| /******************************************************************************* |
| * Copyright (c) 2004 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 |
| *******************************************************************************/ |
| /* |
| * $RCSfile: ParseVisitor.java,v $ |
| * $Revision: 1.4 $ $Date: 2005/02/15 22:36:09 $ |
| */ |
| package org.eclipse.jem.internal.instantiation; |
| |
| /** |
| * A visitor for abstract parse expression trees. |
| * <p> |
| * For each different concrete Expression node type <it>T</it> there are |
| * a pair of methods: |
| * <ul> |
| * <li><code>public boolean visit(<it>T</it> node)</code> - Visits |
| * the given node to perform some arbitrary operation. If <code>true</code> |
| * is returned, the given node's child nodes will be visited next; however, |
| * if <code>false</code> is returned, the given node's child nodes will |
| * not be visited. The default implementation provided by this class does |
| * nothing and returns <code>true</code>. Subclasses may reimplement |
| * this method as needed.</li> |
| * <li><code>public void endVisit(<it>T</it> node)</code> - Visits |
| * the given node to perform some arbitrary operation. When used in the |
| * conventional way, this method is called after all of the given node's |
| * children have been visited (or immediately, if <code>visit</code> returned |
| * <code>false</code>). The default implementation provided by this class does |
| * nothing. Subclasses may reimplement this method as needed.</li> |
| * </ul> |
| * </p> |
| * In addition, there are a pair of methods for visiting AST nodes in the |
| * abstract, regardless of node type: |
| * <ul> |
| * <li><code>public void preVisit(ASTNode node)</code> - Visits |
| * the given node to perform some arbitrary operation. |
| * This method is invoked prior to the appropriate type-specific |
| * <code>visit</code> method. |
| * The default implementation of this method does nothing. |
| * Subclasses may reimplement this method as needed.</li> |
| * <li><code>public void postVisit(ASTNode node)</code> - Visits |
| * the given node to perform some arbitrary operation. |
| * This method is invoked after the appropriate type-specific |
| * <code>endVisit</code> method. |
| * The default implementation of this method does nothing. |
| * Subclasses may reimplement this method as needed.</li> |
| * </ul> |
| * <p> |
| * For nodes with list-valued properties, the child nodes within the list |
| * are visited in order. For nodes with multiple properties, the child nodes |
| * are visited in the order that most closely corresponds to the lexical |
| * reading order of the source program. For instance, for a type declaration |
| * node, the child ordering is: name, superclass, superinterfaces, and |
| * body declarations. |
| * </p> |
| * <p> |
| * While it is possible to modify the tree in the visitor, care is required to |
| * ensure that the consequences are as expected and desirable. |
| * During the course of an ordinary visit starting at a given node, every node |
| * in the subtree is visited exactly twice, first with <code>visit</code> and |
| * then with <code>endVisit</code>. During a traversal of a stationary tree, |
| * each node is either behind (after <code>endVisit</code>), ahead (before |
| * <code>visit</code>), or in progress (between <code>visit</code> and |
| * the matching <code>endVisit</code>). Changes to the "behind" region of the |
| * tree are of no consequence to the visit in progress. Changes to the "ahead" |
| * region will be taken in stride. Changes to the "in progress" portion are |
| * the more interesting cases. With a node, the various properties are arranged |
| * in a linear list, with a cursor that separates the properties that have |
| * been visited from the ones that are still to be visited (the cursor |
| * is between the elements, rather than on an element). The cursor moves from |
| * the head to the tail of this list, advancing to the next position just |
| * <it>before</it> <code>visit</code> if called for that child. After the child |
| * subtree has been completely visited, the visit moves on the child |
| * immediately after the cursor. Removing a child while it is being visited |
| * does not alter the course of the visit. But any children added at positions |
| * after the cursor are considered in the "ahead" portion and will be visited. |
| * </p> |
| * <p> |
| * Cases to watch out for: |
| * <ul> |
| * <li>Moving a child node further down the list. This could result in the |
| * child subtree being visited multiple times; these visits are sequential.</li> |
| * <li>Moving a child node up into an ancestor. If the new home for |
| * the node is in the "ahead" portion, the subtree will be visited |
| * a second time; again, these visits are sequential.</li> |
| * <li>Moving a node down into a child. If the new home for |
