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diff --git a/src/edit_text.erl b/src/edit_text.erl
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+%%%----------------------------------------------------------------------
+%%% File    : edit_text.erl
+%%% Author  : Luke Gorrie <luke@bluetail.com>
+%%% Purpose : Text data structure with markers and undo
+%%% Created :  2 Oct 2001 by Luke Gorrie <luke@bluetail.com>
+%%%----------------------------------------------------------------------
+
+-module(edit_text).
+-author('luke@bluetail.com').
+
+-export([new/0, new/1, replace/4, add_mark/4, move_mark/3, mark_pos/2,
+	 undo/2, cord/1, walk_backward/3, walk_forward/3]).
+
+-record(text, {cord, marks=[], undo=[], running_undo=[]}).
+
+-record(mark,  {name, pos, direction}).
+
+%% ----------------------------------------------------------------------
+%% new
+
+new() ->
+    new(<<>>).
+
+new(BCS) when list(BCS) ->
+    new(cord:new(BCS));
+new(Cord) ->
+    #text{cord=Cord}.
+
+%% ----------------------------------------------------------------------
+%% replace (CBS means Cord, Binary, or String)
+
+replace(Text0 = #text{cord=Cord0,marks=Marks0,undo=Undo0}, CBS, Start, Len) ->
+    Cord1 = cord:replace(Cord0, CBS, Start, Len),
+    Marks1 = update_marks(Marks0, Start, Start+Len, cbs_length(CBS)),
+    Undo1 = [{Cord0, Marks0} | Undo0],
+    %% FIXME: maybe better to chain undo through states (i.e. just
+    %% know about previous state, which knows about previous state,
+    %% ...) - if that plays nicely with "running undo"
+    Text0#text{cord=Cord1, marks=Marks1, undo=Undo1, running_undo=[]}.
+
+cbs_length(L) when list(L)   -> length(L);
+cbs_length(B) when binary(B) -> size(B);
+cbs_length(C)                -> cord:cord_size(C).
+
+update_marks(Marks, Start, End, Len) ->
+    [update_mark(Mark,Start,End,Len) || Mark <- Marks].
+
+%% Inside the replaced region (includes being on an inserted character)
+update_mark(Mark, Start, End, Len)
+  when Mark#mark.pos >= Start,
+       Mark#mark.pos < End;
+       Mark#mark.pos == Start ->
+    case Mark#mark.direction of
+	forward ->
+	    Mark#mark{pos=Start+Len};
+	backward ->
+	    Mark#mark{pos=Start}
+    end;
+%% After the replaced region
+update_mark(Mark, Start, End, Len) when Mark#mark.pos >= End ->
+    %% We move forward by the length-delta
+    Mark#mark{pos = Mark#mark.pos - (End - Start) + Len};
+%% Before the replaced region
+update_mark(Mark, _Start, _End, _Len) ->
+    Mark.
+
+%% ----------------------------------------------------------------------
+%% add_mark
+
+add_mark(Text = #text{marks=Marks0}, Name, Pos, Direction) ->
+    Mark = #mark{name=Name, pos=Pos, direction=Direction},
+    Text#text{marks=[Mark|Marks0]}.
+
+%% ----------------------------------------------------------------------
+%% move_mark
+
+move_mark(Text0, Name, Pos) ->
+    {Front, [M | Back]} =
+	lists:splitwith(fun(X) -> X#mark.name /= Name end,
+			Text0#text.marks),
+    NewMarks = Front ++ [M#mark{pos=Pos} | Back],
+    Text0#text{marks=NewMarks}.
+
+%% ----------------------------------------------------------------------
+%% mark_pos
+
+mark_pos(#text{marks=Marks}, Name) ->
+    {found, Mark} = find(fun(M) -> M#mark.name == Name end, Marks),
+    Mark#mark.pos.
+
+find(Pred, []) ->
+    not_found;
+find(Pred, [H|T]) ->
+    case Pred(H) of
+	true ->
+	    {found, H};
+	false ->
+	    find(Pred, T)
+    end.
+
+%% ----------------------------------------------------------------------
+%% walk_backward
+
+walk_backward(Text = #text{cord=Cord}, Fun, Pos) ->
+    Size = cord:cord_size(Cord),
+    if Pos == Size + 1 ->
+	    case Fun(not_there) of
+		{more, FNext} ->
+		    walk_backward(Text, FNext, Pos-1);
+		{result, R} ->
+		    R
+	    end;
+       true ->
+	    cord:walk(Cord, Pos, backward, Fun)
+    end.
+
+%% ----------------------------------------------------------------------
+%% walk_forward
+
+walk_forward(#text{cord=Cord}, Fun, Pos) ->
+    cord:walk(Cord, Pos, forward, Fun).
+
+%% ----------------------------------------------------------------------
+%% undo
+
+undo(Text0 = #text{undo=Undo, running_undo=Running}, Continuing) ->
+    Text1 = case Continuing of
+		true ->
+		    Text0;
+		false ->
+		    Text0#text{running_undo=Undo}
+	    end,
+    case Running of
+	%% Nothing to undo - recycle redo list
+	[] ->
+	    Text1#text{running_undo=Undo};
+	[{UndoCord, UndoMarks}|Undos] ->
+	    Text1#text{cord=UndoCord,
+		       marks=UndoMarks,
+		       undo=[{Text0#text.cord, Text0#text.marks} | Undo],
+		       running_undo=Undos}
+    end.
+
+%% ----------------------------------------------------------------------
+%% cord
+
+cord(#text{cord=Cord}) -> Cord.
+