795 lines
32 KiB
Scheme
795 lines
32 KiB
Scheme
;pregexp.scm
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;Portable regular expressions for Scheme
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;Dorai Sitaram
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;http://www.ccs.neu.edu/~dorai
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;dorai AT ccs DOT neu DOT edu
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;Oct 2, 1999
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;;; ported to ikarus by Abdulaziz Ghuloum on Dec 19, 2007.
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;;; also added special cases for when the first argument to
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;;; any of these procedures is a known string at macro
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;;; expansion time.
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(library (pregexp)
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(export pregexp pregexp-match-positions pregexp-match
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pregexp-split pregexp-replace pregexp-replace*)
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(import (ikarus))
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(define *pregexp-version* 20071219) ;last change
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(define *pregexp-comment-char* #\;)
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(define *pregexp-nul-char-int* #\x0)
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(define *pregexp-return-char* #\return)
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(define *pregexp-tab-char* #\tab)
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(define *pregexp-space-sensitive?* #t)
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(define pregexp-reverse!
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;the useful reverse! isn't R5RS
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(lambda (s)
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(let loop ((s s) (r '()))
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(if (null? s) r
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(let ((d (cdr s)))
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(set-cdr! s r)
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(loop d s))))))
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(define pregexp-error
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;R5RS won't give me a portable error procedure.
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;modify this as needed
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(case-lambda
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[(who) (error who "an error occurred")]
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[(who msg . args) (apply error who (format "~a" msg) args)]))
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(define pregexp-read-pattern
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(lambda (s i n)
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(if (>= i n)
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(list
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(list ':or (list ':seq)) i)
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(let loop ((branches '()) (i i))
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(if (or (>= i n)
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(char=? (string-ref s i) #\)))
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(list (cons ':or (pregexp-reverse! branches)) i)
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(let ((vv (pregexp-read-branch
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s
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(if (char=? (string-ref s i) #\|) (+ i 1) i) n)))
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(loop (cons (car vv) branches) (cadr vv))))))))
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(define pregexp-read-branch
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(lambda (s i n)
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(let loop ((pieces '()) (i i))
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(cond ((>= i n)
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(list (cons ':seq (pregexp-reverse! pieces)) i))
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((let ((c (string-ref s i)))
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(or (char=? c #\|)
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(char=? c #\))))
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(list (cons ':seq (pregexp-reverse! pieces)) i))
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(else (let ((vv (pregexp-read-piece s i n)))
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(loop (cons (car vv) pieces) (cadr vv))))))))
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(define pregexp-read-piece
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(lambda (s i n)
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(let ((c (string-ref s i)))
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(case c
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((#\^) (list ':bos (+ i 1)))
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((#\$) (list ':eos (+ i 1)))
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((#\.) (pregexp-wrap-quantifier-if-any
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(list ':any (+ i 1)) s n))
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((#\[) (let ((i+1 (+ i 1)))
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(pregexp-wrap-quantifier-if-any
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(case (and (< i+1 n) (string-ref s i+1))
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((#\^)
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(let ((vv (pregexp-read-char-list s (+ i 2) n)))
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(list (list ':neg-char (car vv)) (cadr vv))))
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(else (pregexp-read-char-list s i+1 n)))
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s n)))
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((#\()
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(pregexp-wrap-quantifier-if-any
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(pregexp-read-subpattern s (+ i 1) n) s n))
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((#\\ )
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(pregexp-wrap-quantifier-if-any
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(cond ((pregexp-read-escaped-number s i n) =>
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(lambda (num-i)
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(list (list ':backref (car num-i)) (cadr num-i))))
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((pregexp-read-escaped-char s i n) =>
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(lambda (char-i)
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(list (car char-i) (cadr char-i))))
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(else (pregexp-error 'pregexp-read-piece 'backslash)))
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s n))
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(else
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(if (or *pregexp-space-sensitive?*
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(and (not (char-whitespace? c))
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(not (char=? c *pregexp-comment-char*))))
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(pregexp-wrap-quantifier-if-any
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(list c (+ i 1)) s n)
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(let loop ((i i) (in-comment? #f))
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(if (>= i n) (list ':empty i)
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(let ((c (string-ref s i)))
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(cond (in-comment?
