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src/tdiff_debug.erl
-module(tdiff_debug).
-export([svg_diff/3]).
%% @doc Example:
%% ```
%% svg_diff("A cat ate my hat", "A dog ate my shoe", "tdiff-trace.svg").
%% '''
%% The resulting svg file works well in Chrome and Opera.
%%
%% The Sx is (usually) the "old" string.
%% The Sy is (usually) the "new" string.
%% The blue number in the upper left is the D number.
%% Taking a step to the right means deleting that character.
%% Taking a step down means inserting that character.
%%
%% The tdiff algorithm can diff any list of objects, such as lists of
%% lines, lists of words or whatever. However, this tracer is only
%% good at strings (lists of characters). It might produce funny or
%% strange svg files in other cases.
%%
svg_diff(Sx, Sy, DestFileName) ->
Tracer = start_svg_tracer(Sx, Sy, DestFileName),
Res = tdiff:diff(Sx, Sy, [{algorithm_tracer, fun(Ev) -> Tracer ! Ev end}]),
stop_tracer(Tracer),
Res.
start_svg_tracer(Sx, Sy, DestFileName) ->
proc_lib:spawn(fun() -> init_svg_tracer(Sx, Sy, DestFileName) end).
stop_tracer(Pid) ->
MRef = erlang:monitor(process, Pid),
Pid ! {stop, self()},
receive
{Pid, Res} ->
erlang:demonitor(MRef, [flush]),
Res;
{'DOWN', MRef, _, _, Reason} ->
erlang:error({terminated,Reason})
end.
init_svg_tracer(Sx, Sy, DestFileName) ->
FdInfo = open_svg_file(Sx, Sy, DestFileName),
loop_svg_tracer(FdInfo, _D=unknown, Sx, Sy).
loop_svg_tracer(FdInfo, D, Sx, Sy) ->
receive
{final_edit_script, EditScript} ->
print_final_edit_script(FdInfo, EditScript),
loop_svg_tracer(FdInfo, D, Sx, Sy);
{exhausted_kdiagonals, _D} ->
print_svg_d_closed(FdInfo),
loop_svg_tracer(FdInfo, D, Sx, Sy);
{d, NewD} ->
print_svg_d(FdInfo, NewD),
loop_svg_tracer(FdInfo, NewD, Sx, Sy);
{dpath, DPath} ->
print_svg_dpath(FdInfo, DPath),
loop_svg_tracer(FdInfo, D, Sx, Sy);
{stop, From} ->
print_svg_dmax(FdInfo, D),
close_svg_file(FdInfo),
From ! {self(),ok}
end.
-record(fdinfo, {fd, xoffs, yoffs, dx, dy,
pathlinestyle, endpointstyle,
final_pathlinestyle, final_endpointstyle}).
open_svg_file(Sx, Sy, DestFileName) ->
SxLen = length(Sx),
SyLen = length(Sy),
DMax = SxLen + SyLen,
Dx = 10,
Dy = 10,
XOffs = 20,
YOffs = 10,
{ok,Fd} = file:open(DestFileName, [write]),
io:format(
Fd,
"<?xml version=\"1.0\" encoding=\"iso-8859-1\" standalone=\"no\"?>\n"
"<svg xmlns:svg=\"http://www.w3.org/2000/svg\"\n"
" xmlns=\"http://www.w3.org/2000/svg\"\n"
" version=\"1.0\"\n"
" viewBox=\"0 0 ~w ~w\"\n"
" id=\"svg2\">\n"
" <style type=\"text/css\"><![CDATA[\n"
" .border { fill:none; stroke: #000000; stroke-width: 2; }\n"
" .grid { fill:none; stroke: #cccccc; stroke-width: 0.33; }\n"
" .path { fill:none; stroke: #660000; stroke-width: 1; }\n"
" .endpt { fill:#660000; stroke: none; }\n"
" .fpath { fill:none; stroke: #006600; stroke-width: 1; }\n"
" .fendpt { fill:#006600; stroke: none; }\n"
" ]]></style>\n"
" <script><![CDATA[\n"
"function lightup(id) {\n"
" var t = document.getElementById(id)\n"
" t.setAttributeNS(null,\"fill-opacity\", 1);\n"
"}\n"
"function lightdown(id) {\n"
" var t = document.getElementById(id)\n"
" t.setAttributeNS(null,\"fill-opacity\", 0.75);\n"
"}\n"
"var d_min=0;\n"
"var d_max=~w; // upper bound\n"
"var curr_d=0;\n"
"\n"
"function set_d_visibility(d) {\n"
" for (i = d_min; i <= d_max; i++) {\n"
