Properly indent the generated DOT

gap/gv.gi

@@ -239,6 +239,18 @@ function(graph)
   return graph;
 end);
 
+BindGlobal("GV_Indent", lvl -> ListWithIdenticalEntries(2 * lvl, ' '));
+
+BindGlobal("GV_Depth", function(gv)
+  local depth;
+  depth := 0;
+  while GV_GetParent(gv) <> fail do
+    gv := GV_GetParent(gv);
+    depth := depth + 1;
+  od;
+  return depth;
+end);
+
 InstallMethod(GV_AddNode,
 "for a graphviz graph and node",
 [IsGraphvizGraphDigraphOrContext, IsGraphvizNode],
@@ -272,11 +284,17 @@ graph -> StringFormatted("digraph {} {{\n", GraphvizName(graph)));
 
 # @ Return DOT subgraph head line.
 BindGlobal("GV_StringifySubgraphHead",
-graph -> StringFormatted("subgraph {} {{\n", GraphvizName(graph)));
+gv -> StringFormatted("{}subgraph {} {{\n", GV_Indent(GV_Depth(gv)), GraphvizName(gv)));
 
 # @ Return DOT subgraph head line.
 BindGlobal("GV_StringifyContextHead",
-graph -> StringFormatted("// {} context \n{{\n", GraphvizName(graph)));
+function(gv)
+  local indent;
+  indent := GV_Indent(GV_Depth(gv));
+  return StringFormatted("{1}{{\n{1}  // context \"{2}\" \n",
+                         indent,
+                         GraphvizName(gv));
+end);
 
 BindGlobal("GV_StringifyNodeName",
 function(node)
@@ -289,13 +307,7 @@ function(node)
       and not StartsWith(name, "\"") then
     old  := name;
     name := StringFormatted("\"{}\"", name);
-    Info(InfoWarning,
-         1,
-         "invalid node name ",
-         old,
-         " using ",
-         name,
-         " instead");
+    Info(InfoWarning, 1, "invalid node name ", old, " using ", name, " instead");
   fi;
   return name;
 end);
@@ -339,7 +351,10 @@ function(node)
   local name, attrs;
   name  := GV_StringifyNodeName(node);
   attrs := GraphvizAttrs(node);
-  return StringFormatted("\t{}{}\n", name, GV_StringifyAttrList(attrs));
+  return StringFormatted("{}{}{}\n",
+                         GV_Indent(GV_Depth(node)),
+                         name,
+                         GV_StringifyAttrList(attrs));
 end);
 
 # @ Return DOT graph edge statement line.
@@ -353,7 +368,8 @@ function(edge, edge_str)
   attrs := GraphvizAttrs(edge);
 
   # handle : syntax
-  return StringFormatted("\t{} {} {}{}\n",
+  return StringFormatted("{}{} {} {}{}\n",
+                         GV_Indent(GV_Depth(edge)),
                          head,
                          edge_str,
                          tail,
@@ -413,7 +429,11 @@ function(graph, is_subgraph)
   for type in ["graph", "node", "edge"] do
     record := GraphvizAttrs(graph).(type);
     if Length(RecNames(record)) > 0 then
-      Append(result, StringFormatted("{} {}\n", type, GV_StringifyAttrList(record)));
+      Append(result,
+        StringFormatted("{}{}{}\n",
+                        GV_Indent(GV_Depth(graph) + 1),
+                        type,
+                        GV_StringifyAttrList(record)));
     fi;
   od;
 
@@ -432,7 +452,10 @@ function(graph, is_subgraph)
     fi;
   od;
 
-  Append(result, "}\n");
+  Append(result, StringFormatted("{}}}", GV_Indent(GV_Depth(graph))));
+  if GV_Depth(graph) > 0 then
+    Append(result, "\n");
+  fi;
   return result;
 end);
 

