1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD 3 * 4 * Copyright (c) 2004 Tim J. Robbins. 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26 * SUCH DAMAGE. 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 <sys/cdefs.h> 35 __FBSDID("$FreeBSD$"); 36 37 #include <assert.h> 38 #include <limits.h> 39 #include <stdbool.h> 40 #include <stdlib.h> 41 #include <wchar.h> 42 #include "cmap.h" 43 44 static struct cmapnode *cmap_splay(struct cmapnode *, wint_t); 45 46 /* 47 * cmap_alloc -- 48 * Allocate a character map. 49 */ 50 struct cmap * 51 cmap_alloc(void) 52 { 53 struct cmap *cm; 54 55 cm = malloc(sizeof(*cm)); 56 if (cm == NULL) 57 return (NULL); 58 cm->cm_root = NULL; 59 cm->cm_def = CM_DEF_SELF; 60 cm->cm_havecache = false; 61 cm->cm_min = cm->cm_max = 0; 62 return (cm); 63 } 64 65 /* 66 * cmap_add -- 67 * Add a mapping from "from" to "to" to the map. 68 */ 69 bool 70 cmap_add(struct cmap *cm, wint_t from, wint_t to) 71 { 72 struct cmapnode *cmn, *ncmn; 73 74 cm->cm_havecache = false; 75 76 if (cm->cm_root == NULL) { 77 cmn = malloc(sizeof(*cmn)); 78 if (cmn == NULL) 79 return (false); 80 cmn->cmn_from = from; 81 cmn->cmn_to = to; 82 cmn->cmn_left = cmn->cmn_right = NULL; 83 cm->cm_root = cmn; 84 cm->cm_min = cm->cm_max = from; 85 return (true); 86 } 87 88 cmn = cm->cm_root = cmap_splay(cm->cm_root, from); 89 90 if (cmn->cmn_from == from) { 91 cmn->cmn_to = to; 92 return (true); 93 } 94 95 ncmn = malloc(sizeof(*ncmn)); 96 if (ncmn == NULL) 97 return (false); 98 ncmn->cmn_from = from; 99 ncmn->cmn_to = to; 100 if (from < cmn->cmn_from) { 101 ncmn->cmn_left = cmn->cmn_left; 102 ncmn->cmn_right = cmn; 103 cmn->cmn_left = NULL; 104 } else { 105 ncmn->cmn_right = cmn->cmn_right; 106 ncmn->cmn_left = cmn; 107 cmn->cmn_right = NULL; 108 } 109 if (from < cm->cm_min) 110 cm->cm_min = from; 111 if (from > cm->cm_max) 112 cm->cm_max = from; 113 cm->cm_root = ncmn; 114 115 return (true); 116 } 117 118 /* 119 * cmap_lookup_hard -- 120 * Look up the mapping for a character without using the cache. 121 */ 122 wint_t 123 cmap_lookup_hard(struct cmap *cm, wint_t ch) 124 { 125 126 if (cm->cm_root != NULL) { 127 cm->cm_root = cmap_splay(cm->cm_root, ch); 128 if (cm->cm_root->cmn_from == ch) 129 return (cm->cm_root->cmn_to); 130 } 131 return (cm->cm_def == CM_DEF_SELF ? ch : cm->cm_def); 132 } 133 134 /* 135 * cmap_cache -- 136 * Update the cache. 137 */ 138 void 139 cmap_cache(struct cmap *cm) 140 { 141 wint_t ch; 142 143 for (ch = 0; ch < CM_CACHE_SIZE; ch++) 144 cm->cm_cache[ch] = cmap_lookup_hard(cm, ch); 145 146 cm->cm_havecache = true; 147 } 148 149 /* 150 * cmap_default -- 151 * Change the value that characters without mappings map to, and 152 * return the old value. The special character value CM_MAP_SELF 153 * means characters map to themselves. 154 */ 155 wint_t 156 cmap_default(struct cmap *cm, wint_t def) 157 { 158 wint_t old; 159 160 old = cm->cm_def; 161 cm->cm_def = def; 162 cm->cm_havecache = false; 163 return (old); 164 } 165 166 static struct cmapnode * 167 cmap_splay(struct cmapnode *t, wint_t ch) 168 { 169 struct cmapnode N, *l, *r, *y; 170 171 /* 172 * Based on public domain code from Sleator. 173 */ 174 175 assert(t != NULL); 176 177 N.cmn_left = N.cmn_right = NULL; 178 l = r = &N; 179 for (;;) { 180 if (ch < t->cmn_from) { 181 if (t->cmn_left != NULL && 182 ch < t->cmn_left->cmn_from) { 183 y = t->cmn_left; 184 t->cmn_left = y->cmn_right; 185 y->cmn_right = t; 186 t = y; 187 } 188 if (t->cmn_left == NULL) 189 break; 190 r->cmn_left = t; 191 r = t; 192 t = t->cmn_left; 193 } else if (ch > t->cmn_from) { 194 if (t->cmn_right != NULL && 195 ch > t->cmn_right->cmn_from) { 196 y = t->cmn_right; 197 t->cmn_right = y->cmn_left; 198 y->cmn_left = t; 199 t = y; 200 } 201 if (t->cmn_right == NULL) 202 break; 203 l->cmn_right = t; 204 l = t; 205 t = t->cmn_right; 206 } else 207 break; 208 } 209 l->cmn_right = t->cmn_left; 210 r->cmn_left = t->cmn_right; 211 t->cmn_left = N.cmn_right; 212 t->cmn_right = N.cmn_left; 213 return (t); 214 } 215