Simplified implementation of node pointers

lib/graph/graph.go

@@ -0,0 +1,85 @@
+package graph
+
+//Node a graph node which can contain Connections to other nodes
+type Node struct {
+	Value       string
+	Incoming []*Node
+	Outgoing []*Node
+}
+
+//SetPointTo sets this Node to point towards the given Node
+func (n *Node) SetPointTo(otherNode *Node) {
+	if n.IsPointingTo(otherNode) == false {
+		n.Outgoing = append(n.Outgoing, otherNode)
+	}
+}
+
+//RemovePointerTo removes pointer to a node (a "child")
+func (n *Node) RemovePointerTo(otherNode *Node) int {
+	i := n.GetIndexOfOut(otherNode)
+	if i != -1 {
+		n.Outgoing = append(n.Outgoing[:i], n.Outgoing[i+1:]...)
+		return i
+	}
+	return -1
+}
+
+//IsPointingTo returns true if this node is pointing to the given argument
+func (n *Node) IsPointingTo(otherNode *Node) bool {
+	if n.GetIndexOfOut(otherNode) != -1 {
+		return true
+	}
+	return false
+}
+
+//Disconnect disconnects two nodes by removing pointers for BOTH
+func (n *Node) Disconnect(otherNode *Node) int {
+	i := n.GetIndexOfOut(otherNode)
+	j := otherNode.GetIndexOfOut(n)
+	if i != -1 && j != -1 {
+		//if n is pointing to otherNode
+		//remove othernode from n.Outgoing, and remove n from otherNode.Outgoing
+		n.Outgoing = append(n.Outgoing[:i], n.Outgoing[i+1:]...)
+		otherNode.Outgoing = append(otherNode.Outgoing[:j], otherNode.Outgoing[j+1:]...)
+		return 1
+	}
+	i = n.GetIndexOfIn(otherNode)
+	j = otherNode.GetIndexOfIn(n)
+	if i!= -1 && j != -1 {
+		//else if otherNode point to n
+		// remove otherNode from n.Incoming, and remove n from otherNode.Incoming
+		n.Incoming = append(n.Incoming[:i], n.Incoming[i+1:]...)
+		otherNode.Incoming = append(otherNode.Incoming[:j], otherNode.Incoming[j+1:]...)
+		return 1
+	}
+	return -1
+}
+
+//DisconnectAll removes all pointer from and to this Node
+func (n *Node) DisconnectAll() {
+	for _, v := range n.Outgoing {
+		n.Disconnect(v)
+	}
+}
+
+
+//GetIndexOfOut gets the index of the specified node that this node points to
+//May alternatively be used to check if n is pointing to otherNode
+func (n *Node) GetIndexOfOut(otherNode *Node) int {
+	for i, v := range n.Outgoing {
+		if v == otherNode { //addresses are compared
+			return i
+		}
+	}
+	return -1
+}
+
+//GetIndexOfIn gets the index of the specified node which points to this node
+func (n *Node) GetIndexOfIn(otherNode *Node) int {
+	for i, v := range n.Incoming {
+		if v == otherNode { //addresses are compared
+			return i
+		}
+	}
+	return -1
+}