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1   /**
2    * This file Copyright (c) 2015-2016 Magnolia International
3    * Ltd.  (http://www.magnolia-cms.com). All rights reserved.
4    *
5    *
6    * This file is dual-licensed under both the Magnolia
7    * Network Agreement and the GNU General Public License.
8    * You may elect to use one or the other of these licenses.
9    *
10   * This file is distributed in the hope that it will be
11   * useful, but AS-IS and WITHOUT ANY WARRANTY; without even the
12   * implied warranty of MERCHANTABILITY or FITNESS FOR A
13   * PARTICULAR PURPOSE, TITLE, or NONINFRINGEMENT.
14   * Redistribution, except as permitted by whichever of the GPL
15   * or MNA you select, is prohibited.
16   *
17   * 1. For the GPL license (GPL), you can redistribute and/or
18   * modify this file under the terms of the GNU General
19   * Public License, Version 3, as published by the Free Software
20   * Foundation.  You should have received a copy of the GNU
21   * General Public License, Version 3 along with this program;
22   * if not, write to the Free Software Foundation, Inc., 51
23   * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
24   *
25   * 2. For the Magnolia Network Agreement (MNA), this file
26   * and the accompanying materials are made available under the
27   * terms of the MNA which accompanies this distribution, and
28   * is available at http://www.magnolia-cms.com/mna.html
29   *
30   * Any modifications to this file must keep this entire header
31   * intact.
32   *
33   */
34  package info.magnolia.resourceloader;
35  
36  /**
37   * Common interface for all resource file origins (e.g. file-system, classpath, JCR).
38   *
39   * @param <P> the type of {@link Resource} this implementation of ResourceOrigin produces.
40   */
41  public interface ResourceOrigin<P extends Resource> {
42  
43      /**
44       * Returns the name of this origin. This may be used to describe/differentiate origin instances, and generate i18n keys accordingly.
45       */
46      String getName();
47  
48      /**
49       * Returns the {@link Resource} for this origin's declared root.
50       */
51      P getRoot();
52  
53      /**
54       * Traverses this ResourceOrigin from the root, according to the given {@link ResourceVisitor}.
55       *
56       * @see ResourceVisitor
57       * @see info.magnolia.resourceloader.util.PredicatedResourceVisitor
58       * @see info.magnolia.resourceloader.util.ResourceTreeWalker
59       */
60      void traverseWith(ResourceVisitor visitor);
61  
62      /**
63       * Sets up observation for this origin, and hooks it to the given callback {@link ResourceVisitor}.
64       *
65       * @see ResourceVisitor
66       * @see info.magnolia.resourceloader.util.PredicatedResourceVisitor
67       */
68      void watchForChanges(ResourceVisitor visitor);
69  
70      /**
71       * Retrieves a {@link Resource} object based on the given path. The given path may or may not start with a
72       * leading /, but will always be considered relative to whatever root path this origin uses; for the user of this
73       * class, such paths should thus be considered absolute, depending on the implementation, they may be relative
74       * to some other path. Directory traversal navigation should be prohibited by implementations for security reasons.
75       *
76       * @throws ResourceNotFoundException if the path does not exist in this ResourceOrigin
77       */
78      P getByPath(String path);
79      // P getByPath(Resource relativeTo, String relPath);
80  
81      boolean hasPath(String path);
82  
83      /**
84       * Thrown when a given path can't be found.
85       */
86      class ResourceNotFoundException extends RuntimeException {
87          public ResourceNotFoundException(ResourceOrigin origin, String path) {
88              super("No resource found for path " + path + " in origin " + origin.getName());
89          }
90      }
91  
92  }