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https://github.com/bolero-MURAKAMI/Sprout.git
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63 lines
1.9 KiB
C++
63 lines
1.9 KiB
C++
#ifndef SPROUT_STRING_SHRINK_HPP
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#define SPROUT_STRING_SHRINK_HPP
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#include <cstddef>
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#include <sprout/config.hpp>
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#include <sprout/index_tuple.hpp>
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#include <sprout/string/char_traits.hpp>
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#include <sprout/string/string.hpp>
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#include <sprout/utility/value_holder.hpp>
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#include HDR_ALGORITHM_SSCRISK_CEL_OR_SPROUT
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namespace sprout {
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//
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// shrink_string
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//
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template<typename T, std::size_t N, typename Traits = sprout::char_traits<T> >
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class shrink_string {
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public:
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typedef sprout::basic_string<T, N, Traits> string_type;
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private:
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typedef sprout::value_holder<string_type const&> holder_type;
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private:
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template<std::size_t M, sprout::index_t... Indexes>
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static SPROUT_CONSTEXPR sprout::basic_string<T, sizeof...(Indexes), Traits> implicit_conversion_impl(
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T const(& elems)[M],
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std::size_t len,
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sprout::index_tuple<Indexes...>
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)
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{
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return sprout::basic_string<T, sizeof...(Indexes), Traits>{{(Indexes < M - 1 ? elems[Indexes] : T())...}, len};
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}
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private:
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holder_type holder_;
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public:
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shrink_string(shrink_string const&) = default;
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shrink_string(shrink_string&&) = default;
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SPROUT_CONSTEXPR shrink_string(string_type const& s)
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: holder_(s)
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{}
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SPROUT_CONSTEXPR operator string_type const&() const {
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return holder_.get();
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}
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template<std::size_t N2>
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SPROUT_CONSTEXPR operator sprout::basic_string<T, N2, Traits>() const {
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return implicit_conversion_impl(
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holder_.get().elems,
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NS_SSCRISK_CEL_OR_SPROUT::min(N2, holder_.get().len),
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sprout::index_range<0, NS_SSCRISK_CEL_OR_SPROUT::min(N2, N)>::make()
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);
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}
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};
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//
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// shrink
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//
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template<typename T, std::size_t N, typename Traits>
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SPROUT_CONSTEXPR sprout::shrink_string<T, N, Traits>
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shrink(sprout::basic_string<T, N, Traits> const& s) {
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return sprout::shrink_string<T, N, Traits>(s);
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}
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} // namespace sprout
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#endif // #ifndef SPROUT_STRING_SHRINK_HPP
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