d2ir: Add label filter exception for edges too

d2ir/compile.go

@@ -561,7 +561,21 @@ func (c *compiler) ampersandFilter(refctx *RefContext) bool {
 		kp := refctx.Key.Key.Copy()
 		kp.Path = kp.Path[:len(kp.Path)-1]
 		if len(kp.Path) == 0 {
-			fa = append(fa, ParentField(refctx.ScopeMap))
+			n := refctx.ScopeMap.Parent()
+			switch n := n.(type) {
+			case *Field:
+				fa = append(fa, n)
+			case *Edge:
+				if n.Primary_ == nil {
+					if refctx.Key.Value.ScalarBox().Unbox().ScalarString() == "" {
+						return true
+					}
+					return false
+				}
+				if n.Primary_.Value.ScalarString() != refctx.Key.Value.ScalarBox().Unbox().ScalarString() {
+					return false
+				}
+			}
 		} else {
 			fa, err = refctx.ScopeMap.EnsureField(kp, refctx, false, c)
 			if err != nil {

d2ir/filter_test.go

@@ -97,12 +97,13 @@ x -> y
 			},
 		},
 		{
-			name: "id-filter",
+			name: "label-filter",
 			run: func(t testing.TB) {
 				m, err := compile(t, `
 x
 y
 p: p
+a -> z: delta
 
 *.style.opacity: 0.1
 *: {
@@ -113,12 +114,19 @@ p: p
   &label: p
   style.opacity: 0.5
 }
+(* -> *)[*]: {
+	&label: delta
+	target-arrowhead.shape: diamond
+}
 `)
 				assert.Success(t, err)
-				assertQuery(t, m, 9, 0, nil, "")
+				assertQuery(t, m, 17, 1, nil, "")
 				assertQuery(t, m, 0, 0, 1, "x.style.opacity")
 				assertQuery(t, m, 0, 0, 0.1, "y.style.opacity")
 				assertQuery(t, m, 0, 0, 0.5, "p.style.opacity")
+				assertQuery(t, m, 0, 0, 0.1, "a.style.opacity")
+				assertQuery(t, m, 0, 0, 0.1, "z.style.opacity")
+				assertQuery(t, m, 0, 0, "diamond", "(a -> z).target-arrowhead.shape")
 			},
 		},
 	}