1 /*
2 * ModeShape (http://www.modeshape.org)
3 * See the COPYRIGHT.txt file distributed with this work for information
4 * regarding copyright ownership. Some portions may be licensed
5 * to Red Hat, Inc. under one or more contributor license agreements.
6 * See the AUTHORS.txt file in the distribution for a full listing of
7 * individual contributors.
8 *
9 * ModeShape is free software. Unless otherwise indicated, all code in ModeShape
10 * is licensed to you under the terms of the GNU Lesser General Public License as
11 * published by the Free Software Foundation; either version 2.1 of
12 * the License, or (at your option) any later version.
13 *
14 * ModeShape is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
17 * Lesser General Public License for more details.
18 *
19 * You should have received a copy of the GNU Lesser General Public
20 * License along with this software; if not, write to the Free
21 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
22 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
23 */
24 package org.modeshape.graph.connector.federation;
25
26 import java.util.List;
27 import net.jcip.annotations.Immutable;
28 import org.modeshape.graph.ExecutionContext;
29 import org.modeshape.graph.Location;
30 import org.modeshape.graph.property.Path;
31 import org.modeshape.graph.property.PathFactory;
32
33 /**
34 * A Projector for federated repository configurations that are an offset, direct one-for-one mirror against a single source
35 * repository with a subgraph projected below the federated root. In other words, the federated repository has a single projection
36 * with a single "/something/below/root => /source/node" rule. Note that this project works even when the path in source is the
37 * root node, such as "/something/below/root => /".
38 */
39 @Immutable
40 final class OffsetMirrorProjector extends ProjectorWithPlaceholders {
41
42 /**
43 * Attempt to create an instance of the {@link OffsetMirrorProjector} with the supplied projections using the supplied
44 * context.
45 *
46 * @param context the context; may not be null
47 * @param projections the projections in the federated repository; may not be null
48 * @return the offset mirror projector, or null if the projections didn't match the criteria for such a projector
49 */
50 static OffsetMirrorProjector with( ExecutionContext context,
51 List<Projection> projections ) {
52 assert projections != null;
53 assert context != null;
54 // There must be a single projection ...
55 if (projections.size() != 1) return null;
56 Projection projection = projections.get(0);
57 assert projection != null;
58 // That projection may only have one rule ...
59 if (projection.getRules().size() != 1) return null;
60 PathFactory pathFactory = context.getValueFactories().getPathFactory();
61
62 // The # of paths in repository must be 1 ...
63 List<Path> topLevelPaths = projection.getRules().get(0).getTopLevelPathsInRepository(pathFactory);
64 if (topLevelPaths.size() != 1) return null;
65 Path topLevelPath = topLevelPaths.get(0);
66 assert topLevelPath != null;
67 // The federated path may not be the root ...
68 if (topLevelPath.isRoot()) return null;
69
70 // The corresponding source path may or may not be the root ...
71 Path sourcePath = projection.getRules().get(0).getPathInSource(topLevelPath, pathFactory);
72
73 return new OffsetMirrorProjector(context, projections, topLevelPath, sourcePath);
74 }
75
76 private final Projection projection;
77 private final Path offset;
78 private final int offsetSize;
79 private final Path sourcePath;
80
81 private OffsetMirrorProjector( ExecutionContext context,
82 List<Projection> projections,
83 Path offset,
84 Path sourcePath ) {
85 super(context, projections);
86 this.projection = projections.get(0);
87 this.offset = offset;
88 this.offsetSize = offset.size();
89 this.sourcePath = sourcePath;
90 }
91
92 /**
93 * {@inheritDoc}
94 *
95 * @see org.modeshape.graph.connector.federation.Projector#project(ExecutionContext, Location, boolean)
96 */
97 public ProjectedNode project( ExecutionContext context,
98 Location location,
99 boolean requiresUpdate ) {
100 if (requiresUpdate && projection.isReadOnly()) return null;
101 PlaceholderNode placeholder = isPlaceholder(location);
102 if (placeholder != null) return placeholder;
103
104 Path path = location.getPath();
105 Location locationInSource = location;
106 if (path != null) {
107 if (path.size() == offsetSize) {
108 // Make sure the path is the same ...
109 if (path.equals(offset)) {
110 locationInSource = location.with(sourcePath);
111 } else {
112 return null; // not in the path
113 }
114 } else {
115 // Make sure the path begins with the offset ...
116 if (path.isDecendantOf(offset)) {
117 Path pathBelowOffset = path.relativeTo(offset);
118 PathFactory pathFactory = context.getValueFactories().getPathFactory();
119 Path pathInSource = pathFactory.create(sourcePath, pathBelowOffset);
120 locationInSource = location.with(pathInSource);
121 } else {
122 // Not in the path
123 return null;
124 }
125 }
126 }
127 return new ProxyNode(projection, locationInSource, location);
128 }
129
130 }