summaryrefslogtreecommitdiff
path: root/compar.c
blob: b028a256ece9dc6f4385ab78d606c2c2135499d7 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
/**********************************************************************

  compar.c -

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

  Copyright (C) 1993-2007 Yukihiro Matsumoto

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

#include "ruby/ruby.h"

VALUE rb_mComparable;

static ID cmp;

void
rb_cmperr(VALUE x, VALUE y)
{
    const char *classname;

    if (SPECIAL_CONST_P(y)) {
	y = rb_inspect(y);
	classname = StringValuePtr(y);
    }
    else {
	classname = rb_obj_classname(y);
    }
    rb_raise(rb_eArgError, "comparison of %s with %s failed",
	     rb_obj_classname(x), classname);
}

static VALUE
cmp_eq(VALUE *a)
{
    VALUE c = rb_funcall(a[0], cmp, 1, a[1]);

    if (NIL_P(c)) return Qfalse;
    if (rb_cmpint(c, a[0], a[1]) == 0) return Qtrue;
    return Qfalse;
}

static VALUE
cmp_failed(void)
{
    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 0. Also returns true if
 *  _obj_ and _other_ are the same object.
 */

static VALUE
cmp_equal(VALUE x, VALUE y)
{
    VALUE a[2];

    if (x == y) return Qtrue;

    a[0] = x; a[1] = y;
    return rb_rescue(cmp_eq, (VALUE)a, cmp_failed, 0);
}

/*
 *  call-seq:
 *     obj > other    => true or false
 *  
 *  Compares two objects based on the receiver's <code><=></code>
 *  method, returning true if it returns 1.
 */

static VALUE
cmp_gt(VALUE x, VALUE y)
{
    VALUE c = rb_funcall(x, cmp, 1, y);

    if (rb_cmpint(c, 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 0 or 1.
 */

static VALUE
cmp_ge(VALUE x, VALUE y)
{
    VALUE c = rb_funcall(x, cmp, 1, y);

    if (rb_cmpint(c, 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 -1.
 */

static VALUE
cmp_lt(VALUE x, VALUE y)
{
    VALUE c = rb_funcall(x, cmp, 1, y);

    if (rb_cmpint(c, 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 -1 or 0.
 */

static VALUE
cmp_le(VALUE x, VALUE y)
{
    VALUE c = rb_funcall(x, cmp, 1, y);

    if (rb_cmpint(c, x, y) <= 0) return Qtrue;
    return Qfalse;
}

/*
 *  call-seq:
 *     obj.between?(min, max)    => true or false
 *  
 *  Returns <code>false</code> if <i>obj</i> <code><=></code>
 *  <i>min</i> is less than zero or if <i>anObject</i> <code><=></code>
 *  <i>max</i> 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 (RTEST(cmp_lt(x, min))) return Qfalse;
    if (RTEST(cmp_gt(x, max))) return Qfalse;
    return Qtrue;
}

/*
 *  The <code>Comparable</code> 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 -1, 0,
 *  or +1 depending on whether the receiver is less than, equal to, or
 *  greater than the other object. <code>Comparable</code> 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 <=>(anOther)
 *         str.size <=> anOther.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

    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);

    cmp = rb_intern("<=>");
}