consolidate
parent
c7601a8964
commit
9e2e7f04c8
@ -1,924 +1,3 @@
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#lang racket/base
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;; This module implements a parser form like the br-parser-tools's
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;; `parser', except that it works on an arbitrary CFG (returning
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;; the first sucecssful parse).
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;; I'm pretty sure that this is an implementation of Earley's
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;; algorithm.
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;; To a first approximation, it's a backtracking parser. Alternative
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;; for a non-terminal are computed in parallel, and multiple attempts
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;; to compute the same result block until the first one completes. If
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;; you get into deadlock, such as when trying to match
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;; <foo> := <foo>
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;; then it means that there's no successful parse, so everything
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;; that's blocked fails.
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;; A cache holds the series of results for a particular non-terminal
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;; at a particular starting location. (A series is used, instead of a
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;; sinlge result, for backtracking.) Otherwise, the parser uses
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;; backtracking search. Backtracking is implemented through explicit
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;; success and failure continuations. Multiple results for a
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;; particular nonterminal and location are kept only when they have
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;; different lengths. (Otherwise, in the spirit of finding one
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;; successful parse, only the first result is kept.)
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;; The br-parser-tools's `parse' is used to transform tokens in the
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;; grammar to tokens specific to this parser. In other words, this
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;; parser uses `parser' so that it doesn't have to know anything about
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;; tokens.
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;;
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(require br-parser-tools/yacc
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br-parser-tools/lex)
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(require (for-syntax racket/base
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syntax/boundmap
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br-parser-tools/private-lex/token-syntax))
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(provide cfg-parser)
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;; A raw token, wrapped so that we can recognize it:
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(define-struct tok (name orig-name val start end))
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;; Represents the thread scheduler:
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(define-struct tasks (active active-back waits multi-waits cache progress?))
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(define-for-syntax make-token-identifier-mapping make-hasheq)
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(define-for-syntax token-identifier-mapping-get
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(case-lambda
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[(t tok)
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(hash-ref t (syntax-e tok))]
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[(t tok fail)
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(hash-ref t (syntax-e tok) fail)]))
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(define-for-syntax token-identifier-mapping-put!
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(lambda (t tok v)
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(hash-set! t (syntax-e tok) v)))
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(define-for-syntax token-identifier-mapping-map
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(lambda (t f)
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(hash-map t f)))
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;; Used to calculate information on the grammar, such as whether
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;; a particular non-terminal is "simple" instead of recursively defined.
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(define-for-syntax (nt-fixpoint nts proc nt-ids patss)
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(define (ormap-all val f as bs)
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(cond
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[(null? as) val]
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[else (ormap-all (or (f (car as) (car bs)) val)
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f
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(cdr as) (cdr bs))]))
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(let loop ()
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(when (ormap-all #f
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(lambda (nt pats)
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(let ([old (bound-identifier-mapping-get nts nt)])
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(let ([new (proc nt pats old)])
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(if (equal? old new)
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#f
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(begin
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(bound-identifier-mapping-put! nts nt new)
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#t)))))
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nt-ids patss)
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(loop))))
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;; Tries parse-a followed by parse-b. If parse-a is not simple,
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;; then after parse-a succeeds once, we parallelize parse-b
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;; and trying a second result for parse-a.
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(define (parse-and simple-a? parse-a parse-b
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stream last-consumed-token depth end success-k fail-k
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max-depth tasks)
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(letrec ([mk-got-k
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(lambda (success-k fail-k)
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(lambda (val stream last-consumed-token depth max-depth tasks next1-k)
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(if simple-a?
