content: /*******************************************************************************
   * Copyright (c) 2009 IBM Corporation and others.
   *
   * This program and the accompanying materials are made
   * available under the terms of the Eclipse Public License 2.0
   * which is available at https://www.eclipse.org/legal/epl-2.0/
   *
   * SPDX-License-Identifier: EPL-2.0
   * 
   * Contributors:
   *     IBM Corporation - initial API and implementation
   *     Zend Technologies
   *******************************************************************************/
  package org.eclipse.php.core.ast.nodes;
  
  /**
   * A node event handler is an internal mechanism for receiving notification of
   * changes to nodes in an AST.
   * <p>
   * The default implementation serves as the default event handler that does
   * nothing. Internal subclasses do all the real work.
   * </p>
   * 
   * @see AST#getEventHandler()
   */
  class NodeEventHandler {
  
  	/**
  	 * Creates a node event handler.
  	 */
  	NodeEventHandler() {
  		// default implementation: do nothing
  	}
  
  	/**
  	 * Reports that the given node is about to lose a child. The first half of an
  	 * event pair. The default implementation does nothing.
  	 * 
  	 * @param node
  	 *            the node about to be modified
  	 * @param child
  	 *            the node about to be removed
  	 * @param property
  	 *            the child or child list property descriptor
  	 * @see #postRemoveChildEvent(ASTNode, ASTNode, StructuralPropertyDescriptor)
  	 * @since 3.0
  	 */
  	void preRemoveChildEvent(ASTNode node, ASTNode child, StructuralPropertyDescriptor property) {
  		// do nothing
  		// System.out.println("DEL1 " + property);
  	}
  
  	/**
  	 * Reports that the given node has just lose a child. The second half of an
  	 * event pair. The default implementation does nothing.
  	 * 
  	 * @param node
  	 *            the node that was modified
  	 * @param child
  	 *            the child that was removed; note that this node is unparented
  	 * @param property
  	 *            the child or child list property descriptor
  	 * @see #preRemoveChildEvent(ASTNode, ASTNode, StructuralPropertyDescriptor)
  	 * @since 3.0
  	 */
  	void postRemoveChildEvent(ASTNode node, ASTNode child, StructuralPropertyDescriptor property) {
  		// do nothing
  		// System.out.println("DEL2 " + property);
  	}
  
  	/**
  	 * Reports that the given node is about to have a child replaced. The first half
  	 * of an event pair. The default implementation does nothing.
  	 * 
  	 * @param node
  	 *            the node about to be modified
  	 * @param child
  	 *            the node about to be replaced
  	 * @param newChild
  	 *            the replacement child; note that this node is unparented
  	 * @param property
  	 *            the child or child list property descriptor
  	 * @see #preReplaceChildEvent(ASTNode, ASTNode, ASTNode,
  	 *      StructuralPropertyDescriptor)
  	 * @since 3.0
  	 */
  	void preReplaceChildEvent(ASTNode node, ASTNode child, ASTNode newChild, StructuralPropertyDescriptor property) {
  		// do nothing
  		// System.out.println("REP1 " + property);
  	}
  
  	/**
  	 * Reports that the given node has had its child replaced. The second half of an
  	 * event pair. The default implementation does nothing.
  	 * 
  	 * @param node
  	 *            the node that was modified
  	 * @param child
  	 *            the node that was replaced; note that this node is unparented
  	 * @param newChild
  	 *            the replacement child
  	 * @param property
  	 *            the child or child list property descriptor
  	 * @see #postReplaceChildEvent(ASTNode, ASTNode, ASTNode,
  	 *      StructuralPropertyDescriptor)
  	 * @since 3.0
  	 */
  	void postReplaceChildEvent(ASTNode node, ASTNode child, ASTNode newChild, StructuralPropertyDescriptor property) {
  		// do nothing
  		// System.out.println("REP2 " + property);
  	}
  
  	/**
  	 * Reports that the given node is about to gain a child. The first half of an
  	 * event pair. The default implementation does nothing.
  	 * 
  	 * @param node
  	 *            the node that to be modified
  	 * @param child
  	 *            the node that is to be added as a child; note that this node is
  	 *            unparented; in the case of a child list property, the exact
  	 *            location of insertion is not supplied (but is known on the
  	 *            corresponding <code>postAddChildEvent</code> to follow)
  	 * @param property
  	 *            the child or child list property descriptor
  	 * @see #postAddChildEvent(ASTNode, ASTNode, StructuralPropertyDescriptor)
  	 * @since 3.0
  	 */
  	void preAddChildEvent(ASTNode node, ASTNode child, StructuralPropertyDescriptor property) {
  		// do nothing
  		// System.out.println("ADD1 " + property);
  	}
  
  	/**
  	 * Reports that the given node has just gained a child. The second half of an
  	 * event pair. The default implementation does nothing.
  	 * 
  	 * @param node
  	 *            the node that was modified
  	 * @param child
  	 *            the node that was added as a child
  	 * @param property
  	 *            the child or child list property descriptor
  	 * @see #preAddChildEvent(ASTNode, ASTNode, StructuralPropertyDescriptor)
  	 * @since 3.0
  	 */
  	void postAddChildEvent(ASTNode node, ASTNode child, StructuralPropertyDescriptor property) {
  		// do nothing
  		// System.out.println("ADD2 " + property);
  	}
  
  	/**
  	 * Reports that the given node is about to change the value of a non-child
  	 * property. The first half of an event pair. The default implementation does
  	 * nothing.
  	 * 
  	 * @param node
  	 *            the node to be modified
  	 * @param property
  	 *            the property descriptor
  	 * @see #postValueChangeEvent(ASTNode, SimplePropertyDescriptor)
  	 * @since 3.0
  	 */
  	void preValueChangeEvent(ASTNode node, SimplePropertyDescriptor property) {
  		// do nothing
  		// System.out.println("MOD1 " + property);
  	}
  
  	/**
  	 * Reports that the given node has just changed the value of a non-child
  	 * property. The second half of an event pair. The default implementation does
  	 * nothing.
  	 * 
  	 * @param node
  	 *            the node that was modified
  	 * @param property
  	 *            the property descriptor
  	 * @see #preValueChangeEvent(ASTNode, SimplePropertyDescriptor)
  	 * @since 3.0
  	 */
  	void postValueChangeEvent(ASTNode node, SimplePropertyDescriptor property) {
  		// do nothing
  		// System.out.println("MOD2 " + property);
  	}
  
  	/**
  	 * Reports that the given node is about to be cloned. The first half of an event
  	 * pair. The default implementation does nothing.
  	 * 
  	 * @param node
  	 *            the node to be modified
  	 * @see #postCloneNodeEvent(ASTNode, ASTNode)
  	 * @since 3.0
  	 */
  	void preCloneNodeEvent(ASTNode node) {
  		// do nothing
  		// System.out.println("CLONE1");
  	}
  
  	/**
  	 * Reports that the given node has just been cloned. The second half of an event
  	 * pair. The default implementation does nothing.
  	 * 
  	 * @param node
  	 *            the node that was modified
  	 * @param clone
  	 *            the clone of <code>node</code>
  	 * @see #preCloneNodeEvent(ASTNode)
  	 * @since 3.0
  	 */
  	void postCloneNodeEvent(ASTNode node, ASTNode clone) {
  		// do nothing
  		// System.out.println("CLONE2");
  	}
  
  }
  