aspects/core-aspects/src/main/java/org/apache/axiom/core/CoreParentNodeSupport.aj

/*
 * 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 org.apache.axiom.om.NodeUnavailableException;
import org.apache.axiom.om.OMContainer;
import org.apache.axiom.om.OMException;
import org.apache.axiom.om.OMNode;
import org.apache.axiom.om.OMXMLParserWrapper;
import org.apache.axiom.om.impl.builder.StAXBuilder;
import org.apache.axiom.om.impl.builder.StAXOMBuilder;

public aspect CoreParentNodeSupport {
    CoreChildNode CoreParentNode.firstChild;
    CoreChildNode CoreParentNode.lastChild;
    
    /**
     * Get the first child if it is available. The child is available if it is complete or
     * if the builder has started building the node. In the latter case,
     * {@link OMNode#isComplete()} may return <code>false</code> when called on the child. 
     * In contrast to {@link OMContainer#getFirstOMChild()}, this method will never modify
     * the state of the underlying parser.
     * 
     * @return the first child or <code>null</code> if the container has no children or
     *         the builder has not yet started to build the first child
     */
    public CoreChildNode CoreParentNode.coreGetFirstChildIfAvailable() {
        return firstChild;
    }

    public CoreChildNode CoreParentNode.coreGetLastKnownChild() {
        return lastChild;
    }

    public void CoreParentNode.buildNext() {
        OMXMLParserWrapper builder = getBuilder();
        if (builder == null) {
            throw new IllegalStateException("The node has no builder");
        } else if (((StAXOMBuilder)builder).isClosed()) {
            throw new OMException("The builder has already been closed");
        } else if (!builder.isCompleted()) {
            builder.next();
        } else {
            // If the builder is suddenly complete, but the completion status of the node
            // doesn't change, then this means that we built the wrong nodes
            throw new IllegalStateException("Builder is already complete");
        }         
    }
    
    public CoreChildNode CoreParentNode.coreGetFirstChild() {
        CoreChildNode firstChild = coreGetFirstChildIfAvailable();
        if (firstChild == null) {
            switch (getState()) {
                case CoreParentNode.DISCARDED:
                    ((StAXBuilder)getBuilder()).debugDiscarded(this);
                    throw new NodeUnavailableException();
                case CoreParentNode.INCOMPLETE:
                    do {
                        buildNext();
                    } while (getState() == CoreParentNode.INCOMPLETE
                            && (firstChild = coreGetFirstChildIfAvailable()) == null);
            }
        }
        return firstChild;
    }

    public final CoreChildNode CoreParentNode.coreGetLastChild() {
        build();
        return lastChild;
    }

    public final void CoreParentNode.coreAppendChild(CoreChildNode child, boolean fromBuilder) {
        CoreParentNode parent = child.coreGetParent();
        if (!fromBuilder) {
            build();
        }
        if (parent == this && child == lastChild) {
            // The child is already the last node. 
            // We don't need to detach and re-add it.
            return;
        }
        child.coreDetach(null);
        child.internalSetParent(this);
        if (firstChild == null) {
            firstChild = child;
        } else {
            child.previousSibling = lastChild;
            lastChild.nextSibling = child;
        }
        lastChild = child;
    }

    public final void CoreParentNode.coreAppendChildren(CoreDocumentFragment fragment) {
        fragment.build();
        if (fragment.firstChild == null) {
            // Fragment is empty; nothing to do
            return;
        }
        build();
        CoreChildNode child = fragment.firstChild;
        while (child != null) {
            child.internalSetParent(this);
            child = child.nextSibling;
        }
        if (firstChild == null) {
            firstChild = fragment.firstChild;
        } else {
            fragment.firstChild.previousSibling = lastChild;
            lastChild.nextSibling = fragment.firstChild;
        }
        lastChild = fragment.lastChild;
        fragment.firstChild = null;
        fragment.lastChild = null;
    }

    public final void CoreParentNode.coreRemoveChildren(CoreDocument newOwnerDocument) {
        // We need to call this first because if may modify the state (applies to OMSourcedElements)
        CoreChildNode child = coreGetFirstChildIfAvailable();
        boolean updateState;
        if (getState() == INCOMPLETE && getBuilder() != null) {
            if (lastChild instanceof CoreParentNode) {
                ((CoreParentNode)lastChild).build();
            }
            ((StAXOMBuilder)getBuilder()).discard((OMContainer)this);
            updateState = true;
        } else {
            updateState = false;
        }
        while (child != null) {
            CoreChildNode nextSibling = child.nextSibling;
            child.previousSibling = null;
            child.nextSibling = null;
            child.internalUnsetParent(newOwnerDocument);
            child = nextSibling;
        }
        firstChild = null;
        lastChild = null;
        if (updateState) {
            coreSetState(COMPLETE);
        }
    }
}