Export flow_graph:add_edge/2 for low-level manipulation.

src/flow_graph.erl

@@ -7,7 +7,7 @@
 % Graph construction
 -export([singleton/1, from_list/3]).
 % Graph manipulation
--export([append/2, append/1, get_in/1, get_out/1, out_edges/2]).
+-export([append/2, append/1, get_in/1, get_out/1, out_edges/2, add_edge/2]).
 % Checks for validity
 -export([valid_edge/1, valid_edge_list/1, valid_graph/1]).
 % Branching
@@ -130,9 +130,9 @@ get_out(#flow_graph{out=Out}) -> Out.
 out_edges(#flow_graph{graph=G}, #vertex{ref=R}) ->
     ?DICT:find(R, G).
 
-add_edge(FG = #flow_graph{graph=G}, E = #edge{from=From}) ->
+add_edge(FG = #flow_graph{graph=G}, E = #edge{from=From, to=To}) ->
     Add = fun(Edges) -> [E|Edges] end,
-    FG#flow_graph{graph=?DICT:update(From, Add, [E], G)}.
+    FG#flow_graph{graph=?DICT:update(From, Add, [E], add_vertex(G,To))}.
 
 add_vertex(FG = #flow_graph{graph=G}, V = #vertex{}) ->
     FG#flow_graph{graph=?DICT:update(V, fun(Es)->Es end, [], G)}.