Reimplement LIKE/ESCAPE as operators so that indexscan optimization

can still work, per recent discussion on pghackers.  Correct some bugs
in ILIKE implementation.

1 files changed, 207 insertions, 284 deletions

diff --git a/src/backend/utils/adt/like.c b/src/backend/utils/adt/like.c
index e492c58cbad..41e86648b87 100644
--- a/src/backend/utils/adt/like.c
+++ b/src/backend/utils/adt/like.c
@@ -11,12 +11,14 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	$Header: /cvsroot/pgsql/src/backend/utils/adt/like.c,v 1.41 2000/08/22 06:33:57 ishii Exp $
+ *	$Header: /cvsroot/pgsql/src/backend/utils/adt/like.c,v 1.42 2000/09/15 18:45:26 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
 #include "postgres.h"
+
 #include <ctype.h>
+
 #ifdef MULTIBYTE
 #include "mb/pg_wchar.h"
 #endif
@@ -28,92 +30,129 @@
 #define LIKE_ABORT						(-1)
 
 
-static int MatchText(unsigned char * t, int tlen, unsigned char * p, int plen, char *e);
-static int MatchTextLower(unsigned char * t, int tlen, unsigned char * p, int plen, char *e);
+static int MatchText(unsigned char * t, int tlen,
+					 unsigned char * p, int plen);
+static int MatchTextIC(unsigned char * t, int tlen,
+					   unsigned char * p, int plen);
 
 
-/*
- *	interface routines called by the function manager
+#ifdef MULTIBYTE
+/*--------------------
+ * Support routine for MatchText. Compares given multibyte streams
+ * as wide characters. If they match, returns 1 otherwise returns 0.
+ *--------------------
  */
-
-Datum
-namelike(PG_FUNCTION_ARGS)
+static int wchareq(unsigned char *p1, unsigned char *p2)
 {
-	bool		result;
-	Name		str = PG_GETARG_NAME(0);
-	text	   *pat = PG_GETARG_TEXT_P(1);
-	unsigned char   *s, *p;
-	int			slen, plen;
+	int l;
 
-	s = NameStr(*str);
-	slen = strlen(s);
-	p = VARDATA(pat);
-	plen = (VARSIZE(pat)-VARHDRSZ);
+	l = pg_mblen(p1);
+	if (pg_mblen(p2) != l) {
+		return(0);
+	}
+	while (l--) {
+		if (*p1++ != *p2++)
+			return(0);
+	}
+	return(1);
+}
 
-	result = (MatchText(s, slen, p, plen, "\\") == LIKE_TRUE);
+/*--------------------
+ * Support routine for MatchTextIC. Compares given multibyte streams
+ * as wide characters ignoring case.
+ * If they match, returns 1 otherwise returns 0.
+ *--------------------
+ */
+#define UCHARMAX 0xff
 
-	PG_RETURN_BOOL(result);
+static int iwchareq(unsigned char *p1, unsigned char *p2)
+{
+	int c1, c2;
+	int l;
+
+	/* short cut. if *p1 and *p2 is lower than UCHARMAX, then
+	   we assume they are ASCII */
+	if (*p1 < UCHARMAX && *p2 < UCHARMAX)
+		return(tolower(*p1) == tolower(*p2));
+
+	if (*p1 < UCHARMAX)
+		c1 = tolower(*p1);
+	else
+	{
+		l = pg_mblen(p1);
+		(void)pg_mb2wchar_with_len(p1, (pg_wchar *)&c1, l);
+		c1 = tolower(c1);
+	}
+	if (*p2 < UCHARMAX)
+		c2 = tolower(*p2);
+	else
+	{
+		l = pg_mblen(p2);
+		(void)pg_mb2wchar_with_len(p2, (pg_wchar *)&c2, l);
+		c2 = tolower(c2);
+	}
+	return(c1 == c2);
 }
 
-Datum
-namenlike(PG_FUNCTION_ARGS)
-{
-	bool		result;
-	Name		str = PG_GETARG_NAME(0);
-	text	   *pat = PG_GETARG_TEXT_P(1);
-	unsigned char   *s, *p;
-	int			slen, plen;
+#endif
 
