Add DOT attributes to multi.DirectedGraph Lines

[miller]

I'm trying to un-marhsal DOT input into a multi.DirectedGraph. Notice that the `dir` attribute determines the direction of the edge. If the value of `dir` is `both`, then I need to add a line (from, to) and (to, from). 

I'm trying to use `dot.UnmarshalMulti()` to un-marshal and I'm able to wrap the multi.DirectedGraph such that I can print out the attributes of edges when un-marshalling but not able to set any of the attributes on the line, `attrs` is always empty. This is my second project with Go and first post in this forum so any help is appreciated.

type dotMultiGraph struct {

*multi.DirectedGraph

}

func newDotMultiGraph() *dotMultiGraph {

return &dotMultiGraph{DirectedGraph: multi.NewDirectedGraph()}

}

func (g *dotMultiGraph) AddEdge(from, to graph.Node) graph.Line {

e := &dotLine{Line: g.DirectedGraph.NewLine(from, to), attrs: make(map[string]string)}

return e

}

func (g *dotMultiGraph) NewLine(from, to graph.Node) graph.Line {

line := g.DirectedGraph.NewLine(from, to)

dotLine := &dotLine{Line: line, attrs: make(map[string]string)}

return dotLine

}

func (g *dotMultiGraph) SetLine(e graph.Line) {

fmt.Printf("yoo: %+v\n", e.(*dotLine)) // this is where I think I would check if dir == both

g.DirectedGraph.SetLine(e.(*dotLine))

}

type dotLine struct {

graph.Line

attrs map[string]string

}

func (e *dotLine) SetAttribute(attr encoding.Attribute) error {

fmt.Printf("attr: %s\n", attr)

e.attrs[attr.Key] = attr.Value

return nil

}

func TestParsingGraphs(t *testing.T) {

ug := `

digraph "graph" {

graph [fontsize=12]

node [fontsize=12]

edge [fontsize=12]

rankdir=TB;

"N0" -> "N1" [uuid = "<Node1, Node0>", color = "#000000", fontcolor = "#000000", style = "solid", label = "edges", dir = "forward"]

"N0" -> "N2" [uuid = "<Node1, Node2>", color = "#000000", fontcolor = "#000000", style = "solid", label = "edges", dir = "both"]

"N2" -> "N1" [uuid = "<Node2, Node0>", color = "#000000", fontcolor = "#000000", style = "solid", label = "edges", dir = "forward"]

"N0" [uuid="Node1", label="Node1", color="#ffd700", fontcolor = "#000000", shape = "box", style = "filled, solid"]

"N1" [uuid="Node0", label="Node0", color="#ffd700", fontcolor = "#000000", shape = "box", style = "filled, solid"]

"N2" [uuid="Node2", label="Node2\n($cyclic_n)", color="#ffd700", fontcolor = "#000000", shape = "box", style = "filled, solid"]

}

`

// g := multi.NewDirectedGraph()

// multi.DirectedGraph

g := newDotMultiGraph()

err := dot.UnmarshalMulti([]byte(ug), g)

if err != nil {

log.Fatalf("failed to unmarshal DOT data: %v", err)

}

// cycles := topo.DirectedCyclesIn(g)

// if len(cycles) == 0 {

// t.Logf("Analysis result: %s\n", ug) // todo: handle command not found

// t.Logf("Cycles: %s", cycles)

// // Print out the nodes and edges

// t.Log("Nodes:")

// for nodes := g.Nodes(); nodes.Next(); {

// node := nodes.Node()

// t.Logf("Node ID: %v\n", node.ID())

// }

t.Log("Edges:")

for edges := g.Edges(); edges.Next(); {

edge := edges.Edge()

// t.Log(edge)

fmt.Printf("%+v\n", g.Lines(edge.From().ID(), edge.To().ID()).Line())

t.Logf("Edge from %v to %v\n", edge.From().ID(), edge.To().ID())

}

data, err := dot.Marshal(g, "Example Graph", "", "\t")

if err != nil {

log.Fatalf("error marshalling graph to DOT: %v", err)

}

t.Log(string(data))

// t.Errorf("Expected cycles to be > 0, found none")

// }

}

[Dan Kortschak]

On Mon, 2024-07-22 at 20:07 -0700, miller wrote:
> I'm trying to un-marhsal DOT input into a multi.DirectedGraph. Notice
> that the `dir` attribute determines the direction of the edge. If the
> value of `dir` is `both`, then I need to add a line (from, to) and
> (to, from). 
>
> I'm trying to use `dot.UnmarshalMulti()` to un-marshal and I'm able
> to wrap the multi.DirectedGraph such that I can print out the
> attributes of edges when un-marshalling but not able to set any of
> the attributes on the line, `attrs` is always empty. This is my
> second project with Go and first post in this forum so any help is
> appreciated.

This does what you want, https://go.dev/play/p/5W8BOzSXmp7. It's not
nice, but you are reaching outside the intended usage of DOT. The
attributes are set after the edge is added to the graph.

Please post plain text.

Dan

[miller]

Thank you sir. In case someone finds it helpful, here[1] is a slightly modified version of the code you sent that I'm using.

[1]: https://go.dev/play/p/GW_dVnGjQTa