Implement LWG2350: min, max, and minmax should be constexpr.
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@201697 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/algorithm b/include/algorithm
index 367489f..b022f31 100644
--- a/include/algorithm
+++ b/include/algorithm
@@ -528,19 +528,19 @@
template <class T>
const T&
- min(const T& a, const T& b);
+ min(const T& a, const T& b); // constexpr in C++14
template <class T, class Compare>
const T&
- min(const T& a, const T& b, Compare comp);
+ min(const T& a, const T& b, Compare comp); // constexpr in C++14
template<class T>
T
- min(initializer_list<T> t);
+ min(initializer_list<T> t); // constexpr in C++14
template<class T, class Compare>
T
- min(initializer_list<T> t, Compare comp);
+ min(initializer_list<T> t, Compare comp); // constexpr in C++14
template <class ForwardIterator>
ForwardIterator
@@ -552,19 +552,19 @@
template <class T>
const T&
- max(const T& a, const T& b);
+ max(const T& a, const T& b); // constexpr in C++14
template <class T, class Compare>
const T&
- max(const T& a, const T& b, Compare comp);
+ max(const T& a, const T& b, Compare comp); // constexpr in C++14
template<class T>
T
- max(initializer_list<T> t);
+ max(initializer_list<T> t); // constexpr in C++14
template<class T, class Compare>
T
- max(initializer_list<T> t, Compare comp);
+ max(initializer_list<T> t, Compare comp); // constexpr in C++14
template<class ForwardIterator>
pair<ForwardIterator, ForwardIterator>
@@ -576,19 +576,19 @@
template<class T>
pair<const T&, const T&>
- minmax(const T& a, const T& b);
+ minmax(const T& a, const T& b); // constexpr in C++14
template<class T, class Compare>
pair<const T&, const T&>
- minmax(const T& a, const T& b, Compare comp);
+ minmax(const T& a, const T& b, Compare comp); // constexpr in C++14
template<class T>
pair<T, T>
- minmax(initializer_list<T> t);
+ minmax(initializer_list<T> t); // constexpr in C++14
template<class T, class Compare>
pair<T, T>
- minmax(initializer_list<T> t, Compare comp);
+ minmax(initializer_list<T> t, Compare comp); // constexpr in C++14
template <class InputIterator1, class InputIterator2>
bool
@@ -643,6 +643,9 @@
_LIBCPP_BEGIN_NAMESPACE_STD
+// I'd like to replace these with _VSTD::equal_to<void>, but can't because:
+// * That only works with C++14 and later, and
+// * We haven't included <functional> here.
template <class _T1, class _T2 = _T1>
struct __equal_to
{
@@ -655,46 +658,59 @@
template <class _T1>
struct __equal_to<_T1, _T1>
{
- _LIBCPP_INLINE_VISIBILITY bool operator()(const _T1& __x, const _T1& __y) const {return __x == __y;}
+ _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+ bool operator()(const _T1& __x, const _T1& __y) const {return __x == __y;}
};
template <class _T1>
struct __equal_to<const _T1, _T1>
{
- _LIBCPP_INLINE_VISIBILITY bool operator()(const _T1& __x, const _T1& __y) const {return __x == __y;}
+ _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+ bool operator()(const _T1& __x, const _T1& __y) const {return __x == __y;}
};
template <class _T1>
struct __equal_to<_T1, const _T1>
{
- _LIBCPP_INLINE_VISIBILITY bool operator()(const _T1& __x, const _T1& __y) const {return __x == __y;}
+ _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+ bool operator()(const _T1& __x, const _T1& __y) const {return __x == __y;}
};
template <class _T1, class _T2 = _T1>
struct __less
{
- _LIBCPP_INLINE_VISIBILITY bool operator()(const _T1& __x, const _T1& __y) const {return __x < __y;}
- _LIBCPP_INLINE_VISIBILITY bool operator()(const _T1& __x, const _T2& __y) const {return __x < __y;}
- _LIBCPP_INLINE_VISIBILITY bool operator()(const _T2& __x, const _T1& __y) const {return __x < __y;}
- _LIBCPP_INLINE_VISIBILITY bool operator()(const _T2& __x, const _T2& __y) const {return __x < __y;}
+ _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+ bool operator()(const _T1& __x, const _T1& __y) const {return __x < __y;}
