re r)
cache))
(else
(cache (cons 'repeat (cons low (cons high (re-index r))))
(lambda ()
(make-repeatR (or (re-nullable? r) (= 0 low)) (get-index) low high r)))))))
;; build-or : (list-of re) cache -> re
(define (build-or rs cache)
(let ((rs
(filter
(lambda (x) (not (eq? x z)))
(do-simple-equiv (replace rs orR? orR-res null) re-index))))
(cond
((null? rs) z)
((null? (cdr rs)) (car rs))
((memq (build-neg z cache) rs) (build-neg z cache))
(else
(cache (cons 'or (map re-index rs))
(lambda ()
(make-orR (ormap re-nullable? rs) (get-index) rs)))))))
;; build-and : (list-of re) cache -> re
(define (build-and rs cache)
(let ((rs (do-simple-equiv (replace rs andR? andR-res null) re-index)))
(cond
((null? rs) (build-neg z cache))
((null? (cdr rs)) (car rs))
((memq z rs) z)
(else
(cache (cons 'and (map re-index rs))
(lambda ()
(make-andR (andmap re-nullable? rs) (get-index) rs)))))))
;; build-neg : re cache -> re
(define (build-neg r cache)
(cond
((negR? r) (negR-re r))
(else
(cache (cons 'neg (re-index r))
(lambda ()
(make-negR (not (re-nullable? r)) (get-index) r))))))
;; Tests for the build-functions
(test-block ((c (make-cache))
(isc is:integer-set-contents)
(r1 (build-char-set (is:make-range (char->integer #\1)) c))
(r2 (build-char-set (is:make-range (char->integer #\2)) c))
(r3 (build-char-set (is:make-range (char->integer #\3)) c))
(rc (build-concat r1 r2 c))
(rc2 (build-concat r2 r1 c))
(rr (build-repeat 0 +inf.0 rc c))
(ro (build-or `(,rr ,rc ,rr) c))
(ro2 (build-or `(,rc ,rr ,z) c))
(ro3 (build-or `(,rr ,rc) c))
(ro4 (build-or `(,(build-or `(,r1 ,r2) c)
,(build-or `(,r2 ,r3) c)) c))
(ra (build-and `(,rr ,rc ,rr) c))
(ra2 (build-and `(,rc ,rr) c))
(ra3 (build-and `(,rr ,rc) c))
(ra4 (build-and `(,(build-and `(,r3 ,r2) c)
,(build-and `(,r2 ,r1) c)) c))
(rn (build-neg z c))
(rn2 (build-neg r1 c)))
((isc (char-setR-chars r1)) (isc (is:make-range (char->integer #\1))))
((isc (char-setR-chars r2)) (isc (is:make-range (char->integer #\2))))
((isc (char-setR-chars r3)) (isc (is:make-range (char->integer #\3))))
((build-char-set (is:make-range) c) z)
((build-concat r1 e c) r1)
((build-concat e r1 c) r1)
((build-concat r1 z c) z)
((build-concat z r1 c) z)
((build-concat r1 r2 c) rc)
((concatR-re1 rc) r1)
((concatR-re2 rc) r2)
((concatR-re1 rc2) r2)
((concatR-re2 rc2) r1)
(ro ro2)
(ro ro3)
(ro4 (build-or `(,r1 ,r2 ,r3) c))
((orR-res ro) (list rc rr))
((orR-res ro4) (list r1 r2 r3))
((build-or null c) z)
((build-or `(,r1 ,z) c) r1)
((build-repeat 0 +inf.0 rc c) rr)
((build-repeat 0 1 z c) e)
((build-repeat 0 0 rc c) e)
((build-repeat 0 +inf.0 z c) e)
((build-repeat -1 +inf.0 z c) e)
((build-repeat 0 +inf.0 (build-repeat 0 +inf.0 rc c) c)
(build-repeat 0 +inf.0 rc c))
((build-repeat 20 20 (build-repeat 0 +inf.0 rc c) c)
(build-repeat 0 +inf.0 rc c))
((build-repeat 20 20 (build-repeat 1 +inf.0 rc c) c)
(build-repeat 20 +inf.0 rc c))
((build-repeat 1 1 rc c) rc)
((repeatR-re rr) rc)
(ra ra2)
(ra ra3)
(ra4 (build-and `(,r1 ,r2 ,r3) c))
((andR-res ra) (list rc rr))
((andR-res ra4) (list r1 r2 r3))
((build-and null c) (build-neg z c))
((build-and `(,r1 ,z) c) z)
((build-and `(,r1) c) r1)
((build-neg r1 c) (build-neg r1 c))
((build-neg (build-neg r1 c) c) r1)
((negR-re (build-neg r2 c)) r2)
((re-nullable? r1) #f)
((re-nullable? rc) #f)
((re-nullable? (build-concat rr rr c)) #t)
((re-nullable? rr) #t)
((re-nullable? (build-repeat 0 1 rc c)) #t)
((re-nullable? (build-repeat 1 2 rc c)) #f)
((re-nullable? (build-repeat 1 2 (build-or (list e r1) c) c)) #t)
((re-nullable? ro) #t)
((re-nullable? (build-or `(,r1 ,r2) c)) #f)
((re-nullable? (build-and `(,r1 ,e) c)) #f)
((re-nullable? (build-and `(,rr ,e) c)) #t)
((re-nullable? (build-neg r1 c)) #t)
((re-nullable? (build-neg rr c)) #f))
(test-block ((c (make-cache))
(isc is:integer-set-contents)
(r1 (->re #\1 c))
(r2 (->re #\2 c))
(r3-5 (->re '(char-range #\3 #\5) c))
(r4 (build-or `(,r1 ,r2) c))
(r5 (->re `(union ,r3-5 #\7) c))
(r6 (->re #\6 c)))
((flatten-res null orR? orR-res is:union c) null)
((isc (char-setR-chars (car (flatten-res `(,r1) orR? orR-res is:union c))))
(isc (is:make-range (char->integer #\1))))
((isc (char-setR-chars (car (flatten-res `(,r4) orR? orR-res is:union c))))
(isc (is:make-range (char->integer #\1) (char->integer #\2))))
((isc (char-setR-chars (car (flatten-res `(,r6 ,r5 ,r4 ,r3-5 ,r2 ,r1)
orR? orR-res is:union c))))
(isc (is:make-range (char->integer #\1) (char->integer #\7))))
((flatten-res `(,r1 ,r2) andR? andR-res (lambda (x y)
(let-values (((i _ __)
(is:split x y)))
i))
c)
(list z)))
;; ->re
(test-block ((c (make-cache))
(isc is:integer-set-contents)
(r (->re #\a c))
(rr (->re `(concatenation ,r ,r) c))
(rrr (->re `(concatenation ,r ,rr) c))
(rrr* (->re `(repetition 0 +inf.0 ,rrr) c)))
((isc (char-setR-chars r)) (isc (is:make-range (char->integer #\a))))
((->re "" c) e)
((->re "asdf" c) (->re `(concatenation #\a #\s #\d #\f) c))
((->re r c) r)
((->re `(repetition 0 +inf.0 ,r) c) (build-repeat 0 +inf.0 r c))
((->re `(repetition 1 +inf.0 ,r) c) (build-repeat 1 +inf.0 r c))
((->re `(repetition 0 1 ,r) c) (build-repeat 0 1 r c))
((->re `(repetition 0 1 ,rrr*) c) rrr*)
((->re `(union (union (char-range #\a #\c)
(char-complement (char-range #\000 #\110)
(char-range #\112 ,(integer->char max-char-num))))
(union (repetition 0 +inf.0 #\2))) c)
(build-or (list (build-char-set (is:union (is:make-range 73)
(is:make-range 97 99))
c)
(build-repeat 0 +inf.0 (build-char-set (is:make-range 50) c) c))
c))
((->re `(union ,rr ,rrr) c) (build-or (list rr rrr) c))
((->re `(union ,r) c) r)
((->re `(union) c) z)
((->re `(intersection (intersection #\111
(char-complement (char-range #\000 #\110)
(char-range #\112 ,(integer->char max-char-num))))
(intersection (repetition 0 +inf.0 #\2))) c)
(build-and (list (build-char-set (is:make-range 73) c)
(build-repeat 0 +inf.0 (build-char-set (is:make-range 50) c) c))
c))
((->re `(intersection (intersection #\000 (char-complement (char-range #\000 #\110)
(char-range #\112 ,(integer->char max-char-num))))
(intersection (repetition 0 +inf.0 #\2))) c)
z)
((->re `(intersection ,rr ,rrr) c) (build-and (list rr rrr) c))
((->re `(intersection ,r) c) r)
((->re `(intersection) c) (build-neg z c))
((->re `(complement ,r) c) (build-neg r c))
((->re `(concatenation) c) e)
((->re `(concatenation ,rrr*) c) rrr*)
(rr (build-concat r r c))
((->re `(concatenation ,r ,rr ,rrr) c)
(build-concat r (build-concat rr rrr c) c))
((isc (char-setR-chars (->re `(char-range #\1 #\1) c))) (isc (is:make-range 49)))
((isc (char-setR-chars (->re `(char-range #\1 #\9) c))) (isc (is:make-range 49 57)))
((isc (char-setR-chars (->re `(char-range "1" "1") c))) (isc (is:make-range 49)))
((isc (char-setR-chars (->re `(char-range "1" "9") c))) (isc (is:make-range 49 57)))
((->re `(char-range "9" "1") c) z)
((isc (char-setR-chars (->re `(char-complement) c)))
(isc (char-setR-chars (->re `(char-range #\000 ,(integer->char max-char-num)) c))))
((isc (char-setR-chars (->re `(char-complement #\001 (char-range #\002 ,(integer->char max-char-num))) c)))
(isc (is:make-range 0)))
)
)

