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irregex-core.scm
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irregex-core.scm
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;;;; irregex.scm -- IrRegular Expressions
;;
;; Copyright (c) 2005-2020 Alex Shinn. All rights reserved.
;; BSD-style license: http://synthcode.com/license.txt
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; At this moment there was a loud ring at the bell, and I could
;; hear Mrs. Hudson, our landlady, raising her voice in a wail of
;; expostulation and dismay.
;;
;; "By heaven, Holmes," I said, half rising, "I believe that
;; they are really after us."
;;
;; "No, it's not quite so bad as that. It is the unofficial
;; force, -- the Baker Street irregulars."
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;;; Notes
;;
;; This code should not require any porting - it should work out of
;; the box in any R[457]RS Scheme implementation. Slight modifications
;; are needed for R6RS (a separate R6RS-compatible version is included
;; in the distribution as irregex-r6rs.scm).
;;
;; The goal of portability makes this code a little clumsy and
;; inefficient. Future versions will include both cleanup and
;; performance tuning, but you can only go so far while staying
;; portable. AND-LET*, SRFI-9 records and custom macros would've been
;; nice.
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;;; History
;; 0.9.8: 2020/07/13 - fix irregex-replace/all with look-behind patterns
;; 0.9.7: 2019/12/31 - more intuitive handling of empty matches in -fold,
;; -replace and -split
;; 0.9.6: 2016/12/05 - fixed exponential memory use of + in compilation
;; of backtracking matcher (CVE-2016-9954).
;; 0.9.5: 2016/09/10 - fixed a bug in irregex-fold handling of bow
;; 0.9.4: 2015/12/14 - performance improvement for {n,m} matches
;; 0.9.3: 2014/07/01 - R7RS library
;; 0.9.2: 2012/11/29 - fixed a bug in -fold on conditional bos patterns
;; 0.9.1: 2012/11/27 - various accumulated bugfixes
;; 0.9.0: 2012/06/03 - Using tags for match extraction from Peter Bex.
;; 0.8.3: 2011/12/18 - various accumulated bugfixes
;; 0.8.2: 2010/08/28 - (...)? submatch extraction fix and alternate
;; named submatches from Peter Bex
;; Added irregex-split, irregex-extract,
;; irregex-match-names and irregex-match-valid-index?
;; to Chicken and Guile module export lists and made
;; the latter accept named submatches. The procedures
;; irregex-match-{start,end}-{index,chunk} now also
;; accept named submatches, with the index argument
;; made optional. Improved argument type checks.
;; Disallow negative submatch index.
;; Improve performance of backtracking matcher.
;; Refactor charset handling into a consistent API
;; 0.8.1: 2010/03/09 - backtracking irregex-match fix and other small fixes
;; 0.8.0: 2010/01/20 - optimizing DFA compilation, adding SRE escapes
;; inside PCREs, adding utility SREs
;; 0.7.5: 2009/08/31 - adding irregex-extract and irregex-split
;; *-fold copies match data (use *-fold/fast for speed)
;; irregex-opt now returns an SRE
;; 0.7.4: 2009/05/14 - empty alternates (or) and empty csets always fail,
;; bugfix in default finalizer for irregex-fold/chunked
;; 0.7.3: 2009/04/14 - adding irregex-fold/chunked, minor doc fixes
;; 0.7.2: 2009/02/11 - some bugfixes, much improved documentation
;; 0.7.1: 2008/10/30 - several bugfixes (thanks to Derick Eddington)
;; 0.7.0: 2008/10/20 - support abstract chunked strings
;; 0.6.2: 2008/07/26 - minor bugfixes, allow global disabling of utf8 mode,
;; friendlier error messages in parsing, \Q..\E support
;; 0.6.1: 2008/07/21 - added utf8 mode, more utils, bugfixes
;; 0.6: 2008/05/01 - most of PCRE supported
;; 0.5: 2008/04/24 - fully portable R4RS, many PCRE features implemented
;; 0.4: 2008/04/17 - rewriting NFA to use efficient closure compilation,
;; normal strings only, but all of the spencer tests pass