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(loop (+ i 1)
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(not (char=? c #\newline))))
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((char-whitespace? c)
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(loop (+ i 1) #f))
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((char=? c *pregexp-comment-char*)
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(loop (+ i 1) #t))
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(else (list ':empty i))))))))))))
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(define pregexp-read-escaped-number
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(lambda (s i n)
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; s[i] = \
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(and (< (+ i 1) n) ;must have at least something following \
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(let ((c (string-ref s (+ i 1))))
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(and (char-numeric? c)
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(let loop ((i (+ i 2)) (r (list c)))
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(if (>= i n)
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(list (string->number
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(list->string (pregexp-reverse! r))) i)
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(let ((c (string-ref s i)))
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(if (char-numeric? c)
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(loop (+ i 1) (cons c r))
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(list (string->number
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(list->string (pregexp-reverse! r)))
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i))))))))))
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(define pregexp-read-escaped-char
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(lambda (s i n)
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; s[i] = \
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(and (< (+ i 1) n)
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(let ((c (string-ref s (+ i 1))))
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(case c
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((#\b) (list ':wbdry (+ i 2)))
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((#\B) (list ':not-wbdry (+ i 2)))
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((#\d) (list ':digit (+ i 2)))
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((#\D) (list '(:neg-char :digit) (+ i 2)))
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((#\n) (list #\newline (+ i 2)))
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((#\r) (list *pregexp-return-char* (+ i 2)))
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((#\s) (list ':space (+ i 2)))
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((#\S) (list '(:neg-char :space) (+ i 2)))
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((#\t) (list *pregexp-tab-char* (+ i 2)))
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((#\w) (list ':word (+ i 2)))
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((#\W) (list '(:neg-char :word) (+ i 2)))
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(else (list c (+ i 2))))))))
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(define pregexp-read-posix-char-class
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(lambda (s i n)
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; lbrack, colon already read
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(let ((neg? #f))
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(let loop ((i i) (r (list #\:)))
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(if (>= i n)
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(pregexp-error 'pregexp-read-posix-char-class)
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(let ((c (string-ref s i)))
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(cond ((char=? c #\^)
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(set! neg? #t)
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(loop (+ i 1) r))
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((char-alphabetic? c)
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(loop (+ i 1) (cons c r)))
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((char=? c #\:)
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(if (or (>= (+ i 1) n)
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(not (char=? (string-ref s (+ i 1)) #\])))
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(pregexp-error 'pregexp-read-posix-char-class)
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(let ((posix-class
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(string->symbol
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(list->string (pregexp-reverse! r)))))
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(list (if neg? (list ':neg-char posix-class)
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posix-class)
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(+ i 2)))))
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(else
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(pregexp-error 'pregexp-read-posix-char-class)))))))))
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(define pregexp-read-cluster-type
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(lambda (s i n)
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; s[i-1] = left-paren
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(let ((c (string-ref s i)))
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(case c
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((#\?)
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(let ((i (+ i 1)))
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(case (string-ref s i)
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((#\:) (list '() (+ i 1)))
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((#\=) (list '(:lookahead) (+ i 1)))
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((#\!) (list '(:neg-lookahead) (+ i 1)))
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((#\>) (list '(:no-backtrack) (+ i 1)))
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((#\<)
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(list (case (string-ref s (+ i 1))
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((#\=) '(:lookbehind))
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((#\!) '(:neg-lookbehind))
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(else (pregexp-error 'pregexp-read-cluster-type)))
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(+ i 2)))
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(else (let loop ((i i) (r '()) (inv? #f))
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(let ((c (string-ref s i)))
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(case c
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((#\-) (loop (+ i 1) r #t))
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((#\i) (loop (+ i 1)
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(cons (if inv? ':case-sensitive
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':case-insensitive) r) #f))
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((#\x)
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(set! *pregexp-space-sensitive?* inv?)
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(loop (+ i 1) r #f))
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((#\:) (list r (+ i 1)))
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(else (pregexp-error
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'pregexp-read-cluster-type)))))))))
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(else (list '(:sub) i))))))
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(define pregexp-read-subpattern
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(lambda (s i n)
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(let* ((remember-space-sensitive? *pregexp-space-sensitive?*)
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(ctyp-i (pregexp-read-cluster-type s i n))
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(ctyp (car ctyp-i))
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(i (cadr ctyp-i))
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(vv (pregexp-read-pattern s i n)))
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(set! *pregexp-space-sensitive?* remember-space-sensitive?)
