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https://git.savannah.gnu.org/git/guile.git
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266 lines
6.9 KiB
C
266 lines
6.9 KiB
C
/* Copyright (C) 1995,1996,1997, 2000, 2001, 2003, 2004, 2006 Free Software Foundation, Inc.
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library 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 GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include "libguile/_scm.h"
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#include "libguile/chars.h"
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#include "libguile/ports.h"
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#include "libguile/strings.h"
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#include "libguile/symbols.h"
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#include "libguile/vectors.h"
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#include "libguile/validate.h"
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#include "libguile/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_string_hash (const unsigned char *str, size_t len)
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{
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/* from suggestion at: */
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/* http://srfi.schemers.org/srfi-13/mail-archive/msg00112.html */
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unsigned long h = 0;
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while (len-- > 0)
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h = *str++ + h*37;
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return h;
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}
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/* Dirk:FIXME:: why downcase for characters? (2x: scm_hasher, scm_ihashv) */
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/* Dirk:FIXME:: scm_hasher could be made static. */
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unsigned long
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scm_hasher(SCM obj, unsigned long n, size_t d)
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{
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switch (SCM_ITAG3 (obj)) {
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case scm_tc3_int_1:
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case scm_tc3_int_2:
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return SCM_I_INUM(obj) % n; /* SCM_INUMP(obj) */
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case scm_tc3_imm24:
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if (SCM_CHARP(obj))
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return (unsigned)(scm_c_downcase(SCM_CHAR(obj))) % n;
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switch (SCM_UNPACK (obj)) {
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#ifndef SICP
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case SCM_UNPACK(SCM_EOL):
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d = 256;
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break;
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#endif
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case SCM_UNPACK(SCM_BOOL_T):
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d = 257;
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break;
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case SCM_UNPACK(SCM_BOOL_F):
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d = 258;
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break;
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case SCM_UNPACK(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 scm_tc3_cons:
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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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return 263 % n;
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case scm_tc7_number:
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switch SCM_TYP16 (obj) {
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case scm_tc16_big:
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return scm_to_ulong (scm_modulo (obj, scm_from_ulong (n)));
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case scm_tc16_real:
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{
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double r = SCM_REAL_VALUE (obj);
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if (floor (r) == r)
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{
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obj = scm_inexact_to_exact (obj);
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return scm_to_ulong (scm_modulo (obj, scm_from_ulong (n)));
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}
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}
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/* Fall through */
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case scm_tc16_complex:
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case scm_tc16_fraction:
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obj = scm_number_to_string (obj, scm_from_int (10));
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/* Fall through */
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}
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/* Fall through */
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case scm_tc7_string:
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{
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unsigned long hash =
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scm_string_hash ((const unsigned char *) scm_i_string_chars (obj),
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scm_i_string_length (obj)) % n;
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scm_remember_upto_here_1 (obj);
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return hash;
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}
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case scm_tc7_symbol:
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return scm_i_symbol_hash (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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size_t len = SCM_SIMPLE_VECTOR_LENGTH (obj);
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if (len > 5)
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{
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size_t i = d/2;
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unsigned long h = 1;
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while (i--)
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{
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SCM elt = SCM_SIMPLE_VECTOR_REF (obj, h % len);
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h = ((h << 8) + (scm_hasher (elt, n, 2))) % n;
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}
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return h;
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}
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else
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{
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size_t i = len;
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unsigned long h = (n)-1;
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while (i--)
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{
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SCM elt = SCM_SIMPLE_VECTOR_REF (obj, h % len);
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h = ((h << 8) + (scm_hasher (elt, n, d/len))) % n;
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}
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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)
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+ 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_CELL_WORD_0 (obj)) ? 260 : 261) % n;
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case scm_tcs_closures:
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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 long
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scm_ihashq (SCM obj, unsigned long n)
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{
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return (SCM_UNPACK (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 @var{key} that is suitable for\n"
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"lookups in a hashtable of size @var{size}, where @code{eq?} is\n"
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"used as the equality predicate. The function returns an\n"
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"integer in the range 0 to @var{size} - 1. Note that\n"
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"@code{hashq} may use internal addresses. Thus two calls to\n"
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"hashq where the keys are @code{eq?} are not guaranteed to\n"
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"deliver the same value if the key object gets garbage collected\n"
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"in between. This can happen, for example with symbols:\n"
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"@code{(hashq 'foo n) (gc) (hashq 'foo n)} may produce two\n"
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"different values, since @code{foo} will be garbage collected.")
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#define FUNC_NAME s_scm_hashq
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{
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unsigned long sz = scm_to_unsigned_integer (size, 1, ULONG_MAX);
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return scm_from_ulong (scm_ihashq (key, sz));
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}
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#undef FUNC_NAME
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unsigned long
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scm_ihashv (SCM obj, unsigned long n)
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{
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if (SCM_CHARP(obj))
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return ((unsigned long) (scm_c_downcase (SCM_CHAR (obj)))) % n; /* downcase!?!! */
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if (SCM_NUMP(obj))
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return (unsigned long) scm_hasher(obj, n, 10);
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else
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return SCM_UNPACK (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 @var{key} that is suitable for\n"
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"lookups in a hashtable of size @var{size}, where @code{eqv?} is\n"
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"used as the equality predicate. The function returns an\n"
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"integer in the range 0 to @var{size} - 1. Note that\n"
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"@code{(hashv key)} may use internal addresses. Thus two calls\n"
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"to hashv where the keys are @code{eqv?} are not guaranteed to\n"
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"deliver the same value if the key object gets garbage collected\n"
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"in between. This can happen, for example with symbols:\n"
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"@code{(hashv 'foo n) (gc) (hashv 'foo n)} may produce two\n"
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"different values, since @code{foo} will be garbage collected.")
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#define FUNC_NAME s_scm_hashv
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{
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unsigned long sz = scm_to_unsigned_integer (size, 1, ULONG_MAX);
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return scm_from_ulong (scm_ihashv (key, sz));
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}
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#undef FUNC_NAME
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unsigned long
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scm_ihash (SCM obj, unsigned long n)
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{
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return (unsigned long) 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 @var{key} that is suitable for\n"
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"lookups in a hashtable of size @var{size}, where @code{equal?}\n"
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"is used as the equality predicate. The function returns an\n"
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"integer in the range 0 to @var{size} - 1.")
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#define FUNC_NAME s_scm_hash
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{
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unsigned long sz = scm_to_unsigned_integer (size, 1, ULONG_MAX);
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return scm_from_ulong (scm_ihash (key, sz));
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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 "libguile/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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