package gve.calc.logic;

import java.awt.*;
import gve.calc.formula.*;

 A formula with one (right==null) or two (right!=null) children 
public class TableauPart extends Part {
	
 right can be null; top and left always are !=null 
	public Part top,left,right;

	private TableauPart(Part t) {
		top = t; t.setParent(this);
	}

	public TableauPart(Part t,Part ch) {
		this(t);
		left = ch; ch.setParent(this);
	}

	public TableauPart(Part t,Part l,Part r) {
		this(t,l);
		right = r; r.setParent(this);
	}

	public Part getChild(int count) {
		switch (count) {
		case 0: return top;
		case 1: return left;
		case 2: return right;
		default: return null;
		}
	}

	
 Returns true if this part has already been reduced. Visibly;
	  this condition is the same as "has p a line originating downwards?". 
	public static boolean hasReduction(Part p) {
		if (p.getParent() instanceof TableauPart) {
			TableauPart tp = (TableauPart)p.getParent();
			if (tp.top == p) return true;
		}
		return false;
	}

	public Object clone() {
		return new TableauPart(top,left,right);
	}

	public Part evaluate(Evaluator ev) { return null; }

	public void replaceChild(Part ch,Part byThat) {
		if (ch == left) {
			left = byThat; byThat.setParent(this);
		} else if (ch == top) {
			top = byThat; byThat.setParent(this);
		} else if (ch == right) {
			right = byThat; byThat.setParent(this);
		}
	}

	public String toString() {
		String r;
		if (right == null) r = "";
		else r = ", right="+right;
		return "TableauPart[top="+top+", left="+left+r+"]";
	}

	public Component createView(FormulaView view) {
		return new TableauPartView(this,view);
	}

	public void write(java.io.Writer w) throws java.io.IOException {
		super.write(w);
		int count = (right == null) ? 1 : 2;
		w.write(count+"\n");
		top.write(w);
		left.write(w);
		if (right != null) right.write(w);
	}

	public static Part read(java.io.BufferedReader r) throws java.io.IOException,
			ClassNotFoundException,NoSuchMethodException,
			java.lang.reflect.InvocationTargetException,IllegalAccessException {
		int count = Integer.parseInt(r.readLine());
		Part top = Part.read(r);
		Part left = Part.read(r);
		if (count > 1) {
			Part right = Part.read(r);
			return new TableauPart(top,left,right);
		}
		return new TableauPart(top,left);
	}
}