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/*--------------------------------------------------------------------
* Symbols referenced in this file:
* - GetExtensibleNodeMethods
* - GetExtensibleNodeEntry
* - extensible_node_methods
*--------------------------------------------------------------------
*/
/*-------------------------------------------------------------------------
*
* extensible.c
* Support for extensible node types
*
* Loadable modules can define what are in effect new types of nodes using
* the routines in this file. All such nodes are flagged T_ExtensibleNode,
* with the extnodename field distinguishing the specific type. Use
* RegisterExtensibleNodeMethods to register a new type of extensible node,
* and GetExtensibleNodeMethods to get information about a previously
* registered type of extensible node.
*
* Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* src/backend/nodes/extensible.c
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "nodes/extensible.h"
#include "utils/hsearch.h"
static __thread HTAB *extensible_node_methods = NULL;
typedef struct
{
char extnodename[EXTNODENAME_MAX_LEN];
const void *extnodemethods;
} ExtensibleNodeEntry;
/*
* An internal function to register a new callback structure
*/
/*
* Register a new type of extensible node.
*/
/*
* Register a new type of custom scan node
*/
/*
* An internal routine to get an ExtensibleNodeEntry by the given identifier
*/
static const void *
GetExtensibleNodeEntry(HTAB *htable, const char *extnodename, bool missing_ok)
{
ExtensibleNodeEntry *entry = NULL;
if (htable != NULL)
entry = (ExtensibleNodeEntry *) hash_search(htable,
extnodename,
HASH_FIND, NULL);
if (!entry)
{
if (missing_ok)
return NULL;
ereport(ERROR,
(errcode(ERRCODE_UNDEFINED_OBJECT),
errmsg("ExtensibleNodeMethods \"%s\" was not registered",
extnodename)));
}
return entry->extnodemethods;
}
/*
* Get the methods for a given type of extensible node.
*/
const ExtensibleNodeMethods *
GetExtensibleNodeMethods(const char *extnodename, bool missing_ok)
{
return (const ExtensibleNodeMethods *)
GetExtensibleNodeEntry(extensible_node_methods,
extnodename,
missing_ok);
}
/*
* Get the methods for a given name of CustomScanMethods
*/
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