Method: Date#<=>

Defined in:

ext/date/date_core.c

#<=>(other) ⇒ -1, ...

Compares self and other, returning:

• -1 if other is larger.

• 0 if the two are equal.

• 1 if other is smaller.

• nil if the two are incomparable.

Argument other may be:

• Another Date object:

  d = Date.new(2022, 7, 27) # => #<Date: 2022-07-27 ((2459788j,0s,0n),+0s,2299161j)>
  prev_date = d.prev_day    # => #<Date: 2022-07-26 ((2459787j,0s,0n),+0s,2299161j)>
  next_date = d.next_day    # => #<Date: 2022-07-28 ((2459789j,0s,0n),+0s,2299161j)>
  d <=> next_date           # => -1
  d <=> d                   # => 0
  d <=> prev_date           # => 1
  

• A DateTime object:

  d <=> DateTime.new(2022, 7, 26) # => 1
  d <=> DateTime.new(2022, 7, 27) # => 0
  d <=> DateTime.new(2022, 7, 28) # => -1
  

• A numeric (compares self.ajd to other):

  d <=> 2459788 # => -1
  d <=> 2459787 # => 1
  d <=> 2459786 # => 1
  d <=> d.ajd   # => 0
  

• Any other object:

  d <=> Object.new # => nil
  

Returns:

• (-1, 0, 1, nil)

# File 'ext/date/date_core.c', line 6825

static VALUE
d_lite_cmp(VALUE self, VALUE other)
{
    if (!k_date_p(other))
	return cmp_gen(self, other);

    {
	get_d2(self, other);

	if (!(simple_dat_p(adat) && simple_dat_p(bdat) &&
	      m_gregorian_p(adat) == m_gregorian_p(bdat)))
	    return cmp_dd(self, other);

	{
	    VALUE a_nth, b_nth;
	    int a_jd, b_jd;

	    m_canonicalize_jd(self, adat);
	    m_canonicalize_jd(other, bdat);
	    a_nth = m_nth(adat);
	    b_nth = m_nth(bdat);
	    if (f_eqeq_p(a_nth, b_nth)) {
		a_jd = m_jd(adat);
		b_jd = m_jd(bdat);
		if (a_jd == b_jd) {
		    return INT2FIX(0);
		}
		else if (a_jd < b_jd) {
		    return INT2FIX(-1);
		}
		else {
		    return INT2FIX(1);
		}
	    }
	    else if (f_lt_p(a_nth, b_nth)) {
		return INT2FIX(-1);
	    }
	    else {
		return INT2FIX(1);
	    }
	}
    }
}