BenBot 1.7.5
A chess engine
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chess::game::Square Struct Referencefinal

#include <libchess/board/Square.hpp>

Public Member Functions

constexpr auto index () const noexcept -> BitboardIndex
constexpr auto is_dark () const noexcept -> bool
constexpr auto is_light () const noexcept -> bool
constexpr auto operator== (const Square &) const noexcept -> bool=default
Area queries
constexpr auto is_queenside () const noexcept -> bool
constexpr auto is_kingside () const noexcept -> bool
constexpr auto is_white_territory () const noexcept -> bool
constexpr auto is_black_territory () const noexcept -> bool

Static Public Member Functions

static constexpr auto from_index (BitboardIndex index) noexcept -> Square
static auto from_string (std::string_view text) -> std::expected< Square, std::string >

Public Attributes

File file { File::A }
Rank rank { Rank::One }

(Note that these are not member symbols.)

constexpr auto file_distance (const Square &first, const Square &second) noexcept -> BitboardIndex
constexpr auto rank_distance (const Square &first, const Square &second) noexcept -> BitboardIndex
constexpr auto are_on_same_diagonal (const Square &first, const Square &second) noexcept -> bool
constexpr auto manhattan_distance (const Square &first, const Square &second) noexcept -> BitboardIndex
constexpr auto center_manhattan_distance (const Square &square) noexcept -> BitboardIndex
constexpr auto chebyshev_distance (const Square &first, const Square &second) noexcept -> BitboardIndex
auto knight_distance (const Square &first, const Square &second) -> BitboardIndex
constexpr auto operator<=> (const Square &first, const Square &second) noexcept -> std::strong_ordering

Detailed Description

This struct uniquely identifies a square on the chessboard via its rank and file, and provides mappings to and from bitboard indices.

This class uses the "Least Significant File" mapping to calculate bitboard indices, as opposed to the "Least Significant Rank" mapping. This means that ranks are aligned to the eight consecutive bytes of a bitboard.

This results in the following mapping of squares to bitboard indices:

Rank A B C D E F G H
8 56 57 58 59 60 61 62 63
7 48 49 50 51 52 53 54 55
6 40 41 42 43 44 45 46 47
5 32 33 34 35 36 37 38 39
4 24 25 26 27 28 29 30 31
3 16 17 18 19 20 21 22 23
2 8 9 10 11 12 13 14 15
1 0 1 2 3 4 5 6 7

Definition at line 72 of file Square.hpp.

Member Function Documentation

◆ from_index()

auto chess::board::Square::from_index ( BitboardIndex index) -> Square
staticnodiscardconstexprnoexcept

Calculates the rank and file corresponding to the given bitboard index. This function asserts if the passed index is greater than 63.

Definition at line 191 of file Square.hpp.

◆ from_string()

auto chess::board::Square::from_string ( std::string_view text) -> std::expected< Square, std::string >
inlinestaticnodiscard

Creates a square from a string in algebraic notation, such as "A1", "H4", etc.

This method recognizes either upper- or lower-case file letters.

If the input string cannot be parsed correctly, returns an explanatory error string.

Definition at line 237 of file Square.hpp.

◆ index()

auto chess::board::Square::index ( ) const -> BitboardIndex
nodiscardconstexprnoexcept

Returns the bitboard bit index for this square. The returned index will be in the range [0,63].

Definition at line 201 of file Square.hpp.

◆ is_black_territory()

auto chess::board::Square::is_black_territory ( ) const -> bool
nodiscardconstexprnoexcept

Returns true if this square is within Black's territory (the fifth through eighth ranks).

Definition at line 225 of file Square.hpp.

◆ is_dark()

auto chess::board::Square::is_dark ( ) const -> bool
inlinenodiscardconstexprnoexcept

Returns true if this is a dark square.

Definition at line 121 of file Square.hpp.

◆ is_kingside()

auto chess::board::Square::is_kingside ( ) const -> bool
nodiscardconstexprnoexcept

Returns true if this square is on the kingside (the E-H files).

Definition at line 213 of file Square.hpp.

◆ is_light()

auto chess::board::Square::is_light ( ) const -> bool
nodiscardconstexprnoexcept

Returns true if this is a light square.

Definition at line 231 of file Square.hpp.

◆ is_queenside()

auto chess::board::Square::is_queenside ( ) const -> bool
nodiscardconstexprnoexcept

Returns true if this square is on the queenside (the A-D files).

Definition at line 207 of file Square.hpp.

◆ is_white_territory()

auto chess::board::Square::is_white_territory ( ) const -> bool
nodiscardconstexprnoexcept

Returns true if this square is within White's territory (the first through fourth ranks).

Definition at line 219 of file Square.hpp.

◆ operator==()

auto chess::board::Square::operator== ( const Square & ) const -> bool=default
nodiscardconstexprdefaultnoexcept

Returns true if two squares are equivalent.

Member Data Documentation

◆ file

File chess::board::Square::file { File::A }

This square's file.

Definition at line 74 of file Square.hpp.

◆ rank

Rank chess::board::Square::rank { Rank::One }

This square's rank.

Definition at line 77 of file Square.hpp.

The documentation for this struct was generated from the following files: