Function ExecInitExprWithParams

src/backend/executor/execExpr.c:171–200

* ExecInitExprWithParams: prepare a standalone expression tree for execution * * This is the same as ExecInitExpr, except that there is no parent PlanState, * and instead we may have a ParamListInfo describing PARAM_EXTERN Params. */

 * and instead we may have a ParamListInfo describing PARAM_EXTERN Params.
 */
ExprState *
ExecInitExprWithParams(Expr *node, ParamListInfo ext_params)
{
	ExprState  *state;
	ExprEvalStep scratch = {0};

	/* Special case: NULL expression produces a NULL ExprState pointer */
	if (node == NULL)
		return NULL;

	/* Initialize ExprState with empty step list */
	state = makeNode(ExprState);
	state->expr = node;
	state->parent = NULL;
	state->ext_params = ext_params;

	/* Insert EEOP_*_FETCHSOME steps as needed */
	ExecInitExprSlots(state, (Node *) node);

	/* Compile the expression proper */
	ExecInitExprRec(node, state, &state->resvalue, &state->resnull);

	/* Finally, append a DONE step */
	scratch.opcode = EEOP_DONE;
	ExprEvalPushStep(state, &scratch);

	ExecReadyExpr(state);

	return state;
}

/*
 * ExecInitQual: prepare a qual for execution by ExecQual