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.
774 lines
34 KiB
Racket
774 lines
34 KiB
Racket
|
|
;; This module implements a parser form like the 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 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.
|
|
|
|
(module cfg-parser mzscheme
|
|
(require parser-tools/yacc
|
|
parser-tools/lex
|
|
mzlib/list
|
|
mzlib/etc)
|
|
(require-for-syntax syntax/boundmap
|
|
mzlib/list
|
|
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))
|
|
|
|
;; Represents the thread scheduler:
|
|
(define-struct tasks (active active-back waits multi-waits cache progress?))
|
|
|
|
(define-for-syntax make-token-identifier-mapping make-hash-table)
|
|
(define-for-syntax token-identifier-mapping-get
|
|
(case-lambda
|
|
[(t tok)
|
|
(hash-table-get t (syntax-e tok))]
|
|
[(t tok fail)
|
|
(hash-table-get t (syntax-e tok) fail)]))
|
|
(define-for-syntax token-identifier-mapping-put!
|
|
(lambda (t tok v)
|
|
(hash-table-put! t (syntax-e tok) v)))
|
|
(define-for-syntax token-identifier-mapping-map
|
|
(lambda (t f)
|
|
(hash-table-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 depth end success-k fail-k
|
|
max-depth tasks)
|
|
(letrec ([mk-got-k
|
|
(lambda (success-k fail-k)
|
|
(lambda (val stream depth max-depth tasks next1-k)
|
|
(if simple-a?
|
|
(parse-b val stream 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 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 depth max-depth tasks next-k)
|
|
(success-k val stream 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 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 depth end success-k fail-k max-depth tasks)
|
|
(parallel-or (lambda (success-k fail-k max-depth tasks)
|
|
(parse-a stream depth end success-k fail-k max-depth tasks))
|
|
(lambda (success-k fail-k max-depth tasks)
|
|
(parse-b stream 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 depth max-depth tasks next-k)
|
|
(report-answer answer-key
|
|
max-depth
|
|
tasks
|
|
(list val stream 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 depth max-depth tasks next-k)
|
|
(let ([tasks (if immediate-next?
|
|
(queue-next next-k tasks)
|
|
tasks)])
|
|
(success-k val stream 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 depth end success-k fail-k max-depth tasks)
|
|
(letrec ([mk-got-k
|
|
(lambda (success-k fail-k)
|
|
(lambda (val stream depth max-depth tasks next-k)
|
|
(success-k val stream 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 depth end success-k fail-k max-depth tasks)))])
|
|
(parse-a stream 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
|
|
(opt-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-table-get (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-table-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-table-get (tasks-multi-waits tasks) answer-key (lambda () null))])
|
|
(hash-table-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 depth next-k) (apply values val)])
|
|
(success-k val stream depth max-depth tasks next-k)))
|
|
(deadlock-k max-depth tasks))))])
|
|
(if multi?
|
|
(hash-table-put! (tasks-multi-waits tasks) answer-key
|
|
(cons wait (hash-table-get (tasks-multi-waits tasks) answer-key
|
|
(lambda () null))))
|
|
(hash-table-put! (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-table-count (tasks-multi-waits tasks)))
|
|
(error 'swap-task "Deadlock")
|
|
(swap-task max-depth
|
|
(make-tasks (apply
|
|
append
|
|
(hash-table-map (tasks-multi-waits tasks)
|
|
(lambda (k l)
|
|
(map (lambda (v) (v #f)) l))))
|
|
(tasks-active-back tasks)
|
|
(tasks-waits tasks)
|
|
(make-hash-table)
|
|
(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 0 0 0))
|
|
(define-for-syntax no-pos
|
|
(let ([npv ((syntax-local-certifier) #'no-pos-val)])
|
|
(lambda (stx) npv)))
|
|
|
|
;; Builds a matcher for a particular alternative
|
|
(define-for-syntax (build-match nts toks pat handle $ctx)
|
|
(let loop ([pat pat]
|
|
[pos 1])
|
|
(if (null? pat)
|
|
#`(success-k #,handle stream depth max-depth tasks
|
|
(lambda (success-k fail-k max-depth tasks)
|
|
(fail-k max-depth tasks)))
|
|
(let ([id (datum->syntax-object (car pat)
|
|
(string->symbol (format "$~a" pos)))]
|
|
[id-start-pos (datum->syntax-object (car pat)
|
|
(string->symbol (format "$~a-start-pos" pos)))]
|
|
[id-end-pos (datum->syntax-object (car pat)
|
|
(string->symbol (format "$~a-end-pos" 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)
|
|
(lambda (#,id stream depth end success-k fail-k max-depth tasks)
|
|
(let-syntax ([#,id-start-pos no-pos]
|
|
[#,id-end-pos no-pos])
|
|
#,(loop (cdr pat) (add1 pos))))
|
|
stream 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 ([#,id (tok-val (car stream))]
|
|
[stream (cdr stream)]
|
|
[depth (add1 depth)])
|
|
(let ([max-depth (max max-depth depth)])
|
|
(let-syntax ([#,id-start-pos no-pos]
|
|
[#,id-end-pos no-pos])
|
|
#,(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 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-table-get (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-table-put! (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 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-table-get (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-table-put! (tasks-cache tasks) result-key #t)
|
|
(hash-table-put! (tasks-cache tasks) table-key
|
|
(lambda (success-k fail-k max-depth tasks)
|
|
(success-k val stream depth max-depth tasks next-k)))
|
|
(report-answer-all answer-key
|
|
max-depth
|
|
tasks
|
|
(list val stream depth next-k)
|
|
(lambda (max-depth tasks)
|
|
(success-k val stream depth max-depth tasks next-k))))])))]
|
|
[new-fail-k
|
|
(lambda (max-depth tasks)
|
|
#;(printf "Failure ~a\n" table-key)
|
|
(hash-table-put! (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)))])))))
|
|
|
|
(define-syntax (cfg-parser stx)
|
|
(syntax-case stx ()
|
|
[(_ clause ...)
