问如何在Postgres中创建包含上限的新日期范围类型？

EN

CREATE TYPE daterange_;

CREATE FUNCTION date_minus(date1 date, date2 date) RETURNS float AS $$
    SELECT cast(date1 - date2 as float);
$$ LANGUAGE sql immutable;

CREATE FUNCTION dr_canonical(dr daterange_) RETURNS daterange_ AS $$
BEGIN
    IF NOT lower_inc(dr) THEN
        dr := daterange_(lower(dr) + 1, upper(dr), '[]');
    END IF;
    IF NOT upper_inc(dr) THEN
        dr := daterange_(lower(dr), upper(dr) - 1, '[]');
    END IF;
    RETURN dr;
END;
$$ LANGUAGE plpgsql;

CREATE TYPE daterange_ AS RANGE (
    SUBTYPE = date,
    SUBTYPE_DIFF = date_minus,
    CANONICAL = dr_canonical    
);

select daterange('2014/01/01', '2014/01/31', '[]');
        daterange        
-------------------------
 [2014-01-01,2014-02-01)

select '[2014/01/01, 2014/01/31]'::daterange;
        daterange        
-------------------------
 [2014-01-01,2014-02-01)

create function inclusive_upper_daterange(dtr daterange)
returns date as $$

    select upper(dtr) - 1;

$$ language sql immutable;

select inclusive_upper_daterange('[2014/01/01, 2014/01/31]'::daterange);
 inclusive_upper_daterange 
---------------------------
 2014-01-31

select
    WHEN upper_inc(mydaterange) THEN upper(mydaterange)
    ELSE date(upper(mydaterange)- INTERVAL '1 day')
 END