320 lines
11 KiB
C++
320 lines
11 KiB
C++
/*!
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@file
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Defines `boost::hana::string`.
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@copyright Louis Dionne 2013-2016
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Distributed under the Boost Software License, Version 1.0.
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(See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
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*/
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#ifndef BOOST_HANA_STRING_HPP
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#define BOOST_HANA_STRING_HPP
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#include <boost/hana/fwd/string.hpp>
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#include <boost/hana/bool.hpp>
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#include <boost/hana/config.hpp>
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#include <boost/hana/core/make.hpp>
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#include <boost/hana/detail/algorithm.hpp>
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#include <boost/hana/detail/operators/adl.hpp>
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#include <boost/hana/detail/operators/comparable.hpp>
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#include <boost/hana/detail/operators/iterable.hpp>
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#include <boost/hana/detail/operators/orderable.hpp>
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#include <boost/hana/fwd/at.hpp>
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#include <boost/hana/fwd/contains.hpp>
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#include <boost/hana/fwd/core/tag_of.hpp>
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#include <boost/hana/fwd/core/to.hpp>
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#include <boost/hana/fwd/drop_front.hpp>
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#include <boost/hana/fwd/equal.hpp>
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#include <boost/hana/fwd/find.hpp>
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#include <boost/hana/fwd/front.hpp>
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#include <boost/hana/fwd/hash.hpp>
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#include <boost/hana/fwd/is_empty.hpp>
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#include <boost/hana/fwd/length.hpp>
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#include <boost/hana/fwd/less.hpp>
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#include <boost/hana/fwd/plus.hpp>
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#include <boost/hana/fwd/unpack.hpp>
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#include <boost/hana/fwd/zero.hpp>
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#include <boost/hana/if.hpp>
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#include <boost/hana/integral_constant.hpp>
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#include <boost/hana/optional.hpp>
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#include <boost/hana/type.hpp>
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#include <utility>
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#include <cstddef>
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#include <type_traits>
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BOOST_HANA_NAMESPACE_BEGIN
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//////////////////////////////////////////////////////////////////////////
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// string<>
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//////////////////////////////////////////////////////////////////////////
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//! @cond
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namespace detail {
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template <char ...s>
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constexpr char const string_storage[sizeof...(s) + 1] = {s..., '\0'};
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}
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template <char ...s>
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struct string
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: detail::operators::adl<string<s...>>
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, detail::iterable_operators<string<s...>>
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{
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static constexpr char const* c_str() {
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return &detail::string_storage<s...>[0];
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}
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};
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//! @endcond
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template <char ...s>
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struct tag_of<string<s...>> {
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using type = string_tag;
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};
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//////////////////////////////////////////////////////////////////////////
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// make<string_tag>
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//////////////////////////////////////////////////////////////////////////
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template <>
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struct make_impl<string_tag> {
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template <typename ...Chars>
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static constexpr auto apply(Chars const& ...) {
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return hana::string<hana::value<Chars>()...>{};
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}
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};
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//////////////////////////////////////////////////////////////////////////
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// BOOST_HANA_STRING
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//////////////////////////////////////////////////////////////////////////
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namespace string_detail {
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template <typename S, std::size_t ...N>
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constexpr string<S::get()[N]...>
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prepare_impl(S, std::index_sequence<N...>)
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{ return {}; }
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template <typename S>
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constexpr decltype(auto) prepare(S s) {
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return prepare_impl(s,
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std::make_index_sequence<sizeof(S::get()) - 1>{});
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}
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}
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#define BOOST_HANA_STRING(s) \
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(::boost::hana::string_detail::prepare([]{ \
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struct tmp { \
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static constexpr decltype(auto) get() { return s; } \
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}; \
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return tmp{}; \
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}())) \
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/**/
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#ifdef BOOST_HANA_CONFIG_ENABLE_STRING_UDL
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//////////////////////////////////////////////////////////////////////////
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// _s user-defined literal
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//////////////////////////////////////////////////////////////////////////
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namespace literals {
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template <typename CharT, CharT ...s>
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constexpr auto operator"" _s() {
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static_assert(std::is_same<CharT, char>::value,
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"hana::string: Only narrow string literals are supported with "
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"the _s string literal right now. See https://goo.gl/fBbKD7 "
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"if you need support for fancier types of compile-time strings.");
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return hana::string_c<s...>;
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}
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}
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#endif
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//////////////////////////////////////////////////////////////////////////
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// Operators
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//////////////////////////////////////////////////////////////////////////
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namespace detail {
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template <>
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struct comparable_operators<string_tag> {
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static constexpr bool value = true;
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};
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template <>
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struct orderable_operators<string_tag> {
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static constexpr bool value = true;
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};
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}
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//////////////////////////////////////////////////////////////////////////
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// to<char const*>
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//////////////////////////////////////////////////////////////////////////
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template <>
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struct to_impl<char const*, string_tag> {
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template <char ...c>
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static constexpr char const* apply(string<c...> const&)
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{ return string<c...>::c_str(); }
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};
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//////////////////////////////////////////////////////////////////////////
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// Comparable
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//////////////////////////////////////////////////////////////////////////
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template <>
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struct equal_impl<string_tag, string_tag> {
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template <typename S>
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static constexpr auto apply(S const&, S const&)
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{ return hana::true_c; }
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template <typename S1, typename S2>
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static constexpr auto apply(S1 const&, S2 const&)
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{ return hana::false_c; }
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};
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//////////////////////////////////////////////////////////////////////////
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// Orderable
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//////////////////////////////////////////////////////////////////////////
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template <>
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struct less_impl<string_tag, string_tag> {
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template <char ...s1, char ...s2>
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static constexpr auto
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apply(string<s1...> const&, string<s2...> const&) {
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// We put a '\0' at the end only to avoid empty arrays.
