Class: Move

Inherits:
Object
  • Object
show all
Defined in:
lib/bangkok/move.rb

Overview

A Move is a single piece’s move in a chess match. There are two Move objects created for each chess match move: one for white and one for black.

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(color, text) ⇒ Move

Parse the chess piece move text and set piece, square, and modifier.



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# File 'lib/bangkok/move.rb', line 10

def initialize(color, text)
  @color = color              # :white or :black
  @orig_text = text

  # Note: I don't have to worry about "e.p." en passant notation; the data
  # files do not use that.
  case text
  when 'O-O-O', 'O-O', '0-0-0', '0-0'
    @modifier = text.gsub(/0/, 'O') # zeroes to capital o's
    @piece = 'K'
    @square = Square::OFF_BOARD # Not really, of course; square is never used
  when /^([KQRBNa-h1-8])x([a-h][1-8])(.*)$/
    piece_or_from_rank_or_file, file_and_rank, @modifier = $1, $2, $3
    @square = Square.new(file_and_rank)
    case piece_or_from_rank_or_file
    when /[a-h1-8]/           # first char is file or rank; it's a pawn
      @piece = 'P'
      @from_rank_or_file = Square.new(piece_or_from_rank_or_file)
    else                      # first char is piece name
      @piece = piece_or_from_rank_or_file
    end
    @modifier ||= ''
    @modifier << 'x'
  when /^([KQRBN]?)([a-h1-8]?)([a-h][1-8])(.*)$/
    @piece, from_rank_or_file, file_and_rank, @modifier = $1, $2, $3, $4
    @square = Square.new(file_and_rank)
    unless from_rank_or_file.empty?
      @from_rank_or_file = Square.new(from_rank_or_file) 
    end
  else
    raise "I can't understand the move \"#{@orig_text}\""
  end

  @piece = 'P' if @piece.empty?
  @piece = @piece.intern
end

Instance Attribute Details

#color ⇒ Object (readonly)

Returns the value of attribute color.



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# File 'lib/bangkok/move.rb', line 7

def color
  @color
end

#from_rank_or_file ⇒ Object (readonly)

Returns the value of attribute from_rank_or_file.



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# File 'lib/bangkok/move.rb', line 7

def from_rank_or_file
  @from_rank_or_file
end

#modifier ⇒ Object (readonly)

Returns the value of attribute modifier.



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# File 'lib/bangkok/move.rb', line 7

def modifier
  @modifier
end

#piece ⇒ Object (readonly)

Returns the value of attribute piece.



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# File 'lib/bangkok/move.rb', line 7

def piece
  @piece
end

#square ⇒ Object (readonly)

Returns the value of attribute square.



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# File 'lib/bangkok/move.rb', line 7

def square
  @square
end

Instance Method Details

#bad_move? ⇒ Boolean

Returns true if this move was a bad one

Returns:

  • (Boolean) 


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# File 'lib/bangkok/move.rb', line 98

def bad_move?
  has_modifier?('?') && !blunder?
end

#blunder? ⇒ Boolean

Returns true if this move was a blunder

Returns:

  • (Boolean) 


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# File 'lib/bangkok/move.rb', line 103

def blunder?
  has_modifier?('??')
end

#capture? ⇒ Boolean

Returns true if this is a capture

Returns:

  • (Boolean) 


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# File 'lib/bangkok/move.rb', line 58

def capture?
  has_modifier?('x')
end

#castle? ⇒ Boolean

Returns true if this is a castle (either side)

Returns:

  • (Boolean) 


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# File 'lib/bangkok/move.rb', line 63

def castle?
  has_modifier?('O-O')  # Also true if O-O-O
end

#check? ⇒ Boolean

Returns true if this move results in a check

Returns:

  • (Boolean) 


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# File 'lib/bangkok/move.rb', line 83

def check?
  has_modifier?('+')
end

#checkmate? ⇒ Boolean

Returns true if this move results in a checkmate

Returns:

  • (Boolean) 


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# File 'lib/bangkok/move.rb', line 88

def checkmate?
  has_modifier?('#')
end

#good_move? ⇒ Boolean

Returns true if this move was a good one

Returns:

  • (Boolean) 


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# File 'lib/bangkok/move.rb', line 93

def good_move?
  has_modifier?('!')
end

#has_modifier?(str) ⇒ Boolean

Returns true if @modifier is not null and includes str.

Returns:

  • (Boolean) 


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# File 'lib/bangkok/move.rb', line 52

def has_modifier?(str)
  return false unless @modifier
  return @modifier.include?(str)
end

#kingside_castle? ⇒ Boolean

Returns true if this is a kingside castle

Returns:

  • (Boolean) 


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# File 'lib/bangkok/move.rb', line 73

def kingside_castle?
  has_modifier?('O-O') && !queenside_castle?
end

#pawn_promotion? ⇒ Boolean

Returns true if this move results in a pawn promotion

Returns:

  • (Boolean) 


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# File 'lib/bangkok/move.rb', line 78

def pawn_promotion?
  has_modifier?('Q')
end

#queenside_castle? ⇒ Boolean

Returns true if this is a queenside castle

Returns:

  • (Boolean) 


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# File 'lib/bangkok/move.rb', line 68

def queenside_castle?
  has_modifier?('O-O-O')
end

#to_s ⇒ Object 



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# File 'lib/bangkok/move.rb', line 47

def to_s
  return @orig_text
end