Repair logic error in LIKE: should not return LIKE_ABORT
when reach end of pattern before end of text. Improve code comments.
This commit is contained in:
Tom Lane
parent
ea582ad7e7
commit
bee7cd2a36
|
|
@ -3,17 +3,14 @@
|
|||
* like.c
|
||||
* like expression handling code.
|
||||
*
|
||||
* Copyright (c) 1994, Regents of the University of California
|
||||
*
|
||||
*
|
||||
* IDENTIFICATION
|
||||
* /usr/local/devel/pglite/cvs/src/backend/utils/adt/like.c,v 1.1 1995/07/30 23:55:36 emkxp01 Exp
|
||||
*
|
||||
*
|
||||
* NOTES
|
||||
* A big hack of the regexp.c code!! Contributed by
|
||||
* Keith Parks <emkxp01@mtcc.demon.co.uk> (7/95).
|
||||
*
|
||||
* Copyright (c) 1994, Regents of the University of California
|
||||
*
|
||||
* IDENTIFICATION
|
||||
* $Header: /cvsroot/pgsql/src/backend/utils/adt/like.c,v 1.31 1999/09/07 19:09:46 tgl Exp $
|
||||
*
|
||||
*-------------------------------------------------------------------------
|
||||
*/
|
||||
|
|
@ -109,9 +106,7 @@ textnlike(struct varlena * s, struct varlena * p)
|
|||
}
|
||||
|
||||
|
||||
/* $Revision: 1.30 $
|
||||
** "like.c" A first attempt at a LIKE operator for Postgres95.
|
||||
**
|
||||
/*
|
||||
** 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.
|
||||
|
|
@ -125,8 +120,7 @@ textnlike(struct varlena * s, struct varlena * p)
|
|||
** 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. (I suspect the standard
|
||||
** handles "%%" as a single literal percent)
|
||||
** to leave in the '\' escape character handling.
|
||||
**
|
||||
** Keith Parks. <keith@mtcc.demon.co.uk>
|
||||
**
|
||||
|
|
@ -140,15 +134,21 @@ textnlike(struct varlena * s, struct varlena * p)
|
|||
#define LIKE_FALSE 0
|
||||
#define LIKE_ABORT -1
|
||||
|
||||
/*
|
||||
** Match text and p, return LIKE_TRUE, LIKE_FALSE, or LIKE_ABORT.
|
||||
*/
|
||||
/*--------------------
|
||||
* 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)
|
||||
{
|
||||
int matched;
|
||||
|
||||
for (; *p && *text; text ++, p++)
|
||||
for (; *p && *text; text++, p++)
|
||||
{
|
||||
switch (*p)
|
||||
{
|
||||
|
|
@ -157,47 +157,55 @@ DoMatch(pg_wchar * text, pg_wchar * p)
|
|||
p++;
|
||||
/* FALLTHROUGH */
|
||||
default:
|
||||
if (*text !=*p)
|
||||
if (*text != *p)
|
||||
return LIKE_FALSE;
|
||||
break;
|
||||
case '_':
|
||||
/* Match anything. */
|
||||
/* 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')
|
||||
/* Trailing percent matches everything. */
|
||||
return LIKE_TRUE;
|
||||
while (*text)
|
||||
/* Otherwise, scan for a text position at which we
|
||||
* can match the rest of the pattern.
|
||||
*/
|
||||
for (; *text; text++)
|
||||
{
|
||||
/* Optimization to prevent most recursion */
|
||||
if ((*text == *p ||
|
||||
*p == '\\' || *p == '%' || *p == '_') &&
|
||||
(matched = DoMatch(text, p)) != LIKE_FALSE)
|
||||
return matched;
|
||||
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_ABORT;
|
||||
else
|
||||
{
|
||||
/* End of input string. Do we have matching string remaining? */
|
||||
while (*p == '%') /* allow multiple %'s at end of pattern */
|
||||
p++;
|
||||
if (*p == '\0')
|
||||
return LIKE_TRUE;
|
||||
else
|
||||
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.
|
||||
|
|
@ -205,6 +213,7 @@ DoMatch(pg_wchar * text, pg_wchar * p)
|
|||
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;
|
||||
|
|
|
|||
Loading…
Reference in New Issue