220
br-parser-tools/br-parser-tools-lib/br-parser-tools/private-lex/stx.rkt
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@ -1,220 +0,0 @@
#lang racket
(require "util.rkt"
syntax/id-table)
(provide parse)
(define (bad-args stx num)
(raise-syntax-error
#f
(format "incorrect number of arguments (should have ~a)" num)
stx))
;; char-range-arg: syntax-object syntax-object -> nat
;; If c contains is a character or length 1 string, returns the integer
;; for the character. Otherwise raises a syntax error.
(define (char-range-arg stx containing-stx)
(let ((c (syntax-e stx)))
(cond
((char? c) (char->integer c))
((and (string? c) (= (string-length c) 1))
(char->integer (string-ref c 0)))
(else
(raise-syntax-error
#f
"not a char or single-char string"
containing-stx stx)))))
(module+ test
(check-equal? (char-range-arg #'#\1 #'here) (char->integer #\1))
(check-equal? (char-range-arg #'"1" #'here) (char->integer #\1)))
(define orig-insp (variable-reference->module-declaration-inspector
(#%variable-reference)))
(define (disarm stx)
(syntax-disarm stx orig-insp))
;; parse : syntax-object (box (list-of syntax-object)) -> s-re (see re.rkt)
;; checks for errors and generates the plain s-exp form for s
;; Expands lex-abbrevs and applies lex-trans.
(define (parse stx disappeared-uses)
(let loop ([stx stx]
[disappeared-uses disappeared-uses]
;; seen-lex-abbrevs: id-table
[seen-lex-abbrevs (make-immutable-free-id-table)])
(let ([recur (lambda (s)
(loop (syntax-rearm s stx)
disappeared-uses
seen-lex-abbrevs))]
[recur/abbrev (lambda (s id)
(loop (syntax-rearm s stx)
disappeared-uses
(free-id-table-set seen-lex-abbrevs id id)))])
(syntax-case (disarm stx) (repetition union intersection complement concatenation
char-range char-complement)
(_
(identifier? stx)
(let ((expansion (syntax-local-value stx (lambda () #f))))
(unless (lex-abbrev? expansion)
(raise-syntax-error 'regular-expression
"undefined abbreviation"
stx))
;; Check for cycles.
(when (free-id-table-ref seen-lex-abbrevs stx (lambda () #f))
(raise-syntax-error 'regular-expression
"illegal lex-abbrev cycle detected"
stx
#f
(list (free-id-table-ref seen-lex-abbrevs stx))))
(set-box! disappeared-uses (cons stx (unbox disappeared-uses)))
(recur/abbrev ((lex-abbrev-get-abbrev expansion)) stx)))
(_
(or (char? (syntax-e stx)) (string? (syntax-e stx)))
(syntax-e stx))
((repetition arg ...)
(let ((arg-list (syntax->list (syntax (arg ...)))))
(unless (= 3 (length arg-list))
(bad-args stx 2))
(let ((low (syntax-e (car arg-list)))
(high (syntax-e (cadr arg-list)))
(re (caddr arg-list)))
(unless (and (number? low) (exact? low) (integer? low) (>= low 0))
(raise-syntax-error #f
"not a non-negative exact integer"
stx
(car arg-list)))
(unless (or (and (number? high) (exact? high) (integer? high) (>= high 0))
(eqv? high +inf.0))
(raise-syntax-error #f
"not a non-negative exact integer or +inf.0"
stx
(cadr arg-list)))
(unless (<= low high)
(raise-syntax-error
#f
"the first argument is not less than or equal to the second argument"
stx))
`(repetition ,low ,high ,(recur re)))))
((union re ...)
`(union ,@(map recur (syntax->list (syntax (re ...))))))
((intersection re ...)
`(intersection ,@(map recur (syntax->list (syntax (re ...))))))
((complement re ...)
(let ((re-list (syntax->list (syntax (re ...)))))
(unless (= 1 (length re-list))
(bad-args stx 1))
`(complement ,(recur (car re-list)))))
((concatenation re ...)
`(concatenation ,@(map recur (syntax->list (syntax (re ...))))))
((char-range arg ...)
(let ((arg-list (syntax->list (syntax (arg ...)))))
(unless (= 2 (length arg-list))
(bad-args stx 2))
(let ((i1 (char-range-arg (car arg-list) stx))
(i2 (char-range-arg (cadr arg-list) stx)))
(if (<= i1 i2)
`(char-range ,(integer->char i1) ,(integer->char i2))
(raise-syntax-error
#f
"the first argument does not precede or equal second argument"
stx)))))
((char-complement arg ...)
(let ((arg-list (syntax->list (syntax (arg ...)))))
(unless (= 1 (length arg-list))
(bad-args stx 1))
(let ((parsed (recur (car arg-list))))
(unless (char-set? parsed)
(raise-syntax-error #f
"not a character set"
stx
(car arg-list)))
`(char-complement ,parsed))))
((op form ...)
(identifier? (syntax op))
(let* ((o (syntax op))
(expansion (syntax-local-value o (lambda () #f))))
(set-box! disappeared-uses (cons o (unbox disappeared-uses)))
(cond
((lex-trans? expansion)
(recur ((lex-trans-f expansion) (disarm stx))))
(expansion
(raise-syntax-error 'regular-expression
"not a lex-trans"
stx))
(else
(raise-syntax-error 'regular-expression
"undefined operator"
stx)))))
(_
(raise-syntax-error
'regular-expression
"not a char, string, identifier, or (op args ...)"
stx))))))
;; char-set? : s-re -> bool
;; A char-set is an re that matches only strings of length 1.
;; char-set? is conservative.
(define (char-set? s-re)
(cond
((char? s-re) #t)
((string? s-re) (= (string-length s-re) 1))
((list? s-re)
(let ((op (car s-re)))
(case op
((union intersection) (andmap char-set? (cdr s-re)))
((char-range char-complement) #t)
((repetition)
(and (= (cadr s-re) (caddr s-re)) (char-set? (cadddr s-re))))
((concatenation)
(and (= 2 (length s-re)) (char-set? (cadr s-re))))
(else #f))))
(else #f)))
(module+ test
(require rackunit))
(module+ test
(check-equal? (char-set? #\a) #t)
(check-equal? (char-set? "12") #f)
(check-equal? (char-set? "1") #t)
(check-equal? (char-set? '(repetition 1 2 #\1)) #f)
(check-equal? (char-set? '(repetition 1 1 "12")) #f)
(check-equal? (char-set? '(repetition 1 1 "1")) #t)
(check-equal? (char-set? '(union "1" "2" "3")) #t)
(check-equal? (char-set? '(union "1" "" "3")) #f)
(check-equal? (char-set? '(intersection "1" "2" (union "3" "4"))) #t)
(check-equal? (char-set? '(intersection "1" "")) #f)
(check-equal? (char-set? '(complement "1")) #f)
(check-equal? (char-set? '(concatenation "1" "2")) #f)
(check-equal? (char-set? '(concatenation "" "2")) #f)
(check-equal? (char-set? '(concatenation "1")) #t)
(check-equal? (char-set? '(concatenation "12")) #f)
(check-equal? (char-set? '(char-range #\1 #\2)) #t)
(check-equal? (char-set? '(char-complement #\1)) #t))
;; yikes... these test cases all have the wrong arity, now.
;; and by "now", I mean it's been broken since before we
;; moved to git.
(module+ test
(check-equal? (parse #'#\a null) #\a)
(check-equal? (parse #'"1" null) "1")
(check-equal? (parse #'(repetition 1 1 #\1) null)
'(repetition 1 1 #\1))
(check-equal? (parse #'(repetition 0 +inf.0 #\1) null) '(repetition 0 +inf.0 #\1))
(check-equal? (parse #'(union #\1 (union "2") (union)) null)
'(union #\1 (union "2") (union)))
(check-equal? (parse #'(intersection #\1 (intersection "2") (intersection))
null)
'(intersection #\1 (intersection "2") (intersection)))
(check-equal? (parse #'(complement (union #\1 #\2))
null)
'(complement (union #\1 #\2)))
(check-equal? (parse #'(concatenation "1" "2" (concatenation)) null)
'(concatenation "1" "2" (concatenation)))
(check-equal? (parse #'(char-range "1" #\1) null) '(char-range #\1 #\1))
(check-equal? (parse #'(char-range #\1 "1") null) '(char-range #\1 #\1))
(check-equal? (parse #'(char-range "1" "3") null) '(char-range #\1 #\3))
(check-equal? (parse #'(char-complement (union "1" "2")) null)
'(char-complement (union "1" "2"))))
; )

9
br-parser-tools/br-parser-tools-lib/br-parser-tools/private-lex/token-syntax.rkt
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(module token-syntax mzscheme
;; The things needed at compile time to handle definition of tokens
(provide make-terminals-def terminals-def-t terminals-def?
make-e-terminals-def e-terminals-def-t e-terminals-def?)
(define-struct terminals-def (t))
(define-struct e-terminals-def (t))
)

92
br-parser-tools/br-parser-tools-lib/br-parser-tools/private-lex/token.rkt
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(module token mzscheme
(require-for-syntax "token-syntax.rkt")
;; Defining tokens
(provide define-tokens define-empty-tokens make-token token?
(protect (rename token-name real-token-name))
(protect (rename token-value real-token-value))
(rename token-name* token-name)
(rename token-value* token-value)
(struct position (offset line col))
(struct position-token (token start-pos end-pos))
(struct srcloc-token (token srcloc)))
;; A token is either
;; - symbol
;; - (make-token symbol any)
(define-struct token (name value) (make-inspector))
;; token-name*: token -> symbol
(define (token-name* t)
(cond
((symbol? t) t)
((token? t) (token-name t))
(else (raise-type-error
'token-name
"symbol or struct:token"
0
t))))
;; token-value*: token -> any
(define (token-value* t)
(cond
((symbol? t) #f)
((token? t) (token-value t))
(else (raise-type-error
'token-value
"symbol or struct:token"
0
t))))
(define-for-syntax (make-ctor-name n)
(datum->syntax-object n
(string->symbol (format "token-~a" (syntax-e n)))
n
n))
(define-for-syntax (make-define-tokens empty?)
(lambda (stx)
(syntax-case stx ()
((_ name (token ...))
(andmap identifier? (syntax->list (syntax (token ...))))
(with-syntax (((marked-token ...)
(map values #;(make-syntax-introducer)
(syntax->list (syntax (token ...))))))
(quasisyntax/loc stx
(begin
(define-syntax name
#,(if empty?
#'(make-e-terminals-def (quote-syntax (marked-token ...)))
#'(make-terminals-def (quote-syntax (marked-token ...)))))
#,@(map
(lambda (n)
(when (eq? (syntax-e n) 'error)
(raise-syntax-error
#f
"Cannot define a token named error."
stx))
(if empty?
#`(define (#,(make-ctor-name n))
'#,n)
#`(define (#,(make-ctor-name n) x)
(make-token '#,n x))))
(syntax->list (syntax (token ...))))
#;(define marked-token #f) #;...))))
((_ ...)
(raise-syntax-error
#f
"must have the form (define-tokens name (identifier ...)) or (define-empty-tokens name (identifier ...))"
stx)))))
(define-syntax define-tokens (make-define-tokens #f))
(define-syntax define-empty-tokens (make-define-tokens #t))
(define-struct position (offset line col) #f)
(define-struct position-token (token start-pos end-pos) #f)
(define-struct srcloc-token (token srcloc) #f)
)

69
br-parser-tools/br-parser-tools-lib/br-parser-tools/private-lex/unicode-chars.rkt
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#lang racket
(require "util.rkt")
(provide (all-defined-out))
;; mapped-chars : (listof (list nat nat bool))
(define mapped-chars (make-known-char-range-list))
;; get-chars-for-x : (nat -> bool) (listof (list nat nat bool)) -> (listof (cons nat nat))
(define (get-chars-for char-x? mapped-chars)
(cond
((null? mapped-chars) null)
(else
(let* ((range (car mapped-chars))
(low (car range))
(high (cadr range))
(x (char-x? low)))
(cond
((caddr range)
(if x
(cons (cons low high)
(get-chars-for char-x? (cdr mapped-chars)))
(get-chars-for char-x? (cdr mapped-chars))))
(else
(let loop ((range-start low)
(i (car range))
(parity x))
(cond
((> i high)
(if parity
(cons (cons range-start high) (get-chars-for char-x? (cdr mapped-chars)))
(get-chars-for char-x? (cdr mapped-chars))))
((eq? parity (char-x? i))
(loop range-start (add1 i) parity))
(parity
(cons (cons range-start (sub1 i)) (loop i (add1 i) #f)))
(else
(loop i (add1 i) #t))))))))))
(define (compute-ranges x?)
(delay (get-chars-for (lambda (x) (x? (integer->char x))) mapped-chars)))
(define alphabetic-ranges (compute-ranges char-alphabetic?)) ;; 325
(define lower-case-ranges (compute-ranges char-lower-case?)) ;; 405
(define upper-case-ranges (compute-ranges char-upper-case?)) ;; 380
(define title-case-ranges (compute-ranges char-title-case?)) ;; 10
(define numeric-ranges (compute-ranges char-numeric?)) ;; 47
(define symbolic-ranges (compute-ranges char-symbolic?)) ;; 153
(define punctuation-ranges (compute-ranges char-punctuation?)) ;; 86
(define graphic-ranges (compute-ranges char-graphic?)) ;; 401
(define whitespace-ranges (compute-ranges char-whitespace?)) ;; 10
(define blank-ranges (compute-ranges char-blank?)) ;; 9
#;(define hexadecimal-ranges (compute-ranges char-hexadecimal?))
(define iso-control-ranges (compute-ranges char-iso-control?)) ;; 2
(module+ test
(require rackunit)
(check-equal? (get-chars-for odd? '()) '())
(check-equal? (get-chars-for odd? '((1 4 #f) (8 13 #f)))
'((1 . 1) (3 . 3) (9 . 9) (11 . 11) (13 . 13)))
(check-equal? (get-chars-for (lambda (x)
(odd? (quotient x 10)))
'((1 5 #t) (17 19 #t) (21 51 #f)))
'((17 . 19) (30 . 39) (50 . 51))))

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br-parser-tools/br-parser-tools-lib/br-parser-tools/private-lex/util.rkt
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#lang racket
(provide (all-defined-out))
(define max-char-num #x10FFFF)
(define-struct lex-abbrev (get-abbrev))
(define-struct lex-trans (f))
(module+ test
(require rackunit))
#;(define-syntax test-block
(syntax-rules ()
((_ defs (code right-ans) ...)
(let* defs
(let ((real-ans code))
(unless (equal? real-ans right-ans)
(printf "Test failed: ~e gave ~e. Expected ~e\n"
'code real-ans 'right-ans))) ...))))
(define-syntax test-block
(syntax-rules ()
((_ x ...) (void))))
;; A cache is (X ( -> Y) -> Y)
;; make-cache : -> cache
;; table map Xs to Ys. If key is mapped, its value is returned.
;; Otherwise, build is invoked and its result is placed in the table and
;; returned.
;; Xs are compared with equal?
(define (make-cache)
(let ((table (make-hash)))
(lambda (key build)
(hash-ref table key
(lambda ()
(let ((new (build)))
(hash-set! table key new)
new))))))
(module+ test
(define cache (make-cache))
(check-equal? (cache '(s 1 2) (lambda () 9)) 9)
(check-equal? (cache '(s 2 1) (lambda () 8)) 8)
(check-equal? (cache '(s 1 2) (lambda () 1)) 9)
(check-equal? (cache (cons 's (cons 0 (cons +inf.0 10)))
(lambda () 22)) 22)
(check-equal? (cache (cons 's (cons 0 (cons +inf.0 10)))
(lambda () 1)) 22))
;; make-counter : -> -> nat
;; makes a function that returns a higher number by 1, each time
;; it is called.
(define (make-counter)
(let ((counter 0))
(lambda ()
(begin0
counter
(set! counter (add1 counter))))))
(module+ test
(define c (make-counter))
(define d (make-counter))
(check-equal? (c) 0)
(check-equal? (d) 0)
(check-equal? (c) 1)
(check-equal? (d) 1)
(check-equal? (c) 2))
;; remove-dups : (list-of X) (X -> number) -> (list-of X)
;; removes the entries from l that have the same index as a
;; previous entry. l must be grouped by indexes.
(define (remove-dups l index acc)
(cond
((null? l) (reverse acc))
((null? acc) (remove-dups (cdr l) index (cons (car l) acc)))
((= (index (car acc)) (index (car l)))
(remove-dups (cdr l) index acc))
(else
(remove-dups (cdr l) index (cons (car l) acc)))))
(module+ test
(check-equal? (remove-dups '((1 2) (2 2) (1 3) (1 4)
(100 4) (0 5)) cadr null)
'((1 2) (1 3) (1 4) (0 5)))
(check-equal? (remove-dups null error null) null))
;; do-simple-equiv : (list-of X) (X -> nat) -> (list-of X)
;; Sorts l according to index and removes the entries with duplicate
;; indexes.
(define (do-simple-equiv l index)
(let ((ordered (sort l (lambda (a b) (< (index a) (index b))))))
(remove-dups ordered index null)))
(module+ test
(check-equal? (do-simple-equiv '((2 2) (1 4) (1 2)
(100 4) (1 3) (0 5))
cadr)
'((2 2) (1 3) (1 4) (0 5)))
(check-equal? (do-simple-equiv null error) null))
;; replace : (list-of X) (X -> bool) (X -> (list-of X)) (list-of X) ->
;; (list-of X)
;; If (pred? r) for some r in l, splice (get r) in place of r in the resulting
;; list.
(define (replace l pred? get acc)
(cond
((null? l) acc)
((pred? (car l)) (replace (cdr l) pred? get (append (get (car l)) acc)))
(else (replace (cdr l) pred? get (cons (car l) acc)))))
(module+ test
(check-equal? (replace null void (lambda () (list 1)) null) null)
(check-equal? (replace '(1 2 3 4 3 5)
(lambda (x) (= x 3))
(lambda (x) (list 1 2 3))
null)
'(5 1 2 3 4 1 2 3 2 1)))

