man_hash.c

   1 /*      $Id: man_hash.c,v 1.31 2015/04/02 22:48:17 schwarze 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 #include "config.h"
  18
  19 #include <sys/types.h>
  20
  21 #include <assert.h>
  22 #include <ctype.h>
  23 #include <limits.h>
  24 #include <string.h>
  25
  26 #include "roff.h"
  27 #include "man.h"
  28 #include "libman.h"
  29
  30 #define HASH_DEPTH       6
  31
  32 #define HASH_ROW(x) do { \
  33                 if (isupper((unsigned char)(x))) \
  34                         (x) -= 65; \
  35                 else \
  36                         (x) -= 97; \
  37                 (x) *= HASH_DEPTH; \
  38         } while (/* CONSTCOND */ 0)
  39
  40 /*
  41  * Lookup table is indexed first by lower-case first letter (plus one
  42  * for the period, which is stored in the last row), then by lower or
  43  * uppercase second letter.  Buckets correspond to the index of the
  44  * macro (the integer value of the enum stored as a char to save a bit
  45  * of space).
  46  */
  47 static  unsigned char    table[26 * HASH_DEPTH];
  48
  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(MAN_MAX < UCHAR_MAX);
  62
  63         for (i = 0; i < (int)MAN_MAX; i++) {
  64                 x = man_macronames[i][0];
  65
  66                 assert(isalpha((unsigned char)x));
  67
  68                 HASH_ROW(x);
  69
  70                 for (j = 0; j < HASH_DEPTH; j++)
  71                         if (UCHAR_MAX == table[x + j]) {
  72                                 table[x + j] = (unsigned char)i;
  73                                 break;
  74                         }
  75
  76                 assert(j < HASH_DEPTH);
  77         }
  78 }
  79
  80 int
  81 man_hash_find(const char *tmp)
  82 {
  83         int              x, y, i;
  84         int              tok;
  85
  86         if ('\0' == (x = tmp[0]))
  87                 return(MAN_MAX);
  88         if ( ! (isalpha((unsigned char)x)))
  89                 return(MAN_MAX);
  90
  91         HASH_ROW(x);
  92
  93         for (i = 0; i < HASH_DEPTH; i++) {
  94                 if (UCHAR_MAX == (y = table[x + i]))
  95                         return(MAN_MAX);
  96
  97                 tok = y;
  98                 if (0 == strcmp(tmp, man_macronames[tok]))
  99                         return(tok);
 100         }
 101
 102         return(MAN_MAX);
 103 }