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Commit f1355c8d by Jonathan Wakely Committed by Jonathan Wakely
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libstdc++: Define std::lexicographical_compare_three_way for C++20 

	* include/bits/stl_algobase.h (lexicographical_compare_three_way):
	Define for C++20.
	* testsuite/25_algorithms/lexicographical_compare_three_way/1.cc: New
	test.
	* testsuite/25_algorithms/lexicographical_compare_three_way/
	constexpr.cc: New test.

From-SVN: r278996
parent 16e81d51
Showing with 302 additions and 0 deletions
libstdc++-v3/ChangeLog
2019-12-05 Jonathan Wakely <jwakely@redhat.com> 2019-12-05 Jonathan Wakely <jwakely@redhat.com>
* include/bits/stl_algobase.h (lexicographical_compare_three_way):
Define for C++20.
* testsuite/25_algorithms/lexicographical_compare_three_way/1.cc: New
test.
* testsuite/25_algorithms/lexicographical_compare_three_way/
constexpr.cc: New test.
* python/libstdcxx/v6/printers.py (StdCmpCatPrinter): New printer. * python/libstdcxx/v6/printers.py (StdCmpCatPrinter): New printer.
* testsuite/libstdc++-prettyprinters/cxx20.cc: New test. * testsuite/libstdc++-prettyprinters/cxx20.cc: New test.
......
libstdc++-v3/include/bits/stl_algobase.h
...@@ -72,6 +72,9 @@ ...@@ -72,6 +72,9 @@
#if __cplusplus >= 201103L #if __cplusplus >= 201103L
# include <type_traits> # include <type_traits>
#endif #endif
#if __cplusplus > 201703L
# include <compare>
#endif
namespace std _GLIBCXX_VISIBILITY(default) namespace std _GLIBCXX_VISIBILITY(default)
{ {
...@@ -1456,6 +1459,104 @@ _GLIBCXX_BEGIN_NAMESPACE_ALGO ...@@ -1456,6 +1459,104 @@ _GLIBCXX_BEGIN_NAMESPACE_ALGO
__gnu_cxx::__ops::__iter_comp_iter(__comp)); __gnu_cxx::__ops::__iter_comp_iter(__comp));
} }
#if __cpp_lib_three_way_comparison
#if __cpp_lib_concepts
// Iter points to a contiguous range of unsigned narrow character type
// or std::byte, suitable for comparison by memcmp.
template<typename _Iter>
concept __is_byte_iter = contiguous_iterator<_Iter>
&& __is_byte<iter_value_t<_Iter>>::__value != 0
&& !__gnu_cxx::__numeric_traits<iter_value_t<_Iter>>::__is_signed;
// Return a struct with two members, initialized to the smaller of x and y
// (or x if they compare equal) and the result of the comparison x <=> y.
template<typename _Tp>
constexpr auto
__min_cmp(_Tp __x, _Tp __y)
{
struct _Res {
_Tp _M_min;
decltype(__x <=> __y) _M_cmp;
};
auto __c = __x <=> __y;
if (__c > 0)
return _Res{__y, __c};
return _Res{__x, __c};
}
#endif
/**
* @brief Performs dictionary comparison on ranges.
* @ingroup sorting_algorithms
* @param __first1 An input iterator.
* @param __last1 An input iterator.
* @param __first2 An input iterator.
* @param __last2 An input iterator.
* @param __comp A @link comparison_functors comparison functor@endlink.
* @return The comparison category that `__comp(*__first1, *__first2)`
* returns.