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constexpr char const c_str1[] = {s1..., '\0'};
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constexpr char const c_str2[] = {s2..., '\0'};
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return hana::bool_c<detail::lexicographical_compare(
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c_str1, c_str1 + sizeof...(s1),
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c_str2, c_str2 + sizeof...(s2)
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)>;
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}
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};
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//////////////////////////////////////////////////////////////////////////
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// Monoid
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//////////////////////////////////////////////////////////////////////////
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template <>
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struct plus_impl<string_tag, string_tag> {
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template <char ...s1, char ...s2>
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static constexpr auto
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apply(string<s1...> const&, string<s2...> const&) {
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return string<s1..., s2...>{};
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}
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};
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template <>
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struct zero_impl<string_tag> {
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static constexpr auto apply() {
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return string<>{};
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}
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};
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template <char ...s1, char ...s2>
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constexpr auto operator+(string<s1...> const&, string<s2...> const&) {
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return hana::string<s1..., s2...>{};
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}
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//////////////////////////////////////////////////////////////////////////
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// Foldable
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//////////////////////////////////////////////////////////////////////////
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template <>
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struct unpack_impl<string_tag> {
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template <char ...s, typename F>
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static constexpr decltype(auto) apply(string<s...> const&, F&& f)
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{ return static_cast<F&&>(f)(char_<s>{}...); }
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};
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template <>
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struct length_impl<string_tag> {
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template <char ...s>
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static constexpr auto apply(string<s...> const&)
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{ return hana::size_c<sizeof...(s)>; }
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};
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//////////////////////////////////////////////////////////////////////////
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// Iterable
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//////////////////////////////////////////////////////////////////////////
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template <>
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struct front_impl<string_tag> {
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template <char x, char ...xs>
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static constexpr auto apply(string<x, xs...> const&)
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{ return hana::char_c<x>; }
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};
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template <>
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struct drop_front_impl<string_tag> {
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template <std::size_t N, char ...xs, std::size_t ...i>
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static constexpr auto helper(string<xs...> const&, std::index_sequence<i...>) {
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constexpr char s[] = {xs...};
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return hana::string_c<s[i + N]...>;
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}
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template <char ...xs, typename N>
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static constexpr auto apply(string<xs...> const& s, N const&) {
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return helper<N::value>(s, std::make_index_sequence<
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N::value < sizeof...(xs) ? sizeof...(xs) - N::value : 0
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>{});
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}
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template <typename N>
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static constexpr auto apply(string<> const& s, N const&)
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{ return s; }
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};
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template <>
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struct is_empty_impl<string_tag> {
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template <char ...s>
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static constexpr auto apply(string<s...> const&)
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{ return hana::bool_c<sizeof...(s) == 0>; }
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};
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template <>
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struct at_impl<string_tag> {
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template <char ...s, typename N>
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static constexpr auto apply(string<s...> const&, N const&) {
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// We put a '\0' at the end to avoid an empty array.
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constexpr char characters[] = {s..., '\0'};
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constexpr auto n = N::value;
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return hana::char_c<characters[n]>;
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}
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};
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//////////////////////////////////////////////////////////////////////////
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// Searchable
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//////////////////////////////////////////////////////////////////////////
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template <>
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struct contains_impl<string_tag> {
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template <char ...s, typename C>
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static constexpr auto
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helper(string<s...> const&, C const&, hana::true_) {
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constexpr char const characters[] = {s..., '\0'};
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constexpr char c = hana::value<C>();
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return hana::bool_c<
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detail::find(characters, characters + sizeof...(s), c)
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!= characters + sizeof...(s)
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>;
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}
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template <typename S, typename C>
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static constexpr auto helper(S const&, C const&, hana::false_)
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{ return hana::false_c; }
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template <typename S, typename C>
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static constexpr auto apply(S const& s, C const& c)
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{ return helper(s, c, hana::bool_c<hana::Constant<C>::value>); }
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};
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template <>
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struct find_impl<string_tag> {
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template <char ...s, typename Char>
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static constexpr auto apply(string<s...> const& str, Char const& c) {
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return hana::if_(contains_impl<string_tag>::apply(str, c),
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hana::just(c),
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hana::nothing
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);
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}
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};
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//////////////////////////////////////////////////////////////////////////
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// Hashable
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//////////////////////////////////////////////////////////////////////////
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template <>
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struct hash_impl<string_tag> {
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template <typename String>
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static constexpr auto apply(String const&) {
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return hana::type_c<String>;
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}
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};
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BOOST_HANA_NAMESPACE_END
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#endif // !BOOST_HANA_STRING_HPP
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