lib/games/chess/pgn.rb

   1 require 'strscan'
   2 require 'history'
   3 require 'qtutils'
   4
   5 module Chess
   6
   7 class PGN
   8   ParseError = Class.new(ParseException)
   9
  10   def initialize(serializer, state_factory)
  11     @serializer = serializer
  12     @state_factory = state_factory
  13   end
  14
  15   def write(info, history)
  16     date = if info[:date].respond_to? :strftime
  17       info[:date].strftime('%Y.%m.%d')
  18     else
  19       info[:date]
  20     end
  21     tag(:event, info[:event]) +
  22     tag(:site, info[:site]) +
  23     tag(:date, date) +
  24     tag(:round, info[:round]) +
  25     player_tags(info[:players] || { }) +
  26     tag(:result, result(info[:result])) +
  27     "\n" +
  28     game(history) + " " +
  29     result(info[:result]) + "\n"
  30   end
  31
  32   def read(text, info)
  33     # read tags
  34     scanner = StringScanner.new(text)
  35     while scanner.scan(/\[(.*) "(.*)"\]\n/)
  36       info[scanner[1].downcase.to_sym] = scanner[2]
  37     end
  38     scanner.scan(/\n*/)
  39
  40     # insert players into info[:players]
  41     info[:players] = read_players(info)
  42
  43     state = @state_factory.new
  44     state.setup
  45     history = History.new(state)
  46     index = 1
  47
  48     while scanner.scan(/(\d+)\.\s*/)
  49       if index != scanner[1].to_i
  50         raise ParseError.new("Unexpected index #{index}")
  51       end
  52
  53       wmove = @serializer.deserialize(scanner, state)
  54       raise ParseError.new("Expected move at index #{index}") unless wmove
  55       state = state.dup
  56       state.perform! wmove
  57       history.add_move(state, wmove)
  58
  59       scanner.scan(/\s+/)
  60       bmove = @serializer.deserialize(scanner, state)
  61       break unless bmove
  62       state = state.dup
  63       state.perform! bmove
  64       history.add_move(state, bmove)
  65
  66       scanner.scan(/\s+/)
  67
  68       index += 1
  69     end
  70
  71     result = scanner.scan(/1-0|0-1|1\/2-1\/2|\*/)
  72     info[:result] = result if result
  73     history
  74   end
  75
  76   def tag(key, value)
  77     if value
  78       %{[#{key.to_s.capitalize} "#{value}"]\n}
  79     else
  80       ""
  81     end
  82   end
  83
  84   def read_players(info)
  85     result = {
  86       :white => info[:white],
  87       :black => info[:black] }
  88     info.delete(:white)
  89     info.delete(:black)
  90     result
  91   end
  92
  93   def player_tags(players)
  94     tag(:white, players[:white]) +
  95     tag(:black, players[:black])
  96   end
  97
  98   def result(value)
  99     case value
 100     when String
 101       value
 102     when :white
 103       "1-0"
 104     when :black
 105       "0-1"
 106     when :draw
 107       "1/2-1/2"
 108     else
 109       "*"
 110     end
 111   end
 112
 113   def game(history)
 114     1.to_enum(:step, history.size - 1, 2).map do |i|
 115       wmove = @serializer.serialize(history[i].move, history[i - 1].state)
 116       bmove = if i + 1 < history.size
 117         @serializer.serialize(history[i + 1].move, history[i].state)
 118       end
 119       index = (i + 1) / 2
 120       result = "#{index}.#{wmove}"
 121       result += " #{bmove}" if bmove
 122       result
 123     end.join(' ')
 124   end
 125 end
 126
 127 end