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(let ((vv-re (car vv))
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(vv-i (cadr vv)))
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(if (and (< vv-i n)
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(char=? (string-ref s vv-i)
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#\)))
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(list
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(let loop ((ctyp ctyp) (re vv-re))
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(if (null? ctyp) re
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(loop (cdr ctyp)
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(list (car ctyp) re))))
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(+ vv-i 1))
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(pregexp-error 'pregexp-read-subpattern))))))
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(define pregexp-wrap-quantifier-if-any
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(lambda (vv s n)
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(let ((re (car vv)))
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(let loop ((i (cadr vv)))
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(if (>= i n) vv
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(let ((c (string-ref s i)))
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(if (and (char-whitespace? c) (not *pregexp-space-sensitive?*))
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(loop (+ i 1))
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(case c
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((#\* #\+ #\? #\{)
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(let* ((new-re (list ':between 'minimal?
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'at-least 'at-most re))
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(new-vv (list new-re 'next-i)))
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(case c
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((#\*) (set-car! (cddr new-re) 0)
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(set-car! (cdddr new-re) #f))
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((#\+) (set-car! (cddr new-re) 1)
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(set-car! (cdddr new-re) #f))
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((#\?) (set-car! (cddr new-re) 0)
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(set-car! (cdddr new-re) 1))
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((#\{) (let ((pq (pregexp-read-nums s (+ i 1) n)))
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(if (not pq)
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(pregexp-error
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'pregexp-wrap-quantifier-if-any
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'left-brace-must-be-followed-by-number))
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(set-car! (cddr new-re) (car pq))
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(set-car! (cdddr new-re) (cadr pq))
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(set! i (caddr pq)))))
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(let loop ((i (+ i 1)))
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(if (>= i n)
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(begin (set-car! (cdr new-re) #f)
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(set-car! (cdr new-vv) i))
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(let ((c (string-ref s i)))
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(cond ((and (char-whitespace? c)
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(not *pregexp-space-sensitive?*))
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(loop (+ i 1)))
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((char=? c #\?)
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(set-car! (cdr new-re) #t)
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(set-car! (cdr new-vv) (+ i 1)))
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(else (set-car! (cdr new-re) #f)
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(set-car! (cdr new-vv) i))))))
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new-vv))
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(else vv)))))))))
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;
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(define pregexp-read-nums
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(lambda (s i n)
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; s[i-1] = {
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; returns (p q k) where s[k] = }
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(let loop ((p '()) (q '()) (k i) (reading 1))
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(if (>= k n) (pregexp-error 'pregexp-read-nums))
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(let ((c (string-ref s k)))
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(cond ((char-numeric? c)
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(if (= reading 1)
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(loop (cons c p) q (+ k 1) 1)
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(loop p (cons c q) (+ k 1) 2)))
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((and (char-whitespace? c) (not *pregexp-space-sensitive?*))
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(loop p q (+ k 1) reading))
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((and (char=? c #\,) (= reading 1))
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(loop p q (+ k 1) 2))
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((char=? c #\})
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(let ((p (string->number (list->string (pregexp-reverse! p))))
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(q (string->number (list->string (pregexp-reverse! q)))))
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(cond ((and (not p) (= reading 1)) (list 0 #f k))
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((= reading 1) (list p p k))
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(else (list p q k)))))
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(else #f))))))
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(define pregexp-invert-char-list
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(lambda (vv)
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(set-car! (car vv) ':none-of-chars)
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vv))
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;
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(define pregexp-read-char-list
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(lambda (s i n)
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(let loop ((r '()) (i i))
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(if (>= i n)
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(pregexp-error 'pregexp-read-char-list
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'character-class-ended-too-soon)
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(let ((c (string-ref s i)))
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(case c
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((#\]) (if (null? r)
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(loop (cons c r) (+ i 1))
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(list (cons ':one-of-chars (pregexp-reverse! r))
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(+ i 1))))
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((#\\ )
