compar.c (130c9ec44bd35c7319cdc99c301419188510e3a9)

/**********************************************************************
 
  compar.c -
 
  $Author$
  created at: Thu Aug 26 14:39:48 JST 1993
 
  Copyright (C) 1993-2007 Yukihiro Matsumoto
 
**********************************************************************/
 
#include "id.h"
#include "internal.h"
#include "internal/compar.h"
#include "internal/error.h"
#include "internal/vm.h"
#include "ruby/ruby.h"
 
VALUE rb_mComparable;
 
static VALUE
rb_cmp(VALUE x, VALUE y)
{
    return rb_funcallv(x, idCmp, 1, &y);
}
 
static VALUE
cmperr_subject(VALUE y)
{
    VALUE classname;
 
    if (SPECIAL_CONST_P(y) || BUILTIN_TYPE(y) == T_FLOAT) {
        classname = rb_inspect(y);
    }
    else {
        classname = rb_obj_class(y);
    }
    return classname;
}
 
void
rb_cmperr(VALUE x, VALUE y)
{
    VALUE classname = cmperr_subject(y);
    rb_raise(rb_eArgError, "comparison of %"PRIsVALUE" with %"PRIsVALUE" failed",
             rb_obj_class(x), classname);
}
 
void
rb_cmperr_reason(VALUE x, VALUE y, const char *reason)
{
    VALUE classname = cmperr_subject(y);
    rb_raise(rb_eArgError, "comparison of %"PRIsVALUE" with %"PRIsVALUE" failed: %s",
             rb_obj_class(x), classname, reason);
}
 
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 (NIL_OR_UNDEF_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;
    return RBOOL(rb_cmpint(c, x, y) == 0);
}
 
static int
cmpint(VALUE x, VALUE y)
{
    return rb_cmpint(rb_cmp(x, y), x, y);
}
 
/*
 *  call-seq:
 *    self > other -> true or false
 *
 *  Returns whether +self+ is "greater than" +other+;
 *  equivalent to <tt>(self <=> other) > 0</tt>:
 *
 *    'foo' > 'foo'  # => false
 *    'food' > 'foo' # => true
 */
 
static VALUE
cmp_gt(VALUE x, VALUE y)
{
    return RBOOL(cmpint(x, y) > 0);
}
 
/*
 *  call-seq:
 *    self >= other -> true or false
 *
 *  Returns whether +self+ is "greater than or equal to" +other+;
 *  equivalent to <tt>(self <=> other) >= 0</tt>:
 *
 *    'food' >= 'foo'  # => true
 *    'foo'  >= 'foo'  # => true
 *    'foo'  >= 'food' # => false
 *
 */
 
static VALUE
cmp_ge(VALUE x, VALUE y)
{
    return RBOOL(cmpint(x, y) >= 0);
}
 
/*
 *  call-seq:
 *    self < other -> true or false
 *
 *  Returns whether +self+ is "less than" +other+;
 *  equivalent to <tt>(self <=> other) < 0</tt>:
 *
 *    'foo' < 'foo'  # => false
 *    'foo' < 'food' # => true
 *
 */
 
static VALUE
cmp_lt(VALUE x, VALUE y)
{
    return RBOOL(cmpint(x, y) < 0);
}
 
/*
 *  call-seq:
 *    self <= other -> true or false
 *
 *  Returns whether +self+ is "less than or equal to" +other+;
 *  equivalent to <tt>(self <=> other) <= 0</tt>:
 *
 *    'foo' <= 'foo'  # => true
 *    'foo' <= 'food' # => true
 *    'food' <= 'foo' # => false
 *
 */
 
static VALUE
cmp_le(VALUE x, VALUE y)
{
    return RBOOL(cmpint(x, y) <= 0);
}
 
/*
 *  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)
{
    return RBOOL((cmpint(x, min) >= 0 && cmpint(x, max) <= 0));
}
 
