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Improve efficiency of LIKE/ILIKE code, especially for multi-byte charsets,

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and most especially for UTF8. Remove unnecessary special cases for bytea
processing and single-byte charset ILIKE.  a ILIKE b is now processed as
lower(a) LIKE lower(b) in all cases. The code is now considerably simpler. All
comparisons are now performed byte-wise, and the text and pattern are also
advanced byte-wise where it is safe to do so - essentially where a wildcard is
not being matched.
Andrew Dunstan, from an original patch by ITAGAKI Takahiro, with ideas from
Tom Lane and Mark Mielke.
This commit is contained in:
Andrew Dunstan
2007-06-02 02:03:42 +00:00
parent 964ec46cfe
commit 15f8202c20
2 changed files with 191 additions and 447 deletions
Download Patch File Download Diff File Expand all files Collapse all files

402
src/backend/utils/adt/like.c
View File

@ -11,7 +11,7 @@
* Portions Copyright (c) 1994, Regents of the University of California * Portions Copyright (c) 1994, Regents of the University of California
* *
* IDENTIFICATION * IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/utils/adt/like.c,v 1.68 2007/02/27 23:48:08 tgl Exp $ * $PostgreSQL: pgsql/src/backend/utils/adt/like.c,v 1.69 2007/06/02 02:03:42 adunstan Exp $
* *
*------------------------------------------------------------------------- *-------------------------------------------------------------------------
*/ */
@ -28,21 +28,23 @@
#define LIKE_ABORT (-1) #define LIKE_ABORT (-1)
static int MatchText(char *t, int tlen, char *p, int plen); static int SB_MatchText(char *t, int tlen, char *p, int plen);
static int MatchTextIC(char *t, int tlen, char *p, int plen); static text *SB_do_like_escape(text *, text *);
static int MatchBytea(char *t, int tlen, char *p, int plen);
static text *do_like_escape(text *, text *);
static int MBMatchText(char *t, int tlen, char *p, int plen); static int MB_MatchText(char *t, int tlen, char *p, int plen);
static int MBMatchTextIC(char *t, int tlen, char *p, int plen);
static text *MB_do_like_escape(text *, text *); static text *MB_do_like_escape(text *, text *);
static int UTF8_MatchText(char *t, int tlen, char *p, int plen);
static int GenericMatchText(char *s, int slen, char* p, int plen);
static int Generic_Text_IC_like(text *str, text *pat);
/*-------------------- /*--------------------
* Support routine for MatchText. Compares given multibyte streams * Support routine for MatchText. Compares given multibyte streams
* as wide characters. If they match, returns 1 otherwise returns 0. * as wide characters. If they match, returns 1 otherwise returns 0.
*-------------------- *--------------------
*/ */
static int static inline int
wchareq(char *p1, char *p2) wchareq(char *p1, char *p2)
{ {
int p1_len; int p1_len;
@ -72,15 +74,12 @@ wchareq(char *p1, char *p2)
* of getting a single character transformed to the system's wchar_t format. * of getting a single character transformed to the system's wchar_t format.
* So now, we just downcase the strings using lower() and apply regular LIKE * So now, we just downcase the strings using lower() and apply regular LIKE
* comparison. This should be revisited when we install better locale support. * comparison. This should be revisited when we install better locale support.
*
* Note that MBMatchText and MBMatchTextIC do exactly the same thing now.
* Is it worth refactoring to avoid duplicated code? They might become
* different again in the future.