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br-parser-tools/br-parser-tools-lib/br-parser-tools/private-yacc/grammar.rkt
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;; Constructs to create and access grammars, the internal
;; representation of the input to the parser generator.
(module grammar mzscheme
(require mzlib/class
mzlib/list
"yacc-helper.rkt"
racket/contract)
;; Each production has a unique index 0 <= index <= number of productions
(define-struct prod (lhs rhs index prec action) (make-inspector))
;; The dot-pos field is the index of the element in the rhs
;; of prod that the dot immediately precedes.
;; Thus 0 <= dot-pos <= (vector-length rhs).
(define-struct item (prod dot-pos) (make-inspector))
;; gram-sym = (union term? non-term?)
;; Each term has a unique index 0 <= index < number of terms
;; Each non-term has a unique index 0 <= index < number of non-terms
(define-struct term (sym index prec) (make-inspector))
(define-struct non-term (sym index) (make-inspector))
;; a precedence declaration.
(define-struct prec (num assoc) (make-inspector))
(provide/contract
(make-item (prod? (or/c #f natural-number/c) . -> . item?))
(make-term (symbol? (or/c #f natural-number/c) (or/c prec? #f) . -> . term?))
(make-non-term (symbol? (or/c #f natural-number/c) . -> . non-term?))
(make-prec (natural-number/c (or/c 'left 'right 'nonassoc) . -> . prec?))
(make-prod (non-term? (vectorof (or/c non-term? term?))
(or/c #f natural-number/c) (or/c #f prec?) syntax? . -> . prod?)))
(provide
;; Things that work on items
start-item? item-prod item->string
sym-at-dot move-dot-right item<? item-dot-pos
;; Things that operate on grammar symbols
gram-sym-symbol gram-sym-index term-prec gram-sym->string
non-term? term? non-term<? term<?
term-list->bit-vector term-index non-term-index
;; Things that work on precs
prec-num prec-assoc
grammar%
;; Things that work on productions
prod-index prod-prec prod-rhs prod-lhs prod-action)
;;---------------------- LR items --------------------------
;; item<?: LR-item * LR-item -> bool
;; Lexicographic comparison on two items.
(define (item<? i1 i2)
(let ((p1 (prod-index (item-prod i1)))
(p2 (prod-index (item-prod i2))))
(or (< p1 p2)
(and (= p1 p2)
(let ((d1 (item-dot-pos i1))
(d2 (item-dot-pos i2)))
(< d1 d2))))))
;; start-item?: LR-item -> bool
;; The start production always has index 0
(define (start-item? i)
(= 0 (non-term-index (prod-lhs (item-prod i)))))
;; move-dot-right: LR-item -> LR-item | #f
;; moves the dot to the right in the item, unless it is at its
;; rightmost, then it returns false
(define (move-dot-right i)
(cond
((= (item-dot-pos i) (vector-length (prod-rhs (item-prod i)))) #f)
(else (make-item (item-prod i)
(add1 (item-dot-pos i))))))
;; sym-at-dot: LR-item -> gram-sym | #f
;; returns the symbol after the dot in the item or #f if there is none
(define (sym-at-dot i)
(let ((dp (item-dot-pos i))
(rhs (prod-rhs (item-prod i))))
(cond
((= dp (vector-length rhs)) #f)
(else (vector-ref rhs dp)))))
;; print-item: LR-item ->
(define (item->string it)
(let ((print-sym (lambda (i)
(let ((gs (vector-ref (prod-rhs (item-prod it)) i)))
(cond
((term? gs) (format "~a " (term-sym gs)))
(else (format "~a " (non-term-sym gs))))))))
(string-append
(format "~a -> " (non-term-sym (prod-lhs (item-prod it))))
(let loop ((i 0))
(cond
((= i (vector-length (prod-rhs (item-prod it))))
(if (= i (item-dot-pos it))
". "
""))
((= i (item-dot-pos it))
(string-append ". " (print-sym i) (loop (add1 i))))
(else (string-append (print-sym i) (loop (add1 i)))))))))
;; --------------------- Grammar Symbols --------------------------
(define (non-term<? nt1 nt2)
(< (non-term-index nt1) (non-term-index nt2)))
(define (term<? nt1 nt2)
(< (term-index nt1) (term-index nt2)))
(define (gram-sym-index gs)
(cond
((term? gs) (term-index gs))
(else (non-term-index gs))))
(define (gram-sym-symbol gs)
(cond
((term? gs) (term-sym gs))
(else (non-term-sym gs))))
(define (gram-sym->string gs)
(symbol->string (gram-sym-symbol gs)))
;; term-list->bit-vector: term list -> int
;; Creates a number where the nth bit is 1 if the term with index n is in
;; the list, and whose nth bit is 0 otherwise
(define (term-list->bit-vector terms)
(cond
((null? terms) 0)
(else
(bitwise-ior (arithmetic-shift 1 (term-index (car terms))) (term-list->bit-vector (cdr terms))))))
;; ------------------------- Grammar ------------------------------
(define grammar%
(class object%
(super-instantiate ())
;; prods: production list list
;; where there is one production list per non-term
(init prods)
;; init-prods: production list
;; The productions parsing can start from
;; nullable-non-terms is indexed by the non-term-index and is true iff non-term is nullable
(init-field init-prods terms non-terms end-terms)
;; list of all productions
(define all-prods (apply append prods))
(define num-prods (length all-prods))
(define num-terms (length terms))
(define num-non-terms (length non-terms))
(let ((count 0))
(for-each
(lambda (nt)
(set-non-term-index! nt count)
(set! count (add1 count)))
non-terms))
(let ((count 0))
(for-each
(lambda (t)
(set-term-index! t count)
(set! count (add1 count)))
terms))
(let ((count 0))
(for-each
(lambda (prod)
(set-prod-index! prod count)
(set! count (add1 count)))
all-prods))
;; indexed by the index of the non-term - contains the list of productions for that non-term
(define nt->prods
(let ((v (make-vector (length prods) #f)))
(for-each (lambda (prods)
(vector-set! v (non-term-index (prod-lhs (car prods))) prods))
prods)
v))
(define nullable-non-terms
(nullable all-prods num-non-terms))
(define/public (get-num-terms) num-terms)
(define/public (get-num-non-terms) num-non-terms)
(define/public (get-prods-for-non-term nt)
(vector-ref nt->prods (non-term-index nt)))
(define/public (get-prods) all-prods)
(define/public (get-init-prods) init-prods)
(define/public (get-terms) terms)
(define/public (get-non-terms) non-terms)
(define/public (get-num-prods) num-prods)
(define/public (get-end-terms) end-terms)
(define/public (nullable-non-term? nt)
(vector-ref nullable-non-terms (non-term-index nt)))
(define/public (nullable-after-dot? item)
(let* ((rhs (prod-rhs (item-prod item)))
(prod-length (vector-length rhs)))
(let loop ((i (item-dot-pos item)))
(cond
((< i prod-length)
(if (and (non-term? (vector-ref rhs i)) (nullable-non-term? (vector-ref rhs i)))
(loop (add1 i))
#f))
((= i prod-length) #t)))))
(define/public (nullable-non-term-thunk)
(lambda (nt)
(nullable-non-term? nt)))
(define/public (nullable-after-dot?-thunk)
(lambda (item)
(nullable-after-dot? item)))))
;; nullable: production list * int -> non-term set
;; determines which non-terminals can derive epsilon
(define (nullable prods num-nts)
(letrec ((nullable (make-vector num-nts #f))
(added #f)
;; possible-nullable: producion list -> production list
;; Removes all productions that have a terminal
(possible-nullable
(lambda (prods)
(filter (lambda (prod)
(vector-andmap non-term? (prod-rhs prod)))
prods)))
;; set-nullables: production list -> production list
;; makes one pass through the productions, adding the ones
;; known to be nullable now to nullable and returning a list
;; of productions that we don't know about yet.
(set-nullables
(lambda (prods)
(cond
((null? prods) null)
((vector-ref nullable
(gram-sym-index (prod-lhs (car prods))))
(set-nullables (cdr prods)))
((vector-andmap (lambda (nt)
(vector-ref nullable (gram-sym-index nt)))
(prod-rhs (car prods)))
(vector-set! nullable
(gram-sym-index (prod-lhs (car prods)))
#t)
(set! added #t)
(set-nullables (cdr prods)))
(else
(cons (car prods)
(set-nullables (cdr prods))))))))
(let loop ((P (possible-nullable prods)))
(cond
((null? P) nullable)
(else
(set! added #f)
(let ((new-P (set-nullables P)))
(if added
(loop new-P)
nullable)))))))
)

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br-parser-tools/br-parser-tools-lib/br-parser-tools/private-yacc/graph.rkt
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(module graph mzscheme
(provide digraph)
(define (zero-thunk) 0)
;; digraph:
;; ('a list) * ('a -> 'a list) * ('a -> 'b) * ('b * 'b -> 'b) * (-> 'b)
;; -> ('a -> 'b)
;; DeRemer and Pennello 1982
;; Computes (f x) = (f- x) union Union{(f y) | y in (edges x)}
;; We use a hash-table to represent the result function 'a -> 'b set, so
;; the values of type 'a must be comparable with eq?.
(define (digraph nodes edges f- union fail)
(letrec [
;; Will map elements of 'a to 'b sets
(results (make-hash-table))
(f (lambda (x) (hash-table-get results x fail)))
;; Maps elements of 'a to integers.
(N (make-hash-table))
(get-N (lambda (x) (hash-table-get N x zero-thunk)))
(set-N (lambda (x d) (hash-table-put! N x d)))
(stack null)
(push (lambda (x)
(set! stack (cons x stack))))
(pop (lambda ()
(begin0
(car stack)
(set! stack (cdr stack)))))
(depth (lambda () (length stack)))
;; traverse: 'a ->
(traverse
(lambda (x)
(push x)
(let ((d (depth)))
(set-N x d)
(hash-table-put! results x (f- x))
(for-each (lambda (y)
(if (= 0 (get-N y))
(traverse y))
(hash-table-put! results
x
(union (f x) (f y)))
(set-N x (min (get-N x) (get-N y))))
(edges x))
(if (= d (get-N x))
(let loop ((p (pop)))
(set-N p +inf.0)
(hash-table-put! results p (f x))
(if (not (eq? x p))
(loop (pop))))))))]
(for-each (lambda (x)
(if (= 0 (get-N x))
(traverse x)))
nodes)
f))
)

