Function InitFCInfoForCallStmt

pg_documentdb/src/commands/create_indexes.c:1239–1299

* InitFCInfoForCallStmt initializes given fcinfo by evaluating * expressions passed by given CallStmt and utility hook params. */

 * expressions passed by given CallStmt and utility hook params.
 */
void
InitFCInfoForCallStmt(FunctionCallInfo fcinfo, const CallStmt *callStmt,
					  ProcessUtilityContext context, const ParamListInfo params)
{
	/* verify that function exists */
	const FuncExpr *funcexpr = callStmt->funcexpr;
	HeapTuple procTuple = SearchSysCache1(PROCOID, ObjectIdGetDatum(funcexpr->funcid));
	if (!HeapTupleIsValid(procTuple))
	{
		ereport(ERROR, (errmsg("The function identified by OID %u could not be found",
							   funcexpr->funcid)));
	}

	ReleaseSysCache(procTuple);

	/*
	 * Seems that we don't need to expand function arguments in pg >= 14, see
	 * pg commit e56bce5d43789cce95d099554ae9593ada92b3b7.
	 *
	 * Also, copy expr list in case executor functions scribble on Expr nodes
	 * we pass.
	 */
	List *funcexprArgs = copyObject(funcexpr->args);

	EState *estate = CreateExecutorState();
	estate->es_param_list_info = params;
	ExprContext *econtext = CreateExprContext(estate);

	int argIdx = 0;
	ListCell *expandedArgCell;
	foreach(expandedArgCell, funcexprArgs)
	{
		ExprState *exprstate = ExecPrepareExpr(lfirst(expandedArgCell), estate);

		/*
		 * Since we will shutdown estate soon, we should not switch to
		 * its per tuple memory context to evaluate params, so we use
		 * ExecEvalExpr here instead of ExecEvalExprSwitchContext.
		 */
		bool isnull = false;
		Datum val = ExecEvalExpr(exprstate, econtext, &isnull);
		fcinfo->args[argIdx].value = val;
		fcinfo->args[argIdx].isnull = isnull;

		argIdx++;
	}

	/* initialize everything except args array, which we've already done */
	FmgrInfo *flinfo = palloc0(sizeof(FmgrInfo));
	fmgr_info(funcexpr->funcid, flinfo);
	fmgr_info_set_expr((Node *) funcexpr, flinfo);
	CallContext *callcontext = makeNode(CallContext);
	callcontext->atomic = (!(context == PROCESS_UTILITY_TOPLEVEL ||
							 context == PROCESS_UTILITY_QUERY_NONATOMIC) ||
						   IsTransactionBlock());
	InitFunctionCallInfoData(*fcinfo, flinfo, list_length(funcexprArgs),
							 funcexpr->inputcollid, (Node *) callcontext, NULL);