1275719Sgshapiro/*-
2275719Sgshapiro * SPDX-License-Identifier: BSD-2-Clause
3275719Sgshapiro *
4275719Sgshapiro * Copyright (c) 2004 Tim J. Robbins.
5275719Sgshapiro * All rights reserved.
6275719Sgshapiro *
7275719Sgshapiro * Redistribution and use in source and binary forms, with or without
8275719Sgshapiro * modification, are permitted provided that the following conditions
9275719Sgshapiro * are met:
10275719Sgshapiro * 1. Redistributions of source code must retain the above copyright
11275719Sgshapiro *    notice, this list of conditions and the following disclaimer.
12275719Sgshapiro * 2. Redistributions in binary form must reproduce the above copyright
13275719Sgshapiro *    notice, this list of conditions and the following disclaimer in the
14275719Sgshapiro *    documentation and/or other materials provided with the distribution.
15275719Sgshapiro *
16275719Sgshapiro * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17275719Sgshapiro * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18275719Sgshapiro * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19275719Sgshapiro * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20275719Sgshapiro * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21275719Sgshapiro * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22275719Sgshapiro * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23275719Sgshapiro * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24275719Sgshapiro * 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#include <assert.h>
36#include <limits.h>
37#include <stdbool.h>
38#include <stdlib.h>
39#include <wchar.h>
40#include "cmap.h"
41
42static struct cmapnode *cmap_splay(struct cmapnode *, wint_t);
43
44/*
45 * cmap_alloc --
46 *	Allocate a character map.
47 */
48struct cmap *
49cmap_alloc(void)
50{
51	struct cmap *cm;
52
53	cm = malloc(sizeof(*cm));
54	if (cm == NULL)
55		return (NULL);
56	cm->cm_root = NULL;
57	cm->cm_def = CM_DEF_SELF;
58	cm->cm_havecache = false;
59	cm->cm_min = cm->cm_max = 0;
60	return (cm);
61}
62
63/*
64 * cmap_add --
65 *	Add a mapping from "from" to "to" to the map.
66 */
67bool
68cmap_add(struct cmap *cm, wint_t from, wint_t to)
69{
70	struct cmapnode *cmn, *ncmn;
71
72	cm->cm_havecache = false;
73
74	if (cm->cm_root == NULL) {
75		cmn = malloc(sizeof(*cmn));
76		if (cmn == NULL)
77			return (false);
78		cmn->cmn_from = from;
79		cmn->cmn_to = to;
80		cmn->cmn_left = cmn->cmn_right = NULL;
81		cm->cm_root = cmn;
82		cm->cm_min = cm->cm_max = from;
83		return (true);
84	}
85
86	cmn = cm->cm_root = cmap_splay(cm->cm_root, from);
87
88	if (cmn->cmn_from == from) {
89		cmn->cmn_to = to;
90		return (true);
91	}
92
93	ncmn = malloc(sizeof(*ncmn));
94	if (ncmn == NULL)
95		return (false);
96	ncmn->cmn_from = from;
97	ncmn->cmn_to = to;
98	if (from < cmn->cmn_from) {
99		ncmn->cmn_left = cmn->cmn_left;
100		ncmn->cmn_right = cmn;
101		cmn->cmn_left = NULL;
102	} else {
103		ncmn->cmn_right = cmn->cmn_right;
104		ncmn->cmn_left = cmn;
105		cmn->cmn_right = NULL;
106	}
107	if (from < cm->cm_min)
108		cm->cm_min = from;
109	if (from > cm->cm_max)
110		cm->cm_max = from;
111        cm->cm_root = ncmn;
112
113	return (true);
114}
115
116/*
117 * cmap_lookup_hard --
118 *	Look up the mapping for a character without using the cache.
119 */
120wint_t
121cmap_lookup_hard(struct cmap *cm, wint_t ch)
122{
123
124	if (cm->cm_root != NULL) {
125		cm->cm_root = cmap_splay(cm->cm_root, ch);
126		if (cm->cm_root->cmn_from == ch)
127			return (cm->cm_root->cmn_to);
128	}
129	return (cm->cm_def == CM_DEF_SELF ? ch : cm->cm_def);
130}
131
132/*
133 * cmap_cache --
134 *	Update the cache.
135 */
136void
137cmap_cache(struct cmap *cm)
138{
139	wint_t ch;
140
141	for (ch = 0; ch < CM_CACHE_SIZE; ch++)
142		cm->cm_cache[ch] = cmap_lookup_hard(cm, ch);
143
144	cm->cm_havecache = true;
145}
146
147/*
148 * cmap_default --
149 *	Change the value that characters without mappings map to, and
150 *	return the old value. The special character value CM_MAP_SELF
151 *	means characters map to themselves.
152 */
153wint_t
154cmap_default(struct cmap *cm, wint_t def)
155{
156	wint_t old;
157
158	old = cm->cm_def;
159	cm->cm_def = def;
160	cm->cm_havecache = false;
161	return (old);
162}
163
164static struct cmapnode *
165cmap_splay(struct cmapnode *t, wint_t ch)
166{
167	struct cmapnode N, *l, *r, *y;
168
169	/*
170	 * Based on public domain code from Sleator.
171	 */
172
173	assert(t != NULL);
174
175	N.cmn_left = N.cmn_right = NULL;
176	l = r = &N;
177	for (;;) {
178		if (ch < t->cmn_from) {
179			if (t->cmn_left != NULL &&
180			    ch < t->cmn_left->cmn_from) {
181				y = t->cmn_left;
182				t->cmn_left = y->cmn_right;
183				y->cmn_right = t;
184				t = y;
185			}
186			if (t->cmn_left == NULL)
187				break;
188			r->cmn_left = t;
189			r = t;
190			t = t->cmn_left;
191		} else if (ch > t->cmn_from) {
192			if (t->cmn_right != NULL &&
193			    ch > t->cmn_right->cmn_from) {
194				y = t->cmn_right;
195				t->cmn_right = y->cmn_left;
196				y->cmn_left = t;
197				t = y;
198			}
199			if (t->cmn_right == NULL)
200				break;
201			l->cmn_right = t;
202			l = t;
203			t = t->cmn_right;
204		} else
205			break;
206	}
207	l->cmn_right = t->cmn_left;
208	r->cmn_left = t->cmn_right;
209	t->cmn_left = N.cmn_right;
210	t->cmn_right = N.cmn_left;
211	return (t);
212}
213