374
br-parser-tools/br-parser-tools-lib/br-parser-tools/private-yacc/input-file-parser.rkt
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(module input-file-parser mzscheme
;; routines for parsing the input to the parser generator and producing a
;; grammar (See grammar.rkt)
(require "yacc-helper.rkt"
"../private-lex/token-syntax.rkt"
"grammar.rkt"
mzlib/class
racket/contract)
(require-for-template mzscheme)
(define (is-a-grammar%? x) (is-a? x grammar%))
(provide/contract
(parse-input ((listof identifier?) (listof identifier?) (listof identifier?)
(or/c #f syntax?) syntax? any/c . -> . is-a-grammar%?))
(get-term-list ((listof identifier?) . -> . (listof identifier?))))
(define stx-for-original-property (read-syntax #f (open-input-string "original")))
;; get-args: ??? -> (values (listof syntax) (or/c #f (cons integer? stx)))
(define (get-args i rhs src-pos term-defs)
(let ((empty-table (make-hash-table))
(biggest-pos #f))
(hash-table-put! empty-table 'error #t)
(for-each (lambda (td)
(let ((v (syntax-local-value td)))
(if (e-terminals-def? v)
(for-each (lambda (s)
(hash-table-put! empty-table (syntax-object->datum s) #t))
(syntax->list (e-terminals-def-t v))))))
term-defs)
(let ([args
(let get-args ((i i)
(rhs rhs))
(cond
((null? rhs) null)
(else
(let ((b (car rhs))
(name (if (hash-table-get empty-table (syntax-object->datum (car rhs)) (lambda () #f))
(gensym)
(string->symbol (format "$~a" i)))))
(cond
(src-pos
(let ([start-pos-id
(datum->syntax-object b (string->symbol (format "$~a-start-pos" i)) b stx-for-original-property)]
[end-pos-id
(datum->syntax-object b (string->symbol (format "$~a-end-pos" i)) b stx-for-original-property)])
(set! biggest-pos (cons start-pos-id end-pos-id))
`(,(datum->syntax-object b name b stx-for-original-property)
,start-pos-id
,end-pos-id
,@(get-args (add1 i) (cdr rhs)))))
(else
`(,(datum->syntax-object b name b stx-for-original-property)
,@(get-args (add1 i) (cdr rhs)))))))))])
(values args biggest-pos))))
;; Given the list of terminal symbols and the precedence/associativity definitions,
;; builds terminal structures (See grammar.rkt)
;; build-terms: symbol list * symbol list list -> term list
(define (build-terms term-list precs)
(let ((counter 0)
;;(term-list (cons (gensym) term-list))
;; Will map a terminal symbol to its precedence/associativity
(prec-table (make-hash-table)))
;; Fill the prec table
(for-each
(lambda (p-decl)
(begin0
(let ((assoc (car p-decl)))
(for-each
(lambda (term-sym)
(hash-table-put! prec-table term-sym (make-prec counter assoc)))
(cdr p-decl)))
(set! counter (add1 counter))))
precs)
;; Build the terminal structures
(map
(lambda (term-sym)
(make-term term-sym
#f
(hash-table-get prec-table term-sym (lambda () #f))))
term-list)))
;; Retrieves the terminal symbols from a terminals-def (See terminal-syntax.rkt)
;; get-terms-from-def: identifier? -> (listof identifier?)
(define (get-terms-from-def term-syn)
(let ((t (syntax-local-value term-syn (lambda () #f))))
(cond
((terminals-def? t) (syntax->list (terminals-def-t t)))
((e-terminals-def? t) (syntax->list (e-terminals-def-t t)))
(else
(raise-syntax-error
'parser-tokens
"undefined token group"
term-syn)))))
(define (get-term-list term-group-names)
(remove-duplicates
(cons (datum->syntax-object #f 'error)
(apply append
(map get-terms-from-def term-group-names)))))
(define (parse-input term-defs start ends prec-decls prods src-pos)
(let* ((start-syms (map syntax-e start))
(list-of-terms (map syntax-e (get-term-list term-defs)))
(end-terms
(map
(lambda (end)
(unless (memq (syntax-e end) list-of-terms)
(raise-syntax-error
'parser-end-tokens
(format "End token ~a not defined as a token"
(syntax-e end))
end))
(syntax-e end))
ends))
;; Get the list of terminals out of input-terms
(list-of-non-terms
(syntax-case prods ()
(((non-term production ...) ...)
(begin
(for-each
(lambda (nts)
(if (memq (syntax-object->datum nts) list-of-terms)
(raise-syntax-error
'parser-non-terminals
(format "~a used as both token and non-terminal"
(syntax-object->datum nts))
nts)))
(syntax->list (syntax (non-term ...))))
(let ((dup (duplicate-list? (syntax-object->datum
(syntax (non-term ...))))))
(if dup
(raise-syntax-error
'parser-non-terminals
(format "non-terminal ~a defined multiple times"
dup)
prods)))
(syntax-object->datum (syntax (non-term ...)))))
(_
(raise-syntax-error
'parser-grammar
"Grammar must be of the form (grammar (non-terminal productions ...) ...)"
prods))))
;; Check the precedence declarations for errors and turn them into data
(precs
(syntax-case prec-decls ()
(((type term ...) ...)
(let ((p-terms
(syntax-object->datum (syntax (term ... ...)))))
(cond
((duplicate-list? p-terms) =>
(lambda (d)
(raise-syntax-error
'parser-precedences
(format "duplicate precedence declaration for token ~a"
d)
prec-decls)))
(else
(for-each
(lambda (a)
(for-each
(lambda (t)
(if (not (memq (syntax-object->datum t)
list-of-terms))
(raise-syntax-error
'parser-precedences
(format
"Precedence declared for non-token ~a"
(syntax-object->datum t))
t)))
(syntax->list a)))
(syntax->list (syntax ((term ...) ...))))
(for-each
(lambda (type)
(if (not (memq (syntax-object->datum type)
`(left right nonassoc)))
(raise-syntax-error
'parser-precedences
"Associativity must be left, right or nonassoc"
type)))
(syntax->list (syntax (type ...))))
(syntax-object->datum prec-decls)))))
(#f null)
(_
(raise-syntax-error
'parser-precedences
"Precedence declaration must be of the form (precs (assoc term ...) ...) where assoc is left, right or nonassoc"
prec-decls))))
(terms (build-terms list-of-terms precs))
(non-terms (map (lambda (non-term) (make-non-term non-term #f))
list-of-non-terms))
(term-table (make-hash-table))
(non-term-table (make-hash-table)))
(for-each (lambda (t)
(hash-table-put! term-table (gram-sym-symbol t) t))
terms)
(for-each (lambda (nt)
(hash-table-put! non-term-table (gram-sym-symbol nt) nt))
non-terms)
(let* (
;; parse-prod: syntax-object -> gram-sym vector
(parse-prod
(lambda (prod-so)
(syntax-case prod-so ()
((prod-rhs-sym ...)
(andmap identifier? (syntax->list prod-so))
(begin
(for-each (lambda (t)
(if (memq (syntax-object->datum t) end-terms)
(raise-syntax-error
'parser-production-rhs
(format "~a is an end token and cannot be used in a production"
(syntax-object->datum t))
t)))
(syntax->list prod-so))
(list->vector
(map (lambda (s)
(hash-table-get
term-table
(syntax-object->datum s)
(lambda ()
(hash-table-get
non-term-table
(syntax-object->datum s)
(lambda ()
(raise-syntax-error
'parser-production-rhs
(format
"~a is not declared as a terminal or non-terminal"
(syntax-object->datum s))
s))))))
(syntax->list prod-so)))))
(_
(raise-syntax-error
'parser-production-rhs
"production right-hand-side must have form (symbol ...)"
prod-so)))))
;; parse-action: syntax-object * syntax-object -> syntax-object
(parse-action
(lambda (rhs act)
(let-values ([(args biggest) (get-args 1 (syntax->list rhs) src-pos term-defs)])
(let ([act
(if biggest
(with-syntax ([$n-start-pos (datum->syntax-object (car biggest) '$n-start-pos)]
[$n-end-pos (datum->syntax-object (cdr biggest) '$n-end-pos)])
#`(let ([$n-start-pos #,(car biggest)]
[$n-end-pos #,(cdr biggest)])
#,act))
act)])
(quasisyntax/loc act
(lambda #,args
#,act))))))
;; parse-prod+action: non-term * syntax-object -> production
(parse-prod+action
(lambda (nt prod-so)
(syntax-case prod-so ()
((prod-rhs action)
(let ((p (parse-prod (syntax prod-rhs))))
(make-prod
nt
p
#f
(let loop ((i (sub1 (vector-length p))))
(if (>= i 0)
(let ((gs (vector-ref p i)))
(if (term? gs)
(term-prec gs)
(loop (sub1 i))))
#f))
(parse-action (syntax prod-rhs) (syntax action)))))
((prod-rhs (prec term) action)
(identifier? (syntax term))
(let ((p (parse-prod (syntax prod-rhs))))
(make-prod
nt
p
#f
(term-prec
(hash-table-get
term-table
(syntax-object->datum (syntax term))
(lambda ()
(raise-syntax-error
'parser-production-rhs
(format
"unrecognized terminal ~a in precedence declaration"
(syntax-object->datum (syntax term)))
(syntax term)))))
(parse-action (syntax prod-rhs) (syntax action)))))
(_
(raise-syntax-error
'parser-production-rhs
"production must have form [(symbol ...) expression] or [(symbol ...) (prec symbol) expression]"
prod-so)))))
;; parse-prod-for-nt: syntax-object -> production list
(parse-prods-for-nt
(lambda (prods-so)
(syntax-case prods-so ()
((nt productions ...)
(> (length (syntax->list (syntax (productions ...)))) 0)
(let ((nt (hash-table-get non-term-table
(syntax-object->datum (syntax nt)))))
(map (lambda (p) (parse-prod+action nt p))
(syntax->list (syntax (productions ...))))))
(_
(raise-syntax-error
'parser-productions
"A production for a non-terminal must be (non-term right-hand-side ...) with at least 1 right hand side"
prods-so))))))
(for-each
(lambda (sstx ssym)
(unless (memq ssym list-of-non-terms)
(raise-syntax-error
'parser-start
(format "Start symbol ~a not defined as a non-terminal" ssym)
sstx)))
start start-syms)
(let* ((starts (map (lambda (x) (make-non-term (gensym) #f)) start-syms))
(end-non-terms (map (lambda (x) (make-non-term (gensym) #f)) start-syms))
(parsed-prods (map parse-prods-for-nt (syntax->list prods)))
(start-prods
(map (lambda (start end-non-term)
(list (make-prod start (vector end-non-term) #f #f
(syntax (lambda (x) x)))))
starts end-non-terms))
(prods
`(,@start-prods
,@(map
(lambda (end-nt start-sym)
(map
(lambda (end)
(make-prod end-nt
(vector
(hash-table-get non-term-table start-sym)
(hash-table-get term-table end))
#f
#f
(syntax (lambda (x) x))))
end-terms))
end-non-terms start-syms)
,@parsed-prods)))
(make-object grammar%
prods
(map car start-prods)
terms
(append starts (append end-non-terms non-terms))
(map (lambda (term-name)
(hash-table-get term-table term-name))
end-terms)))))))

