1/*	$Id: man_hash.c,v 1.25 2011/07/24 18:15:14 kristaps Exp $ */
2/*
3 * Copyright (c) 2008, 2009, 2010 Kristaps Dzonsons <kristaps@bsd.lv>
4 *
5 * Permission to use, copy, modify, and distribute this software for any
6 * purpose with or without fee is hereby granted, provided that the above
7 * copyright notice and this permission notice appear in all copies.
8 *
9 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
12 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
15 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16 */
17#ifdef HAVE_CONFIG_H
18#include "config.h"
19#endif
20
21#include <sys/types.h>
22
23#include <assert.h>
24#include <ctype.h>
25#include <limits.h>
26#include <stdlib.h>
27#include <string.h>
28
29#include "man.h"
30#include "mandoc.h"
31#include "libman.h"
32
33#define	HASH_DEPTH	 6
34
35#define	HASH_ROW(x) do { \
36		if (isupper((unsigned char)(x))) \
37			(x) -= 65; \
38		else \
39			(x) -= 97; \
40		(x) *= HASH_DEPTH; \
41	} while (/* CONSTCOND */ 0)
42
43/*
44 * Lookup table is indexed first by lower-case first letter (plus one
45 * for the period, which is stored in the last row), then by lower or
46 * uppercase second letter.  Buckets correspond to the index of the
47 * macro (the integer value of the enum stored as a char to save a bit
48 * of space).
49 */
50static	unsigned char	 table[26 * HASH_DEPTH];
51
52/*
53 * XXX - this hash has global scope, so if intended for use as a library
54 * with multiple callers, it will need re-invocation protection.
55 */
56void
57man_hash_init(void)
58{
59	int		 i, j, x;
60
61	memset(table, UCHAR_MAX, sizeof(table));
62
63	assert(/* LINTED */
64			MAN_MAX < UCHAR_MAX);
65
66	for (i = 0; i < (int)MAN_MAX; i++) {
67		x = man_macronames[i][0];
68
69		assert(isalpha((unsigned char)x));
70
71		HASH_ROW(x);
72
73		for (j = 0; j < HASH_DEPTH; j++)
74			if (UCHAR_MAX == table[x + j]) {
75				table[x + j] = (unsigned char)i;
76				break;
77			}
78
79		assert(j < HASH_DEPTH);
80	}
81}
82
83
84enum mant
85man_hash_find(const char *tmp)
86{
87	int		 x, y, i;
88	enum mant	 tok;
89
90	if ('\0' == (x = tmp[0]))
91		return(MAN_MAX);
92	if ( ! (isalpha((unsigned char)x)))
93		return(MAN_MAX);
94
95	HASH_ROW(x);
96
97	for (i = 0; i < HASH_DEPTH; i++) {
98		if (UCHAR_MAX == (y = table[x + i]))
99			return(MAN_MAX);
100
101		tok = (enum mant)y;
102		if (0 == strcmp(tmp, man_macronames[tok]))
103			return(tok);
104	}
105
106	return(MAN_MAX);
107}
108