You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
277 lines
11 KiB
Scheme
277 lines
11 KiB
Scheme
(module lex mzscheme
|
|
|
|
;; Provides the syntax used to create lexers and the functions needed to
|
|
;; create and use the buffer that the lexer reads from. See doc.txt.
|
|
|
|
(require-for-syntax "private-lex/generate-code.ss"
|
|
"private-lex/structs.ss")
|
|
|
|
(require (lib "readerr.ss" "syntax")
|
|
"private-lex/token.ss"
|
|
(lib "cffi.ss" "compiler"))
|
|
|
|
(provide lexer lexer-src-pos define-lex-abbrev define-lex-abbrevs
|
|
position-offset position-line position-col position?
|
|
define-tokens define-empty-tokens token-name token-value token? file-path)
|
|
|
|
(define file-path (make-parameter #f))
|
|
|
|
#;(define-syntaxes (lexer-exp lexer-src-pos-exp)
|
|
(let ((build-lexer
|
|
(lambda (wrap?)
|
|
(lambda (stx)
|
|
(syntax-case stx ()
|
|
((_)
|
|
(raise-syntax-error #f "empty lexer is not allowed" stx))
|
|
((_ re-act ...)
|
|
(begin
|
|
(for-each
|
|
(lambda (x)
|
|
(syntax-case x ()
|
|
((re act) (void))
|
|
(_ (raise-syntax-error 'lexer
|
|
"expects regular expression / action pairs"
|
|
x))))
|
|
(syntax->list (syntax (re-act ...))))
|
|
(let ((table (generate-table (syntax (re-act ...)) stx)))
|
|
(with-syntax ((code (compile-table table))
|
|
(actions-stx `(vector ,@(vector->list (table-actions table))))
|
|
(wrap? wrap?))
|
|
(syntax
|
|
(compiled-lexer-body code actions-stx wrap?)))))))))))
|
|
(values
|
|
(build-lexer #f)
|
|
(build-lexer #t))))
|
|
|
|
(define-syntaxes (lexer lexer-src-pos)
|
|
(let ((build-lexer
|
|
(lambda (wrap?)
|
|
(lambda (stx)
|
|
(syntax-case stx ()
|
|
((_)
|
|
(raise-syntax-error #f "empty lexer is not allowed" stx))
|
|
((_ re-act ...)
|
|
(begin
|
|
(for-each
|
|
(lambda (x)
|
|
(syntax-case x ()
|
|
((re act) (void))
|
|
(_ (raise-syntax-error 'lexer
|
|
"expects regular expression / action pairs"
|
|
x))))
|
|
(syntax->list (syntax (re-act ...))))
|
|
(let* ((re-act-lst (syntax->list (syntax (re-act ...))))
|
|
(spec-act (let loop ((lst re-act-lst))
|
|
(cond
|
|
((null? lst)
|
|
#'(void))
|
|
(else
|
|
(syntax-case (car lst) ()
|
|
(((special) act)
|
|
(eq? (syntax-e (syntax special)) 'special)
|
|
(syntax act))
|
|
(_ (loop (cdr lst))))))))
|
|
(re-act-lst (let loop ((lst re-act-lst))
|
|
(cond
|
|
((null? lst)
|
|
null)
|
|
(else
|
|
(syntax-case (car lst) ()
|
|
(((special) act)
|
|
(eq? (syntax-e (syntax special)) 'special)
|
|
(loop (cdr lst)))
|
|
(_ (cons (car lst) (loop (cdr lst)))))))))
|
|
(spec-act (datum->syntax-object
|
|
spec-act
|
|
`(lambda (start-pos end-pos lexeme return-without-pos input-port)
|
|
,spec-act)
|
|
spec-act)))
|
|
(let ((table (generate-table re-act-lst stx)))
|
|
(with-syntax ((start-state-stx (table-start table))
|
|
(trans-table-stx (table-trans table))
|
|
(eof-table-stx (table-eof table))
|
|
(no-lookahead-stx (table-no-lookahead table))
|
|
(actions-stx `(vector ,@(vector->list (table-actions table))))
|
|
(spec-act-stx spec-act)
|
|
(wrap? wrap?))
|
|
(syntax
|
|
(lexer-body start-state-stx
|
|
trans-table-stx
|
|
eof-table-stx
|
|
actions-stx
|
|
no-lookahead-stx
|
|
spec-act-stx
|
|
wrap?))))))))))))
