font_variant.hpp

// Copyright Take Vos 2020-2022.
// Distributed under the Boost Software License, Version 1.0.
// (See accompanying file LICENSE_1_0.txt or copy at https://www.boost.org/LICENSE_1_0.txt)
 
#pragma once
 
#include "font_weight.hpp"
#include "font_style.hpp"
 
namespace hi::inline v1 {

class font_variant {
public:
    [[nodiscard]] constexpr static size_t size() noexcept
    {
        return font_weight_metadata.size() * font_style_metadata.size();
    }
 
    constexpr font_variant(font_weight weight, font_style style) noexcept :
        _value(narrow_cast<uint8_t>((to_underlying(weight) << 1) | to_underlying(style)))
    {
    }
 
    constexpr font_variant() noexcept : font_variant(font_weight::regular, font_style::normal) {}
    constexpr font_variant(font_weight weight) noexcept : font_variant(weight, font_style::normal) {}
    constexpr font_variant(font_style style) noexcept : font_variant(font_weight::regular, style) {}
 
    [[nodiscard]] constexpr operator size_t() const noexcept
    {
        return to_underlying(style()) + to_underlying(weight()) * font_style_metadata.size();
    }
 
    [[nodiscard]] size_t hash() const noexcept
    {
        return std::hash<uint8_t>{}(_value);
    }
 
    constexpr font_weight weight() const noexcept
    {
        return static_cast<font_weight>(_value >> 1);
    }
 
    [[nodiscard]] constexpr font_style style() const noexcept
    {
        return static_cast<font_style>(_value & 1);
    }
 
    constexpr font_variant& set_weight(font_weight rhs) noexcept
    {
        _value &= 1;
        _value |= to_underlying(rhs) << 1;
        return *this;
    }
 
    constexpr font_variant& set_style(font_style rhs) noexcept
    {
        _value &= 0x1e;
        _value |= to_underlying(rhs);
        return *this;
    }

    [[nodiscard]] friend generator<font_variant> alternatives(font_variant const& start) noexcept
    {
        for (hilet s : alternatives(start.style())) {
            for (hilet w : alternatives(start.weight())) {
                co_yield font_variant{w, s};
            }
        }
    }
 
    [[nodiscard]] friend std::string to_string(font_variant const& rhs) noexcept
    {
        return std::format("{}", rhs.weight(), rhs.style() == font_style::italic ? "/italic" : "");
    }
 
    friend std::ostream& operator<<(std::ostream& lhs, font_variant const& rhs)
    {
        return lhs << to_string(rhs);
    }
 
private:
    uint8_t _value;
};
 
} // namespace hi::inline v1
 
template<>
struct std::hash<hi::font_variant> {
    [[nodiscard]] size_t operator()(hi::font_variant const& rhs) const noexcept
    {
        return rhs.hash();
    }
};