1 /*
2 * Copyright (c) 2004 Tim J. Robbins.
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 */
26 /*
27 * "Set of characters" ADT implemented as a splay tree of extents, with
28 * a lookup table cache to simplify looking up the first bunch of
29 * characters (which are presumably more common than others).
30 */
31
32 #include <assert.h>
33 #include <stdbool.h>
34 #include <stdlib.h>
35 #include <wchar.h>
36 #include <wctype.h>
37 #include "cset.h"
38
39 static struct csnode *cset_delete(struct csnode *, wchar_t);
40 static int cset_rangecmp(struct csnode *, wchar_t);
41 static struct csnode *cset_splay(struct csnode *, wchar_t);
42
43 /*
44 * cset_alloc --
45 * Allocate a set of characters.
46 */
47 struct cset *
cset_alloc(void)48 cset_alloc(void)
49 {
50 struct cset *cs;
51
52 if ((cs = malloc(sizeof (*cs))) == NULL)
53 return (NULL);
54 cs->cs_root = NULL;
55 cs->cs_classes = NULL;
56 cs->cs_havecache = false;
57 cs->cs_invert = false;
58 return (cs);
59 }
60
61 /*
62 * cset_add --
63 * Add a character to the set.
64 */
65 bool
cset_add(struct cset * cs,wchar_t ch)66 cset_add(struct cset *cs, wchar_t ch)
67 {
68 struct csnode *csn, *ncsn;
69 wchar_t oval;
70
71 cs->cs_havecache = false;
72
73 /*
74 * Inserting into empty tree; new item becomes the root.
75 */
76 if (cs->cs_root == NULL) {
77 csn = malloc(sizeof (*cs->cs_root));
78 if (csn == NULL)
79 return (false);
80 csn->csn_left = csn->csn_right = NULL;
81 csn->csn_min = csn->csn_max = ch;
82 cs->cs_root = csn;
83 return (true);
84 }
85
86 /*
87 * Splay to check whether the item already exists, and otherwise,
88 * where we should put it.
89 */
90 csn = cs->cs_root = cset_splay(cs->cs_root, ch);
91
92 /*
93 * Avoid adding duplicate nodes.
94 */
95 if (cset_rangecmp(csn, ch) == 0)
96 return (true);
97
98 /*
99 * Allocate a new node and make it the new root.
100 */
101 ncsn = malloc(sizeof (*ncsn));
102 if (ncsn == NULL)
103 return (false);
104 ncsn->csn_min = ncsn->csn_max = ch;
105 if (cset_rangecmp(csn, ch) < 0) {
106 ncsn->csn_left = csn->csn_left;
107 ncsn->csn_right = csn;
108 csn->csn_left = NULL;
109 } else {
110 ncsn->csn_right = csn->csn_right;
111 ncsn->csn_left = csn;
112 csn->csn_right = NULL;
113 }
114 cs->cs_root = ncsn;
115
116 /*
117 * Coalesce with left and right neighbours if possible.
118 */
119 if (ncsn->csn_left != NULL) {
120 ncsn->csn_left = cset_splay(ncsn->csn_left, ncsn->csn_min - 1);
121 if (ncsn->csn_left->csn_max == ncsn->csn_min - 1) {
122 oval = ncsn->csn_left->csn_min;
123 ncsn->csn_left = cset_delete(ncsn->csn_left,
124 ncsn->csn_left->csn_min);
125 ncsn->csn_min = oval;
126 }
127 }
128 if (ncsn->csn_right != NULL) {
129 ncsn->csn_right = cset_splay(ncsn->csn_right,
130 ncsn->csn_max + 1);
131 if (ncsn->csn_right->csn_min == ncsn->csn_max + 1) {
132 oval = ncsn->csn_right->csn_max;
133 ncsn->csn_right = cset_delete(ncsn->csn_right,
134 ncsn->csn_right->csn_min);
135 ncsn->csn_max = oval;
136 }
137 }
138
139 return (true);
140 }
141
142 /*
143 * cset_in_hard --
144 * Determine whether a character is in the set without using
145 * the cache.
