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/*!
@file
Defines several `constexpr` algorithms.
@copyright Louis Dionne 2013-2016
Distributed under the Boost Software License, Version 1.0.
(See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
*/
#ifndef BOOST_HANA_DETAIL_ALGORITHM_HPP
#define BOOST_HANA_DETAIL_ALGORITHM_HPP
#include <boost/hana/functional/placeholder.hpp>
#include <boost/hana/config.hpp>
#include <cstddef>
#include <utility>
BOOST_HANA_NAMESPACE_BEGIN namespace detail {
// Do not call this swap, otherwise it can get picked up by ADL and conflict
// with std::swap (see https://github.com/boostorg/hana/issues/297).
template <typename T>
constexpr void constexpr_swap(T& x, T& y) {
auto tmp = x;
x = y;
y = std::move(tmp);
}
template <typename BidirIter>
constexpr void reverse(BidirIter first, BidirIter last) {
while (first != last) {
if (first == --last)
break;
detail::constexpr_swap(*first, *last);
++first;
}
}
template <typename BidirIter, typename BinaryPred>
constexpr bool next_permutation(BidirIter first, BidirIter last,
BinaryPred pred)
{
BidirIter i = last;
if (first == last || first == --i)
return false;
while (true) {
BidirIter ip1 = i;
if (pred(*--i, *ip1)) {
BidirIter j = last;
while (!pred(*i, *--j))
;
detail::constexpr_swap(*i, *j);
detail::reverse(ip1, last);
return true;
}
if (i == first) {
detail::reverse(first, last);
return false;
}
}
}
template <typename BidirIter>
constexpr bool next_permutation(BidirIter first, BidirIter last)
{ return detail::next_permutation(first, last, hana::_ < hana::_); }
template <typename InputIter1, typename InputIter2, typename BinaryPred>
constexpr bool lexicographical_compare(InputIter1 first1, InputIter1 last1,
InputIter2 first2, InputIter2 last2,
BinaryPred pred)
{
for (; first2 != last2; ++first1, ++first2) {
if (first1 == last1 || pred(*first1, *first2))
return true;
else if (pred(*first2, *first1))
return false;
}
return false;
}
template <typename InputIter1, typename InputIter2>
constexpr bool lexicographical_compare(InputIter1 first1, InputIter1 last1,
InputIter2 first2, InputIter2 last2)
{ return detail::lexicographical_compare(first1, last1, first2, last2, hana::_ < hana::_); }
template <typename InputIter1, typename InputIter2, typename BinaryPred>
constexpr bool equal(InputIter1 first1, InputIter1 last1,
InputIter2 first2, InputIter2 last2,
BinaryPred pred)
{
for (; first1 != last1 && first2 != last2; ++first1, ++first2)
if (!pred(*first1, *first2))
return false;
return first1 == last1 && first2 == last2;
}
template <typename InputIter1, typename InputIter2>
constexpr bool equal(InputIter1 first1, InputIter1 last1,
InputIter2 first2, InputIter2 last2)
{ return detail::equal(first1, last1, first2, last2, hana::_ == hana::_); }
template <typename BidirIter, typename BinaryPred>
constexpr void sort(BidirIter first, BidirIter last, BinaryPred pred) {
if (first == last) return;
BidirIter i = first;
for (++i; i != last; ++i) {
BidirIter j = i;
auto t = *j;
for (BidirIter k = i; k != first && pred(t, *--k); --j)
*j = *k;
*j = t;
}
}
template <typename BidirIter>
constexpr void sort(BidirIter first, BidirIter last)
{ detail::sort(first, last, hana::_ < hana::_); }
template <typename InputIter, typename T>
constexpr InputIter find(InputIter first, InputIter last, T const& value) {
for (; first != last; ++first)
if (*first == value)
return first;
return last;
}
template <typename InputIter, typename UnaryPred>
constexpr InputIter find_if(InputIter first, InputIter last, UnaryPred pred) {
for (; first != last; ++first)
if (pred(*first))
return first;
return last;
}
template <typename ForwardIter, typename T>
constexpr void iota(ForwardIter first, ForwardIter last, T value) {
while (first != last) {
*first++ = value;
++value;
}
}
template <typename InputIt, typename T>
constexpr std::size_t
count(InputIt first, InputIt last, T const& value) {
std::size_t n = 0;
for (; first != last; ++first)
if (*first == value)
++n;
return n;
}
template <typename InputIt, typename T, typename F>
constexpr T accumulate(InputIt first, InputIt last, T init, F f) {
for (; first != last; ++first)
init = f(init, *first);
return init;
}
template <typename InputIt, typename T>
constexpr T accumulate(InputIt first, InputIt last, T init) {
return detail::accumulate(first, last, init, hana::_ + hana::_);
}
template <typename ForwardIt>
constexpr ForwardIt min_element(ForwardIt first, ForwardIt last) {
if (first == last)
return last;
ForwardIt smallest = first;
++first;
for (; first != last; ++first)
if (*first < *smallest)
smallest = first;
return smallest;
}
} BOOST_HANA_NAMESPACE_END
#endif // !BOOST_HANA_DETAIL_ALGORITHM_HPP
|
