TldLocationsCache.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.sling.scripting.jsp.jasper.compiler;

import org.apache.sling.scripting.jsp.jasper.JasperException;


/**
 * A container for all tag libraries that are defined "globally"
 * for the web application.
 *
 * Tag Libraries can be defined globally in one of two ways:
 *   1. Via <taglib> elements in web.xml:
 *      the uri and location of the tag-library are specified in
 *      the <taglib> element.
 *   2. Via packaged jar files that contain .tld files
 *      within the META-INF directory, or some subdirectory
 *      of it. The taglib is 'global' if it has the <uri>
 *      element defined.
 *
 * A mapping between the taglib URI and its associated TaglibraryInfoImpl
 * is maintained in this container.
 * Actually, that's what we'd like to do. However, because of the
 * way the classes TagLibraryInfo and TagInfo have been defined,
 * it is not currently possible to share an instance of TagLibraryInfo
 * across page invocations. A bug has been submitted to the spec lead.
 * In the mean time, all we do is save the 'location' where the
 * TLD associated with a taglib URI can be found.
 *
 * When a JSP page has a taglib directive, the mappings in this container
 * are first searched (see method getLocation()).
 * If a mapping is found, then the location of the TLD is returned.
 * If no mapping is found, then the uri specified
 * in the taglib directive is to be interpreted as the location for
 * the TLD of this tag library.
 *
 * @author Pierre Delisle
 * @author Jan Luehe
 */

public abstract class TldLocationsCache {

    /**
     * The types of URI one may specify for a tag library
     */
    public static final int ABS_URI = 0;
    public static final int ROOT_REL_URI = 1;
    public static final int NOROOT_REL_URI = 2;

    public abstract String[] getLocation(String uri) throws JasperException;

    /**
     * Returns the type of a URI:
     *     ABS_URI
     *     ROOT_REL_URI
     *     NOROOT_REL_URI
     */
    public static int uriType(String uri) {
        if (uri.indexOf(':') != -1) {
            return ABS_URI;
        } else if (uri.startsWith("/")) {
            return ROOT_REL_URI;
        } else {
            return NOROOT_REL_URI;
        }
    }
}