Remove regex_flavor GUC, so that regular expressions are always "advanced"

style by default.  Per discussion, there seems to be hardly anything that
really relies on being able to change the regex flavor, so the ability to
select it via embedded options ought to be enough for any stragglers.
Also, if we didn't remove the GUC, we'd really be morally obligated to
mark the regex functions non-immutable, which'd possibly create performance
issues.

1 files changed, 10 insertions, 22 deletions

diff --git a/src/backend/utils/adt/selfuncs.c b/src/backend/utils/adt/selfuncs.c
index e85ab06819c..20d4180e9b9 100644
--- a/src/backend/utils/adt/selfuncs.c
+++ b/src/backend/utils/adt/selfuncs.c
@@ -15,7 +15,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/adt/selfuncs.c,v 1.262 2009/08/04 16:08:36 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/adt/selfuncs.c,v 1.263 2009/10/21 20:38:58 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -4580,7 +4580,6 @@ regex_fixed_prefix(Const *patt_const, bool case_insensitive,
 	char	   *patt;
 	char	   *rest;
 	Oid			typeid = patt_const->consttype;
-	bool		is_basic = regex_flavor_is_basic();
 	bool		is_multibyte = (pg_database_encoding_max_length() > 1);
 
 	/*
@@ -4598,14 +4597,12 @@ regex_fixed_prefix(Const *patt_const, bool case_insensitive,
 
 	/*
 	 * Check for ARE director prefix.  It's worth our trouble to recognize
-	 * this because similar_escape() uses it.
+	 * this because similar_escape() used to use it, and some other code
+	 * might still use it, to force ARE mode.
 	 */
 	pos = 0;
 	if (strncmp(patt, "***:", 4) == 0)
-	{
 		pos = 4;
-		is_basic = false;
-	}
 
 	/* Pattern must be anchored left */
 	if (patt[pos] != '^')
@@ -4641,17 +4638,11 @@ regex_fixed_prefix(Const *patt_const, bool case_insensitive,
 
 	/*
 	 * We special-case the syntax '^(...)$' because psql uses it.  But beware:
-	 * in BRE mode these parentheses are just ordinary characters.	Also,
 	 * sequences beginning "(?" are not what they seem, unless they're "(?:".
-	 * (We should recognize that, too, because of similar_escape().)
-	 *
-	 * Note: it's a bit bogus to be depending on the current regex_flavor
-	 * setting here, because the setting could change before the pattern is
-	 * used.  We minimize the risk by trusting the flavor as little as we can,
-	 * but perhaps it would be a good idea to get rid of the "basic" setting.
+	 * (We must recognize that because of similar_escape().)
 	 */
 	have_leading_paren = false;
-	if (patt[pos] == '(' && !is_basic &&
+	if (patt[pos] == '(' &&
 		(patt[pos + 1] != '?' || patt[pos + 2] == ':'))
 	{
 		have_leading_paren = true;
@@ -4691,12 +4682,10 @@ regex_fixed_prefix(Const *patt_const, bool case_insensitive,
 		/*
 		 * Check for quantifiers.  Except for +, this means the preceding
 		 * character is optional, so we must remove it from the prefix too!
-		 * Note: in BREs, \{ is a quantifier.
 		 */
 		if (patt[pos] == '*' ||
 			patt[pos] == '?' ||
-			patt[pos] == '{' ||
-			(patt[pos] == '\\' && patt[pos + 1] == '{'))
+			patt[pos] == '{')
 		{
 			match_pos = prev_match_pos;
 			pos = prev_pos;
@@ -4711,14 +4700,13 @@ regex_fixed_prefix(Const *patt_const, bool case_insensitive,
 		/*
 		 * Normally, backslash quotes the next character.  But in AREs,
 		 * backslash followed by alphanumeric is an escape, not a quoted
-		 * character.  Must treat it as having multiple possible matches. In
-		 * BREs, \( is a parenthesis, so don't trust that either. Note: since
-		 * only ASCII alphanumerics are escapes, we don't have to be paranoid
-		 * about multibyte here.
+		 * character.  Must treat it as having multiple possible matches.
+		 * Note: since only ASCII alphanumerics are escapes, we don't have to
+		 * be paranoid about multibyte here.
 		 */
 		if (patt[pos] == '\\')
 		{
-			if (isalnum((unsigned char) patt[pos + 1]) || patt[pos + 1] == '(')
+			if (isalnum((unsigned char) patt[pos + 1]))
 				break;
 			pos++;
 			if (patt[pos] == '\0')