/*
 *  :markup: markdown
 *
 *  call-seq:
 *    clamp(min, max) -> min, max, or self
 *    clamp(range) -> range.begin, range.end, or self
 *
 *  Returns an object of the same type as `self`.
 *
 *  With non-`nil` arguments `min` and `max` given, returns:
 *
 *  - `min`, if `self <= min`.
 *  - `max`, if `self >= max`.
 *  - `self`, otherwise.
 *
 *  Examples:
 *
 *  ```ruby
 *  0.clamp(0, 9)   # => 0
 *  -1.clamp(0, 9)  # => 0
 *  9.clamp(0, 9)   # => 9
 *  10.clamp(0, 9)  # => 9
 *  5.clamp(0, 9)   # => 5
 *  ```
 *
 *  With `nil` argument `min` given and non-`nil` argument `max` given, returns:
 *
 *  - `max`, if `self >= max`.
 *  - `self`, otherwise.
 *
 *  Examples:
 *
 *  ```ruby
 *  9.clamp(nil, 9)  # => 9
 *  10.clamp(nil, 9) # => 9
 *  0.clamp(nil, 9)  # => 0
 *  ```
 *
 *  With non-`nil` argument `min` and`nil` argument `max` given, returns:
 *
 *  - `min`, if `self <= min`.
 *  - `self`, otherwise.
 *
 *  Examples:
 *
 *  ```ruby
 *  0.clamp(0, nil)  # => 0
 *  -1.clamp(0, nil) # => 0
 *  1.clamp(0, nil)  # => 1
 *  ```
 *
 *  With `nil` arguments `min` and `max` given, returns `self`:
 *
 *  ```ruby
 *  0.clamp(nil, nil) # => 0
 *  0.clamp(nil, nil) # => 0
 *  ```
 *
 *  In all cases above, raises ArgumentError if comparison fails.
 *
 *  With [bounded range][bounded range] `range` given, returns:
 *
 *  - `range.begin`, if `self <= range.begin`.
 *  - `range.end`, if `self >= range.end`.
 *  - `self`, otherwise.
 *
 *  Examples:
 *
 *  ```ruby
 *  0.clamp(0..9)  # => 0
 *  -1.clamp(0..9) # => 0
 *  9.clamp(0..9)  # => 9
 *  10.clamp(0..9) # => 9
 *  5.clamp(0..9)  # => 5
 *  5.clamp(0...9) # Raises ArgumentError:cannot clamp with an exclusive range.
 *  ```
 *
 *  With [beginless range][beginless range] `range` given, returns:
 *
 *  - `range.end`, if `self >= range.end`.
 *  - `self`, otherwise.
 *
 *  Examples:
 *
 *  ```ruby
 *  9.clamp(nil..9)    # => 9
 *  10.clamp(nil..9)    # => 9
 *  0.clamp(nil..9)    # => 0
 *  0.clamp(nil...9) # Raises ArgumentError: cannot clamp with an exclusive range.
 *  ```
 *
 *  With [endless range][endless range] `range` given, returns:
 *
 *  - `range.begin`, if `self <= range.begin`.
 *  - `self`, otherwise.
 *
 *  Examples:
 *
 *  ```ruby
 *  0.clamp(0..nil)  # => 0
 *  -1.clamp(0..nil) # => 0
 *  1.clamp(0..nil)  # => 1
 *  1.clamp(0...nil) # => 1
 *  ```
 *
 *  With [unbounded range][unbounded range] `range` given, returns `self`:
 *
 *  ```ruby
 *  0.clamp(nil..nil)  # => 0
 *  0.clamp(nil...nil) # => 0
 *  ```
 *
 *  [bounded range]: rdoc-ref:Range@Bounded+Ranges
 *  [beginless range]: rdoc-ref:Range@Beginless+Ranges
 *  [endless range]: rdoc-ref:Range@Endless+Ranges
 *  [unbounded range]: rdoc-ref:Range@Unbounded+Ranges
 *
 */
 
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) && !NIL_P(max) && cmpint(min, max) > 0) {
        rb_raise(rb_eArgError, "min argument must be less than or equal to 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, returning 0, or returning 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 StringSorter
 *       include Comparable
 *
 *       attr :str
 *       def <=>(other)
 *         str.size <=> other.str.size
 *       end
 *
 *       def initialize(str)
 *         @str = str
 *       end
 *
 *       def inspect
 *         @str
 *       end
 *     end
 *
 *     s1 = StringSorter.new("Z")
 *     s2 = StringSorter.new("YY")
 *     s3 = StringSorter.new("XXX")
 *     s4 = StringSorter.new("WWWW")
 *     s5 = StringSorter.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]
 *
 *  == What's Here
 *
 *  Module \Comparable provides these methods, all of which use method <tt>#<=></tt>:
 *
 *  - #<: Returns whether +self+ is less than the given object.
 *  - #<=: Returns whether +self+ is less than or equal to the given object.
 *  - #==: Returns whether +self+ is equal to the given object.
 *  - #>: Returns whether +self+ is greater than the given object.
 *  - #>=: Returns whether +self+ is greater than or equal to the given object.
 *  - #between?: Returns +true+ if +self+ is between two given objects.
 *  - #clamp: For given objects +min+ and +max+, or range <tt>(min..max)</tt>, returns:
 *
 *    - +min+ if <tt>(self <=> min) < 0</tt>.
 *    - +max+ if <tt>(self <=> max) > 0</tt>.
 *    - +self+ otherwise.
 *
 */
 
void
Init_Comparable(void)
{
    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);
}