Assorted minor refactoring in EXPLAIN.

This is believed to not change the output at all, with one known exception:
"Subquery Scan foo" becomes "Subquery Scan on foo".  (We can fix that if
anyone complains, but it would be a wart, because the old code was clearly
inconsistent.)  The main intention is to remove duplicate coding and
provide a cleaner base for subsequent EXPLAIN patching.

Robert Haas

src/backend/lib/stringinfo.c

@@ -9,7 +9,7 @@
  * Portions Copyright (c) 1996-2009, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- *	  $PostgreSQL: pgsql/src/backend/lib/stringinfo.c,v 1.50 2009/01/01 17:23:42 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/lib/stringinfo.c,v 1.51 2009/07/24 21:08:42 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -186,6 +186,26 @@ appendStringInfoChar(StringInfo str, char ch)
 	str->data[str->len] = '\0';
 }
 
+/*
+ * appendStringInfoSpaces
+ *
+ * Append the specified number of spaces to a buffer.
+ */
+void
+appendStringInfoSpaces(StringInfo str, int count)
+{
+	if (count > 0)
+	{
+		/* Make more room if needed */
+		enlargeStringInfo(str, count);
+
+		/* OK, append the spaces */
+		while (--count >= 0)
+			str->data[str->len++] = ' ';
+		str->data[str->len] = '\0';
+	}
+}
+
 /*
  * appendBinaryStringInfo
  *

src/backend/utils/adt/ruleutils.c

@@ -9,7 +9,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/adt/ruleutils.c,v 1.303 2009/07/16 06:33:44 petere Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/adt/ruleutils.c,v 1.304 2009/07/24 21:08:42 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -187,7 +187,6 @@ static RangeTblEntry *find_rte_by_refname(const char *refname,
 					deparse_context *context);
 static const char *get_simple_binary_op_name(OpExpr *expr);
 static bool isSimpleNode(Node *node, Node *parentNode, int prettyFlags);
-static void appendStringInfoSpaces(StringInfo buf, int count);
 static void appendContextKeyword(deparse_context *context, const char *str,
 					 int indentBefore, int indentAfter, int indentPlus);
 static void get_rule_expr(Node *node, deparse_context *context,
@@ -4172,16 +4171,6 @@ isSimpleNode(Node *node, Node *parentNode, int prettyFlags)
 }
 
 
-/*
- * appendStringInfoSpaces - append spaces to buffer
- */
-static void
-appendStringInfoSpaces(StringInfo buf, int count)
-{
-	while (count-- > 0)
-		appendStringInfoChar(buf, ' ');
-}
-
 /*
  * appendContextKeyword - append a keyword to buffer
  *

src/include/lib/stringinfo.h

@@ -10,7 +10,7 @@
  * Portions Copyright (c) 1996-2009, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/lib/stringinfo.h,v 1.36 2009/01/01 17:23:59 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/lib/stringinfo.h,v 1.37 2009/07/24 21:08:42 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -131,6 +131,12 @@ extern void appendStringInfoChar(StringInfo str, char ch);
 	 appendStringInfoChar(str, ch) : \
 	 (void)((str)->data[(str)->len] = (ch), (str)->data[++(str)->len] = '\0'))
 
+/*------------------------
+ * appendStringInfoSpaces
+ * Append a given number of spaces to str.
+ */
+extern void appendStringInfoSpaces(StringInfo str, int count);
+
 /*------------------------
  * appendBinaryStringInfo
  * Append arbitrary binary data to a StringInfo, allocating more space