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/*
 * Fabric3
 * Copyright (c) 2009-2015 Metaform Systems
 *
 * 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.
 *
 * Portions originally based on Apache Tuscany 2007
 * licensed under the Apache 2.0 license.
 */
package org.fabric3.spi.introspection.xml;

import javax.xml.namespace.NamespaceContext;
import javax.xml.namespace.QName;
import javax.xml.stream.XMLStreamConstants;
import javax.xml.stream.XMLStreamException;
import javax.xml.stream.XMLStreamReader;

/**
 * Utility functions to support loader implementations.
 */
public final class LoaderUtil {
    private LoaderUtil() {
    }

    /**
     * Advance the stream to the next END_ELEMENT event skipping any nested content.
     *
     * @param reader the reader to advance
     * @throws XMLStreamException if there was a problem reading the stream
     */
    public static void skipToEndElement(XMLStreamReader reader) throws XMLStreamException {
        int depth = 0;
        while (true) {
            int event = reader.next();
            if (event == XMLStreamConstants.START_ELEMENT) {
                depth++;
            } else if (event == XMLStreamConstants.END_ELEMENT) {
                if (depth == 0) {
                    return;
                }
                depth--;
            }
        }
    }

    /**
     * Construct a QName from an XML value.
     *
     * @param text             the text of an XML QName; if null or "" then null will be returned
     * @param defaultNamespace the default namespace to use if none is defined
     * @param context          the context for resolving namespace prefixes
     * @return a QName with the appropriate namespace set
     */
    public static QName getQName(String text, String defaultNamespace, NamespaceContext context) {
        if (text == null || text.length() == 0) {
            return null;
        }

        int index = text.indexOf(':');
        if (index < 1 || index == text.length() - 1) {
            // unqualified form - use the default supplied
            return new QName(defaultNamespace, text);
        } else {
            String prefix = text.substring(0, index);
            String uri = context.getNamespaceURI(prefix);
            String localPart = text.substring(index + 1);
            return new QName(uri, localPart, prefix);
        }
    }

}