tst/dot.tst

@@ -38,8 +38,11 @@ rec( edge := rec(  ),
 gap> g := GraphvizGraph();;
 gap> n := GraphvizAddNode(g, "test");;
 gap> GraphvizSetAttrs(n, rec(color := "red", label := "lab"));;
-gap> AsString(g);
-"//dot\ngraph  {\n\ttest [color=\"red\", label=\"lab\"]\n}\n"
+gap> Print(AsString(g), "\n");
+//dot
+graph  {
+  test [color="red", label="lab"]
+}
 gap> GraphvizRemoveNode(g, "banana");
 Error, the 2nd argument (node name string) "banana" is not a node of the 1st a\
 rgument (a graphviz (di)graph/context)
@@ -52,9 +55,13 @@ gap> GraphvizSetAttrs(a, rec(color := "blue"));;
 gap> GraphvizSetAttrs(b, rec(color := "red"));;
 gap> e := GraphvizAddEdge(g, a, b);;
 gap> GraphvizSetAttrs(e, rec(color := "green"));;
-gap> AsString(g);
-"//dot\ndigraph  {\n\ta [color=\"blue\"]\n\tb [color=\"red\"]\n\ta -> b [color\
-=\"green\"]\n}\n"
+gap> Print(AsString(g), "\n");
+//dot
+digraph  {
+  a [color="blue"]
+  b [color="red"]
+  a -> b [color="green"]
+}
 
 # Test stringify with edge (graph)
 gap> g := GraphvizGraph();;
@@ -64,14 +71,20 @@ gap> GraphvizSetAttrs(a, rec(color := "blue"));;
 gap> GraphvizSetAttrs(b, rec(color := "red"));;
 gap> e := GraphvizAddEdge(g, a, b);;
 gap> GraphvizSetAttrs(e, rec(color := "green"));;
-gap> AsString(g);
-"//dot\ngraph  {\n\ta [color=\"blue\"]\n\tb [color=\"red\"]\n\ta -- b [color=\
-\"green\"]\n}\n"
+gap> Print(AsString(g), "\n");
+//dot
+graph  {
+  a [color="blue"]
+  b [color="red"]
+  a -- b [color="green"]
+}
 
 # Test stringify empty
 gap> g := GraphvizGraph();;
-gap> AsString(g);
-"//dot\ngraph  {\n}\n"
+gap> Print(AsString(g), "\n");
+//dot
+graph  {
+}
 
 # Test unknown attributes (node)
 gap> g := GraphvizGraph();;
@@ -88,25 +101,41 @@ gap> GraphvizSetAttr(g, "test", "false");
 gap> g := GraphvizGraph();;
 gap> n := GraphvizAddNode(g, "node");;
 gap> GraphvizSetAttr(n, "label", ">>hello");;
-gap> AsString(g);
-"//dot\ngraph  {\n\tnode [label=\">>hello\"]\n}\n"
+gap> Print(AsString(g), "\n");
+//dot
+graph  {
+  node [label=">>hello"]
+}
 gap> g := GraphvizGraph();;
 gap> n := GraphvizAddNode(g, "node");;
 gap> GraphvizSetAttr(n, "label", "before>>hello");;
-gap> AsString(g);
-"//dot\ngraph  {\n\tnode [label=\"before>>hello\"]\n}\n"
+gap> Print(AsString(g), "\n");
+//dot
+graph  {
+  node [label="before>>hello"]
+}
 
 # Test strngifying labels with ">>" inside (edge attrs)
 gap> g := GraphvizGraph();;
 gap> e := GraphvizAddEdge(g, "a", "b");;
 gap> GraphvizSetAttr(e, "label", ">>hello");;
-gap> AsString(g);
-"//dot\ngraph  {\n\ta\n\tb\n\ta -- b [label=\">>hello\"]\n}\n"
+gap> Print(AsString(g), "\n");
+//dot
+graph  {
+  a
+  b
+  a -- b [label=">>hello"]
+}
 gap> g := GraphvizGraph();;
 gap> e := GraphvizAddEdge(g, "a", "b");;
 gap> GraphvizSetAttr(e, "label", "before>>hello");;
-gap> AsString(g);
-"//dot\ngraph  {\n\ta\n\tb\n\ta -- b [label=\"before>>hello\"]\n}\n"
+gap> Print(AsString(g), "\n");
+//dot
+graph  {
+  a
+  b
+  a -- b [label="before>>hello"]
+}
 
