/*******************************************************************************
 * Copyright (c) 2009 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
 *     Zend Technologies
 *******************************************************************************/
package org2.eclipse.php.internal.core.ast.nodes;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

import org2.eclipse.php.internal.core.PHPVersion;
import org2.eclipse.php.internal.core.ast.match.ASTMatcher;
import org2.eclipse.php.internal.core.ast.visitor.Visitor;

/**
 * This class represents an empty statement.
 * <pre>e.g.<pre> ;
 * while(true); - the while statement contains empty statement
 */
public class EmptyStatement extends Statement {

	/**
	 * A list of property descriptors (element type: 
	 * {@link StructuralPropertyDescriptor}),
	 * or null if uninitialized.
	 */
	private static final List<StructuralPropertyDescriptor> PROPERTY_DESCRIPTORS;
	
	static {
		List<StructuralPropertyDescriptor> properyList = new ArrayList<StructuralPropertyDescriptor>(0);
		PROPERTY_DESCRIPTORS = Collections.unmodifiableList(properyList);
	}
	
	public EmptyStatement(int start, int end, AST ast) {
		super(start, end, ast);
	}

	public EmptyStatement(AST ast) {
		super(ast);
	}
	
	public void accept0(Visitor visitor) {
		final boolean visit = visitor.visit(this);
		if (visit) {
			childrenAccept(visitor);
		}
		visitor.endVisit(this);
	}	
	
	public void childrenAccept(Visitor visitor) {
	}

	public void traverseTopDown(Visitor visitor) {
		accept(visitor);
	}

	public void traverseBottomUp(Visitor visitor) {
		accept(visitor);
	}

	public void toString(StringBuffer buffer, String tab) {
		buffer.append(tab).append("<EmptyStatement"); //$NON-NLS-1$
		appendInterval(buffer);
		buffer.append("/>"); //$NON-NLS-1$
	}

	public int getType() {
		return ASTNode.EMPTY_STATEMENT;
	}
	
	/* 
	 * Method declared on ASTNode.
	 */
	public boolean subtreeMatch(ASTMatcher matcher, Object other) {
		// dispatch to correct overloaded match method
		return matcher.match(this, other);
	}

	@Override
	ASTNode clone0(AST target) {
		final ASTNode result = new EmptyStatement(this.getStart(), this.getEnd(), target);
		return result;
	}

	@Override
	List<StructuralPropertyDescriptor> internalStructuralPropertiesForType(PHPVersion apiLevel) {
		return PROPERTY_DESCRIPTORS;
	}
}