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/*-------------------------------------------------------------------------
*
* windowapi.h
* API for window functions to extract data from their window
*
* A window function does not receive its arguments in the normal way
* (and therefore the concept of strictness is irrelevant). Instead it
* receives a "WindowObject", which it can fetch with PG_WINDOW_OBJECT()
* (note V1 calling convention must be used). Correct call context can
* be tested with WindowObjectIsValid(). Although argument values are
* not passed, the call is correctly set up so that PG_NARGS() can be
* used and argument type information can be obtained with
* get_fn_expr_argtype(), get_fn_expr_arg_stable(), etc.
*
* Operations on the WindowObject allow the window function to find out
* the current row number, total number of rows in the partition, etc
* and to evaluate its argument expression(s) at various rows in the
* window partition. See the header comments for each WindowObject API
* function in nodeWindowAgg.c for details.
*
*
* Portions Copyright (c) 2000-2016, PostgreSQL Global Development Group
*
* src/include/windowapi.h
*
*-------------------------------------------------------------------------
*/
#ifndef WINDOWAPI_H
#define WINDOWAPI_H
/* values of "seektype" */
#define WINDOW_SEEK_CURRENT 0
#define WINDOW_SEEK_HEAD 1
#define WINDOW_SEEK_TAIL 2
/* this struct is private in nodeWindowAgg.c */
typedef struct WindowObjectData *WindowObject;
#define PG_WINDOW_OBJECT() ((WindowObject) fcinfo->context)
#define WindowObjectIsValid(winobj) \
((winobj) != NULL && IsA(winobj, WindowObjectData))
extern void *WinGetPartitionLocalMemory(WindowObject winobj, Size sz);
extern int64 WinGetCurrentPosition(WindowObject winobj);
extern int64 WinGetPartitionRowCount(WindowObject winobj);
extern void WinSetMarkPosition(WindowObject winobj, int64 markpos);
extern bool WinRowsArePeers(WindowObject winobj, int64 pos1, int64 pos2);
extern Datum WinGetFuncArgInPartition(WindowObject winobj, int argno,
int relpos, int seektype, bool set_mark,
bool *isnull, bool *isout);
extern Datum WinGetFuncArgInFrame(WindowObject winobj, int argno,
int relpos, int seektype, bool set_mark,
bool *isnull, bool *isout);
extern Datum WinGetFuncArgCurrent(WindowObject winobj, int argno,
bool *isnull);
#endif /* WINDOWAPI_H */
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