*/ */
#define NextByte(p, plen) ((p)++, (plen)--)
/* Set up to compile like_match.c for multibyte characters */ /* Set up to compile like_match.c for multibyte characters */
#define CHAREQ(p1, p2) wchareq(p1, p2) #define CHAREQ(p1, p2) wchareq((p1), (p2))
#define ICHAREQ(p1, p2) wchareq(p1, p2)
#define NextChar(p, plen) \ #define NextChar(p, plen) \
do { int __l = pg_mblen(p); (p) +=__l; (plen) -=__l; } while (0) do { int __l = pg_mblen(p); (p) +=__l; (plen) -=__l; } while (0)
#define CopyAdvChar(dst, src, srclen) \ #define CopyAdvChar(dst, src, srclen) \
@ -90,33 +89,59 @@ wchareq(char *p1, char *p2)
*(dst)++ = *(src)++; \ *(dst)++ = *(src)++; \
} while (0) } while (0)
#define MatchText MBMatchText #define MatchText MB_MatchText
#define MatchTextIC MBMatchTextIC
#define do_like_escape MB_do_like_escape #define do_like_escape MB_do_like_escape
#include "like_match.c" #include "like_match.c"
#undef CHAREQ
#undef ICHAREQ
#undef NextChar
#undef CopyAdvChar
#undef MatchText
#undef MatchTextIC
#undef do_like_escape
/* Set up to compile like_match.c for single-byte characters */ /* Set up to compile like_match.c for single-byte characters */
#define CHAREQ(p1, p2) (*(p1) == *(p2)) #define CHAREQ(p1, p2) (*(p1) == *(p2))
#define ICHAREQ(p1, p2) (tolower((unsigned char) *(p1)) == tolower((unsigned char) *(p2))) #define NextChar(p, plen) NextByte((p), (plen))
#define NextChar(p, plen) ((p)++, (plen)--)
#define CopyAdvChar(dst, src, srclen) (*(dst)++ = *(src)++, (srclen)--) #define CopyAdvChar(dst, src, srclen) (*(dst)++ = *(src)++, (srclen)--)
#define MatchText SB_MatchText
#define do_like_escape SB_do_like_escape
#include "like_match.c" #include "like_match.c"
/* And some support for BYTEA */
#define BYTEA_CHAREQ(p1, p2) (*(p1) == *(p2))
#define BYTEA_NextChar(p, plen) ((p)++, (plen)--)
#define BYTEA_CopyAdvChar(dst, src, srclen) (*(dst)++ = *(src)++, (srclen)--)
/* setup to compile like_match.c for UTF8 encoding, using fast NextChar */
#define NextChar(p, plen) \
do { (p)++; (plen)--; } while ((plen) > 0 && (*(p) & 0xC0) == 0x80 )
#define MatchText UTF8_MatchText
#include "like_match.c"
static inline int
GenericMatchText(char *s, int slen, char* p, int plen)
{
if (pg_database_encoding_max_length() == 1)
return SB_MatchText(s, slen, p, plen);
else if (GetDatabaseEncoding() == PG_UTF8)
return UTF8_MatchText(s, slen, p, plen);
else
return MB_MatchText(s, slen, p, plen);
}
static inline int
Generic_Text_IC_like(text *str, text *pat)
{
char *s,
*p;
int slen,
plen;
/* Force inputs to lower case to achieve case insensitivity */
str = DatumGetTextP(DirectFunctionCall1(lower, PointerGetDatum(str)));
pat = DatumGetTextP(DirectFunctionCall1(lower, PointerGetDatum(pat)));
s = VARDATA(str);
slen = (VARSIZE(str) - VARHDRSZ);
p = VARDATA(pat);
