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