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Improve efficiency of LIKE/ILIKE code, especially for multi-byte charsets,
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
@ -11,7 +11,7 @@
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/src/backend/utils/adt/like.c,v 1.68 2007/02/27 23:48:08 tgl Exp $
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* $PostgreSQL: pgsql/src/backend/utils/adt/like.c,v 1.69 2007/06/02 02:03:42 adunstan Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -28,21 +28,23 @@
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#define LIKE_ABORT (-1)
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static int MatchText(char *t, int tlen, char *p, int plen);
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static int MatchTextIC(char *t, int tlen, char *p, int plen);
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static int MatchBytea(char *t, int tlen, char *p, int plen);
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static text *do_like_escape(text *, text *);
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static int SB_MatchText(char *t, int tlen, char *p, int plen);
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static text *SB_do_like_escape(text *, text *);
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static int MBMatchText(char *t, int tlen, char *p, int plen);
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static int MBMatchTextIC(char *t, int tlen, char *p, int plen);
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static int MB_MatchText(char *t, int tlen, char *p, int plen);
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static text *MB_do_like_escape(text *, text *);
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static int UTF8_MatchText(char *t, int tlen, char *p, int plen);
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static int GenericMatchText(char *s, int slen, char* p, int plen);
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static int Generic_Text_IC_like(text *str, text *pat);
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/*--------------------
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* Support routine for MatchText. Compares given multibyte streams
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* as wide characters. If they match, returns 1 otherwise returns 0.
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*--------------------
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*/
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static int
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static inline int
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wchareq(char *p1, char *p2)
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{
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int p1_len;
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@ -72,15 +74,12 @@ wchareq(char *p1, char *p2)
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* of getting a single character transformed to the system's wchar_t format.
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* So now, we just downcase the strings using lower() and apply regular LIKE
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* comparison. This should be revisited when we install better locale support.
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*
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* Note that MBMatchText and MBMatchTextIC do exactly the same thing now.
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* Is it worth refactoring to avoid duplicated code? They might become
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* different again in the future.
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*/
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#define NextByte(p, plen) ((p)++, (plen)--)
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/* Set up to compile like_match.c for multibyte characters */
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#define CHAREQ(p1, p2) wchareq(p1, p2)
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#define ICHAREQ(p1, p2) wchareq(p1, p2)
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#define CHAREQ(p1, p2) wchareq((p1), (p2))
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#define NextChar(p, plen) \
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do { int __l = pg_mblen(p); (p) +=__l; (plen) -=__l; } while (0)
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#define CopyAdvChar(dst, src, srclen) \
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@ -90,33 +89,59 @@ wchareq(char *p1, char *p2)
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*(dst)++ = *(src)++; \
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} while (0)
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#define MatchText MBMatchText
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#define MatchTextIC MBMatchTextIC
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#define MatchText MB_MatchText
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#define do_like_escape MB_do_like_escape
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#include "like_match.c"
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#undef CHAREQ
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#undef ICHAREQ
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#undef NextChar
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#undef CopyAdvChar
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#undef MatchText
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#undef MatchTextIC
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#undef do_like_escape
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/* Set up to compile like_match.c for single-byte characters */
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#define CHAREQ(p1, p2) (*(p1) == *(p2))
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#define ICHAREQ(p1, p2) (tolower((unsigned char) *(p1)) == tolower((unsigned char) *(p2)))
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#define NextChar(p, plen) ((p)++, (plen)--)
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#define NextChar(p, plen) NextByte((p), (plen))
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#define CopyAdvChar(dst, src, srclen) (*(dst)++ = *(src)++, (srclen)--)
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#define MatchText SB_MatchText
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#define do_like_escape SB_do_like_escape
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#include "like_match.c"
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/* And some support for BYTEA */
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#define BYTEA_CHAREQ(p1, p2) (*(p1) == *(p2))
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#define BYTEA_NextChar(p, plen) ((p)++, (plen)--)
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#define BYTEA_CopyAdvChar(dst, src, srclen) (*(dst)++ = *(src)++, (srclen)--)
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/* setup to compile like_match.c for UTF8 encoding, using fast NextChar */
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#define NextChar(p, plen) \
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do { (p)++; (plen)--; } while ((plen) > 0 && (*(p) & 0xC0) == 0x80 )
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#define MatchText UTF8_MatchText
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#include "like_match.c"
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static inline int
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GenericMatchText(char *s, int slen, char* p, int plen)
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{
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if (pg_database_encoding_max_length() == 1)
