001/src/time.erl

   1 -module(time).
   2 -behaviour(gen_server).
   3
   4
   5 %% API
   6 -export([start_link/2
   7         ,cast/1
   8         ]).
   9
  10 %% Callbacks
  11 -export([init/1
  12         ,handle_call/3
  13         ,handle_cast/2
  14         ,handle_info/2
  15         ,terminate/2
  16         ,code_change/3
  17         ]).
  18
  19
  20 -define(INTERVAL, 0).  % In milliseconds
  21
  22 -define(CHAR_DEAD,   32).  % Space
  23 -define(CHAR_ALIVE, 111).  % o
  24 -define(CHAR_BAR,    61).  % =
  25
  26
  27 -record(state, {x               :: integer()
  28                ,cells           :: list(atom())
  29                ,num_cells       :: integer()
  30                ,state_pairs     :: list(tuple(integer(), integer())) | []
  31                ,replies_pending :: integer()
  32                ,gen_count = 0   :: integer()
  33                }).
  34
  35
  36 %% ============================================================================
  37 %% API
  38 %% ============================================================================
  39
  40 start_link(X, Cells) ->
  41     ServerName = {local, ?MODULE},
  42     Args = [X, Cells],
  43     Opts = [],
  44     gen_server:start_link(ServerName, ?MODULE, Args, Opts).
  45
  46
  47 cast(Msg) ->
  48     gen_server:cast(?MODULE, Msg).
  49
  50
  51 %% ============================================================================
  52 %% Callbacks
  53 %% ============================================================================
  54
  55 init([X, Cells]) ->
  56     State = #state{x=X
  57                   ,cells=Cells
  58                   ,num_cells=length(Cells)
  59                   ,state_pairs=[]
  60                   ,replies_pending=0
  61                   },
  62     cast(next_tick),
  63     {ok, State}.
  64
  65
  66 terminate(_Reason, State) ->
  67     {ok, State}.
  68
  69
  70 code_change(_Old, State, _Other) ->
  71     {ok, State}.
  72
  73
  74 handle_call(_Msg, _From, State) ->
  75     {reply, ok, State}.
  76
  77
  78 handle_cast(next_tick, #state{cells=Cells, num_cells=NumCells, state_pairs=[]}=State) ->
  79     ok = send_all(Cells, tick),
  80     {noreply, State#state{replies_pending=NumCells}};
  81
  82 handle_cast({tock, {ID, CellState}},
  83     #state{x=X
  84           ,state_pairs=StatePairs
  85           ,replies_pending=RepliesPending
  86           ,gen_count=GenCount
  87           }=State) ->
  88
  89     NewStatePairs = [{ID, CellState} | StatePairs],
  90     NewRepliesPending = RepliesPending - 1,
  91     NewState = State#state{replies_pending=NewRepliesPending},
  92
  93     case NewRepliesPending of
  94         0 ->
  95             NewGenCount = GenCount + 1,
  96             SortedStatePairs = lists:sort(NewStatePairs),
  97             StateChars = [state_to_char(S) || {_, S} <- SortedStatePairs],
  98             ok = do_print_bar(X),
  99             ok = io:format("GENERATIONS: ~b~n", [NewGenCount]),
 100             ok = do_print_bar(X),
 101             ok = do_print_state_chars(X, StateChars),
 102             ok = do_print_bar(X),
 103             ok = timer:sleep(?INTERVAL),
 104             cast(next_tick),
 105             {noreply, NewState#state{state_pairs=[], gen_count=NewGenCount}};
 106
 107         _N ->
 108             {noreply, NewState#state{state_pairs=NewStatePairs}}
 109     end;
 110
 111 handle_cast(_Msg, State) ->
 112     {noreply, State}.
 113
 114
 115 handle_info(_Msg, State) ->
 116     {noreply, State}.
 117
 118
 119 %% ============================================================================
 120 %% Internal
 121 %% ============================================================================
 122
 123 send_all([], _) -> ok;
 124 send_all([PID | PIDs], Msg) ->
 125     PID ! Msg,
 126     send_all(PIDs, Msg).
 127
 128
 129 state_to_char(0) -> ?CHAR_DEAD;
 130 state_to_char(1) -> ?CHAR_ALIVE.
 131
 132
 133 do_print_state_chars(_, []) -> ok;
 134 do_print_state_chars(X, Chars) ->
 135     {XChars, RestChars} = lists:split(X, Chars),
 136     ok = io:format([XChars, $\n]),
 137     do_print_state_chars(X, RestChars).
 138
 139
 140 do_print_bar(X) ->
 141     io:format("~s~n", [[?CHAR_BAR || _ <- lists:seq(1, X - 1)]]).