plen = (VARSIZE(pat) - VARHDRSZ);
return GenericMatchText(s, slen, p, plen);
}
/* /*
* interface routines called by the function manager * interface routines called by the function manager
@ -138,10 +163,7 @@ namelike(PG_FUNCTION_ARGS)
p = VARDATA(pat); p = VARDATA(pat);
plen = (VARSIZE(pat) - VARHDRSZ); plen = (VARSIZE(pat) - VARHDRSZ);
if (pg_database_encoding_max_length() == 1) result = (GenericMatchText(s, slen, p, plen) == LIKE_TRUE);
result = (MatchText(s, slen, p, plen) == LIKE_TRUE);
else
result = (MBMatchText(s, slen, p, plen) == LIKE_TRUE);
PG_RETURN_BOOL(result); PG_RETURN_BOOL(result);
} }
@ -162,10 +184,7 @@ namenlike(PG_FUNCTION_ARGS)
p = VARDATA(pat); p = VARDATA(pat);
plen = (VARSIZE(pat) - VARHDRSZ); plen = (VARSIZE(pat) - VARHDRSZ);
if (pg_database_encoding_max_length() == 1) result = (GenericMatchText(s, slen, p, plen) != LIKE_TRUE);
result = (MatchText(s, slen, p, plen) != LIKE_TRUE);
else
result = (MBMatchText(s, slen, p, plen) != LIKE_TRUE);
PG_RETURN_BOOL(result); PG_RETURN_BOOL(result);
} }
@ -186,10 +205,7 @@ textlike(PG_FUNCTION_ARGS)
p = VARDATA(pat); p = VARDATA(pat);
plen = (VARSIZE(pat) - VARHDRSZ); plen = (VARSIZE(pat) - VARHDRSZ);
if (pg_database_encoding_max_length() == 1) result = (GenericMatchText(s, slen, p, plen) == LIKE_TRUE);
result = (MatchText(s, slen, p, plen) == LIKE_TRUE);
else
result = (MBMatchText(s, slen, p, plen) == LIKE_TRUE);
PG_RETURN_BOOL(result); PG_RETURN_BOOL(result);
} }
@ -210,10 +226,7 @@ textnlike(PG_FUNCTION_ARGS)
p = VARDATA(pat); p = VARDATA(pat);
plen = (VARSIZE(pat) - VARHDRSZ); plen = (VARSIZE(pat) - VARHDRSZ);
if (pg_database_encoding_max_length() == 1) result = (GenericMatchText(s, slen, p, plen) != LIKE_TRUE);
result = (MatchText(s, slen, p, plen) != LIKE_TRUE);
else
result = (MBMatchText(s, slen, p, plen) != LIKE_TRUE);
PG_RETURN_BOOL(result); PG_RETURN_BOOL(result);
} }
@ -234,7 +247,7 @@ bytealike(PG_FUNCTION_ARGS)
p = VARDATA(pat); p = VARDATA(pat);
plen = (VARSIZE(pat) - VARHDRSZ); plen = (VARSIZE(pat) - VARHDRSZ);
result = (MatchBytea(s, slen, p, plen) == LIKE_TRUE); result = (SB_MatchText(s, slen, p, plen) == LIKE_TRUE);
PG_RETURN_BOOL(result); PG_RETURN_BOOL(result);
} }
@ -255,7 +268,7 @@ byteanlike(PG_FUNCTION_ARGS)
p = VARDATA(pat); p = VARDATA(pat);
plen = (VARSIZE(pat) - VARHDRSZ); plen = (VARSIZE(pat) - VARHDRSZ);
result = (MatchBytea(s, slen, p, plen) != LIKE_TRUE); result = (SB_MatchText(s, slen, p, plen) != LIKE_TRUE);
PG_RETURN_BOOL(result); PG_RETURN_BOOL(result);
} }
@ -270,37 +283,11 @@ nameiclike(PG_FUNCTION_ARGS)
Name str = PG_GETARG_NAME(0); Name str = PG_GETARG_NAME(0);
text *pat = PG_GETARG_TEXT_P(1); text *pat = PG_GETARG_TEXT_P(1);
bool result; bool result;
char *s, text *strtext;
*p;
int slen,
plen;
if (pg_database_encoding_max_length() == 1) strtext = DatumGetTextP(DirectFunctionCall1(name_text,
