Function transformContainerType

src/backend/parser/parse_node.c:193–216

* transformContainerType() * Identify the actual container type for a subscripting operation. * * containerType/containerTypmod are modified if necessary to identify * the actual container type and typmod. This mainly involves smashing * any domain to its base type, but there are some special considerations. * Note that caller still needs to check if the result type is a container. */

 * Note that caller still needs to check if the result type is a container.
 */
void
transformContainerType(Oid *containerType, int32 *containerTypmod)
{
	/*
	 * If the input is a domain, smash to base type, and extract the actual
	 * typmod to be applied to the base type. Subscripting a domain is an
	 * operation that necessarily works on the base container type, not the
	 * domain itself. (Note that we provide no method whereby the creator of a
	 * domain over a container type could hide its ability to be subscripted.)
	 */
	*containerType = getBaseTypeAndTypmod(*containerType, containerTypmod);

	/*
	 * We treat int2vector and oidvector as though they were domains over
	 * int2[] and oid[].  This is needed because array slicing could create an
	 * array that doesn't satisfy the dimensionality constraints of the
	 * xxxvector type; so we want the result of a slice operation to be
	 * considered to be of the more general type.
	 */
	if (*containerType == INT2VECTOROID)
		*containerType = INT2ARRAYOID;
	else if (*containerType == OIDVECTOROID)
		*containerType = OIDARRAYOID;
}

/*
 * transformContainerSubscripts()