;; 0.3: 2008/03/10 - adding DFA converter (normal strings only)
;; 0.2: 2005/09/27 - adding irregex-opt (like elisp's regexp-opt) utility
;; 0.1: 2005/08/18 - simple NFA interpreter over abstract chunked strings
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;;; Data Structures
(define (vector-copy v)
(let ((v2 (make-vector (vector-length v))))
(vector-copy! v v2)
v2))
(cond-expand
(chicken-bootstrap
(begin
;; make-irregex defined elsewhere
(define (irregex? x)
(##sys#structure? x 'regexp))
(define (irregex-dfa x)
(##sys#check-structure x 'regexp 'irregex-dfa)
(##sys#slot x 1))
(define (irregex-dfa/search x)
(##sys#check-structure x 'regexp 'irregex-dfa/search)
(##sys#slot x 2))
(define (irregex-nfa x)
(##sys#check-structure x 'regexp 'irregex-nfa)
(##sys#slot x 3))
(define (irregex-flags x)
(##sys#check-structure x 'regexp 'irregex-flags)
(##sys#slot x 4))
(define (irregex-num-submatches x)
(##sys#check-structure x 'regexp 'irregex-num-submatches)
(##sys#slot x 5))
(define (irregex-lengths x)
(##sys#check-structure x 'regexp 'irregex-lengths)
(##sys#slot x 6))
(define (irregex-names x)
(##sys#check-structure x 'regexp 'irregex-names)
(##sys#slot x 7))
;; make-irregex-match defined elsewhere
(define (irregex-new-matches irx)
(make-irregex-match (irregex-num-submatches irx) (irregex-names irx)))
(define (irregex-reset-matches! m)
(let ((v (##sys#slot m 1)))
(vector-fill! v #f)
m))
(define (irregex-copy-matches m)
(and (##sys#structure? m 'regexp-match)
(##sys#make-structure
'regexp-match
(vector-copy (##sys#slot m 1))
(##sys#slot m 2)
(##sys#slot m 3)
(##sys#slot m 4))))
(define (irregex-match-data? obj)
(##sys#structure? obj 'regexp-match))
(define (irregex-match-num-submatches m)
(##sys#check-structure m 'regexp-match 'irregex-match-num-submatches)
(- (fx/ (##sys#size (##sys#slot m 1)) 4) 2))
(define (irregex-match-chunker m)
(##sys#slot m 3))
(define (irregex-match-names m)
(##sys#check-structure m 'regexp-match 'irregex-match-names)
(##sys#slot m 2))
(define (irregex-match-chunker-set! m str)
(##sys#setslot m 3 str))
(define-inline (%irregex-match-start-chunk m n)
(##sys#slot (##sys#slot m 1) (* n 4)))
(define-inline (%irregex-match-start-index m n)
(##sys#slot (##sys#slot m 1) (+ 1 (* n 4))))
(define-inline (%irregex-match-end-chunk m n)
(##sys#slot (##sys#slot m 1) (+ 2 (* n 4))))
(define (%irregex-match-end-index m n)
(##sys#slot (##sys#slot m 1) (+ 3 (* n 4))))
(define (%irregex-match-fail m) (##sys#slot m 4))
(define (%irregex-match-fail-set! m x) (##sys#setslot m 4 x))
(set-record-printer! 'regexp-match
(lambda (m out)
(let ((n (irregex-match-num-submatches m)))
(display "#<regexp-match (" out)
(display n out)
(display " submatch" out)
(when (or (eq? n 0) (fx> n 1)) (display "es" out))
(display ")>" out))))
(define-inline (irregex-match-valid-numeric-index? m n)
(let ((v (##sys#slot m 1)))
(and (>= n 0) (< (* n 4) (- (##sys#size v) 4)))))
(define-inline (irregex-match-matched-numeric-index? m n)
(let ((v (##sys#slot m 1)))
(and (##sys#slot v (+ 1 (* n 4)))
#t)))))
(else
(begin
(define irregex-tag '*irregex-tag*)
(define (make-irregex dfa dfa/search nfa flags submatches lengths names)
(vector irregex-tag dfa dfa/search nfa flags submatches lengths names))
(define (irregex? obj)
(and (vector? obj)
(= 8 (vector-length obj))
(eq? irregex-tag (vector-ref obj 0))))
(define (irregex-dfa x) (vector-ref x 1))
(define (irregex-dfa/search x) (vector-ref x 2))
(define (irregex-nfa x) (vector-ref x 3))
(define (irregex-flags x) (vector-ref x 4))
(define (irregex-num-submatches x) (vector-ref x 5))
(define (irregex-lengths x) (vector-ref x 6))
(define (irregex-names x) (vector-ref x 7))
(define (irregex-new-matches irx)
(make-irregex-match (irregex-num-submatches irx) (irregex-names irx)))
(define (irregex-reset-matches! m)
(do ((i (- (vector-length m) 1) (- i 1)))
((<= i 3) m)
