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The coolest XML library for Java around. Define typesafe views (projections) to xml. Use XPath to read and write XML. Bind XML to Java collections. Requires at least Java6, supports Java8 features and has no further runtime dependencies.

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/**
 *  Copyright 2016 Sven Ewald
 *
 *  Licensed 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.xmlbeam;

import javax.xml.xpath.XPathExpressionException;

import org.xmlbeam.exceptions.XBException;
import org.xmlbeam.intern.DOMChangeListener;

/**
 *
 */
abstract class DomChangeTracker implements DOMChangeListener {

    private boolean needRefresh = true;

    @Override
    public void domChanged() {
        needRefresh = true;
    }

    void refreshForReadIfNeeded() {
        if (needRefresh) {
            invokeRefresh(false);
        }
    }

    abstract void refresh(boolean b) throws XPathExpressionException;

    void refreshForWriteIfNeeded() {
        if (needRefresh) {
            invokeRefresh(true);
        }
    }

    private void invokeRefresh(boolean b) {
        try {
            refresh(b);
            needRefresh = false;
        } catch (XPathExpressionException e) {
            needRefresh = true;
            throw new XBException("Unexpected error during evaluation.", e);
        }
    }
}