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/*-------------------------------------------------------------------------
*
* extensible.h
* Definitions for extensible nodes and custom scans
*
*
* 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
/* maximum length of an extensible node identifier */
#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);
/*
* Flags for custom paths, indicating what capabilities the resulting scan
* will have.
*/
#define CUSTOMPATH_SUPPORT_BACKWARD_SCAN 0x0001
#define CUSTOMPATH_SUPPORT_MARK_RESTORE 0x0002
#endif /* EXTENSIBLE_H */
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