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(let ((char-i (pregexp-read-escaped-char s i n)))
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(if char-i (loop (cons (car char-i) r) (cadr char-i))
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(pregexp-error 'pregexp-read-char-list 'backslash))))
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((#\-) (if (or (null? r)
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(let ((i+1 (+ i 1)))
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(and (< i+1 n)
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(char=? (string-ref s i+1) #\]))))
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(loop (cons c r) (+ i 1))
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(let ((c-prev (car r)))
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(if (char? c-prev)
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(loop (cons (list ':char-range c-prev
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(string-ref s (+ i 1))) (cdr r))
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(+ i 2))
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(loop (cons c r) (+ i 1))))))
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((#\[) (if (char=? (string-ref s (+ i 1)) #\:)
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(let ((posix-char-class-i
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(pregexp-read-posix-char-class s (+ i 2) n)))
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(loop (cons (car posix-char-class-i) r)
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(cadr posix-char-class-i)))
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(loop (cons c r) (+ i 1))))
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(else (loop (cons c r) (+ i 1)))))))))
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;
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(define pregexp-string-match
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(lambda (s1 s i n sk fk)
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(let ((n1 (string-length s1)))
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(if (> n1 n) (fk)
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(let loop ((j 0) (k i))
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(cond ((>= j n1) (sk k))
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((>= k n) (fk))
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((char=? (string-ref s1 j) (string-ref s k))
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(loop (+ j 1) (+ k 1)))
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(else (fk))))))))
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(define pregexp-char-word?
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(lambda (c)
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;too restrictive for Scheme but this
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;is what \w is in most regexp notations
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(or (char-alphabetic? c)
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(char-numeric? c)
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(char=? c #\_))))
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(define pregexp-at-word-boundary?
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(lambda (s i n)
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(or (= i 0) (>= i n)
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(let ((c/i (string-ref s i))
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(c/i-1 (string-ref s (- i 1))))
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(let ((c/i/w? (pregexp-check-if-in-char-class?
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c/i ':word))
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(c/i-1/w? (pregexp-check-if-in-char-class?
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c/i-1 ':word)))
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(or (and c/i/w? (not c/i-1/w?))
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(and (not c/i/w?) c/i-1/w?)))))))
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(define pregexp-check-if-in-char-class?
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(lambda (c char-class)
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(case char-class
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((:any) (not (char=? c #\newline)))
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;
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((:alnum) (or (char-alphabetic? c) (char-numeric? c)))
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((:alpha) (char-alphabetic? c))
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((:ascii) (< (char->integer c) 128))
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((:blank) (or (char=? c #\space) (char=? c *pregexp-tab-char*)))
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((:cntrl) (< (char->integer c) 32))
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((:digit) (char-numeric? c))
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((:graph) (and (>= (char->integer c) 32)
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(not (char-whitespace? c))))
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((:lower) (char-lower-case? c))
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((:print) (>= (char->integer c) 32))
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((:punct) (and (>= (char->integer c) 32)
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(not (char-whitespace? c))
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(not (char-alphabetic? c))
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(not (char-numeric? c))))
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((:space) (char-whitespace? c))
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((:upper) (char-upper-case? c))
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((:word) (or (char-alphabetic? c)
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(char-numeric? c)
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(char=? c #\_)))
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((:xdigit) (or (char-numeric? c)
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(char-ci=? c #\a) (char-ci=? c #\b)
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(char-ci=? c #\c) (char-ci=? c #\d)
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(char-ci=? c #\e) (char-ci=? c #\f)))
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(else (pregexp-error 'pregexp-check-if-in-char-class?)))))
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(define pregexp-list-ref
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(lambda (s i)
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;like list-ref but returns #f if index is
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;out of bounds
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(let loop ((s s) (k 0))
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(cond ((null? s) #f)
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((= k i) (car s))
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(else (loop (cdr s) (+ k 1)))))))
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;re is a compiled regexp. It's a list that can't be
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;nil. pregexp-match-positions-aux returns a 2-elt list whose
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;car is the string-index following the matched
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;portion and whose cadr contains the submatches.
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;The proc returns false if there's no match.
