001/src/life_time.erl

   1 -module(life_time).
   2 -behaviour(gen_server).
   3
   4
   5 %% API
   6 -export([start_link/3
   7         ,tock/2
   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, 100).  % In milliseconds
  21
  22 -define(CHAR_DEAD,   32).  % Space
  23 -define(CHAR_ALIVE, 111).  % o
  24 -define(CHAR_BAR,    45).  % -
  25
  26
  27 -record(state, {x               :: integer()
  28                ,y               :: integer()
  29                ,cells           :: list(atom())
  30                ,num_cells       :: integer()
  31                ,state_pairs     :: list(tuple(integer(), integer())) | []
  32                ,replies_pending :: integer()
  33                ,gen_count = 0   :: integer()
  34                }).
  35
  36
  37 %% ============================================================================
  38 %% API
  39 %% ============================================================================
  40
  41 start_link(X, Y, Cells) ->
  42     ServerName = {local, ?MODULE},
  43     Args = [X, Y, Cells],
  44     Opts = [],
  45     gen_server:start_link(ServerName, ?MODULE, Args, Opts).
  46
  47
  48 tock(CellID, CellState) ->
  49     gen_server:cast(?MODULE, {tock, {CellID, CellState}}).
  50
  51
  52 %% ============================================================================
  53 %% Callbacks
  54 %% ============================================================================
  55
  56 init([X, Y, Cells]) ->
  57     State = #state{x=X
  58                   ,y=Y
  59                   ,cells=Cells
  60                   ,num_cells=length(Cells)
  61                   ,state_pairs=[]
  62                   ,replies_pending=0
  63                   },
  64     schedule_next_tick(),
  65     {ok, State}.
  66
  67
  68 terminate(_Reason, State) ->
  69     {ok, State}.
  70
  71
  72 code_change(_Old, State, _Other) ->
  73     {ok, State}.
  74
  75
  76 handle_call(_Msg, _From, State) ->
  77     {reply, ok, State}.
  78
  79
  80 handle_cast(next_tick,
  81     #state{cells=Cells
  82           ,num_cells=NumCells
  83           ,state_pairs=[]
  84           }=State) ->
  85
  86     ok = cast_all(Cells, tick),
  87     {noreply, State#state{replies_pending=NumCells}};
  88
  89 handle_cast({tock, {ID, CellState}},
  90     #state{x=X
  91           ,y=Y
  92           ,state_pairs=StatePairs
  93           ,replies_pending=RepliesPending
  94           ,gen_count=GenCount
  95           ,num_cells=NumCells
  96           }=State) ->
  97
  98     NewStatePairs = [{ID, CellState} | StatePairs],
  99     NewRepliesPending = RepliesPending - 1,
 100     NewState = State#state{replies_pending=NewRepliesPending},
 101
 102     case NewRepliesPending of
 103         0 ->
 104             NewGenCount = GenCount + 1,
 105             SortedStatePairs = lists:sort(
 106                 fun({A, _}, {B, _}) -> A < B end,
 107                 NewStatePairs
 108             ),
 109             StateChars = [state_to_char(S) || {_, S} <- SortedStatePairs],
 110
 111             ok = io:format(
 112                 "X: ~b Y: ~b CELLS: ~b GENERATIONS: ~b~n",
 113                 [X, Y, NumCells, NewGenCount]
 114             ),
 115             ok = do_print_bar(X),
 116
 117             ok = do_print_state_chars(X, StateChars),
 118
 119             ok = timer:sleep(?INTERVAL),
 120             schedule_next_tick(),
 121             {noreply, NewState#state{state_pairs=[], gen_count=NewGenCount}};
 122
 123         _N ->
 124             {noreply, NewState#state{state_pairs=NewStatePairs}}
 125     end;
 126
 127 handle_cast(_Msg, State) ->
 128     {noreply, State}.
 129
 130
 131 handle_info(_Msg, State) ->
 132     {noreply, State}.
 133
 134
 135 %% ============================================================================
 136 %% Internal
 137 %% ============================================================================
 138
 139 schedule_next_tick() ->
 140     gen_server:cast(?MODULE, next_tick).
 141
 142
 143 cast_all([], _) -> ok;
 144 cast_all([Server | Servers], Msg) ->
 145     ok = gen_server:cast(Server, Msg),
 146     cast_all(Servers, Msg).
 147
 148
 149 state_to_char(0) -> ?CHAR_DEAD;
 150 state_to_char(1) -> ?CHAR_ALIVE.
 151
 152
 153 do_print_state_chars(_, []) -> ok;
 154 do_print_state_chars(X, Chars) ->
 155     {XChars, RestChars} = lists:split(X, Chars),
 156     ok = io:format([XChars, $\n]),
 157     do_print_state_chars(X, RestChars).
 158
 159
 160 do_print_bar(X) ->
 161     io:format("~s~n", [[?CHAR_BAR || _ <- lists:seq(1, X - 1)]]).