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br-parser-tools/br-parser-tools-lib/br-parser-tools/private-yacc/lalr.rkt
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(module lalr mzscheme
;; Compute LALR lookaheads from DeRemer and Pennello 1982
(require "lr0.rkt"
"grammar.rkt"
mzlib/list
mzlib/class)
(provide compute-LA)
;; compute-DR: LR0-automaton * grammar -> (trans-key -> term set)
;; computes for each state, non-term transition pair, the terminals
;; which can transition out of the resulting state
;; output term set is represented in bit-vector form
(define (compute-DR a g)
(lambda (tk)
(let ((r (send a run-automaton (trans-key-st tk) (trans-key-gs tk))))
(term-list->bit-vector
(filter
(lambda (term)
(send a run-automaton r term))
(send g get-terms))))))
;; compute-reads:
;; LR0-automaton * grammar -> (trans-key -> trans-key list)
(define (compute-reads a g)
(let ((nullable-non-terms
(filter (lambda (nt) (send g nullable-non-term? nt))
(send g get-non-terms))))
(lambda (tk)
(let ((r (send a run-automaton (trans-key-st tk) (trans-key-gs tk))))
(map (lambda (x) (make-trans-key r x))
(filter (lambda (non-term) (send a run-automaton r non-term))
nullable-non-terms))))))
;; compute-read: LR0-automaton * grammar -> (trans-key -> term set)
;; output term set is represented in bit-vector form
(define (compute-read a g)
(let* ((dr (compute-DR a g))
(reads (compute-reads a g)))
(digraph-tk->terml (send a get-mapped-non-term-keys)
reads
dr
(send a get-num-states))))
;; returns the list of all k such that state k transitions to state start on the
;; transitions in rhs (in order)
(define (run-lr0-backward a rhs dot-pos start num-states)
(let loop ((states (list start))
(i (sub1 dot-pos)))
(cond
((< i 0) states)
(else (loop (send a run-automaton-back states (vector-ref rhs i))
(sub1 i))))))
;; prod->items-for-include: grammar * prod * non-term -> lr0-item list
;; returns the list of all (B -> beta . nt gamma) such that prod = (B -> beta nt gamma)
;; and gamma =>* epsilon
(define (prod->items-for-include g prod nt)
(let* ((rhs (prod-rhs prod))
(rhs-l (vector-length rhs)))
(append (if (and (> rhs-l 0) (eq? nt (vector-ref rhs (sub1 rhs-l))))
(list (make-item prod (sub1 rhs-l)))
null)
(let loop ((i (sub1 rhs-l)))
(cond
((and (> i 0)
(non-term? (vector-ref rhs i))
(send g nullable-non-term? (vector-ref rhs i)))
(if (eq? nt (vector-ref rhs (sub1 i)))
(cons (make-item prod (sub1 i))
(loop (sub1 i)))
(loop (sub1 i))))
(else null))))))
;; prod-list->items-for-include: grammar * prod list * non-term -> lr0-item list
;; return the list of all (B -> beta . nt gamma) such that (B -> beta nt gamma) in prod-list
;; and gamma =>* epsilon
(define (prod-list->items-for-include g prod-list nt)
(apply append (map (lambda (prod) (prod->items-for-include g prod nt)) prod-list)))
;; comput-includes: lr0-automaton * grammar -> (trans-key -> trans-key list)
(define (compute-includes a g)
(let ((num-states (send a get-num-states))
(items-for-input-nt (make-vector (send g get-num-non-terms) null)))
(for-each
(lambda (input-nt)
(vector-set! items-for-input-nt (non-term-index input-nt)
(prod-list->items-for-include g (send g get-prods) input-nt)))
(send g get-non-terms))
(lambda (tk)
(let* ((goal-state (trans-key-st tk))
(non-term (trans-key-gs tk))
(items (vector-ref items-for-input-nt (non-term-index non-term))))
(trans-key-list-remove-dups
(apply append
(map (lambda (item)
(let* ((prod (item-prod item))
(rhs (prod-rhs prod))
(lhs (prod-lhs prod)))
(map (lambda (state)
(make-trans-key state lhs))
(run-lr0-backward a
rhs
(item-dot-pos item)
goal-state
num-states))))
items)))))))
;; compute-lookback: lr0-automaton * grammar -> (kernel * proc -> trans-key list)
(define (compute-lookback a g)
(let ((num-states (send a get-num-states)))
(lambda (state prod)
(map (lambda (k) (make-trans-key k (prod-lhs prod)))
(run-lr0-backward a (prod-rhs prod) (vector-length (prod-rhs prod)) state num-states)))))
;; compute-follow: LR0-automaton * grammar -> (trans-key -> term set)
;; output term set is represented in bit-vector form
(define (compute-follow a g includes)
(let ((read (compute-read a g)))
(digraph-tk->terml (send a get-mapped-non-term-keys)
includes
read
(send a get-num-states))))
;; compute-LA: LR0-automaton * grammar -> kernel * prod -> term set
;; output term set is represented in bit-vector form
(define (compute-LA a g)
(let* ((includes (compute-includes a g))
(lookback (compute-lookback a g))
(follow (compute-follow a g includes)))
(lambda (k p)
(let* ((l (lookback k p))
(f (map follow l)))
(apply bitwise-ior (cons 0 f))))))
(define (print-DR dr a g)
(print-input-st-sym dr "DR" a g print-output-terms))
(define (print-Read Read a g)
(print-input-st-sym Read "Read" a g print-output-terms))
(define (print-includes i a g)
(print-input-st-sym i "includes" a g print-output-st-nt))
(define (print-lookback l a g)
(print-input-st-prod l "lookback" a g print-output-st-nt))
(define (print-follow f a g)
(print-input-st-sym f "follow" a g print-output-terms))
(define (print-LA l a g)
(print-input-st-prod l "LA" a g print-output-terms))
(define (print-input-st-sym f name a g print-output)
(printf "~a:\n" name)
(send a for-each-state
(lambda (state)
(for-each
(lambda (non-term)
(let ((res (f (make-trans-key state non-term))))
(if (not (null? res))
(printf "~a(~a, ~a) = ~a\n"
name
state
(gram-sym-symbol non-term)
(print-output res)))))
(send g get-non-terms))))
(newline))
(define (print-input-st-prod f name a g print-output)
(printf "~a:\n" name)
(send a for-each-state
(lambda (state)
(for-each
(lambda (non-term)
(for-each
(lambda (prod)
(let ((res (f state prod)))
(if (not (null? res))
(printf "~a(~a, ~a) = ~a\n"
name
(kernel-index state)
(prod-index prod)
(print-output res)))))
(send g get-prods-for-non-term non-term)))
(send g get-non-terms)))))
(define (print-output-terms r)
(map
(lambda (p)
(gram-sym-symbol p))
r))
(define (print-output-st-nt r)
(map
(lambda (p)
(list
(kernel-index (trans-key-st p))
(gram-sym-symbol (trans-key-gs p))))
r))
;; init-tk-map : int -> (vectorof hashtable?)
(define (init-tk-map n)
(let ((v (make-vector n #f)))
(let loop ((i (sub1 (vector-length v))))
(when (>= i 0)
(vector-set! v i (make-hash-table))
(loop (sub1 i))))
v))
;; lookup-tk-map : (vectorof (symbol? int hashtable)) -> trans-key? -> int
(define (lookup-tk-map map)
(lambda (tk)
(let ((st (trans-key-st tk))
(gs (trans-key-gs tk)))
(hash-table-get (vector-ref map (kernel-index st))
(gram-sym-symbol gs)
(lambda () 0)))))
;; add-tk-map : (vectorof (symbol? int hashtable)) -> trans-key int ->
(define (add-tk-map map)
(lambda (tk v)
(let ((st (trans-key-st tk))
(gs (trans-key-gs tk)))
(hash-table-put! (vector-ref map (kernel-index st))
(gram-sym-symbol gs)
v))))
;; digraph-tk->terml:
;; (trans-key list) * (trans-key -> trans-key list) * (trans-key -> term list) * int * int * int
;; -> (trans-key -> term list)
;; DeRemer and Pennello 1982
;; Computes (f x) = (f- x) union Union{(f y) | y in (edges x)}
;; A specialization of digraph in the file graph.rkt
(define (digraph-tk->terml nodes edges f- num-states)
(letrec [
;; Will map elements of trans-key to term sets represented as bit vectors
(results (init-tk-map num-states))
;; Maps elements of trans-keys to integers.
(N (init-tk-map num-states))
(get-N (lookup-tk-map N))
(set-N (add-tk-map N))
(get-f (lookup-tk-map results))
(set-f (add-tk-map results))
(stack null)
(push (lambda (x)
(set! stack (cons x stack))))
(pop (lambda ()
(begin0
(car stack)
(set! stack (cdr stack)))))
(depth (lambda () (length stack)))
;; traverse: 'a ->
(traverse
(lambda (x)
(push x)
(let ((d (depth)))
(set-N x d)
(set-f x (f- x))
(for-each (lambda (y)
(when (= 0 (get-N y))
(traverse y))
(set-f x (bitwise-ior (get-f x) (get-f y)))
(set-N x (min (get-N x) (get-N y))))
(edges x))
(when (= d (get-N x))
(let loop ((p (pop)))
(set-N p +inf.0)
(set-f p (get-f x))
(unless (equal? x p)
(loop (pop))))))))]
(for-each (lambda (x)
(when (= 0 (get-N x))
(traverse x)))
nodes)
get-f))
)

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(module lr0 mzscheme
;; Handle the LR0 automaton
(require "grammar.rkt"
"graph.rkt"
mzlib/list
mzlib/class)
(provide build-lr0-automaton lr0%
(struct trans-key (st gs)) trans-key-list-remove-dups
kernel-items kernel-index)
;; kernel = (make-kernel (LR1-item list) index)
;; the list must be kept sorted according to item<? so that equal? can
;; be used to compare kernels
;; Each kernel is assigned a unique index, 0 <= index < number of states
;; trans-key = (make-trans-key kernel gram-sym)
(define-struct kernel (items index) (make-inspector))
(define-struct trans-key (st gs) (make-inspector))
(define (trans-key<? a b)
(let ((kia (kernel-index (trans-key-st a)))
(kib (kernel-index (trans-key-st b))))
(or (< kia kib)
(and (= kia kib)
(< (non-term-index (trans-key-gs a))
(non-term-index (trans-key-gs b)))))))
(define (trans-key-list-remove-dups tkl)
(let loop ((sorted (sort tkl trans-key<?)))
(cond
((null? sorted) null)
((null? (cdr sorted)) sorted)
(else
(if (and (= (non-term-index (trans-key-gs (car sorted)))
(non-term-index (trans-key-gs (cadr sorted))))
(= (kernel-index (trans-key-st (car sorted)))
(kernel-index (trans-key-st (cadr sorted)))))
(loop (cdr sorted))
(cons (car sorted) (loop (cdr sorted))))))))
;; build-transition-table : int (listof (cons/c trans-key X) ->
;; (vectorof (symbol X hashtable))
(define (build-transition-table num-states assoc)
(let ((transitions (make-vector num-states #f)))
(let loop ((i (sub1 (vector-length transitions))))
(when (>= i 0)
(vector-set! transitions i (make-hash-table))
(loop (sub1 i))))
(for-each
(lambda (trans-key/kernel)
(let ((tk (car trans-key/kernel)))
(hash-table-put! (vector-ref transitions (kernel-index (trans-key-st tk)))
(gram-sym-symbol (trans-key-gs tk))
(cdr trans-key/kernel))))
assoc)
transitions))
;; reverse-assoc : (listof (cons/c trans-key? kernel?)) ->
;; (listof (cons/c trans-key? (listof kernel?)))
(define (reverse-assoc assoc)
(let ((reverse-hash (make-hash-table 'equal))
(hash-table-add!
(lambda (ht k v)
(hash-table-put! ht k (cons v (hash-table-get ht k (lambda () null)))))))
(for-each
(lambda (trans-key/kernel)
(let ((tk (car trans-key/kernel)))
(hash-table-add! reverse-hash
(make-trans-key (cdr trans-key/kernel)
(trans-key-gs tk))
(trans-key-st tk))))
assoc)
(hash-table-map reverse-hash cons)))
;; kernel-list-remove-duplicates
;; LR0-automaton = object of class lr0%
(define lr0%
(class object%
(super-instantiate ())
;; term-assoc : (listof (cons/c trans-key? kernel?))
;; non-term-assoc : (listof (cons/c trans-key? kernel?))
;; states : (vectorof kernel?)
;; epsilons : ???
(init-field term-assoc non-term-assoc states epsilons)
(define transitions (build-transition-table (vector-length states)
(append term-assoc non-term-assoc)))
(define reverse-term-assoc (reverse-assoc term-assoc))
(define reverse-non-term-assoc (reverse-assoc non-term-assoc))
(define reverse-transitions
(build-transition-table (vector-length states)
(append reverse-term-assoc reverse-non-term-assoc)))
(define mapped-non-terms (map car non-term-assoc))
(define/public (get-mapped-non-term-keys)
mapped-non-terms)
(define/public (get-num-states)
(vector-length states))
(define/public (get-epsilon-trans)
epsilons)
(define/public (get-transitions)
(append term-assoc non-term-assoc))
;; for-each-state : (state ->) ->
;; Iteration over the states in an automaton
(define/public (for-each-state f)
(let ((num-states (vector-length states)))
(let loop ((i 0))
(if (< i num-states)
(begin
(f (vector-ref states i))
(loop (add1 i)))))))
;; run-automaton: kernel? gram-sym? -> (union kernel #f)
;; returns the state reached from state k on input s, or #f when k
;; has no transition on s
(define/public (run-automaton k s)
(hash-table-get (vector-ref transitions (kernel-index k))
(gram-sym-symbol s)
(lambda () #f)))
;; run-automaton-back : (listof kernel?) gram-sym? -> (listof kernel)
;; returns the list of states that can reach k by transitioning on s.
(define/public (run-automaton-back k s)
(apply append
(map
(lambda (k)
(hash-table-get (vector-ref reverse-transitions (kernel-index k))
(gram-sym-symbol s)
(lambda () null)))
k)))))
(define (union comp<?)
(letrec ((union
(lambda (l1 l2)
(cond
((null? l1) l2)
((null? l2) l1)
(else (let ((c1 (car l1))
(c2 (car l2)))
(cond
((comp<? c1 c2)
(cons c1 (union (cdr l1) l2)))
((comp<? c2 c1)
(cons c2 (union l1 (cdr l2))))
(else (union (cdr l1) l2)))))))))
union))
;; The kernels in the automaton are represented cannonically.
;; That is (equal? a b) <=> (eq? a b)
(define (kernel->string k)
(apply string-append
`("{" ,@(map (lambda (i) (string-append (item->string i) ", "))
(kernel-items k))
"}")))
;; build-LR0-automaton: grammar -> LR0-automaton
;; Constructs the kernels of the sets of LR(0) items of g
(define (build-lr0-automaton grammar)
; (printf "LR(0) automaton:\n")
(letrec (
(epsilons (make-hash-table 'equal))
(grammar-symbols (append (send grammar get-non-terms)
(send grammar get-terms)))
;; first-non-term: non-term -> non-term list
;; given a non-terminal symbol C, return those non-terminal
;; symbols A s.t. C -> An for some string of terminals and
;; non-terminals n where -> means a rightmost derivation in many
;; steps. Assumes that each non-term can be reduced to a string
;; of terms.
(first-non-term
(digraph (send grammar get-non-terms)
(lambda (nt)
(filter non-term?
(map (lambda (prod)
(sym-at-dot (make-item prod 0)))
(send grammar get-prods-for-non-term nt))))
(lambda (nt) (list nt))
(union non-term<?)
(lambda () null)))
;; closure: LR1-item list -> LR1-item list
;; Creates a set of items containing i s.t. if A -> n.Xm is in it,
;; X -> .o is in it too.
(LR0-closure
(lambda (i)
(cond
((null? i) null)
(else
(let ((next-gsym (sym-at-dot (car i))))
(cond
((non-term? next-gsym)
(cons (car i)
(append
(apply append
(map (lambda (non-term)
(map (lambda (x)
(make-item x 0))
(send grammar
get-prods-for-non-term
non-term)))
(first-non-term next-gsym)))
(LR0-closure (cdr i)))))
(else
(cons (car i) (LR0-closure (cdr i))))))))))
;; maps trans-keys to kernels
(automaton-term null)
(automaton-non-term null)
;; keeps the kernels we have seen, so we can have a unique
;; list for each kernel
(kernels (make-hash-table 'equal))
(counter 0)
;; goto: LR1-item list -> LR1-item list list
;; creates new kernels by moving the dot in each item in the
;; LR0-closure of kernel to the right, and grouping them by
;; the term/non-term moved over. Returns the kernels not
;; yet seen, and places the trans-keys into automaton
(goto
(lambda (kernel)
(let (
;; maps a gram-syms to a list of items
(table (make-hash-table))
;; add-item!:
;; (symbol (listof item) hashtable) item? ->
;; adds i into the table grouped with the grammar
;; symbol following its dot
(add-item!
(lambda (table i)
(let ((gs (sym-at-dot i)))
(cond
(gs
(let ((already
(hash-table-get table
(gram-sym-symbol gs)
(lambda () null))))
(unless (member i already)
(hash-table-put! table
(gram-sym-symbol gs)
(cons i already)))))
((= 0 (vector-length (prod-rhs (item-prod i))))
(let ((current (hash-table-get epsilons
kernel
(lambda () null))))
(hash-table-put! epsilons
kernel
(cons i current)))))))))
;; Group the items of the LR0 closure of the kernel
;; by the character after the dot
(for-each (lambda (item)
(add-item! table item))
(LR0-closure (kernel-items kernel)))
;; each group is a new kernel, with the dot advanced.
;; sorts the items in a kernel so kernels can be compared
;; with equal? for using the table kernels to make sure
;; only one representitive of each kernel is created
(filter
(lambda (x) x)
(map
(lambda (i)
(let* ((gs (car i))
(items (cadr i))
(new #f)
(new-kernel (sort
(filter (lambda (x) x)
(map move-dot-right items))
item<?))
(unique-kernel (hash-table-get
kernels
new-kernel
(lambda ()
(let ((k (make-kernel
new-kernel
counter)))
(set! new #t)
(set! counter (add1 counter))
(hash-table-put! kernels
new-kernel
k)
k)))))
(cond
((term? gs)
(set! automaton-term (cons (cons (make-trans-key kernel gs)
unique-kernel)
automaton-term)))
(else
(set! automaton-non-term (cons (cons (make-trans-key kernel gs)
unique-kernel)
automaton-non-term))))
#;(printf "~a -> ~a on ~a\n"
(kernel->string kernel)
(kernel->string unique-kernel)
(gram-sym-symbol gs))
(if new
unique-kernel
#f)))
(let loop ((gsyms grammar-symbols))
(cond
((null? gsyms) null)
(else
(let ((items (hash-table-get table
(gram-sym-symbol (car gsyms))
(lambda () null))))
(cond
((null? items) (loop (cdr gsyms)))
(else
(cons (list (car gsyms) items)
(loop (cdr gsyms))))))))))))))
(starts
(map (lambda (init-prod) (list (make-item init-prod 0)))
(send grammar get-init-prods)))
(startk
(map (lambda (start)
(let ((k (make-kernel start counter)))
(hash-table-put! kernels start k)
(set! counter (add1 counter))
k))
starts))
(new-kernels (make-queue)))
(let loop ((old-kernels startk)
(seen-kernels null))
(cond
((and (empty-queue? new-kernels) (null? old-kernels))
(make-object lr0%
automaton-term
automaton-non-term
(list->vector (reverse seen-kernels))
epsilons))
((null? old-kernels)
(loop (deq! new-kernels) seen-kernels))
(else
(enq! new-kernels (goto (car old-kernels)))
(loop (cdr old-kernels) (cons (car old-kernels) seen-kernels)))))))
(define-struct q (f l) (make-inspector))
(define (empty-queue? q)
(null? (q-f q)))
(define (make-queue)
(make-q null null))
(define (enq! q i)
(if (empty-queue? q)
(let ((i (mcons i null)))
(set-q-l! q i)
(set-q-f! q i))
(begin
(set-mcdr! (q-l q) (mcons i null))
(set-q-l! q (mcdr (q-l q))))))
(define (deq! q)
(begin0
(mcar (q-f q))
(set-q-f! q (mcdr (q-f q)))))
)

