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2ff501590b
Also performed an initial run through of upgrading our Copyright date to extend to 2005 ... first run here was very simple ... change everything where: grep 1996-2004 && the word 'Copyright' ... scanned through the generated list with 'less' first, and after, to make sure that I only picked up the right entries ...
339 lines
8.1 KiB
C
339 lines
8.1 KiB
C
/*-------------------------------------------------------------------------
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*
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* like_match.c
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* like expression handling internal code.
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*
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* This file is included by like.c *twice*, to provide an optimization
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* for single-byte encodings.
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*
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* Before the inclusion, we need to define following macros:
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*
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* CHAREQ
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* ICHAREQ
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* NextChar
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* CopyAdvChar
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* MatchText (MBMatchText)
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* MatchTextIC (MBMatchTextIC)
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* do_like_escape (MB_do_like_escape)
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*
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* Copyright (c) 1996-2005, PostgreSQL Global Development Group
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/src/backend/utils/adt/like_match.c,v 1.10 2004/12/31 22:01:22 pgsql Exp $
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*
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*-------------------------------------------------------------------------
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*/
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/*
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** Originally written by Rich $alz, mirror!rs, Wed Nov 26 19:03:17 EST 1986.
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** Rich $alz is now <rsalz@bbn.com>.
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** Special thanks to Lars Mathiesen <thorinn@diku.dk> for the LABORT code.
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**
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** This code was shamelessly stolen from the "pql" code by myself and
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** slightly modified :)
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**
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** All references to the word "star" were replaced by "percent"
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** All references to the word "wild" were replaced by "like"
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**
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** All the nice shell RE matching stuff was replaced by just "_" and "%"
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**
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** As I don't have a copy of the SQL standard handy I wasn't sure whether
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** to leave in the '\' escape character handling.
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**
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** Keith Parks. <keith@mtcc.demon.co.uk>
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**
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** SQL92 lets you specify the escape character by saying
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** LIKE <pattern> ESCAPE <escape character>. We are a small operation
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** so we force you to use '\'. - ay 7/95
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**
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** Now we have the like_escape() function that converts patterns with
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** any specified escape character (or none at all) to the internal
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** default escape character, which is still '\'. - tgl 9/2000
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**
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** The code is rewritten to avoid requiring null-terminated strings,
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** which in turn allows us to leave out some memcpy() operations.
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** This code should be faster and take less memory, but no promises...
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** - thomas 2000-08-06
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**
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*/
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/*--------------------
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* Match text and p, return LIKE_TRUE, LIKE_FALSE, or LIKE_ABORT.
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*
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* LIKE_TRUE: they match
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* LIKE_FALSE: they don't match
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* LIKE_ABORT: not only don't they match, but the text is too short.
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*
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* If LIKE_ABORT is returned, then no suffix of the text can match the
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* pattern either, so an upper-level % scan can stop scanning now.
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*--------------------
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*/
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static int
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MatchText(unsigned char *t, int tlen, unsigned char *p, int plen)
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{
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/* Fast path for match-everything pattern */
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if ((plen == 1) && (*p == '%'))
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return LIKE_TRUE;
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while ((tlen > 0) && (plen > 0))
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{
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if (*p == '\\')
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{
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/* Next pattern char must match literally, whatever it is */
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NextChar(p, plen);
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if ((plen <= 0) || !CHAREQ(t, p))
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return LIKE_FALSE;
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}
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else if (*p == '%')
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{
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/* %% is the same as % according to the SQL standard */
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/* Advance past all %'s */
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while ((plen > 0) && (*p == '%'))
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NextChar(p, plen);
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/* Trailing percent matches everything. */
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if (plen <= 0)
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return LIKE_TRUE;
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/*
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* Otherwise, scan for a text position at which we can match
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* the rest of the pattern.
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*/
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while (tlen > 0)
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{
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/*
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* Optimization to prevent most recursion: don't recurse
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* unless first pattern char might match this text char.
