Class: ChessData::Moves::PieceMove

Inherits:
Object
  • Object
show all
Defined in:
lib/chess_data/moves.rb

Overview

Methods to support a piece move.

Instance Method Summary collapse

Constructor Details

#initialize(move) ⇒ PieceMove

Returns a new instance of PieceMove.



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# File 'lib/chess_data/moves.rb', line 459

def initialize move
  @move_string = move
  move =~ MatchPieceMove
  @piece = $1
  @identifier = $2
  @destination = $3
  @is_capture = move.include? "x"
end

Instance Method Details

#make_move(board) ⇒ Object

Returns a new instance of the board after move is made.



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# File 'lib/chess_data/moves.rb', line 473

def make_move board
  @piece.downcase! if board.to_move == "b"
  # for given piece type, locate those pieces on board which can reach destination
  origin = board.locations_of(@piece, @identifier).select do |loc| 
    Moves.can_reach(board, @piece, loc, @destination)
  end
  # filter out ambiguities raised by king being left in check
  if origin.length > 1
    origin = origin.delete_if do |loc|
      Moves.king_left_in_check(board, @piece, loc, @destination)
    end
  end
  # there should only be one unique piece at this point
  # raise an InvalidMoveError if not
  unless origin.length == 1 && board[origin.first] == @piece
    raise InvalidMoveError, "Not a unique/valid choice for #{@piece} to #{@destination}"
  end
  # setup a revised board with the move completed
  revised_board = board.clone
  revised_board[origin.first] = nil
  revised_board[@destination] = @piece
  revised_board.to_move = case board.to_move
                          when "w" then "b"
                          when "b" then "w"
                          end
  revised_board.enpassant_target = "-"
  if @is_capture
    revised_board.halfmove_clock = 0
  else
    revised_board.halfmove_clock += 1
  end
  revised_board.fullmove_number += 1 if board.to_move == "b"

  return revised_board
end

#to_s ⇒ Object 



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# File 'lib/chess_data/moves.rb', line 468

def to_s
  @move_string
end