prec.c

   1 /**********************************************************************
   2
   3   prec.c -
   4
   5   $Author$
   6   created at: Tue Jan 26 02:40:41 2000
   7
   8   Copyright (C) 1993-2007 Yukihiro Matsumoto
   9
  10 **********************************************************************/
  11
  12 #include "ruby/ruby.h"
  13
  14 VALUE rb_mPrecision;
  15
  16 static ID prc_pr, prc_if;
  17
  18
  19 /*
  20  *  call-seq:
  21  *   num.prec(klass)   => a_class
  22  *
  23  *  Converts _self_ into an instance of _klass_. By default,
  24  *  +prec+ invokes
  25  *
  26  *     klass.induced_from(num)
  27  *
  28  *  and returns its value. So, if <code>klass.induced_from</code>
  29  *  doesn't return an instance of _klass_, it will be necessary
  30  *  to reimplement +prec+.
  31  */
  32
  33 static VALUE
  34 prec_prec(VALUE x, VALUE klass)
  35 {
  36     return rb_funcall(klass, prc_if, 1, x);
  37 }
  38
  39 /*
  40  *  call-seq:
  41  *    num.prec_i  =>  Integer
  42  *
  43  *  Returns an +Integer+ converted from _num_. It is equivalent
  44  *  to <code>prec(Integer)</code>.
  45  */
  46
  47 static VALUE
  48 prec_prec_i(VALUE x)
  49 {
  50     VALUE klass = rb_cInteger;
  51
  52     return rb_funcall(x, prc_pr, 1, klass);
  53 }
  54
  55 /*
  56  *  call-seq:
  57  *    num.prec_f  =>  Float
  58  *
  59  *  Returns a +Float+ converted from _num_. It is equivalent
  60  *  to <code>prec(Float)</code>.
  61  */
  62
  63 static VALUE
  64 prec_prec_f(VALUE x)
  65 {
  66     VALUE klass = rb_cFloat;
  67
  68     return rb_funcall(x, prc_pr, 1, klass);
  69 }
  70
  71 /*
  72  * call-seq:
  73  *   Mod.induced_from(number)  =>  a_mod
  74  *
  75  * Creates an instance of mod from. This method is overridden
  76  * by concrete +Numeric+ classes, so that (for example)
  77  *
  78  *   Fixnum.induced_from(9.9)   #=>  9
  79  *
  80  * Note that a use of +prec+ in a redefinition may cause
  81  * an infinite loop.
  82  */
  83
  84 static VALUE
  85 prec_induced_from(VALUE module, VALUE x)
  86 {
  87     rb_raise(rb_eTypeError, "undefined conversion from %s into %s",
  88             rb_obj_classname(x), rb_class2name(module));
  89     return Qnil;                /* not reached */
  90 }
  91
  92 /*
  93  * call_seq:
  94  *   included
  95  *
  96  * When the +Precision+ module is mixed-in to a class, this +included+
  97  * method is used to add our default +induced_from+ implementation
  98  * to the host class.
  99  */
 100
 101 static VALUE
 102 prec_included(VALUE module, VALUE include)
 103 {
 104     switch (TYPE(include)) {
 105       case T_CLASS:
 106       case T_MODULE:
 107        break;
 108       default:
 109        Check_Type(include, T_CLASS);
 110        break;
 111     }
 112     rb_define_singleton_method(include, "induced_from", prec_induced_from, 1);
 113     return module;
 114 }
 115
 116 /*
 117  * Precision is a mixin for concrete numeric classes with
 118  * precision.  Here, `precision' means the fineness of approximation
 119  * of a real number, so, this module should not be included into
 120  * anything which is not a subset of Real (so it should not be
 121  * included in classes such as +Complex+ or +Matrix+).
 122 */
 123
 124 void
 125 Init_Precision(void)
 126 {
 127 #undef rb_intern
 128
 129     rb_mPrecision = rb_define_module("Precision");
 130     rb_define_singleton_method(rb_mPrecision, "included", prec_included, 1);
 131     rb_define_method(rb_mPrecision, "prec", prec_prec, 1);
 132     rb_define_method(rb_mPrecision, "prec_i", prec_prec_i, 0);
 133     rb_define_method(rb_mPrecision, "prec_f", prec_prec_f, 0);
 134
 135     prc_pr = rb_intern("prec");
 136     prc_if = rb_intern("induced_from");
 137 }