/*
 * Lots of stuff copied from backend/utils/adt/rangetypes.c
 */

static RangeType *
range_union_internal(TypeCacheEntry *typcache, RangeType *r1, RangeType *r2,
           bool strict);

/*
 * Set union.  If strict is true, it is an error that the two input ranges
 * are not adjacent or overlapping.
 */
static RangeType *
range_union_internal(TypeCacheEntry *typcache, RangeType *r1, RangeType *r2,
           bool strict)
{
  RangeBound  lower1,
        lower2;
  RangeBound  upper1,
        upper2;
  bool    empty1,
        empty2;
  RangeBound *result_lower;
  RangeBound *result_upper;

  /* Different types should be prevented by ANYRANGE matching rules */
  if (RangeTypeGetOid(r1) != RangeTypeGetOid(r2))
    elog(ERROR, "range types do not match");

  range_deserialize(typcache, r1, &lower1, &upper1, &empty1);
  range_deserialize(typcache, r2, &lower2, &upper2, &empty2);

  /* if either is empty, the other is the correct answer */
  if (empty1)
    return r2;
  if (empty2)
    return r1;

  if (strict &&
    !DatumGetBool(range_overlaps_internal(typcache, r1, r2)) &&
    !DatumGetBool(range_adjacent_internal(typcache, r1, r2)))
    ereport(ERROR,
        (errcode(ERRCODE_DATA_EXCEPTION),
         errmsg("result of range union would not be contiguous")));

  if (range_cmp_bounds(typcache, &lower1, &lower2) < 0)
    result_lower = &lower1;
  else
    result_lower = &lower2;

  if (range_cmp_bounds(typcache, &upper1, &upper2) > 0)
    result_upper = &upper1;
  else
    result_upper = &upper2;

  return make_range(typcache, result_lower, result_upper, false);
}