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1 | ;;;; string-fun.scm --- string manipulation functions |
2 | ;;;; | |
1011dac0 | 3 | ;;;; Copyright (C) 1995, 1996, 1997, 1999 Free Software Foundation, Inc. |
6a4d3cfd JB |
4 | ;;;; |
5 | ;;;; This program is free software; you can redistribute it and/or modify | |
6 | ;;;; it under the terms of the GNU General Public License as published by | |
7 | ;;;; the Free Software Foundation; either version 2, or (at your option) | |
8 | ;;;; any later version. | |
9 | ;;;; | |
10 | ;;;; This program is distributed in the hope that it will be useful, | |
11 | ;;;; but WITHOUT ANY WARRANTY; without even the implied warranty of | |
12 | ;;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
13 | ;;;; GNU General Public License for more details. | |
14 | ;;;; | |
15 | ;;;; You should have received a copy of the GNU General Public License | |
16 | ;;;; along with this software; see the file COPYING. If not, write to | |
17 | ;;;; the Free Software Foundation, Inc., 59 Temple Place, Suite 330, | |
18 | ;;;; Boston, MA 02111-1307 USA | |
19 | ;;;; | |
20 | \f | |
a6401ee0 JB |
21 | (define-module (ice-9 string-fun)) |
22 | ||
23 | ;;;; | |
24 | ;;; | |
25 | ;;; Various string funcitons, particularly those that take | |
26 | ;;; advantage of the "shared substring" capability. | |
27 | ;;; | |
28 | \f | |
29 | ;;; {String Fun: Dividing Strings Into Fields} | |
30 | ;;; | |
31 | ;;; The names of these functions are very regular. | |
32 | ;;; Here is a grammar of a call to one of these: | |
33 | ;;; | |
34 | ;;; <string-function-invocation> | |
35 | ;;; := (<action>-<seperator-disposition>-<seperator-determination> <seperator-param> <str> <ret>) | |
36 | ;;; | |
37 | ;;; <str> = the string | |
38 | ;;; | |
39 | ;;; <ret> = The continuation. String functions generally return | |
40 | ;;; multiple values by passing them to this procedure. | |
41 | ;;; | |
42 | ;;; <action> = split | |
43 | ;;; | separate-fields | |
44 | ;;; | |
45 | ;;; "split" means to divide a string into two parts. | |
46 | ;;; <ret> will be called with two arguments. | |
47 | ;;; | |
48 | ;;; "separate-fields" means to divide a string into as many | |
49 | ;;; parts as possible. <ret> will be called with | |
50 | ;;; however many fields are found. | |
51 | ;;; | |
52 | ;;; <seperator-disposition> = before | |
53 | ;;; | after | |
54 | ;;; | discarding | |
55 | ;;; | |
56 | ;;; "before" means to leave the seperator attached to | |
57 | ;;; the beginning of the field to its right. | |
58 | ;;; "after" means to leave the seperator attached to | |
59 | ;;; the end of the field to its left. | |
60 | ;;; "discarding" means to discard seperators. | |
61 | ;;; | |
62 | ;;; Other dispositions might be handy. For example, "isolate" | |
63 | ;;; could mean to treat the separator as a field unto itself. | |
64 | ;;; | |
65 | ;;; <seperator-determination> = char | |
66 | ;;; | predicate | |
67 | ;;; | |
68 | ;;; "char" means to use a particular character as field seperator. | |
69 | ;;; "predicate" means to check each character using a particular predicate. | |
70 | ;;; | |
71 | ;;; Other determinations might be handy. For example, "character-set-member". | |
72 | ;;; | |
73 | ;;; <seperator-param> = A parameter that completes the meaning of the determinations. | |
74 | ;;; For example, if the determination is "char", then this parameter | |
75 | ;;; says which character. If it is "predicate", the parameter is the | |
76 | ;;; predicate. | |
77 | ;;; | |
78 | ;;; | |
79 | ;;; For example: | |
80 | ;;; | |
81 | ;;; (separate-fields-discarding-char #\, "foo, bar, baz, , bat" list) | |