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;Am spelling loop- as loup- because these shouldn't
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;be translated into CL loops by scm2cl (although
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;they are tail-recursive in Scheme)
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(define pregexp-make-backref-list
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(lambda (re)
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(let sub ((re re))
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(if (pair? re)
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(let ((car-re (car re))
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(sub-cdr-re (sub (cdr re))))
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(if (eqv? car-re ':sub)
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(cons (cons re #f) sub-cdr-re)
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(append (sub car-re) sub-cdr-re)))
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'()))))
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(define pregexp-match-positions-aux
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(lambda (re s sn start n i)
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(let ((identity (lambda (x) x))
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(backrefs (pregexp-make-backref-list re))
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(case-sensitive? #t))
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(let sub ((re re) (i i) (sk identity) (fk (lambda () #f)))
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;(printf "sub ~s ~s\n" i re)
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(cond ((eqv? re ':bos)
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;(if (= i 0) (sk i) (fk))
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(if (= i start) (sk i) (fk))
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)
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((eqv? re ':eos)
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;(if (>= i sn) (sk i) (fk))
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(if (>= i n) (sk i) (fk))
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)
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((eqv? re ':empty)
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(sk i))
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((eqv? re ':wbdry)
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(if (pregexp-at-word-boundary? s i n)
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(sk i)
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(fk)))
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((eqv? re ':not-wbdry)
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(if (pregexp-at-word-boundary? s i n)
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(fk)
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(sk i)))
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((and (char? re) (< i n))
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;(printf "bingo\n")
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(if ((if case-sensitive? char=? char-ci=?)
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(string-ref s i) re)
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(sk (+ i 1)) (fk)))
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((and (not (pair? re)) (< i n))
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(if (pregexp-check-if-in-char-class?
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(string-ref s i) re)
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(sk (+ i 1)) (fk)))
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((and (pair? re) (eqv? (car re) ':char-range) (< i n))
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(let ((c (string-ref s i)))
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(if (let ((c< (if case-sensitive? char<=? char-ci<=?)))
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(and (c< (cadr re) c)
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(c< c (caddr re))))
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(sk (+ i 1)) (fk))))
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((pair? re)
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(case (car re)
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((:char-range)
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(if (>= i n) (fk)
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(pregexp-error 'pregexp-match-positions-aux)))
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((:one-of-chars)
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(if (>= i n) (fk)
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(let loup-one-of-chars ((chars (cdr re)))
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(if (null? chars) (fk)
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(sub (car chars) i sk
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(lambda ()
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(loup-one-of-chars (cdr chars))))))))
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((:neg-char)
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(if (>= i n) (fk)
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(sub (cadr re) i
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(lambda (i1) (fk))
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(lambda () (sk (+ i 1))))))
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((:seq)
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(let loup-seq ((res (cdr re)) (i i))
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(if (null? res) (sk i )
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(sub (car res) i
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(lambda (i1 )
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(loup-seq (cdr res) i1 ))
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fk))))
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((:or)
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(let loup-or ((res (cdr re)))
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(if (null? res) (fk)
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(sub (car res) i
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(lambda (i1 )
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(or (sk i1 )
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(loup-or (cdr res))))
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(lambda () (loup-or (cdr res)))))))
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((:backref)
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(let* ((c (pregexp-list-ref backrefs (cadr re)))
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(backref
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(cond (c => cdr)
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(else
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(pregexp-error 'pregexp-match-positions-aux
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'non-existent-backref re)
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#f))))
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(if backref
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(pregexp-string-match
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(substring s (car backref) (cdr backref))
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s i n (lambda (i) (sk i)) fk)
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(sk i))))
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((:sub)
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(sub (cadr re) i
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(lambda (i1)
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(set-cdr! (assv re backrefs) (cons i i1))
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(sk i1)) fk))
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((:lookahead)
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(let ((found-it?
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(sub (cadr re) i
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identity (lambda () #f))))
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(if found-it? (sk i) (fk))))
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((:neg-lookahead)
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(let ((found-it?
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(sub (cadr re) i
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identity (lambda () #f))))
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(if found-it? (fk) (sk i))))
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((:lookbehind)
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(let ((n-actual n) (sn-actual sn))
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(set! n i) (set! sn i)
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(let ((found-it?
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(sub (list ':seq '(:between #f 0 #f :any)
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(cadr re) ':eos) 0
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identity (lambda () #f))))
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(set! n n-actual) (set! sn sn-actual)
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(if found-it? (sk i) (fk)))))
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((:neg-lookbehind)
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(let ((n-actual n) (sn-actual sn))
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(set! n i) (set! sn i)
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(let ((found-it?