{
s = NameStr(*str);
slen = strlen(s);
p = VARDATA(pat);
plen = (VARSIZE(pat) - VARHDRSZ);
result = (MatchTextIC(s, slen, p, plen) == LIKE_TRUE);
}
else
{
/* Force inputs to lower case to achieve case insensitivity */
text *strtext;
strtext = DatumGetTextP(DirectFunctionCall1(name_text,
NameGetDatum(str))); NameGetDatum(str)));
strtext = DatumGetTextP(DirectFunctionCall1(lower, result = (Generic_Text_IC_like(strtext, pat) == LIKE_TRUE);
PointerGetDatum(strtext)));
pat = DatumGetTextP(DirectFunctionCall1(lower,
PointerGetDatum(pat)));
s = VARDATA(strtext);
slen = (VARSIZE(strtext) - VARHDRSZ);
p = VARDATA(pat);
plen = (VARSIZE(pat) - VARHDRSZ);
result = (MBMatchTextIC(s, slen, p, plen) == LIKE_TRUE);
}
PG_RETURN_BOOL(result); PG_RETURN_BOOL(result);
} }
@ -311,37 +298,11 @@ nameicnlike(PG_FUNCTION_ARGS)
Name str = PG_GETARG_NAME(0); Name str = PG_GETARG_NAME(0);
text *pat = PG_GETARG_TEXT_P(1); text *pat = PG_GETARG_TEXT_P(1);
bool result; bool result;
char *s, text *strtext;
*p;
int slen,
plen;
if (pg_database_encoding_max_length() == 1) strtext = DatumGetTextP(DirectFunctionCall1(name_text,
{
s = NameStr(*str);
slen = strlen(s);
p = VARDATA(pat);
plen = (VARSIZE(pat) - VARHDRSZ);
result = (MatchTextIC(s, slen, p, plen) != LIKE_TRUE);
}
else
{
/* Force inputs to lower case to achieve case insensitivity */
text *strtext;
strtext = DatumGetTextP(DirectFunctionCall1(name_text,
NameGetDatum(str))); NameGetDatum(str)));
strtext = DatumGetTextP(DirectFunctionCall1(lower, result = (Generic_Text_IC_like(strtext, pat) != LIKE_TRUE);
PointerGetDatum(strtext)));
pat = DatumGetTextP(DirectFunctionCall1(lower,
PointerGetDatum(pat)));
s = VARDATA(strtext);
slen = (VARSIZE(strtext) - VARHDRSZ);
p = VARDATA(pat);
plen = (VARSIZE(pat) - VARHDRSZ);
result = (MBMatchTextIC(s, slen, p, plen) != LIKE_TRUE);
}
PG_RETURN_BOOL(result); PG_RETURN_BOOL(result);
} }
@ -352,32 +313,8 @@ texticlike(PG_FUNCTION_ARGS)
text *str = PG_GETARG_TEXT_P(0); text *str = PG_GETARG_TEXT_P(0);
text *pat = PG_GETARG_TEXT_P(1); text *pat = PG_GETARG_TEXT_P(1);
bool result; bool result;
char *s,
*p;
int slen,
plen;
if (pg_database_encoding_max_length() == 1) result = (Generic_Text_IC_like(str, pat) == LIKE_TRUE);
{
s = VARDATA(str);
slen = (VARSIZE(str) - VARHDRSZ);
p = VARDATA(pat);
plen = (VARSIZE(pat) - VARHDRSZ);
result = (MatchTextIC(s, slen, p, plen) == LIKE_TRUE);
}
else
{
/* Force inputs to lower case to achieve case insensitivity */
str = DatumGetTextP(DirectFunctionCall1(lower,
PointerGetDatum(str)));
pat = DatumGetTextP(DirectFunctionCall1(lower,
PointerGetDatum(pat)));
s = VARDATA(str);
slen = (VARSIZE(str) - VARHDRSZ);
p = VARDATA(pat);
plen = (VARSIZE(pat) - VARHDRSZ);
result = (MBMatchTextIC(s, slen, p, plen) == LIKE_TRUE);
}