+
+ _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+ bool operator()(const _T1& __x, const _T2& __y) const {return __x < __y;}
+
+ _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+ bool operator()(const _T2& __x, const _T1& __y) const {return __x < __y;}
+
+ _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+ bool operator()(const _T2& __x, const _T2& __y) const {return __x < __y;}
};
template <class _T1>
struct __less<_T1, _T1>
{
- _LIBCPP_INLINE_VISIBILITY bool operator()(const _T1& __x, const _T1& __y) const {return __x < __y;}
+ _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+ bool operator()(const _T1& __x, const _T1& __y) const {return __x < __y;}
};
template <class _T1>
struct __less<const _T1, _T1>
{
- _LIBCPP_INLINE_VISIBILITY bool operator()(const _T1& __x, const _T1& __y) const {return __x < __y;}
+ _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+ bool operator()(const _T1& __x, const _T1& __y) const {return __x < __y;}
};
template <class _T1>
struct __less<_T1, const _T1>
{
- _LIBCPP_INLINE_VISIBILITY bool operator()(const _T1& __x, const _T1& __y) const {return __x < __y;}
+ _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+ bool operator()(const _T1& __x, const _T1& __y) const {return __x < __y;}
};
template <class _Predicate>
@@ -2505,9 +2521,9 @@
// min_element
template <class _ForwardIterator, class _Compare>
-inline _LIBCPP_INLINE_VISIBILITY
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
_ForwardIterator
-min_element(_ForwardIterator __first, _ForwardIterator __last, _Compare __comp)
+__min_element(_ForwardIterator __first, _ForwardIterator __last, _Compare __comp)
{
if (__first != __last)
{
@@ -2519,19 +2535,27 @@
return __first;
}
+template <class _ForwardIterator, class _Compare>
+inline _LIBCPP_INLINE_VISIBILITY
+_ForwardIterator
+min_element(_ForwardIterator __first, _ForwardIterator __last, _Compare __comp)
+{
+ return __min_element(__first, __last, __comp);
+}
+
template <class _ForwardIterator>
inline _LIBCPP_INLINE_VISIBILITY
_ForwardIterator
min_element(_ForwardIterator __first, _ForwardIterator __last)
{
- return _VSTD::min_element(__first, __last,
+ return __min_element(__first, __last,
__less<typename iterator_traits<_ForwardIterator>::value_type>());
}
// min
template <class _Tp, class _Compare>
-inline _LIBCPP_INLINE_VISIBILITY
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
const _Tp&
min(const _Tp& __a, const _Tp& __b, _Compare __comp)
{
@@ -2539,7 +2563,7 @@
}
template <class _Tp>
-inline _LIBCPP_INLINE_VISIBILITY
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
const _Tp&
min(const _Tp& __a, const _Tp& __b)
{
@@ -2549,19 +2573,19 @@
#ifndef _LIBCPP_HAS_NO_GENERALIZED_INITIALIZERS
template<class _Tp, class _Compare>
-inline _LIBCPP_INLINE_VISIBILITY
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
_Tp
min(initializer_list<_Tp> __t, _Compare __comp)
{
- return *_VSTD::min_element(__t.begin(), __t.end(), __comp);
+ return *__min_element(__t.begin(), __t.end(), __comp);
}
template<class _Tp>
-inline _LIBCPP_INLINE_VISIBILITY
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
_Tp
min(initializer_list<_Tp> __t)
{
- return *_VSTD::min_element(__t.begin(), __t.end());
+ return *__min_element(__t.begin(), __t.end(), __less<_Tp>());
}
#endif // _LIBCPP_HAS_NO_GENERALIZED_INITIALIZERS
@@ -2569,9 +2593,9 @@
// max_element
template <class _ForwardIterator, class _Compare>
-inline _LIBCPP_INLINE_VISIBILITY
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
_ForwardIterator
-max_element(_ForwardIterator __first, _ForwardIterator __last, _Compare __comp)
+__max_element(_ForwardIterator __first, _ForwardIterator __last, _Compare __comp)
{
if (__first != __last)
{
@@ -2583,19 +2607,28 @@
return __first;
}
+
+template <class _ForwardIterator, class _Compare>
+inline _LIBCPP_INLINE_VISIBILITY
+_ForwardIterator