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(sub (list ':seq '(:between #f 0 #f :any)
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(cadr re) ':eos) 0
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identity (lambda () #f))))
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(set! n n-actual) (set! sn sn-actual)
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(if found-it? (fk) (sk i)))))
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((:no-backtrack)
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(let ((found-it? (sub (cadr re) i
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identity (lambda () #f))))
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(if found-it?
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(sk found-it?)
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(fk))))
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((:case-sensitive :case-insensitive)
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(let ((old case-sensitive?))
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(set! case-sensitive?
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(eqv? (car re) ':case-sensitive))
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(sub (cadr re) i
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(lambda (i1)
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(set! case-sensitive? old)
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(sk i1))
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(lambda ()
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(set! case-sensitive? old)
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(fk)))))
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((:between)
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(let* ((maximal? (not (cadr re)))
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(p (caddr re))
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(q (cadddr re))
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(could-loop-infinitely? (and maximal? (not q)))
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(re (car (cddddr re))))
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(let loup-p ((k 0) (i i) )
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(if (< k p)
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(sub re i
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(lambda (i1 )
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(if (and could-loop-infinitely?
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(= i1 i))
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(pregexp-error
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'pregexp-match-positions-aux
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'greedy-quantifier-operand-could-be-empty))
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(loup-p (+ k 1) i1 ))
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fk)
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(let ((q (and q (- q p))))
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(let loup-q ((k 0) (i i))
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(let ((fk (lambda ()
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(sk i ))))
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(if (and q (>= k q)) (fk)
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(if maximal?
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(sub re i
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(lambda (i1)
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(if (and could-loop-infinitely?
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(= i1 i))
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(pregexp-error
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'pregexp-match-positions-aux
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'greedy-quantifier-operand-could-be-empty))
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(or (loup-q (+ k 1) i1)
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(fk)))
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fk)
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(or (fk)
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(sub re i
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(lambda (i1)
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(loup-q (+ k 1) i1))
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fk)))))))))))
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(else (pregexp-error 'pregexp-match-positions-aux))))
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((>= i n) (fk))
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(else (pregexp-error 'pregexp-match-positions-aux))))
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;(printf "done\n")
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(let ((backrefs (map cdr backrefs)))
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(and (car backrefs) backrefs)))))
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(define pregexp-replace-aux
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(lambda (str ins n backrefs)
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(let loop ((i 0) (r ""))
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(if (>= i n) r
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(let ((c (string-ref ins i)))
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(if (char=? c #\\ )
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(let* ((br-i (pregexp-read-escaped-number ins i n))
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(br (if br-i (car br-i)
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(if (char=? (string-ref ins (+ i 1)) #\&) 0
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#f)))
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(i (if br-i (cadr br-i)
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(if br (+ i 2)
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(+ i 1)))))
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(if (not br)
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(let ((c2 (string-ref ins i)))
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(loop (+ i 1)
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(if (char=? c2 #\$) r
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(string-append r (string c2)))))
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(loop i
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(let ((backref (pregexp-list-ref backrefs br)))
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(if backref
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(string-append r
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(substring str (car backref) (cdr backref)))
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r)))))
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(loop (+ i 1) (string-append r (string c)))))))))
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(define pregexp-proc
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(let ([pregexp
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(lambda (s)
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(set! *pregexp-space-sensitive?* #t) ;in case it got corrupted
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(list ':sub (car (pregexp-read-pattern s 0 (string-length s)))))])
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pregexp))
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(define-syntax pregexp
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(lambda (x) ;;; aziz's touch
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(syntax-case x ()
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[(_ str)
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(string? (syntax->datum #'str))
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#'(let-syntax ([foo
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(lambda (t)
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(with-syntax ([c (datum->syntax #'_
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(pregexp-proc str))])
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#'(quote c)))])
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foo)]
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[(_ args ...) #'(pregexp-proc args ...)]
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[id (identifier? #'id) #'pregexp-proc])))
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(define-syntax define-regexp-proc
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(lambda (stx)
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(syntax-case stx ()
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[(_ name expr)
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(with-syntax ([(name^) (generate-temporaries (list #'name))])
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#'(begin
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(define name^ expr)
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(define-syntax name
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(lambda (x)
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(syntax-case x ()
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[(_ str args (... ...)) (string? #'str)
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#'(name^ (pregexp str) args (... ...))]
