The Comparable mixin is used by classes whose objects may be ordered. The class must define the <=> operator, which compares the receiver against another object, returning a value less than 0, returning 0, or returning a value greater than 0, depending on whether the receiver is less than, equal to, or greater than the other object. If the other object is not comparable then the <=> operator should return nil. Comparable uses <=> to implement the conventional comparison operators (<, <=, ==, >=, and >) and the method between?.
class SizeMatters include Comparable attr :str def <=>(other) str.size <=> other.str.size end def initialize(str) @str = str end def inspect @str end end s1 = SizeMatters.new("Z") s2 = SizeMatters.new("YY") s3 = SizeMatters.new("XXX") s4 = SizeMatters.new("WWWW") s5 = SizeMatters.new("VVVVV") s1 < s2 #=> true s4.between?(s1, s3) #=> false s4.between?(s3, s5) #=> true [ s3, s2, s5, s4, s1 ].sort #=> [Z, YY, XXX, WWWW, VVVVV]
static VALUE
cmp_lt(VALUE x, VALUE y)
{
if (cmpint(x, y) < 0) return Qtrue;
return Qfalse;
}
Compares two objects based on the receiver’s <=> method, returning true if it returns a value less than 0.
static VALUE
cmp_le(VALUE x, VALUE y)
{
if (cmpint(x, y) <= 0) return Qtrue;
return Qfalse;
}
Compares two objects based on the receiver’s <=> method, returning true if it returns a value less than or equal to 0.
static VALUE
cmp_equal(VALUE x, VALUE y)
{
VALUE c;
if (x == y) return Qtrue;
c = rb_exec_recursive_paired_outer(cmp_eq_recursive, x, y, y);
if (NIL_P(c)) return Qfalse;
if (rb_cmpint(c, x, y) == 0) return Qtrue;
return Qfalse;
}
Compares two objects based on the receiver’s <=> method, returning true if it returns 0. Also returns true if obj and other are the same object.
static VALUE
cmp_gt(VALUE x, VALUE y)
{
if (cmpint(x, y) > 0) return Qtrue;
return Qfalse;
}
Compares two objects based on the receiver’s <=> method, returning true if it returns a value greater than 0.
static VALUE
cmp_ge(VALUE x, VALUE y)
{
if (cmpint(x, y) >= 0) return Qtrue;
return Qfalse;
}
Compares two objects based on the receiver’s <=> method, returning true if it returns a value greater than or equal to 0.
static VALUE
cmp_between(VALUE x, VALUE min, VALUE max)
{
if (cmpint(x, min) < 0) return Qfalse;
if (cmpint(x, max) > 0) return Qfalse;
return Qtrue;
}
Returns false if obj <=> min is less than zero or if obj <=> max is greater than zero, true otherwise.
3.between?(1, 5) #=> true 6.between?(1, 5) #=> false 'cat'.between?('ant', 'dog') #=> true 'gnu'.between?('ant', 'dog') #=> false
static VALUE
cmp_clamp(int argc, VALUE *argv, VALUE x)
{
VALUE min, max;
int c, excl = 0;
if (rb_scan_args(argc, argv, "11", &min, &max) == 1) {
VALUE range = min;
if (!rb_range_values(range, &min, &max, &excl)) {
rb_raise(rb_eTypeError, "wrong argument type %s (expected Range)",
rb_builtin_class_name(range));
}
if (!NIL_P(max)) {
if (excl) rb_raise(rb_eArgError, "cannot clamp with an exclusive range");
}
}
if (!NIL_P(min) && !NIL_P(max) && cmpint(min, max) > 0) {
rb_raise(rb_eArgError, "min argument must be smaller than max argument");
}
if (!NIL_P(min)) {
c = cmpint(x, min);
if (c == 0) return x;
if (c < 0) return min;
}
if (!NIL_P(max)) {
c = cmpint(x, max);
if (c > 0) return max;
}
return x;
}
In (min, max) form, returns min if obj <=> min is less than zero, max if obj <=> max is greater than zero, and obj otherwise.
12.clamp(0, 100) #=> 12 523.clamp(0, 100) #=> 100 -3.123.clamp(0, 100) #=> 0 'd'.clamp('a', 'f') #=> 'd' 'z'.clamp('a', 'f') #=> 'f'
In (range) form, returns range.begin if obj <=> range.begin is less than zero, range.end if obj <=> range.end is greater than zero, and obj otherwise.
12.clamp(0..100) #=> 12 523.clamp(0..100) #=> 100 -3.123.clamp(0..100) #=> 0 'd'.clamp('a'..'f') #=> 'd' 'z'.clamp('a'..'f') #=> 'f'
If range.begin is nil, it is considered smaller than obj, and if range.end is nil, it is considered greater than obj.
-20.clamp(0..) #=> 0 523.clamp(..100) #=> 100
When range.end is excluded and not nil, an exception is raised.
100.clamp(0...100) # ArgumentError