PG_RETURN_BOOL(result); PG_RETURN_BOOL(result);
} }
@ -388,32 +325,8 @@ texticnlike(PG_FUNCTION_ARGS)
text *str = PG_GETARG_TEXT_P(0); text *str = PG_GETARG_TEXT_P(0);
text *pat = PG_GETARG_TEXT_P(1); text *pat = PG_GETARG_TEXT_P(1);
bool result; bool result;
char *s,
*p;
int slen,
plen;
if (pg_database_encoding_max_length() == 1) result = (Generic_Text_IC_like(str, pat) != LIKE_TRUE);
{
s = VARDATA(str);
slen = (VARSIZE(str) - VARHDRSZ);
p = VARDATA(pat);
plen = (VARSIZE(pat) - VARHDRSZ);
result = (MatchTextIC(s, slen, p, plen) != LIKE_TRUE);
}
else
{
/* Force inputs to lower case to achieve case insensitivity */
str = DatumGetTextP(DirectFunctionCall1(lower,
PointerGetDatum(str)));
pat = DatumGetTextP(DirectFunctionCall1(lower,
PointerGetDatum(pat)));
s = VARDATA(str);
slen = (VARSIZE(str) - VARHDRSZ);
p = VARDATA(pat);
plen = (VARSIZE(pat) - VARHDRSZ);
result = (MBMatchTextIC(s, slen, p, plen) != LIKE_TRUE);
}
PG_RETURN_BOOL(result); PG_RETURN_BOOL(result);
} }
@ -430,7 +343,7 @@ like_escape(PG_FUNCTION_ARGS)
text *result; text *result;
if (pg_database_encoding_max_length() == 1) if (pg_database_encoding_max_length() == 1)
result = do_like_escape(pat, esc); result = SB_do_like_escape(pat, esc);
else else
result = MB_do_like_escape(pat, esc); result = MB_do_like_escape(pat, esc);
@ -446,179 +359,8 @@ like_escape_bytea(PG_FUNCTION_ARGS)
{ {
bytea *pat = PG_GETARG_BYTEA_P(0); bytea *pat = PG_GETARG_BYTEA_P(0);
bytea *esc = PG_GETARG_BYTEA_P(1); bytea *esc = PG_GETARG_BYTEA_P(1);
bytea *result; bytea *result = SB_do_like_escape((text *)pat, (text *)esc);
char *p,
*e,
*r;
int plen,
elen;
bool afterescape;
p = VARDATA(pat); PG_RETURN_BYTEA_P((bytea *)result);
plen = (VARSIZE(pat) - VARHDRSZ);
e = VARDATA(esc);
elen = (VARSIZE(esc) - VARHDRSZ);
/*
* Worst-case pattern growth is 2x --- unlikely, but it's hardly worth
* trying to calculate the size more accurately than that.
*/
result = (text *) palloc(plen * 2 + VARHDRSZ);
r = VARDATA(result);
if (elen == 0)
{
/*
* No escape character is wanted. Double any backslashes in the
* pattern to make them act like ordinary characters.
*/
while (plen > 0)
{
if (*p == '\\')
*r++ = '\\';
BYTEA_CopyAdvChar(r, p, plen);
}
}
else
{
/*
* The specified escape must be only a single character.
*/
BYTEA_NextChar(e, elen);
if (elen != 0)
ereport(ERROR,
(errcode(ERRCODE_INVALID_ESCAPE_SEQUENCE),
errmsg("invalid escape string"),
errhint("Escape string must be empty or one character.")));
e = VARDATA(esc);
/*
* If specified escape is '\', just copy the pattern as-is.
*/
if (*e == '\\')
{
memcpy(result, pat, VARSIZE(pat));
PG_RETURN_BYTEA_P(result);
}
/*
* Otherwise, convert occurrences of the specified escape character to
* '\', and double occurrences of '\' --- unless they immediately
* follow an escape character!
