Function get_rule_expr

src/backend/utils/adt/ruleutils.c:8470–9857

---------- * get_rule_expr - Parse back an expression * * Note: showimplicit determines whether we display any implicit cast that * is present at the top of the expression tree. It is a passed argument, * not a field of the context struct, because we change the value as we * recurse down into the expression. In general we suppress implicit casts * when the result type is known with cert

 * ----------
 */
static void
get_rule_expr(Node *node, deparse_context *context,
			  bool showimplicit)
{
	StringInfo	buf = context->buf;

	if (node == NULL)
		return;

	/* Guard against excessively long or deeply-nested queries */
	CHECK_FOR_INTERRUPTS();
	check_stack_depth();

	/*
	 * Each level of get_rule_expr must emit an indivisible term
	 * (parenthesized if necessary) to ensure result is reparsed into the same
	 * expression tree.  The only exception is that when the input is a List,
	 * we emit the component items comma-separated with no surrounding
	 * decoration; this is convenient for most callers.
	 */
	switch (nodeTag(node))
	{
		case T_Var:
			(void) get_variable((Var *) node, 0, false, context);
			break;

		case T_Const:
			get_const_expr((Const *) node, context, 0);
			break;

		case T_Param:
			get_parameter((Param *) node, context);
			break;

		case T_Aggref:
			get_agg_expr((Aggref *) node, context, (Aggref *) node);
			break;
		case T_DQAExpr:
			get_dqa_expr((DQAExpr *) node, context);
			break;

		case T_GroupingFunc:
			{
				GroupingFunc *gexpr = (GroupingFunc *) node;

				appendStringInfoString(buf, "GROUPING(");
				get_rule_expr((Node *) gexpr->args, context, true);
				appendStringInfoChar(buf, ')');
			}
			break;
		case T_GroupId:
			appendStringInfo(buf, "GROUP_ID()");
			break;

		case T_GroupingSetId:
			appendStringInfo(buf, "GROUPINGSET_ID()");
			break;