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return SB_MatchText(s, slen, p, plen);
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else if (GetDatabaseEncoding() == PG_UTF8)
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return UTF8_MatchText(s, slen, p, plen);
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else
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return MB_MatchText(s, slen, p, plen);
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}
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static inline int
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Generic_Text_IC_like(text *str, text *pat)
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{
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char *s,
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*p;
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int slen,
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plen;
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/* Force inputs to lower case to achieve case insensitivity */
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str = DatumGetTextP(DirectFunctionCall1(lower, PointerGetDatum(str)));
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pat = DatumGetTextP(DirectFunctionCall1(lower, PointerGetDatum(pat)));
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s = VARDATA(str);
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slen = (VARSIZE(str) - VARHDRSZ);
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p = VARDATA(pat);
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plen = (VARSIZE(pat) - VARHDRSZ);
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return GenericMatchText(s, slen, p, plen);
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}
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/*
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* interface routines called by the function manager
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@ -138,10 +163,7 @@ namelike(PG_FUNCTION_ARGS)
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p = VARDATA(pat);
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plen = (VARSIZE(pat) - VARHDRSZ);
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if (pg_database_encoding_max_length() == 1)
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result = (MatchText(s, slen, p, plen) == LIKE_TRUE);
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else
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result = (MBMatchText(s, slen, p, plen) == LIKE_TRUE);
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result = (GenericMatchText(s, slen, p, plen) == LIKE_TRUE);
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PG_RETURN_BOOL(result);
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}
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@ -162,10 +184,7 @@ namenlike(PG_FUNCTION_ARGS)
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p = VARDATA(pat);
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plen = (VARSIZE(pat) - VARHDRSZ);
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if (pg_database_encoding_max_length() == 1)
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result = (MatchText(s, slen, p, plen) != LIKE_TRUE);
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else
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result = (MBMatchText(s, slen, p, plen) != LIKE_TRUE);
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result = (GenericMatchText(s, slen, p, plen) != LIKE_TRUE);
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PG_RETURN_BOOL(result);
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}
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@ -186,10 +205,7 @@ textlike(PG_FUNCTION_ARGS)
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p = VARDATA(pat);
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plen = (VARSIZE(pat) - VARHDRSZ);
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if (pg_database_encoding_max_length() == 1)
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result = (MatchText(s, slen, p, plen) == LIKE_TRUE);
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else
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result = (MBMatchText(s, slen, p, plen) == LIKE_TRUE);
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result = (GenericMatchText(s, slen, p, plen) == LIKE_TRUE);
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PG_RETURN_BOOL(result);
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}
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@ -210,10 +226,7 @@ textnlike(PG_FUNCTION_ARGS)
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p = VARDATA(pat);
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plen = (VARSIZE(pat) - VARHDRSZ);
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if (pg_database_encoding_max_length() == 1)
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result = (MatchText(s, slen, p, plen) != LIKE_TRUE);
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else
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result = (MBMatchText(s, slen, p, plen) != LIKE_TRUE);
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result = (GenericMatchText(s, slen, p, plen) != LIKE_TRUE);
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PG_RETURN_BOOL(result);
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}
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@ -234,7 +247,7 @@ bytealike(PG_FUNCTION_ARGS)
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p = VARDATA(pat);
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plen = (VARSIZE(pat) - VARHDRSZ);
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result = (MatchBytea(s, slen, p, plen) == LIKE_TRUE);
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result = (SB_MatchText(s, slen, p, plen) == LIKE_TRUE);
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PG_RETURN_BOOL(result);
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}
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@ -255,7 +268,7 @@ byteanlike(PG_FUNCTION_ARGS)
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p = VARDATA(pat);
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plen = (VARSIZE(pat) - VARHDRSZ);
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result = (MatchBytea(s, slen, p, plen) != LIKE_TRUE);
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result = (SB_MatchText(s, slen, p, plen) != LIKE_TRUE);
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PG_RETURN_BOOL(result);
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}
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@ -270,37 +283,11 @@ nameiclike(PG_FUNCTION_ARGS)
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Name str = PG_GETARG_NAME(0);
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text *pat = PG_GETARG_TEXT_P(1);
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bool result;
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char *s,
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*p;
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int slen,
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plen;
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if (pg_database_encoding_max_length() == 1)
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{
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s = NameStr(*str);
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slen = strlen(s);
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p = VARDATA(pat);
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plen = (VARSIZE(pat) - VARHDRSZ);
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result = (MatchTextIC(s, slen, p, plen) == LIKE_TRUE);
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}
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else