(vector-set! m i #f)))
(define (irregex-copy-matches m)
(and (vector? m) (vector-copy m)))
(define irregex-match-tag '*irregex-match-tag*)
(define (irregex-match-data? obj)
(and (vector? obj)
(>= (vector-length obj) 11)
(eq? irregex-match-tag (vector-ref obj 0))))
(define (make-irregex-match count names)
(let ((res (make-vector (+ (* 4 (+ 2 count)) 3) #f)))
(vector-set! res 0 irregex-match-tag)
(vector-set! res 2 names)
res))
(define (irregex-match-num-submatches m)
(- (quotient (- (vector-length m) 3) 4) 2))
(define (irregex-match-chunker m)
(vector-ref m 1))
(define (irregex-match-names m)
(vector-ref m 2))
(define (irregex-match-chunker-set! m str)
(vector-set! m 1 str))
(define (%irregex-match-start-chunk m n) (vector-ref m (+ 3 (* n 4))))
(define (%irregex-match-start-index m n) (vector-ref m (+ 4 (* n 4))))
(define (%irregex-match-end-chunk m n) (vector-ref m (+ 5 (* n 4))))
(define (%irregex-match-end-index m n) (vector-ref m (+ 6 (* n 4))))
(define (%irregex-match-fail m) (vector-ref m (- (vector-length m) 1)))
(define (%irregex-match-fail-set! m x) (vector-set! m (- (vector-length m) 1) x))
(define (irregex-match-valid-numeric-index? m n)
(and (>= n 0) (< (+ 3 (* n 4)) (- (vector-length m) 4))))
(define (irregex-match-matched-numeric-index? m n)
(and (vector-ref m (+ 4 (* n 4)))
#t)))))
(define (irregex-match-valid-named-index? m n)
(and (assq n (irregex-match-names m))
#t))
;; public interface with error checking
(define (irregex-match-start-chunk m . opt)
(let ((n (irregex-match-numeric-index 'irregex-match-start-chunk m opt)))
(and n (%irregex-match-start-chunk m n))))
(define (irregex-match-start-index m . opt)
(let ((n (irregex-match-numeric-index 'irregex-match-start-index m opt)))
(and n (%irregex-match-start-index m n))))
(define (irregex-match-end-chunk m . opt)
(let ((n (irregex-match-numeric-index 'irregex-match-end-chunk m opt)))
(and n (%irregex-match-end-chunk m n))))
(define (irregex-match-end-index m . opt)
(let ((n (irregex-match-numeric-index 'irregex-match-end-index m opt)))
(and n (%irregex-match-end-index m n))))
(define (irregex-match-start-chunk-set! m n start)
(vector-set! m (+ 3 (* n 4)) start))
(define (irregex-match-start-index-set! m n start)
(vector-set! m (+ 4 (* n 4)) start))
(define (irregex-match-end-chunk-set! m n end)
(vector-set! m (+ 5 (* n 4)) end))
(define (irregex-match-end-index-set! m n end)
(vector-set! m (+ 6 (* n 4)) end))
;; Tags use indices that are aligned to start/end positions just like the
;; match vectors. ie, a tag 0 is a start tag, 1 is its corresponding end tag.
;; They start at 0, which requires us to map them to submatch index 1.
;; Sorry for the horrible name ;)
(define (irregex-match-chunk&index-from-tag-set! m t chunk index)
(vector-set! m (+ 7 (* t 2)) chunk)
(vector-set! m (+ 8 (* t 2)) index))
;; Helper procedure to convert any type of index from a rest args list
;; to a numeric index. Named submatches are converted to their corresponding
;; numeric index, and numeric submatches are checked for validity.
;; An error is raised for invalid numeric or named indices, #f is returned
;; for defined but nonmatching indices.
(define (irregex-match-numeric-index location m opt)
(cond
((not (irregex-match-data? m))
(error location "not match data" m))
((not (pair? opt)) 0)
((pair? (cdr opt))
(apply error location "too many arguments" m opt))
(else
(let ((n (car opt)))
(if (number? n)
(if (and (integer? n) (exact? n))
(if (irregex-match-valid-numeric-index? m n)
(and (irregex-match-matched-numeric-index? m n) n)
(error location "not a valid index" m n))
(error location "not an exact integer" n))
(let lp ((ls (irregex-match-names m))
(unknown? #t))
(cond
((null? ls)
(and unknown?
(error location "unknown match name" n)))
((eq? n (caar ls))
(if (%irregex-match-start-chunk m (cdar ls))
(cdar ls)
(lp (cdr ls) #f)))
(else (lp (cdr ls) unknown?)))))))))
