StaxNavUtils.java

/*
 * JBoss, Home of Professional Open Source.
 * Copyright 2011, Red Hat, Inc., and individual contributors
 * as indicated by the @author tags. See the copyright.txt file in the
 * distribution for a full listing of individual contributors.
 *
 * This is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * This software is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this software; if not, write to the Free
 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
 */

package org.gatein.common.xml.stax.navigator;

import static org.gatein.common.xml.stax.navigator.Exceptions.contentRequired;
import static org.gatein.common.xml.stax.navigator.Exceptions.expectedElement;

import java.io.InputStream;
import java.io.Reader;
import java.util.Arrays;
import java.util.HashSet;
import java.util.Set;

import javax.xml.namespace.QName;
import javax.xml.stream.XMLInputFactory;

import org.gatein.common.xml.stax.navigator.builder.StaxNavBuilder;
import org.gatein.common.xml.stax.navigator.builder.StaxNavBuilderImpl;
import org.staxnav.EnumElement;
import org.staxnav.Naming;
import org.staxnav.StaxNavException;
import org.staxnav.StaxNavigator;
import org.staxnav.ValueType;

/**
 * @author <a href="mailto:nscavell@redhat.com">Nick Scavelli</a>
 * @version $Revision$
 */
public class StaxNavUtils {
    public static <N> StaxNavigator<N> createNavigator(Naming<N> naming, InputStream in) throws StaxNavException {
        return buildDefaultNavigator().withInputStream(in).build(naming);
    }

    public static StaxNavigator<String> createNavigator(InputStream in) throws StaxNavException {
        return createNavigator(new Naming.Local(), in);
    }

    public static StaxNavigator<QName> createQualifiedNavigator(InputStream in) throws StaxNavException {
        return createNavigator(new Naming.Qualified(), in);
    }

    public static <E extends Enum<E> & EnumElement<E>> StaxNavigator<E> createNavigator(Class<E> enumeratedClass,
            E noSuchElement, InputStream in) throws StaxNavException {
        Naming<E> naming;
        if (EnumElement.class.isAssignableFrom(enumeratedClass)) {
            naming = new Naming.Enumerated.Mapped<E>(enumeratedClass, noSuchElement);
        } else {
            naming = new Naming.Enumerated.Simple<E>(enumeratedClass, noSuchElement);
        }

        return createNavigator(naming, in);
    }

    public static <N> StaxNavigator<N> createNavigator(Naming<N> naming, Reader reader) throws StaxNavException {
        return buildDefaultNavigator().withReader(reader).build(naming);
    }

    public static StaxNavigator<String> createNavigator(Reader reader) throws StaxNavException {
        return createNavigator(new Naming.Local(), reader);
    }

    public static StaxNavigator<QName> createQualifiedNavigator(Reader reader) throws StaxNavException {
        return createNavigator(new Naming.Qualified(), reader);
    }

    public static <E extends Enum<E> & EnumElement<E>> StaxNavigator<E> createNavigator(Class<E> enumeratedClass,
            E noSuchElement, Reader reader) throws StaxNavException {
        Naming<E> naming;
        if (EnumElement.class.isAssignableFrom(enumeratedClass)) {
            naming = new Naming.Enumerated.Mapped<E>(enumeratedClass, noSuchElement);
        } else {
            naming = new Naming.Enumerated.Simple<E>(enumeratedClass, noSuchElement);
        }

        return createNavigator(naming, reader);
    }

    public static <N> void requiresChild(StaxNavigator<N> navigator, N element) {
        if (navigator.child() != element) {
            throw expectedElement(navigator, element);
        }
    }

    public static <N> void requiresSibling(StaxNavigator<N> navigator, N element) {
        if (!navigator.sibling(element)) {
            throw expectedElement(navigator, element);
        }
    }

    public static String getRequiredAttribute(StaxNavigator navigator, String attributeName) throws StaxNavException {
        String value = navigator.getAttribute(attributeName);
        if (value == null) {
            throw new StaxNavException(navigator.getLocation(), "Attribute '" + attributeName + "' is required for element '"
                    + navigator.getLocalName() + "'");
        }

        return value;
    }

    public static <N> String getContent(StaxNavigator<N> navigator, boolean trim) {
        boolean before = navigator.getTrimContent();
        try {
            navigator.setTrimContent(trim);
            return navigator.getContent();
        } finally {
            navigator.setTrimContent(before);
        }
    }

    public static <N> String getRequiredContent(StaxNavigator<N> navigator, boolean trim) {
        String content = getContent(navigator, trim);
        if (content == null || content.length() == 0) {
            throw contentRequired(navigator);
        }

        return content;
    }

    public static <N, V> V parseContent(StaxNavigator<N> navigator, ValueType<V> valueType, V defaultValue) {
        String content = getContent(navigator, true);
        if (content != null && content.length() != 0) {
            return navigator.parseContent(valueType);
        } else {
            return defaultValue;
        }
    }

    public static <N, V> V parseRequiredContent(StaxNavigator<N> navigator, ValueType<V> valueType) {
        V value = parseContent(navigator, valueType, null);
        if (value == null) {
            throw contentRequired(navigator);
        }

        return value;
    }

    public static <N> Set<N> forNames(N... names) {
        return new HashSet<N>(Arrays.asList(names));
    }

    public static <N> StaxNavigator<N> child(StaxNavigator<N> navigator, N name) {
        if (!name.equals(navigator.child())) {
            throw expectedElement(navigator, name);
        }

        return navigator;
    }

    public static <N> StaxNavigator<N> sibling(StaxNavigator<N> navigator, N name) {
        if (!name.equals(navigator.sibling())) {
            throw expectedElement(navigator, name);
        }

        return navigator;
    }

    private static StaxNavBuilder buildDefaultNavigator() {
        return new StaxNavBuilderImpl()
                // Do not support external entities in XML documents.
                .withProperty(XMLInputFactory.IS_SUPPORTING_EXTERNAL_ENTITIES, false);
    }

    private StaxNavUtils() {
    }
}