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/*----------------------------------------------------------------------------
*
* soundex.c
*
* Copyright (c) 2008-2018, Euler Taveira de Oliveira
*
*----------------------------------------------------------------------------
*/
#include "similarity.h"
static const char *stable =
/* ABCDEFGHIJKLMNOPQRSTUVWXYZ */
"01230120022455012623010202";
/*
* soundex code is only defined to ASCII characters
*/
static char convert_soundex(char a)
{
a = toupper((unsigned char) a);
/* soundex code is only defined to ASCII characters */
if (a >= 'A' && a <= 'Z')
return stable[a - 'A'];
else
return a;
}
static char *_soundex(char *a)
{
int alen;
int i;
int len;
char *scode;
int lastcode = PGS_SOUNDEX_INV_CODE;
alen = strlen(a);
elog(DEBUG2, "alen: %d", alen);
if (alen == 0)
return NULL;
#ifdef PGS_IGNORE_CASE
elog(DEBUG2, "case-sensitive turns off");
for (i = 0; i < alen; i++)
a[i] = toupper(a[i]);
#endif
scode = palloc(PGS_SOUNDEX_LEN + 1);
scode[PGS_SOUNDEX_LEN] = '\0';
/* ignoring non-alpha characters */
while (!isalpha(*a) && *a != '\0')
a++;
if (*a == '\0')
elog(ERROR, "string doesn't contain non-alpha character(s)");
/* get the first letter */
scode[0] = *a++;
len = 1;
elog(DEBUG2, "The first letter is: %c", scode[0]);
while (*a && len < PGS_SOUNDEX_LEN)
{
int curcode = convert_soundex(*a);
elog(DEBUG3, "The code for '%c' is: %d", *a, curcode);
if (isalpha(*a) && (curcode != lastcode) && curcode != '0')
{
scode[len] = curcode;
elog(DEBUG2, "scode[%d] = %d", len, curcode);
len++;
}
lastcode = curcode;
a++;
}
/* fill with zeros (if necessary) */
while (len < PGS_SOUNDEX_LEN)
{
scode[len] = '0';
elog(DEBUG2, "scode[%d] = %d", len, scode[len]);
len++;
}
return scode;
}
PG_FUNCTION_INFO_V1(soundex);
Datum
soundex(PG_FUNCTION_ARGS)
{
char *a, *b;
char *resa;
char *resb;
float8 res;
a = DatumGetPointer(DirectFunctionCall1(textout, PointerGetDatum(PG_GETARG_TEXT_P(0))));
b = DatumGetPointer(DirectFunctionCall1(textout, PointerGetDatum(PG_GETARG_TEXT_P(1))));
if (strlen(a) > PGS_MAX_STR_LEN || strlen(b) > PGS_MAX_STR_LEN)
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("argument exceeds the maximum length of %d bytes",
PGS_MAX_STR_LEN)));
resa = _soundex(a);
resb = _soundex(b);
elog(DEBUG1, "soundex(%s) = %s", a, resa);
elog(DEBUG1, "soundex(%s) = %s", b, resb);
/*
* we don't have threshold in soundex algorithm, instead same code means strings
* are similar (i.e. threshold is 1.0) or it is not (i.e. threshold is 0.0).
*/
if (strncmp(resa, resb, PGS_SOUNDEX_LEN) == 0)
res = 1.0;
else
res = 0.0;
PG_RETURN_FLOAT8(res);
}
PG_FUNCTION_INFO_V1(soundex_op);
Datum soundex_op(PG_FUNCTION_ARGS)
{
float8 res;
res = DatumGetFloat8(DirectFunctionCall2(
soundex,
PG_GETARG_DATUM(0),
PG_GETARG_DATUM(1)));
PG_RETURN_BOOL(res == 1.0);
}
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