 # Test GraphvizSetNodeLabels
 gap> gv := GraphvizGraph("xxx");
@@ -119,21 +148,21 @@ gap> GraphvizAddNode(gv, 3);
 <graphviz node "3">
 gap> GraphvizSetNodeLabels(gv, ["i", "ii", "iii"]);
 <graphviz graph "xxx" with 3 nodes and 0 edges>
-gap> Print(AsString(gv));
+gap> Print(AsString(gv), "\n");
 //dot
 graph xxx {
-	1 [label="i"]
-	2 [label="ii"]
-	3 [label="iii"]
+  1 [label="i"]
+  2 [label="ii"]
+  3 [label="iii"]
 }
 gap> GraphvizSetNodeLabels(gv, ["a", "b", "c"]);
 <graphviz graph "xxx" with 3 nodes and 0 edges>
-gap> Print(AsString(gv));
+gap> Print(AsString(gv), "\n");
 //dot
 graph xxx {
-	1 [label="a"]
-	2 [label="b"]
-	3 [label="c"]
+  1 [label="a"]
+  2 [label="b"]
+  3 [label="c"]
 }
 gap> GraphvizSetNodeLabels(gv, ["i", "ii"]);
 Error, the 2nd argument (list of node labels) has incorrect length, expected 3\
@@ -157,30 +186,30 @@ Error, invalid color "i" (list (string)), valid colors are RGB values or names\
 .html
 gap> GraphvizSetNodeColors(gv, ["red", "green", "blue"]);
 <graphviz graph "xxx" with 3 nodes and 0 edges>
-gap> Print(AsString(gv));
+gap> Print(AsString(gv), "\n");
 //dot
 graph xxx {
-	1 [color="red", style="filled"]
-	2 [color="green", style="filled"]
-	3 [color="blue", style="filled"]
+  1 [color="red", style="filled"]
+  2 [color="green", style="filled"]
+  3 [color="blue", style="filled"]
 }
 gap> GraphvizSetNodeColors(gv, ["red", "#00FF00", "blue"]);
 <graphviz graph "xxx" with 3 nodes and 0 edges>
-gap> Print(AsString(gv));
+gap> Print(AsString(gv), "\n");
 //dot
 graph xxx {
-	1 [color="red", style="filled"]
-	2 [color="#00FF00", style="filled"]
-	3 [color="blue", style="filled"]
+  1 [color="red", style="filled"]
+  2 [color="#00FF00", style="filled"]
+  3 [color="blue", style="filled"]
 }
 gap> GraphvizSetNodeColors(gv, ["#FF0000", "#00FF00", "#0000FF"]);
 <graphviz graph "xxx" with 3 nodes and 0 edges>
-gap> Print(AsString(gv));
+gap> Print(AsString(gv), "\n");
 //dot
 graph xxx {
-	1 [color="#FF0000", style="filled"]
-	2 [color="#00FF00", style="filled"]
-	3 [color="#0000FF", style="filled"]
+  1 [color="#FF0000", style="filled"]
+  2 [color="#00FF00", style="filled"]
+  3 [color="#0000FF", style="filled"]
 }
 gap> GraphvizSetNodeColors(gv, ["#FF0000", "#00FF00", "#0000FG"]);
 Error, invalid color "#0000FG" (list (string)), valid colors are RGB values or\
@@ -206,14 +235,14 @@ gap> n := GraphvizSetAttr(n, "probably not ok", 1);
 gap> Print(AsString(gv : invalidDOT := "unquoted attribute name with spaces"), "\n");
 //dot
 graph xxx {
-	1 [probably not ok="1"]
+  1 [probably not ok="1"]
 }
 gap> GraphvizSetAttr(n, "label", "<<>>");
 <graphviz node "1">
 gap> Print(AsString(gv : invalidDOT := "unquoted attribute name with spaces"), "\n");
 //dot
 graph xxx {
-	1 [label="<<>>", probably not ok="1"]
+  1 [label="<<>>", probably not ok="1"]
 }
 
 # Issue 68
@@ -223,14 +252,25 @@ gap> a := GraphvizAddNode(g, "a");
 <graphviz node "a">
 gap> e := GraphvizAddEdge(g, a, "b");
 <graphviz edge (a, b)>
-gap> GraphvizNodes(g); AsString(g);
+gap> GraphvizNodes(g); Print(AsString(g), "\n");
 rec( a := <graphviz node "a">, b := <graphviz node "b"> )
-"//dot\ndigraph unexpected {\n\ta\n\tb\n\ta -> b\n}\n"
+//dot
+digraph unexpected {
+  a
+  b
+  a -> b
+}
 gap> e := GraphvizAddEdge(g, "b", a);
 <graphviz edge (b, a)>
-gap> GraphvizNodes(g); AsString(g);
+gap> GraphvizNodes(g); Print(AsString(g), "\n");
 rec( a := <graphviz node "a">, b := <graphviz node "b"> )
-"//dot\ndigraph unexpected {\n\ta\n\tb\n\ta -> b\n\tb -> a\n}\n"
+//dot
+digraph unexpected {
+  a
+  b
+  a -> b
+  b -> a
+}
 
 #
 gap> STOP_TEST("graphviz package: dot.tst", 0);