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ratio (ratio_less): Improve, use ratio_divide to avoid more overflows.

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2010-08-06  Paolo Carlini  <paolo.carlini@oracle.com>

	* include/std/ratio (ratio_less): Improve, use ratio_divide to avoid
	more overflows.
	* testsuite/20_util/ratio/comparisons/comp1.cc: Extend.
	* testsuite/20_util/ratio/comparisons/comp2.cc: Likewise.

From-SVN: r162941
This commit is contained in:
Paolo Carlini 2010-08-06 08:58:27 +00:00 committed by Paolo Carlini
parent 0af2372948
commit cd6b4a4bca
4 changed files with 43 additions and 17 deletions
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7
libstdc++-v3/ChangeLog
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@ -1,3 +1,10 @@
2010-08-06 Paolo Carlini <paolo.carlini@oracle.com>
* include/std/ratio (ratio_less): Improve, use ratio_divide to avoid
more overflows.
* testsuite/20_util/ratio/comparisons/comp1.cc: Extend.
* testsuite/20_util/ratio/comparisons/comp2.cc: Likewise.
2010-08-05 Paolo Carlini <paolo.carlini@oracle.com>
* include/tr1_impl/utility (begin, end): Remove per GB 85.

35
libstdc++-v3/include/std/ratio
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@ -233,23 +233,30 @@ namespace std
struct ratio_not_equal
: integral_constant<bool, !ratio_equal<_R1, _R2>::value>
{ };
template<typename _R1, typename _R2>
struct __ratio_less_simple_impl
: integral_constant<bool,
(__safe_multiply<_R1::num, _R2::den>::value
< __safe_multiply<_R2::num, _R1::den>::value)>
{ };
// If the denominators are equal or the signs differ, we can just compare
// numerators, otherwise fallback to the simple cross-multiply method.
template<typename _R1, typename _R2>
struct __ratio_less_impl
: conditional<(_R1::den == _R2::den
template<typename _R1>
struct __ratio_less_impl_1
: integral_constant<bool, _R1::num < _R1::den>
{ };
template<typename _R1, typename _R2,
bool = (_R1::num == 0 || _R2::num == 0
|| (__static_sign<_R1::num>::value
!= __static_sign<_R2::num>::value)),
integral_constant<bool, (_R1::num < _R2::num)>,
__ratio_less_simple_impl<_R1, _R2>>::type
bool = (__static_sign<_R1::num>::value == -1
&& __static_sign<_R2::num>::value == -1)>
struct __ratio_less_impl
: __ratio_less_impl_1<typename ratio_divide<_R1, _R2>::type>::type
{ };
template<typename _R1, typename _R2>
struct __ratio_less_impl<_R1, _R2, true, false>
: integral_constant<bool, _R1::num < _R2::num>
{ };
template<typename _R1, typename _R2>
struct __ratio_less_impl<_R1, _R2, false, true>
: __ratio_less_impl_1<typename ratio_divide<_R2, _R1>::type>::type
{ };
/// ratio_less

9
libstdc++-v3/testsuite/20_util/ratio/comparisons/comp1.cc
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@ -1,7 +1,7 @@
// { dg-options "-std=gnu++0x" }
// { dg-require-cstdint "" }
// Copyright (C) 2008, 2009 Free Software Foundation
// Copyright (C) 2008, 2009, 2010 Free Software Foundation
//
// This file is part of the GNU ISO C++ Library. This library is free
// software; you can redistribute it and/or modify it under the
@ -45,7 +45,12 @@ test02()
VERIFY( (std::ratio_less<std::ratio<1,3>, std::ratio<1,4>>::value == 0) );
VERIFY( (std::ratio_less<std::ratio<1,3>, std::ratio<-1,3>>::value == 0) );
VERIFY( (std::ratio_less<std::ratio<-1,3>, std::ratio<-1,4>>::value == 1) );
VERIFY( (std::ratio_less<std::ratio<0,4>, std::ratio<0,3>>::value == 0) );
VERIFY( (std::ratio_less<std::ratio<1,3>, std::ratio<0,3>>::value == 0) );
VERIFY( (std::ratio_less<std::ratio<0,3>, std::ratio<-1,4>>::value == 0) );
VERIFY( (std::ratio_less_equal<std::ratio<-1,3>,
std::ratio<-1,3>>::value == 1) );
VERIFY( ( std::ratio_less_equal<std::ratio<1,4>,

9
libstdc++-v3/testsuite/20_util/ratio/comparisons/comp2.cc
View File

@ -1,7 +1,7 @@
// { dg-options "-std=gnu++0x" }
// { dg-require-cstdint "" }
// Copyright (C) 2008, 2009 Free Software Foundation
// Copyright (C) 2008, 2009, 2010 Free Software Foundation
//
// This file is part of the GNU ISO C++ Library. This library is free
// software; you can redistribute it and/or modify it under the
@ -41,6 +41,13 @@ test01()
VERIFY( (std::ratio_less<std::ratio<M - 1, M - 2>,
std::ratio<-M, M - 1>>::value == 0) );
// No overflow
VERIFY( (std::ratio_less<std::ratio<M, M - 1>,
std::ratio<M, M - 2>>::value == 1) );
VERIFY( (std::ratio_less<std::ratio<-M, M - 1>,
std::ratio<-M, M - 2>>::value == 0) );
}
int main()