(define (irregex-match-valid-index? m n)
(if (not (irregex-match-data? m))
(error 'irregex-match-valid-index? "not match data" m))
(if (integer? n)
(if (not (exact? n))
(error 'irregex-match-valid-index? "not an exact integer" n)
(irregex-match-valid-numeric-index? m n))
(irregex-match-valid-named-index? m n)))
(define (irregex-match-substring m . opt)
(let* ((n (irregex-match-numeric-index 'irregex-match-substring m opt))
(cnk (irregex-match-chunker m)))
(and n
((chunker-get-substring cnk)
(%irregex-match-start-chunk m n)
(%irregex-match-start-index m n)
(%irregex-match-end-chunk m n)
(%irregex-match-end-index m n)))))
(define (irregex-match-subchunk m . opt)
(let* ((n (irregex-match-numeric-index 'irregex-match-subchunk m opt))
(cnk (irregex-match-chunker m))
(get-subchunk (chunker-get-subchunk cnk)))
(if (not get-subchunk)
(error "this chunk type does not support match subchunks" m n)
(and n (get-subchunk
(%irregex-match-start-chunk m n)
(%irregex-match-start-index m n)
(%irregex-match-end-chunk m n)
(%irregex-match-end-index m n))))))
;; chunkers tell us how to navigate through chained chunks of strings
(define (make-irregex-chunker get-next get-str . o)
(let* ((get-start (or (and (pair? o) (car o)) (lambda (cnk) 0)))
(o (if (pair? o) (cdr o) o))
(get-end (or (and (pair? o) (car o))
(lambda (cnk) (string-length (get-str cnk)))))
(o (if (pair? o) (cdr o) o))
(get-substr
(or (and (pair? o) (car o))
(lambda (cnk1 start cnk2 end)
(if (eq? cnk1 cnk2)
(substring (get-str cnk1) start end)
(let loop ((cnk (get-next cnk1))
(res (list (substring (get-str cnk1)
start
(get-end cnk1)))))
(if (eq? cnk cnk2)
(string-cat-reverse
(cons (substring (get-str cnk)
(get-start cnk)
end)
res))
(loop (get-next cnk)
(cons (substring (get-str cnk)
(get-start cnk)
(get-end cnk))
res))))))))
(o (if (pair? o) (cdr o) o))
(get-subchunk (and (pair? o) (car o))))
(if (not (and (procedure? get-next) (procedure? get-str)
(procedure? get-start) (procedure? get-substr)))
(error 'make-irregex-chunker "expected a procdure"))
(vector get-next get-str get-start get-end get-substr get-subchunk)))
(define (chunker-get-next cnk) (vector-ref cnk 0))
(define (chunker-get-str cnk) (vector-ref cnk 1))
(define (chunker-get-start cnk) (vector-ref cnk 2))
(define (chunker-get-end cnk) (vector-ref cnk 3))
(define (chunker-get-substring cnk) (vector-ref cnk 4))
(define (chunker-get-subchunk cnk) (vector-ref cnk 5))
(define (chunker-prev-chunk cnk start end)
(if (eq? start end)
#f
(let ((get-next (chunker-get-next cnk)))
(let lp ((start start))
(let ((next (get-next start)))
(if (eq? next end)
start
(and next (lp next))))))))
(define (chunker-prev-char cnk start end)
(let ((prev (chunker-prev-chunk cnk start end)))
(and prev
(string-ref ((chunker-get-str cnk) prev)
(- ((chunker-get-end cnk) prev) 1)))))
(define (chunker-next-char cnk src)
(let ((next ((chunker-get-next cnk) src)))
(and next
(string-ref ((chunker-get-str cnk) next)
((chunker-get-start cnk) next)))))
(define (chunk-before? cnk a b)
(and (not (eq? a b))
(let ((next ((chunker-get-next cnk) a)))
(and next
(if (eq? next b)
#t
(chunk-before? cnk next b))))))
;; For look-behind searches, wrap an existing chunker such that it
;; returns the same results but ends at a given point.
(define (wrap-end-chunker cnk src i)
(make-irregex-chunker
(lambda (x) (and (not (eq? x src)) ((chunker-get-next cnk) x)))
(chunker-get-str cnk)
(chunker-get-start cnk)
(lambda (x)
;; TODO: this is a hack workaround for the fact that we don't
;; have either a notion of chunk equivalence or chunk truncation,
;; until which time (neg-)look-behind in a fold won't work on
;; non-basic chunks.
