/*******************************************************************************
 * 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 org.eclipse.php.internal.core.ast.nodes;

/**
 * Abstract base class for property descriptors of AST nodes.
 * There are three kinds of properties:
 * <ul>
 * <li>simple properties ({@link SimplePropertyDescriptor})
 * - properties where the value is a primitive (int, boolean)
 * or simple (String, InfixExprsssion.Operator) type other than an
 * AST node; for example, the identifier of a {@link SimpleName}</li>
 * <li>child properties ({@link ChildPropertyDescriptor})
 * - properties whose value is another AST node;
 * for example, the name of a {@link MethodDeclaration}</li>
 * <li>child list properties ({@link ChildListPropertyDescriptor})
 * - properties where the value is a list of AST nodes;
 * for example, the statements of a {@link Block}</li>
 * </ul>
 * 
 * @since 3.0
 */
public abstract class StructuralPropertyDescriptor {
	
	/**
	 * Property id.
	 */
	private final String propertyId;
	
	/**
	 * The concrete AST node type that owns this property.
	 */
	private final Class nodeClass;
	
	/**
	 * Creates a new property descriptor for the given node type
	 * with the given property id.
	 * Note that this constructor is declared package-private so that
	 * property descriptors can only be created by the AST
	 * implementation.
	 * 
	 * @param nodeClass concrete AST node type that owns this property
	 * @param propertyId the property id
	 */
	StructuralPropertyDescriptor(Class nodeClass, String propertyId) {
		if (nodeClass == null || propertyId == null) {
			throw new IllegalArgumentException();
		}
		this.propertyId = propertyId;
		this.nodeClass = nodeClass;
	}
	
	/**
	 * Returns the id of this property.
	 * 
	 * @return the property id
	 */
	public final String getId() {
		return this.propertyId;
	}
	
	/**
	 * Returns the AST node type that owns this property.
	 * <p>
	 * For example, for all properties of the node type
	 * TypeDeclaration, this method returns <code>TypeDeclaration.class</code>.
	 * </p>
	 * 
	 * @return the node type that owns this property
	 */
	public final Class getNodeClass() {
		return this.nodeClass;
	}
	
	/**
	 * Returns whether this property is a simple property
	 * (instance of {@link SimplePropertyDescriptor}.
	 * 
	 * @return <code>true</code> if this is a simple property, and 
	 * <code>false</code> otherwise
	 */
	public final boolean isSimpleProperty(){
		return (this instanceof SimplePropertyDescriptor);
	}
	
	/**
	 * Returns whether this property is a child property
	 * (instance of {@link ChildPropertyDescriptor}.
	 * 
	 * @return <code>true</code> if this is a child property, and 
	 * <code>false</code> otherwise
	 */
	public final boolean isChildProperty() {
		return (this instanceof ChildPropertyDescriptor);
	}
	
	/**
	 * Returns whether this property is a child list property
	 * (instance of {@link ChildListPropertyDescriptor}.
	 * 
	 * @return <code>true</code> if this is a child list property, and 
	 * <code>false</code> otherwise
	 */
	public final boolean isChildListProperty() { 
		return (this instanceof ChildListPropertyDescriptor);
	}

	/**
	 * Returns a string suitable for debug purposes.
	 * @return {@inheritDoc}
	 */
	public String toString() {
		StringBuffer b = new StringBuffer();
		if (isChildListProperty()) {
			b.append("ChildList"); //$NON-NLS-1$
		}
		if (isChildProperty()) {
			b.append("Child"); //$NON-NLS-1$
		}
		if (isSimpleProperty()) {
			b.append("Simple"); //$NON-NLS-1$
		}
		b.append("Property["); //$NON-NLS-1$
		if (this.nodeClass != null) {
			b.append(this.nodeClass.getName());
		}
		b.append(","); //$NON-NLS-1$
		if (this.propertyId != null) {
			b.append(this.propertyId);
		}
		b.append("]"); //$NON-NLS-1$
		return b.toString();
	}
}