*/
template<typename _InputIter1, typename _InputIter2, typename _Comp>
constexpr auto
lexicographical_compare_three_way(_InputIter1 __first1,
_InputIter1 __last1,
_InputIter2 __first2,
_InputIter2 __last2,
_Comp __comp)
-> decltype(__comp(*__first1, *__first2))
{
// concept requirements
__glibcxx_function_requires(_InputIteratorConcept<_InputIter1>)
__glibcxx_function_requires(_InputIteratorConcept<_InputIter2>)
__glibcxx_requires_valid_range(__first1, __last1);
__glibcxx_requires_valid_range(__first2, __last2);
#if __cpp_lib_concepts && __cpp_lib_is_constant_evaluated
using _Cat = decltype(__comp(*__first1, *__first2));
static_assert(same_as<common_comparison_category_t<_Cat>, _Cat>);
if (!std::is_constant_evaluated())
if constexpr (same_as<_Comp, __detail::_Synth3way>
|| same_as<_Comp, compare_three_way>)
if constexpr (__is_byte_iter<_InputIter1>)
if constexpr (__is_byte_iter<_InputIter2>)
{
const auto [__len, __lencmp]
= std::__min_cmp(__last1 - __first1, __last2 - __first2);
if (__len)
{
const auto __c
= __builtin_memcmp(&*__first1, &*__first2, __len) <=> 0;
if (__c != 0)
return __c;
}
return __lencmp;
}
#endif // concepts && is_constant_evaluated
while (__first1 != __last1 && __first2 != __last2)
{
if (auto __cmp = __comp(*__first1, *__first2); __cmp != 0)
return __cmp;
++__first1;
++__first2;
}
return __first1 != __last1 ? strong_ordering::greater
: __first2 != __last2 ? strong_ordering::less : strong_ordering::equal;
}
template<typename _InputIter1, typename _InputIter2>
constexpr auto
lexicographical_compare_three_way(_InputIter1 __first1,
_InputIter1 __last1,
_InputIter2 __first2,
_InputIter2 __last2)
{
return std::lexicographical_compare_three_way(__first1, __last1,
__first2, __last2,
compare_three_way{});
}
#endif // three_way_comparison
template<typename _InputIterator1, typename _InputIterator2, template<typename _InputIterator1, typename _InputIterator2,
typename _BinaryPredicate> typename _BinaryPredicate>
_GLIBCXX20_CONSTEXPR _GLIBCXX20_CONSTEXPR
......
libstdc++-v3/testsuite/25_algorithms/lexicographical_compare_three_way/1.cc 0 → 100644
// Copyright (C) 2019 Free Software Foundation, Inc.
//
// 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
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 3, or (at your option)
// any later version.
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// You should have received a copy of the GNU General Public License along
// with this library; see the file COPYING3. If not see
// <http://www.gnu.org/licenses/>.
// { dg-options "-std=gnu++2a" }
// { dg-do run { target c++2a } }
#include <algorithm>
#include <testsuite_hooks.h>
#include <testsuite_iterators.h>
// Lambda that calls lexicographical_compare_three_way on two ranges.
// Arguments are passed by value intentionally, so that a copy of the range
// is traversed and the original is not modified. Otherwise when the range
// has input iterators the range will be consumed after the first comparison.
auto lexicomp3 = [](auto r1, auto r2) {
return std::lexicographical_compare_three_way(r1.begin(), r1.end(),
r2.begin(), r2.end());
};
void
test01()
{
using __gnu_test::test_container;
using __gnu_test::input_iterator_wrapper;
using __gnu_test::forward_iterator_wrapper;
int arr1[] = { 0, 1, 2, 3, 4, 5, 6, 7 };
int arr2[] = { 0, 1, 2, 3, 4, 5, 6, 777 };
{
test_container<int, input_iterator_wrapper> c1(arr1);
test_container<int, input_iterator_wrapper> c2(arr2);
VERIFY( lexicomp3(c1, c1) == 0 );
VERIFY( lexicomp3(c1, c2) < 0 );
VERIFY( lexicomp3(c2, c1) > 0 );
}
{
test_container<int, input_iterator_wrapper> c1(arr1, arr1+6);
test_container<int, input_iterator_wrapper> c2(arr2, arr2+6);
VERIFY( lexicomp3(c1, c1) == 0 );
VERIFY( lexicomp3(c1, c2) == 0 );
VERIFY( lexicomp3(c2, c1) == 0 );
}
{
test_container<int, input_iterator_wrapper> c1(arr1);