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{
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/* Force inputs to lower case to achieve case insensitivity */
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text *strtext;
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strtext = DatumGetTextP(DirectFunctionCall1(name_text,
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NameGetDatum(str)));
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strtext = DatumGetTextP(DirectFunctionCall1(lower,
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PointerGetDatum(strtext)));
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pat = DatumGetTextP(DirectFunctionCall1(lower,
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PointerGetDatum(pat)));
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s = VARDATA(strtext);
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slen = (VARSIZE(strtext) - VARHDRSZ);
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p = VARDATA(pat);
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plen = (VARSIZE(pat) - VARHDRSZ);
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result = (MBMatchTextIC(s, slen, p, plen) == LIKE_TRUE);
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}
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result = (Generic_Text_IC_like(strtext, pat) == LIKE_TRUE);
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PG_RETURN_BOOL(result);
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}
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@ -311,37 +298,11 @@ nameicnlike(PG_FUNCTION_ARGS)
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Name str = PG_GETARG_NAME(0);
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text *pat = PG_GETARG_TEXT_P(1);
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bool result;
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char *s,
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*p;
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int slen,
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plen;
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if (pg_database_encoding_max_length() == 1)
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{
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s = NameStr(*str);
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slen = strlen(s);
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p = VARDATA(pat);
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plen = (VARSIZE(pat) - VARHDRSZ);
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result = (MatchTextIC(s, slen, p, plen) != LIKE_TRUE);
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}
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else
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{
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/* Force inputs to lower case to achieve case insensitivity */
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text *strtext;
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strtext = DatumGetTextP(DirectFunctionCall1(name_text,
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NameGetDatum(str)));
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strtext = DatumGetTextP(DirectFunctionCall1(lower,
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PointerGetDatum(strtext)));
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pat = DatumGetTextP(DirectFunctionCall1(lower,
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PointerGetDatum(pat)));
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s = VARDATA(strtext);
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slen = (VARSIZE(strtext) - VARHDRSZ);
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p = VARDATA(pat);
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plen = (VARSIZE(pat) - VARHDRSZ);
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result = (MBMatchTextIC(s, slen, p, plen) != LIKE_TRUE);
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}
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result = (Generic_Text_IC_like(strtext, pat) != LIKE_TRUE);
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PG_RETURN_BOOL(result);
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}
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@ -352,32 +313,8 @@ texticlike(PG_FUNCTION_ARGS)
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text *str = PG_GETARG_TEXT_P(0);
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text *pat = PG_GETARG_TEXT_P(1);
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bool result;
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char *s,
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*p;
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int slen,
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plen;
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if (pg_database_encoding_max_length() == 1)
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{
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s = VARDATA(str);
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slen = (VARSIZE(str) - VARHDRSZ);
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p = VARDATA(pat);
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plen = (VARSIZE(pat) - VARHDRSZ);
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result = (MatchTextIC(s, slen, p, plen) == LIKE_TRUE);
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}
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else
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{
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/* Force inputs to lower case to achieve case insensitivity */
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str = DatumGetTextP(DirectFunctionCall1(lower,
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PointerGetDatum(str)));
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pat = DatumGetTextP(DirectFunctionCall1(lower,
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PointerGetDatum(pat)));
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s = VARDATA(str);
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slen = (VARSIZE(str) - VARHDRSZ);
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p = VARDATA(pat);
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plen = (VARSIZE(pat) - VARHDRSZ);
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result = (MBMatchTextIC(s, slen, p, plen) == LIKE_TRUE);
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}
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result = (Generic_Text_IC_like(str, pat) == LIKE_TRUE);
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PG_RETURN_BOOL(result);
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}
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@ -388,32 +325,8 @@ texticnlike(PG_FUNCTION_ARGS)
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text *str = PG_GETARG_TEXT_P(0);
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text *pat = PG_GETARG_TEXT_P(1);
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bool result;
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char *s,
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*p;
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int slen,
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plen;
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if (pg_database_encoding_max_length() == 1)
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{
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s = VARDATA(str);
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slen = (VARSIZE(str) - VARHDRSZ);
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p = VARDATA(pat);
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plen = (VARSIZE(pat) - VARHDRSZ);
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result = (MatchTextIC(s, slen, p, plen) != LIKE_TRUE);
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}
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else
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{
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/* Force inputs to lower case to achieve case insensitivity */
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str = DatumGetTextP(DirectFunctionCall1(lower,
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PointerGetDatum(str)));
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pat = DatumGetTextP(DirectFunctionCall1(lower,
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PointerGetDatum(pat)));
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s = VARDATA(str);
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slen = (VARSIZE(str) - VARHDRSZ);
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p = VARDATA(pat);
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plen = (VARSIZE(pat) - VARHDRSZ);
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result = (MBMatchTextIC(s, slen, p, plen) != LIKE_TRUE);
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}
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result = (Generic_Text_IC_like(str, pat) != LIKE_TRUE);
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PG_RETURN_BOOL(result);
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}
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@ -430,7 +343,7 @@ like_escape(PG_FUNCTION_ARGS)
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text *result;
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if (pg_database_encoding_max_length() == 1)
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result = do_like_escape(pat, esc);
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result = SB_do_like_escape(pat, esc);
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else
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result = MB_do_like_escape(pat, esc);
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@ -446,179 +359,8 @@ like_escape_bytea(PG_FUNCTION_ARGS)
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{
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bytea *pat = PG_GETARG_BYTEA_P(0);
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bytea *esc = PG_GETARG_BYTEA_P(1);
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bytea *result;
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char *p,
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*e,
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*r;
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int plen,
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elen;
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bool afterescape;
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bytea *result = SB_do_like_escape((text *)pat, (text *)esc);
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p = VARDATA(pat);
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plen = (VARSIZE(pat) - VARHDRSZ);
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e = VARDATA(esc);
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elen = (VARSIZE(esc) - VARHDRSZ);
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/*
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* Worst-case pattern growth is 2x --- unlikely, but it's hardly worth
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* trying to calculate the size more accurately than that.
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*/
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result = (text *) palloc(plen * 2 + VARHDRSZ);
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r = VARDATA(result);
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if (elen == 0)
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{
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/*
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* No escape character is wanted. Double any backslashes in the
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* pattern to make them act like ordinary characters.
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*/
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while (plen > 0)
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{
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if (*p == '\\')
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*r++ = '\\';
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BYTEA_CopyAdvChar(r, p, plen);
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}
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}
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else
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{
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/*
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* The specified escape must be only a single character.
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*/
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BYTEA_NextChar(e, elen);
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if (elen != 0)
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ereport(ERROR,
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(errcode(ERRCODE_INVALID_ESCAPE_SEQUENCE),
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errmsg("invalid escape string"),
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errhint("Escape string must be empty or one character.")));
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e = VARDATA(esc);
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/*
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* If specified escape is '\', just copy the pattern as-is.
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*/
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if (*e == '\\')
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{
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memcpy(result, pat, VARSIZE(pat));
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PG_RETURN_BYTEA_P(result);
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PG_RETURN_BYTEA_P((bytea *)result);
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}
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/*
|
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* Otherwise, convert occurrences of the specified escape character to
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* '\', and double occurrences of '\' --- unless they immediately
|
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* follow an escape character!
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*/
|
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afterescape = false;
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while (plen > 0)
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{
|
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if (BYTEA_CHAREQ(p, e) && !afterescape)
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{
|
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*r++ = '\\';
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BYTEA_NextChar(p, plen);
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afterescape = true;
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}
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else if (*p == '\\')
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{
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*r++ = '\\';
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if (!afterescape)
|
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*r++ = '\\';
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BYTEA_NextChar(p, plen);
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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() */
|
||||
|
||||
@ -3,23 +3,21 @@
|
||||
* like_match.c
|
||||
* like expression handling internal code.