|
|
(let ([clauses (syntax->list #'(clause ...))])
|
|
(let-values ([(start grammar cfg-error parser-clauses)
|
|
(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]
|
|
[parser-clauses null])
|
|
(if (null? clauses)
|
|
(values cfg-start
|
|
cfg-grammar
|
|
cfg-error
|
|
(reverse parser-clauses))
|
|
(syntax-case (car clauses) (start error grammar)
|
|
[(start tok)
|
|
(loop (cdr clauses) #'tok cfg-grammar cfg-error parser-clauses)]
|
|
[(error expr)
|
|
(loop (cdr clauses) cfg-start cfg-grammar #'expr 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 $ctxs)
|
|
(define info (bound-identifier-mapping-get nts nt))
|
|
(list nt
|
|
#`(let ([key (gensym '#,nt)])
|
|
(lambda (stream depth end success-k fail-k max-depth tasks)
|
|
(parse-nt/share
|
|
key #,(car info) '#,(cadr info) stream depth end
|
|
max-depth tasks
|
|
success-k fail-k
|
|
(lambda (end max-depth tasks success-k fail-k)
|
|
#,(let loop ([pats pats]
|
|
[handles (syntax->list handles)]
|
|
[$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 depth end success-k fail-k max-depth tasks)
|
|
#,(build-match nts
|
|
toks
|
|
(car pats)
|
|
(car handles)
|
|
(car $ctxs)))
|
|
(lambda (stream depth end success-k fail-k max-depth tasks)
|
|
#,(loop (cdr pats)
|
|
(cdr handles)
|
|
(cdr $ctxs)
|
|
(cdr simple?s)))
|
|
stream depth end success-k fail-k max-depth tasks)))))))))
|
|
nt-ids
|
|
patss
|
|
(syntax->list #'(((begin handle0 handle ...) ...) ...))
|
|
(syntax->list #'((handle0 ...) ...)))
|
|
cfg-error
|
|
(list*
|
|
(with-syntax ([((tok tok-id . $e) ...)
|
|
(token-identifier-mapping-map toks
|
|
(lambda (k v)
|
|
(list* k
|
|
(car v)
|
|
(if (cdr v)
|
|
#f
|
|
'$1))))])
|
|
#`(grammar (start [() null]
|
|
[(atok start) (cons $1 $2)])
|
|
(atok [(tok) (make-tok 'tok-id 'tok $e)] ...)))
|
|
#`(start start)
|
|
parser-clauses)))]
|
|
[(grammar . _)
|
|
(raise-syntax-error
|
|
#f
|
|
"bad grammar clause"
|
|
stx
|
|
(car clauses))]
|
|
[_else
|
|
(loop (cdr clauses)
|
|
cfg-start
|
|
cfg-grammar
|
|
cfg-error
|
|
(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 depth max-depth tasks next)
|
|
(if (null? stream)
|
|
val
|
|
(next success-k fail-k max-depth tasks)))]
|
|
[fail-k (lambda (max-depth tasks)
|
|
(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))
|
|
(error
|
|
'cfg-parse
|
|
"failed at ~a"
|
|
(tok-val bad-tok)))))])
|
|
(#,start tok-list 0
|
|
(length tok-list)
|
|
success-k
|
|
fail-k
|
|
0 (make-tasks null null
|
|
(make-hash-table) (make-hash-table)
|
|
(make-hash-table 'equal) #t)))))))))]))
|
|
|
|
#|
|
|
;; 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 '|:|)]
|
|
[(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)]])))
|
|
|
|
(define (result)
|
|
(let ([p (open-input-string #;"+*|-|-*|+**" #;"-|+*|+**"
|
|
#;"+*|+**|-" #;"-|-*|-|-*"
|
|
#;"-|-*|-|-**|-|-*|-|-**"
|
|
"-|-*|-|-**|-|-*|-|-***|-|-*|-|-**|-|-*|-|-****|-|-*|-|-**|-|-*|-|-***\
|
|
|-|-*|-|-**|-|-*|-|-*****|-|-*|-|-**|-|-*|-|-***|-|-*|-|-**|-|-*|-|-****|\
|
|
-|-*|-|-**|-|-*|-|-***|-|-*|-|-**|-|-*|-|-*****"
|
|
;; This one fails:
|
|
#;"+*")])
|
|
(time (parse (lambda () (lex p))))))
|
|
|#
|
|
)
|