lib/graph: Fix `to_dot` that could produce invalid dot when making arcs between inval...

[nit.git] / lib / graphs / digraph.nit

diff --git a/lib/graphs/digraph.nit b/lib/graphs/digraph.nit
index bc9a8af..65e0162 100644 (file)
--- a/lib/graphs/digraph.nit
+++ b/lib/graphs/digraph.nit
@@ -369,15 +369,17 @@ interface Digraph[V: Object]
        fun to_dot: String
        do
                var s = "digraph \{\n"
+               var id_set = new HashMap[V, Int]
                # Writing the vertices
-               for u in vertices_iterator do
-                       s += "   \"{u.to_s.escape_to_dot}\" "
+               for u in vertices_iterator, i in [0 .. vertices.length[ do
+                       id_set[u] = i
+                       s += "   \"{i}\" "
                        s += "[label=\"{u.to_s.escape_to_dot}\"];\n"
                end
                # Writing the arcs
                for arc in arcs do
-                       s += "   {arc[0].to_s.escape_to_dot} "
-                       s += "-> {arc[1].to_s.escape_to_dot};"
+                       s += "   {id_set[arc[0]]} "
+                       s += "-> {id_set[arc[1]]};"
                end
                s += "\}"
                return s