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 * $FreeBSD: head/usr.bin/tr/cmap.c 200462 2009-12-13 03:14:06Z delphij $
27 */
28 /*
29 * "Character map" ADT. Stores mappings between pairs of characters in a
30 * splay tree, with a lookup table cache to simplify looking up the first
31 * bunch of characters (which are presumably more common than others).
32 */
33
34 #include <assert.h>
35 #include <limits.h>
36 #include <stdbool.h>
37 #include <stdlib.h>
38 #include <wchar.h>
39 #include "cmap.h"
40
41 static struct cmapnode *cmap_splay(struct cmapnode *, wint_t);
42
43 /*
44 * cmap_alloc --
45 * Allocate a character map.
46 */
47 struct cmap *
cmap_alloc(void)48 cmap_alloc(void)
49 {
50 struct cmap *cm;
51
52 cm = malloc(sizeof(*cm));
53 if (cm == NULL)
54 return (NULL);
55 cm->cm_root = NULL;
56 cm->cm_def = CM_DEF_SELF;
57 cm->cm_havecache = false;
58 cm->cm_min = cm->cm_max = 0;
59 return (cm);
60 }
61
62 /*
63 * cmap_add --
64 * Add a mapping from "from" to "to" to the map.
65 */
66 bool
cmap_add(struct cmap * cm,wint_t from,wint_t to)67 cmap_add(struct cmap *cm, wint_t from, wint_t to)
68 {
69 struct cmapnode *cmn, *ncmn;
70
71 cm->cm_havecache = false;
72
73 if (cm->cm_root == NULL) {
74 cmn = malloc(sizeof(*cmn));
75 if (cmn == NULL)
76 return (false);
77 cmn->cmn_from = from;
78 cmn->cmn_to = to;
79 cmn->cmn_left = cmn->cmn_right = NULL;
80 cm->cm_root = cmn;
81 cm->cm_min = cm->cm_max = from;
82 return (true);
83 }
84
85 cmn = cm->cm_root = cmap_splay(cm->cm_root, from);
86
87 if (cmn->cmn_from == from) {
88 cmn->cmn_to = to;
89 return (true);
90 }
91
92 ncmn = malloc(sizeof(*ncmn));
93 if (ncmn == NULL)
94 return (false);
95 ncmn->cmn_from = from;
96 ncmn->cmn_to = to;
97 if (from < cmn->cmn_from) {
98 ncmn->cmn_left = cmn->cmn_left;
99 ncmn->cmn_right = cmn;
100 cmn->cmn_left = NULL;
101 } else {
102 ncmn->cmn_right = cmn->cmn_right;
103 ncmn->cmn_left = cmn;
104 cmn->cmn_right = NULL;
105 }
106 if (from < cm->cm_min)
107 cm->cm_min = from;
108 if (from > cm->cm_max)
109 cm->cm_max = from;
110 cm->cm_root = ncmn;
111
112 return (true);
113 }
114
115 /*
116 * cmap_lookup_hard --
117 * Look up the mapping for a character without using the cache.
118 */
119 wint_t
cmap_lookup_hard(struct cmap * cm,wint_t ch)120 cmap_lookup_hard(struct cmap *cm, wint_t ch)
121 {
122
123 if (cm->cm_root != NULL) {
124 cm->cm_root = cmap_splay(cm->cm_root, ch);
125 if (cm->cm_root->cmn_from == ch)
126 return (cm->cm_root->cmn_to);
127 }
128 return (cm->cm_def == CM_DEF_SELF ? ch : cm->cm_def);
129 }
130
131 /*
132 * cmap_cache --
133 * Update the cache.
134 */
135 void
cmap_cache(struct cmap * cm)136 cmap_cache(struct cmap *cm)
137 {
138 wint_t ch;
139
140 for (ch = 0; ch < CM_CACHE_SIZE; ch++)
141 cm->cm_cache[ch] = cmap_lookup_hard(cm, ch);
142
143 cm->cm_havecache = true;
144 }
145
146 /*
147 * cmap_default --
148 * Change the value that characters without mappings map to, and
149 * return the old value. The special character value CM_MAP_SELF
150 * means characters map to themselves.
151 */
152 wint_t
cmap_default(struct cmap * cm,wint_t def)153 cmap_default(struct cmap *cm, wint_t def)
154 {
155 wint_t old;
156
157 old = cm->cm_def;
158 cm->cm_def = def;
159 cm->cm_havecache = false;
160 return (old);
161 }
162
163 static struct cmapnode *
cmap_splay(struct cmapnode * t,wint_t ch)164 cmap_splay(struct cmapnode *t, wint_t ch)
165 {
166 struct cmapnode N, *l, *r, *y;
167
168 /*
169 * Based on public domain code from Sleator.
170 */
171
172 assert(t != NULL);
173
174 N.cmn_left = N.cmn_right = NULL;
175 l = r = &N;
176 for (;;) {
177 if (ch < t->cmn_from) {
178 if (t->cmn_left != NULL &&
179 ch < t->cmn_left->cmn_from) {
180 y = t->cmn_left;
181 t->cmn_left = y->cmn_right;
182 y->cmn_right = t;
183 t = y;
184 }
185 if (t->cmn_left == NULL)
186 break;
187 r->cmn_left = t;
188 r = t;
189 t = t->cmn_left;
190 } else if (ch > t->cmn_from) {
191 if (t->cmn_right != NULL &&
192 ch > t->cmn_right->cmn_from) {
193 y = t->cmn_right;
194 t->cmn_right = y->cmn_left;
195 y->cmn_left = t;
196 t = y;
197 }
198 if (t->cmn_right == NULL)
199 break;
200 l->cmn_right = t;
201 l = t;
202 t = t->cmn_right;
203 } else
204 break;
205 }
206 l->cmn_right = t->cmn_left;
207 r->cmn_left = t->cmn_right;
208 t->cmn_left = N.cmn_right;
209 t->cmn_right = N.cmn_left;
210 return (t);
211 }
212