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(parse-b val stream last-consumed-token depth end
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(mk-got2-k success-k fail-k next1-k)
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(mk-fail2-k success-k fail-k next1-k)
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max-depth tasks)
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(parallel-or
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(lambda (success-k fail-k max-depth tasks)
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(parse-b val stream last-consumed-token depth end
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success-k fail-k
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max-depth tasks))
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(lambda (success-k fail-k max-depth tasks)
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(next1-k (mk-got-k success-k fail-k)
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fail-k max-depth tasks))
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success-k fail-k max-depth tasks))))]
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[mk-got2-k
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(lambda (success-k fail-k next1-k)
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(lambda (val stream last-consumed-token depth max-depth tasks next-k)
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(success-k val stream last-consumed-token depth max-depth tasks
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(lambda (success-k fail-k max-depth tasks)
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(next-k (mk-got2-k success-k fail-k next1-k)
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(mk-fail2-k success-k fail-k next1-k)
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max-depth tasks)))))]
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[mk-fail2-k
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(lambda (success-k fail-k next1-k)
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(lambda (max-depth tasks)
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(next1-k (mk-got-k success-k fail-k)
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fail-k
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max-depth
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tasks)))])
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(parse-a stream last-consumed-token depth end
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(mk-got-k success-k fail-k)
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fail-k
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max-depth tasks)))
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;; Parallel or for non-terminal alternatives
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(define (parse-parallel-or parse-a parse-b stream last-consumed-token depth end success-k fail-k max-depth tasks)
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(parallel-or (lambda (success-k fail-k max-depth tasks)
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(parse-a stream last-consumed-token depth end success-k fail-k max-depth tasks))
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(lambda (success-k fail-k max-depth tasks)
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(parse-b stream last-consumed-token depth end success-k fail-k max-depth tasks))
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success-k fail-k max-depth tasks))
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;; Generic parallel-or
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(define (parallel-or parse-a parse-b success-k fail-k max-depth tasks)
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(define answer-key (gensym))
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(letrec ([gota-k
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(lambda (val stream last-consumed-token depth max-depth tasks next-k)
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(report-answer answer-key
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max-depth
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tasks
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(list val stream last-consumed-token depth next-k)))]
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[faila-k
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(lambda (max-depth tasks)
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(report-answer answer-key
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max-depth
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tasks
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null))])
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(let* ([tasks (queue-task
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tasks
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(lambda (max-depth tasks)
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(parse-a gota-k
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faila-k
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max-depth tasks)))]
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[tasks (queue-task
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tasks
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(lambda (max-depth tasks)
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(parse-b gota-k
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faila-k
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max-depth tasks)))]
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[queue-next (lambda (next-k tasks)
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(queue-task tasks
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(lambda (max-depth tasks)
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(next-k gota-k
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faila-k
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max-depth tasks))))])
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(letrec ([mk-got-one
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(lambda (immediate-next? get-nth success-k)
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(lambda (val stream last-consumed-token depth max-depth tasks next-k)
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(let ([tasks (if immediate-next?
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(queue-next next-k tasks)
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tasks)])
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(success-k val stream last-consumed-token depth max-depth
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tasks
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(lambda (success-k fail-k max-depth tasks)
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(let ([tasks (if immediate-next?
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tasks
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(queue-next next-k tasks))])
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(get-nth max-depth tasks success-k fail-k)))))))]
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[get-first
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(lambda (max-depth tasks success-k fail-k)
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(wait-for-answer #f max-depth tasks answer-key
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(mk-got-one #t get-first success-k)
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(lambda (max-depth tasks)
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(get-second max-depth tasks success-k fail-k))
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#f))]
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[get-second
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(lambda (max-depth tasks success-k fail-k)
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(wait-for-answer #f max-depth tasks answer-key
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(mk-got-one #f get-second success-k)
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fail-k #f))])
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(get-first max-depth tasks success-k fail-k)))))
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;; Non-terminal alternatives where the first is "simple" can be done
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;; sequentially, which is simpler
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(define (parse-or parse-a parse-b
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stream last-consumed-token depth end success-k fail-k max-depth tasks)
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(letrec ([mk-got-k
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(lambda (success-k fail-k)
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(lambda (val stream last-consumed-token depth max-depth tasks next-k)
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(success-k val stream last-consumed-token depth
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max-depth tasks
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(lambda (success-k fail-k max-depth tasks)
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(next-k (mk-got-k success-k fail-k)
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(mk-fail-k success-k fail-k)
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max-depth tasks)))))]
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[mk-fail-k
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(lambda (success-k fail-k)
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(lambda (max-depth tasks)
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(parse-b stream last-consumed-token depth end success-k fail-k max-depth tasks)))])
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(parse-a stream last-consumed-token depth end
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(mk-got-k success-k fail-k)
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(mk-fail-k success-k fail-k)
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max-depth tasks)))
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;; Starts a thread
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(define queue-task
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(lambda (tasks t [progress? #t])
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(make-tasks (tasks-active tasks)
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(cons t (tasks-active-back tasks))
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(tasks-waits tasks)
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(tasks-multi-waits tasks)