-	s = NameStr(*str);
-	slen = strlen(s);
-	p = VARDATA(pat);
-	plen = (VARSIZE(pat)-VARHDRSZ);
+#ifdef MULTIBYTE
+#define CHAREQ(p1, p2) wchareq(p1, p2)
+#define ICHAREQ(p1, p2) iwchareq(p1, p2)
+#define NextChar(p, plen) \
+	do { int __l = pg_mblen(p); (p) +=__l; (plen) -=__l; } while (0)
+#define CopyAdvChar(dst, src, srclen) \
+	do { int __l = pg_mblen(src); \
+		 (srclen) -= __l; \
+		 while (__l-- > 0) \
+			 *(dst)++ = *(src)++; \
+	   } while (0)
+#else
+#define CHAREQ(p1, p2) (*(p1) == *(p2))
+#define ICHAREQ(p1, p2) (tolower(*(p1)) == tolower(*(p2)))
+#define NextChar(p, plen) ((p)++, (plen)--)
+#define CopyAdvChar(dst, src, srclen) (*(dst)++ = *(src)++, (srclen)--)
+#endif
 
-	result = (MatchText(s, slen, p, plen, "\\") != LIKE_TRUE);
 
-	PG_RETURN_BOOL(result);
-}
+/*
+ *	interface routines called by the function manager
+ */
 
 Datum
-namelike_escape(PG_FUNCTION_ARGS)
+namelike(PG_FUNCTION_ARGS)
 {
-	bool		result;
 	Name		str = PG_GETARG_NAME(0);
 	text	   *pat = PG_GETARG_TEXT_P(1);
-	text	   *esc = PG_GETARG_TEXT_P(2);
+	bool		result;
 	unsigned char   *s, *p;
 	int			slen, plen;
-	char	   *e;
 
 	s = NameStr(*str);
 	slen = strlen(s);
 	p = VARDATA(pat);
 	plen = (VARSIZE(pat)-VARHDRSZ);
-	e = ((VARSIZE(esc)-VARHDRSZ) > 0? VARDATA(esc): NULL);
 
-	result = (MatchText(s, slen, p, plen, e) == LIKE_TRUE);
+	result = (MatchText(s, slen, p, plen) == LIKE_TRUE);
 
 	PG_RETURN_BOOL(result);
 }
 
 Datum
-namenlike_escape(PG_FUNCTION_ARGS)
+namenlike(PG_FUNCTION_ARGS)
 {
-	bool		result;
 	Name		str = PG_GETARG_NAME(0);
 	text	   *pat = PG_GETARG_TEXT_P(1);
-	text	   *esc = PG_GETARG_TEXT_P(2);
+	bool		result;
 	unsigned char   *s, *p;
 	int			slen, plen;
-	char	   *e;
 
 	s = NameStr(*str);
 	slen = strlen(s);
 	p = VARDATA(pat);
 	plen = (VARSIZE(pat)-VARHDRSZ);
-	e = ((VARSIZE(esc)-VARHDRSZ) > 0? VARDATA(esc): NULL);
 
-	result = (MatchText(s, slen, p, plen, e) != LIKE_TRUE);
+	result = (MatchText(s, slen, p, plen) != LIKE_TRUE);
 
 	PG_RETURN_BOOL(result);
 }
@@ -121,28 +160,9 @@ namenlike_escape(PG_FUNCTION_ARGS)
 Datum
 textlike(PG_FUNCTION_ARGS)
 {
-	bool		result;
 	text	   *str = PG_GETARG_TEXT_P(0);
 	text	   *pat = PG_GETARG_TEXT_P(1);
-	unsigned char   *s, *p;
-	int			slen, plen;
-
-	s = VARDATA(str);
-	slen = (VARSIZE(str)-VARHDRSZ);
-	p = VARDATA(pat);
-	plen = (VARSIZE(pat)-VARHDRSZ);
-
-	result = (MatchText(s, slen, p, plen, NULL) == LIKE_TRUE);
-
-	PG_RETURN_BOOL(result);
-}
-
-Datum
-textnlike(PG_FUNCTION_ARGS)
-{
 	bool		result;
-	text	   *str = PG_GETARG_TEXT_P(0);
-	text	   *pat = PG_GETARG_TEXT_P(1);
 	unsigned char   *s, *p;
 	int			slen, plen;
 
@@ -151,51 +171,26 @@ textnlike(PG_FUNCTION_ARGS)
 	p = VARDATA(pat);
 	plen = (VARSIZE(pat)-VARHDRSZ);
 
-	result = (MatchText(s, slen, p, plen, "\\") != LIKE_TRUE);
+	result = (MatchText(s, slen, p, plen) == LIKE_TRUE);
 
