Class: Pawn

Inherits:
Piece show all
Defined in:
lib/bangkok/piece.rb

Instance Attribute Summary collapse

Attributes inherited from Piece

#color, #piece, #square

Instance Method Summary collapse

Methods inherited from Piece

#clear_to?, create, #move_off_board, #to_s

Constructor Details

#initialize(board, listener, color, square) ⇒ Pawn

Returns a new instance of Pawn.



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# File 'lib/bangkok/piece.rb', line 170

def initialize(board, listener, color, square)
  super(board, listener, color, :P, square)
  @moved = false
end

Instance Attribute Details

#moved ⇒ Object (readonly)

Returns the value of attribute moved.



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# File 'lib/bangkok/piece.rb', line 168

def moved
  @moved
end

Instance Method Details

#could_perform_move(move) ⇒ Object 



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# File 'lib/bangkok/piece.rb', line 180

def could_perform_move(move)
  return false unless super

  square = move.square
  if @color == :white
    if square.file == @square.file && square.rank == @square.rank + 1
      # single step forwards
      return @board.empty_at?(square)
    elsif square.file + 1 == @square.file && square.rank == @square.rank + 1
      # take a piece queenside
      return !@board.empty_at?(square)
    elsif square.file == @square.file + 1 && square.rank == @square.rank + 1
      # take a piece kingside
      return !@board.empty_at?(square)
    elsif !@moved && square.file == @square.file &&
                     square.rank == @square.rank + 2
      # first move: 2 squares forward
      return @board.empty_at?(Square.at(@square.file, @square.rank + 1)) &&
        @board.empty_at?(square)

# TODO Implement en passant checking. The following code was wrong. 

#       elsif !@moved && square.file + 1 == @square.file &&
#                        square.rank == @square.rank + 2
#         # e.p. queenside
#         return [email protected]_at?(square)
#       elsif !@moved && square.file == @square.file + 1 &&
#                        square.rank == @square.rank + 2
#         # e.p. kingside
#         return [email protected]_at?(square)

    end
  else
    # black
    if square.file == @square.file && square.rank == @square.rank - 1
      # single step forwards
      return @board.empty_at?(square)
    elsif square.file + 1 == @square.file && square.rank == @square.rank - 1
      # take a piece queenside
      return !@board.empty_at?(square)
    elsif square.file == @square.file + 1 && square.rank == @square.rank - 1
      # take a piece kingside
      return !@board.empty_at?(square)
    elsif !@moved && square.file == @square.file &&
                     square.rank == @square.rank - 2
      # first move: 2 spaces forward
      return @board.empty_at?(Square.at(@square.file, @square.rank - 1)) &&
        @board.empty_at?(square)

# TODO Implement en passant checking. The following code was wrong. 

#       elsif !@moved && square.file + 1 == @square.file &&
#                        square.rank == @square.rank - 2
#         # en passant queenside
#         return [email protected]_at?(square)
#       elsif !@moved && square.file == @square.file + 1 &&
#                        square.rank == @square.rank - 2
#         # en passant kingside
#         return [email protected]_at?(square)

    end
  end
end

#move_to(square) ⇒ Object 



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# File 'lib/bangkok/piece.rb', line 175

def move_to(square)
  @moved = true
  return super
end