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(tasks-cache tasks)
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(or progress? (tasks-progress? tasks)))))
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;; Reports an answer to a waiting thread:
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(define (report-answer answer-key max-depth tasks val)
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(let ([v (hash-ref (tasks-waits tasks) answer-key (lambda () #f))])
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(if v
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(let ([tasks (make-tasks (cons (v val)
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(tasks-active tasks))
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(tasks-active-back tasks)
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(tasks-waits tasks)
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(tasks-multi-waits tasks)
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(tasks-cache tasks)
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#t)])
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(hash-remove! (tasks-waits tasks) answer-key)
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(swap-task max-depth tasks))
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;; We have an answer ready too fast; wait
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(swap-task max-depth
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(queue-task tasks
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(lambda (max-depth tasks)
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(report-answer answer-key max-depth tasks val))
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#f)))))
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;; Reports an answer to multiple waiting threads:
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(define (report-answer-all answer-key max-depth tasks val k)
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(let ([v (hash-ref (tasks-multi-waits tasks) answer-key (lambda () null))])
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(hash-remove! (tasks-multi-waits tasks) answer-key)
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(let ([tasks (make-tasks (append (map (lambda (a) (a val)) v)
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(tasks-active tasks))
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(tasks-active-back tasks)
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(tasks-waits tasks)
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(tasks-multi-waits tasks)
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(tasks-cache tasks)
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#t)])
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(k max-depth tasks))))
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;; Waits for an answer; if `multi?' is #f, this is sole waiter, otherwise
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;; there might be many. Use wither #t or #f (and `report-answer' or
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;; `report-answer-all', resptively) consistently for a particular answer key.
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(define (wait-for-answer multi? max-depth tasks answer-key success-k fail-k deadlock-k)
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(let ([wait (lambda (val)
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(lambda (max-depth tasks)
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(if val
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(if (null? val)
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(fail-k max-depth tasks)
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(let-values ([(val stream last-consumed-token depth next-k) (apply values val)])
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(success-k val stream last-consumed-token depth max-depth tasks next-k)))
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(deadlock-k max-depth tasks))))])
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(if multi?
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(hash-set! (tasks-multi-waits tasks) answer-key
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(cons wait (hash-ref (tasks-multi-waits tasks) answer-key
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(lambda () null))))
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(hash-set! (tasks-waits tasks) answer-key wait))
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(let ([tasks (make-tasks (tasks-active tasks)
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(tasks-active-back tasks)
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(tasks-waits tasks)
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(tasks-multi-waits tasks)
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(tasks-cache tasks)
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#t)])
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(swap-task max-depth tasks))))
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;; Swap thread
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(define (swap-task max-depth tasks)
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;; Swap in first active:
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(if (null? (tasks-active tasks))
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(if (tasks-progress? tasks)
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(swap-task max-depth
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(make-tasks (reverse (tasks-active-back tasks))
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null
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(tasks-waits tasks)
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(tasks-multi-waits tasks)
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(tasks-cache tasks)
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#f))
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;; No progress, so issue failure for all multi-waits
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(if (zero? (hash-count (tasks-multi-waits tasks)))
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(error 'swap-task "Deadlock")
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(swap-task max-depth
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(make-tasks (apply
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append
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(hash-map (tasks-multi-waits tasks)
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(lambda (k l)
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(map (lambda (v) (v #f)) l))))
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(tasks-active-back tasks)
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(tasks-waits tasks)
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(make-hasheq)
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(tasks-cache tasks)
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#t))))
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(let ([t (car (tasks-active tasks))]
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[tasks (make-tasks (cdr (tasks-active tasks))
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(tasks-active-back tasks)
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(tasks-waits tasks)
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(tasks-multi-waits tasks)
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(tasks-cache tasks)
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(tasks-progress? tasks))])
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(t max-depth tasks))))
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;; Finds the symbolic representative of a token class
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(define-for-syntax (map-token toks tok)
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(car (token-identifier-mapping-get toks tok)))
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(define no-pos-val (make-position #f #f #f))
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(define-for-syntax no-pos
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(let ([npv ((syntax-local-certifier) #'no-pos-val)])
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(lambda (stx) npv)))
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(define-for-syntax at-tok-pos
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(lambda (sel expr)
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(lambda (stx)
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#`(let ([v #,expr]) (if v (#,sel v) no-pos-val)))))
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;; Builds a matcher for a particular alternative
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(define-for-syntax (build-match nts toks pat handle $ctx)
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(let loop ([pat pat]
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[pos 1])
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(if (null? pat)
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#`(success-k #,handle stream last-consumed-token depth max-depth tasks
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(lambda (success-k fail-k max-depth tasks)
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(fail-k max-depth tasks)))
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(let ([id (datum->syntax (car pat)
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(string->symbol (format "$~a" pos)))]
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[id-start-pos (datum->syntax (car pat)
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(string->symbol (format "$~a-start-pos" pos)))]
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[id-end-pos (datum->syntax (car pat)
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(string->symbol (format "$~a-end-pos" pos)))]
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[n-end-pos (and (null? (cdr pat))
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(datum->syntax (car pat) '$n-end-pos))])
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(cond
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[(bound-identifier-mapping-get nts (car pat) (lambda () #f))
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;; Match non-termimal
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#`(parse-and
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;; First part is simple? (If so, we don't have to parallelize the `and'.)