82 | ;;; => ("foo" " bar" " baz" " " " bat") | |
83 | ;;; | |
84 | ;;; (split-after-char #\- 'an-example-of-split list) | |
85 | ;;; => ("an-" "example-of-split") | |
86 | ;;; | |
87 | ;;; As an alternative to using a determination "predicate", or to trying to do anything | |
88 | ;;; complicated with these functions, consider using regular expressions. | |
89 | ;;; | |
90 | ||
91 | (define-public (split-after-char char str ret) | |
92 | (let ((end (cond | |
93 | ((string-index str char) => 1+) | |
94 | (else (string-length str))))) | |
95 | (ret (make-shared-substring str 0 end) | |
96 | (make-shared-substring str end)))) | |
97 | ||
98 | (define-public (split-before-char char str ret) | |
99 | (let ((end (or (string-index str char) | |
100 | (string-length str)))) | |
101 | (ret (make-shared-substring str 0 end) | |
102 | (make-shared-substring str end)))) | |
103 | ||
104 | (define-public (split-discarding-char char str ret) | |
105 | (let ((end (string-index str char))) | |
106 | (if (not end) | |
107 | (ret str "") | |
108 | (ret (make-shared-substring str 0 end) | |
109 | (make-shared-substring str (1+ end)))))) | |
110 | ||
111 | (define-public (split-after-char-last char str ret) | |
112 | (let ((end (cond | |
113 | ((string-rindex str char) => 1+) | |
114 | (else 0)))) | |
115 | (ret (make-shared-substring str 0 end) | |
116 | (make-shared-substring str end)))) | |
117 | ||
118 | (define-public (split-before-char-last char str ret) | |
119 | (let ((end (or (string-rindex str char) 0))) | |
120 | (ret (make-shared-substring str 0 end) | |
121 | (make-shared-substring str end)))) | |
122 | ||
123 | (define-public (split-discarding-char-last char str ret) | |
124 | (let ((end (string-rindex str char))) | |
125 | (if (not end) | |
126 | (ret str "") | |
127 | (ret (make-shared-substring str 0 end) | |
128 | (make-shared-substring str (1+ end)))))) | |
129 | ||
1011dac0 | 130 | (define-public (split-before-predicate pred str ret) |
a6401ee0 JB |
131 | (let loop ((n 0)) |
132 | (cond | |
133 | ((= n (string-length str)) (ret str "")) | |
134 | ((not (pred (string-ref str n))) (loop (1+ n))) | |
135 | (else (ret (make-shared-substring str 0 n) | |
136 | (make-shared-substring str n)))))) | |
1011dac0 | 137 | (define-public (split-after-predicate pred str ret) |
a6401ee0 JB |
138 | (let loop ((n 0)) |
139 | (cond | |
140 | ((= n (string-length str)) (ret str "")) | |
141 | ((not (pred (string-ref str n))) (loop (1+ n))) | |
142 | (else (ret (make-shared-substring str 0 (1+ n)) | |
143 | (make-shared-substring str (1+ n))))))) | |
144 | ||
1011dac0 | 145 | (define-public (split-discarding-predicate pred str ret) |
a6401ee0 JB |
146 | (let loop ((n 0)) |
147 | (cond | |
148 | ((= n (string-length str)) (ret str "")) | |
149 | ((not (pred (string-ref str n))) (loop (1+ n))) | |
150 | (else (ret (make-shared-substring str 0 n) | |
151 | (make-shared-substring str (1+ n))))))) | |
152 | ||
153 | (define-public (separate-fields-discarding-char ch str ret) | |
154 | (let loop ((fields '()) | |
155 | (str str)) | |
156 | (cond | |
157 | ((string-rindex str ch) | |
158 | => (lambda (w) (loop (cons (make-shared-substring str (+ 1 w)) fields) | |
159 | (make-shared-substring str 0 w)))) | |
160 | (else (apply ret str fields))))) | |
161 | ||
162 | (define-public (separate-fields-after-char ch str ret) | |
163 | (reverse | |
164 | (let loop ((fields '()) | |
165 | (str str)) | |
166 | (cond | |
167 | ((string-index str ch) | |
168 | => (lambda (w) (loop (cons (make-shared-substring str 0 (+ 1 w)) fields) | |
169 | (make-shared-substring str (+ 1 w))))) | |
