PieceTypes.hpp

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/*
 * ======================================================================================
 *
 * ░▒▓███████▓▒░░▒▓████████▓▒░▒▓███████▓▒░       ░▒▓███████▓▒░ ░▒▓██████▓▒░▒▓████████▓▒░
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 * ░▒▓█▓▒░░▒▓█▓▒░▒▓█▓▒░      ░▒▓█▓▒░░▒▓█▓▒░      ░▒▓█▓▒░░▒▓█▓▒░▒▓█▓▒░░▒▓█▓▒░ ░▒▓█▓▒░
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 *
 * ======================================================================================
 */


 
#pragma once
 
#include <cstddef> // IWYU pragma: keep - for size_t
#include <cstdint> // IWYU pragma: keep - for std::uint_fast8_t
#include <expected>
#include <format>
#include <string>
#include <string_view>
#include <utility>

namespace chess::pieces {
 
using std::size_t;

enum class Type : std::uint_fast8_t {
    Pawn,   
    Knight, 
    Bishop, 
    Rook,   
    Queen,  
    King    
};

[[nodiscard]] auto from_string(std::string_view text)
    -> std::expected<Type, std::string>;

[[nodiscard, gnu::const]] constexpr auto to_char(
    Type type, bool uppercase = true)
    -> char;
 
} // namespace chess::pieces

template <>
struct std::formatter<chess::pieces::Type> final {
    template <typename ParseContext>
    constexpr auto parse(ParseContext& ctx) -> typename ParseContext::iterator
    {
        return ctx.begin();
    }
 
    template <typename FormatContext>
    auto format(
        chess::pieces::Type piece, FormatContext& ctx) const
        -> typename FormatContext::iterator
    {
        return std::format_to(ctx.out(), "{}", to_char(piece));
    }
};
 
/*
                         ___                           ,--,
      ,---,            ,--.'|_                ,--,   ,--.'|
    ,---.'|            |  | :,'             ,--.'|   |  | :
    |   | :            :  : ' :             |  |,    :  : '    .--.--.
    |   | |   ,---.  .;__,'  /    ,--.--.   `--'_    |  ' |   /  /    '
  ,--.__| |  /     \ |  |   |    /       \  ,' ,'|   '  | |  |  :  /`./
 /   ,'   | /    /  |:__,'| :   .--.  .-. | '  | |   |  | :  |  :  ;_
.   '  /  |.    ' / |  '  : |__  \__\/: . . |  | :   '  : |__ \  \    `.
'   ; |:  |'   ;   /|  |  | '.'| ," .--.; | '  : |__ |  | '.'| `----.   \
|   | '/  ''   |  / |  ;  :    ;/  /  ,.  | |  | '.'|;  :    ;/  /`--'  /__  ___  ___
|   :    :||   :    |  |  ,   /;  :   .'   \;  :    ;|  ,   /'--'.     /  .\/  .\/  .\
 \   \  /   \   \  /    ---`-' |  ,     .-./|  ,   /  ---`-'   `--'---'\  ; \  ; \  ; |
  `----'     `----'             `--`---'     ---`-'                     `--" `--" `--"
 
 */
 
namespace chess::pieces {
 
constexpr auto to_char(const Type type, const bool uppercase) -> char
{
    if (uppercase) {
        static constexpr std::string_view upperChars { "PNBRQK" };
 
        return upperChars.at(std::to_underlying(type));
    }
 
    static constexpr std::string_view lowerChars { "pnbrqk" };
 
    return lowerChars.at(std::to_underlying(type));
}
 
inline auto from_string(std::string_view text)
    -> std::expected<Type, std::string>
{
    if (text.length() != 1uz)
        text = text.substr(0uz, 1uz);
 
    switch (text.front()) {
        case 'p': [[fallthrough]];
        case 'P': return Type::Pawn;
 
        case 'n': [[fallthrough]];
        case 'N': return Type::Knight;
 
        case 'b': [[fallthrough]];
        case 'B': return Type::Bishop;
 
        case 'r': [[fallthrough]];
        case 'R': return Type::Rook;
 
        case 'q': [[fallthrough]];
        case 'Q': return Type::Queen;
 
        case 'k': [[fallthrough]];
        case 'K': return Type::King;
 
        default:
            return std::unexpected {
                std::format(
                    "Cannot parse piece type from invalid input string: {}",
                    text)
            };
    }
}
 
} // namespace chess::pieces