| * the node is in the "ahead" portion, the subtree will be visited |
| * a second time; in this case, the visits will be nested. In some cases, |
| * this can lead to a stack overflow or out of memory condition.</li> |
| * </ul> |
| * </p> |
| * |
| * Note: This is based upon the visit concept in org.eclipse.jdt.core.dom.ASTVisitor. |
| * |
| * @see Expression#accept |
| * |
| * @since 1.0.0 |
| */ |
| public class ParseVisitor { |
| /** |
| * Visits the given parse node prior to the type-specific visit. (before <code>visit</code>). |
| * <p> |
| * The default implementation does nothing. Subclasses may reimplement. |
| * </p> |
| * |
| * @param node |
| * the node to visit |
| */ |
| public void preVisit(PTExpression node) { |
| // default implementation: do nothing |
| } |
| |
| /** |
| * Visits the given parse node following the type-specific visit (after <code>endVisit</code>). |
| * <p> |
| * The default implementation does nothing. Subclasses may reimplement. |
| * </p> |
| * |
| * @param node |
| * the node to visit |
| */ |
| public void postVisit(PTExpression node) { |
| // default implementation: do nothing |
| } |
| |
| public boolean visit(PTArrayAccess node) { |
| return true; |
| } |
| public boolean visit(PTArrayCreation node) { |
| return true; |
| } |
| public boolean visit(PTArrayInitializer node) { |
| return true; |
| } |
| public boolean visit(PTBooleanLiteral node) { |
| return true; |
| } |
| public boolean visit(PTCastExpression node) { |
| return true; |
| } |
| public boolean visit(PTCharacterLiteral node) { |
| return true; |
| } |
| public boolean visit(PTClassInstanceCreation node) { |
| return true; |
| } |
| public boolean visit(PTConditionalExpression node) { |
| return true; |
| } |
| public boolean visit(PTFieldAccess node) { |
| return true; |
| } |
| public boolean visit(PTInfixExpression node) { |
| return true; |
| } |
| public boolean visit(PTInstanceof node) { |
| return true; |
| } |
| public boolean visit(PTInvalidExpression node) { |
| return true; |
| } |
| public boolean visit(PTMethodInvocation node) { |
| return true; |
| } |
| public boolean visit(PTName node) { |
| return true; |
| } |
| public boolean visit(PTNullLiteral node) { |
| return true; |
| } |
| public boolean visit(PTNumberLiteral node) { |
| return true; |
| } |
| public boolean visit(PTParenthesizedExpression node) { |
| return true; |
| } |
| public boolean visit(PTPrefixExpression node) { |
| return true; |
| } |
| public boolean visit(PTStringLiteral node) { |
| return true; |
| } |
| public boolean visit(PTThisLiteral node) { |
| return true; |
| } |
| public boolean visit(PTTypeLiteral node) { |
| return true; |
| } |
| public boolean visit(PTInstanceReference node) { |
| return true; |
| } |
| |
| public void endVisit(PTArrayAccess node) { |
| // default implementation: do nothing |
| } |
| public void endVisit(PTArrayCreation node) { |
| // default implementation: do nothing |
| } |
| public void endVisit(PTArrayInitializer node) { |
| // default implementation: do nothing |
| } |
| public void endVisit(PTBooleanLiteral node) { |
| // default implementation: do nothing |
| } |
| public void endVisit(PTCastExpression node) { |
| // default implementation: do nothing |
| } |
| public void endVisit(PTCharacterLiteral node) { |
| // default implementation: do nothing |
| } |
| public void endVisit(PTClassInstanceCreation node) { |
| // default implementation: do nothing |
| } |
| public void endVisit(PTConditionalExpression node) { |
| // default implementation: do nothing |
| } |
| public void endVisit(PTFieldAccess node) { |
| // default implementation: do nothing |
| } |
| public void endVisit(PTInfixExpression node) { |
| // default implementation: do nothing |
| } |
| public void endVisit(PTInstanceof node) { |
| // default implementation: do nothing |
| } |
| public void endVisit(PTInvalidExpression node) { |
| // default implementation: do nothing |
| } |
| public void endVisit(PTMethodInvocation node) { |
| // default implementation: do nothing |
| } |
| public void endVisit(PTName node) { |
| // default implementation: do nothing |
| } |
| public void endVisit(PTNullLiteral node) { |
| // default implementation: do nothing |
| } |
| public void endVisit(PTNumberLiteral node) { |
| // default implementation: do nothing |
| } |
| public void endVisit(PTParenthesizedExpression node) { |
| // default implementation: do nothing |
| } |
| public void endVisit(PTPrefixExpression node) { |
| // default implementation: do nothing |
| } |
| public void endVisit(PTStringLiteral node) { |
| // default implementation: do nothing |
| } |
| public void endVisit(PTThisLiteral node) { |
| // default implementation: do nothing |
| } |
| public void endVisit(PTTypeLiteral node) { |
| // default implementation: do nothing |
| } |
| public void endVisit(PTInstanceReference node) { |
| // default implementation: do nothing |
| } |
| |
| } |