package model;

public class Add implements Expression {
	private Expression left, right;
	
	public Add(Expression left, Expression right) {
		this.left = left;
		this.right = right;
	}

	@Override
	public Expression derivative() throws Exception {
		Expression deriv = new Add(this.left.derivative(), this.right.derivative());
		return null;
	}

	@Override
	public Expression integrate() {
		return null;
	}

	@Override
	public double calc() throws Exception {
		return this.left.calc() + this.right.calc();
	}

}

@@ -322,36 +322,37 @@
 ve());%0A%09%09return 
-null
+deriv
 ;%0A%09%7D%0A%0A%09@Override
@@ -387,23 +387,130 @@
 e() 
-%7B%0A%09%09return null
+throws Exception %7B%0A%09%09Expression integration = new Add(this.left.integrate(), this.right.integrate());%0A%09%09return integration
 ;%0A%09%7D

Add class functionality added