(if (or (eq? x src)
(and (not ((chunker-get-next cnk) x))
(not ((chunker-get-next cnk) src))))
i
((chunker-get-end cnk) x)))
(chunker-get-substring cnk)
(chunker-get-subchunk cnk)))
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;;; String Utilities
;; Unicode version (skip surrogates)
(define *all-chars*
`(/ ,(integer->char 0) ,(integer->char #xD7FF)
,(integer->char #xE000) ,(integer->char #x10FFFF)))
;; ASCII version, offset to not assume 0-255
;; (define *all-chars* `(/ ,(integer->char (- (char->integer #\space) 32)) ,(integer->char (+ (char->integer #\space) 223))))
;; set to #f to ignore even an explicit request for utf8 handling
(define *allow-utf8-mode?* #t)
;; (define *named-char-properties* '())
(define (string-scan-char str c . o)
(let ((end (string-length str)))
(let scan ((i (if (pair? o) (car o) 0)))
(cond ((= i end) #f)
((eqv? c (string-ref str i)) i)
(else (scan (+ i 1)))))))
(define (string-scan-char-escape str c . o)
(let ((end (string-length str)))
(let scan ((i (if (pair? o) (car o) 0)))
(cond ((= i end) #f)
((eqv? c (string-ref str i)) i)
((eqv? c #\\) (scan (+ i 2)))
(else (scan (+ i 1)))))))
(define (string-scan-pred str pred . o)
(let ((end (string-length str)))
(let scan ((i (if (pair? o) (car o) 0)))
(cond ((= i end) #f)
((pred (string-ref str i)) i)
(else (scan (+ i 1)))))))
(define (string-split-char str c)
(let ((end (string-length str)))
(let lp ((i 0) (from 0) (res '()))
(define (collect) (cons (substring str from i) res))
(cond ((>= i end) (reverse (collect)))
((eqv? c (string-ref str i)) (lp (+ i 1) (+ i 1) (collect)))
(else (lp (+ i 1) from res))))))
(define (char-alphanumeric? c)
(or (char-alphabetic? c) (char-numeric? c)))
(define (%substring=? a b start1 start2 len)
(let lp ((i 0))
(cond ((>= i len)
#t)
((char=? (string-ref a (+ start1 i)) (string-ref b (+ start2 i)))
(lp (+ i 1)))
(else
#f))))
;; SRFI-13 extracts
(define (%%string-copy! to tstart from fstart fend)
(do ((i fstart (+ i 1))
(j tstart (+ j 1)))
((>= i fend))
(string-set! to j (string-ref from i))))
(define (string-cat-reverse string-list)
(string-cat-reverse/aux
(fold (lambda (s a) (+ (string-length s) a)) 0 string-list)
string-list))
(define (string-cat-reverse/aux len string-list)
(let ((res (make-string len)))
(let lp ((i len) (ls string-list))
(if (pair? ls)
(let* ((s (car ls))
(slen (string-length s))
(i (- i slen)))
(%%string-copy! res i s 0 slen)
(lp i (cdr ls)))))
res))
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;;; List Utilities
;; like the one-arg IOTA case
(define (zero-to n)
(if (<= n 0)
'()
(let lp ((i (- n 1)) (res '()))
(if (zero? i) (cons 0 res) (lp (- i 1) (cons i res))))))
;; SRFI-1 extracts (simplified 1-ary versions)
(define (find pred ls)
(let lp ((ls ls))
(cond ((null? ls) #f)
((pred (car ls)) (car ls))
(else (lp (cdr ls))))))
(define (find-tail pred ls)
(let lp ((ls ls))
(cond ((null? ls) #f)
((pred (car ls)) ls)
(else (lp (cdr ls))))))
(define (last ls)
(if (not (pair? ls))
(error "can't take last of empty list")
(let lp ((ls ls))
(if (pair? (cdr ls))
(lp (cdr ls))
(car ls)))))
(define (any pred ls)
(and (pair? ls)
(let lp ((head (car ls)) (tail (cdr ls)))
(if (null? tail)
(pred head)
(or (pred head) (lp (car tail) (cdr tail)))))))
(define (every pred ls)
(or (null? ls)
(let lp ((head (car ls)) (tail (cdr ls)))
(if (null? tail)
(pred head)
(and (pred head) (lp (car tail) (cdr tail)))))))
(define (fold kons knil ls)
(let lp ((ls ls) (res knil))
(if (null? ls)
res
(lp (cdr ls) (kons (car ls) res)))))
(define (filter pred ls)
(let lp ((ls ls) (res '()))
(if (null? ls)
(reverse res)
(lp (cdr ls) (if (pred (car ls)) (cons (car ls) res) res)))))
(define (remove pred ls)
(let lp ((ls ls) (res '()))
(if (null? ls)
(reverse res)
(lp (cdr ls) (if (pred (car ls)) res (cons (car ls) res))))))
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;;; Flags
(define (bit-shr n i)
(quotient n (expt 2 i)))
(define (bit-shl n i)
(* n (expt 2 i)))
(define (bit-not n) (- #xFFFF n))
(define (bit-ior a b)
(cond
((zero? a) b)
((zero? b) a)
(else
(+ (if (or (odd? a) (odd? b)) 1 0)
(* 2 (bit-ior (quotient a 2) (quotient b 2)))))))
(define (bit-and a b)
(cond
((zero? a) 0)
((zero? b) 0)
(else
(+ (if (and (odd? a) (odd? b)) 1 0)
(* 2 (bit-and (quotient a 2) (quotient b 2)))))))
(define (integer-log n)
(define (b8 n r)
(if (>= n (bit-shl 1 8)) (b4 (bit-shr n 8) (+ r 8)) (b4 n r)))
(define (b4 n r)
(if (>= n (bit-shl 1 4)) (b2 (bit-shr n 4) (+ r 4)) (b2 n r)))
(define (b2 n r)
(if (>= n (bit-shl 1 2)) (b1 (bit-shr n 2) (+ r 2)) (b1 n r)))
(define (b1 n r) (if (>= n (bit-shl 1 1)) (+ r 1) r))
(if (>= n (bit-shl 1 16)) (b8 (bit-shr n 16) 16) (b8 n 0)))
(define (flag-set? flags i)
(= i (bit-and flags i)))
(define (flag-join a b)
(if b (bit-ior a b) a))
(define (flag-clear a b)
(bit-and a (bit-not b)))
(define ~none 0)
(define ~searcher? 1)
(define ~consumer? 2)
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;;; Parsing Embedded SREs in PCRE Strings
;; (define (with-read-from-string str i proc)
;; (define (port-size in)
;; (let lp ((i 0)) (if (eof-object? (read-char in)) i (lp (+ i 1)))))
;; (let* ((len (string-length str))
;; (tail-len (- len i))
;; (in (open-input-string (substring str i len)))
;; (sre (read in))
;; (unused-len (port-size in)))
;; (close-input-port in)
;; (proc sre (- tail-len unused-len))))
(define close-token (list 'close))
(define dot-token (string->symbol "."))
