Function compare_values_of_enum

src/backend/utils/cache/typcache.c:2555–2623

* compare_values_of_enum * Compare two members of an enum type. * Return <0, 0, or >0 according as arg1 <, =, or > arg2. * * Note: currently, the enumData cache is refreshed only if we are asked * to compare an enum value that is not already in the cache. This is okay * because there is no support for re-ordering existing values, so comparisons * of previously cached values will return t

 * routine shouldn't even get called when that rule applies.
 */
int
compare_values_of_enum(TypeCacheEntry *tcache, Oid arg1, Oid arg2)
{
	TypeCacheEnumData *enumdata;
	EnumItem   *item1;
	EnumItem   *item2;

	/*
	 * Equal OIDs are certainly equal --- this case was probably handled by
	 * our caller, but we may as well check.
	 */
	if (arg1 == arg2)
		return 0;

	/* Load up the cache if first time through */
	if (tcache->enumData == NULL)
		load_enum_cache_data(tcache);
	enumdata = tcache->enumData;

	/*
	 * If both OIDs are known-sorted, we can just compare them directly.
	 */
	if (enum_known_sorted(enumdata, arg1) &&
		enum_known_sorted(enumdata, arg2))
	{
		if (arg1 < arg2)
			return -1;
		else
			return 1;
	}

	/*
	 * Slow path: we have to identify their actual sort-order positions.
	 */
	item1 = find_enumitem(enumdata, arg1);
	item2 = find_enumitem(enumdata, arg2);

	if (item1 == NULL || item2 == NULL)
	{
		/*
		 * We couldn't find one or both values.  That means the enum has
		 * changed under us, so re-initialize the cache and try again. We
		 * don't bother retrying the known-sorted case in this path.
		 */
		load_enum_cache_data(tcache);
		enumdata = tcache->enumData;

		item1 = find_enumitem(enumdata, arg1);
		item2 = find_enumitem(enumdata, arg2);

		/*
		 * If we still can't find the values, complain: we must have corrupt
		 * data.
		 */
		if (item1 == NULL)
			elog(ERROR, "enum value %u not found in cache for enum %s",
				 arg1, format_type_be(tcache->type_id));
		if (item2 == NULL)