Module: Pawn

Extended by:
Pawn
Included in:
BlackPawn, Pawn, WhitePawn
Defined in:
lib/pawn.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Instance Attribute Details

#direction ⇒ Object (readonly)

Returns the value of attribute direction.



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# File 'lib/pawn.rb', line 5

def direction
  @direction
end

Instance Method Details

#illegal(board, x, y) ⇒ Object

Raises:



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# File 'lib/pawn.rb', line 33

def illegal(board,x,y)
  possible_moves = [
    [@x, @y+(1 * @direction)],
  ]
  possible_moves << [@x, @y+(2 * @direction)] if @start
  possible_moves = Board.board_safe(possible_moves)

  possible_attack_moves = Board.board_safe([
    [@x-1, @y+(1 * @direction)],
    [@x+1, @y+(1 * @direction)] 
  ])

  en_passent = board.en_passent
  en_passent_coord = en_passent.to_coord
  en_passent_coord[1] &&= en_passent_coord[1] - en_passent.direction

  if board.at(x,y).friend_of?(self)
    error = "Your piece is blocking your path"
  elsif board.at(x,y).enemy_of?(self)
    unless possible_attack_moves.find {|move| move == [x,y]}
      error = "Cannot move this way!"
    end
  elsif en_passent_coord == [x,y] 
    unless possible_attack_moves.find {|move| move == [x,y]}
      error = "Cannot move this way!"
    else
      en_passent.remove_from(board)
    end
  else
    unless possible_moves.find {|move| move == [x,y]}
      error = "Cannot move here!"
    else
      if jumped?(board,x,y)
        raise Game::IllegalMove, "Pawns cannot jump!" 
      end
    end
  end

  raise Game::IllegalMove, error if error 
end

#jumped?(board, x, y) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/pawn.rb', line 74

def jumped?(board,x,y)
  return false unless (@y-y).abs == 2
  !board.at(x,y-@direction).empty?
end

#move(board, x, y) ⇒ Object

attempt to move the piece to x,y on the board



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# File 'lib/pawn.rb', line 8

def move(board,x,y)
  # check if it is an illegal move (raises Game::IllegalMove if it is)
  illegal(board, x, y)

  # make start false if it not already false
  !@start || @start = false

  # remove the piece from it's original position 
  board.remove(self)
  
  # save the piece if it can be taken by en passent
  board.en_passent = (@y-y).abs == 2 ? self : NullSpace.new 

  # update the coordinates
  @x, @y = x, y

  # replace with queen if on back row
  if @y == Board::BackRow[color]  
    board.place(@queen.new(@x,@y))
  else
    # or place on board
    place_on(board)
  end
end