graph: don't give values to edges, that can be accomplished by a transformation layer later

graph/graph.go

@@ -34,13 +34,13 @@ func NewValue(V interface{}) Value {
 }
 
 // Edge is a directional edge connecting two values in a Graph, the Tail and the
-// Head. An Edge may also contain a value of its own.
+// Head.
 type Edge struct {
-	Tail, Val, Head Value
+	Tail, Head Value
 }
 
 func (e Edge) id() string {
-	return fmt.Sprintf("%q-%q->%q", e.Tail, e.Val, e.Head)
+	return fmt.Sprintf("%q->%q", e.Tail, e.Head)
 }
 
 // an edgeIndex maps valueIDs to a set of edgeIDs. Graph keeps two edgeIndex's,

graph/graph_test.go

@@ -44,21 +44,13 @@ func TestGraph(t *T) {
 				}
 			} else if i == 1 {
 				// delete edge which isn't there
-				p.del = Edge{Tail: strV("z"), Val: strV("z"), Head: strV("z")}
+				p.del = Edge{Tail: strV("z"), Head: strV("z")}
 			} else if i <= 5 {
 				// add probably new edge
-				p.add = Edge{
-					Tail: strV(mrand.Hex(1)),
-					Val:  strV(mrand.Hex(1)),
-					Head: strV(mrand.Hex(1)),
-				}
+				p.add = Edge{Tail: strV(mrand.Hex(1)), Head: strV(mrand.Hex(1))}
 			} else {
 				// probably del edge
-				p.del = Edge{
-					Tail: strV(mrand.Hex(1)),
-					Val:  strV(mrand.Hex(1)),
-					Head: strV(mrand.Hex(1)),
-				}
+				p.del = Edge{Tail: strV(mrand.Hex(1)), Head: strV(mrand.Hex(1))}
 			}
 			return mchk.Action{Params: p}
 		},
@@ -146,11 +138,7 @@ func TestSubGraphAndEqual(t *T) {
 		Next: func(ss mchk.State) mchk.Action {
 			i := mrand.Intn(10)
 			p := params{
-				e: Edge{
-					Tail: strV(mrand.Hex(1)),
-					Val:  strV(mrand.Hex(8)),
-					Head: strV(mrand.Hex(1)),
-				},
+				e:    Edge{Tail: strV(mrand.Hex(4)), Head: strV(mrand.Hex(4))},
 				add1: i != 0,
 				add2: i != 1,
 			}