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/* Copyright (C) 1995,1996,1997, 2000, 2001 Free Software Foundation, Inc.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2, or (at your option)
* any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this software; see the file COPYING. If not, write to
* the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
* Boston, MA 02111-1307 USA
*
* As a special exception, the Free Software Foundation gives permission
* for additional uses of the text contained in its release of GUILE.
*
* The exception is that, if you link the GUILE library with other files
* to produce an executable, this does not by itself cause the
* resulting executable to be covered by the GNU General Public License.
* Your use of that executable is in no way restricted on account of
* linking the GUILE library code into it.
*
* This exception does not however invalidate any other reasons why
* the executable file might be covered by the GNU General Public License.
*
* This exception applies only to the code released by the
* Free Software Foundation under the name GUILE. If you copy
* code from other Free Software Foundation releases into a copy of
* GUILE, as the General Public License permits, the exception does
* not apply to the code that you add in this way. To avoid misleading
* anyone as to the status of such modified files, you must delete
* this exception notice from them.
*
* If you write modifications of your own for GUILE, it is your choice
* whether to permit this exception to apply to your modifications.
* If you do not wish that, delete this exception notice. */
/* Software engineering face-lift by Greg J. Badros, 11-Dec-1999,
gjb@cs.washington.edu, http://www.cs.washington.edu/homes/gjb */
#include "libguile/_scm.h"
#include "libguile/chars.h"
#include "libguile/ports.h"
#include "libguile/strings.h"
#include "libguile/symbols.h"
#include "libguile/vectors.h"
#include "libguile/validate.h"
#include "libguile/hash.h"
#ifndef floor
extern double floor();
#endif
unsigned long
scm_string_hash (const unsigned char *str, size_t len)
{
if (len > 5)
{
size_t i = 5;
unsigned long h = 264;
while (i--)
h = (h << 8) + (unsigned) str[h % len];
return h;
}
else
{
size_t i = len;
unsigned long h = 0;
while (i)
h = (h << 8) + (unsigned) str[--i];
return h;
}
}
/* Dirk:FIXME:: why downcase for characters? (2x: scm_hasher, scm_ihashv) */
/* Dirk:FIXME:: scm_hasher could be made static. */
unsigned long
scm_hasher(SCM obj, unsigned long n, size_t d)
{
switch (SCM_ITAG3 (obj)) {
case scm_tc3_int_1:
case scm_tc3_int_2:
return SCM_INUM(obj) % n; /* SCM_INUMP(obj) */
case scm_tc3_imm24:
if (SCM_CHARP(obj))
return (unsigned)(scm_downcase(SCM_CHAR(obj))) % n;
switch (SCM_UNPACK (obj)) {
#ifndef SICP
case SCM_UNPACK(SCM_EOL):
d = 256;
break;
#endif
case SCM_UNPACK(SCM_BOOL_T):
d = 257;
break;
case SCM_UNPACK(SCM_BOOL_F):
d = 258;
break;
case SCM_UNPACK(SCM_EOF_VAL):
d = 259;
break;
default:
d = 263; /* perhaps should be error */
}
return d % n;
default:
return 263 % n; /* perhaps should be error */
case scm_tc3_cons:
switch SCM_TYP7(obj) {
default:
return 263 % n;
case scm_tc7_smob:
switch SCM_TYP16 (obj) {
case scm_tc16_big:
return SCM_INUM (scm_modulo (obj, SCM_MAKINUM (n)));
default:
return 263 % n;
case scm_tc16_real:
{
double r = SCM_REAL_VALUE (obj);
if (floor (r) == r) {
obj = scm_inexact_to_exact (obj);
if SCM_IMP (obj) return SCM_INUM (obj) % n;
return SCM_INUM (scm_modulo (obj, SCM_MAKINUM (n)));
}
}
case scm_tc16_complex:
obj = scm_number_to_string (obj, SCM_MAKINUM (10));
}
case scm_tc7_string:
case scm_tc7_substring:
return scm_string_hash (SCM_STRING_UCHARS (obj), SCM_STRING_LENGTH (obj)) % n;
case scm_tc7_symbol:
return SCM_SYMBOL_HASH (obj) % n;
case scm_tc7_wvect:
case scm_tc7_vector:
{
size_t len = SCM_VECTOR_LENGTH(obj);
SCM *data = SCM_VELTS(obj);
if (len > 5)
{
size_t i = d/2;
unsigned long h = 1;
while (i--) h = ((h << 8) + (scm_hasher (data[h % len], n, 2))) % n;
return h;
}
else
{
size_t i = len;
unsigned long h = (n)-1;
while (i--) h = ((h << 8) + (scm_hasher (data[i], n, d/len))) % n;
return h;
}
}
case scm_tcs_cons_imcar:
case scm_tcs_cons_nimcar:
if (d) return (scm_hasher (SCM_CAR (obj), n, d/2)
+ scm_hasher (SCM_CDR (obj), n, d/2)) % n;
else return 1;
case scm_tc7_port:
return ((SCM_RDNG & SCM_CELL_WORD_0 (obj)) ? 260 : 261) % n;
case scm_tcs_closures:
case scm_tcs_subrs:
return 262 % n;
}
}
}
unsigned long
scm_ihashq (SCM obj, unsigned long n)
{
return (SCM_UNPACK (obj) >> 1) % n;
}
SCM_DEFINE (scm_hashq, "hashq", 2, 0, 0,
(SCM key, SCM size),
"Determine a hash value for @var{key} that is suitable for\n"
"lookups in a hashtable of size @var{size}, where @code{eq?} is\n"
"used as the equality predicate. The function returns an\n"
"integer in the range 0 to @var{size} - 1. Note that\n"
"@code{hashq} may use internal addresses. Thus two calls to\n"
"hashq where the keys are @code{eq?} are not guaranteed to\n"
"deliver the same value if the key object gets garbage collected\n"
"in between. This can happen, for example with symbols:\n"
"@code{(hashq 'foo n) (gc) (hashq 'foo n)} may produce two\n"
"different values, since @code{foo} will be garbage collected.")
#define FUNC_NAME s_scm_hashq
{
SCM_VALIDATE_INUM_MIN (2, size, 0);
return SCM_MAKINUM (scm_ihashq (key, SCM_INUM (size)));
}
#undef FUNC_NAME
unsigned long
scm_ihashv (SCM obj, unsigned long n)
{
if (SCM_CHARP(obj))
return ((unsigned long) (scm_downcase (SCM_CHAR (obj)))) % n; /* downcase!?!! */
if (SCM_NUMP(obj))
return (unsigned long) scm_hasher(obj, n, 10);
else
return SCM_UNPACK (obj) % n;
}
SCM_DEFINE (scm_hashv, "hashv", 2, 0, 0,
(SCM key, SCM size),
"Determine a hash value for @var{key} that is suitable for\n"
"lookups in a hashtable of size @var{size}, where @code{eqv?} is\n"
"used as the equality predicate. The function returns an\n"
"integer in the range 0 to @var{size} - 1. Note that\n"
"@code{(hashv key)} may use internal addresses. Thus two calls\n"
"to hashv where the keys are @code{eqv?} are not guaranteed to\n"
"deliver the same value if the key object gets garbage collected\n"
"in between. This can happen, for example with symbols:\n"
"@code{(hashv 'foo n) (gc) (hashv 'foo n)} may produce two\n"
"different values, since @code{foo} will be garbage collected.")
#define FUNC_NAME s_scm_hashv
{
SCM_VALIDATE_INUM_MIN (2, size, 0);
return SCM_MAKINUM (scm_ihashv (key, SCM_INUM (size)));
}
#undef FUNC_NAME
unsigned long
scm_ihash (SCM obj, unsigned long n)
{
return (unsigned long) scm_hasher (obj, n, 10);
}
SCM_DEFINE (scm_hash, "hash", 2, 0, 0,
(SCM key, SCM size),
"Determine a hash value for @var{key} that is suitable for\n"
"lookups in a hashtable of size @var{size}, where @code{equal?}\n"
"is used as the equality predicate. The function returns an\n"
"integer in the range 0 to @var{size} - 1.")
#define FUNC_NAME s_scm_hash
{
SCM_VALIDATE_INUM_MIN (2, size, 0);
return SCM_MAKINUM (scm_ihash (key, SCM_INUM (size)));
}
#undef FUNC_NAME
void
scm_init_hash ()
{
#ifndef SCM_MAGIC_SNARFER
#include "libguile/hash.x"
#endif
}
/*
Local Variables:
c-file-style: "gnu"
End:
*/
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