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diff --git a/src/backend/utils/adt/like_match.c b/src/backend/utils/adt/like_match.c
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+/*-------------------------------------------------------------------------
+ *
+ * like_match.c
+ * like expression handling internal code.
+ *
+ * This file is included by like.c *twice* if multibyte is enabled.
+ * This is for an optimization of single 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)
+ *
+ * Copyright (c) 1996-2001, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ * $Header: /cvsroot/pgsql/src/backend/utils/adt/like_match.c,v 1.1 2001/10/04 02:15:47 ishii Exp $
+ *
+ *-------------------------------------------------------------------------
+ */
+
+/*
+** Originally written by Rich $alz, mirror!rs, Wed Nov 26 19:03:17 EST 1986.
+** Rich $alz is now <[email protected]>.
+** Special thanks to Lars Mathiesen <[email protected]> for the LABORT code.
+**
+** This code was shamelessly stolen from the "pql" code by myself and
+** slightly modified :)
+**
+** All references to the word "star" were replaced by "percent"
+** All references to the word "wild" were replaced by "like"
+**
+** All the nice shell RE matching stuff was replaced by just "_" and "%"
+**
+** As I don't have a copy of the SQL standard handy I wasn't sure whether
+** to leave in the '\' escape character handling.
+**
+** Keith Parks. <[email protected]>
+**
+** 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
+**
+** 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...
+** - thomas 2000-08-06
+**
+*/
+
+
+/*--------------------
+ * 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
+MatchText(unsigned char *t, int tlen, unsigned 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) || !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 == '%'))
+ 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 (CHAREQ(t, p) || (*p == '\\') || (*p == '_'))
+ {
+ int matched = MatchText(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 != '_') && !CHAREQ(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;
+} /* MatchText() */
+
+/*
+ * Same as above, but ignore case
+ */
+static int
+MatchTextIC(unsigned char *t, int tlen, unsigned 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.
+ */
+static text *
+do_like_escape(text *pat, text *esc)
+{
+ text *result;
+ unsigned char *p,
+ *e,
+ *r;
+ int plen,
+ elen;
+ bool afterescape;
+
+ p = VARDATA(pat);
+ 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++ = '\\';
+ 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));
+ return 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;
+ }
+ }
+ }
+
+ VARATT_SIZEP(result) = r - ((unsigned char *) result);
+
+ return result;
+}
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