Tweak the core scanner so that it can be used by plpgsql too.

Changes:

Pass in the keyword lookup array instead of having it be hardwired.
(This incidentally allows elimination of some duplicate coding in ecpg.)

Re-order the token declarations in gram.y so that non-keyword tokens have
numbers that won't change when keywords are added or removed.

Add ".." and ":=" to the set of tokens recognized by scan.l.  (Since these
combinations are nowhere legal in core SQL, this does not change anything
except the precise wording of the error you get when you write this.)

src/interfaces/ecpg/preproc/c_keywords.c

@@ -1,10 +1,10 @@
 /*-------------------------------------------------------------------------
  *
- * keywords.c
+ * c_keywords.c
  *	  lexical token lookup for reserved words in postgres embedded SQL
  *
- * $PostgreSQL: pgsql/src/interfaces/ecpg/preproc/c_keywords.c,v 1.23 2009/06/11 14:49:13 momjian Exp $
- * §
+ * $PostgreSQL: pgsql/src/interfaces/ecpg/preproc/c_keywords.c,v 1.24 2009/07/14 20:24:10 tgl Exp $
+ *
  *-------------------------------------------------------------------------
  */
 #include "postgres_fe.h"
@@ -55,8 +55,31 @@ static const ScanKeyword ScanCKeywords[] = {
 	{"year", YEAR_P, 0},
 };
 
+
+/*
+ * Do a binary search using plain strcmp() comparison.  This is much like
+ * ScanKeywordLookup(), except we want case-sensitive matching.
+ */
 const ScanKeyword *
 ScanCKeywordLookup(const char *text)
 {
-	return DoLookup(text, &ScanCKeywords[0], endof(ScanCKeywords) - 1);
+	const ScanKeyword *low = &ScanCKeywords[0];
+	const ScanKeyword *high = &ScanCKeywords[lengthof(ScanCKeywords) - 1];
+
+	while (low <= high)
+	{
+		const ScanKeyword *middle;
+		int			difference;
+
+		middle = low + (high - low) / 2;
+		difference = strcmp(middle->name, text);
+		if (difference == 0)
+			return middle;
+		else if (difference < 0)
+			low = middle + 1;
+		else
+			high = middle - 1;
+	}
+
+	return NULL;
 }