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Inlines `begin-with-disappeared-uses`, which means the big indentation

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change is in this commit instead of the previous one.
master
Jesse A. Tov 5 years ago committed by Matthew Butterick
parent c8851d31c5
commit 785af47262
1 changed files with 68 additions and 75 deletions
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143
br-parser-tools-lib/br-parser-tools/lex.rkt
Unescape Escape View File

@ -71,85 +71,78 @@
[lexeme-srcloc (make-rename-transformer #'lexeme-srcloc-p)])
action-stx)))))
(begin-for-syntax
; This macro only exists to keep the indentation below the same,
; in order to make the diff easier to read. So it probably makes
; sense to inline it after reading.
(define-syntax-rule (begin-with-disappeared-uses body0 body ...)
(with-disappeared-uses
(let () body0 body ...))))
(define-for-syntax (make-lexer-macro caller src-loc-style)
(λ (stx)
(syntax-case stx ()
[(_ . RE+ACTS)
(begin-with-disappeared-uses
(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 (case src-loc-style
[(lexer-src-pos) #'(return-without-pos eof)]
[(lexer-srcloc) #'(return-without-srcloc eof)]
[else #'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) (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/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)))))))])))
(with-disappeared-uses
(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 (case src-loc-style
[(lexer-src-pos) #'(return-without-pos eof)]
[(lexer-srcloc) #'(return-without-srcloc eof)]
[else #'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) (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/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))))))))])))
(define-syntax lexer (make-lexer-macro 'lexer #f))
(define-syntax lexer-src-pos (make-lexer-macro 'lexer-src-pos 'lexer-src-pos))

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