2 files changed, 84 insertions, 0 deletions
diff --git a/src/include/nodes/extensible.h b/src/include/nodes/extensible.h
new file mode 100644
index 00000000000..96ae7bc9291
--- /dev/null
+++ b/src/include/nodes/extensible.h
@@ -0,0 +1,72 @@
+/*-------------------------------------------------------------------------
+ *
+ * extensible.h
+ *    Definitions for extensible node type
+ *
+ *
+ * Portions Copyright (c) 1996-2016, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * src/include/nodes/extensible.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef EXTENSIBLE_H
+#define EXTENSIBLE_H
+
+#include "nodes/nodes.h"
+
+#define EXTNODENAME_MAX_LEN					64
+
+/*
+ * An extensible node is a new type of node defined by an extension.  The
+ * type is always T_ExtensibleNode, while the extnodename identifies the
+ * specific type of node.  extnodename can be looked up to find the
+ * ExtensibleNodeMethods for this node type.
+ */
+typedef struct ExtensibleNode
+{
+	NodeTag		type;
+	const char *extnodename;	/* identifier of ExtensibleNodeMethods */
+} ExtensibleNode;
+
+/*
+ * node_size is the size of an extensible node of this type in bytes.
+ *
+ * nodeCopy is a function which performs a deep copy from oldnode to newnode.
+ * It does not need to copy type or extnodename, which are copied by the
+ * core system.
+ *
+ * nodeEqual is a function which performs a deep equality comparison between
+ * a and b and returns true or false accordingly.  It does not need to compare
+ * type or extnodename, which are compared by the core system.
+ *
+ * nodeOut is a serialization function for the node type.  It should use the
+ * output conventions typical for outfuncs.c.  It does not need to output
+ * type or extnodename; the core system handles those.
+ *
+ * nodeRead is a deserialization function for the node type.  It does not need
+ * to read type or extnodename; the core system handles those.  It should fetch
+ * the next token using pg_strtok() from the current input stream, and then
+ * reconstruct the private fields according to the manner in readfuncs.c.
+ *
+ * All callbacks are mandatory.
+ */
+typedef struct ExtensibleNodeMethods
+{
+	const char *extnodename;
+	Size		node_size;
+	void	  (*nodeCopy)(struct ExtensibleNode *newnode,
+						  const struct ExtensibleNode *oldnode);
+	bool	  (*nodeEqual)(const struct ExtensibleNode *a,
+						   const struct ExtensibleNode *b);
+	void	  (*nodeOut)(struct StringInfoData *str,
+						 const struct ExtensibleNode *node);
+	void	  (*nodeRead)(struct ExtensibleNode *node);
+} ExtensibleNodeMethods;
+
+extern void RegisterExtensibleNodeMethods(const ExtensibleNodeMethods *method);
+extern const ExtensibleNodeMethods *GetExtensibleNodeMethods(const char *name,
+						 bool missing_ok);
+
+#endif	/* EXTENSIBLE_H */
diff --git a/src/include/nodes/nodes.h b/src/include/nodes/nodes.h
index cf09db4e5fe..c407fa2cd49 100644
--- a/src/include/nodes/nodes.h
+++ b/src/include/nodes/nodes.h
@@ -276,6 +276,11 @@ typedef enum NodeTag
 	T_OidList,
 
 	/*
+	 * TAGS FOR EXTENSIBLE NODES (extensible.h)
+	 */
+	T_ExtensibleNode,
+
+	/*
 	 * TAGS FOR STATEMENT NODES (mostly in parsenodes.h)
 	 */
 	T_Query = 700,
@@ -527,10 +532,17 @@ extern PGDLLIMPORT Node *newNodeMacroHolder;
  */
 extern char *nodeToString(const void *obj);
 
+struct Bitmapset;		/* not to include bitmapset.h here */
+struct StringInfoData;	/* not to include stringinfo.h here */
+extern void outToken(struct StringInfoData *str, const char *s);
+extern void outBitmapset(struct StringInfoData *str,
+						 const struct Bitmapset *bms);
+
 /*
  * nodes/{readfuncs.c,read.c}
  */
 extern void *stringToNode(char *str);
+extern struct Bitmapset *readBitmapset(void);
 
 /*
  * nodes/copyfuncs.c