Function AggCheckCallContext

src/backend/executor/nodeAgg.c:4894–4919

* AggCheckCallContext - test if a SQL function is being called as an aggregate * * The transition and/or final functions of an aggregate may want to verify * that they are being called as aggregates, rather than as plain SQL * functions. They should use this function to do so. The return value * is nonzero if being called as an aggregate, or zero if not. (Specific * nonzero values are AGG

 * cache it in the transvalue itself (for internal-type transvalues).
 */
int
AggCheckCallContext(FunctionCallInfo fcinfo, MemoryContext *aggcontext)
{
	if (fcinfo->context && IsA(fcinfo->context, AggState))
	{
		if (aggcontext)
		{
			AggState   *aggstate = ((AggState *) fcinfo->context);
			ExprContext *cxt = aggstate->curaggcontext;

			*aggcontext = cxt->ecxt_per_tuple_memory;
		}
		return AGG_CONTEXT_AGGREGATE;
	}
	if (fcinfo->context && IsA(fcinfo->context, WindowAggState))
	{
		if (aggcontext)
			*aggcontext = ((WindowAggState *) fcinfo->context)->curaggcontext;
		return AGG_CONTEXT_WINDOW;
	}

	/* this is just to prevent "uninitialized variable" warnings */
	if (aggcontext)
		*aggcontext = NULL;
	return 0;
}

/*
 * AggGetAggref - allow an aggregate support function to get its Aggref