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Back-patch fix for extraction of fixed prefixes from regular expressions.

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Back-patch of commits 628cbb50ba and
c6aae3042b.  This has been broken since
7.3, so back-patch to all supported branches.
This commit is contained in:
Tom Lane
2012-07-10 18:00:51 -04:00
parent b84da909d9
commit b9edaa784e
11 changed files with 429 additions and 208 deletions
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65
src/backend/utils/adt/regexp.c
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@ -1147,3 +1147,68 @@ build_regexp_split_result(regexp_matches_ctx *splitctx)
Int32GetDatum(startpos + 1));
}
}
/*
* regexp_fixed_prefix - extract fixed prefix, if any, for a regexp
*
* The result is NULL if there is no fixed prefix, else a palloc'd string.
* If it is an exact match, not just a prefix, *exact is returned as TRUE.
*/
char *
regexp_fixed_prefix(text *text_re, bool case_insensitive,
bool *exact)
{
char *result;
regex_t *re;
int cflags;
int re_result;
pg_wchar *str;
size_t slen;
size_t maxlen;
char errMsg[100];
*exact = false; /* default result */
/* Compile RE */
cflags = REG_ADVANCED;
if (case_insensitive)
cflags |= REG_ICASE;
re = RE_compile_and_cache(text_re, cflags);
/* Examine it to see if there's a fixed prefix */
re_result = pg_regprefix(re, &str, &slen);
switch (re_result)
{
case REG_NOMATCH:
return NULL;
case REG_PREFIX:
/* continue with wchar conversion */
break;
case REG_EXACT:
*exact = true;
/* continue with wchar conversion */
break;
default:
/* re failed??? */
pg_regerror(re_result, re, errMsg, sizeof(errMsg));
ereport(ERROR,
(errcode(ERRCODE_INVALID_REGULAR_EXPRESSION),
errmsg("regular expression failed: %s", errMsg)));
break;
}
/* Convert pg_wchar result back to database encoding */
maxlen = pg_database_encoding_max_length() * slen + 1;
result = (char *) palloc(maxlen);
slen = pg_wchar2mb_with_len(str, result, slen);
Assert(slen < maxlen);
free(str);
return result;
}