Module: ChessData::Moves

Defined in:
lib/chess_data/moves.rb

Overview

Moves is a collection of regular expressions and methods to recognise how moves are written in PGN files, and to make the moves on a given board.

As the moves are obtained from PGN files, they are assumed to be correct.

Defined Under Namespace

Classes: KingsideCastles, PawnCapture, PieceMove, PromotionPawnCapture, PromotionPawnMove, QueensideCastles, SimplePawnMove

Constant Summary collapse

Square =

:nodoc: Regular expressions to match each of the move types.

/[a-h][1-8]/
Piece = 
/[KQRBN]/
MatchKingsideCastles = 
/^O-O\+?\Z/
MatchQueensideCastles = 
/^O-O-O\+?\Z/
MatchPieceMove = 
/^(#{Piece})([a-h]?|[1-8]?)x?(#{Square})\+?\Z/
MatchPawnCapture = 
/^([a-h])x(#{Square})\+?\Z/
MatchPromotionPawnMove = 
/^([a-h][18])=([QqRrBbNn])\+?\Z/
MatchSimplePawnMove = 
/^(#{Square})\+?\Z/
MatchPromotionPawnCapture = 
/^([a-h])x([a-h][18])=([QqRrBbNn])\+?\Z/
LegalMove =

Combined regular expression, to match a legal move.

/#{MatchKingsideCastles}|#{MatchQueensideCastles}|#{MatchPieceMove}|#{MatchPawnCapture}|#{MatchPromotionPawnMove}|#{MatchSimplePawnMove}|#{MatchPromotionPawnCapture}/

Class Method Summary collapse

Class Method Details

.can_reach(board, piece, start, finish) ⇒ Object

Return true if given piece can move from start square to finish on given board.



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# File 'lib/chess_data/moves.rb', line 48

def Moves.can_reach board, piece, start, finish
  start = start.upcase
  finish = finish.upcase
  case piece
  when "K", "k" then Moves.king_can_reach start, finish
  when "Q", "q" then Moves.queen_can_reach board, start, finish
  when "R", "r" then Moves.rook_can_reach board, start, finish
  when "B", "b" then Moves.bishop_can_reach board, start,finish
  when "N", "n" then Moves.knight_can_reach start, finish
  end
end

.new_move(string) ⇒ Object

Returns an instance of the appropriate move type.

string

a move read from a PGN file.



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# File 'lib/chess_data/moves.rb', line 34

def Moves.new_move string
  case string
  when MatchKingsideCastles then KingsideCastles.new
  when MatchQueensideCastles then QueensideCastles.new
  when MatchPieceMove then PieceMove.new string
  when MatchPawnCapture then PawnCapture.new string
  when MatchPromotionPawnMove then PromotionPawnMove.new string
  when MatchSimplePawnMove then SimplePawnMove.new string
  when MatchPromotionPawnCapture then PromotionPawnCapture.new string
  else raise InvalidMoveError.new("Invalid move: #{string}")
  end
end