" var elem = document.getElementById(\"d\"+i.toString());\n"
" if (i == d-2) {\n"
" elem.setAttributeNS(null,\"fill-opacity\", 0.5);\n"
" elem.setAttributeNS(null,\"stroke-opacity\", 0.5);\n"
" elem.setAttributeNS(null,\"visibility\", \"visible\");\n"
" } else if (i == d-1) {\n"
" elem.setAttributeNS(null,\"fill-opacity\", 0.75);\n"
" elem.setAttributeNS(null,\"stroke-opacity\", 0.75);\n"
" elem.setAttributeNS(null,\"visibility\", \"visible\");\n"
" } else if (i == d) {\n"
" elem.setAttributeNS(null,\"visibility\", \"visible\");\n"
" } else {\n"
" elem.setAttributeNS(null,\"fill-opacity\", 1);\n"
" elem.setAttributeNS(null,\"stroke-opacity\", 1);\n"
" elem.setAttributeNS(null,\"visibility\", \"hidden\");\n"
" }\n"
" var txtelem = document.getElementById(\"d\"+i.toString()+\"text\");\n"
" if (i == d && txtelem)\n"
" txtelem.setAttributeNS(null,\"visibility\", \"visible\");\n"
" else\n"
" txtelem.setAttributeNS(null,\"visibility\", \"hidden\");\n"
" }\n"
"}\n"
"\n"
"function do_prev() {\n"
" if (curr_d > d_min)\n"
" curr_d--;\n"
" set_d_visibility(curr_d);\n"
"}\n"
"function do_next() {\n"
" if (curr_d < d_max)\n"
" curr_d++;\n"
" set_d_visibility(curr_d);\n"
"}\n"
" ]]></script>\n"
,[SxLen*Dx+2*XOffs+10, SyLen*Dy+2*YOffs, DMax]),
io:format(Fd,
" <g id=\"nav\">\n", []),
io:format(Fd,
" <path d=\"M ~w,~w v ~w l ~w,~w z\"\n"
" fill=\"#112233\" stroke=\"none\"\n"
" fill-opacity=\"0.75\"\n"
" id=\"prev\"\n"
" onmouseover=\"lightup('prev');\"\n"
" onmouseout=\"lightdown('prev');\"\n"
" onmousedown=\"do_prev();\"\n"
" />\n"
, [round(Dx/4),0,
Dy,
-round(Dx/2), -round(Dy/2)]),
io:format(Fd,
" <path d=\"M ~w,~w v ~w l ~w,~w z\"\n"
" fill=\"#112233\" stroke=\"none\"\n"
" fill-opacity=\"0.75\"\n"
" id=\"next\"\n"
" onmouseover=\"lightup('next')\"\n"
" onmouseout=\"lightdown('next')\"\n"
" onmousedown=\"do_next()\"\n"
" />\n"
, [SxLen*Dx+2*XOffs-Dx,0,
Dy,
round(Dx/2), -round(Dy/2)]),
io:format(Fd,
" </g>\n", []),
BoxLineStyle = o([{class,border}]),
GridLineStyle = o([{class,grid}]),
PathLineStyle = o([{class,path}]),
EndPtStyle = o([{class,endpt}]),
FinalPathLineStyle = o([{class,fpath}]),
FinalEndPtStyle = o([{class,fendpt}]),
io:format(Fd, " <g id=\"gridlayer1\">\n", []),
%% Grid lines...
lists:foreach(fun(X) -> io:format(Fd,
" <path d=\"M ~w,~w v ~w\"\n ~s />\n"
,[X*Dx+XOffs, YOffs, SyLen*Dy,
GridLineStyle])
end,
lists:seq(1,SxLen)),
lists:foreach(fun(Y) -> io:format(Fd,
" <path d=\"M ~w,~w h ~w\"\n ~s />\n"
,[XOffs, Y*Dy+YOffs, SxLen*Dx,
GridLineStyle])
end,
lists:seq(1,SyLen)),
%% Box around
io:format(
Fd,
" <path d=\"M ~w,~w v ~w h ~w v -~w z\" ~s />\n"
,[XOffs, YOffs, SyLen*Dy, SxLen*Dx, SyLen*Dy, BoxLineStyle]),
%% Symbols for each X/Y
lists:foreach(
fun({X,C}) ->
io:format(
Fd,
" <text x=\"~w\" y=\"~.2f\"\n"
" font-size=\"8\" text-anchor=\"middle\">~c</text>\n",
[XOffs+Dx*X+round(Dx/2), YOffs-YOffs/4, C])
end,
index0seq(Sx)),
lists:foreach(
fun({Y,C}) ->
io:format(
Fd,
" <text x=\"~w\" y=\"~.2f\"\n"
" font-size=\"8\" text-anchor=\"middle\">~c</text>\n",
[XOffs-Dx/2, YOffs+Dy*(Y+1)-YOffs/4, C])
end,
index0seq(Sy)),
io:format(Fd, " </g>\n", []),
#fdinfo{fd = Fd,
xoffs = XOffs,
yoffs = YOffs,
dx = Dx,
dy = Dy,
pathlinestyle = PathLineStyle,
endpointstyle = EndPtStyle,
final_pathlinestyle = FinalPathLineStyle,
final_endpointstyle = FinalEndPtStyle}.
