char.hpp

/*
 * Copyright (c) 2024 The RefValue Project
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 * of this software and associated documentation files (the "Software"), to deal
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 * furnished to do so, subject to the following conditions:
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 * The above copyright notice and this permission notice shall be included in
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 *
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 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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 * THE SOFTWARE.
 */
 
#pragma once
 
#include <concepts>
#include <cstddef>
#include <type_traits>
 
namespace essence {
    template <typename T>
    concept builtin_char_type =
        std::same_as<T, char> || std::same_as<T, char8_t> || std::same_as<T, char16_t> || std::same_as<T, char32_t>
        || std::same_as<T, signed char> || std::same_as<T, unsigned char>;
 
    template <typename T>
    concept byte_like = std::same_as<std::decay_t<T>, char> || std::same_as<std::decay_t<T>, unsigned char>
                     || std::same_as<std::decay_t<T>, signed char> || std::same_as<std::decay_t<T>, std::byte>;
 
    template <builtin_char_type T>
    constexpr bool is_lower(T c) noexcept {
        return c >= T{'a'} && c <= T{'z'};
    }
 
    template <builtin_char_type T>
    constexpr bool is_upper(T c) noexcept {
        return c >= T{'A'} && c <= T{'Z'};
    }
 
    template <builtin_char_type T>
    constexpr T to_lower(T c) noexcept {
        return is_upper(c) ? static_cast<T>(c - T{'A'} + T{'a'}) : c;
    }
 
    template <builtin_char_type T>
    constexpr T to_upper(T c) noexcept {
        return is_lower(c) ? static_cast<T>(c - T{'a'} + T{'A'}) : c;
    }
} // namespace essence