|
|
(values
|
|
(build-lexer #f)
|
|
(build-lexer #t))))
|
|
|
|
(define-syntax (define-lex-abbrev stx)
|
|
(syntax-case stx ()
|
|
((_ name re)
|
|
(syntax
|
|
(define-syntax name
|
|
(make-lex-abbrev (quote-syntax re)))))
|
|
(_
|
|
(raise-syntax-error
|
|
#f
|
|
"Form should be (define-lex-abbrev name re)"
|
|
stx))))
|
|
|
|
(define-syntax (define-lex-abbrevs stx)
|
|
(syntax-case stx ()
|
|
((_ x ...)
|
|
(let* ((abbrev (syntax->list (syntax (x ...))))
|
|
(r (map (lambda (a)
|
|
(syntax-case a ()
|
|
((name re)
|
|
(identifier? (syntax name))
|
|
(syntax (define-lex-abbrev name re)))
|
|
(_ (raise-syntax-error
|
|
'Lexer-abbreviation
|
|
"Form should be (identifier value)"
|
|
a))))
|
|
abbrev)))
|
|
(datum->syntax-object
|
|
#'here
|
|
(cons 'begin r)
|
|
stx)))
|
|
(_
|
|
(raise-syntax-error
|
|
#f
|
|
"Form should be (define-lex-abbrevs (name re) ...)"
|
|
stx))))
|
|
|
|
#;(define (compiled-lexer-body lexer actions wrap?)
|
|
(lambda (ip)
|
|
(unless (input-port? ip)
|
|
(raise-type-error
|
|
'lexer
|
|
"input-port"
|
|
0
|
|
ip))
|
|
(let ((first-pos (get-position ip)))
|
|
(let-values (((longest-match-length length longest-match-action)
|
|
(lexer ip peek-string)))
|
|
(do-match ip first-pos longest-match-length length (vector-ref actions longest-match-action) wrap?)))))
|
|
|
|
(define (lexer-body start-state trans-table eof-table actions no-lookahead special-action wrap?)
|
|
(lambda (ip)
|
|
(unless (input-port? ip)
|
|
(raise-type-error
|
|
'lexer
|
|
"input-port"
|
|
0
|
|
ip))
|
|
(let ((first-pos (get-position ip))
|
|
(first-char (peek-char-or-special ip 0)))
|
|
(cond
|
|
((eq? 'special first-char)
|
|
(let* ((val (read-char-or-special ip))
|
|
(end-pos (get-position ip)))
|
|
(cond
|
|
(wrap?
|
|
(let/ec ret
|
|
(list (special-action first-pos
|
|
end-pos
|
|
val
|
|
ret
|
|
ip)
|
|
first-pos
|
|
end-pos)))
|
|
(else
|
|
(special-action first-pos
|
|
end-pos
|
|
val
|
|
id
|
|
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 characters have been read
|
|
;; including the one just read
|
|
(length 1)
|
|
;; how many characters are in the longest match
|
|
(longest-match-length 1))
|
|
(let ((next-state
|
|
(cond
|
|
((eof-object? char)
|
|
(vector-ref eof-table state))
|
|
((eq? char 'special)
|
|
#f)
|
|
(else
|
|
(vector-ref
|
|
trans-table
|
|
(+ (char->integer char) (* 256 state)))))))
|
|
(cond
|
|
((not next-state)
|
|
(do-match ip first-pos longest-match-length length longest-match-action wrap?))
|
|
((vector-ref no-lookahead next-state)
|
|
(let ((act (vector-ref actions next-state)))
|
|
(do-match ip
|
|
first-pos
|
|
(if act length longest-match-length)
|
|
length
|
|
(if act act longest-match-action)
|
|
wrap?)))
|
|
(else
|
|
(let ((act (vector-ref actions next-state)))
|
|
(lexer-loop next-state
|
|
(peek-char-or-special ip length)
|
|
(if act
|
|
act
|
|
longest-match-action)
|
|
(add1 length)
|
|
(if act
|
|
length
|
|
longest-match-length))))))))))))
|
|
|
|
(define id (lambda (x) x))
|
|
|
|
(define (do-match lb first-pos longest-match-length length longest-match-action wrap?)
|
|
(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))
|
|
(end-pos (get-position lb)))
|
|
(cond
|
|
(wrap?
|
|
(let/ec ret
|
|
(list (longest-match-action
|
|
first-pos
|
|
end-pos
|
|
match
|
|
ret
|
|
lb)
|
|
first-pos
|
|
end-pos)))
|
|
(else
|
|
(longest-match-action
|
|
first-pos
|
|
end-pos
|
|
match
|
|
id
|
|
lb)))))
|
|
|
|
|
|
(define-struct position (offset line col))
|
|
(define (get-position ip)
|
|
(let-values (((line col off) (port-next-location ip)))
|
|
(make-position off line col)))
|
|
|
|
)
|