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#,(let ([l (bound-identifier-mapping-get nts (car pat) (lambda () #f))])
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(or (not l)
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(andmap values (caddr l))))
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#,(car pat)
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(let ([original-stream stream])
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(lambda (#,id stream last-consumed-token depth end success-k fail-k max-depth tasks)
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(let-syntax ([#,id-start-pos (at-tok-pos #'(if (eq? original-stream stream)
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tok-end
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tok-start)
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#'(if (eq? original-stream stream)
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last-consumed-token
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(and (pair? original-stream)
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(car original-stream))))]
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[#,id-end-pos (at-tok-pos #'tok-end #'last-consumed-token)]
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#,@(if n-end-pos
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#`([#,n-end-pos (at-tok-pos #'tok-end #'last-consumed-token)])
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null))
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#,(loop (cdr pat) (add1 pos)))))
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stream last-consumed-token depth
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#,(let ([cnt (apply +
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(map (lambda (item)
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(cond
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[(bound-identifier-mapping-get nts item (lambda () #f))
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=> (lambda (l) (car l))]
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[else 1]))
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(cdr pat)))])
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#`(- end #,cnt))
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success-k fail-k max-depth tasks)]
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[else
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;; Match token
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(let ([tok-id (map-token toks (car pat))])
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#`(if (and (pair? stream)
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(eq? '#,tok-id (tok-name (car stream))))
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(let* ([stream-a (car stream)]
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[#,id (tok-val stream-a)]
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[last-consumed-token (car stream)]
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[stream (cdr stream)]
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[depth (add1 depth)])
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(let ([max-depth (max max-depth depth)])
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(let-syntax ([#,id-start-pos (at-tok-pos #'tok-start #'stream-a)]
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[#,id-end-pos (at-tok-pos #'tok-end #'stream-a)]
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#,@(if n-end-pos
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#`([#,n-end-pos (at-tok-pos #'tok-end #'stream-a)])
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null))
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#,(loop (cdr pat) (add1 pos)))))
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(fail-k max-depth tasks)))])))))
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;; Starts parsing to match a non-terminal. There's a minor
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;; optimization that checks for known starting tokens. Otherwise,
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;; use the cache, block if someone else is already trying the match,
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;; and cache the result if it's computed.
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;; The cache maps nontermial+startingpos+iteration to a result, where
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;; the iteration is 0 for the first match attempt, 1 for the second,
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;; etc.
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(define (parse-nt/share key min-cnt init-tokens stream last-consumed-token depth end max-depth tasks success-k fail-k k)
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(if (and (positive? min-cnt)
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(pair? stream)
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(not (memq (tok-name (car stream)) init-tokens)))
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;; No such leading token; give up
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(fail-k max-depth tasks)
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;; Run pattern
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(let loop ([n 0]
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[success-k success-k]
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[fail-k fail-k]
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[max-depth max-depth]
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[tasks tasks]
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[k k])
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(let ([answer-key (gensym)]
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[table-key (vector key depth n)]
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[old-depth depth]
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[old-stream stream])
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#;(printf "Loop ~a\n" table-key)
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(cond
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[(hash-ref (tasks-cache tasks) table-key (lambda () #f))
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=> (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)))])))))
|
||||
|
||||
(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 `%start` and `%atok`
|
||||
;; 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.
|
||||
#`(grammar (%start [() null]
|
||||
[(%atok %start) (cons $1 $2)])
|
||||
(%atok [(tok) (make-tok 'tok-id 'tok $e pos ...)] ...)))
|
||||
#`(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") . *)) . *)) . *))
|
||||
.
|
||||
*))
|
||||
.
|
||||
*)))))
|
||||
(require br-parser-tools/cfg-parser)
|
||||
(provide cfg-parser)
|
||||
Loading…
Reference in New Issue