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255 lines
7.1 KiB
C
255 lines
7.1 KiB
C
/* Copyright (C) 1995,1996,1997, 2000 Free Software Foundation, Inc.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2, or (at your option)
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* any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this software; see the file COPYING. If not, write to
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* the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
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* Boston, MA 02111-1307 USA
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*
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* As a special exception, the Free Software Foundation gives permission
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* for additional uses of the text contained in its release of GUILE.
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*
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* The exception is that, if you link the GUILE library with other files
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* to produce an executable, this does not by itself cause the
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* resulting executable to be covered by the GNU General Public License.
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* Your use of that executable is in no way restricted on account of
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* linking the GUILE library code into it.
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*
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* This exception does not however invalidate any other reasons why
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* the executable file might be covered by the GNU General Public License.
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*
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* This exception applies only to the code released by the
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* Free Software Foundation under the name GUILE. If you copy
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* code from other Free Software Foundation releases into a copy of
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* GUILE, as the General Public License permits, the exception does
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* not apply to the code that you add in this way. To avoid misleading
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* anyone as to the status of such modified files, you must delete
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* this exception notice from them.
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*
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* If you write modifications of your own for GUILE, it is your choice
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* whether to permit this exception to apply to your modifications.
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* If you do not wish that, delete this exception notice. */
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/* Software engineering face-lift by Greg J. Badros, 11-Dec-1999,
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gjb@cs.washington.edu, http://www.cs.washington.edu/homes/gjb */
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#include <stdio.h>
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#include "_scm.h"
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#include "chars.h"
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#include "ports.h"
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#include "vectors.h"
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#include "validate.h"
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#include "hash.h"
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#ifndef floor
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extern double floor();
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#endif
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unsigned long
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scm_hasher(SCM obj, unsigned long n, scm_sizet d)
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{
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switch (7 & (int) obj) {
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case 2:
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case 6:
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return SCM_INUM(obj) % n; /* SCM_INUMP(obj) */
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case 4:
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if SCM_CHARP(obj)
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return (unsigned)(scm_downcase(SCM_CHAR(obj))) % n;
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switch ((int) obj) {
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#ifndef SICP
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case (int) SCM_EOL:
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d = 256;
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break;
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#endif
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case (int) SCM_BOOL_T:
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d = 257;
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break;
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case (int) SCM_BOOL_F:
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d = 258;
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break;
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case (int) SCM_EOF_VAL:
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d = 259;
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break;
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default:
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d = 263; /* perhaps should be error */
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}
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return d % n;
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default:
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return 263 % n; /* perhaps should be error */
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case 0:
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switch SCM_TYP7(obj) {
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default:
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return 263 % n;
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case scm_tc7_smob:
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switch SCM_TYP16(obj) {
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case scm_tc16_big:
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return SCM_INUM(scm_modulo(obj, SCM_MAKINUM(n)));
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default:
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return 263 % n;
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case scm_tc16_real:
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{
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double r = SCM_REALPART(obj);
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if (floor(r)==r) {
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obj = scm_inexact_to_exact (obj);
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if SCM_IMP(obj) return SCM_INUM(obj) % n;
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return SCM_INUM(scm_modulo(obj, SCM_MAKINUM(n)));
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}
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}
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case scm_tc16_complex:
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obj = scm_number_to_string(obj, SCM_MAKINUM(10));
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}
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case scm_tcs_symbols:
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case scm_tc7_string:
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case scm_tc7_substring:
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return scm_strhash(SCM_ROUCHARS(obj), (scm_sizet) SCM_ROLENGTH(obj), n);
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case scm_tc7_wvect:
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case scm_tc7_vector:
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{
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scm_sizet len = SCM_LENGTH(obj);
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SCM *data = SCM_VELTS(obj);
