Die Board-Klasse zur Repräsentation des Schachbretts

Die Board-Klasse bildet das Herzstück des Schachprojekts. Sie stellt eine flexible und erweiterbare Datenstruktur dar, mit der sich Schachstellungen speichern, verändern, bewerten und analysieren lassen. Die Klasse ist in zwei Ebenen aufgebaut: eine abstrakte Basisklasse (BoardBase) mit grundlegender Funktionalität und eine erweiterte Implementierung (Board), in der zentrale Methoden von den Studierenden selbst implementiert werden.

Ziel ist es, ein realistisch spielbares Schachbrett in Python zu modellieren, das als Grundlage für weiterführende KI-Algorithmen wie Mini-Max dient. Dabei übernimmt die Board-Klasse nicht nur das Verwalten der Figurenpositionen, sondern bietet auch Methoden zur Bewertung der Stellung, zur Validierung von Zügen sowie zur Erkennung kritischer Spielsituationen wie Schach.

Funktionalität im Überblick

Die Klasse erlaubt unter anderem folgende Operationen:

• Initialisierung und Zurücksetzen eines vollständigen Startbretts (reset)

• Einfügen, Entfernen und Überprüfen von Figuren auf bestimmten Feldern (set_cell, get_cell)

• Serialisierung der Stellung zur Anzeige oder Speicherung (__str__, hash, save_to_disk, load_from_disk)

• Bewertung der aktuellen Stellung aus Sicht von Weiß (evaluate)

• Erkennung von Schach-Situationen mittels gegnerischer Angriffsreichweiten (is_king_check)

• Zugvalidierung, etwa ob ein Feld betreten oder angegriffen werden darf (piece_can_enter_cell, piece_can_hit_on_cell)

• Iteration über Spielfiguren nach Farbe (iterate_cells_with_pieces)

• Laden von Stellungen aus Strings (z. B. für Spielwiederherstellung oder Tests)

Modularer Aufbau und Erweiterbarkeit

Die Klasse wurde so entworfen, dass sie sowohl als eigenständiges Brettmodell als auch als Baustein für Schach-KI-Algorithmen dient. Insbesondere ermöglicht sie es, die Spiellogik klar von der Bewertungslogik und der KI-Strategie zu trennen. Dadurch können später Suchalgorithmen wie Mini-Max oder Alpha-Beta-Pruning problemlos auf dieser Basis aufbauen.

Die Board-Klasse dient somit als zentrales Bindeglied zwischen Spiellogik, Benutzeroberfläche und KI – und ist damit ein essenzieller Bestandteil eures Schachcomputers.

Reference - Board

class board.Board

Your implementation of the chess board. You will need to find implementations for all of these methods.

HINT: Read the documentation carefully. Also look at the parent class (BoardBase) for further reference and example implementations.

cell_is_valid_and_empty(cell)

TODO: Check if the given cell is empty, meaning there is no piece placed on it.

HINT: You can use the “is_valid_cell()” Method to verify the cell is valid in the first place. If so, use “get_cell()” to retrieve the piece placed on it and return True if there is None

evaluate()

TODO: Evaluate the current board configuration into a numerical number. The higher the number, to more favorable for WHITE (note: This is always from whites perspective!) the current configuration is.

HINT: Start with a score of zero. Use the iterate_cells_with_pieces Method to find all WHITE pieces and call their respective “evaluate” Method. Sum those scores up. Then use the iterate_cells_with_pieces Method to find all BLACK pieces, call their respective “evaluate” Method and substract that from the score.

find_king(white)

TODO: Find the king piece of given color and return that piece

HINT: You can use the iterate_cells_with_pieces() Method to find all pieces of a given color

Parameters:

white (Boolean) – True if WHITE pieces are to be iterated, False otherwise

Returns:

The :py:class:’King’: object of the given color or None if there is no King on the board.

is_king_check(white)

TODO: Evaluate if the king of given color is currently in check. A check is given if any opposing piece can beat the king in its next move.

HINT: You can use the find_king() Method to find the king of the given color. Then use the iterate_cells_with_pieces Method to find all pieces of opposing color (negate the “white”-parameter) For each opposing piece, call the “get_reachable_cells()” method to get a list of all reachable cells. Iterate over each reachable cell and check if the kings cell is reachable. If yes, shortcut and return True right away.

is_valid_cell(cell)

TODO: Check if the given cell coordinates are valid. A cell coordinate is valid if both row and coloumn are between 0 and 7 inclusively.

HINT: Cell is a tuple (row, col) of row and column. Unpack the tuple and check both row and col for being within the allowed range (0 to 7 inclusively). Don´t forget to handle the special case of “cell” being None. Return False in that case

iterate_cells_with_pieces(white)

TODO: Write a generator (using the yield keyword) that allows to iterate over all cells with a piece of given color.

HINT: You need a double-nested loop, the first one iterates over all the rows, the second one iterates over each cell in the current row. If the cell has a piece (so it is not None) and the piece has the correct color, yield it

Parameters:

white (Boolean) – True if WHITE pieces are to be iterated, False otherwise

piece_can_enter_cell(piece, cell)

TODO: Check if the given piece can enter the given cell. Note: You don´t need to check movement rules for the individual piece here. You only need to answer the question whether the piece can be placed on the given cell or not.

A piece can be placed on a cell if the cell is valid and either empty or an opposing piece is placed here. A cell cannot be entered if a piece of the same color is already in that cell.

HINT: You can use the “is_valid_cell()” Method to verify the cell is valid in the first place. If so, use “get_cell()” to retrieve the piece placed on it. If there is None, this cell can be entered If, however, there is another piece, it must be of opposing color. Check the other pieces “white” attribute and compare against the given piece “white” attribute.

piece_can_hit_on_cell(piece, cell)

TODO: Check if the given piece can hit at the given cell. Note: You don´t need to check movement rules for the individual piece here. You only need to answer the question whether the piece can be placed on the given cell or not and hit an opposing piece.

A piece can hit on a cell if the cell is valid and an opposing piece is placed here. A cell cannot be hit if the cell is empty or a piece of the same color is already in that cell.

HINT: You can use the “is_valid_cell()” Method to verify the cell is valid in the first place. If so, use “get_cell()” to retrieve the piece placed on it. If there is None, this cell cannot be hit. If, however, there is another piece, it must be of opposing color. Check the other pieces “white” attribute and compare against the given piece “white” attribute.

Reference - Base Board

class board.BoardBase

Base Class for the Chess Board. You are free to look around the members of this class and their implementation, however you will not need to change anything in this class for any of the tasks.

clear_board()

Clears to board, deleting all pieces currently placed on it

get_cell(cell)

Retrieves the piece placed on the given cell or “None” if cell is invalid

hash()

Returns a unique hash (string) representation for the current board configuration. This is short form, not meant for readability.

is_king_check_cached(white)

Calls is_king_check for board configurations not yet known. Caches the result for later look-up.

load_from_disk(fname)

Read previously stored configuration from disk

Parameters:

name – Filename to use.

load_from_memory(configString)

Read previously stored configuration from a memory string

Parameters:

name – Filename to use.

reset()

Resets the board to its default (start) configuration

save_to_disk(fname=None)

Saves current board configuration to disk.

Parameters:

name – Filename to use. If None is provided, a unique one will be generated

set_cell(cell, piece)

Places a piece on a given cell.