Refactored valid move handling

Author: istateside

chess_board.rb

@@ -38,7 +38,7 @@ def place_pieces
 
   def place_pawn_row(row, color)
     @board[row].each_with_index do |spot, i|
-       @board[row][i] = Pawn.new([row, i], self, color)
+       self[[row, i]] = Pawn.new([row, i], self, color)
      end
 
      nil
@@ -70,8 +70,12 @@ def display
     nil
   end
 
-  def find_king(color)
-    @board.flatten.each do |piece|
+  def pieces
+    @board.flatten.compact
+  end
+
+  def find_king_pos(color)
+    self.pieces.each do |piece|
       if piece.class == King && piece.color == color
         return piece.pos
       end
@@ -81,34 +85,35 @@ def find_king(color)
   end
 
   def in_check?(color)
-    king_pos = find_king(color)
-    @board.flatten.compact.each do |piece|
+    king_pos = find_king_pos(color)
+    self.pieces.each do |piece|
       next if piece.color == color
       return true if piece.moves.include?(king_pos)
     end
 
     false
   end
 
+  def pos_on_board?(pos)
+    row, col = pos
+    row.between?(0, height - 1) && col.between?(0, width - 1)
+  end
+
   def move!(start, end_pos)
+    return unless pos_on_board?(start) && pos_on_board?(end_pos)
     piece = self[start]
-    # changes piece.pos to end_pos
     piece.pos = end_pos
-
-    # changes Board positions
     self[start], self[end_pos] = nil, piece
 
     nil
   end
 
   def move(start, end_pos)
-    # finds piece at start position
     piece = self[start]
     if piece.nil?
       raise "No piece at start position."
     end
 
-    # checks piece.moves for end_pos
     unless piece.moves.include?(end_pos)
       raise "Can't move to that position."
     end
@@ -117,14 +122,11 @@ def move(start, end_pos)
       raise "Move will leave you in check."
     end
 
-    piece.pos = end_pos
-    self[start], self[end_pos] = nil, piece
-
-    nil
+    move!(start, end_pos)
   end
 
   def checkmate?(color)
-    pieces = @board.flatten.compact.select { |piece| piece.color == color }
+    pieces = self.pieces.select { |piece| piece.color == color }
     pieces.all? { |piece| piece.valid_moves.empty? }
   end
 

piece.rb

@@ -26,6 +26,10 @@ def valid_moves
   def valid_move?(target)
     duped_board = @board.dup
     duped_board.move!(@pos, target)
-    !duped_board.in_check?(self.color)
+    return false if duped_board.in_check?(self.color)
+    return false unless move_within_boundaries?(target)
+    return false if !@board[target].nil? && @board[target].color == self.color
+
+    true
   end
 end

sliding_piece.rb

@@ -7,11 +7,8 @@ def moves
       current_pos = @pos
       loop do
         next_move = vector_sum([current_pos, dir])
-        break unless move_within_boundaries?(next_move)
-        break if !@board[next_move].nil? && @board[next_move].color == self.color
         moves << next_move
-        break unless @board[next_move].nil? #change .empty? to whatever call
-
+        break unless move_within_boundaries?(next_move) && @board[next_move].nil?
         current_pos = next_move
       end
     end

stepping_piece.rb

@@ -5,8 +5,6 @@ def moves
     moves = []
     move_dirs.each do |dir|
       next_move = vector_sum([pos, dir])
-      next unless move_within_boundaries?(next_move)
-      next if !@board[next_move].nil? && @board[next_move].color == self.color
       moves << next_move
     end
 

vector_sum.rb

@@ -4,5 +4,6 @@ def vector_sum(vectors)
     result[0] += vec[0]
     result[1] += vec[1]
   end
+
   result
 end