Data Structures and Algorithm Analysis - Computer Science at ...

Sec. 5.3 Binary Tree Node Implementations 157/** Base class for expression tree nodes */public interface VarBinNode {public boolean isLeaf(); // All subclasses must implement}/** Leaf node */class VarLeafNode implements VarBinNode {private String operand;// Operand valuepublic VarLeafNode(String val) { operand = val; }public boolean isLeaf() { return true; }public String value() { return operand; }};/** Internal node */class VarIntlNode implements VarBinNode {private VarBinNode left;private VarBinNode right;private Character operator;}public VarIntlNode(Character op,VarBinNode l, VarBinNode r){ operator = op; left = l; right = r; }public boolean isLeaf() { return false; }public VarBinNode leftchild() { return left; }public VarBinNode rightchild() { return right; }public Character value() { return operator; }// Left child// Right child// Operator value/** Preorder traversal */public static void traverse(VarBinNode rt) {if (rt == null) return;// Nothing to visitif (rt.isLeaf())// Process leaf nodeVisit.VisitLeafNode(((VarLeafNode)rt).value());else {// Process internal nodeVisit.VisitInternalNode(((VarIntlNode)rt).value());traverse(((VarIntlNode)rt).leftchild());traverse(((VarIntlNode)rt).rightchild());}}Figure 5.10 An implementation for separate internal and leaf node representationsusing Java class inheritance and virtual functions.