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|
-module(gap@myers).
-compile([no_auto_import, nowarn_unused_vars, nowarn_unused_function]).
-export([difference/2]).
-export_type([edit/1, path/1, status/1]).
-type edit(FUV) :: {eq, list(FUV)} | {del, list(FUV)} | {ins, list(FUV)}.
-type path(FUW) :: {path,
integer(),
integer(),
list(FUW),
list(FUW),
list(edit(FUW))}.
-type status(FUX) :: {done, list(edit(FUX))} |
{next, list(path(FUX))} |
{cont, path(FUX)}.
-spec compact_reverse(list(edit(FVH)), list(edit(FVH))) -> list(edit(FVH)).
compact_reverse(Edits, Acc) ->
case {Edits, Acc} of
{[], Acc@1} ->
Acc@1;
{[{eq, Elem} | Rest], [{eq, Result} | Acc_rest]} ->
compact_reverse(
Rest,
[{eq, gleam@list:flatten([Elem, Result])} | Acc_rest]
);
{[{del, Elem@1} | Rest@1], [{del, Result@1} | Acc_rest@1]} ->
compact_reverse(
Rest@1,
[{del, gleam@list:flatten([Elem@1, Result@1])} | Acc_rest@1]
);
{[{ins, Elem@2} | Rest@2], [{ins, Result@2} | Acc_rest@2]} ->
compact_reverse(
Rest@2,
[{ins, gleam@list:flatten([Elem@2, Result@2])} | Acc_rest@2]
);
{[{eq, Elem@3} | Rest@3], Acc@2} ->
compact_reverse(Rest@3, [{eq, Elem@3} | Acc@2]);
{[{del, Elem@4} | Rest@4], Acc@3} ->
compact_reverse(Rest@4, [{del, Elem@4} | Acc@3]);
{[{ins, Elem@5} | Rest@5], Acc@4} ->
compact_reverse(Rest@5, [{ins, Elem@5} | Acc@4])
end.
-spec move_right(path(FWA)) -> path(FWA).
move_right(Path) ->
case Path of
{path, X, Y, List1, [Elem | Rest], Edits} ->
{path, X + 1, Y, List1, Rest, [{ins, [Elem]} | Edits]};
{path, X@1, Y@1, List1@1, [], Edits@1} ->
{path, X@1 + 1, Y@1, List1@1, [], Edits@1}
end.
-spec move_down(path(FWD)) -> path(FWD).
move_down(Path) ->
case Path of
{path, X, Y, [Elem | Rest], List2, Edits} ->
{path, X, Y + 1, Rest, List2, [{del, [Elem]} | Edits]};
{path, X@1, Y@1, [], List2@1, Edits@1} ->
{path, X@1, Y@1 + 1, [], List2@1, Edits@1}
end.
-spec proceed_path(integer(), integer(), list(path(FVU))) -> {path(FVU),
list(path(FVU))}.
proceed_path(Diag, Limit, Paths) ->
Neg_limit = - Limit,
case {Diag, Limit, Paths} of
{0, 0, [Path]} ->
{Path, []};
{Diag@1, _, [Path@1 | _] = Paths@1} when Diag@1 =:= Neg_limit ->
{move_down(Path@1), Paths@1};
{Diag@2, Limit@1, [Path@2 | _] = Paths@2} when Diag@2 =:= Limit@1 ->
{move_right(Path@2), Paths@2};
{_, _, [Path1, Path2 | Rest]} ->
case erlang:element(3, Path1) > erlang:element(3, Path2) of
true ->
{move_right(Path1), [Path2 | Rest]};
false ->
{move_down(Path2), [Path2 | Rest]}
end
end.
-spec follow_snake(path(FWG)) -> status(FWG).
follow_snake(Path) ->
case Path of
{path, X, Y, [Elem1 | Rest1], [Elem2 | Rest2], Edits} when Elem1 =:= Elem2 ->
follow_snake(
{path, X + 1, Y + 1, Rest1, Rest2, [{eq, [Elem1]} | Edits]}
);
{path, _, _, [], [], Edits@1} ->
{done, Edits@1};
_ ->
{cont, Path}
end.
-spec each_diagonal(integer(), integer(), list(path(FVO)), list(path(FVO))) -> status(FVO).
each_diagonal(Diag, Limit, Paths, Next_paths) ->
case Diag > Limit of
true ->
{next, gleam@list:reverse(Next_paths)};
false ->
{Path, Rest} = proceed_path(Diag, Limit, Paths),
case follow_snake(Path) of
{cont, Path@1} ->
each_diagonal(Diag + 2, Limit, Rest, [Path@1 | Next_paths]);
Other ->
Other
end
end.
-spec find_script(integer(), integer(), list(path(FVD))) -> list(edit(FVD)).
find_script(Envelope, Max, Paths) ->
case Envelope > Max of
true ->
[];
false ->
case each_diagonal(- Envelope, Envelope, Paths, []) of
{done, Edits} ->
compact_reverse(Edits, []);
{next, Paths@1} ->
find_script(Envelope + 1, Max, Paths@1);
_ ->
erlang:error(#{gleam_error => panic,
message => <<"Didn't expect a Cont here"/utf8>>,
module => <<"gap/myers"/utf8>>,
function => <<"find_script"/utf8>>,
line => 35})
end
end.
-spec difference(list(FUY), list(FUY)) -> list(edit(FUY)).
difference(List1, List2) ->
Path = {path, 0, 0, List1, List2, []},
find_script(0, gleam@list:length(List1) + gleam@list:length(List2), [Path]).
|