*/
afterescape = false;
while (plen > 0)
{
if (BYTEA_CHAREQ(p, e) && !afterescape)
{
*r++ = '\\';
BYTEA_NextChar(p, plen);
afterescape = true;
}
else if (*p == '\\')
{
*r++ = '\\';
if (!afterescape)
*r++ = '\\';
BYTEA_NextChar(p, plen);
afterescape = false;
}
else
{
BYTEA_CopyAdvChar(r, p, plen);
afterescape = false;
}
}
}
SET_VARSIZE(result, r - ((char *) result));
PG_RETURN_BYTEA_P(result);
} }
/*
* Same as above, but specifically for bytea (binary) datatype
*/
static int
MatchBytea(char *t, int tlen, char *p, int plen)
{
/* Fast path for match-everything pattern */
if ((plen == 1) && (*p == '%'))
return LIKE_TRUE;
while ((tlen > 0) && (plen > 0))
{
if (*p == '\\')
{
/* Next pattern char must match literally, whatever it is */
BYTEA_NextChar(p, plen);
if ((plen <= 0) || !BYTEA_CHAREQ(t, p))
return LIKE_FALSE;
}
else if (*p == '%')
{
/* %% is the same as % according to the SQL standard */
/* Advance past all %'s */
while ((plen > 0) && (*p == '%'))
BYTEA_NextChar(p, plen);
/* Trailing percent matches everything. */
if (plen <= 0)
return LIKE_TRUE;
/*
* Otherwise, scan for a text position at which we can match the
* rest of the pattern.
*/
while (tlen > 0)
{
/*
* Optimization to prevent most recursion: don't recurse
* unless first pattern char might match this text char.
*/
if (BYTEA_CHAREQ(t, p) || (*p == '\\') || (*p == '_'))
{
int matched = MatchBytea(t, tlen, p, plen);
if (matched != LIKE_FALSE)
return matched; /* TRUE or ABORT */
}
BYTEA_NextChar(t, tlen);
}
/*
* End of text with no match, so no point in trying later places
* to start matching this pattern.
*/
return LIKE_ABORT;
}
else if ((*p != '_') && !BYTEA_CHAREQ(t, p))
{
/*
* Not the single-character wildcard and no explicit match? Then
* time to quit...
*/
return LIKE_FALSE;
}
BYTEA_NextChar(t, tlen);
BYTEA_NextChar(p, plen);
}
if (tlen > 0)
return LIKE_FALSE; /* end of pattern, but not of text */
/* End of input string. Do we have matching pattern remaining? */
while ((plen > 0) && (*p == '%')) /* allow multiple %'s at end of
* pattern */
BYTEA_NextChar(p, plen);
if (plen <= 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;
} /* MatchBytea() */

236
src/backend/utils/adt/like_match.c
View File

@ -3,23 +3,21 @@
* like_match.c * like_match.c
* like expression handling internal code. * like expression handling internal code.
* *
* This file is included by like.c *twice*, to provide an optimization * This file is included by like.c three times, to provide natching code for
* for single-byte encodings. * single-byte encodings, UTF8, and for other multi-byte encodings.
* UTF8 is a special case because we can use a much more efficient version
* of NextChar than can be used for other multi-byte encodings.
* *
* Before the inclusion, we need to define following macros: * Before the inclusion, we need to define following macros:
* *
* CHAREQ * NextChar
* ICHAREQ * MatchText - to name of function wanted
* NextChar * do_like_escape - name of function if wanted - needs CHAREQ and CopyAdvChar
* CopyAdvChar
* MatchText (MBMatchText)
* MatchTextIC (MBMatchTextIC)
* do_like_escape (MB_do_like_escape)
* *
* Copyright (c) 1996-2007, PostgreSQL Global Development Group * Copyright (c) 1996-2007, PostgreSQL Global Development Group
* *
* IDENTIFICATION * IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/utils/adt/like_match.c,v 1.15 2007/02/27 23:48:08 tgl Exp $ * $PostgreSQL: pgsql/src/backend/utils/adt/like_match.c,v 1.16 2007/06/02 02:03:42 adunstan Exp $
* *
*------------------------------------------------------------------------- *-------------------------------------------------------------------------
*/ */
@ -77,21 +75,36 @@ MatchText(char *t, int tlen, char *p, int plen)
if ((plen == 1) && (*p == '%')) if ((plen == 1) && (*p == '%'))
return LIKE_TRUE; return LIKE_TRUE;
/*
* In this loop, we advance by char when matching wildcards (and thus
* on recursive entry to this function we are properly char-synced). On
* other occasions it is safe to advance by byte, as the text and pattern
* will be in lockstep. This allows us to perform all comparisons between
* the text and pattern on a byte by byte basis, even for multi-byte
* encodings.
