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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
//
//===----------------------------------------------------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is dual licensed under the MIT and the University of Illinois Open
// Source Licenses. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#ifndef RANGES_V3_ALGORITHM_SEARCH_N_HPP
#define RANGES_V3_ALGORITHM_SEARCH_N_HPP
#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/primitives.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
{
/// \addtogroup group-algorithms
/// @{
/// \cond
namespace detail
{
template<typename I, typename S, typename D, typename V, typename C, typename P>
constexpr subrange<I> search_n_sized_impl(I const begin_,
S last,
D const d_,
D cnt,
V const & val,
C & pred,
P & proj)
{
D d = d_; // always the distance from first to end
auto first = uncounted(begin_);
while(true)
{
// Find first element in sequence 1 that matches val, with a mininum of
// loop checks
while(true)
{
if(d < cnt) // return the last if we've run out of room
{
auto e = ranges::next(recounted(begin_, std::move(first), d_ - d),
std::move(last));
return {e, e};
}
if(invoke(pred, invoke(proj, *first), val))
break;
++first;
--d;
}
// *first matches val, now match elements after here
auto m = first;
D c = 0;
while(true)
{
if(++c == cnt) // If pattern exhausted, first is the answer (works
// for 1 element pattern)
return {recounted(begin_, std::move(first), d_ - d),
recounted(begin_, std::move(++m), d_ - d)};
++m; // No need to check, we know we have room to match successfully
if(!invoke(pred,
invoke(proj, *m),
val)) // if there is a mismatch, restart with a new begin
{
first = next(std::move(m));
d -= (c + 1);
break;
} // else there is a match, check next elements
}
}
}
template<typename I, typename S, typename D, typename V, typename C, typename P>
constexpr subrange<I> search_n_impl(I first,
S last,
D cnt,
V const & val,
C & pred,
P & proj)
{
while(true)
{
// Find first element in sequence 1 that matches val, with a mininum of
// loop checks
while(true)
{
if(first == last) // return last if no element matches val
return {first, first};
if(invoke(pred, invoke(proj, *first), val))
break;
++first;
}
// *first matches val, now match elements after here
I m = first;
D c = 0;
while(true)
{
if(++c == cnt) // If pattern exhausted, first is the answer (works
// for 1 element pattern)
return {first, ++m};
if(++m == last) // Otherwise if source exhausted, pattern not found
return {m, m};
if(!invoke(pred,
invoke(proj, *m),
val)) // if there is a mismatch, restart with a new begin
{
first = next(std::move(m));
break;
} // else there is a match, check next elements
}
}
}
} // namespace detail
/// \endcond
RANGES_FUNC_BEGIN(search_n)
/// \brief function template \c search_n
template(typename I,
typename S,
typename V,
typename C = equal_to,
typename P = identity)(
requires forward_iterator<I> AND sentinel_for<S, I> AND
indirectly_comparable<I, V const *, C, P>)
constexpr subrange<I> RANGES_FUNC(search_n)(I first,
S last,
iter_difference_t<I> cnt,
V const & val,
C pred = C{},
P proj = P{}) //
{
if(cnt <= 0)
return {first, first};
if(RANGES_CONSTEXPR_IF(sized_sentinel_for<S, I>))
return detail::search_n_sized_impl(std::move(first),
std::move(last),
distance(first, last),
cnt,
val,
pred,
proj);
else
return detail::search_n_impl(
std::move(first), std::move(last), cnt, val, pred, proj);
}
/// \overload
template(typename Rng, typename V, typename C = equal_to, typename P = identity)(
requires forward_range<Rng> AND
indirectly_comparable<iterator_t<Rng>, V const *, C, P>)
constexpr borrowed_subrange_t<Rng> RANGES_FUNC(search_n)(Rng && rng,
iter_difference_t<iterator_t<Rng>> cnt,
V const & val,
C pred = C{},
P proj = P{}) //
{
if(cnt <= 0)
return subrange<iterator_t<Rng>>{begin(rng), begin(rng)};
if(RANGES_CONSTEXPR_IF(sized_range<Rng>))
return detail::search_n_sized_impl(
begin(rng), end(rng), distance(rng), cnt, val, pred, proj);
else
return detail::search_n_impl(begin(rng), end(rng), cnt, val, pred, proj);
}
RANGES_FUNC_END(search_n)
namespace cpp20
{
using ranges::search_n;
}
/// @}
} // namespace ranges
#include <range/v3/detail/epilogue.hpp>
#endif
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