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[(_ args (... ...))
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#'(name^ args (... ...))]
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[id (identifier? #'id) #'name^])))))])))
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(define-regexp-proc pregexp-match-positions
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(lambda (pat str . opt-args)
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(cond ((string? pat) (set! pat (pregexp pat)))
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((pair? pat) #t)
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(else (pregexp-error 'pregexp-match-positions
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'pattern-must-be-compiled-or-string-regexp
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pat)))
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(let* ((str-len (string-length str))
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(start (if (null? opt-args) 0
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(let ((start (car opt-args)))
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(set! opt-args (cdr opt-args))
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start)))
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(end (if (null? opt-args) str-len
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(car opt-args))))
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(let loop ((i start))
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(and (<= i end)
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(or (pregexp-match-positions-aux
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pat str str-len start end i)
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(loop (+ i 1))))))))
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(define-regexp-proc pregexp-match
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(lambda (pat str . opt-args)
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(let ((ix-prs (apply pregexp-match-positions pat str opt-args)))
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(and ix-prs
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(map
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(lambda (ix-pr)
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(and ix-pr
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(substring str (car ix-pr) (cdr ix-pr))))
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ix-prs)))))
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(define-regexp-proc pregexp-split
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(lambda (pat str)
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;split str into substrings, using pat as delimiter
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(let ((n (string-length str))
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;;; aziz
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(pat (if (string? pat) (pregexp pat) pat)))
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(let loop ((i 0) (r '()) (picked-up-one-undelimited-char? #f))
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(cond ((>= i n) (pregexp-reverse! r))
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((pregexp-match-positions pat str i n)
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=>
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(lambda (y)
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(let ((jk (car y)))
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(let ((j (car jk)) (k (cdr jk)))
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;(printf "j = ~a; k = ~a; i = ~a~n" j k i)
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(cond ((= j k)
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;(printf "producing ~s~n" (substring str i (+ j 1)))
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(loop (+ k 1)
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(cons (substring str i (+ j 1)) r) #t))
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((and (= j i) picked-up-one-undelimited-char?)
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(loop k r #f))
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(else
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;(printf "producing ~s~n" (substring str i j))
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(loop k (cons (substring str i j) r) #f)))))))
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(else (loop n (cons (substring str i n) r) #f)))))))
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(define-regexp-proc pregexp-replace
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(lambda (pat str ins)
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(let* ((n (string-length str))
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(pp (pregexp-match-positions pat str 0 n)))
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(if (not pp) str
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(let ((ins-len (string-length ins))
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(m-i (caar pp))
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(m-n (cdar pp)))
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(string-append
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(substring str 0 m-i)
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(pregexp-replace-aux str ins ins-len pp)
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(substring str m-n n)))))))
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(define-regexp-proc pregexp-replace*
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(lambda (pat str ins)
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;return str with every occurrence of pat
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;replaced by ins
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(let ((pat (if (string? pat) (pregexp pat) pat))
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(n (string-length str))
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(ins-len (string-length ins)))
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(let loop ((i 0) (r ""))
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;i = index in str to start replacing from
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;r = already calculated prefix of answer
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(if (>= i n) r
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(let ((pp (pregexp-match-positions pat str i n)))
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(if (not pp)
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(if (= i 0)
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;this implies pat didn't match str at
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;all, so let's return original str
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str
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;else: all matches already found and
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;replaced in r, so let's just
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;append the rest of str
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(string-append
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r (substring str i n)))
|
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(loop (cdar pp)
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(string-append
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r
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(substring str i (caar pp))
|
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(pregexp-replace-aux str ins ins-len pp))))))))))
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(define pregexp-quote
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(lambda (s)
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(let loop ((i (- (string-length s) 1)) (r '()))
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(if (< i 0) (list->string r)
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(loop (- i 1)
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(let ((c (string-ref s i)))
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(if (memv c '(#\\ #\. #\? #\* #\+ #\| #\^ #\$
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#\[ #\] #\{ #\} #\( #\)))
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(cons #\\ (cons c r))
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(cons c r))))))))
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)
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