/*******************************************************************************
 * Copyright (c) 2000, 2004 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;

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

/**
 * While statement AST node type.
 *
 * <pre>
 * WhileStatement:
 *    <b>while</b> <b>(</b> Expression <b>)</b> Statement
 * </pre>
 * 
 * @since 2.0
 */
public class WhileStatement extends Statement {

	/**
	 * The "expression" structural property of this node type.
	 * @since 3.0
	 */
	public static final ChildPropertyDescriptor EXPRESSION_PROPERTY = 
		new ChildPropertyDescriptor(WhileStatement.class, "expression", Expression.class, MANDATORY, CYCLE_RISK); //$NON-NLS-1$

	/**
	 * The "body" structural property of this node type.
	 * @since 3.0
	 */
	public static final ChildPropertyDescriptor BODY_PROPERTY = 
		new ChildPropertyDescriptor(WhileStatement.class, "body", Statement.class, MANDATORY, CYCLE_RISK); //$NON-NLS-1$

	/**
	 * A list of property descriptors (element type: 
	 * {@link StructuralPropertyDescriptor}),
	 * or null if uninitialized.
	 */
	private static final List PROPERTY_DESCRIPTORS;
	
	static {
		List propertyList = new ArrayList(3);
		createPropertyList(WhileStatement.class, propertyList);
		addProperty(EXPRESSION_PROPERTY, propertyList);
		addProperty(BODY_PROPERTY, propertyList);
		PROPERTY_DESCRIPTORS = reapPropertyList(propertyList);
	}

	/**
	 * Returns a list of structural property descriptors for this node type.
	 * Clients must not modify the result.
	 * 
	 * @param apiLevel the API level; one of the
	 * <code>AST.JLS&ast;</code> constants

	 * @return a list of property descriptors (element type: 
	 * {@link StructuralPropertyDescriptor})
	 * @since 3.0
	 */
	public static List propertyDescriptors(int apiLevel) {
		return PROPERTY_DESCRIPTORS;
	}
			
	/**
	 * The expression; lazily initialized; defaults to an unspecified, but 
	 * legal, expression.
	 */
	private Expression expression = null;

	/**
	 * The body statement; lazily initialized; defaults to an empty block 
	 * statement.
	 */
	private Statement body = null;

	/**
	 * Creates a new unparented while statement node owned by the given 
	 * AST. By default, the expresssion is unspecified, but legal, and
	 * the body statement is an empty block.
	 * <p>
	 * N.B. This constructor is package-private.
	 * </p>
	 * 
	 * @param ast the AST that is to own this node
	 */
	WhileStatement(AST ast) {
		super(ast);
	}

	/* (omit javadoc for this method)
	 * Method declared on ASTNode.
	 */
	final List internalStructuralPropertiesForType(int apiLevel) {
		return propertyDescriptors(apiLevel);
	}
	
	/* (omit javadoc for this method)
	 * Method declared on ASTNode.
	 */
	final ASTNode internalGetSetChildProperty(ChildPropertyDescriptor property, boolean get, ASTNode child) {
		if (property == EXPRESSION_PROPERTY) {
			if (get) {
				return getExpression();
			} else {
				setExpression((Expression) child);
				return null;
			}
		}
		if (property == BODY_PROPERTY) {
			if (get) {
				return getBody();
			} else {
				setBody((Statement) child);
				return null;
			}
		}
		// allow default implementation to flag the error
		return super.internalGetSetChildProperty(property, get, child);
	}
	
	/* (omit javadoc for this method)
	 * Method declared on ASTNode.
	 */
	final int getNodeType0() {
		return WHILE_STATEMENT;
	}

	/* (omit javadoc for this method)
	 * Method declared on ASTNode.
	 */
	ASTNode clone0(AST target) {
		WhileStatement result = new WhileStatement(target);
		result.setSourceRange(this.getStartPosition(), this.getLength());
		result.copyLeadingComment(this);
		result.setExpression((Expression) getExpression().clone(target));
		result.setBody((Statement) getBody().clone(target));
		return result;
	}

	/* (omit javadoc for this method)
	 * Method declared on ASTNode.
	 */
	final boolean subtreeMatch0(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) {
			// visit children in normal left to right reading order
			acceptChild(visitor, getExpression());
			acceptChild(visitor, getBody());
		}
		visitor.endVisit(this);
	}
	
	/**
	 * Returns the expression of this while statement.
	 * 
	 * @return the expression node
	 */ 
	public Expression getExpression() {
		if (this.expression == null) {
			// lazy init must be thread-safe for readers
			synchronized (this) {
				if (this.expression == null) {
					preLazyInit();
					this.expression = new SimpleName(this.ast);
					postLazyInit(this.expression, EXPRESSION_PROPERTY);
				}
			}
		}
		return this.expression;
	}
	
	/**
	 * Sets the expression of this while statement.
	 * 
	 * @param expression the expression node
	 * @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) {
		if (expression == null) {
			throw new IllegalArgumentException();
		}
		ASTNode oldChild = this.expression;
		preReplaceChild(oldChild, expression, EXPRESSION_PROPERTY);
		this.expression = expression;
		postReplaceChild(oldChild, expression, EXPRESSION_PROPERTY);
	}

	/**
	 * Returns the body of this while statement.
	 * 
	 * @return the body statement node
	 */ 
	public Statement getBody() {
		if (this.body == null) {
			// lazy init must be thread-safe for readers
			synchronized (this) {
				if (this.body == null) {
					preLazyInit();
					this.body = new Block(this.ast);
					postLazyInit(this.body, BODY_PROPERTY);
				}
			}
		}
		return this.body;
	}
	
	/**
	 * Sets the body of this while statement.
	 * <p>
	 * Special note: The Java language does not allow a local variable declaration
	 * to appear as the body of a while statement (they may only appear within a
	 * block). However, the AST will allow a <code>VariableDeclarationStatement</code>
	 * as the body of a <code>WhileStatement</code>. To get something that will
	 * compile, be sure to embed the <code>VariableDeclarationStatement</code>
	 * inside a <code>Block</code>.
	 * </p>
	 * 
	 * @param statement the body statement node
	 * @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 setBody(Statement statement) {
		if (statement == null) {
			throw new IllegalArgumentException();
		}
		ASTNode oldChild = this.body;
		preReplaceChild(oldChild, statement, BODY_PROPERTY);
		this.body = statement;
		postReplaceChild(oldChild, statement, BODY_PROPERTY);
	}
	
	/* (omit javadoc for this method)
	 * Method declared on ASTNode.
	 */
	int memSize() {
		return super.memSize() + 2 * 4;
	}
	
	/* (omit javadoc for this method)
	 * Method declared on ASTNode.
	 */
	int treeSize() {
		return
			memSize()
			+ (this.expression == null ? 0 : getExpression().treeSize())
			+ (this.body == null ? 0 : getBody().treeSize());
	}
}