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-module(bm_location).
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% TYPES %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-type type() :: ({non_neg_integer(), non_neg_integer()} | 'nowhere').
-export_type([type/0]).
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% EXPORTS %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-export
(
[
decode/1,
encode/1,
get_nowhere/0
]
).
-export
(
[
apply_direction/2,
dist/2
]
).
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% LOCAL FUNCTIONS %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-spec validate ({integer(), integer()}) -> type().
validate ({X, Y}) ->
if
(X < 0) -> nowhere;
(Y < 0) -> nowhere;
true -> {X, Y}
end.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% EXPORTED FUNCTIONS %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-spec get_nowhere () -> type().
get_nowhere () -> nowhere.
-spec apply_direction (bm_direction:enum(), type()) -> type().
apply_direction (left, {X, Y}) ->
validate({(X - 1), Y});
apply_direction (right, {X, Y}) ->
validate({(X + 1), Y});
apply_direction (up, {X, Y}) ->
validate({X, (Y - 1)});
apply_direction (down, {X, Y}) ->
validate({X, (Y + 1)});
apply_direction (_, nowhere) ->
error("Trying to move from 'nowhere'."),
nowhere.
-spec dist(type(), type()) -> non_neg_integer().
dist ({OX, OY}, {DX, DY}) ->
(abs(DY - OY) + abs(DX - OX));
dist (_, _) ->
error("Trying to measure distance to 'nowhere'"),
999.
-spec encode (type()) -> {list(any())}.
encode ({X, Y}) ->
{
[
{<<"x">>, X},
{<<"y">>, Y}
]
};
encode (nowhere) ->
{
[
{<<"x">>, -1},
{<<"y">>, -1}
]
}.
-spec decode (map()) -> type().
decode (Map) ->
X = maps:get(<<"x">>, Map),
Y = maps:get(<<"y">>, Map),
true = (is_integer(X) and is_integer(Y)),
validate({X, Y}).
|
