Class: Egd::FenDifferenceDiscerner

Inherits:
Object
  • Object
show all
Defined in:
lib/egd/fen_difference_discerner.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(start_fen: nil, move:, end_fen:) ⇒ FenDifferenceDiscerner

Egd::FenDifferenceDiscerner.new(start_fen:, end_fen:).call



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# File 'lib/egd/fen_difference_discerner.rb', line 13

def initialize(start_fen: nil, move:, end_fen:)
  @start_fen = start_fen || Egd::FenBuilder::NULL_FEN
  @move = move
  @end_fen = end_fen
end

Instance Attribute Details

#end_fen ⇒ Object (readonly)

Theoretically a start and end fen would suffice, but having move in SAN, which we do, allows skipping some hard procesing parts.



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# File 'lib/egd/fen_difference_discerner.rb', line 10

def end_fen
  @end_fen
end

#move ⇒ Object (readonly)

Theoretically a start and end fen would suffice, but having move in SAN, which we do, allows skipping some hard procesing parts.



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# File 'lib/egd/fen_difference_discerner.rb', line 10

def move
  @move
end

#start_fen ⇒ Object (readonly)

Theoretically a start and end fen would suffice, but having move in SAN, which we do, allows skipping some hard procesing parts.



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# File 'lib/egd/fen_difference_discerner.rb', line 10

def start_fen
  @start_fen
end

Instance Method Details

#call ⇒ Object 



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# File 'lib/egd/fen_difference_discerner.rb', line 19

def call
  # quickreturn with possible special cases
  case move
  when "O-O"
    return special_case_short_castle(Egd::Procedures.parse_fen(start_fen)[:to_move])
  when "O-O-O"
    return special_case_long_castle(Egd::Procedures.parse_fen(start_fen)[:to_move])
  when %r'\A[a-h]x[a-h]\d' # pawn x pawn, possible en-passant
    return special_case_ep_capture if special_case_ep_capture
  end

  # entering long processing of regular moves

  changes = {
    "lran" => lran, # FEN
    "from_square" => from_square, # FEN # b2
    "to_square" => to_square, # move b3
    "piece" => piece, # move p
    "move_type" => move_type,
  }

  changes.merge!("captured_piece" => captured_piece) if captured_piece
  changes.merge!("promotion" => promotion) if promotion

  changes
end