+max_element(_ForwardIterator __first, _ForwardIterator __last, _Compare __comp)
+{
+ return __max_element(__first, __last, __comp);
+}
+
template <class _ForwardIterator>
inline _LIBCPP_INLINE_VISIBILITY
_ForwardIterator
max_element(_ForwardIterator __first, _ForwardIterator __last)
{
- return _VSTD::max_element(__first, __last,
+ return __max_element(__first, __last,
__less<typename iterator_traits<_ForwardIterator>::value_type>());
}
// max
template <class _Tp, class _Compare>
-inline _LIBCPP_INLINE_VISIBILITY
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
const _Tp&
max(const _Tp& __a, const _Tp& __b, _Compare __comp)
{
@@ -2603,7 +2636,7 @@
}
template <class _Tp>
-inline _LIBCPP_INLINE_VISIBILITY
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
const _Tp&
max(const _Tp& __a, const _Tp& __b)
{
@@ -2613,19 +2646,19 @@
#ifndef _LIBCPP_HAS_NO_GENERALIZED_INITIALIZERS
template<class _Tp, class _Compare>
-inline _LIBCPP_INLINE_VISIBILITY
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
_Tp
max(initializer_list<_Tp> __t, _Compare __comp)
{
- return *_VSTD::max_element(__t.begin(), __t.end(), __comp);
+ return *__max_element(__t.begin(), __t.end(), __comp);
}
template<class _Tp>
-inline _LIBCPP_INLINE_VISIBILITY
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
_Tp
max(initializer_list<_Tp> __t)
{
- return *_VSTD::max_element(__t.begin(), __t.end());
+ return *__max_element(__t.begin(), __t.end(), __less<_Tp>());
}
#endif // _LIBCPP_HAS_NO_GENERALIZED_INITIALIZERS
@@ -2684,13 +2717,14 @@
std::pair<_ForwardIterator, _ForwardIterator>
minmax_element(_ForwardIterator __first, _ForwardIterator __last)
{
- return _VSTD::minmax_element(__first, __last, __less<typename iterator_traits<_ForwardIterator>::value_type>());
+ return _VSTD::minmax_element(__first, __last,
+ __less<typename iterator_traits<_ForwardIterator>::value_type>());
}
// minmax
template<class _Tp, class _Compare>
-inline _LIBCPP_INLINE_VISIBILITY
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
pair<const _Tp&, const _Tp&>
minmax(const _Tp& __a, const _Tp& __b, _Compare __comp)
{
@@ -2699,7 +2733,7 @@
}
template<class _Tp>
-inline _LIBCPP_INLINE_VISIBILITY
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
pair<const _Tp&, const _Tp&>
minmax(const _Tp& __a, const _Tp& __b)
{
@@ -2708,24 +2742,49 @@
#ifndef _LIBCPP_HAS_NO_GENERALIZED_INITIALIZERS
-template<class _Tp>
-inline _LIBCPP_INLINE_VISIBILITY
-pair<_Tp, _Tp>
-minmax(initializer_list<_Tp> __t)
-{
- pair<const _Tp*, const _Tp*> __p =
- _VSTD::minmax_element(__t.begin(), __t.end());
- return pair<_Tp, _Tp>(*__p.first, *__p.second);
-}
-
template<class _Tp, class _Compare>
-inline _LIBCPP_INLINE_VISIBILITY
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
pair<_Tp, _Tp>
minmax(initializer_list<_Tp> __t, _Compare __comp)
{
- pair<const _Tp*, const _Tp*> __p =
- _VSTD::minmax_element(__t.begin(), __t.end(), __comp);
- return pair<_Tp, _Tp>(*__p.first, *__p.second);
+ typedef typename initializer_list<_Tp>::const_iterator _Iter;
+ _Iter __first = __t.begin();
+ _Iter __last = __t.end();
+ std::pair<_Tp, _Tp> __result ( *__first, *__first );
+
+ ++__first;
+ if (__t.size() % 2 == 0)
+ {
+ if (__comp(*__first, __result.first))
+ __result.first = *__first;
+ else
+ __result.second = *__first;
+ ++__first;
+ }
+
+ while (__first != __last)
+ {
+ _Tp __prev = *__first++;
+ if (__comp(__prev, *__first)) {
+ if (__comp(__prev, __result.first)) __result.first = __prev;
+ if (__comp(__result.second, *__first)) __result.second = *__first;
+ }
+ else {
+ if (__comp(*__first, __result.first)) __result.first = *__first;
+ if (__comp(__result.second, __prev)) __result.second = __prev;
+ }
+
+ __first++;
+ }
+ return __result;
+}
+
+template<class _Tp>
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
+pair<_Tp, _Tp>
+minmax(initializer_list<_Tp> __t)
+{
+ return _VSTD::minmax(__t, __less<_Tp>());
}
#endif // _LIBCPP_HAS_NO_GENERALIZED_INITIALIZERS