libguile/hash.c

   1 /*      Copyright (C) 1995,1996,1997 Free Software Foundation, Inc.
   2  *
   3  * This program is free software; you can redistribute it and/or modify
   4  * it under the terms of the GNU General Public License as published by
   5  * the Free Software Foundation; either version 2, or (at your option)
   6  * any later version.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11  * GNU General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public License
  14  * along with this software; see the file COPYING.  If not, write to
  15  * the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
  16  * Boston, MA 02111-1307 USA
  17  *
  18  * As a special exception, the Free Software Foundation gives permission
  19  * for additional uses of the text contained in its release of GUILE.
  20  *
  21  * The exception is that, if you link the GUILE library with other files
  22  * to produce an executable, this does not by itself cause the
  23  * resulting executable to be covered by the GNU General Public License.
  24  * Your use of that executable is in no way restricted on account of
  25  * linking the GUILE library code into it.
  26  *
  27  * This exception does not however invalidate any other reasons why
  28  * the executable file might be covered by the GNU General Public License.
  29  *
  30  * This exception applies only to the code released by the
  31  * Free Software Foundation under the name GUILE.  If you copy
  32  * code from other Free Software Foundation releases into a copy of
  33  * GUILE, as the General Public License permits, the exception does
  34  * not apply to the code that you add in this way.  To avoid misleading
  35  * anyone as to the status of such modified files, you must delete
  36  * this exception notice from them.
  37  *
  38  * If you write modifications of your own for GUILE, it is your choice
  39  * whether to permit this exception to apply to your modifications.
  40  * If you do not wish that, delete this exception notice.  */
  41
  42 /* Software engineering face-lift by Greg J. Badros, 11-Dec-1999,
  43    gjb@cs.washington.edu, http://www.cs.washington.edu/homes/gjb */
  44
  45 \f
  46
  47 #include <stdio.h>
  48 #include "_scm.h"
  49 #include "chars.h"
  50
  51 #include "scm_validate.h"
  52 #include "hash.h"
  53 \f
  54
  55 #ifndef floor
  56 extern double floor();
  57 #endif
  58
  59
  60 unsigned long
  61 scm_hasher(SCM obj, unsigned long n, scm_sizet d)
  62 {
  63   switch (7 & (int) obj) {
  64   case 2: case 6:               /* SCM_INUMP(obj) */
  65     return SCM_INUM(obj) % n;
  66   case 4:
  67     if SCM_ICHRP(obj)
  68       return (unsigned)(scm_downcase(SCM_ICHR(obj))) % n;
  69     switch ((int) obj) {
  70 #ifndef SICP
  71     case (int) SCM_EOL: d = 256; break;
  72 #endif
  73     case (int) SCM_BOOL_T: d = 257; break;
  74     case (int) SCM_BOOL_F: d = 258; break;
  75     case (int) SCM_EOF_VAL: d = 259; break;
  76     default: d = 263;           /* perhaps should be error */
  77     }
  78     return d % n;
  79   default: return 263 % n;      /* perhaps should be error */
  80   case 0:
  81     switch SCM_TYP7(obj) {
  82     default: return 263 % n;
  83     case scm_tc7_smob:
  84       switch SCM_TYP16(obj) {
  85       case scm_tcs_bignums:
  86       bighash: return SCM_INUM(scm_modulo(obj, SCM_MAKINUM(n)));
  87       default: return 263 % n;
  88 #ifdef SCM_FLOATS
