compar.c

   1 /**********************************************************************
   2
   3   compar.c -
   4
   5   $Author$
   6   created at: Thu Aug 26 14:39:48 JST 1993
   7
   8   Copyright (C) 1993-2007 Yukihiro Matsumoto
   9
  10 **********************************************************************/
  11
  12 #include "ruby/ruby.h"
  13
  14 VALUE rb_mComparable;
  15
  16 static ID cmp;
  17
  18 void
  19 rb_cmperr(VALUE x, VALUE y)
  20 {
  21     const char *classname;
  22
  23     if (SPECIAL_CONST_P(y)) {
  24         y = rb_inspect(y);
  25         classname = StringValuePtr(y);
  26     }
  27     else {
  28         classname = rb_obj_classname(y);
  29     }
  30     rb_raise(rb_eArgError, "comparison of %s with %s failed",
  31              rb_obj_classname(x), classname);
  32 }
  33
  34 static VALUE
  35 cmp_eq(VALUE *a)
  36 {
  37     VALUE c = rb_funcall(a[0], cmp, 1, a[1]);
  38
  39     if (NIL_P(c)) return Qfalse;
  40     if (rb_cmpint(c, a[0], a[1]) == 0) return Qtrue;
  41     return Qfalse;
  42 }
  43
  44 static VALUE
  45 cmp_failed(void)
  46 {
  47     return Qfalse;
  48 }
  49
  50 /*
  51  *  call-seq:
  52  *     obj == other    => true or false
  53  *
  54  *  Compares two objects based on the receiver's <code><=></code>
  55  *  method, returning true if it returns 0. Also returns true if
  56  *  _obj_ and _other_ are the same object.
  57  */
  58
  59 static VALUE
  60 cmp_equal(VALUE x, VALUE y)
  61 {
  62     VALUE a[2];
  63
  64     if (x == y) return Qtrue;
  65
  66     a[0] = x; a[1] = y;
  67     return rb_rescue(cmp_eq, (VALUE)a, cmp_failed, 0);
  68 }
  69
  70 /*
  71  *  call-seq:
  72  *     obj > other    => true or false
  73  *
  74  *  Compares two objects based on the receiver's <code><=></code>
  75  *  method, returning true if it returns 1.
  76  */
  77
  78 static VALUE
  79 cmp_gt(VALUE x, VALUE y)
  80 {
  81     VALUE c = rb_funcall(x, cmp, 1, y);
  82
  83     if (rb_cmpint(c, x, y) > 0) return Qtrue;
  84     return Qfalse;
  85 }
  86
  87 /*
  88  *  call-seq:
  89  *     obj >= other    => true or false
  90  *
  91  *  Compares two objects based on the receiver's <code><=></code>
  92  *  method, returning true if it returns 0 or 1.
  93  */
  94
  95 static VALUE
  96 cmp_ge(VALUE x, VALUE y)
  97 {
  98     VALUE c = rb_funcall(x, cmp, 1, y);
  99
 100     if (rb_cmpint(c, x, y) >= 0) return Qtrue;
 101     return Qfalse;
 102 }
 103
 104 /*
 105  *  call-seq:
 106  *     obj < other    => true or false
 107  *
 108  *  Compares two objects based on the receiver's <code><=></code>
 109  *  method, returning true if it returns -1.
 110  */
 111
 112 static VALUE
 113 cmp_lt(VALUE x, VALUE y)
 114 {
 115     VALUE c = rb_funcall(x, cmp, 1, y);
 116
 117     if (rb_cmpint(c, x, y) < 0) return Qtrue;
 118     return Qfalse;
 119 }
 120
 121 /*
 122  *  call-seq:
 123  *     obj <= other    => true or false
 124  *
 125  *  Compares two objects based on the receiver's <code><=></code>
 126  *  method, returning true if it returns -1 or 0.
 127  */
 128
 129 static VALUE
 130 cmp_le(VALUE x, VALUE y)
 131 {
 132     VALUE c = rb_funcall(x, cmp, 1, y);
 133
 134     if (rb_cmpint(c, x, y) <= 0) return Qtrue;
 135     return Qfalse;
 136 }
 137
 138 /*
 139  *  call-seq:
 140  *     obj.between?(min, max)    => true or false
 141  *
 142  *  Returns <code>false</code> if <i>obj</i> <code><=></code>
 143  *  <i>min</i> is less than zero or if <i>anObject</i> <code><=></code>
 144  *  <i>max</i> is greater than zero, <code>true</code> otherwise.
 145  *
 146  *     3.between?(1, 5)               #=> true
 147  *     6.between?(1, 5)               #=> false
 148  *     'cat'.between?('ant', 'dog')   #=> true
 149  *     'gnu'.between?('ant', 'dog')   #=> false
 150  *
 151  */
 152
 153 static VALUE
 154 cmp_between(VALUE x, VALUE min, VALUE max)
 155 {
 156     if (RTEST(cmp_lt(x, min))) return Qfalse;
 157     if (RTEST(cmp_gt(x, max))) return Qfalse;
 158     return Qtrue;
 159 }
 160
 161 /*
 162  *  The <code>Comparable</code> mixin is used by classes whose objects
 163  *  may be ordered. The class must define the <code><=></code> operator,
 164  *  which compares the receiver against another object, returning -1, 0,
 165  *  or +1 depending on whether the receiver is less than, equal to, or
 166  *  greater than the other object. <code>Comparable</code> uses
 167  *  <code><=></code> to implement the conventional comparison operators
 168  *  (<code><</code>, <code><=</code>, <code>==</code>, <code>>=</code>,
 169  *  and <code>></code>) and the method <code>between?</code>.
 170  *
 171  *     class SizeMatters
 172  *       include Comparable
 173  *       attr :str
 174  *       def <=>(anOther)
 175  *         str.size <=> anOther.str.size
 176  *       end
 177  *       def initialize(str)
 178  *         @str = str
 179  *       end
 180  *       def inspect
 181  *         @str
 182  *       end
 183  *     end
 184  *
 185  *     s1 = SizeMatters.new("Z")
 186  *     s2 = SizeMatters.new("YY")
 187  *     s3 = SizeMatters.new("XXX")
 188  *     s4 = SizeMatters.new("WWWW")
 189  *     s5 = SizeMatters.new("VVVVV")
 190  *
 191  *     s1 < s2                       #=> true
 192  *     s4.between?(s1, s3)           #=> false
 193  *     s4.between?(s3, s5)           #=> true
 194  *     [ s3, s2, s5, s4, s1 ].sort   #=> [Z, YY, XXX, WWWW, VVVVV]
 195  *
 196  */
 197
 198 void
 199 Init_Comparable(void)
 200 {
 201     rb_mComparable = rb_define_module("Comparable");
 202     rb_define_method(rb_mComparable, "==", cmp_equal, 1);
 203     rb_define_method(rb_mComparable, ">", cmp_gt, 1);
 204     rb_define_method(rb_mComparable, ">=", cmp_ge, 1);
 205     rb_define_method(rb_mComparable, "<", cmp_lt, 1);
 206     rb_define_method(rb_mComparable, "<=", cmp_le, 1);
 207     rb_define_method(rb_mComparable, "between?", cmp_between, 2);
 208
 209     cmp = rb_intern("<=>");
 210 }