/*******************************************************************************
 * Copyright © 2011, 2013 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 * IBM Corporation - initial API and implementation
 *
 *******************************************************************************/
package org.eclipse.edt.mof.egl.impl;

import org.eclipse.edt.mof.egl.*;
import org.eclipse.edt.mof.egl.utils.IRUtils;
import org.eclipse.edt.mof.egl.utils.TypeUtils;

public class TernaryExpressionImpl extends MultiOperandExpressionImpl implements TernaryExpression{

	private boolean initialized = false;

	private void ensureInitialized() {
		if (initialized) {
			return;
		}
		initialized = true;
		if (getOperands().isEmpty()) {
			getOperands().add(null);
			getOperands().add(null);
			getOperands().add(null);
		}
	}

	@Override
	protected Operation resolveOperation() {
		Operation op = IRUtils.getBinaryOperation(getOperandType(getFirst()), getOperandType(getSecond()), getOperator());
		if (op == null) throw new NoSuchFunctionError();
		return op;
	}


	@Override
	public Expression getFirst() {
		ensureInitialized();
		return getOperands().get(0);
	}


	@Override
	public Expression getSecond() {
		ensureInitialized();
		return getOperands().get(1);
	}


	@Override
	public Expression getThird() {
		ensureInitialized();
		return getOperands().get(2);
	}


	@Override
	public void setFirst(Expression expr) {
		ensureInitialized();
		getOperands().set(0, expr);		
	}


	@Override
	public void setSecond(Expression expr) {
		ensureInitialized();
		getOperands().set(1, expr);		
	}


	@Override
	public void setThird(Expression expr) {
		ensureInitialized();
		getOperands().set(2, expr);		
	}

	@Override
	public Type getType() {
		Expression secondExpr = getSecond();
		Expression thirdExpr = getThird();
		Type secondType = secondExpr == null ? null : secondExpr.getType();
		Type thirdType = thirdExpr == null ? null : thirdExpr.getType();
		if (secondType != null && thirdType != null) {
			return IRUtils.getCommonSupertype(secondType, thirdType);
		}
		else {
			return TypeUtils.Type_ANY;
		}
	}

	@Override
	public boolean isNullable() {
		Expression secondExpr = getSecond();
		if (secondExpr instanceof TypedElement && ((TypedElement)secondExpr).isNullable()) {
			return true;
		}

		Expression thirdExpr = getThird();
		if (thirdExpr instanceof TypedElement && ((TypedElement)thirdExpr).isNullable()) {
			return true;
		}

		return false;
	}
}