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 * "Character map" ADT. Stores mappings between pairs of characters in a
28 * splay tree, with a lookup table cache to simplify looking up the first
29 * bunch of characters (which are presumably more common than others).
30 */
31
32 #include <assert.h>
33 #include <limits.h>
34 #include <stdbool.h>
35 #include <stdlib.h>
36 #include <wchar.h>
37 #include "cmap.h"
38
39 static struct cmapnode *cmap_splay(struct cmapnode *, wint_t);
40
41 /*
42 * cmap_alloc --
43 * Allocate a character map.
44 */
45 struct cmap *
cmap_alloc(void)46 cmap_alloc(void)
47 {
48 struct cmap *cm;
49
50 cm = malloc(sizeof (*cm));
51 if (cm == NULL)
52 return (NULL);
53 cm->cm_root = NULL;
54 cm->cm_def = CM_DEF_SELF;
55 cm->cm_havecache = false;
56 cm->cm_min = cm->cm_max = 0;
57 return (cm);
58 }
59
60 /*
61 * cmap_add --
62 * Add a mapping from "from" to "to" to the map.
63 */
64 bool
cmap_add(struct cmap * cm,wint_t from,wint_t to)65 cmap_add(struct cmap *cm, wint_t from, wint_t to)
66 {
67 struct cmapnode *cmn, *ncmn;
68
69 cm->cm_havecache = false;
70
71 if (cm->cm_root == NULL) {
72 cmn = malloc(sizeof (*cmn));
73 if (cmn == NULL)
74 return (false);
75 cmn->cmn_from = from;
76 cmn->cmn_to = to;
77 cmn->cmn_left = cmn->cmn_right = NULL;
78 cm->cm_root = cmn;
79 cm->cm_min = cm->cm_max = from;
80 return (true);
81 }
82
83 cmn = cm->cm_root = cmap_splay(cm->cm_root, from);
84
85 if (cmn->cmn_from == from) {
86 cmn->cmn_to = to;
87 return (true);
88 }
89
90 ncmn = malloc(sizeof (*ncmn));
91 if (ncmn == NULL)
92 return (false);
93 ncmn->cmn_from = from;
94 ncmn->cmn_to = to;
95 if (from < cmn->cmn_from) {
96 ncmn->cmn_left = cmn->cmn_left;
97 ncmn->cmn_right = cmn;
98 cmn->cmn_left = NULL;
99 } else {
100 ncmn->cmn_right = cmn->cmn_right;
101 ncmn->cmn_left = cmn;
102 cmn->cmn_right = NULL;
103 }
104 if (from < cm->cm_min)
105 cm->cm_min = from;
106 if (from > cm->cm_max)
107 cm->cm_max = from;
108 cm->cm_root = ncmn;
109
110 return (true);
111 }
112
113 /*
114 * cmap_lookup_hard --
115 * Look up the mapping for a character without using the cache.
116 */
117 wint_t
cmap_lookup_hard(struct cmap * cm,wint_t ch)118 cmap_lookup_hard(struct cmap *cm, wint_t ch)
119 {
120
121 if (cm->cm_root != NULL) {
122 cm->cm_root = cmap_splay(cm->cm_root, ch);
123 if (cm->cm_root->cmn_from == ch)
124 return (cm->cm_root->cmn_to);
125 }
126 return (cm->cm_def == CM_DEF_SELF ? ch : cm->cm_def);
127 }
128
129 /*
130 * cmap_cache --
131 * Update the cache.
132 */
133 void
cmap_cache(struct cmap * cm)134 cmap_cache(struct cmap *cm)
135 {
136 wint_t ch;
137
138 for (ch = 0; ch < CM_CACHE_SIZE; ch++)
139 cm->cm_cache[ch] = cmap_lookup_hard(cm, ch);
140
141 cm->cm_havecache = true;
142 }
143
144 /*
145 * cmap_default --
146 * Change the value that characters without mappings map to, and
147 * return the old value. The special character value CM_MAP_SELF
148 * means characters map to themselves.
149 */
150 wint_t
cmap_default(struct cmap * cm,wint_t def)151 cmap_default(struct cmap *cm, wint_t def)
152 {
153 wint_t old;
154
155 old = cm->cm_def;
156 cm->cm_def = def;
157 cm->cm_havecache = false;
158 return (old);
159 }
160
161 static struct cmapnode *
cmap_splay(struct cmapnode * t,wint_t ch)162 cmap_splay(struct cmapnode *t, wint_t ch)
163 {
164 struct cmapnode N, *l, *r, *y;
165
166 /*
167 * Based on public domain code from Sleator.
168 */
169
170 assert(t != NULL);
171
172 N.cmn_left = N.cmn_right = NULL;
173 l = r = &N;
174 for (;;) {
175 if (ch < t->cmn_from) {
176 if (t->cmn_left != NULL &&
177 ch < t->cmn_left->cmn_from) {
178 y = t->cmn_left;
179 t->cmn_left = y->cmn_right;
180 y->cmn_right = t;
181 t = y;
182 }
183 if (t->cmn_left == NULL)
184 break;
185 r->cmn_left = t;
186 r = t;
187 t = t->cmn_left;
188 } else if (ch > t->cmn_from) {
189 if (t->cmn_right != NULL &&
190 ch > t->cmn_right->cmn_from) {
191 y = t->cmn_right;
192 t->cmn_right = y->cmn_left;
193 y->cmn_left = t;
194 t = y;
195 }
196 if (t->cmn_right == NULL)
197 break;
198 l->cmn_right = t;
199 l = t;
200 t = t->cmn_right;
201 } else
202 break;
203 }
204 l->cmn_right = t->cmn_left;
205 r->cmn_left = t->cmn_right;
206 t->cmn_left = N.cmn_right;
207 t->cmn_right = N.cmn_left;
208 return (t);
209 }
210