aspects/core-aspects/src/main/java/org/apache/axiom/core/AbstractNodeIterator.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied. See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package org.apache.axiom.core;

import java.util.ConcurrentModificationException;
import java.util.NoSuchElementException;

public abstract class AbstractNodeIterator<T> implements NodeIterator<T> {
    private final CoreParentNode startNode;
    private final Axis axis;
    private final Class<T> type;
    private final ExceptionTranslator exceptionTranslator;
    private final Semantics semantics;
    private CoreNode currentNode;
    
    /**
     * The parent of the current node. This is used to detect concurrent modifications.
     */
    private CoreParentNode currentParent;
    
    private CoreNode nextNode;
    private boolean hasNext;
    private int depth;
    
    public AbstractNodeIterator(CoreParentNode startNode, Axis axis, Class<T> type, ExceptionTranslator exceptionTranslator, Semantics semantics) {
        this.startNode = startNode;
        this.axis = axis;
        this.type = type;
        this.exceptionTranslator = exceptionTranslator;
        this.semantics = semantics;
    }

    protected abstract boolean matches(CoreNode node) throws CoreModelException;

    public final boolean hasNext() {
        if (!hasNext) {
            CoreNode node = currentNode;
            if (node instanceof CoreChildNode && ((CoreChildNode)node).coreGetParent() != currentParent) {
                throw new ConcurrentModificationException("The current node has been removed using a method other than Iterator#remove()");
            }
            try {
                do {
                    // Get to the next node
                    switch (axis) {
                        case CHILDREN:
                            if (node == null) {
                                node = startNode.coreGetFirstChild();
                            } else {
                                node = ((CoreChildNode)node).coreGetNextSibling();
                            }
                            break;
                        case DESCENDANTS:
                        case DESCENDANTS_OR_SELF:
                            if (node == null) {
                                if (axis == Axis.DESCENDANTS) {
                                    node = startNode.coreGetFirstChild();
                                    depth++;
                                } else {
                                    node = startNode;
                                }
                            } else {
                                boolean visitChildren = true;
                                while (true) {
                                    // TODO: test for CoreContainer instead????
                                    if (visitChildren && node instanceof CoreElement) {
                                        CoreChildNode firstChild = ((CoreElement)node).coreGetFirstChild();
                                        if (firstChild != null) {
                                            depth++;
                                            node = firstChild;
                                            break;
                                        }
                                    }
                                    if (depth == 0) {
                                        node = null;
                                        break;
                                    }
                                    CoreChildNode nextSibling = ((CoreChildNode)node).coreGetNextSibling();
                                    if (nextSibling != null) {
                                        node = nextSibling;
                                        break;
                                    }
                                    depth--;
                                    node = ((CoreChildNode)node).coreGetParent();
                                    visitChildren = false;
                                }
                            }
                    }
                } while (node != null && !matches(node));
            } catch (CoreModelException ex) {
                throw exceptionTranslator.toUncheckedException(ex);
            }
            nextNode = node;
            hasNext = true;
        }
        return nextNode != null;
    }

    public final T next() {
        if (hasNext()) {
            currentNode = nextNode;
            currentParent = currentNode instanceof CoreChildNode ? ((CoreChildNode)currentNode).coreGetParent() : null;
            hasNext = false;
            return type.cast(currentNode);
        } else {
            throw new NoSuchElementException();
        }
    }

    public final void remove() {
        if (currentNode == null) {
            throw new IllegalStateException();
        }
        // Move to next node before replacing the current one
        hasNext();
        if (currentNode instanceof CoreChildNode) {
//            try {
                ((CoreChildNode)currentNode).coreDetach(semantics);
//            } catch (CoreModelException ex) {
//                throw exceptionTranslator.toUncheckedException(ex);
//            }
        }
        currentNode = null;
    }

    public final void replace(CoreChildNode newNode) throws CoreModelException {
        // Move to next node before replacing the current one
        hasNext();
        ((CoreChildNode)currentNode).coreReplaceWith(newNode, semantics);
    }
}