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/// \file
// Range v3 library
//
// Copyright Eric Niebler 2014-present
//
// Use, modification and distribution is subject to the
// Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
//
// Project home: https://github.com/ericniebler/range-v3
//
#ifndef RANGES_V3_ALGORITHM_FIND_END_HPP
#define RANGES_V3_ALGORITHM_FIND_END_HPP
#include <utility>
#include <meta/meta.hpp>
#include <range/v3/range_fwd.hpp>
#include <range/v3/functional/comparisons.hpp>
#include <range/v3/functional/identity.hpp>
#include <range/v3/functional/invoke.hpp>
#include <range/v3/iterator/concepts.hpp>
#include <range/v3/iterator/operations.hpp>
#include <range/v3/iterator/traits.hpp>
#include <range/v3/range/access.hpp>
#include <range/v3/range/concepts.hpp>
#include <range/v3/range/traits.hpp>
#include <range/v3/utility/static_const.hpp>
#include <range/v3/view/subrange.hpp>
#include <range/v3/detail/prologue.hpp>
namespace ranges
{
/// \cond
namespace detail
{
template(typename I, typename S)(
requires input_iterator<I> AND sentinel_for<S, I>)
constexpr I next_to_if(I i, S s, std::true_type)
{
return ranges::next(i, s);
}
template(typename I, typename S)(
requires input_iterator<I> AND sentinel_for<S, I>)
constexpr S next_to_if(I, S s, std::false_type)
{
return s;
}
template(bool B, typename I, typename S)(
requires input_iterator<I> AND sentinel_for<S, I>)
constexpr meta::if_c<B, I, S> next_to_if(I i, S s)
{
return detail::next_to_if(std::move(i), std::move(s), meta::bool_<B>{});
}
template<typename I1, typename S1, typename I2, typename S2, typename R,
typename P>
constexpr subrange<I1> find_end_impl(I1 begin1, S1 end1, I2 begin2, S2 end2, R pred, P proj,
std::forward_iterator_tag, std::forward_iterator_tag)
{
bool found = false;
I1 res_begin, res_end;
if(begin2 == end2)
{
auto e1 = ranges::next(begin1, end1);
return {e1, e1};
}
while(true)
{
while(true)
{
if(begin1 == end1)
return {(found ? res_begin : begin1), (found ? res_end : begin1)};
if(invoke(pred, invoke(proj, *begin1), *begin2))
break;
++begin1;
}
auto tmp1 = begin1;
auto tmp2 = begin2;
while(true)
{
if(++tmp2 == end2)
{
res_begin = begin1++;
res_end = ++tmp1;
found = true;
break;
}
if(++tmp1 == end1)
return {(found ? res_begin : tmp1), (found ? res_end : tmp1)};
if(!invoke(pred, invoke(proj, *tmp1), *tmp2))
{
++begin1;
break;
}
}
}
}
template<typename I1, typename I2, typename R, typename P>
constexpr subrange<I1> find_end_impl(I1 begin1, I1 end1, I2 begin2, I2 end2, R pred, P proj,
std::bidirectional_iterator_tag,
std::bidirectional_iterator_tag)
{
// modeled after search algorithm (in reverse)
if(begin2 == end2)
return {end1, end1}; // Everything matches an empty sequence
I1 l1 = end1;
I2 l2 = end2;
--l2;
while(true)
{
// Find end element in sequence 1 that matches *(end2-1), with a mininum
// of loop checks
do
// return {end1,end1} if no element matches *begin2
if(begin1 == l1)
return {end1, end1};
while(!invoke(pred, invoke(proj, *--l1), *l2));
// *l1 matches *l2, now match elements before here
I1 m1 = l1;
I2 m2 = l2;
do
// If pattern exhausted, {m1,++l1} is the answer
// (works for 1 element pattern)
if(m2 == begin2)
return {m1, ++l1};
// Otherwise if source exhausted, pattern not found
else if(m1 == begin1)
return {end1, end1};
// if there is a mismatch, restart with a new l1
// else there is a match, check next elements
while(invoke(pred, invoke(proj, *--m1), *--m2));
}
}
template<typename I1, typename I2, typename R, typename P>
constexpr subrange<I1> find_end_impl(I1 begin1, I1 end1, I2 begin2, I2 end2, R pred, P proj,
std::random_access_iterator_tag,
std::random_access_iterator_tag)
{
// Take advantage of knowing source and pattern lengths. Stop short when
// source is smaller than pattern
auto len2 = end2 - begin2;
if(len2 == 0)
return {end1, end1};
auto len1 = end1 - begin1;
if(len1 < len2)
return {end1, end1};
I1 const start =
begin1 + (len2 - 1); // End of pattern match can't go before here
I1 l1 = end1;
I2 l2 = end2;
--l2;
while(true)
{
do
if(start == l1)
return {end1, end1};
while(!invoke(pred, invoke(proj, *--l1), *l2));
I1 m1 = l1;
I2 m2 = l2;
do
if(m2 == begin2)
return {m1, ++l1};
// no need to check range on m1 because s guarantees we have enough source
while(invoke(pred, invoke(proj, *--m1), *--m2));
}
}
} // namespace detail
/// \endcond
/// \addtogroup group-algorithms
/// @{
RANGES_FUNC_BEGIN(find_end)
/// \brief function template \c find_end
template(typename I1,
typename S1,
typename I2,
typename S2,
typename R = equal_to,
typename P = identity)(
requires forward_iterator<I1> AND sentinel_for<S1, I1> AND
forward_iterator<I2> AND sentinel_for<S2, I2> AND
indirect_relation<R, projected<I1, P>, I2>)
constexpr subrange<I1> RANGES_FUNC(find_end)(
I1 begin1, S1 end1, I2 begin2, S2 end2, R pred = R{}, P proj = P{}) //
{
constexpr bool Bidi =
bidirectional_iterator<I1> && bidirectional_iterator<I2>;
return detail::find_end_impl(begin1,
detail::next_to_if<Bidi>(begin1, end1),
begin2,
detail::next_to_if<Bidi>(begin2, end2),
std::move(pred),
std::move(proj),
iterator_tag_of<I1>(),
iterator_tag_of<I2>());
}
/// \overload
template(typename Rng1,
typename Rng2,
typename R = equal_to,
typename P = identity)(
requires forward_range<Rng1> AND forward_range<Rng2> AND
indirect_relation<R, projected<iterator_t<Rng1>, P>, iterator_t<Rng2>>)
constexpr borrowed_subrange_t<Rng1> RANGES_FUNC(find_end)(
Rng1 && rng1, Rng2 && rng2, R pred = R{}, P proj = P{}) //
{
return (*this)(begin(rng1),
end(rng1),
begin(rng2),
end(rng2),
std::move(pred),
std::move(proj));
}
RANGES_FUNC_END(find_end)
namespace cpp20
{
using ranges::find_end;
}
/// @}
} // namespace ranges
#include <range/v3/detail/epilogue.hpp>
#endif
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