/*******************************************************************************
 * Copyright (c) 2000, 2003 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials 
 * are made available under the terms of the Common Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/cpl-v10.html
 * 
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/

package org.eclipse.jdt.core.dom;

/**
 * Return statement AST node type.
 *
 * <pre>
 * ReturnStatement:
 *    <b>return</b> [ Expression ] <b>;</b>
 * </pre>
 * 
 * @since 2.0
 */
public class ReturnStatement extends Statement {
			
	/**
	 * The expression; <code>null</code> for none; defaults to none.
	 */
	private Expression optionalExpression = null;
	
	/**
	 * Creates a new AST node for a return statement owned by the 
	 * given AST. By default, the statement has no expression.
	 * 
	 * @param ast the AST that is to own this node
	 */
	ReturnStatement(AST ast) {
		super(ast);
	}

	/* (omit javadoc for this method)
	 * Method declared on ASTNode.
	 */
	public int getNodeType() {
		return RETURN_STATEMENT;
	}

	/* (omit javadoc for this method)
	 * Method declared on ASTNode.
	 */
	ASTNode clone(AST target) {
		ReturnStatement result = new ReturnStatement(target);
		result.setSourceRange(this.getStartPosition(), this.getLength());
		result.copyLeadingComment(this);
		result.setExpression(
			(Expression) ASTNode.copySubtree(target, getExpression()));
		return result;
	}

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

	/* (omit javadoc for this method)
	 * Method declared on ASTNode.
	 */
	void accept0(ASTVisitor visitor) {
		boolean visitChildren = visitor.visit(this);
		if (visitChildren) {
			acceptChild(visitor, getExpression());
		}
		visitor.endVisit(this);
	}
	
	/**
	 * Returns the expression of this return statement, or 
	 * <code>null</code> if there is none.
	 * 
	 * @return the expression node, or <code>null</code> if there is none
	 */ 
	public Expression getExpression() {
		return optionalExpression;
	}
	
	/**
	 * Sets or clears the expression of this return statement.
	 * 
	 * @param expression the expression node, or <code>null</code> if 
	 *    there is none
	 * @exception IllegalArgumentException if:
	 * <ul>
	 * <li>the node belongs to a different AST</li>
	 * <li>the node already has a parent</li>
	 * <li>a cycle in would be created</li>
	 * </ul>
	 */ 
	public void setExpression(Expression expression) {
		// a ReturnStatement may occur inside an Expression - must check cycles
		replaceChild(this.optionalExpression, expression, true);
		this.optionalExpression = expression;
	}
	
	/* (omit javadoc for this method)
	 * Method declared on ASTNode.
	 */
	int memSize() {
		return super.memSize() + 1 * 4;
	}
	
	/* (omit javadoc for this method)
	 * Method declared on ASTNode.
	 */
	int treeSize() {
		return
			memSize()
			+ (optionalExpression == null ? 0 : getExpression().treeSize());
	}
}