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/*-------------------------------------------------------------------------
*
* like.c
* like expression handling code.
*
* NOTES
* A big hack of the regexp.c code!! Contributed by
* Keith Parks <emkxp01@mtcc.demon.co.uk> (7/95).
*
* Portions Copyright (c) 1996-2000, PostgreSQL, Inc
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/utils/adt/like.c,v 1.34 2000/04/12 17:15:50 momjian Exp $
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "mb/pg_wchar.h"
#include "utils/builtins.h"
static int like(pg_wchar * text, pg_wchar * p);
/*
* interface routines called by the function manager
*/
/*
fixedlen_like:
a generic fixed length like routine
s - the string to match against (not necessarily null-terminated)
p - the pattern
charlen - the length of the string
*/
static bool
fixedlen_like(char *s, struct varlena * p, int charlen)
{
pg_wchar *sterm,
*pterm;
int result;
int len;
if (!s || !p)
return FALSE;
/* be sure sterm is null-terminated */
#ifdef MULTIBYTE
sterm = (pg_wchar *) palloc((charlen + 1) * sizeof(pg_wchar));
(void) pg_mb2wchar_with_len((unsigned char *) s, sterm, charlen);
#else
sterm = (char *) palloc(charlen + 1);
StrNCpy(sterm, s, charlen + 1);
#endif
/*
* p is a text = varlena, not a string so we have to make a string
* from the vl_data field of the struct.
*/
/* palloc the length of the text + the null character */
len = VARSIZE(p) - VARHDRSZ;
#ifdef MULTIBYTE
pterm = (pg_wchar *) palloc((len + 1) * sizeof(pg_wchar));
(void) pg_mb2wchar_with_len((unsigned char *) VARDATA(p), pterm, len);
#else
pterm = (char *) palloc(len + 1);
memmove(pterm, VARDATA(p), len);
*(pterm + len) = (char) NULL;
#endif
/* do the regexp matching */
result = like(sterm, pterm);
pfree(sterm);
pfree(pterm);
return (bool) result;
}
bool
namelike(NameData *n, struct varlena * p)
{
if (!n)
return FALSE;
return fixedlen_like(NameStr(*n), p, NAMEDATALEN);
}
bool
namenlike(NameData *s, struct varlena * p)
{
return !namelike(s, p);
}
bool
textlike(struct varlena * s, struct varlena * p)
{
if (!s)
return FALSE;
return fixedlen_like(VARDATA(s), p, VARSIZE(s) - VARHDRSZ);
}
bool
textnlike(struct varlena * s, struct varlena * p)
{
return !textlike(s, p);
}
/*
** Originally written by Rich $alz, mirror!rs, Wed Nov 26 19:03:17 EST 1986.
** Rich $alz is now <rsalz@bbn.com>.
** Special thanks to Lars Mathiesen <thorinn@diku.dk> for the LABORT code.
**
** This code was shamelessly stolen from the "pql" code by myself and
** slightly modified :)
**
** All references to the word "star" were replaced by "percent"
** All references to the word "wild" were replaced by "like"
**
** All the nice shell RE matching stuff was replaced by just "_" and "%"
**
** As I don't have a copy of the SQL standard handy I wasn't sure whether
** to leave in the '\' escape character handling.
**
** Keith Parks. <keith@mtcc.demon.co.uk>
**
** [SQL92 lets you specify the escape character by saying
** LIKE <pattern> ESCAPE <escape character>. We are a small operation
** so we force you to use '\'. - ay 7/95]
**
*/
#define LIKE_TRUE 1
#define LIKE_FALSE 0
#define LIKE_ABORT -1
/*--------------------
* Match text and p, return LIKE_TRUE, LIKE_FALSE, or LIKE_ABORT.
*
* LIKE_TRUE: they match
* LIKE_FALSE: they don't match
* LIKE_ABORT: not only don't they match, but the text is too short.
*
* If LIKE_ABORT is returned, then no suffix of the text can match the
* pattern either, so an upper-level % scan can stop scanning now.
*--------------------
*/
static int
DoMatch(pg_wchar * text, pg_wchar * p)
{
for (; *p && *text; text ++, p++)
{
switch (*p)
{
case '\\':
/* Literal match with following character. */
p++;
/* FALLTHROUGH */
default:
if (*text !=*p)
return LIKE_FALSE;
break;
case '_':
/* Match any single character. */
break;
case '%':
/* %% is the same as % according to the SQL standard */
/* Advance past all %'s */
while (*p == '%')
p++;
/* Trailing percent matches everything. */
if (*p == '\0')
return LIKE_TRUE;
/*
* Otherwise, scan for a text position at which we can
* match the rest of the pattern.
*/
for (; *text; text ++)
{
/*
* Optimization to prevent most recursion: don't
* recurse unless first pattern char might match this
* text char.
*/
if (*text == *p || *p == '\\' || *p == '_')
{
int matched = DoMatch(text, p);
if (matched != LIKE_FALSE)
return matched; /* TRUE or ABORT */
}
}
/*
* End of text with no match, so no point in trying later
* places to start matching this pattern.
*/
return LIKE_ABORT;
}
}
if (*text !='\0')
return LIKE_FALSE; /* end of pattern, but not of text */
/* End of input string. Do we have matching pattern remaining? */
while (*p == '%') /* allow multiple %'s at end of pattern */
p++;
if (*p == '\0')
return LIKE_TRUE;
/*
* End of text with no match, so no point in trying later places to
* start matching this pattern.
*/
return LIKE_ABORT;
}
/*
** User-level routine. Returns TRUE or FALSE.
*/
static int
like(pg_wchar * text, pg_wchar * p)
{
/* Fast path for match-everything pattern */
if (p[0] == '%' && p[1] == '\0')
return TRUE;
return DoMatch(text, p) == LIKE_TRUE;
}
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