Update docs for Graph and Node

Updates godoc and adds Add() method instead of using
append on the private slice.

Signed-off-by: Alex Ellis (OpenFaaS Ltd) <alexellis2@gmail.com>

pkg/depends_on.go

@@ -1,6 +1,8 @@
 package pkg
 
-import "fmt"
+import (
+	"log"
+)
 
 func buildInstallOrder(svcs []Service) []string {
 	graph := Graph{nodes: []*Node{}}
@@ -24,10 +26,10 @@ func buildInstallOrder(svcs []Service) []string {
 		resolve(g, resolved, unresolved)
 	}
 
-	fmt.Printf("Installation order:\n")
+	log.Printf("Start-up order:\n")
 	order := []string{}
 	for _, node := range resolved.nodes {
-		fmt.Printf("- %s\n", node.Name)
+		log.Printf("- %s\n", node.Name)
 		order = append(order, node.Name)
 	}
 

pkg/graph.go

@@ -2,12 +2,57 @@ package pkg
 
 import "log"
 
+// Node represents a node in a Graph with
+// 0 to many edges
+type Node struct {
+	Name  string
+	Edges []*Node
+}
+
+// Graph is a collection of nodes
+type Graph struct {
+	nodes []*Node
+}
+
+// Contains returns true if the target Node is found
+// in its list
+func (g *Graph) Contains(target *Node) bool {
+	for _, g := range g.nodes {
+		if g.Name == target.Name {
+			return true
+		}
+	}
+
+	return false
+}
+
+// Add places a Node into the current Graph
+func (g *Graph) Add(target *Node) {
+	g.nodes = append(g.nodes, target)
+}
+
+// Remove deletes a target Node reference from the
+// list of nodes in the graph
+func (g *Graph) Remove(target *Node) {
+	var found *int
+	for i, n := range g.nodes {
+		if n == target {
+			found = &i
+			break
+		}
+	}
+
+	if found != nil {
+		g.nodes = append(g.nodes[:*found], g.nodes[*found+1:]...)
+	}
+}
+
 // resolve finds the order of dependencies for a graph
 // of nodes.
 // Inspired by algorithm from
 // https://www.electricmonk.nl/log/2008/08/07/dependency-resolving-algorithm/
 func resolve(node *Node, resolved, unresolved *Graph) {
-	unresolved.nodes = append(unresolved.nodes, node)
+	unresolved.Add(node)
 
 	for _, edge := range node.Edges {
 
@@ -24,46 +69,6 @@ func resolve(node *Node, resolved, unresolved *Graph) {
 		}
 	}
 
-	resolved.nodes = append(resolved.nodes, node)
-
+	resolved.Add(node)
 	unresolved.Remove(node)
 }
-
-func newNode(name string, edges []*Node) *Node {
-	return &Node{
-		Name:  name,
-		Edges: edges,
-	}
-}
-
-type Node struct {
-	Name  string
-	Edges []*Node
-}
-
-type Graph struct {
-	nodes []*Node
-}
-
-func (g *Graph) Contains(target *Node) bool {
-	for _, g := range g.nodes {
-		if g.Name == target.Name {
-			return true
-		}
-	}
-
-	return false
-}
-func (g *Graph) Remove(target *Node) {
-	var found *int
-	for i, n := range g.nodes {
-		if n == target {
-			found = &i
-			break
-		}
-	}
-
-	if found != nil {
-		g.nodes = append(g.nodes[:*found], g.nodes[*found+1:]...)
-	}
-}