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*/
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if (CHAREQ(t, p) || (*p == '\\') || (*p == '_'))
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{
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int matched = MatchText(t, tlen, p, plen);
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if (matched != LIKE_FALSE)
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return matched; /* TRUE or ABORT */
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}
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NextChar(t, tlen);
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}
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/*
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* End of text with no match, so no point in trying later
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* places to start matching this pattern.
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*/
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return LIKE_ABORT;
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}
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else if ((*p != '_') && !CHAREQ(t, p))
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{
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/*
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* Not the single-character wildcard and no explicit match?
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* Then time to quit...
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*/
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return LIKE_FALSE;
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}
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NextChar(t, tlen);
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NextChar(p, plen);
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}
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if (tlen > 0)
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return LIKE_FALSE; /* end of pattern, but not of text */
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/* End of input string. Do we have matching pattern remaining? */
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while ((plen > 0) && (*p == '%')) /* allow multiple %'s at end of
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* pattern */
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NextChar(p, plen);
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if (plen <= 0)
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return LIKE_TRUE;
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/*
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* End of text with no match, so no point in trying later places to
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* start matching this pattern.
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*/
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return LIKE_ABORT;
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} /* MatchText() */
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/*
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* Same as above, but ignore case
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*/
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static int
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MatchTextIC(unsigned char *t, int tlen, unsigned char *p, int plen)
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{
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/* Fast path for match-everything pattern */
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if ((plen == 1) && (*p == '%'))
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return LIKE_TRUE;
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while ((tlen > 0) && (plen > 0))
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{
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if (*p == '\\')
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{
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/* Next pattern char must match literally, whatever it is */
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NextChar(p, plen);
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if ((plen <= 0) || !ICHAREQ(t, p))
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return LIKE_FALSE;
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}
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else if (*p == '%')
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{
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/* %% is the same as % according to the SQL standard */
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/* Advance past all %'s */
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while ((plen > 0) && (*p == '%'))
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NextChar(p, plen);
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/* Trailing percent matches everything. */
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if (plen <= 0)
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return LIKE_TRUE;
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/*
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* Otherwise, scan for a text position at which we can match
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* the rest of the pattern.
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*/
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while (tlen > 0)
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{
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/*
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* Optimization to prevent most recursion: don't recurse
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* unless first pattern char might match this text char.
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*/
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if (ICHAREQ(t, p) || (*p == '\\') || (*p == '_'))
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{
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int matched = MatchTextIC(t, tlen, p, plen);
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if (matched != LIKE_FALSE)
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return matched; /* TRUE or ABORT */
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}
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NextChar(t, tlen);
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}
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/*
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* End of text with no match, so no point in trying later
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* places to start matching this pattern.
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*/
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return LIKE_ABORT;
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}
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else if ((*p != '_') && !ICHAREQ(t, p))
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{
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/*
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* Not the single-character wildcard and no explicit match?
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* Then time to quit...
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*/
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return LIKE_FALSE;
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}
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NextChar(t, tlen);
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NextChar(p, plen);
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}
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if (tlen > 0)
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return LIKE_FALSE; /* end of pattern, but not of text */
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/* End of input string. Do we have matching pattern remaining? */
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while ((plen > 0) && (*p == '%')) /* allow multiple %'s at end of
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* pattern */
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NextChar(p, plen);
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if (plen <= 0)
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return LIKE_TRUE;
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/*
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* End of text with no match, so no point in trying later places to
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* start matching this pattern.
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*/
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return LIKE_ABORT;
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} /* MatchTextIC() */
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/*
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* like_escape() --- given a pattern and an ESCAPE string,
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* convert the pattern to use Postgres' standard backslash escape convention.
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*/
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static text *
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do_like_escape(text *pat, text *esc)
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{
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text *result;
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unsigned 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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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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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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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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return result;
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}
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/*
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* Otherwise, convert occurrences of the specified escape
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* character to '\', and double occurrences of '\' --- unless they
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* immediately 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 (CHAREQ(p, e) && !afterescape)
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{
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*r++ = '\\';
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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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NextChar(p, plen);
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afterescape = false;
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}
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else
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{
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CopyAdvChar(r, p, plen);
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afterescape = false;
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}
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}
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}
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VARATT_SIZEP(result) = r - ((unsigned char *) result);
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return result;
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}
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