 	PG_RETURN_BOOL(result);
 }
 
 Datum
-textlike_escape(PG_FUNCTION_ARGS)
+textnlike(PG_FUNCTION_ARGS)
 {
-	bool		result;
 	text	   *str = PG_GETARG_TEXT_P(0);
 	text	   *pat = PG_GETARG_TEXT_P(1);
-	text	   *esc = PG_GETARG_TEXT_P(2);
-	unsigned char   *s, *p;
-	int			slen, plen;
-	char	   *e;
-
-	s = VARDATA(str);
-	slen = (VARSIZE(str)-VARHDRSZ);
-	p = VARDATA(pat);
-	plen = (VARSIZE(pat)-VARHDRSZ);
-	e = ((VARSIZE(esc)-VARHDRSZ) > 0? VARDATA(esc): NULL);
-
-	result = (MatchText(s, slen, p, plen, e) == LIKE_TRUE);
-
-	PG_RETURN_BOOL(result);
-}
-
-Datum
-textnlike_escape(PG_FUNCTION_ARGS)
-{
 	bool		result;
-	text	   *str = PG_GETARG_TEXT_P(0);
-	text	   *pat = PG_GETARG_TEXT_P(1);
-	text	   *esc = PG_GETARG_TEXT_P(2);
 	unsigned char   *s, *p;
 	int			slen, plen;
-	char	   *e;
 
 	s = VARDATA(str);
 	slen = (VARSIZE(str)-VARHDRSZ);
 	p = VARDATA(pat);
 	plen = (VARSIZE(pat)-VARHDRSZ);
-	e = ((VARSIZE(esc)-VARHDRSZ) > 0? VARDATA(esc): NULL);
 
-	result = (MatchText(s, slen, p, plen, e) != LIKE_TRUE);
+	result = (MatchText(s, slen, p, plen) != LIKE_TRUE);
 
 	PG_RETURN_BOOL(result);
 }
@@ -205,30 +200,11 @@ textnlike_escape(PG_FUNCTION_ARGS)
  */
 
 Datum
-inamelike(PG_FUNCTION_ARGS)
+nameiclike(PG_FUNCTION_ARGS)
 {
-	bool		result;
 	Name		str = PG_GETARG_NAME(0);
 	text	   *pat = PG_GETARG_TEXT_P(1);
-	unsigned char   *s, *p;
-	int			slen, plen;
-
-	s = NameStr(*str);
-	slen = strlen(s);
-	p = VARDATA(pat);
-	plen = (VARSIZE(pat)-VARHDRSZ);
-
-	result = (MatchTextLower(s, slen, p, plen, "\\") == LIKE_TRUE);
-
-	PG_RETURN_BOOL(result);
-}
-
-Datum
-inamenlike(PG_FUNCTION_ARGS)
-{
 	bool		result;
-	Name		str = PG_GETARG_NAME(0);
-	text	   *pat = PG_GETARG_TEXT_P(1);
 	unsigned char   *s, *p;
 	int			slen, plen;
 
@@ -237,61 +213,36 @@ inamenlike(PG_FUNCTION_ARGS)
 	p = VARDATA(pat);
 	plen = (VARSIZE(pat)-VARHDRSZ);
 
-	result = (MatchTextLower(s, slen, p, plen, "\\") != LIKE_TRUE);
+	result = (MatchTextIC(s, slen, p, plen) == LIKE_TRUE);
 
 	PG_RETURN_BOOL(result);
 }
 
 Datum
-inamelike_escape(PG_FUNCTION_ARGS)
+nameicnlike(PG_FUNCTION_ARGS)
 {
-	bool		result;
 	Name		str = PG_GETARG_NAME(0);
 	text	   *pat = PG_GETARG_TEXT_P(1);
-	text	   *esc = PG_GETARG_TEXT_P(2);
-	unsigned char   *s, *p;
-	int			slen, plen;
-	char	   *e;
-
-	s = NameStr(*str);
-	slen = strlen(s);
-	p = VARDATA(pat);
-	plen = (VARSIZE(pat)-VARHDRSZ);
-	e = ((VARSIZE(esc)-VARHDRSZ) > 0? VARDATA(esc): NULL);
-
-	result = (MatchTextLower(s, slen, p, plen, e) == LIKE_TRUE);
-
-	PG_RETURN_BOOL(result);
-}
-
-Datum
-inamenlike_escape(PG_FUNCTION_ARGS)
-{
 	bool		result;
-	Name		str = PG_GETARG_NAME(0);
-	text	   *pat = PG_GETARG_TEXT_P(1);
-	text	   *esc = PG_GETARG_TEXT_P(2);
 	unsigned char   *s, *p;
 	int			slen, plen;
-	char	   *e;
 
 	s = NameStr(*str);
 	slen = strlen(s);
 	p = VARDATA(pat);
 	plen = (VARSIZE(pat)-VARHDRSZ);
-	e = ((VARSIZE(esc)-VARHDRSZ) > 0? VARDATA(esc): NULL);
 
