Add debugging aid "bmsToString(Bitmapset *bms)".

This function has no direct callers at present, but it's convenient for
manual use in a debugger, rather than having to inspect memory and do
bit-counting in your head.

In passing, get rid of useless outBitmapset() wrapper around
_outBitmapset(); let's just export the function that does the work.
Likewise for outToken().

Ashutosh Bapat, tweaked a bit by me

Discussion: <CAFjFpRdiht8e1HTVirbubr4YzaON5iZTzFJjq909y4sU8M_6eA@mail.gmail.com>

src/backend/nodes/outfuncs.c

@@ -81,7 +81,7 @@
 /* Write a character-string (possibly NULL) field */
 #define WRITE_STRING_FIELD(fldname) \
 	(appendStringInfo(str, " :" CppAsString(fldname) " "), \
-	 _outToken(str, node->fldname))
+	 outToken(str, node->fldname))
 
 /* Write a parse location field (actually same as INT case) */
 #define WRITE_LOCATION_FIELD(fldname) \
@@ -95,21 +95,21 @@
 /* Write a bitmapset field */
 #define WRITE_BITMAPSET_FIELD(fldname) \
 	(appendStringInfo(str, " :" CppAsString(fldname) " "), \
-	 _outBitmapset(str, node->fldname))
+	 outBitmapset(str, node->fldname))
 
 
 #define booltostr(x)  ((x) ? "true" : "false")
 
 
 /*
- * _outToken
+ * outToken
  *	  Convert an ordinary string (eg, an identifier) into a form that
  *	  will be decoded back to a plain token by read.c's functions.
  *
  *	  If a null or empty string is given, it is encoded as "<>".
  */
-static void
+void
-_outToken(StringInfo str, const char *s)
+outToken(StringInfo str, const char *s)
 {
 	if (s == NULL || *s == '\0')
 	{
@@ -140,13 +140,6 @@ _outToken(StringInfo str, const char *s)
 	}
 }
 
-/* for use by extensions which define extensible nodes */
-void
-outToken(StringInfo str, const char *s)
-{
-	_outToken(str, s);
-}
-
 static void
 _outList(StringInfo str, const List *node)
 {
@@ -185,13 +178,13 @@ _outList(StringInfo str, const List *node)
 }
 
 /*
- * _outBitmapset -
+ * outBitmapset -
  *	   converts a bitmap set of integers
  *
  * Note: the output format is "(b int int ...)", similar to an integer List.
  */
-static void
+void
-_outBitmapset(StringInfo str, const Bitmapset *bms)
+outBitmapset(StringInfo str, const Bitmapset *bms)
 {
 	int			x;
 
@@ -203,13 +196,6 @@ _outBitmapset(StringInfo str, const Bitmapset *bms)
 	appendStringInfoChar(str, ')');
 }
 
-/* for use by extensions which define extensible nodes */
-void
-outBitmapset(StringInfo str, const Bitmapset *bms)
-{
-	_outBitmapset(str, bms);
-}
-
 /*
  * Print the value of a Datum given its type.
  */
@@ -632,7 +618,7 @@ _outCustomScan(StringInfo str, const CustomScan *node)
 	WRITE_BITMAPSET_FIELD(custom_relids);
 	/* CustomName is a key to lookup CustomScanMethods */
 	appendStringInfoString(str, " :methods ");
-	_outToken(str, node->methods->CustomName);
+	outToken(str, node->methods->CustomName);
 }
 
 static void
@@ -1196,7 +1182,7 @@ _outBoolExpr(StringInfo str, const BoolExpr *node)
 			break;
 	}
 	appendStringInfoString(str, " :boolop ");
-	_outToken(str, opstr);
+	outToken(str, opstr);
 
 	WRITE_NODE_FIELD(args);
 	WRITE_LOCATION_FIELD(location);
@@ -1609,14 +1595,14 @@ _outPathInfo(StringInfo str, const Path *node)
 {
 	WRITE_ENUM_FIELD(pathtype, NodeTag);
 	appendStringInfoString(str, " :parent_relids ");
-	_outBitmapset(str, node->parent->relids);
+	outBitmapset(str, node->parent->relids);
 	if (node->pathtarget != node->parent->reltarget)
 		WRITE_NODE_FIELD(pathtarget);
 	appendStringInfoString(str, " :required_outer ");
 	if (node->param_info)
-		_outBitmapset(str, node->param_info->ppi_req_outer);
+		outBitmapset(str, node->param_info->ppi_req_outer);
 	else
-		_outBitmapset(str, NULL);
+		outBitmapset(str, NULL);
 	WRITE_BOOL_FIELD(parallel_aware);
 	WRITE_BOOL_FIELD(parallel_safe);
 	WRITE_INT_FIELD(parallel_workers);
@@ -1740,7 +1726,7 @@ _outCustomPath(StringInfo str, const CustomPath *node)
 	WRITE_NODE_FIELD(custom_paths);
 	WRITE_NODE_FIELD(custom_private);
 	appendStringInfoString(str, " :methods ");
-	_outToken(str, node->methods->CustomName);
+	outToken(str, node->methods->CustomName);
 }
 
 static void
@@ -2994,12 +2980,12 @@ _outValue(StringInfo str, const Value *value)
 		case T_String:
 
 			/*
-			 * We use _outToken to provide escaping of the string's content,
+			 * We use outToken to provide escaping of the string's content,
 			 * but we don't want it to do anything with an empty string.
 			 */
 			appendStringInfoChar(str, '"');
 			if (value->val.str[0] != '\0')
-				_outToken(str, value->val.str);
+				outToken(str, value->val.str);
 			appendStringInfoChar(str, '"');
 			break;
 		case T_BitString:
@@ -3895,3 +3881,18 @@ nodeToString(const void *obj)
 	outNode(&str, obj);
 	return str.data;
 }
+
+/*
+ * bmsToString -
+ *	   returns the ascii representation of the Bitmapset as a palloc'd string
+ */
+char *
+bmsToString(const Bitmapset *bms)
+{
+	StringInfoData str;
+
+	/* see stringinfo.h for an explanation of this maneuver */
+	initStringInfo(&str);
+	outBitmapset(&str, bms);
+	return str.data;
+}

src/include/nodes/nodes.h

@@ -551,16 +551,17 @@ extern PGDLLIMPORT Node *newNodeMacroHolder;
 /*
  * nodes/{outfuncs.c,print.c}
  */
-extern char *nodeToString(const void *obj);
-
 struct Bitmapset;				/* not to include bitmapset.h here */
 struct StringInfoData;			/* not to include stringinfo.h here */
+
 extern void outNode(struct StringInfoData *str, const void *obj);
 extern void outToken(struct StringInfoData *str, const char *s);
 extern void outBitmapset(struct StringInfoData *str,
 			 const struct Bitmapset *bms);
 extern void outDatum(struct StringInfoData *str, uintptr_t value,
 		 int typlen, bool typbyval);
+extern char *nodeToString(const void *obj);
+extern char *bmsToString(const struct Bitmapset *bms);
 
 /*
  * nodes/{readfuncs.c,read.c}