Module: Chess::BoardFromFenCode

Included in:
Board
Defined in:
lib/chess/board/board_from_fen.rb

Overview

create board from fen_code

Instance Method Summary collapse

Instance Method Details

#black_piece(letter) ⇒ Object

create black color piece from the letter

Parameters:

  • letter (String)

Returns:



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# File 'lib/chess/board/board_from_fen.rb', line 118

def black_piece(letter) # rubocop:disable Metrics/MethodLength
  color = 'black'
  case letter
  when 'r'
    Chess::Pieces::Rook.new(color)
  when 'n'
    Chess::Pieces::Knight.new(color)
  when 'b'
    Chess::Pieces::Bishop.new(color)
  when 'q'
    Chess::Pieces::Queen.new(color)
  when 'k'
    @black_king = Chess::Pieces::King.new(color)
  when 'p'
    Chess::Pieces::Pawn.new(color)
  end
end

#create_board(board_data) ⇒ Hash

creates board data

Parameters:

  • board_data (String) —

    board_data part of FEN code

Returns:

  • (Hash) —

    board data



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# File 'lib/chess/board/board_from_fen.rb', line 25

def create_board(board_data)
  ranks = board_data.split('/')
  files = ('a'..'h') # value for 'a' to 'h'
  board = files.to_h { |file| [file, Array.new(8) { '' }] } # empty board

  board = fill_board(ranks, board)
  @data = board
end

#create_piece(letter) ⇒ Object

create piece from the letter

Parameters:

  • letter (String)

Returns:



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# File 'lib/chess/board/board_from_fen.rb', line 83

def create_piece(letter)
  if letter == letter.upcase
    piece = white_piece(letter)
    @white_pieces << piece
  else
    piece = black_piece(letter)
    @black_pieces << piece
  end
  piece
end

#fill_board(ranks, board) ⇒ Hash

fills board with rank wise data.

Parameters:

  • ranks (Array)
  • board (Hash)

Returns:

  • (Hash) —

    filled board.



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# File 'lib/chess/board/board_from_fen.rb', line 38

def fill_board(ranks, board)
  ranks.reverse!
  ranks.each_index do |ranks_array_index|
    rank = ranks[ranks_array_index].chars
    fill_rank(board, rank, ranks_array_index)
  end
  board
end

#fill_rank(board, rank, ranks_array_index) ⇒ void

This method returns an undefined value.

fills a rank

Parameters:

  • board (Hash)
  • rank (Array)
  • ranks_array_index (Integer) 


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# File 'lib/chess/board/board_from_fen.rb', line 52

def fill_rank(board, rank, ranks_array_index)
  index = 0
  rank.each do |letter|
    if letter.to_i.zero?
      index += 1
      insert_piece(board, index, ranks_array_index, letter)
    else
      index += letter.to_i
    end
  end
end

#generate_data(fen_code) ⇒ Hash

generate game’s data from FEN code.

Parameters:

  • fen_code (String)

Returns:

  • (Hash) —

    generated_board_data



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# File 'lib/chess/board/board_from_fen.rb', line 10

def generate_data(fen_code)
  fen_parts_array = fen_code.split
  board_data = fen_parts_array[0]
  @current_player = fen_parts_array[1]
  @castling_rights = fen_parts_array[2]
  @possible_en_passant_target = fen_parts_array[3]
  @half_move = fen_parts_array[4].to_i
  @full_move = fen_parts_array[5].to_i

  create_board(board_data)
end

#insert_piece(board, index, ranks_array_index, letter) ⇒ void

This method returns an undefined value.

insert a piece on given board

Parameters:

  • board (Hash)
  • index (Integer)
  • ranks_array_index (Integer)
  • letter (String) 


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# File 'lib/chess/board/board_from_fen.rb', line 70

def insert_piece(board, index, ranks_array_index, letter)
  shift_ord = 96
  file = (shift_ord + index).chr
  rank = ranks_array_index

  board[file][rank] = create_piece(letter)
  piece_pos = [file, rank]
  board[file][rank].pos = piece_pos
end

#white_piece(letter) ⇒ Object

create white color piece from the letter

Parameters:

  • letter (String)

Returns:



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# File 'lib/chess/board/board_from_fen.rb', line 97

def white_piece(letter) # rubocop:disable Metrics/MethodLength
  color = 'white'
  case letter
  when 'R'
    Chess::Pieces::Rook.new(color)
  when 'N'
    Chess::Pieces::Knight.new(color)
  when 'B'
    Chess::Pieces::Bishop.new(color)
  when 'Q'
    Chess::Pieces::Queen.new(color)
  when 'K'
    @white_king = Chess::Pieces::King.new(color)
  when 'P'
    Chess::Pieces::Pawn.new(color)
  end
end