-	result = (MatchTextLower(s, slen, p, plen, e) != LIKE_TRUE);
+	result = (MatchTextIC(s, slen, p, plen) != LIKE_TRUE);
 
 	PG_RETURN_BOOL(result);
 }
 
 Datum
-itextlike(PG_FUNCTION_ARGS)
+texticlike(PG_FUNCTION_ARGS)
 {
-	bool		result;
 	text	   *str = PG_GETARG_TEXT_P(0);
 	text	   *pat = PG_GETARG_TEXT_P(1);
+	bool		result;
 	unsigned char   *s, *p;
 	int			slen, plen;
 
@@ -300,17 +251,17 @@ itextlike(PG_FUNCTION_ARGS)
 	p = VARDATA(pat);
 	plen = (VARSIZE(pat)-VARHDRSZ);
 
-	result = (MatchTextLower(s, slen, p, plen, "\\") == LIKE_TRUE);
+	result = (MatchTextIC(s, slen, p, plen) == LIKE_TRUE);
 
 	PG_RETURN_BOOL(result);
 }
 
 Datum
-itextnlike(PG_FUNCTION_ARGS)
+texticnlike(PG_FUNCTION_ARGS)
 {
-	bool		result;
 	text	   *str = PG_GETARG_TEXT_P(0);
 	text	   *pat = PG_GETARG_TEXT_P(1);
+	bool		result;
 	unsigned char   *s, *p;
 	int			slen, plen;
 
@@ -319,53 +270,100 @@ itextnlike(PG_FUNCTION_ARGS)
 	p = VARDATA(pat);
 	plen = (VARSIZE(pat)-VARHDRSZ);
 
-	result = (MatchTextLower(s, slen, p, plen, "\\") != LIKE_TRUE);
+	result = (MatchTextIC(s, slen, p, plen) != LIKE_TRUE);
 
 	PG_RETURN_BOOL(result);
 }
 
+/*
+ * like_escape() --- given a pattern and an ESCAPE string,
+ * convert the pattern to use Postgres' standard backslash escape convention.
+ */
 Datum
-itextlike_escape(PG_FUNCTION_ARGS)
+like_escape(PG_FUNCTION_ARGS)
 {
-	bool		result;
-	text	   *str = PG_GETARG_TEXT_P(0);
-	text	   *pat = PG_GETARG_TEXT_P(1);
-	text	   *esc = PG_GETARG_TEXT_P(2);
-	unsigned char   *s, *p;
-	int			slen, plen;
-	char	   *e;
+	text	   *pat = PG_GETARG_TEXT_P(0);
+	text	   *esc = PG_GETARG_TEXT_P(1);
+	text	   *result;
+	unsigned char   *p, *e, *r;
+	int			plen, elen;
+	bool		afterescape;
 
-	s = VARDATA(str);
-	slen = (VARSIZE(str)-VARHDRSZ);
 	p = VARDATA(pat);
 	plen = (VARSIZE(pat)-VARHDRSZ);
-	e = ((VARSIZE(esc)-VARHDRSZ) > 0? VARDATA(esc): NULL);
-
-	result = (MatchTextLower(s, slen, p, plen, e) == LIKE_TRUE);
+	e = VARDATA(esc);
+	elen = (VARSIZE(esc)-VARHDRSZ);
 
-	PG_RETURN_BOOL(result);
-}
-
-Datum
-itextnlike_escape(PG_FUNCTION_ARGS)
-{
-	bool		result;
-	text	   *str = PG_GETARG_TEXT_P(0);
-	text	   *pat = PG_GETARG_TEXT_P(1);
-	text	   *esc = PG_GETARG_TEXT_P(2);
-	unsigned char   *s, *p;
-	int			slen, plen;
-	char	   *e;
+	/*
+	 * 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);
 