*/
while ((tlen > 0) && (plen > 0)) while ((tlen > 0) && (plen > 0))
{ {
if (*p == '\\') if (*p == '\\')
{ {
/* Next pattern char must match literally, whatever it is */ /* Next byte must match literally, whatever it is */
NextChar(p, plen); NextByte(p, plen);
if ((plen <= 0) || !CHAREQ(t, p)) if ((plen <= 0) || *p != *t )
return LIKE_FALSE; return LIKE_FALSE;
} }
else if (*p == '%') else if (*p == '%')
{ {
/*
* % processing is essentially a search for a match for what
* follows the %, plus a recursive match of the remainder.
* We succeed if and only if both conditions are met.
*/
/* %% is the same as % according to the SQL standard */ /* %% is the same as % according to the SQL standard */
/* Advance past all %'s */ /* Advance past all %'s */
while ((plen > 0) && (*p == '%')) while ((plen > 0) && (*p == '%'))
NextChar(p, plen); NextByte(p, plen);
/* Trailing percent matches everything. */ /* Trailing percent matches everything. */
if (plen <= 0) if (plen <= 0)
return LIKE_TRUE; return LIKE_TRUE;
@ -100,21 +113,62 @@ MatchText(char *t, int tlen, char *p, int plen)
* Otherwise, scan for a text position at which we can match the * Otherwise, scan for a text position at which we can match the
* rest of the pattern. * rest of the pattern.
*/ */
while (tlen > 0) if (*p == '_')
{
/*
* Optimization to prevent most recursion: don't recurse
* unless first pattern char might match this text char.
*/
if (CHAREQ(t, p) || (*p == '\\') || (*p == '_'))
{
int matched = MatchText(t, tlen, p, plen);
if (matched != LIKE_FALSE) {
return matched; /* TRUE or ABORT */ /* %_ is the same as _% - avoid matching _ repeatedly */
}
NextChar(t, tlen); NextChar(t, tlen);
NextByte(p, plen);
if (tlen <= 0)
{
return (plen <= 0) ? LIKE_TRUE : LIKE_ABORT;
}
else if (plen <= 0)
{
return LIKE_FALSE;
}
while (tlen > 0)
{
int matched = MatchText(t, tlen, p, plen);
if (matched != LIKE_FALSE)
return matched; /* TRUE or ABORT */
NextChar(t, tlen);
}
}
else
{
char firstpat = *p ;
if (*p == '\\')
{
if (plen < 2)
return LIKE_FALSE;
firstpat = p[1];
}
while (tlen > 0)
{
/*
* Optimization to prevent most recursion: don't recurse
* unless first pattern byte matches first text byte.
*/
if (*t == firstpat)
{
int matched = MatchText(t, tlen, p, plen);
if (matched != LIKE_FALSE)
return matched; /* TRUE or ABORT */
}
NextChar(t, tlen);
}
} }
/* /*
@ -123,7 +177,13 @@ MatchText(char *t, int tlen, char *p, int plen)
*/ */
return LIKE_ABORT; return LIKE_ABORT;
} }
else if ((*p != '_') && !CHAREQ(t, p)) else if (*p == '_')
{
NextChar(t, tlen);
NextByte(p, plen);
continue;
}
else if (*t != *p)
{ {
/* /*
* Not the single-character wildcard and no explicit match? Then * Not the single-character wildcard and no explicit match? Then
@ -131,9 +191,20 @@ MatchText(char *t, int tlen, char *p, int plen)
*/ */
return LIKE_FALSE; return LIKE_FALSE;
} }
/*
NextChar(t, tlen); * It is safe to use NextByte instead of NextChar here, even for
NextChar(p, plen); * multi-byte character sets, because we are not following
* immediately after a wildcard character.