(define (with-read-from-string str i proc)
(define end (string-length str))
(define (read i k)
(cond
((>= i end) (error "unterminated embedded SRE" str))
(else
(case (string-ref str i)
((#\()
(let lp ((i (+ i 1)) (ls '()))
(read
i
(lambda (x j)
(cond
((eq? x close-token)
(k (reverse ls) j))
((eq? x dot-token)
(if (null? ls)
(error "bad dotted form" str)
(read j (lambda (y j2)
(read j2 (lambda (z j3)
(if (not (eq? z close-token))
(error "bad dotted form" str)
(k (append (reverse (cdr ls))
(cons (car ls) y))
j3))))))))
(else
(lp j (cons x ls))))))))
((#\))
(k close-token (+ i 1)))
((#\;)
(let skip ((i (+ i 1)))
(if (or (>= i end) (eqv? #\newline (string-ref str i)))
(read (+ i 1) k)
(skip (+ i 1)))))
((#\' #\`)
(read (+ i 1)
(lambda (sexp j)
(let ((q (if (eqv? #\' (string-ref str i)) 'quote 'quasiquote)))
(k (list q sexp) j)))))
((#\,)
(let* ((at? (and (< (+ i 1) end) (eqv? #\@ (string-ref str (+ i 1)))))
(u (if at? 'uquote-splicing 'unquote))
(j (if at? (+ i 2) (+ i 1))))
(read j (lambda (sexp j) (k (list u sexp) j)))))
((#\")
(let scan ((from (+ i 1)) (i (+ i 1)) (res '()))
(define (collect)
(if (= from i) res (cons (substring str from i) res)))
(if (>= i end)
(error "unterminated string in embedded SRE" str)
(case (string-ref str i)
((#\") (k (string-cat-reverse (collect)) (+ i 1)))
((#\\) (scan (+ i 1) (+ i 2) (collect)))
(else (scan from (+ i 1) res))))))
((#\#)
(case (string-ref str (+ i 1))
((#\;)
(read (+ i 2) (lambda (sexp j) (read j k))))
((#\\)
(read (+ i 2)
(lambda (sexp j)
(k (case sexp
((space) #\space)
((newline) #\newline)
(else (let ((s (if (number? sexp)
(number->string sexp)
(symbol->string sexp))))
(string-ref s 0))))
j))))
((#\t #\f)
(k (eqv? #\t (string-ref str (+ i 1))) (+ i 2)))
(else
(error "bad # syntax in simplified SRE" i))))
(else
(cond
((char-whitespace? (string-ref str i))
(read (+ i 1) k))
(else ;; symbol/number
(let scan ((j (+ i 1)))
(cond
((or (>= j end)
(let ((c (string-ref str j)))
(or (char-whitespace? c)
(memv c '(#\; #\( #\) #\" #\# #\\)))))
(let ((str2 (substring str i j)))
(k (or (string->number str2) (string->symbol str2)) j)))
(else (scan (+ j 1))))))))))))
(read i (lambda (res j)
(if (eq? res 'close-token)
(error "unexpected ')' in SRE" str j)
(proc res j)))))
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;;; Parsing PCRE Strings
(define ~save? 1)
(define ~case-insensitive? 2)
(define ~multi-line? 4)
(define ~single-line? 8)
(define ~ignore-space? 16)
(define ~utf8? 32)
(define (symbol-list->flags ls)
(let lp ((ls ls) (res ~none))
(if (not (pair? ls))
res
(lp (cdr ls)
(flag-join
res
(case (car ls)
((i ci case-insensitive) ~case-insensitive?)
