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Sprout/sprout/string/shrink.hpp
2015-01-10 19:13:57 +09:00

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C++

/*=============================================================================
Copyright (c) 2011-2015 Bolero MURAKAMI
https://github.com/bolero-MURAKAMI/Sprout
Distributed under 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)
=============================================================================*/
#ifndef SPROUT_STRING_SHRINK_HPP
#define SPROUT_STRING_SHRINK_HPP
#include <sprout/config.hpp>
#include <sprout/workaround/std/cstddef.hpp>
#include <sprout/index_tuple/metafunction.hpp>
#include <sprout/string/char_traits.hpp>
#include <sprout/string/string.hpp>
#include <sprout/utility/value_holder/value_holder.hpp>
#include HDR_ALGORITHM_MIN_MAX_SSCRISK_CEL_OR_SPROUT
namespace sprout {
//
// shrink_string
//
template<typename T, std::size_t N, typename Traits = sprout::char_traits<T> >
class shrink_string {
public:
typedef sprout::basic_string<T, N, Traits> string_type;
private:
typedef sprout::value_holder<string_type const&> holder_type;
private:
template<sprout::index_t... Indexes>
static SPROUT_CONSTEXPR sprout::basic_string<T, sizeof...(Indexes), Traits>
implicit_conversion_impl(
string_type const& str, std::size_t len,
sprout::index_tuple<Indexes...>
)
{
typedef sprout::detail::string_construct_access<T, sizeof...(Indexes), Traits> access_type;
return access_type::raw_construct(len, (Indexes < N ? str[Indexes] : T())...);
}
private:
holder_type holder_;
public:
shrink_string(shrink_string const&) = default;
shrink_string(shrink_string&&) = default;
SPROUT_CONSTEXPR shrink_string(string_type const& s)
: holder_(s)
{}
SPROUT_CONSTEXPR operator string_type const&() const {
return holder_.get();
}
template<std::size_t N2>
SPROUT_CONSTEXPR operator sprout::basic_string<T, N2, Traits>() const {
return implicit_conversion_impl(
holder_.get(),
NS_SSCRISK_CEL_OR_SPROUT::min(N2, holder_.get().size()),
sprout::make_index_tuple<(N < N2 ? N : N2)>::make()
);
}
};
//
// shrink
//
template<typename T, std::size_t N, typename Traits>
inline SPROUT_CONSTEXPR sprout::shrink_string<T, N, Traits>
shrink(sprout::basic_string<T, N, Traits> const& s) {
return sprout::shrink_string<T, N, Traits>(s);
}
template<std::size_t To, typename T, std::size_t N, typename Traits>
inline SPROUT_CONSTEXPR sprout::basic_string<T, To, Traits>
shrink(sprout::basic_string<T, N, Traits> const& s) {
return sprout::shrink(s);
}
template<typename T, std::size_t N>
inline SPROUT_CONSTEXPR sprout::shrink_string<T, N>
shrink(T const(& arr)[N]) {
return sprout::shrink(sprout::to_string(arr));
}
template<std::size_t To, typename T, std::size_t N>
inline SPROUT_CONSTEXPR sprout::basic_string<T, To>
shrink(T const(& arr)[N]) {
return sprout::shrink<To>(sprout::to_string(arr));
}
} // namespace sprout
#endif // #ifndef SPROUT_STRING_SHRINK_HPP