  89       case scm_tc16_flo:
  90         if SCM_REALP(obj) {
  91           double r = SCM_REALPART(obj);
  92           if (floor(r)==r) {
  93             obj = scm_inexact_to_exact (obj);
  94             if SCM_IMP(obj) return SCM_INUM(obj) % n;
  95             goto bighash;
  96           }
  97         }
  98         obj = scm_number_to_string(obj, SCM_MAKINUM(10));
  99 #endif
 100       }
 101     case scm_tcs_symbols:
 102     case scm_tc7_string:
 103     case scm_tc7_substring:
 104       return scm_strhash(SCM_ROUCHARS(obj), (scm_sizet) SCM_ROLENGTH(obj), n);
 105     case scm_tc7_wvect:
 106     case scm_tc7_vector:
 107       {
 108         scm_sizet len = SCM_LENGTH(obj);
 109         SCM *data = SCM_VELTS(obj);
 110         if (len>5)
 111           {
 112             scm_sizet i = d/2;
 113             unsigned long h = 1;
 114             while (i--) h = ((h<<8) + (scm_hasher(data[h % len], n, 2))) % n;
 115             return h;
 116           }
 117         else
 118           {
 119             scm_sizet i = len;
 120             unsigned long h = (n)-1;
 121             while (i--) h = ((h<<8) + (scm_hasher(data[i], n, d/len))) % n;
 122             return h;
 123           }
 124       }
 125     case scm_tcs_cons_imcar: case scm_tcs_cons_nimcar:
 126       if (d) return (scm_hasher(SCM_CAR(obj), n, d/2)+scm_hasher(SCM_CDR(obj), n, d/2)) % n;
 127       else return 1;
 128     case scm_tc7_port:
 129       return ((SCM_RDNG & SCM_CAR(obj)) ? 260 : 261) % n;
 130     case scm_tcs_closures: case scm_tc7_contin: case scm_tcs_subrs:
 131       return 262 % n;
 132     }
 133   }
 134 }
 135
 136
 137 \f
 138
 139
 140 unsigned int
 141 scm_ihashq (SCM obj, unsigned int n)
 142 {
 143   return (((unsigned int) obj) >> 1) % n;
 144 }
 145
 146
 147 SCM_DEFINE (scm_hashq, "hashq", 2, 0, 0,
 148            (SCM obj, SCM n),
 149 "@deffnx primitive hashv key size
 150 @deffnx primitive hash key size
 151 Default hash functions for Guile hash tables.  @var{key} is the
 152 object to be hashed, and @var{size} is the size of the target hash
 153 table.  Each function returns an integer in the range 0 to
 154 @var{size}-1.")
 155 #define FUNC_NAME s_scm_hashq
 156 {
 157   SCM_VALIDATE_INUM_MIN (2,n,0);
 158   return SCM_MAKINUM(scm_ihashq (obj, SCM_INUM (n)));
 159 }
 160 #undef FUNC_NAME
 161
 162
 163 \f
 164
 165
 166 unsigned int
 167 scm_ihashv (SCM obj, unsigned int n)
 168 {
 169   if (SCM_ICHRP(obj))
 170     return ((unsigned int)(scm_downcase(SCM_ICHR(obj)))) % n; /* downcase!?!! */
 171
 172   if (SCM_NUMP(obj))
 173     return (unsigned int) scm_hasher(obj, n, 10);
 174   else
 175     return ((unsigned int)obj) % n;
 176 }
 177
 178
 179 SCM_DEFINE (scm_hashv, "hashv", 2, 0, 0,
 180            (SCM obj, SCM n),
 181 "")
 182 #define FUNC_NAME s_scm_hashv
 183 {
 184   SCM_VALIDATE_INUM_MIN (2,n,0);
 185   return SCM_MAKINUM(scm_ihashv (obj, SCM_INUM (n)));
 186 }
 187 #undef FUNC_NAME
 188
 189
 190 \f
 191
 192
 193 unsigned int
 194 scm_ihash (SCM obj, unsigned int n)
 195 {
 196   return (unsigned int)scm_hasher (obj, n, 10);
 197 }
 198
 199 SCM_DEFINE (scm_hash, "hash", 2, 0, 0,
 200            (SCM obj, SCM n),
 201 "")
 202 #define FUNC_NAME s_scm_hash
 203 {
 204   SCM_VALIDATE_INUM_MIN (2,n,0);
 205   return SCM_MAKINUM(scm_ihash(obj, SCM_INUM(n)));
 206 }
 207 #undef FUNC_NAME
 208
 209
 210 \f
 211
 212
 213 void
 214 scm_init_hash ()
 215 {
 216 #include "hash.x"
 217 }
 218