all.java

public class Add extends Operation{

    Add(Node left, Node right) {
        super(left, right);
    }

    @Override
    public int execute() {
        return op(0).execute() + op(1).execute();
    }

    @Override
    public String opString() {
        return "+";
    }
}
public abstract class Operation implements Node{

    private Node[] ops;

    public Node op(int i) {
        return ops[i];
    }

    public int nbOps() {
        return ops.length;
    }

    public Operation(Node... ops) {
        this.ops = ops;
    }

    public abstract String opString();

    public String toString(){
        String ret = "( "+this.opString() +" ";
        for (int i=0; i<nbOps(); i++) {
            ret+=op(i).toString()+" ";
        }
        ret += ")";
        return ret;
    }

}
public class Variable extends Scalar {
    String name;

    Variable(String name) {
        super(0);
        this.name = name;
    }

    public void set(int v) {
        this.value = v;
    }

    @Override
    public String toString() {
        return name;
    }
}
public interface Node {

    int execute();
}
public class Neg extends Operation{

    Neg(Operation op) {
        super(op);
    }

    @Override
    public int execute() {
        return - op(0).execute();
    }

    @Override
    public String opString() {
        return "-";
    }
}
public class Main {
    public static void main(String[] args) {
        Add op1 = new Add(new Scalar(1),new Scalar(2));
        Add op2 = new Add(new Scalar(3), new Scalar(4));
        Add op3 = new Add(op1, new Neg(op2));
        System.out.println(op3.execute());
        Variable x = new Variable("x");
        Set set = new Set(x,new Scalar(22));
        System.out.println(set);
        System.out.println(set.execute());
        Add op4 = new Add(x, new Scalar(20));
        System.out.println(op4);
        System.out.println(op4.execute());
    }
}public class Scalar implements Node{

    protected int value;
    Scalar(int value) {
        this.value = value;
    }
    public int get(){
        return value;
    }

    @Override
    public String toString(){
        return Integer.toString(value);
    }

    @Override
    public int execute() {
        return value;
    }
}
public class Set extends Operation{

    Variable variable;
    Node node;

    Set(Variable variable, Node node) {
        super(variable, node);
        this.variable = variable;
        this.node = node;
    }

    @Override
    public int execute() {
        this.variable.set(this.node.execute());
        return 1;
    }

    @Override
    public String opString() {
        return "set!";
    }
}
public class Add extends Operation{

    Add(Node left, Node right) {
        super(left, right);
    }

    @Override
    public int execute() {
        return op(0).execute() + op(1).execute();
    }

    @Override
    public String opString() {
        return "+";
    }
}
public abstract class Operation implements Node{

    private Node[] ops;

    public Node op(int i) {
        return ops[i];
    }

    public int nbOps() {
        return ops.length;
    }

    public Operation(Node... ops) {
        this.ops = ops;
    }

    public abstract String opString();

    public String toString(){
        String ret = "( "+this.opString() +" ";
        for (int i=0; i<nbOps(); i++) {
            ret+=op(i).toString()+" ";
        }
        ret += ")";
        return ret;
    }

}
public class Variable extends Scalar {
    String name;

    Variable(String name) {
        super(0);
        this.name = name;
    }

    public void set(int v) {
        this.value = v;
    }

    @Override
    public String toString() {
        return name;
    }
}
public interface Node {

    int execute();
}
public class Neg extends Operation{

    Neg(Operation op) {
        super(op);
    }

    @Override
    public int execute() {
        return - op(0).execute();
    }

    @Override
    public String opString() {
        return "-";
    }
}
public class Main {
    public static void main(String[] args) {
        Add op1 = new Add(new Scalar(1),new Scalar(2));
        Add op2 = new Add(new Scalar(3), new Scalar(4));
        Add op3 = new Add(op1, new Neg(op2));
        System.out.println(op3.execute());
        Variable x = new Variable("x");
        Set set = new Set(x,new Scalar(22));
        System.out.println(set);
        System.out.println(set.execute());
        Add op4 = new Add(x, new Scalar(20));
        System.out.println(op4);
        System.out.println(op4.execute());
    }
}public class Scalar implements Node{

    protected int value;
    Scalar(int value) {
        this.value = value;
    }
    public int get(){
        return value;
    }

    @Override
    public String toString(){
        return Integer.toString(value);
    }

    @Override
    public int execute() {
        return value;
    }
}
public class Set extends Operation{

    Variable variable;
    Node node;

    Set(Variable variable, Node node) {
        super(variable, node);
        this.variable = variable;
        this.node = node;
    }

    @Override
    public int execute() {
        this.variable.set(this.node.execute());
        return 1;
    }

    @Override
    public String opString() {
        return "set!";
    }
}
public class Add extends Operation{