index0seq([]) -> [];
index0seq(L) -> lists:zip(lists:seq(0,length(L)-1), L).
print_svg_d(#fdinfo{fd=Fd, xoffs=XOffs,yoffs=YOffs, dx=Dx}, D) ->
io:format(Fd,
" <g id=\"d~wtext\" visibility=\"~s\">\n"
" <text x=\"~w\" y=\"~.2f\" font-size=\"8\"\n"
" text-anchor=\"end\"\n"
" fill=\"#0000cc\">~w</text>\n"
" </g>\n"
,[D, if D == 0 -> "visible"; true -> "hidden" end,
XOffs-Dx*0.25, YOffs-YOffs/4, D]),
io:format(Fd,
" <g id=\"d~w\" visibility=\"~s\">\n"
,[D, if D == 0 -> "visible"; true -> "hidden" end]).
print_svg_d_closed(#fdinfo{fd=Fd}) ->
io:format(Fd, " </g>\n", []).
print_svg_dpath(FdInfo, {_X, _Y, _Sx, _Sy, RSteps}=_DPath) ->
#fdinfo{pathlinestyle = PathLineStyle,
endpointstyle = EndPtStyle} = FdInfo,
print_svg_dpath_2(FdInfo, RSteps, PathLineStyle, EndPtStyle).
print_svg_dpath_2(FdInfo, RSteps, PathLineStyle, EndPtStyle) ->
#fdinfo{fd = Fd,
xoffs = XOffs,
yoffs = YOffs,
dx = Dx,
dy = Dy} = FdInfo,
io:format(Fd, " <path d=\"M ~w,~w ", [XOffs, YOffs]),
{X,Y} = lists:foldl(
fun({Dir, _C}, {X0,Y0}) ->
%% X,Y seems to be reversed below [1]
%% but they are not. This is because of
%% how x,y are defined (removing a char
%% from Sx inserting a char from Sy,
%% respectively).
{X1,Y1} = if Dir == e -> {1,1};
Dir == x -> {0,1}; %% [1] here...
Dir == y -> {1,0} %% ... and here
end,
io:format(Fd, " l ~w,~w", [X1*Dx, Y1*Dx]),
{X0+X1, Y0+Y1}
end,
{0,0},
lists:reverse(RSteps)),
io:format(Fd, "\"\n ~s\n />\n", [PathLineStyle]),
io:format(Fd,
" <circle cx=\"~w\" cy=\"~w\" r=\"~.2f\"\n"
" ~s />\n"
,[XOffs+X*Dx,YOffs+Y*Dy, Dx/4, EndPtStyle]).
print_final_edit_script(FdInfo, EditScript) ->
#fdinfo{final_pathlinestyle = PathLineStyle,
final_endpointstyle = EndPtStyle} = FdInfo,
RSteps1 = lists:append(
lists:map(fun({ins,Elems}) -> [{x,E} || E <- Elems];
({del,Elems}) -> [{y,E} || E <- Elems];
({eq,Elems}) -> [{e,E} || E <- Elems]
end,
EditScript)),
RSteps2 = lists:reverse(RSteps1),
print_svg_dpath_2(FdInfo, RSteps2, PathLineStyle, EndPtStyle).
print_svg_dmax(#fdinfo{fd=Fd}, D) ->
io:format(
Fd,
" <script><![CDATA[\n"
"var d_max=~w;\n"
" ]]></script>\n"
,[D]).
close_svg_file(#fdinfo{fd=Fd}) ->
%% Trailer
io:format(
Fd,
" </g>\n"
"</svg>\n"
,[]),
file:close(Fd),
ok.
o(L) -> case o2(L) of
" "++Rest -> Rest;
Os -> Os
end.
o2(L) ->
lists:flatten(
lists:map(
fun({K,V}) when is_atom(V) -> [" ",a2s(K), "=\"", a2s(V), "\""];
({K,V}) when is_integer(V) -> [" ",a2s(K), "=\"", i2s(V), "\""];
({K,V}) when is_list(V) -> [" ",a2s(K), "=\"", V, "\""]
end,
L)).
a2s(A) -> atom_to_list(A).
i2s(I) -> integer_to_list(I).