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if (len>5)
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{
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scm_sizet i = d/2;
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unsigned long h = 1;
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while (i--) h = ((h<<8) + (scm_hasher(data[h % len], n, 2))) % n;
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return h;
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}
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else
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{
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scm_sizet i = len;
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unsigned long h = (n)-1;
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while (i--) h = ((h<<8) + (scm_hasher(data[i], n, d/len))) % n;
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return h;
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}
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}
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case scm_tcs_cons_imcar:
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case scm_tcs_cons_nimcar:
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if (d) return (scm_hasher(SCM_CAR(obj), n, d/2)+scm_hasher(SCM_CDR(obj), n, d/2)) % n;
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else return 1;
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case scm_tc7_port:
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return ((SCM_RDNG & SCM_UNPACK_CAR(obj)) ? 260 : 261) % n;
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case scm_tcs_closures:
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case scm_tc7_contin:
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case scm_tcs_subrs:
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return 262 % n;
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}
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}
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}
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unsigned int
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scm_ihashq (SCM obj, unsigned int n)
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{
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return (((unsigned int) obj) >> 1) % n;
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}
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SCM_DEFINE (scm_hashq, "hashq", 2, 0, 0,
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(SCM key, SCM size),
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"Determine a hash value for KEY that is suitable for lookups in\n"
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"a hashtable of size SIZE, where eq? is used as the equality\n"
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"predicate. The function returns an integer in the range 0 to\n"
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"SIZE - 1. NOTE that `hashq' may use internal addresses.\n"
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"Thus two calls to hashq where the keys are eq? are not\n"
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"guaranteed to deliver the same value if the key object gets\n"
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"garbage collected in between. This can happen, for example\n"
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"with symbols: (hashq 'foo n) (gc) (hashq 'foo n) may produce two\n"
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"different values, since 'foo will be garbage collected.")
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#define FUNC_NAME s_scm_hashq
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{
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SCM_VALIDATE_INUM_MIN (2, size, 0);
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return SCM_MAKINUM (scm_ihashq (key, SCM_INUM (size)));
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}
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#undef FUNC_NAME
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unsigned int
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scm_ihashv (SCM obj, unsigned int n)
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{
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if (SCM_CHARP(obj))
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return ((unsigned int)(scm_downcase(SCM_CHAR(obj)))) % n; /* downcase!?!! */
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if (SCM_NUMP(obj))
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return (unsigned int) scm_hasher(obj, n, 10);
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else
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return ((unsigned int)obj) % n;
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}
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SCM_DEFINE (scm_hashv, "hashv", 2, 0, 0,
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(SCM key, SCM size),
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"Determine a hash value for KEY that is suitable for lookups in\n"
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"a hashtable of size SIZE, where eqv? is used as the equality\n"
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"predicate. The function returns an integer in the range 0 to\n"
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"SIZE - 1. NOTE that (hashv key) may use internal addresses.\n"
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"Thus two calls to hashv where the keys are eqv? are not\n"
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"guaranteed to deliver the same value if the key object gets\n"
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"garbage collected in between. This can happen, for example\n"
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"with symbols: (hashv 'foo n) (gc) (hashv 'foo n) may produce two\n"
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"different values, since 'foo will be garbage collected.")
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#define FUNC_NAME s_scm_hashv
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{
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SCM_VALIDATE_INUM_MIN (2, size, 0);
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return SCM_MAKINUM (scm_ihashv (key, SCM_INUM (size)));
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}
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#undef FUNC_NAME
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unsigned int
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scm_ihash (SCM obj, unsigned int n)
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{
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return (unsigned int)scm_hasher (obj, n, 10);
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}
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SCM_DEFINE (scm_hash, "hash", 2, 0, 0,
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(SCM key, SCM size),
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"Determine a hash value for KEY that is suitable for lookups in\n"
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"a hashtable of size SIZE, where equal? is used as the equality\n"
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"predicate. The function returns an integer in the range 0 to\n"
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"SIZE - 1.")
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#define FUNC_NAME s_scm_hash
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{
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SCM_VALIDATE_INUM_MIN (2, size, 0);
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return SCM_MAKINUM (scm_ihash (key, SCM_INUM (size)));
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}
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#undef FUNC_NAME
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void
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scm_init_hash ()
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{
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#include "hash.x"
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}
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/*
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Local Variables:
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c-file-style: "gnu"
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End:
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*/
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