Applications (expr) topology

render/dsl/expression.go

@@ -341,7 +341,11 @@ func cp(dst render.RenderableNodes, src render.RenderableNodes, id string) {
 }
 
 func merge(dst render.RenderableNodes, dstID string, src render.RenderableNodes, srcID string) {
-	dst[dstID] = dst[dstID].Merge(src[srcID])
+	dstNode, ok := dst[dstID]
+	if !ok {
+		dstNode = render.NewRenderableNode(dstID)
+	}
+	dst[dstID] = dstNode.Merge(src[srcID])
 
 	// Every transform that calls merge must call shift at the end, to update
 	// adjacency lists and edge metadatas.

render/dsl/parser.go

@@ -95,7 +95,7 @@ func ParseExpressions(strs ...string) Expressions {
 	for _, str := range strs {
 		expr, err := ParseExpression(str)
 		if err != nil {
-			log.Printf("%s: %v", str, err)
+			log.Printf("%q: %v", str, err)
 			continue
 		}
 		exprs = append(exprs, expr)

render/mapping.go

@@ -31,6 +31,11 @@ const (
 // If the output is empty, the node shall be omitted from the rendered topology.
 type MapFunc func(RenderableNode, report.Networks) RenderableNodes
 
+// MapIdentity returns a perfect identity mapping of the input domain.
+func MapIdentity(n RenderableNode, _ report.Networks) RenderableNodes {
+	return RenderableNodes{n.ID: n}
+}
+
 // MapEndpointIdentity maps an endpoint topology node to a single endpoint
 // renderable node. As it is only ever run on endpoint topology nodes, we
 // expect that certain keys are present.

render/selectors.go

@@ -86,4 +86,15 @@ var (
 	SelectHost = TopologySelector(func(r report.Report) RenderableNodes {
 		return MakeRenderableNodes(r.Host)
 	})
+
+	// SelectAll merges all topologies.
+	SelectAll = TopologySelector(func(r report.Report) RenderableNodes {
+		rns := RenderableNodes{}
+		for _, t := range r.Topologies() {
+			for id, rn := range MakeRenderableNodes(t) {
+				rns[id] = rn
+			}
+		}
+		return rns
+	})
 )