-	s = VARDATA(str);
-	slen = (VARSIZE(str)-VARHDRSZ);
-	p = VARDATA(pat);
-	plen = (VARSIZE(pat)-VARHDRSZ);
-	e = ((VARSIZE(esc)-VARHDRSZ) > 0? VARDATA(esc): NULL);
+	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++ = '\\';
+			CopyAdvChar(r, p, plen);
+		}
+	}
+	else
+	{
+		/*
+		 * The specified escape must be only a single character.
+		 */
+		NextChar(e, elen);
+		if (elen != 0)
+			elog(ERROR, "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_TEXT_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 (CHAREQ(p,e) && !afterescape)
+			{
+				*r++ = '\\';
+				NextChar(p, plen);
+				afterescape = true;
+			}
+			else if (*p == '\\')
+			{
+				*r++ = '\\';
+				if (! afterescape)
+					*r++ = '\\';
+				NextChar(p, plen);
+				afterescape = false;
+			}
+			else
+			{
+				CopyAdvChar(r, p, plen);
+				afterescape = false;
+			}
+		}
+	}
 
-	result = (MatchTextLower(s, slen, p, plen, e) != LIKE_TRUE);
+	VARATT_SIZEP(result) = r - ((unsigned char *) result);
 
-	PG_RETURN_BOOL(result);
+	PG_RETURN_TEXT_P(result);
 }
 
 
@@ -387,13 +385,14 @@ itextnlike_escape(PG_FUNCTION_ARGS)
 **
 **	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]
+**	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
+**
+**	Now we have the like_escape() function that converts patterns with
+**	any specified escape character (or none at all) to the internal
+**	default escape character, which is still '\'. - tgl 9/2000
 **
-** OK, we now support the SQL9x LIKE <pattern> ESCAPE <char> syntax.
-** We should kill the backslash escaping mechanism since it is non-standard
-** and undocumented afaik.
 ** The code is rewritten to avoid requiring null-terminated strings,
 ** which in turn allows us to leave out some memcpy() operations.
 ** This code should be faster and take less memory, but no promises...
@@ -401,6 +400,7 @@ itextnlike_escape(PG_FUNCTION_ARGS)
 **
 */
 
+
 /*--------------------
  *	Match text and p, return LIKE_TRUE, LIKE_FALSE, or LIKE_ABORT.
  *
@@ -413,93 +413,18 @@ itextnlike_escape(PG_FUNCTION_ARGS)
  *--------------------
  */
 
-#ifdef MULTIBYTE
-/*--------------------
- * Support routine for MatchText. Compares given multibyte streams
- * as wide characters. If they match, returns 1 otherwise returns 0.
- *--------------------
- */
-static int wchareq(unsigned char *p1, unsigned char *p2)
-{
-	int l;
-
-	l = pg_mblen(p1);
-	if (pg_mblen(p2) != l) {
-		return(0);
-	}
-	while (l--) {
-		if (*p1++ != *p2++)
-			return(0);
-	}
-	return(1);
-}
-
-/*--------------------
- * Support routine for MatchTextLower. Compares given multibyte streams
- * as wide characters ignoring case.
- * If they match, returns 1 otherwise returns 0.
- *--------------------
- */
-#define UCHARMAX 0xff
-
-static int iwchareq(unsigned char *p1, unsigned char *p2)
-{
-	int c1, c2;
-	int l;
-
-	/* short cut. if *p1 and *p2 is lower than UCHARMAX, then
-	   we assume they are ASCII */
-	if (*p1 < UCHARMAX && *p2 < UCHARMAX)
-		return(tolower(*p1) == tolower(*p2));
-
-	if (*p1 < UCHARMAX)
-		c1 = tolower(*p1);
-	else
-	{
-		l = pg_mblen(p1);
-		(void)pg_mb2wchar_with_len(p1, (pg_wchar *)&c1, l);
-		c1 = tolower(c1);
-	}
-	if (*p2 < UCHARMAX)
-		c2 = tolower(*p2);
-	else
-	{
-		l = pg_mblen(p2);
-		(void)pg_mb2wchar_with_len(p2, (pg_wchar *)&c2, l);
-		c2 = tolower(c2);
-	}
-	return(c1 == c2);
-}
-#endif
-
-#ifdef MULTIBYTE
-#define CHAREQ(p1, p2) wchareq(p1, p2)
-#define ICHAREQ(p1, p2) iwchareq(p1, p2)
-#define NextChar(p, plen) {int __l = pg_mblen(p); (p) +=__l; (plen) -=__l;}
-#else
-#define CHAREQ(p1, p2) (*(p1) == *(p2))
-#define ICHAREQ(p1, p2) (tolower(*(p1)) == tolower(*(p2)))
-#define NextChar(p, plen) (p)++, (plen)--
-#endif
-
 static int
-MatchText(unsigned char * t, int tlen, unsigned char * p, int plen, char *e)
+MatchText(unsigned char * t, int tlen, unsigned char * p, int plen)
 {
-	/* Fast path for match-everything pattern
-	 * Include weird case of escape character as a percent sign or underscore,
-	 * when presumably that wildcard character becomes a literal.
-	 */
-	if ((plen == 1) && (*p == '%')
-		&& ! ((e != NULL) && (*e == '%')))
+	/* Fast path for match-everything pattern */
+	if ((plen == 1) && (*p == '%'))
 		return LIKE_TRUE;
 