54
br-parser-tools/br-parser-tools-lib/br-parser-tools/private-yacc/parser-actions.rkt
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(module parser-actions mzscheme
(require "grammar.rkt")
(provide (all-defined-except make-reduce make-reduce*)
(rename make-reduce* make-reduce))
;; An action is
;; - (make-shift int)
;; - (make-reduce prod runtime-action)
;; - (make-accept)
;; - (make-goto int)
;; - (no-action)
;; A reduce contains a runtime-reduce so that sharing of the reduces can
;; be easily transferred to sharing of runtime-reduces.
(define-struct action () (make-inspector))
(define-struct (shift action) (state) (make-inspector))
(define-struct (reduce action) (prod runtime-reduce) (make-inspector))
(define-struct (accept action) () (make-inspector))
(define-struct (goto action) (state) (make-inspector))
(define-struct (no-action action) () (make-inspector))
(define (make-reduce* p)
(make-reduce p
(vector (prod-index p)
(gram-sym-symbol (prod-lhs p))
(vector-length (prod-rhs p)))))
;; A runtime-action is
;; non-negative-int (shift)
;; (vector int symbol int) (reduce)
;; 'accept (accept)
;; negative-int (goto)
;; #f (no-action)
(define (action->runtime-action a)
(cond
((shift? a) (shift-state a))
((reduce? a) (reduce-runtime-reduce a))
((accept? a) 'accept)
((goto? a) (- (+ (goto-state a) 1)))
((no-action? a) #f)))
(define (runtime-shift? x) (and (integer? x) (>= x 0)))
(define runtime-reduce? vector?)
(define (runtime-accept? x) (eq? x 'accept))
(define (runtime-goto? x) (and (integer? x) (< x 0)))
(define runtime-shift-state values)
(define (runtime-reduce-prod-num x) (vector-ref x 0))
(define (runtime-reduce-lhs x) (vector-ref x 1))
(define (runtime-reduce-rhs-length x) (vector-ref x 2))
(define (runtime-goto-state x) (- (+ x 1)))
)

113
br-parser-tools/br-parser-tools-lib/br-parser-tools/private-yacc/parser-builder.rkt
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(module parser-builder mzscheme
(require "input-file-parser.rkt"
"grammar.rkt"
"table.rkt"
mzlib/class
racket/contract)
(require-for-template mzscheme)
(provide/contract
(build-parser (-> string? any/c any/c
(listof identifier?)
(listof identifier?)
(listof identifier?)
(or/c syntax? #f)
syntax?
(values any/c any/c any/c any/c))))
;; fix-check-syntax : (listof identifier?) (listof identifier?) (listof identifier?)
;; (union syntax? false/c) syntax?) -> syntax?
(define (fix-check-syntax input-terms start ends assocs prods)
(let* ((term-binders (get-term-list input-terms))
(get-term-binder
(let ((t (make-hash-table)))
(for-each
(lambda (term)
(hash-table-put! t (syntax-e term) term))
term-binders)
(lambda (x)
(let ((r (hash-table-get t (syntax-e x) (lambda () #f))))
(if r
(syntax-local-introduce (datum->syntax-object r (syntax-e x) x x))
x)))))
(rhs-list
(syntax-case prods ()
(((_ rhs ...) ...)
(syntax->list (syntax (rhs ... ...)))))))
(with-syntax (((tmp ...) (map syntax-local-introduce term-binders))
((term-group ...)
(map (lambda (tg)
(syntax-property
(datum->syntax-object tg #f)
'disappeared-use
tg))
input-terms))
((end ...)
(map get-term-binder ends))
((start ...)
(map get-term-binder start))
((bind ...)
(syntax-case prods ()
(((bind _ ...) ...)
(syntax->list (syntax (bind ...))))))
(((bound ...) ...)
(map
(lambda (rhs)
(syntax-case rhs ()
(((bound ...) (_ pbound) __)
(map get-term-binder
(cons (syntax pbound)
(syntax->list (syntax (bound ...))))))
(((bound ...) _)
(map get-term-binder
(syntax->list (syntax (bound ...)))))))
rhs-list))
((prec ...)
(if assocs
(map get-term-binder
(syntax-case assocs ()
(((__ term ...) ...)
(syntax->list (syntax (term ... ...))))))
null)))
#`(when #f
(let ((bind void) ... (tmp void) ...)
(void bound ... ... term-group ... start ... end ... prec ...))))))
(require mzlib/list "parser-actions.rkt")
(define (build-parser filename src-pos suppress input-terms start end assocs prods)
(let* ((grammar (parse-input input-terms start end assocs prods src-pos))
(table (build-table grammar filename suppress))
(all-tokens (make-hash-table))
(actions-code
`(vector ,@(map prod-action (send grammar get-prods)))))
(for-each (lambda (term)
(hash-table-put! all-tokens (gram-sym-symbol term) #t))
(send grammar get-terms))
#;(let ((num-states (vector-length table))
(num-gram-syms (+ (send grammar get-num-terms)
(send grammar get-num-non-terms)))
(num-ht-entries (apply + (map length (vector->list table))))
(num-reduces
(let ((ht (make-hash-table)))
(for-each
(lambda (x)
(when (reduce? x)
(hash-table-put! ht x #t)))
(map cdr (apply append (vector->list table))))
(length (hash-table-map ht void)))))
(printf "~a states, ~a grammar symbols, ~a hash-table entries, ~a reduces\n"
num-states num-gram-syms num-ht-entries num-reduces)
(printf "~a -- ~aKB, previously ~aKB\n"
(/ (+ 2 num-states
(* 4 num-states) (* 2 1.5 num-ht-entries)
(* 5 num-reduces)) 256.0)
(/ (+ 2 num-states
(* 4 num-states) (* 2 2.3 num-ht-entries)
(* 5 num-reduces)) 256.0)
(/ (+ 2 (* num-states num-gram-syms) (* 5 num-reduces)) 256.0)))
(values table
all-tokens
actions-code
(fix-check-syntax input-terms start end assocs prods))))
)