    Add(Node left, Node right) {
        super(left, right);
    }

    @Override
    public int execute() {
        return op(0).execute() + op(1).execute();
    }

    @Override
    public String opString() {
        return "+";
    }
}
public abstract class Operation implements Node{

    private Node[] ops;

    public Node op(int i) {
        return ops[i];
    }

    public int nbOps() {
        return ops.length;
    }

    public Operation(Node... ops) {
        this.ops = ops;
    }

    public abstract String opString();

    public String toString(){
        String ret = "( "+this.opString() +" ";
        for (int i=0; i<nbOps(); i++) {
            ret+=op(i).toString()+" ";
        }
        ret += ")";
        return ret;
    }

}
public class Variable extends Scalar {
    String name;

    Variable(String name) {
        super(0);
        this.name = name;
    }

    public void set(int v) {
        this.value = v;
    }

    @Override
    public String toString() {
        return name;
    }
}
public interface Node {

    int execute();
}
public class Neg extends Operation{

    Neg(Operation op) {
        super(op);
    }

    @Override
    public int execute() {
        return - op(0).execute();
    }

    @Override
    public String opString() {
        return "-";
    }
}
public class Main {
    public static void main(String[] args) {
        Add op1 = new Add(new Scalar(1),new Scalar(2));
        Add op2 = new Add(new Scalar(3), new Scalar(4));
        Add op3 = new Add(op1, new Neg(op2));
        System.out.println(op3.execute());
        Variable x = new Variable("x");
        Set set = new Set(x,new Scalar(22));
        System.out.println(set);
        System.out.println(set.execute());
        Add op4 = new Add(x, new Scalar(20));
        System.out.println(op4);
        System.out.println(op4.execute());
    }
}public class Scalar implements Node{

    protected int value;
    Scalar(int value) {
        this.value = value;
    }
    public int get(){
        return value;
    }

    @Override
    public String toString(){
        return Integer.toString(value);
    }

    @Override
    public int execute() {
        return value;
    }
}
public class Set extends Operation{

    Variable variable;
    Node node;

    Set(Variable variable, Node node) {
        super(variable, node);
        this.variable = variable;
        this.node = node;
    }

    @Override
    public int execute() {
        this.variable.set(this.node.execute());
        return 1;
    }

    @Override
    public String opString() {
        return "set!";
    }
}
public class Add extends Operation{

    Add(Node left, Node right) {
        super(left, right);
    }

    @Override
    public int execute() {
        return op(0).execute() + op(1).execute();
    }

    @Override
    public String opString() {
        return "+";
    }
}
public abstract class Operation implements Node{

    private Node[] ops;

    public Node op(int i) {
        return ops[i];
    }

    public int nbOps() {
        return ops.length;
    }

    public Operation(Node... ops) {
        this.ops = ops;
    }

    public abstract String opString();

    public String toString(){
        String ret = "( "+this.opString() +" ";
        for (int i=0; i<nbOps(); i++) {
            ret+=op(i).toString()+" ";
        }
        ret += ")";
        return ret;
    }

}
public class Variable extends Scalar {
    String name;

    Variable(String name) {
        super(0);
        this.name = name;
    }

    public void set(int v) {
        this.value = v;
    }

    @Override
    public String toString() {
        return name;
    }
}
public interface Node {

    int execute();
}
public class Neg extends Operation{

    Neg(Operation op) {
        super(op);
    }

    @Override
    public int execute() {
        return - op(0).execute();
    }

    @Override
    public String opString() {
        return "-";
    }
}
public class Main {
    public static void main(String[] args) {
        Add op1 = new Add(new Scalar(1),new Scalar(2));
        Add op2 = new Add(new Scalar(3), new Scalar(4));
        Add op3 = new Add(op1, new Neg(op2));
        System.out.println(op3.execute());
        Variable x = new Variable("x");
        Set set = new Set(x,new Scalar(22));
        System.out.println(set);
        System.out.println(set.execute());
        Add op4 = new Add(x, new Scalar(20));
        System.out.println(op4);
        System.out.println(op4.execute());
    }
}
public class Scalar implements Node{

    protected int value;
    Scalar(int value) {
        this.value = value;
    }
    public int get(){
        return value;
    }

    @Override
    public String toString(){
        return Integer.toString(value);
    }

    @Override
    public int execute() {
        return value;
    }
}
public class Set extends Operation{

    Variable variable;
    Node node;

    Set(Variable variable, Node node) {
        super(variable, node);
        this.variable = variable;
        this.node = node;
    }

    @Override
    public int execute() {
        this.variable.set(this.node.execute());
        return 1;
    }

    @Override
    public String opString() {
        return "set!";
    }
}