74 lines
2.4 KiB
C++
74 lines
2.4 KiB
C++
/**
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This file is a part of rexy's general purpose library
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Copyright (C) 2022 rexy712
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef REXY_CONCEPTS_STRING_HPP
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#define REXY_CONCEPTS_STRING_HPP
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#include <type_traits> //decay
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#include <concepts> //convertible_to
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#include <utility> //as_const
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#include "../traits.hpp"
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namespace rexy{
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template<class Left, class Right>
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class string_cat_expr;
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template<class T>
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concept BasicString = requires(const T& a){
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{std::as_const(a).length()} -> std::convertible_to<typename std::decay_t<T>::size_type>;
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{std::as_const(a).c_str()} -> std::convertible_to<typename std::decay_t<T>::const_pointer>;
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{std::as_const(a)[0]} -> std::convertible_to<typename std::decay_t<T>::const_reference>;
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{std::as_const(a).begin()} -> std::convertible_to<typename std::decay_t<T>::const_iterator>;
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{std::as_const(a).end()} -> std::convertible_to<typename std::decay_t<T>::const_iterator>;
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};
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template<class T>
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concept StringExpr = rexy::is_template_type<T,string_cat_expr>::value;
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template<class T>
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concept String = BasicString<T> || StringExpr<T>;
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template<class T>
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struct is_string{
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static constexpr bool value = BasicString<T>;
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};
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template<class T>
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static constexpr bool is_string_v = is_string<T>::value;
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template<class... Ts>
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struct are_strings{
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static constexpr bool value = (BasicString<Ts> && ...);
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};
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template<class... Ts>
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static constexpr bool are_strings_v = are_strings<Ts...>::value;
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template<class T>
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struct is_string_expr{
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static constexpr bool value = StringExpr<T>;
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};
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template<class T>
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static constexpr bool is_string_expr_v = is_string_expr<T>::value;
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template<class... Ts>
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struct are_string_expr{
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static constexpr bool value = (StringExpr<Ts> && ...);
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};
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template<class... Ts>
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static constexpr bool are_string_expr_v = are_string_expr<Ts...>::value;
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}
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#endif
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