man_hash.c

   1 /*      $Id: man_hash.c,v 1.20 2010/05/15 22:49:58 kristaps Exp $ */
   2 /*
   3  * Copyright (c) 2008, 2009 Kristaps Dzonsons <kristaps@kth.se>
   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 "libman.h"
  30
  31 #define HASH_DEPTH       6
  32
  33 #define HASH_ROW(x) do { \
  34                 if (isupper((u_char)(x))) \
  35                         (x) -= 65; \
  36                 else \
  37                         (x) -= 97; \
  38                 (x) *= HASH_DEPTH; \
  39         } while (/* CONSTCOND */ 0)
  40
  41 /*
  42  * Lookup table is indexed first by lower-case first letter (plus one
  43  * for the period, which is stored in the last row), then by lower or
  44  * uppercase second letter.  Buckets correspond to the index of the
  45  * macro (the integer value of the enum stored as a char to save a bit
  46  * of space).
  47  */
  48 static  u_char           table[26 * HASH_DEPTH];
  49
  50 /*
  51  * XXX - this hash has global scope, so if intended for use as a library
  52  * with multiple callers, it will need re-invocation protection.
  53  */
  54 void
  55 man_hash_init(void)
  56 {
  57         int              i, j, x;
  58
  59         memset(table, UCHAR_MAX, sizeof(table));
  60
  61         assert(/* LINTED */
  62                         MAN_MAX < UCHAR_MAX);
  63
  64         for (i = 0; i < (int)MAN_MAX; i++) {
  65                 x = man_macronames[i][0];
  66
  67                 assert(isalpha((u_char)x));
  68
  69                 HASH_ROW(x);
  70
  71                 for (j = 0; j < HASH_DEPTH; j++)
  72                         if (UCHAR_MAX == table[x + j]) {
  73                                 table[x + j] = (u_char)i;
  74                                 break;
  75                         }
  76
  77                 assert(j < HASH_DEPTH);
  78         }
  79 }
  80
  81
  82 enum mant
  83 man_hash_find(const char *tmp)
  84 {
  85         int              x, y, i;
  86         enum mant        tok;
  87
  88         if ('\0' == (x = tmp[0]))
  89                 return(MAN_MAX);
  90         if ( ! (isalpha((u_char)x)))
  91                 return(MAN_MAX);
  92
  93         HASH_ROW(x);
  94
  95         for (i = 0; i < HASH_DEPTH; i++) {
  96                 if (UCHAR_MAX == (y = table[x + i]))
  97                         return(MAN_MAX);
  98
  99                 tok = (enum mant)y;
 100                 if (0 == strcmp(tmp, man_macronames[tok]))
 101                         return(tok);
 102         }
 103
 104         return(MAN_MAX);
 105 }