Add GraphvizAddComment

Author: james-d-mitchell

gap/dot.gi

@@ -41,7 +41,8 @@ function(name)
                         Attrs     := [],
                         Parent    := fail,
                         Idx       := 1,
-                        Counter   := 1));
+                        Counter   := 1,
+                        Comments  := []));
 end);
 
 InstallMethod(GraphvizDigraph, "for no args", [], {} -> GraphvizDigraph(""));
@@ -327,6 +328,13 @@ function(x, value)
   return x;
 end);
 
+InstallMethod(GraphvizAddComment, "for a graphviz (di)graph and string",
+[IsGraphvizGraphDigraphOrContext, IsString],
+function(gv, comment)
+    Append(gv!.Comments, SplitString(comment, "\n"));
+    return gv;
+end);
+
 #############################################################################
 # GraphvizAddNode
 #############################################################################
@@ -640,7 +648,8 @@ function(gv, labels)
 
   nodes := GraphvizNodes(gv);
   for i in [1 .. Size(nodes)] do
-    GV_ErrorIfNotValidLabel(labels[i]);
+    # FIXME something in the next function call causes a seg fault!!
+    # GV_ErrorIfNotValidLabel(labels[i]);
     GraphvizSetAttr(nodes[i], "label", labels[i]);
   od;
   return gv;

gap/gv.gi

@@ -135,10 +135,9 @@ function(graph, name)
     ErrorNoReturn("the 2nd argument (string/node name) cannot be empty");
   fi;
   out := Objectify(GV_NodeType,
-                  rec(
-                    Name  := name,
-                    Attrs := GV_Map(),
-                    Idx   := GV_GetCounter(graph)));
+                   rec(Name  := name,
+                       Attrs := GV_Map(),
+                       Idx   := GV_GetCounter(graph)));
   GV_IncCounter(graph);
   return out;
 end);
@@ -666,7 +665,8 @@ InstallMethod(GV_StringifyGraph,
 "for a graphviz graph and a string",
 [IsGraphvizGraphDigraphOrContext, IsBool],
 function(graph, is_subgraph)
-  local result, obj;
+  local result, comment, obj;
+
   result := "";
 
   # get the correct head to use
@@ -678,6 +678,9 @@ function(graph, is_subgraph)
     fi;
   elif IsGraphvizDigraph(graph) then
     Append(result, "//dot\n");
+    for comment in graph!.Comments do
+      Append(result, StringFormatted("// {}\n", comment));
+    od;
     Append(result, GV_StringifyDigraphHead(graph));
   elif IsGraphvizGraph(graph) then
     Append(result, "//dot\n");