170 | (else (apply ret str fields)))))) | |
171 | ||
172 | (define-public (separate-fields-before-char ch str ret) | |
173 | (let loop ((fields '()) | |
174 | (str str)) | |
175 | (cond | |
176 | ((string-rindex str ch) | |
177 | => (lambda (w) (loop (cons (make-shared-substring str w) fields) | |
178 | (make-shared-substring str 0 w)))) | |
179 | (else (apply ret str fields))))) | |
180 | ||
181 | \f | |
182 | ;;; {String Fun: String Prefix Predicates} | |
183 | ;;; | |
184 | ;;; Very simple: | |
185 | ;;; | |
186 | ;;; (define-public ((string-prefix-predicate pred?) prefix str) | |
187 | ;;; (and (<= (string-length prefix) (string-length str)) | |
188 | ;;; (pred? prefix (make-shared-substring str 0 (string-length prefix))))) | |
189 | ;;; | |
190 | ;;; (define-public string-prefix=? (string-prefix-predicate string=?)) | |
191 | ;;; | |
192 | ||
193 | (define-public ((string-prefix-predicate pred?) prefix str) | |
194 | (and (<= (string-length prefix) (string-length str)) | |
195 | (pred? prefix (make-shared-substring str 0 (string-length prefix))))) | |
196 | ||
197 | (define-public string-prefix=? (string-prefix-predicate string=?)) | |
198 | ||
199 | \f | |
200 | ;;; {String Fun: Strippers} | |
201 | ;;; | |
202 | ;;; <stripper> = sans-<removable-part> | |
203 | ;;; | |
204 | ;;; <removable-part> = surrounding-whitespace | |
205 | ;;; | trailing-whitespace | |
206 | ;;; | leading-whitespace | |
207 | ;;; | final-newline | |
208 | ;;; | |
209 | ||
210 | (define-public (sans-surrounding-whitespace s) | |
211 | (let ((st 0) | |
212 | (end (string-length s))) | |
213 | (while (and (< st (string-length s)) | |
214 | (char-whitespace? (string-ref s st))) | |
215 | (set! st (1+ st))) | |
216 | (while (and (< 0 end) | |
217 | (char-whitespace? (string-ref s (1- end)))) | |
218 | (set! end (1- end))) | |
219 | (if (< end st) | |
220 | "" | |
221 | (make-shared-substring s st end)))) | |
222 | ||
223 | (define-public (sans-trailing-whitespace s) | |
224 | (let ((st 0) | |
225 | (end (string-length s))) | |
226 | (while (and (< 0 end) | |
227 | (char-whitespace? (string-ref s (1- end)))) | |
228 | (set! end (1- end))) | |
229 | (if (< end st) | |
230 | "" | |
231 | (make-shared-substring s st end)))) | |
232 | ||
233 | (define-public (sans-leading-whitespace s) | |
234 | (let ((st 0) | |
235 | (end (string-length s))) | |
236 | (while (and (< st (string-length s)) | |
237 | (char-whitespace? (string-ref s st))) | |
238 | (set! st (1+ st))) | |
239 | (if (< end st) | |
240 | "" | |
241 | (make-shared-substring s st end)))) | |
242 | ||
243 | (define-public (sans-final-newline str) | |
244 | (cond | |
245 | ((= 0 (string-length str)) | |
246 | str) | |
247 | ||
248 | ((char=? #\nl (string-ref str (1- (string-length str)))) | |
249 | (make-shared-substring str 0 (1- (string-length str)))) | |
250 | ||
251 | (else str))) | |
252 | \f | |
253 | ;;; {String Fun: has-trailing-newline?} | |
254 | ;;; | |
255 | ||
256 | (define-public (has-trailing-newline? str) | |
257 | (and (< 0 (string-length str)) | |
258 | (char=? #\nl (string-ref str (1- (string-length str)))))) | |
259 | ||
260 | ||
261 | \f | |
262 | ;;; {String Fun: with-regexp-parts} | |
263 | ||
264 | ;;; This relies on the older, hairier regexp interface, which we don't | |
265 | ;;; particularly want to implement, and it's not used anywhere, so | |
266 | ;;; we're just going to drop it for now. | |
267 | ;;; (define-public (with-regexp-parts regexp fields str return fail) | |
268 | ;;; (let ((parts (regexec regexp str fields))) | |
269 | ;;; (if (number? parts) | |
270 | ;;; (fail parts) | |
271 | ;;; (apply return parts)))) | |
272 |