|
||||
*
|
||||
* This file is included by like.c *twice*, to provide an optimization
|
||||
* for single-byte encodings.
|
||||
* This file is included by like.c three times, to provide natching code for
|
||||
* 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:
|
||||
*
|
||||
* CHAREQ
|
||||
* ICHAREQ
|
||||
* NextChar
|
||||
* CopyAdvChar
|
||||
* MatchText (MBMatchText)
|
||||
* MatchTextIC (MBMatchTextIC)
|
||||
* do_like_escape (MB_do_like_escape)
|
||||
* MatchText - to name of function wanted
|
||||
* do_like_escape - name of function if wanted - needs CHAREQ and CopyAdvChar
|
||||
*
|
||||
* Copyright (c) 1996-2007, PostgreSQL Global Development Group
|
||||
*
|
||||
* 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 == '%'))
|
||||
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))
|
||||
{
|
||||
if (*p == '\\')
|
||||
{
|
||||
/* Next pattern char must match literally, whatever it is */
|
||||
NextChar(p, plen);
|
||||
if ((plen <= 0) || !CHAREQ(t, p))
|
||||
/* Next byte must match literally, whatever it is */
|
||||
NextByte(p, plen);
|
||||
if ((plen <= 0) || *p != *t )
|
||||
return LIKE_FALSE;
|
||||
}
|
||||
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 */
|
||||
/* Advance past all %'s */
|
||||
while ((plen > 0) && (*p == '%'))
|
||||
NextChar(p, plen);
|
||||
NextByte(p, plen);
|
||||
/* Trailing percent matches everything. */
|
||||
if (plen <= 0)
|
||||
return LIKE_TRUE;
|
||||
@ -100,13 +113,52 @@ MatchText(char *t, int tlen, char *p, int plen)
|
||||
* Otherwise, scan for a text position at which we can match the
|
||||
* rest of the pattern.
|
||||
*/
|
||||
if (*p == '_')
|
||||
|
||||
{
|
||||
/* %_ is the same as _% - avoid matching _ repeatedly */
|
||||
|
||||
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 char might match this text char.
|
||||
* unless first pattern byte matches first text byte.
|
||||
*/
|
||||
if (CHAREQ(t, p) || (*p == '\\') || (*p == '_'))
|
||||
if (*t == firstpat)
|
||||
{
|
||||
int matched = MatchText(t, tlen, p, plen);
|
||||
|
||||
@ -115,6 +167,8 @@ MatchText(char *t, int tlen, char *p, int plen)
|
||||
}
|
||||
|
||||
NextChar(t, tlen);
|
||||
|
||||
}
|
||||
}
|
||||
|
||||
/*
|
||||
@ -123,7 +177,13 @@ MatchText(char *t, int tlen, char *p, int plen)
|
||||
*/
|
||||
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
|
||||
@ -131,9 +191,20 @@ MatchText(char *t, int tlen, char *p, int plen)
|
||||
*/
|
||||
return LIKE_FALSE;
|
||||
}
|
||||
|
||||
NextChar(t, tlen);
|
||||
NextChar(p, plen);
|
||||
/*
|
||||
* It is safe to use NextByte instead of NextChar here, even for
|
||||
* 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)
|
||||
@ -142,7 +213,8 @@ MatchText(char *t, int tlen, char *p, int plen)
|
||||
/* End of input string. Do we have matching pattern remaining? */
|
||||
while ((plen > 0) && (*p == '%')) /* allow multiple %'s at end of
|
||||
* pattern */
|
||||
NextChar(p, plen);
|
||||
NextByte(p, plen);
|
||||
|
||||
if (plen <= 0)
|
||||
return LIKE_TRUE;
|
||||
|
||||
@ -153,96 +225,12 @@ MatchText(char *t, int tlen, char *p, int plen)
|
||||
return LIKE_ABORT;
|
||||
} /* 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,
|
||||
* convert the pattern to use Postgres' standard backslash escape convention.
|
||||
*/
|
||||
#ifdef do_like_escape
|
||||
|
||||
static text *
|
||||
do_like_escape(text *pat, text *esc)
|
||||
{
|
||||
@ -336,3 +324,17 @@ do_like_escape(text *pat, text *esc)
|
||||
|
||||
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
|
||||
|
||||
|
||||
Reference in New Issue
Block a user