 	while ((tlen > 0) && (plen > 0))
 	{
-		/* If an escape character was specified and we find it here in the pattern,
-		 * then we'd better have an exact match for the next character.
-		 */
-		if ((e != NULL) && CHAREQ(p,e))
+		if (*p == '\\')
 		{
+			/* Next pattern char must match literally, whatever it is */
 			NextChar(p, plen);
 			if ((plen <= 0) || !CHAREQ(t,p))
 				return LIKE_FALSE;
@@ -525,10 +450,9 @@ MatchText(unsigned char * t, int tlen, unsigned char * p, int plen, char *e)
 				 * recurse unless first pattern char might match this
 				 * text char.
 				 */
-				if (CHAREQ(t,p) || (*p == '_')
-					|| ((e != NULL) && CHAREQ(p,e)))
+				if (CHAREQ(t,p) || (*p == '\\')  || (*p == '_'))
 				{
-					int matched = MatchText(t, tlen, p, plen, e);
+					int matched = MatchText(t, tlen, p, plen);
 
 					if (matched != LIKE_FALSE)
 						return matched;		/* TRUE or ABORT */
@@ -571,24 +495,21 @@ MatchText(unsigned char * t, int tlen, unsigned char * p, int plen, char *e)
 	return LIKE_ABORT;
 } /* MatchText() */
 
+/*
+ * Same as above, but ignore case
+ */
 static int
-MatchTextLower(unsigned char * t, int tlen, unsigned char * p, int plen, char *e)
+MatchTextIC(unsigned char * t, int tlen, unsigned char * p, int plen)
 {
-	/* Fast path for match-everything pattern
-	 * Include weird case of escape character as a percent sign or underscore,
-	 * when presumably that wildcard character becomes a literal.
-	 */
-	if ((plen == 1) && (*p == '%')
-		&& ! ((e != NULL) && (*e == '%')))
+	/* Fast path for match-everything pattern */
+	if ((plen == 1) && (*p == '%'))
 		return LIKE_TRUE;
 
 	while ((tlen > 0) && (plen > 0))
 	{
-		/* If an escape character was specified and we find it here in the pattern,
-		 * then we'd better have an exact match for the next character.
-		 */
-		if ((e != NULL) && ICHAREQ(p,e))
+		if (*p == '\\')
 		{
+			/* Next pattern char must match literally, whatever it is */
 			NextChar(p, plen);
 			if ((plen <= 0) || !ICHAREQ(t,p))
 				return LIKE_FALSE;
@@ -614,10 +535,9 @@ MatchTextLower(unsigned char * t, int tlen, unsigned char * p, int plen, char *e
 				 * recurse unless first pattern char might match this
 				 * text char.
 				 */
-				if (ICHAREQ(t,p) || (*p == '_')
-					|| ((e != NULL) && ICHAREQ(p,e)))
+				if (ICHAREQ(t,p) || (*p == '\\')  || (*p == '_'))
 				{
-					int matched = MatchText(t, tlen, p, plen, e);
+					int matched = MatchTextIC(t, tlen, p, plen);
 
 					if (matched != LIKE_FALSE)
 						return matched;		/* TRUE or ABORT */
@@ -634,6 +554,9 @@ MatchTextLower(unsigned char * t, int tlen, unsigned char * p, int plen, char *e
 		}
 		else if ((*p != '_') && !ICHAREQ(t,p))
 		{
+			/* Not the single-character wildcard and no explicit match?
+			 * Then time to quit...
+			 */
 			return LIKE_FALSE;
 		}
 
@@ -655,4 +578,4 @@ MatchTextLower(unsigned char * t, int tlen, unsigned char * p, int plen, char *e
 	 * start matching this pattern.
 	 */
 	return LIKE_ABORT;
-} /* MatchTextLower() */
+} /* MatchTextIC() */