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