Scanner performance improvements

Use flex flags -CF.  Pass the to-be-scanned string around as StringInfo
type, to avoid querying the length repeatedly.  Clean up some code and
remove lex-compatibility cruft.  Escape backslash sequences inline.  Use
flex-provided yy_scan_buffer() function to set up input, rather than using
myinput().

Author: petere

src/backend/parser/Makefile

@@ -2,7 +2,7 @@
 #
 # Makefile for parser
 #
-# $Header: /cvsroot/pgsql/src/backend/parser/Makefile,v 1.36 2002/03/08 07:12:11 tgl Exp $
+# $Header: /cvsroot/pgsql/src/backend/parser/Makefile,v 1.37 2002/04/20 21:56:14 petere Exp $
 #
 #-------------------------------------------------------------------------
 
@@ -14,6 +14,8 @@ OBJS= analyze.o gram.o keywords.o parser.o parse_agg.o parse_clause.o \
       parse_expr.o parse_func.o parse_node.o parse_oper.o parse_relation.o \
       parse_type.o parse_coerce.o parse_target.o scan.o scansup.o
 
+FLEXFLAGS = -CF
+
 
 all: SUBSYS.o
 
@@ -42,7 +44,7 @@ endif
 
 $(srcdir)/scan.c: scan.l
 ifdef FLEX
-	$(FLEX) $(FLEXFLAGS) -Pbase_yy -o'$@' $<
+	$(FLEX) $(FLEXFLAGS) -o'$@' $<
 else
 	@$(missing) flex $< $@
 endif
@@ -59,13 +61,3 @@ clean:
 	rm -f SUBSYS.o $(OBJS)
 # And the garbage that might have been left behind by partial build:
 	@rm -f y.tab.c y.tab.h lex.yy.c
-
-
-# This is unusual:  We actually have to build some of the parts before
-# we know what the header file dependencies are.  
-dep depend: gram.c scan.c
-	$(CC) -MM $(CFLAGS) *.c >depend
-
-ifeq (depend,$(wildcard depend))
-include depend
-endif

src/backend/parser/parse_type.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/parser/parse_type.c,v 1.39 2002/03/30 01:02:41 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/parser/parse_type.c,v 1.40 2002/04/20 21:56:14 petere Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -473,17 +473,17 @@ typeidTypeRelid(Oid type_id)
 void
 parseTypeString(const char *str, Oid *type_id, int32 *typmod)
 {
-	char	   *buf;
+	StringInfoData buf;
 	List	   *raw_parsetree_list;
 	SelectStmt *stmt;
 	ResTarget  *restarget;
 	A_Const    *aconst;
 	TypeName   *typename;
 
-	buf = (char *) palloc(strlen(str) + 16);
-	sprintf(buf, "SELECT (NULL::%s)", str);
+	initStringInfo(&buf);
+	appendStringInfo(&buf, "SELECT (NULL::%s)", str);
 
-	raw_parsetree_list = parser(buf, NULL, 0);
+	raw_parsetree_list = parser(&buf, NULL, 0);
 
 	/*
 	 * Make sure we got back exactly what we expected and no more;
@@ -528,5 +528,5 @@ parseTypeString(const char *str, Oid *type_id, int32 *typmod)
 	*type_id = typenameTypeId(typename);
 	*typmod = typename->typmod;
 
-	pfree(buf);
+	pfree(buf.data);
 }

src/backend/parser/parser.c

@@ -14,7 +14,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/parser/parser.c,v 1.51 2001/11/05 17:46:26 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/parser/parser.c,v 1.52 2002/04/20 21:56:14 petere Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -28,12 +28,6 @@
 #include "parser/parse_expr.h"
 
 
-#if defined(FLEX_SCANNER)
-extern void DeleteBuffer(void);
-#endif   /* FLEX_SCANNER */
-
-char	   *parseString;		/* the char* which holds the string to be
-								 * parsed */
 List	   *parsetree;			/* result of parsing is left here */
 
 static int	lookahead_token;	/* one-token lookahead */
@@ -48,24 +42,20 @@ static bool have_lookahead;		/* lookahead_token set? */
  * Returns a list of raw (un-analyzed) parse trees.
  */
 List *
-parser(char *str, Oid *typev, int nargs)
+parser(StringInfo str, Oid *typev, int nargs)
 {
 	int			yyresult;
 
-	parseString = str;
 	parsetree = NIL;			/* in case parser forgets to set it */
 	have_lookahead = false;
 
-	scanner_init();
+	scanner_init(str);
 	parser_init(typev, nargs);
 	parse_expr_init();
 
 	yyresult = yyparse();
 
-#if defined(FLEX_SCANNER)
-	DeleteBuffer();
-#endif   /* FLEX_SCANNER */
-
+	scanner_finish();
 	clearerr(stdin);
 
 	if (yyresult)				/* error */