((m multi-line) ~multi-line?)
((s single-line) ~single-line?)
((x ignore-space) ~ignore-space?)
((u utf8) (if *allow-utf8-mode?* ~utf8? ~none))
(else #f)))))))
(define (maybe-string->sre obj)
(if (string? obj) (string->sre obj) obj))
(define (string->sre str . o)
(if (not (string? str)) (error 'string->sre "expected a string" str))
(let ((end (string-length str))
(flags (symbol-list->flags o)))
(let lp ((i 0) (from 0) (flags flags) (res '()) (st '()))
;; handle case sensitivity at the literal char/string level
(define (cased-char ch)
(if (and (flag-set? flags ~case-insensitive?)
(char-alphabetic? ch))
`(or ,ch ,(char-altcase ch))
ch))
(define (cased-string str)
(if (flag-set? flags ~case-insensitive?)
(sre-sequence (map cased-char (string->list str)))
str))
;; accumulate the substring from..i as literal text
(define (collect)
(if (= i from) res (cons (cased-string (substring str from i)) res)))
;; like collect but breaks off the last single character when
;; collecting literal data, as the argument to ?/*/+ etc.
(define (collect/single)
(let* ((utf8? (flag-set? flags ~utf8?))
(j (if (and utf8? (> i 1))
(utf8-backup-to-initial-char str (- i 1))
(- i 1))))
(cond
((< j from)
res)
(else
(let ((c (cased-char (if utf8?
(utf8-string-ref str j (- i j))
(string-ref str j)))))
(cond
((= j from)
(cons c res))
(else
(cons c
(cons (cased-string (substring str from j))
res)))))))))
;; collects for use as a result, reversing and grouping OR
;; terms, and some ugly tweaking of `function-like' groups and
;; conditionals
(define (collect/terms)
(let* ((ls (collect))
(func
(and (pair? ls)
(memq (last ls)
'(atomic if look-ahead neg-look-ahead
look-behind neg-look-behind
=> submatch-named
w/utf8 w/noutf8))))
(prefix (if (and func (memq (car func) '(=> submatch-named)))
(list 'submatch-named (cadr (reverse ls)))
(and func (list (car func)))))
(ls (if func
(if (memq (car func) '(=> submatch-named))
(reverse (cddr (reverse ls)))
(reverse (cdr (reverse ls))))
ls)))
(let lp ((ls ls) (term '()) (res '()))
(define (shift)
(cons (sre-sequence term) res))
(cond
((null? ls)
(let* ((res (sre-alternate (shift)))
(res (if (flag-set? flags ~save?)
(list 'submatch res)
res)))
(if prefix
(if (eq? 'if (car prefix))
(cond
((not (pair? res))
'epsilon)
((memq (car res)
'(look-ahead neg-look-ahead
look-behind neg-look-behind))
res)
((eq? 'seq (car res))
`(if ,(cadr res)
,(sre-sequence (cddr res))))
(else
`(if ,(cadadr res)
,(sre-sequence (cddadr res))
,(sre-alternate (cddr res)))))
`(,@prefix ,res))
res)))
((eq? 'or (car ls)) (lp (cdr ls) '() (shift)))
(else (lp (cdr ls) (cons (car ls) term) res))))))
(define (save)
(cons (cons flags (collect)) st))
;; main parsing
(if (>= i end)
(if (pair? st)
(error "unterminated parenthesis in regexp" str)
(collect/terms))
(let ((c (string-ref str i)))
(case c
((#\.)
(lp (+ i 1) (+ i 1) flags
(cons (if (flag-set? flags ~single-line?) 'any 'nonl)
(collect))
st))
((#\?)
