ice-9/regex.scm

   1 ;;;;    Copyright (C) 1997 Free Software Foundation, Inc.
   2 ;;;;
   3 ;;;; This program is free software; you can redistribute it and/or modify
   4 ;;;; it under the terms of the GNU General Public License as published by
   5 ;;;; the Free Software Foundation; either version 2, or (at your option)
   6 ;;;; any later version.
   7 ;;;;
   8 ;;;; This program is distributed in the hope that it will be useful,
   9 ;;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  10 ;;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11 ;;;; GNU General Public License for more details.
  12 ;;;;
  13 ;;;; You should have received a copy of the GNU General Public License
  14 ;;;; along with this software; see the file COPYING.  If not, write to
  15 ;;;; the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
  16 ;;;; Boston, MA 02111-1307 USA
  17 ;;;;
  18 \f
  19 ;;;; POSIX regex support functions.
  20
  21 (define-module (ice-9 regex))
  22
  23 ;;; FIXME:
  24 ;;;   It is not clear what should happen if a `match' function
  25 ;;;   is passed a `match number' which is out of bounds for the
  26 ;;;   regexp match: return #f, or throw an error?  These routines
  27 ;;;   throw an out-of-range error.
  28
  29 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
  30 ;;;; These procedures are not defined in SCSH, but I found them useful.
  31
  32 (define-public (match:count match)
  33   (- (vector-length match) 1))
  34
  35 (define-public (match:string match)
  36   (vector-ref match 0))
  37
  38 (define-public (match:prefix match)
  39   (make-shared-substring (match:string match)
  40                          0
  41                          (match:start match 0)))
  42
  43 (define-public (match:suffix match)
  44   (make-shared-substring (match:string match)
  45                          (match:end match 0)))
  46
  47 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
  48 ;;;; SCSH compatibility routines.
  49
  50 (define-public (regexp-match? match)
  51   (and (vector? match)
  52        (string? (vector-ref match 0))
  53        (let loop ((i 1))
  54          (cond ((>= i (vector-length match)) #t)
  55                ((and (pair? (vector-ref match i))
  56                      (integer? (car (vector-ref match i)))
  57                      (integer? (cdr (vector-ref match i))))
  58                 (loop (+ 1 i)))
  59                (else #f)))))
  60
  61 (define-public (regexp-quote regexp)
  62   (call-with-output-string
  63    (lambda (p)
  64      (let loop ((i 0))
  65        (and (< i (string-length regexp))
  66             (begin
  67               (case (string-ref regexp i)
  68                 ((#\* #\. #\( #\) #\+ #\? #\\ #\^ #\$ #\{ #\})
  69                  (write-char #\\ p)))
  70               (write-char (string-ref regexp i) p)
  71               (loop (1+ i))))))))
  72
  73 (define-public (match:start match . args)
  74   (let* ((matchnum (if (pair? args)
  75                        (+ 1 (car args))
  76                        1))
  77          (start (car (vector-ref match matchnum))))
  78     (if (= start -1) #f start)))
  79
  80 (define-public (match:end match . args)
  81   (let* ((matchnum (if (pair? args)
  82                        (+ 1 (car args))
  83                        1))
  84          (end (cdr (vector-ref match matchnum))))
  85     (if (= end -1) #f end)))
  86
  87 (define-public (match:substring match . args)
  88   (let* ((matchnum (if (pair? args)
  89                        (car args)
  90                        0))
  91          (start (match:start match matchnum))
  92          (end   (match:end match matchnum)))
  93     (and start end (make-shared-substring (match:string match)
  94                                           start
  95                                           end))))
  96
  97 (define-public (string-match pattern str . args)
  98   (let ((rx (make-regexp pattern))
  99         (start (if (pair? args) (car args) 0)))
 100     (regexp-exec rx str start)))
 101
 102 (define-public (regexp-substitute port match . items)
 103   ;; If `port' is #f, send output to a string.
 104   (if (not port)
 105       (call-with-output-string
 106        (lambda (p)
 107          (apply regexp-substitute p match items)))
 108
 109       ;; Otherwise, process each substitution argument in `items'.
 110       (for-each (lambda (obj)
 111                   (cond ((string? obj)   (display obj port))
 112                         ((integer? obj)  (display (match:substring match obj) port))
 113                         ((eq? 'pre obj)  (display (match:prefix match) port))
 114                         ((eq? 'post obj) (display (match:suffix match) port))
 115                         (else (error 'wrong-type-arg obj))))
 116                 items)))
 117
 118 (define-public (regexp-substitute/global port regexp string . items)
 119   ;; If `port' is #f, send output to a string.
 120   (if (not port)
 121       (call-with-output-string
 122        (lambda (p)
 123          (apply regexp-substitute/global p regexp string items)))
 124
 125       ;; Otherwise, compile the regexp and match it against the
 126       ;; string, looping if 'post is encountered in `items'.
 127       (let ((rx (make-regexp regexp)))
 128         (let next-match ((str string))
 129           (let ((match (regexp-exec rx str)))
 130             (if (not match)
 131                 (display str port)
 132
 133                 ;; Process all of the items for this match.
 134                 (for-each
 135                  (lambda (obj)
 136                    (cond
 137                     ((string? obj)    (display obj port))
 138                     ((integer? obj)   (display (match:substring match obj) port))
 139                     ((procedure? obj) (display (obj match) port))
 140                     ((eq? 'pre obj)   (display (match:prefix match) port))
 141                     ((eq? 'post obj)  (next-match (match:suffix match)))
 142                     (else (error 'wrong-type-arg obj))))
 143                  items)))))))
 144