1 files changed, 155 insertions, 0 deletions
diff --git a/lib/dialyzer/test/file_utils.erl b/lib/dialyzer/test/file_utils.erl
new file mode 100644
index 0000000000..36b368760c
--- /dev/null
+++ b/lib/dialyzer/test/file_utils.erl
@@ -0,0 +1,155 @@
+-module(file_utils).
+
+-export([list_dir/3, file_type/1, diff/2]).
+
+-include_lib("kernel/include/file.hrl").
+
+-type ext_posix()::posix()|'badarg'.
+-type posix()::atom().
+
+-spec list_dir(file:filename(), string(), boolean()) ->
+		      {error, ext_posix()} | {ok, [file:filename()]}.
+
+list_dir(Dir, Extension, Dirs) ->
+    case file:list_dir(Dir) of
+	{error, _} = Error-> Error;
+	{ok, Filenames} ->
+	    FullFilenames = [filename:join(Dir, F) || F <-Filenames ],
+	    Matches1 = case Dirs of
+			   true ->
+			       [F || F <- FullFilenames,
+				     file_type(F) =:= {ok, 'directory'}];
+			   false -> []
+		       end,
+	    Matches2 = [F || F <- FullFilenames,
+			     file_type(F) =:= {ok, 'regular'},
+			     filename:extension(F) =:= Extension],
+	    {ok, lists:sort(Matches1 ++ Matches2)}
+    end.
+
+-spec file_type(file:filename()) ->
+		       {ok, 'device' | 'directory' | 'regular' | 'other'} |
+		       {error, ext_posix()}.
+
+file_type(Filename) ->
+    case file:read_file_info(Filename) of
+	{ok, FI} -> {ok, FI#file_info.type};
+	Error    -> Error
+    end.
+
+-type diff_result()::'same' | {'differ', diff_list()} |
+		     {error, {file:filename(), term()}}.
+-type diff_list()::[{id(), line(), string()}].
+-type id()::'new'|'old'.
+-type line()::non_neg_integer().
+
+-spec diff(file:filename(), file:filename()) -> diff_result().
+
+diff(Filename1, Filename2) ->
+    File1 =
+	case file:open(Filename1, [read]) of
+	    {ok, F1} -> {file, F1};
+	    _        -> empty
+	end,
+    File2 =
+	case file:open(Filename2, [read]) of
+	    {ok, F2} -> {file, F2};
+	    _        -> empty
+	end,
+    case diff1(File1, File2) of
+	{error, {N, Error}} ->
+	    case N of
+		1 -> {error, {Filename1, Error}};
+		2 -> {error, {Filename2, Error}}
+	    end;
+	[]       -> 'same';
+	DiffList -> {'differ', DiffList}
+    end.
+
+diff1(File1, File2) ->
+    case file_to_lines(File1) of
+	{error, Error} -> {error, {1, Error}};
+	Lines1 ->
+	    case file_to_lines(File2) of
+		{error, Error} -> {error, {2, Error}};
+		Lines2 ->
+		    Common = lcs_fast(Lines1, Lines2),
+		    diff2(Lines1, 1, Lines2, 1, Common, [])
+	    end
+    end.
+
+diff2([], _, [], _, [], Acc) -> lists:keysort(2,Acc);
+diff2([H1|T1], N1, [], N2, [], Acc) ->
+    diff2(T1, N1+1, [], N2, [], [{new, N1, H1}|Acc]);
+diff2([], N1, [H2|T2], N2, [], Acc) ->
+    diff2([], N1, T2, N2+1, [], [{old, N2, H2}|Acc]);
+diff2([H1|T1], N1, [H2|T2], N2, [], Acc) ->
+    diff2(T1, N1+1, T2, N2+1, [], [{new, N1, H1}, {old, N2, H2}|Acc]);
+diff2([H1|T1]=L1, N1, [H2|T2]=L2, N2, [HC|TC]=LC, Acc) ->
+    case H1 =:= H2 of
+	true  -> diff2(T1, N1+1, T2, N2+1, TC, Acc);
+	false ->
+	    case H1 =:= HC of
+		true  -> diff2(L1, N1, T2, N2+1, LC, [{old, N2, H2}|Acc]);
+		false -> diff2(T1, N1+1, L2, N2, LC, [{new, N1, H1}|Acc])
+	    end
+    end.
+
+-spec lcs_fast([string()], [string()]) -> [string()].
+
+lcs_fast(S1, S2) ->
+  M = length(S1),
+  N = length(S2),
+  Acc = array:new(M*N, {default, 0}),
+  {L, _} = lcs_fast(S1, S2, 1, 1, N, Acc), 
+  L.
+
+-spec lcs_fast([string()], [string()],
+	       pos_integer(), pos_integer(),
+	       non_neg_integer(), array()) -> {[string()], array()}.
+
+lcs_fast([], _, _, _, _, Acc) ->
+  {[], Acc};
+lcs_fast(_, [], _, _, _, Acc) ->
+  {[], Acc};
+lcs_fast([H1|T1] = S1, [H2|T2] = S2, N1, N2, N, Acc) ->
+  I = (N1-1) * N + N2 - 1,
+  case array:get(I, Acc) of
+    0 ->
+      case string:equal(H1, H2) of
+	true ->
+	  {T, NAcc} = lcs_fast(T1, T2, N1+1, N2+1, N, Acc),
+	  L = [H1|T],
+	  {L, array:set(I, L, NAcc)};
+	false ->
+	  {L1, NAcc1} = lcs_fast(S1, T2, N1, N2+1, N, Acc), 
+	  {L2, NAcc2} = lcs_fast(T1, S2, N1+1, N2, N, NAcc1),
+	  L = longest(L1, L2), 
+	  {L, array:set(I, L, NAcc2)}
+      end;
+    L -> 
+      {L, Acc}
+  end.
+
+-spec longest([string()], [string()]) -> [string()].
+
+longest(S1, S2) ->
+  case length(S1) > length(S2) of
+    true -> S1;
+    false -> S2
+  end.
+
+file_to_lines(empty) ->
+    [];
+file_to_lines({file, File}) ->
+    case file_to_lines(File, []) of
+	{error, _} = Error -> Error;
+	Lines              -> lists:reverse(Lines)
+    end.
+
+file_to_lines(File, Acc) ->
+    case io:get_line(File, "") of
+	{error, _}=Error -> Error;
+	eof              -> Acc;
+	A                -> file_to_lines(File, [A|Acc])
+    end.