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br-parser-tools/br-parser-tools-lib/br-parser-tools/private-yacc/table.rkt
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#lang scheme/base
;; Routine to build the LALR table
(require "grammar.rkt"
"lr0.rkt"
"lalr.rkt"
"parser-actions.rkt"
racket/contract
mzlib/list
mzlib/class)
(define (is-a-grammar%? x) (is-a? x grammar%))
(provide/contract
(build-table (-> is-a-grammar%? string? any/c
(vectorof (listof (cons/c (or/c term? non-term?) action?))))))
;; A parse-table is (vectorof (listof (cons/c gram-sym? action)))
;; A grouped-parse-table is (vectorof (listof (cons/c gram-sym? (listof action))))
;; make-parse-table : int -> parse-table
(define (make-parse-table num-states)
(make-vector num-states null))
;; table-add!: parse-table nat symbol action ->
(define (table-add! table state-index symbol val)
(vector-set! table state-index (cons (cons symbol val)
(vector-ref table state-index))))
;; group-table : parse-table -> grouped-parse-table
(define (group-table table)
(list->vector
(map
(lambda (state-entry)
(let ((ht (make-hash)))
(for-each
(lambda (gs/actions)
(let ((group (hash-ref ht (car gs/actions) (lambda () null))))
(unless (member (cdr gs/actions) group)
(hash-set! ht (car gs/actions) (cons (cdr gs/actions) group)))))
state-entry)
(hash-map ht cons)))
(vector->list table))))
;; table-map : (vectorof (listof (cons/c gram-sym? X))) (gram-sym? X -> Y) ->
;; (vectorof (listof (cons/c gram-sym? Y)))
(define (table-map f table)
(list->vector
(map
(lambda (state-entry)
(map
(lambda (gs/X)
(cons (car gs/X) (f (car gs/X) (cdr gs/X))))
state-entry))
(vector->list table))))
(define (bit-vector-for-each f bv)
(letrec ((for-each
(lambda (bv number)
(cond
((= 0 bv) (void))
((= 1 (bitwise-and 1 bv))
(f number)
(for-each (arithmetic-shift bv -1) (add1 number)))
(else (for-each (arithmetic-shift bv -1) (add1 number)))))))
(for-each bv 0)))
;; print-entry: symbol action output-port ->
;; prints the action a for lookahead sym to the given port
(define (print-entry sym a port)
(let ((s "\t~a\t\t\t\t\t~a\t~a\n"))
(cond
((shift? a)
(fprintf port s sym "shift" (shift-state a)))
((reduce? a)
(fprintf port s sym "reduce" (prod-index (reduce-prod a))))
((accept? a)
(fprintf port s sym "accept" ""))
((goto? a)
(fprintf port s sym "goto" (goto-state a))))))
;; count: ('a -> bool) * 'a list -> num
;; counts the number of elements in list that satisfy pred
(define (count pred list)
(cond
((null? list) 0)
((pred (car list)) (+ 1 (count pred (cdr list))))
(else (count pred (cdr list)))))
;; display-parser: LR0-automaton grouped-parse-table (listof prod?) output-port ->
;; Prints out the parser given by table.
(define (display-parser a grouped-table prods port)
(let* ((SR-conflicts 0)
(RR-conflicts 0))
(for-each
(lambda (prod)
(fprintf port
"~a\t~a\t=\t~a\n"
(prod-index prod)
(gram-sym-symbol (prod-lhs prod))
(map gram-sym-symbol (vector->list (prod-rhs prod)))))
prods)
(send a for-each-state
(lambda (state)
(fprintf port "State ~a\n" (kernel-index state))
(for-each (lambda (item)
(fprintf port "\t~a\n" (item->string item)))
(kernel-items state))
(newline port)
(for-each
(lambda (gs/action)
(let ((sym (gram-sym-symbol (car gs/action)))
(act (cdr gs/action)))
(cond
((null? act) (void))
((null? (cdr act))
(print-entry sym (car act) port))
(else
(fprintf port "begin conflict:\n")
(when (> (count reduce? act) 1)
(set! RR-conflicts (add1 RR-conflicts)))
(when (> (count shift? act) 0)
(set! SR-conflicts (add1 SR-conflicts)))
(map (lambda (x) (print-entry sym x port)) act)
(fprintf port "end conflict\n")))))
(vector-ref grouped-table (kernel-index state)))
(newline port)))
(when (> SR-conflicts 0)
(fprintf port "~a shift/reduce conflict~a\n"
SR-conflicts
(if (= SR-conflicts 1) "" "s")))
(when (> RR-conflicts 0)
(fprintf port "~a reduce/reduce conflict~a\n"
RR-conflicts
(if (= RR-conflicts 1) "" "s")))))
;; resolve-conflict : (listof action?) -> action? bool bool
(define (resolve-conflict actions)
(cond
((null? actions) (values (make-no-action) #f #f))
((null? (cdr actions))
(values (car actions) #f #f))
(else
(let ((SR-conflict? (> (count shift? actions) 0))
(RR-conflict? (> (count reduce? actions) 1)))
(let loop ((current-guess #f)
(rest actions))
(cond
((null? rest) (values current-guess SR-conflict? RR-conflict?))
((shift? (car rest)) (values (car rest) SR-conflict? RR-conflict?))
((not current-guess)
(loop (car rest) (cdr rest)))
((and (reduce? (car rest))
(< (prod-index (reduce-prod (car rest)))
(prod-index (reduce-prod current-guess))))
(loop (car rest) (cdr rest)))
((accept? (car rest))
(eprintf "accept/reduce or accept/shift conflicts. Check the grammar for useless cycles of productions\n")
(loop current-guess (cdr rest)))
(else (loop current-guess (cdr rest)))))))))
;; resolve-conflicts : grouped-parse-table bool -> parse-table
(define (resolve-conflicts grouped-table suppress)
(let* ((SR-conflicts 0)
(RR-conflicts 0)
(table (table-map
(lambda (gs actions)
(let-values (((action SR? RR?)
(resolve-conflict actions)))
(when SR?
(set! SR-conflicts (add1 SR-conflicts)))
(when RR?
(set! RR-conflicts (add1 RR-conflicts)))
action))
grouped-table)))
(unless suppress
(when (> SR-conflicts 0)
(eprintf "~a shift/reduce conflict~a\n"
SR-conflicts
(if (= SR-conflicts 1) "" "s")))
(when (> RR-conflicts 0)
(eprintf "~a reduce/reduce conflict~a\n"
RR-conflicts
(if (= RR-conflicts 1) "" "s"))))
table))
;; resolve-sr-conflict : (listof action) (union int #f) -> (listof action)
;; Resolves a single shift-reduce conflict, if precedences are in place.
(define (resolve-sr-conflict/prec actions shift-prec)
(let* ((shift (if (shift? (car actions))
(car actions)
(cadr actions)))
(reduce (if (shift? (car actions))
(cadr actions)
(car actions)))
(reduce-prec (prod-prec (reduce-prod reduce))))
(cond
((and shift-prec reduce-prec)
(cond
((< (prec-num shift-prec) (prec-num reduce-prec))
(list reduce))
((> (prec-num shift-prec) (prec-num reduce-prec))
(list shift))
((eq? 'left (prec-assoc shift-prec))
(list reduce))
((eq? 'right (prec-assoc shift-prec))
(list shift))
(else null)))
(else actions))))
;; resolve-prec-conflicts : parse-table -> grouped-parse-table
(define (resolve-prec-conflicts table)
(table-map
(lambda (gs actions)
(cond
((and (term? gs)
(= 2 (length actions))
(or (shift? (car actions))
(shift? (cadr actions))))
(resolve-sr-conflict/prec actions (term-prec gs)))
(else actions)))
(group-table table)))
;; build-table: grammar string bool -> parse-table
(define (build-table g file suppress)
(let* ((a (build-lr0-automaton g))
(term-vector (list->vector (send g get-terms)))
(end-terms (send g get-end-terms))
(table (make-parse-table (send a get-num-states)))
(get-lookahead (compute-LA a g))
(reduce-cache (make-hash)))
(for-each
(lambda (trans-key/state)
(let ((from-state-index (kernel-index (trans-key-st (car trans-key/state))))
(gs (trans-key-gs (car trans-key/state)))
(to-state (cdr trans-key/state)))
(table-add! table from-state-index gs
(cond
((non-term? gs)
(make-goto (kernel-index to-state)))
((member gs end-terms)
(make-accept))
(else
(make-shift
(kernel-index to-state)))))))
(send a get-transitions))
(send a for-each-state
(lambda (state)
(for-each
(lambda (item)
(let ((item-prod (item-prod item)))
(bit-vector-for-each
(lambda (term-index)
(unless (start-item? item)
(let ((r (hash-ref reduce-cache item-prod
(lambda ()
(let ((r (make-reduce item-prod)))
(hash-set! reduce-cache item-prod r)
r)))))
(table-add! table
(kernel-index state)
(vector-ref term-vector term-index)
r))))
(get-lookahead state item-prod))))
(append (hash-ref (send a get-epsilon-trans) state (lambda () null))
(filter (lambda (item)
(not (move-dot-right item)))
(kernel-items state))))))
(let ((grouped-table (resolve-prec-conflicts table)))
(unless (string=? file "")
(with-handlers [(exn:fail:filesystem?
(lambda (e)
(eprintf
"Cannot write debug output to file \"~a\": ~a\n"
file
(exn-message e))))]
(call-with-output-file file
(lambda (port)
(display-parser a grouped-table (send g get-prods) port))
#:exists 'truncate)))
(resolve-conflicts grouped-table suppress))))

118
br-parser-tools/br-parser-tools-lib/br-parser-tools/private-yacc/yacc-helper.rkt
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(module yacc-helper mzscheme
(require mzlib/list
"../private-lex/token-syntax.rkt")
;; General helper routines
(provide duplicate-list? remove-duplicates overlap? vector-andmap display-yacc)
(define (vector-andmap f v)
(let loop ((i 0))
(cond
((= i (vector-length v)) #t)
(else (if (f (vector-ref v i))
(loop (add1 i))
#f)))))
;; duplicate-list?: symbol list -> #f | symbol
;; returns a symbol that exists twice in l, or false if no such symbol
;; exists
(define (duplicate-list? l)
(letrec ((t (make-hash-table))
(dl? (lambda (l)
(cond
((null? l) #f)
((hash-table-get t (car l) (lambda () #f)) =>
(lambda (x) x))
(else
(hash-table-put! t (car l) (car l))
(dl? (cdr l)))))))
(dl? l)))
;; remove-duplicates: syntax-object list -> syntax-object list
;; removes the duplicates from the lists
(define (remove-duplicates sl)
(let ((t (make-hash-table)))
(letrec ((x
(lambda (sl)
(cond
((null? sl) sl)
((hash-table-get t (syntax-object->datum (car sl)) (lambda () #f))
(x (cdr sl)))
(else
(hash-table-put! t (syntax-object->datum (car sl)) #t)
(cons (car sl) (x (cdr sl))))))))
(x sl))))
;; overlap?: symbol list * symbol list -> #f | symbol
;; Returns an symbol in l1 intersect l2, or #f is no such symbol exists
(define (overlap? l1 l2)
(let/ec ret
(let ((t (make-hash-table)))
(for-each (lambda (s1)
(hash-table-put! t s1 s1))
l1)
(for-each (lambda (s2)
(cond
((hash-table-get t s2 (lambda () #f)) =>
(lambda (o) (ret o)))))
l2)
#f)))
(define (display-yacc grammar tokens start precs port)
(let-syntax ((p (syntax-rules ()
((_ args ...) (fprintf port args ...)))))
(let* ((tokens (map syntax-local-value tokens))
(eterms (filter e-terminals-def? tokens))
(terms (filter terminals-def? tokens))
(term-table (make-hash-table))
(display-rhs
(lambda (rhs)
(for-each (lambda (sym) (p "~a " (hash-table-get term-table sym (lambda () sym))))
(car rhs))
(if (= 3 (length rhs))
(p "%prec ~a" (cadadr rhs)))
(p "\n"))))
(for-each
(lambda (t)
(for-each
(lambda (t)
(hash-table-put! term-table t (format "'~a'" t)))
(syntax-object->datum (e-terminals-def-t t))))
eterms)
(for-each
(lambda (t)
(for-each
(lambda (t)
(p "%token ~a\n" t)
(hash-table-put! term-table t (format "~a" t)))
(syntax-object->datum (terminals-def-t t))))
terms)
(if precs
(for-each (lambda (prec)
(p "%~a " (car prec))
(for-each (lambda (tok)
(p " ~a" (hash-table-get term-table tok)))
(cdr prec))
(p "\n"))
precs))
(p "%start ~a\n" start)
(p "%%\n")
(for-each (lambda (prod)
(let ((nt (car prod)))
(p "~a: " nt)
(display-rhs (cadr prod))
(for-each (lambda (rhs)
(p "| ")
(display-rhs rhs))
(cddr prod))
(p ";\n")))
grammar)
(p "%%\n"))))
)

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br-parser-tools/br-parser-tools-lib/br-parser-tools/yacc-to-scheme.rkt
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(module yacc-to-scheme mzscheme
(require br-parser-tools/lex
(prefix : br-parser-tools/lex-sre)
br-parser-tools/yacc
syntax/readerr
mzlib/list)
(provide trans)
(define match-double-string
(lexer
((:+ (:~ #\" #\\)) (append (string->list lexeme)
(match-double-string input-port)))
((:: #\\ any-char) (cons (string-ref lexeme 1) (match-double-string input-port)))
(#\" null)))
(define match-single-string
(lexer
((:+ (:~ #\' #\\)) (append (string->list lexeme)
(match-single-string input-port)))
((:: #\\ any-char) (cons (string-ref lexeme 1) (match-single-string input-port)))
(#\' null)))
(define-lex-abbrevs
(letter (:or (:/ "a" "z") (:/ "A" "Z")))
(digit (:/ "0" "9"))
(initial (:or letter (char-set "!$%&*/<=>?^_~@")))
(subsequent (:or initial digit (char-set "+-.@")))
(comment (:: "/*" (complement (:: any-string "*/" any-string)) "*/")))
(define-empty-tokens x
(EOF PIPE |:| SEMI |%%| %prec))
(define-tokens y
(SYM STRING))
(define get-token-grammar
(lexer-src-pos
("%%" '|%%|)
(":" (string->symbol lexeme))
("%prec" (string->symbol lexeme))
(#\| 'PIPE)
((:+ (:or #\newline #\tab " " comment (:: "{" (:* (:~ "}")) "}")))
(return-without-pos (get-token-grammar input-port)))
(#\; 'SEMI)
(#\' (token-STRING (string->symbol (list->string (match-single-string input-port)))))
(#\" (token-STRING (string->symbol (list->string (match-double-string input-port)))))
((:: initial (:* subsequent)) (token-SYM (string->symbol lexeme)))))
(define (parse-grammar enter-term enter-empty-term enter-non-term)
(parser
(tokens x y)
(src-pos)
(error (lambda (tok-ok tok-name tok-value start-pos end-pos)
(raise-read-error
(format "Error Parsing YACC grammar at token: ~a with value: ~a" tok-name tok-value)
(file-path)
(position-line start-pos)
(position-col start-pos)
(position-offset start-pos)
(- (position-offset end-pos) (position-offset start-pos)))))
(end |%%|)
(start gram)
(grammar
(gram
((production) (list $1))
((production gram) (cons $1 $2)))
(production
((SYM |:| prods SEMI)
(begin
(enter-non-term $1)
(cons $1 $3))))
(prods
((rhs) (list `(,$1 #f)))
((rhs prec) (list `(,$1 ,$2 #f)))
((rhs PIPE prods) (cons `(,$1 #f) $3))
((rhs prec PIPE prods) (cons `(,$1 ,$2 #f) $4)))
(prec
((%prec SYM)
(begin
(enter-term $2)
(list 'prec $2)))
((%prec STRING)
(begin
(enter-empty-term $2)
(list 'prec $2))))
(rhs
(() null)
((SYM rhs)
(begin
(enter-term $1)
(cons $1 $2)))
((STRING rhs)
(begin
(enter-empty-term $1)
(cons $1 $2)))))))
(define (symbol<? a b)
(string<? (symbol->string a) (symbol->string b)))
(define (trans filename)
(let* ((i (open-input-file filename))
(terms (make-hash-table))
(eterms (make-hash-table))
(nterms (make-hash-table))
(enter-term
(lambda (s)
(if (not (hash-table-get nterms s (lambda () #f)))
(hash-table-put! terms s #t))))
(enter-empty-term
(lambda (s)
(if (not (hash-table-get nterms s (lambda () #f)))
(hash-table-put! eterms s #t))))
(enter-non-term
(lambda (s)
(hash-table-remove! terms s)
(hash-table-remove! eterms s)
(hash-table-put! nterms s #t))))
(port-count-lines! i)
(file-path filename)
(regexp-match "%%" i)
(begin0
(let ((gram ((parse-grammar enter-term enter-empty-term enter-non-term)
(lambda ()
(let ((t (get-token-grammar i)))
t)))))
`(begin
(define-tokens t ,(sort (hash-table-map terms (lambda (k v) k)) symbol<?))
(define-empty-tokens et ,(sort (hash-table-map eterms (lambda (k v) k)) symbol<?))
(parser
(start ___)
(end ___)
(error ___)
(tokens t et)
(grammar ,@gram))))
(close-input-port i)))))