146 */
147 bool
cset_in_hard(struct cset * cs,wchar_t ch)148 cset_in_hard(struct cset *cs, wchar_t ch)
149 {
150 struct csclass *csc;
151
152 for (csc = cs->cs_classes; csc != NULL; csc = csc->csc_next)
153 if (csc->csc_invert ^ (iswctype(ch, csc->csc_type) != 0))
154 return (cs->cs_invert ^ true);
155 if (cs->cs_root != NULL) {
156 cs->cs_root = cset_splay(cs->cs_root, ch);
157 return (cs->cs_invert ^ (cset_rangecmp(cs->cs_root, ch) == 0));
158 }
159 return (cs->cs_invert ^ false);
160 }
161
162 /*
163 * cset_cache --
164 * Update the cache.
165 */
166 void
cset_cache(struct cset * cs)167 cset_cache(struct cset *cs)
168 {
169 wchar_t i;
170
171 for (i = 0; i < CS_CACHE_SIZE; i++)
172 cs->cs_cache[i] = cset_in_hard(cs, i);
173
174 cs->cs_havecache = true;
175 }
176
177 /*
178 * cset_invert --
179 * Invert the character set.
180 */
181 void
cset_invert(struct cset * cs)182 cset_invert(struct cset *cs)
183 {
184
185 cs->cs_invert ^= true;
186 cs->cs_havecache = false;
187 }
188
189 /*
190 * cset_addclass --
191 * Add a wctype()-style character class to the set, optionally
192 * inverting it.
193 */
194 bool
cset_addclass(struct cset * cs,wctype_t type,bool invert)195 cset_addclass(struct cset *cs, wctype_t type, bool invert)
196 {
197 struct csclass *csc;
198
199 csc = malloc(sizeof (*csc));
200 if (csc == NULL)
201 return (false);
202 csc->csc_type = type;
203 csc->csc_invert = invert;
204 csc->csc_next = cs->cs_classes;
205 cs->cs_classes = csc;
206 cs->cs_havecache = false;
207 return (true);
208 }
209
210 static int
cset_rangecmp(struct csnode * t,wchar_t ch)211 cset_rangecmp(struct csnode *t, wchar_t ch)
212 {
213
214 if (ch < t->csn_min)
215 return (-1);
216 if (ch > t->csn_max)
217 return (1);
218 return (0);
219 }
220
221 static struct csnode *
cset_splay(struct csnode * t,wchar_t ch)222 cset_splay(struct csnode *t, wchar_t ch)
223 {
224 struct csnode N, *l, *r, *y;
225
226 /*
227 * Based on public domain code from Sleator.
228 */
229
230 assert(t != NULL);
231
232 N.csn_left = N.csn_right = NULL;
233 l = r = &N;
234 for (;;) {
235 if (cset_rangecmp(t, ch) < 0) {
236 if (t->csn_left != NULL &&
237 cset_rangecmp(t->csn_left, ch) < 0) {
238 y = t->csn_left;
239 t->csn_left = y->csn_right;
240 y->csn_right = t;
241 t = y;
242 }
243 if (t->csn_left == NULL)
244 break;
245 r->csn_left = t;
246 r = t;
247 t = t->csn_left;
248 } else if (cset_rangecmp(t, ch) > 0) {
249 if (t->csn_right != NULL &&
250 cset_rangecmp(t->csn_right, ch) > 0) {
251 y = t->csn_right;
252 t->csn_right = y->csn_left;
253 y->csn_left = t;
254 t = y;
255 }
256 if (t->csn_right == NULL)
257 break;
258 l->csn_right = t;
259 l = t;
260 t = t->csn_right;
261 } else
262 break;
263 }
264 l->csn_right = t->csn_left;
265 r->csn_left = t->csn_right;
266 t->csn_left = N.csn_right;
267 t->csn_right = N.csn_left;
268 return (t);
269 }
270
271 static struct csnode *
cset_delete(struct csnode * t,wchar_t ch)272 cset_delete(struct csnode *t, wchar_t ch)
273 {
274 struct csnode *x;
275
276 assert(t != NULL);
277 t = cset_splay(t, ch);
278 assert(cset_rangecmp(t, ch) == 0);
279 if (t->csn_left == NULL)
280 x = t->csn_right;
281 else {
282 x = cset_splay(t->csn_left, ch);
283 x->csn_right = t->csn_right;
284 }
285 free(t);
286 return (x);
287 }
288