// © Copyright 1999, Joseph Bergin.  All rights reserved. 

package gates;

import cs1.Die;

class Gate	// Constant output gate
{	public Gate() {} // true gate
	public Gate(boolean b){output = b;}
	
	public boolean output(){return output;}
	
	public void connect(Gate g){} // nothing
	
	private boolean output = true;
	protected void output(boolean b)	{output = b;}
}

class Switch extends Gate
{	public Switch(){} // initially true = ON
	public Switch(boolean b){super(b);}
	public void flip(){output(!output());}
}

class UnaryGate extends Gate //pass thru and root of unary gate hierarchy
{	public UnaryGate(){}
	public UnaryGate(Gate input){this.input = input;}

	public void connect(Gate input){this.input = input;}
	
	public boolean output()
	{	if(input != null)return input.output();
		return (new Die(2)).roll() == 0; // random output if not connected. 
	} 

	private Gate input = null;
}

class NotGate extends UnaryGate // Flips its input
{	public NotGate(){}
	public NotGate(Gate input){super(input);}
	
	public boolean output()
	{	return ! super.output();
	}
}

abstract class BinaryGate extends Gate // root of binary gate hierarchy
{	public BinaryGate(){}
	public BinaryGate(Gate left, Gate right){leftInput = left; rightInput = right;}
	public void connect(Gate g)
	{	if(leftInput == null)
			leftInput = g;
		else
			rightInput = g;
	}
	
	private Gate leftInput = null, rightInput = null;

	protected boolean left()
	{	if(leftInput != null)return leftInput.output();
		return false;
	}
	
	protected boolean right()
	{	if(rightInput != null)return rightInput.output();
		return false;
	}
}

class AndGate extends BinaryGate
{	public AndGate(){}
	public AndGate(Gate left, Gate right){super(left,right);}
	
	public boolean output()
	{	return left() && right();
	}
}

class OrGate extends BinaryGate
{	public OrGate(){}
	public OrGate(Gate left, Gate right){super(left,right);}
	
	public boolean output()
	{	return left() || right();
	}
}

public class GateTest 
{
	public static void main(String args[]) 
	{	Switch TG = new Switch(true);
		Switch FG = new Switch(false);
		AndGate And1 = new AndGate(TG, FG);
		OrGate Or1 = new OrGate(And1, FG);
		NotGate Not1 = new NotGate(Or1);
		
		System.out.println(Not1.output());
		FG.flip();
		System.out.println(Not1.output());
		TG.flip();
		System.out.println(Not1.output());
		FG.flip();
		System.out.println(Not1.output());
		
		TG.flip();
		FG.flip();
		Adder add = new Adder(TG, FG);
		System.out.println("Adder " + add.output()[0] + " " + add.output()[1]);
		try 
		{	System.in.read(); // prevent console window from going away
		} catch (java.io.IOException e) {}
	}
}