compar.c

/**********************************************************************

 compar.c -

 $Author$
 created at: Thu Aug 26 14:39:48 JST 1993

 Copyright (C) 1993-2007 Yukihiro Matsumoto

**********************************************************************/

#include "ruby/ruby.h"
#include "id.h"
#include "internal.h"

VALUE rb_mComparable;

static VALUE
rb_cmp(VALUE x, VALUE y)
{
 return rb_funcallv(x, idCmp, 1, &y);
}

void
rb_cmperr(VALUE x, VALUE y)
{
 VALUE classname;

 if (SPECIAL_CONST_P(y) || BUILTIN_TYPE(y) == T_FLOAT) {
	classname = rb_inspect(y);
 }
 else {
	classname = rb_obj_class(y);
 }
 rb_raise(rb_eArgError, "comparison of %"PRIsVALUE" with %"PRIsVALUE" failed",
	 rb_obj_class(x), classname);
}

static VALUE
invcmp_recursive(VALUE x, VALUE y, int recursive)
{
 if (recursive) return Qnil;
 return rb_cmp(y, x);
}

VALUE
rb_invcmp(VALUE x, VALUE y)
{
 VALUE invcmp = rb_exec_recursive(invcmp_recursive, x, y);
 if (invcmp == Qundef || NIL_P(invcmp)) {
	return Qnil;
 }
 else {
	int result = -rb_cmpint(invcmp, x, y);
	return INT2FIX(result);
 }
}

static VALUE
cmp_eq_recursive(VALUE arg1, VALUE arg2, int recursive)
{
 if (recursive) return Qnil;
 return rb_cmp(arg1, arg2);
}

/*
 * call-seq:
 * obj == other -> true or false
 *
 * Compares two objects based on the receiver's <code><=></code>
 * method, returning true if it returns 0. Also returns true if
 * _obj_ and _other_ are the same object.
 */

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;
}

static int
cmpint(VALUE x, VALUE y)
{
 return rb_cmpint(rb_cmp(x, y), x, y);
}

/*
 * call-seq:
 * obj > other -> true or false
 *
 * Compares two objects based on the receiver's <code><=></code>
 * method, returning true if it returns a value greater than 0.
 */

static VALUE
cmp_gt(VALUE x, VALUE y)
{
 if (cmpint(x, y) > 0) return Qtrue;
 return Qfalse;
}

/*
 * call-seq:
 * obj >= other -> true or false
 *
 * Compares two objects based on the receiver's <code><=></code>
 * method, returning true if it returns a value greater than or equal to 0.
 */

static VALUE
cmp_ge(VALUE x, VALUE y)
{
 if (cmpint(x, y) >= 0) return Qtrue;
 return Qfalse;
}

/*
 * call-seq:
 * obj < other -> true or false
 *
 * Compares two objects based on the receiver's <code><=></code>
 * method, returning true if it returns a value less than 0.
 */

static VALUE
cmp_lt(VALUE x, VALUE y)
{
 if (cmpint(x, y) < 0) return Qtrue;
 return Qfalse;
}

/*
 * call-seq:
 * obj <= other -> true or false
 *
 * Compares two objects based on the receiver's <code><=></code>
 * method, returning true if it returns a value less than or equal to 0.
 */

static VALUE
cmp_le(VALUE x, VALUE y)
{
 if (cmpint(x, y) <= 0) return Qtrue;
 return Qfalse;
}

/*
 * call-seq:
 * obj.between?(min, max) -> true or false
 *
 * Returns <code>false</code> if _obj_ <code><=></code> _min_ is less
 * than zero or if _obj_ <code><=></code> _max_ is greater than zero,
 * <code>true</code> otherwise.
 *
 * 3.between?(1, 5) #=> true
 * 6.between?(1, 5) #=> false
 * 'cat'.between?('ant', 'dog') #=> true
 * 'gnu'.between?('ant', 'dog') #=> false
 *
 */

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;
}

/*
 * call-seq:
 * obj.clamp(min, max) -> obj
 * obj.clamp(range) -> obj
 *
 * In <code>(min, max)</code> form, returns _min_ if _obj_
 * <code><=></code> _min_ is less than zero, _max_ if _obj_
 * <code><=></code> _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 <code>(range)</code> form, returns _range.begin_ if _obj_
 * <code><=></code> _range.begin_ is less than zero, _range.end_
 * if _obj_ <code><=></code> _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
 */

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) && cmpint(min, max) > 0) goto arg_error;
 }
 }
 else if (cmpint(min, max) > 0) {
 arg_error:
	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;
}

/*
 * The Comparable mixin is used by classes whose objects may be
 * ordered. The class must define the <code><=></code> operator,
 * which compares the receiver against another object, returning
 * a value less than 0, 0, or 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 <code><=></code> operator should return +nil+.
 * Comparable uses <code><=></code> to implement the conventional
 * comparison operators (<code><</code>, <code><=</code>,
 * <code>==</code>, <code>>=</code>, and <code>></code>) and the
 * method <code>between?</code>.
 *
 * 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]
 *
 */

void
Init_Comparable(void)
{
#undef rb_intern
#define rb_intern(str) rb_intern_const(str)

 rb_mComparable = rb_define_module("Comparable");
 rb_define_method(rb_mComparable, "==", cmp_equal, 1);
 rb_define_method(rb_mComparable, ">", cmp_gt, 1);
 rb_define_method(rb_mComparable, ">=", cmp_ge, 1);
 rb_define_method(rb_mComparable, "<", cmp_lt, 1);
 rb_define_method(rb_mComparable, "<=", cmp_le, 1);
 rb_define_method(rb_mComparable, "between?", cmp_between, 2);
 rb_define_method(rb_mComparable, "clamp", cmp_clamp, -1);
}