(let ((res (collect/single)))
(if (null? res)
(error "? can't follow empty pattern" str res)
(let ((x (car res)))
(lp (+ i 1)
(+ i 1)
flags
(cons
(if (pair? x)
(case (car x)
((*) `(*? ,@(cdr x)))
((+) `(**? 1 #f ,@(cdr x)))
((?) `(?? ,@(cdr x)))
((**) `(**? ,@(cdr x)))
((=) `(**? ,(cadr x) ,@(cdr x)))
((>=) `(**? ,(cadr x) #f ,@(cddr x)))
(else `(? ,x)))
`(? ,x))
(cdr res))
st)))))
((#\+ #\*)
(let* ((res (collect/single))
(x (if (pair? res) (car res) 'epsilon))
(op (string->symbol (string c))))
(cond
((sre-repeater? x)
(error "duplicate repetition (e.g. **) in pattern" str res))
((sre-empty? x)
(error "can't repeat empty pattern (e.g. ()*)" str res))
(else
(lp (+ i 1) (+ i 1) flags
(cons (list op x) (cdr res))
st)))))
((#\()
(cond
((>= (+ i 1) end)
(error "unterminated parenthesis in regexp" str))
((not (memv (string-ref str (+ i 1)) '(#\? #\*))) ; normal case
(lp (+ i 1) (+ i 1) (flag-join flags ~save?) '() (save)))
((>= (+ i 2) end)
(error "unterminated parenthesis in regexp" str))
((eqv? (string-ref str (+ i 1)) #\*)
(if (eqv? #\' (string-ref str (+ i 2)))
(with-read-from-string str (+ i 3)
(lambda (sre j)
(if (or (>= j end) (not (eqv? #\) (string-ref str j))))
(error "unterminated (*'...) SRE escape" str)
(lp (+ j 1) (+ j 1) flags (cons sre (collect)) st))))
(error "bad regexp syntax: (*FOO) not supported" str)))
(else ;; (?...) case
(case (string-ref str (+ i 2))
((#\#)
(let ((j (string-scan-char str #\) (+ i 3))))
(lp (+ j i) (+ j 1) flags (collect) st)))
((#\:)
(lp (+ i 3) (+ i 3) (flag-clear flags ~save?) '() (save)))
((#\=)
(lp (+ i 3) (+ i 3) (flag-clear flags ~save?)
'(look-ahead) (save)))
((#\!)
(lp (+ i 3) (+ i 3) (flag-clear flags ~save?)
'(neg-look-ahead) (save)))
((#\<)
(cond
((>= (+ i 3) end)
(error "unterminated parenthesis in regexp" str))
(else
(case (string-ref str (+ i 3))
((#\=)
(lp (+ i 4) (+ i 4) (flag-clear flags ~save?)
'(look-behind) (save)))
((#\!)
(lp (+ i 4) (+ i 4) (flag-clear flags ~save?)
'(neg-look-behind) (save)))
(else
(let ((j (and (char-alphabetic?
(string-ref str (+ i 3)))
(string-scan-char str #\> (+ i 4)))))
(if j
(lp (+ j 1) (+ j 1) (flag-clear flags ~save?)
`(,(string->symbol (substring str (+ i 3) j))
submatch-named)
(save))
(error "invalid (?< sequence" str))))))))
((#\>)
(lp (+ i 3) (+ i 3) (flag-clear flags ~save?)
'(atomic) (save)))
;;((#\' #\P) ; named subpatterns
;; )
;;((#\R) ; recursion
;; )
((#\()
(cond
((>= (+ i 3) end)
(error "unterminated parenthesis in regexp" str))
((char-numeric? (string-ref str (+ i 3)))
(let* ((j (string-scan-char str #\) (+ i 3)))
(n (string->number (substring str (+ i 3) j))))
(if (not n)
(error "invalid conditional reference" str)
(lp (+ j 1) (+ j 1) (flag-clear flags ~save?)
`(,n if) (save)))))
((char-alphabetic? (string-ref str (+ i 3)))
(let* ((j (string-scan-char str #\) (+ i 3)))
(s (string->symbol (substring str (+ i 3) j))))
(lp (+ j 1) (+ j 1) (flag-clear flags ~save?)
`(,s if) (save))))
(else
(lp (+ i 2) (+ i 2) (flag-clear flags ~save?)
'(if) (save)))))
((#\{)
(error "unsupported Perl-style cluster" str))
(else
(let ((old-flags flags))
(let lp2 ((j (+ i 2)) (flags flags) (invert? #f))
(define (join x)
((if invert? flag-clear flag-join) flags x))
(define (new-res res)
(let ((before (flag-set? old-flags ~utf8?))
(after (flag-set? flags ~utf8?)))
(if (eq? before after)
res
(cons (if after 'w/utf8 'w/noutf8) res))))
(cond
((>= j end)
(error "incomplete cluster" str i))
(else
(case (string-ref str j)
((#\i)
(lp2 (+ j 1) (join ~case-insensitive?) invert?))
((#\m)
(lp2 (+ j 1) (join ~multi-line?) invert?))
((#\x)
(lp2 (+ j 1) (join ~ignore-space?) invert?))
((#\u)
(if *allow-utf8-mode?*
(lp2 (+ j 1) (join ~utf8?) invert?)
(lp2 (+ j 1) flags invert?)))
((#\-)
(lp2 (+ j 1) flags (not invert?)))
((#\))
(lp (+ j 1) (+ j 1) flags (new-res (collect))
st))
((#\:)
(lp (+ j 1) (+ j 1) flags (new-res '())
(cons (cons old-flags (collect)) st)))
(else
(error "unknown regex cluster modifier" str)
)))))))))))
((#\))
(if (null? st)
(error "too many )'s in regexp" str)
(lp (+ i 1)