Function transformArrayExpr

src/backend/parser/parse_expr.c:2010–2161

* transformArrayExpr * * If the caller specifies the target type, the resulting array will * be of exactly that type. Otherwise we try to infer a common type * for the elements using select_common_type(). */

 * for the elements using select_common_type().
 */
static Node *
transformArrayExpr(ParseState *pstate, A_ArrayExpr *a,
				   Oid array_type, Oid element_type, int32 typmod)
{
	ArrayExpr  *newa = makeNode(ArrayExpr);
	List	   *newelems = NIL;
	List	   *newcoercedelems = NIL;
	ListCell   *element;
	Oid			coerce_type;
	bool		coerce_hard;

	/*
	 * Transform the element expressions
	 *
	 * Assume that the array is one-dimensional unless we find an array-type
	 * element expression.
	 */
	newa->multidims = false;
	foreach(element, a->elements)
	{
		Node	   *e = (Node *) lfirst(element);
		Node	   *newe;

		/*
		 * If an element is itself an A_ArrayExpr, recurse directly so that we
		 * can pass down any target type we were given.
		 */
		if (IsA(e, A_ArrayExpr))
		{
			newe = transformArrayExpr(pstate,
									  (A_ArrayExpr *) e,
									  array_type,
									  element_type,
									  typmod);
			/* we certainly have an array here */
			Assert(array_type == InvalidOid || array_type == exprType(newe));
			newa->multidims = true;
		}
		else
		{
			newe = transformExprRecurse(pstate, e);

			/*
			 * Check for sub-array expressions, if we haven't already found
			 * one.
			 */
			if (!newa->multidims && type_is_array(exprType(newe)))
				newa->multidims = true;
		}

		newelems = lappend(newelems, newe);
	}

	/*
	 * Select a target type for the elements.
	 *
	 * If we haven't been given a target array type, we must try to deduce a
	 * common type based on the types of the individual elements present.