test_container<int, input_iterator_wrapper> c2(arr2, arr2+7);
VERIFY( lexicomp3(c1, c1) == 0 );
VERIFY( lexicomp3(c1, c2) > 0 );
VERIFY( lexicomp3(c2, c1) < 0 );
}
{
test_container<int, input_iterator_wrapper> c1(arr1);
test_container<int, forward_iterator_wrapper> c2(arr2);
VERIFY( lexicomp3(c1, c1) == 0 );
VERIFY( lexicomp3(c1, c2) < 0 );
VERIFY( lexicomp3(c2, c1) > 0 );
}
{
test_container<int, input_iterator_wrapper> c1(arr1);
test_container<int, forward_iterator_wrapper> c2(arr2, arr2+7);
VERIFY( lexicomp3(c1, c1) == 0 );
VERIFY( lexicomp3(c2, c2) == 0 );
VERIFY( lexicomp3(c1, c2) > 0 );
VERIFY( lexicomp3(c2, c1) < 0 );
}
{
test_container<int, forward_iterator_wrapper> c1(arr1, arr1+7);
test_container<int, input_iterator_wrapper> c2(arr2);
VERIFY( lexicomp3(c1, c1) == 0 );
VERIFY( lexicomp3(c2, c2) == 0 );
VERIFY( lexicomp3(c1, c2) < 0 );
VERIFY( lexicomp3(c2, c1) > 0 );
}
}
void
test02()
{
using __gnu_test::test_container;
using __gnu_test::input_iterator_wrapper;
using __gnu_test::forward_iterator_wrapper;
std::array<unsigned char, 8> c1 = { 0, 1, 2, 3, 4, 5, 6, 7 };
std::array<unsigned char, 8> c2 = { 0, 1, 2, 3, 4, 5, 6, 77 };
VERIFY( lexicomp3(c1, c1) == 0 );
VERIFY( lexicomp3(c1, c2) < 0 );
VERIFY( lexicomp3(c2, c1) > 0 );
std::array<unsigned char, 7> c3 = { 0, 1, 2, 3, 4, 5, 6 };
VERIFY( lexicomp3(c3, c3) == 0 );
VERIFY( lexicomp3(c1, c3) > 0 );
VERIFY( lexicomp3(c3, c1) < 0 );
}
void
test03()
{
unsigned char a[2] = { 1, 2 };
unsigned char* p = nullptr;
// ensure memcmp not called with nullptr
VERIFY( std::lexicographical_compare_three_way(p, p, a, a+2) < 0 );
VERIFY( std::lexicographical_compare_three_way(a, a+2, p, p) > 0 );
}
int
main()
{
test01();
test02();
test03();
}
libstdc++-v3/testsuite/25_algorithms/lexicographical_compare_three_way/constexpr.cc 0 → 100644
// Copyright (C) 2019 Free Software Foundation, Inc.
//
// 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
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 3, or (at your option)
// any later version.
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// You should have received a copy of the GNU General Public License along
// with this library; see the file COPYING3. If not see
// <http://www.gnu.org/licenses/>.
// { dg-options "-std=gnu++2a" }
// { dg-do compile { target c++2a } }
#include <algorithm>
constexpr bool
test01(int i)
{
int a1[] = { 0, 1, 2, 3, 4, 5, 6, i, 8 };
long a2[] = { 0, 1, 2, 3, 4, 5, 6, 7, 8 };
return std::lexicographical_compare_three_way(a1, a1+0, a2, a2+0) == 0
&& std::lexicographical_compare_three_way(a1, a1+9, a2, a2+9) == (i <=> 7)
&& std::lexicographical_compare_three_way(a1, a1+7, a2, a2+7) == 0
&& std::lexicographical_compare_three_way(a1, a1+8, a2, a2+7) > 0
&& std::lexicographical_compare_three_way(a1, a1+7, a2, a2+8) < 0;
}
static_assert( test01(~7) );
static_assert( test01(7) );
static_assert( test01(8) );
constexpr bool
test02(unsigned char i)
{
unsigned char a1[] = { 0, 1, 2, 3, 4, 5, 6, i, 8 };
unsigned char a2[] = { 0, 1, 2, 3, 4, 5, 6, 7, 8 };
return std::lexicographical_compare_three_way(a1, a1+0, a2, a2+0) == 0
&& std::lexicographical_compare_three_way(a1, a1+9, a2, a2+9) == (i <=> 7)
&& std::lexicographical_compare_three_way(a1, a1+7, a2, a2+7) == 0
&& std::lexicographical_compare_three_way(a1, a1+8, a2, a2+7) > 0
&& std::lexicographical_compare_three_way(a1, a1+7, a2, a2+8) < 0;
}
static_assert( test02(248) );
static_assert( test02(7) );
static_assert( test02(8) );
constexpr bool
test03(unsigned char* p)
{
unsigned char a[2] = { 1, 2 };
return std::lexicographical_compare_three_way(p, p, a, a+2) < 0
&& std::lexicographical_compare_three_way(a, a+2, p, p) > 0;
}
static_assert( test03(nullptr) ); // ensure memcmp not called with nullptr
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