412
br-parser-tools/br-parser-tools-lib/br-parser-tools/yacc.rkt
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#lang scheme/base
(require (for-syntax scheme/base
"private-yacc/parser-builder.rkt"
"private-yacc/grammar.rkt"
"private-yacc/yacc-helper.rkt"
"private-yacc/parser-actions.rkt"))
(require "private-lex/token.rkt"
"private-yacc/parser-actions.rkt"
mzlib/etc
mzlib/pretty
syntax/readerr)
(provide parser)
;; convert-parse-table : (vectorof (listof (cons/c gram-sym? action?))) ->
;; (vectorof (symbol runtime-action hashtable))
(define-for-syntax (convert-parse-table table)
(list->vector
(map
(lambda (state-entry)
(let ((ht (make-hasheq)))
(for-each
(lambda (gs/action)
(hash-set! ht
(gram-sym-symbol (car gs/action))
(action->runtime-action (cdr gs/action))))
state-entry)
ht))
(vector->list table))))
(define-syntax (parser stx)
(syntax-case stx ()
((_ args ...)
(let ((arg-list (syntax->list (syntax (args ...))))
(src-pos #f)
(debug #f)
(error #f)
(tokens #f)
(start #f)
(end #f)
(precs #f)
(suppress #f)
(grammar #f)
(yacc-output #f))
(for-each
(lambda (arg)
(syntax-case* arg (debug error tokens start end precs grammar
suppress src-pos yacc-output)
(lambda (a b)
(eq? (syntax-e a) (syntax-e b)))
((debug filename)
(cond
((not (string? (syntax-e (syntax filename))))
(raise-syntax-error
#f
"Debugging filename must be a string"
stx
(syntax filename)))
(debug
(raise-syntax-error #f "Multiple debug declarations" stx))
(else
(set! debug (syntax-e (syntax filename))))))
((suppress)
(set! suppress #t))
((src-pos)
(set! src-pos #t))
((error expression)
(if error
(raise-syntax-error #f "Multiple error declarations" stx)
(set! error (syntax expression))))
((tokens def ...)
(begin
(when tokens
(raise-syntax-error #f "Multiple tokens declarations" stx))
(let ((defs (syntax->list (syntax (def ...)))))
(for-each
(lambda (d)
(unless (identifier? d)
(raise-syntax-error
#f
"Token-group name must be an identifier"
stx
d)))
defs)
(set! tokens defs))))
((start symbol ...)
(let ((symbols (syntax->list (syntax (symbol ...)))))
(for-each
(lambda (sym)
(unless (identifier? sym)
(raise-syntax-error #f
"Start symbol must be a symbol"
stx
sym)))
symbols)
(when start
(raise-syntax-error #f "Multiple start declarations" stx))
(when (null? symbols)
(raise-syntax-error #f
"Missing start symbol"
stx
arg))
(set! start symbols)))
((end symbols ...)
(let ((symbols (syntax->list (syntax (symbols ...)))))
(for-each
(lambda (sym)
(unless (identifier? sym)
(raise-syntax-error #f
"End token must be a symbol"
stx
sym)))
symbols)
(let ((d (duplicate-list? (map syntax-e symbols))))
(when d
(raise-syntax-error
#f
(format "Duplicate end token definition for ~a" d)
stx
arg))
(when (null? symbols)
(raise-syntax-error
#f
"end declaration must contain at least 1 token"
stx
arg))
(when end
(raise-syntax-error #f "Multiple end declarations" stx))
(set! end symbols))))
((precs decls ...)
(if precs
(raise-syntax-error #f "Multiple precs declarations" stx)
(set! precs (syntax/loc arg (decls ...)))))
((grammar prods ...)
(if grammar
(raise-syntax-error #f "Multiple grammar declarations" stx)
(set! grammar (syntax/loc arg (prods ...)))))
((yacc-output filename)
(cond
((not (string? (syntax-e (syntax filename))))
(raise-syntax-error #f
"Yacc-output filename must be a string"
stx
(syntax filename)))
(yacc-output
(raise-syntax-error #f "Multiple yacc-output declarations" stx))
(else
(set! yacc-output (syntax-e (syntax filename))))))
(_ (raise-syntax-error #f "argument must match (debug filename), (error expression), (tokens def ...), (start non-term), (end tokens ...), (precs decls ...), or (grammar prods ...)" stx arg))))
(syntax->list (syntax (args ...))))
(unless tokens
(raise-syntax-error #f "missing tokens declaration" stx))
(unless error
(raise-syntax-error #f "missing error declaration" stx))
(unless grammar
(raise-syntax-error #f "missing grammar declaration" stx))
(unless end
(raise-syntax-error #f "missing end declaration" stx))
(unless start
(raise-syntax-error #f "missing start declaration" stx))
(let-values (((table all-term-syms actions check-syntax-fix)
(build-parser (if debug debug "")
src-pos
suppress
tokens
start
end
precs
grammar)))
(when (and yacc-output (not (string=? yacc-output "")))
(with-handlers [(exn:fail:filesystem?
(lambda (e)
(eprintf
"Cannot write yacc-output to file \"~a\"\n"
yacc-output)))]
(call-with-output-file yacc-output
(lambda (port)
(display-yacc (syntax->datum grammar)
tokens
(map syntax->datum start)
(if precs
(syntax->datum precs)
#f)
port))
#:exists 'truncate)))
(with-syntax ((check-syntax-fix check-syntax-fix)
(err error)
(ends end)
(starts start)
(debug debug)
(table (convert-parse-table table))
(all-term-syms all-term-syms)
(actions actions)
(src-pos src-pos))
(syntax
(begin
check-syntax-fix
(parser-body debug err (quote starts) (quote ends) table all-term-syms actions src-pos)))))))
(_
(raise-syntax-error #f
"parser must have the form (parser args ...)"
stx))))
(define (reduce-stack stack num ret-vals src-pos)
(cond
((> num 0)
(let* ((top-frame (car stack))
(ret-vals
(if src-pos
(cons (stack-frame-value top-frame)
(cons (stack-frame-start-pos top-frame)
(cons (stack-frame-end-pos top-frame)
ret-vals)))
(cons (stack-frame-value top-frame) ret-vals))))
(reduce-stack (cdr stack) (sub1 num) ret-vals src-pos)))
(else (values stack ret-vals))))
;; extract-helper : (symbol or make-token) any any -> symbol any any any
(define (extract-helper tok v1 v2)
(cond
((symbol? tok)
(values tok #f v1 v2))
((token? tok)
(values (real-token-name tok) (real-token-value tok) v1 v2))
(else (raise-argument-error 'parser
"(or/c symbol? token?)"
0
tok))))
;; well-formed-position-token?: any -> boolean
;; Returns true if pt is a position token whose position-token-token
;; is itself a token or a symbol.
;; This is meant to help raise more precise error messages when
;; a tokenizer produces an erroneous position-token wrapped twice.
;; (as often happens when omitting return-without-pos).
(define (well-formed-token-field? t)
(or (symbol? t)
(token? t)))
(define (well-formed-position-token? pt)
(and (position-token? pt)
(well-formed-token-field? (position-token-token pt))))
(define (well-formed-srcloc-token? st)
(and (srcloc-token? st)
(well-formed-token-field? (srcloc-token-token st))))
;; extract-src-pos : position-token -> symbol any any any
(define (extract-src-pos ip)
(unless (well-formed-position-token? ip)
(raise-argument-error 'parser
"well-formed-position-token?"
0
ip))
(extract-helper (position-token-token ip)
(position-token-start-pos ip)
(position-token-end-pos ip)))
(define (extract-srcloc ip)
(unless (well-formed-srcloc-token? ip)
(raise-argument-error 'parser
"well-formed-srcloc-token?"
0
ip))
(let ([loc (srcloc-token-srcloc ip)])
(extract-helper (srcloc-token-token ip)
(position-token (srcloc-position loc) (srcloc-line loc) (srcloc-column loc))
(position-token (+ (srcloc-position loc) (srcloc-span loc)) #f #f))))
;; extract-no-src-pos : (symbol or make-token) -> symbol any any any
(define (extract-no-src-pos ip)
(extract-helper ip #f #f))
(define-struct stack-frame (state value start-pos end-pos) #:inspector (make-inspector))
(define (make-empty-stack i) (list (make-stack-frame i #f #f #f)))
;; The table is a vector that maps each state to a hash-table that maps a
;; terminal symbol to either an accept, shift, reduce, or goto structure.
; We encode the structures according to the runtime-action data definition in
;; parser-actions.rkt
(define (parser-body debug? err starts ends table all-term-syms actions src-pos)
(local ((define extract
(if src-pos
extract-src-pos
extract-no-src-pos))
(define (fix-error stack tok val start-pos end-pos get-token)
(when debug? (pretty-print stack))
(local ((define (remove-input tok val start-pos end-pos)
(if (memq tok ends)
(raise-read-error "parser: Cannot continue after error"
#f #f #f #f #f)
(let ((a (find-action stack tok val start-pos end-pos)))
(cond
((runtime-shift? a)
;; (printf "shift:~a\n" (runtime-shift-state a))
(cons (make-stack-frame (runtime-shift-state a)
val
start-pos
end-pos)
stack))
(else
;; (printf "discard input:~a\n" tok)
(let-values (((tok val start-pos end-pos)
(extract (get-token))))
(remove-input tok val start-pos end-pos))))))))
(let remove-states ()
(let ((a (find-action stack 'error #f start-pos end-pos)))
(cond
((runtime-shift? a)
;; (printf "shift:~a\n" (runtime-shift-state a))
(set! stack
(cons
(make-stack-frame (runtime-shift-state a)
#f
start-pos
end-pos)
stack))
(remove-input tok val start-pos end-pos))
(else
;; (printf "discard state:~a\n" (car stack))
(cond
((< (length stack) 2)
(raise-read-error "parser: Cannot continue after error"
#f #f #f #f #f))
(else
(set! stack (cdr stack))
(remove-states)))))))))
(define (find-action stack tok val start-pos end-pos)
(unless (hash-ref all-term-syms
tok
#f)
(if src-pos
(err #f tok val start-pos end-pos)
(err #f tok val))
(raise-read-error (format "parser: got token of unknown type ~a" tok)
#f #f #f #f #f))
(hash-ref (vector-ref table (stack-frame-state (car stack)))
tok
#f))
(define (make-parser start-number)
(lambda (get-token)
(unless (and (procedure? get-token)
(procedure-arity-includes? get-token 0))
(error 'get-token "expected a nullary procedure, got ~e" get-token))
(let parsing-loop ((stack (make-empty-stack start-number))
(ip (get-token)))
(let-values (((tok val start-pos end-pos)
(extract ip)))
(let ((action (find-action stack tok val start-pos end-pos)))
(cond
((runtime-shift? action)
;; (printf "shift:~a\n" (runtime-shift-state action))
(parsing-loop (cons (make-stack-frame (runtime-shift-state action)
val
start-pos
end-pos)
stack)
(get-token)))
((runtime-reduce? action)
;; (printf "reduce:~a\n" (runtime-reduce-prod-num action))
(let-values (((new-stack args)
(reduce-stack stack
(runtime-reduce-rhs-length action)
null
src-pos)))
(let ((goto
(runtime-goto-state
(hash-ref
(vector-ref table (stack-frame-state (car new-stack)))
(runtime-reduce-lhs action)))))
(parsing-loop
(cons
(if src-pos
(make-stack-frame
goto
(apply (vector-ref actions (runtime-reduce-prod-num action)) args)
(if (null? args) start-pos (cadr args))
(if (null? args)
end-pos
(list-ref args (- (* (runtime-reduce-rhs-length action) 3) 1))))
(make-stack-frame
goto
(apply (vector-ref actions (runtime-reduce-prod-num action)) args)
#f
#f))
new-stack)
ip))))
((runtime-accept? action)
;; (printf "accept\n")
(stack-frame-value (car stack)))
(else
(if src-pos
(err #t tok val start-pos end-pos)
(err #t tok val))
(parsing-loop (fix-error stack tok val start-pos end-pos get-token)
(get-token))))))))))
(cond
((null? (cdr starts)) (make-parser 0))
(else
(let loop ((l starts)
(i 0))
(cond
((null? l) null)
(else (cons (make-parser i) (loop (cdr l) (add1 i))))))))))

11
br-parser-tools/br-parser-tools-lib/info.rkt
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#lang info
(define collection 'multi)
(define deps '("scheme-lib"
"base"
"compatibility-lib"))
(define build-deps '("rackunit-lib"))
(define pkg-desc "implementation (no documentation) part of \"br-parser-tools\"")
(define pkg-authors '(mflatt))

11
br-parser-tools/br-parser-tools/LICENSE.txt
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parser-tools
Copyright (c) 2010-2014 PLT Design Inc.
This package is distributed under the GNU Lesser General Public
License (LGPL). This means that you can link this package into proprietary
applications, provided you follow the rules stated in the LGPL. You
can also modify this package; if you distribute a modified version,
you must distribute it under the terms of the LGPL, which in
particular means that you must release the source code for the
modified software. See http://www.gnu.org/copyleft/lesser.html
for more information.

12
br-parser-tools/br-parser-tools/info.rkt
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#lang info
(define collection 'multi)
(define deps '("br-parser-tools-lib"
"br-parser-tools-doc"))
(define implies '("br-parser-tools-lib"
"br-parser-tools-doc"))
(define pkg-desc "Lex- and Yacc-style parsing tools")
(define pkg-authors '(mflatt))
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