+++ /dev/null
--module(life).
-
--export([bang/1]).
-
-
--define(DIRECTIONS, ['N', 'NE', 'E', 'SE', 'S', 'SW', 'W', 'NW']).
-
--define(INTERVAL, 0). % In milliseconds
-
--define(CHAR_DEAD, 32). % Space
--define(CHAR_ALIVE, 111). % o
--define(CHAR_BAR, 61). % =
-
-
-%% ============================================================================
-%% Life processes
-%% ============================================================================
-
-%% ----------------------------------------------------------------------------
-%% Big bang
-%% ----------------------------------------------------------------------------
-
-bang([X, Y]) ->
- bang(atom_to_integer(X), atom_to_integer(Y)).
-
-
-bang(X, Y) ->
- N = X * Y,
- CellIDs = lists:seq(1, N),
-
- Graph =
- lists:foldl(
- fun(ID, Pairs) ->
- Neighbors = [
- integer_to_atom(neighbor_id(D, X, ID))
- || D <- ?DIRECTIONS
- ],
- [{integer_to_atom(ID), Neighbors} | Pairs]
- end,
- [],
- CellIDs
- ),
-
- Parent = self(),
-
- lists:foreach(
- fun({ID, Neighbors}) ->
- register(
- ID,
- spawn(fun() -> cell(ID, Parent, Neighbors) end)
- )
- end,
- [{ID, filter_offsides(N, Neighbors)} || {ID, Neighbors} <- Graph]
- ),
-
- CellNames = [integer_to_atom(ID) || ID <- CellIDs],
-
- tick(X, CellNames).
-
-
-%% ----------------------------------------------------------------------------
-%% Tick / tock
-%% ----------------------------------------------------------------------------
-
-tick(X, Cells) ->
- ok = send_all(Cells, {tick, self()}),
- All = Cells,
- Pending = Cells,
- StatePairs = [],
- tock(X, All, Pending, StatePairs).
-
-
-tock(X, All, [], StatePairs) ->
- States =
- lists:foldl(
- fun({_ID, State}, States) -> [State | States] end,
- [],
- lists:sort(
- fun({A, _}, {B, _}) ->
- atom_to_integer(A) < atom_to_integer(B)
- end,
- StatePairs
- )
- ),
- ok = do_print_bar(X),
- ok = do_print_states(X, States),
- ok = do_print_bar(X),
- ok = timer:sleep(?INTERVAL),
- tick(X, All);
-
-tock(X, All, Pending, StatePairs) ->
- receive
- {tock, {ID, State}} ->
- NewPending = lists:delete(ID, Pending),
- NewStatePairs = [{ID, State} | StatePairs],
- tock(X, All, NewPending, NewStatePairs)
- end.
-
-
-%% ----------------------------------------------------------------------------
-%% Cell
-%% ----------------------------------------------------------------------------
-
-% Init
-cell(MyID, MyParent, MyNeighbors) ->
- MyState = crypto:rand_uniform(0, 2),
- cell(MyID, MyParent, MyNeighbors, MyState).
-
-
-cell(MyID, MyParent, MyNeighbors, MyState) ->
- receive
- {tick, MyParent} ->
- ok = send_all(MyNeighbors, {request_state, MyID}),
- cell(MyID, MyParent, MyNeighbors, MyState, {MyNeighbors, []})
- end.
-
-
-% All neighbors replied
-cell(MyID, MyParent, MyNeighbors, MyState, {[], States}) ->
- LiveNeighbors = lists:sum(States),
- MyNewState = new_state(MyState, LiveNeighbors),
- MyParent ! {tock, {MyID, MyState}},
- cell(MyID, MyParent, MyNeighbors, MyNewState);
-
-% Awaiting requests and replies
-cell(MyID, MyParent, MyNeighbors, MyState, {Pending, States}) ->
- receive
- {request_state, ID} ->
- ID ! {response_state, MyID, MyState},
- cell(MyID, MyParent, MyNeighbors, MyState, {Pending, States});
-
- {response_state, ID, State} ->
- NewPending = lists:delete(ID, Pending),
- NewStates = [State | States],
- cell(MyID, MyParent, MyNeighbors, MyState, {NewPending, NewStates})
- end.
-
-
-%% ============================================================================
-%% Rules
-%% ============================================================================
-
-new_state(1, LiveNeighbors) when LiveNeighbors < 2 -> 0;
-new_state(1, LiveNeighbors) when LiveNeighbors < 4 -> 1;
-new_state(1, LiveNeighbors) when LiveNeighbors > 3 -> 0;
-new_state(0, LiveNeighbors) when LiveNeighbors =:= 3 -> 1;
-new_state(State, _LiveNeighbors) -> State.
-
-
-neighbor_id(Direction, X, ID) ->
- ID + offset(Direction, X).
-
-
-offset('N' , X) -> ensure_negative(X);
-offset('NE', X) -> ensure_negative(X - 1);
-offset('E' , _) -> 1;
-offset('SE', X) -> X + 1;
-offset('S' , X) -> X;
-offset('SW', X) -> X - 1;
-offset('W' , _) -> ensure_negative( 1);
-offset('NW', X) -> ensure_negative(X + 1).
-
-
-filter_offsides(N, IDs) ->
- [ID || ID <- IDs, is_onside(N, atom_to_integer(ID))].
-
-
-is_onside(_, ID) when ID < 1 -> false;
-is_onside(N, ID) when ID > N -> false;
-is_onside(_, _) -> true.
-
-
-%% ============================================================================
-%% Plumbing
-%% ============================================================================
-
-ensure_negative(N) when N < 0 -> N;
-ensure_negative(N) -> -(N).
-
-
-atom_to_integer(Atom) ->
- list_to_integer(atom_to_list(Atom)).
-
-
-integer_to_atom(Integer) ->
- list_to_atom(integer_to_list(Integer)).
-
-
-send_all([], _) -> ok;
-send_all([PID | PIDs], Msg) ->
- PID ! Msg,
- send_all(PIDs, Msg).
-
-
-do_print_states(_, []) -> ok;
-do_print_states(X, States) ->
- {XStates, RestStates} = lists:split(X, States),
- ok = io:format([state_to_char(S) || S <- XStates] ++ "\n"),
- do_print_states(X, RestStates).
-
-
-do_print_bar(X) ->
- io:format("~s~n", [[?CHAR_BAR || _ <- lists:seq(1, X - 1)]]).
-
-
-state_to_char(0) -> ?CHAR_DEAD;
-state_to_char(1) -> ?CHAR_ALIVE.
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