Class: MailChess::Piece::Pawn

Inherits:
Piece
  • Object
show all
Defined in:
lib/mail_chess/pieces/pawn.rb

Overview

Represents a pawn chess piece.

Instance Attribute Summary

Attributes inherited from Piece

#board, #color, #hits, #html, #id, #moves, #type

Class Method Summary collapse

Instance Method Summary collapse

Methods inherited from Piece

#can_hit?, #can_move?, create_tables, #delete!, load!, #move, need_to_create_tables?, #position, #save!

Constructor Details

#initialize(db, piece_id, board = nil) ⇒ Pawn

Calls the superclass.



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# File 'lib/mail_chess/pieces/pawn.rb', line 11

def initialize db, piece_id, board = nil
  super db, piece_id, board
  
  @html = @color == :white ? '♙' : '♟'
end

Class Method Details

.new!(db, board, position, color) ⇒ Object

Overwrite superclass method.



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# File 'lib/mail_chess/pieces/pawn.rb', line 18

def self.new! db, board, position, color
  super db, board, position, color
  
  id = db[:pieces].insert(:type => 'pawn', 
                          :color => color.to_s,
                          :position => position,
                          :board_id => board.id)
                          
  return Pawn.new db, id, board
end

Instance Method Details

#generate_moves ⇒ Object

Generate the possible moves.



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# File 'lib/mail_chess/pieces/pawn.rb', line 30

def generate_moves
  super
  
  r, c = ROWS.index(position[1]), COLS.index(position[0])
  dir = @color == :white ? -1 : 1
  first_step = 
    ((@color == :white and position[1] == 2.to_s) or
     (@color == :black and position[1] == 7.to_s) ? true : false)
  
  # moves
  if (r + dir >= 0 and @color == :white) or (r + dir <= 7 and 
                                             @color == :black)
    f = COLS[c] + ROWS[r + dir]
    @moves << f unless @board.pieces[f]
  end
  
  if (r + dir * 2 >= 0 and @color == :white) or (r + dir * 2 <= 7 and
                                                 @color == :black)
    f = COLS[c] + ROWS[r + dir * 2]
    @moves << f if !@board.pieces[f] and first_step
  end
  
  # hits
  [-1, 1].each do |x|
    if c + x >= 0 and c + x <= 7
      if (r - 1 >= 0 and @color == :white) or (r + 1 <= 7 and
                                               @color == :black)
        f = COLS[c + x] + ROWS[r + dir]
        @hits << f if @board.pieces[f]
      end
    end
  end
end