* If we are in the middle of a multibyte character, we must
* already have matched at least one byte of the character from
* both text and pattern; so we cannot get out-of-sync
* on character boundaries. And we know that no backend-legal
* encoding allows ASCII characters such as '%' to appear as
* non-first bytes of characters, so we won't mistakenly detect
* a new wildcard.
*/
NextByte(t, tlen);
NextByte(p, plen);
} }
if (tlen > 0) if (tlen > 0)
@ -142,7 +213,8 @@ MatchText(char *t, int tlen, char *p, int plen)
/* End of input string. Do we have matching pattern remaining? */ /* End of input string. Do we have matching pattern remaining? */
while ((plen > 0) && (*p == '%')) /* allow multiple %'s at end of while ((plen > 0) && (*p == '%')) /* allow multiple %'s at end of
* pattern */ * pattern */
NextChar(p, plen); NextByte(p, plen);
if (plen <= 0) if (plen <= 0)
return LIKE_TRUE; return LIKE_TRUE;
@ -153,96 +225,12 @@ MatchText(char *t, int tlen, char *p, int plen)
return LIKE_ABORT; return LIKE_ABORT;
} /* MatchText() */ } /* MatchText() */
/*
* Same as above, but ignore case
*/
static int
MatchTextIC(char *t, int tlen, char *p, int plen)
{
/* Fast path for match-everything pattern */
if ((plen == 1) && (*p == '%'))
return LIKE_TRUE;
while ((tlen > 0) && (plen > 0))
{
if (*p == '\\')
{
/* Next pattern char must match literally, whatever it is */
NextChar(p, plen);
if ((plen <= 0) || !ICHAREQ(t, p))
return LIKE_FALSE;
}
else if (*p == '%')
{
/* %% is the same as % according to the SQL standard */
/* Advance past all %'s */
while ((plen > 0) && (*p == '%'))
NextChar(p, plen);
/* Trailing percent matches everything. */
if (plen <= 0)
return LIKE_TRUE;
/*
* Otherwise, scan for a text position at which we can match the
* rest of the pattern.
*/
while (tlen > 0)
{
/*
* Optimization to prevent most recursion: don't recurse
* unless first pattern char might match this text char.
*/
if (ICHAREQ(t, p) || (*p == '\\') || (*p == '_'))
{
int matched = MatchTextIC(t, tlen, p, plen);
if (matched != LIKE_FALSE)
return matched; /* TRUE or ABORT */
}
NextChar(t, tlen);
}
/*
* End of text with no match, so no point in trying later places
* to start matching this pattern.
*/
return LIKE_ABORT;
}
else if ((*p != '_') && !ICHAREQ(t, p))
{
/*
* Not the single-character wildcard and no explicit match? Then
* time to quit...
*/
return LIKE_FALSE;
}
NextChar(t, tlen);
NextChar(p, plen);
}
if (tlen > 0)
return LIKE_FALSE; /* end of pattern, but not of text */
/* End of input string. Do we have matching pattern remaining? */
while ((plen > 0) && (*p == '%')) /* allow multiple %'s at end of
* pattern */
NextChar(p, plen);
if (plen <= 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;
} /* MatchTextIC() */
/* /*
* like_escape() --- given a pattern and an ESCAPE string, * like_escape() --- given a pattern and an ESCAPE string,
* convert the pattern to use Postgres' standard backslash escape convention. * convert the pattern to use Postgres' standard backslash escape convention.
*/ */
#ifdef do_like_escape
static text * static text *
do_like_escape(text *pat, text *esc) do_like_escape(text *pat, text *esc)
{ {
@ -336,3 +324,17 @@ do_like_escape(text *pat, text *esc)
return result; return result;
} }
#endif /* do_like_escape */
#ifdef CHAREQ
#undef CHAREQ
#endif
#undef NextChar
#undef CopyAdvChar
#undef MatchText
#ifdef do_like_escape
#undef do_like_escape
#endif