summaryrefslogtreecommitdiff
path: root/prec.c
blob: c2e3032b7cc1d6e6bc141057a88d8ba0483c8c31 (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
/**********************************************************************

  prec.c -

  $Author$
  created at: Tue Jan 26 02:40:41 2000

  Copyright (C) 1993-2007 Yukihiro Matsumoto

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

#include "ruby/ruby.h"

VALUE rb_mPrecision;

static ID prc_pr, prc_if;


/*
 *  call-seq:
 *   num.prec(klass)   => a_class
 *
 *  Converts _self_ into an instance of _klass_. By default,
 *  +prec+ invokes 
 *
 *     klass.induced_from(num)
 *
 *  and returns its value. So, if <code>klass.induced_from</code>
 *  doesn't return an instance of _klass_, it will be necessary
 *  to reimplement +prec+.
 */

static VALUE
prec_prec(VALUE x, VALUE klass)
{
    return rb_funcall(klass, prc_if, 1, x);
}

/*
 *  call-seq:
 *    num.prec_i  =>  Integer
 *
 *  Returns an +Integer+ converted from _num_. It is equivalent 
 *  to <code>prec(Integer)</code>.
 */

static VALUE
prec_prec_i(VALUE x)
{
    VALUE klass = rb_cInteger;

    return rb_funcall(x, prc_pr, 1, klass);
}

/*
 *  call-seq:
 *    num.prec_f  =>  Float
 *
 *  Returns a +Float+ converted from _num_. It is equivalent 
 *  to <code>prec(Float)</code>.
 */

static VALUE
prec_prec_f(VALUE x)
{
    VALUE klass = rb_cFloat;

    return rb_funcall(x, prc_pr, 1, klass);
}

/*
 * call-seq:
 *   Mod.induced_from(number)  =>  a_mod
 * 
 * Creates an instance of mod from. This method is overridden
 * by concrete +Numeric+ classes, so that (for example)
 *
 *   Fixnum.induced_from(9.9)   #=>  9
 *
 * Note that a use of +prec+ in a redefinition may cause
 * an infinite loop.
 */

static VALUE
prec_induced_from(VALUE module, VALUE x)
{
    rb_raise(rb_eTypeError, "undefined conversion from %s into %s",
            rb_obj_classname(x), rb_class2name(module));
    return Qnil;		/* not reached */
}

/*
 * call_seq:
 *   included
 *
 * When the +Precision+ module is mixed-in to a class, this +included+
 * method is used to add our default +induced_from+ implementation
 * to the host class.
 */

static VALUE
prec_included(VALUE module, VALUE include)
{
    switch (TYPE(include)) {
      case T_CLASS:
      case T_MODULE:
       break;
      default:
       Check_Type(include, T_CLASS);
       break;
    }
    rb_define_singleton_method(include, "induced_from", prec_induced_from, 1);
    return module;
}

/*
 * Precision is a mixin for concrete numeric classes with
 * precision.  Here, `precision' means the fineness of approximation
 * of a real number, so, this module should not be included into
 * anything which is not a subset of Real (so it should not be
 * included in classes such as +Complex+ or +Matrix+).
*/

void
Init_Precision(void)
{
    rb_mPrecision = rb_define_module("Precision");
    rb_define_singleton_method(rb_mPrecision, "included", prec_included, 1);
    rb_define_method(rb_mPrecision, "prec", prec_prec, 1);
    rb_define_method(rb_mPrecision, "prec_i", prec_prec_i, 0);
    rb_define_method(rb_mPrecision, "prec_f", prec_prec_f, 0);

    prc_pr = rb_intern("prec");
    prc_if = rb_intern("induced_from");
}