1 /**
2 * This file Copyright (c) 2017-2018 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.ui.framework.ioc;
35
36 import java.util.Objects;
37
38 import com.google.inject.Key;
39 import com.google.inject.Provider;
40
41 /**
42 * Special {@link com.google.inject.Scope scope} implementation which allows to proxy/cache
43 * instances coming from a specified scope in other scopes.
44 *
45 * Depending on the {@link CurrentUiContextReference} state proxy scope will behave
46 * differently.
47 * If the current scope is the specified original scope, proxy scope will
48 * merely delegate instance scoping to it.
49 *
50 * Otherwise, if the current scope is different from the original, the
51 * instance provider from the original scope will be passed to the
52 * {@link ProxyScope#proxyScope(Key, Provider, SessionStoreScope)} method.
53 *
54 * A known use case for such scope is the {@link UiBaseModule.EventBusProxyScope
55 * event bus protection mechanism}.
56 */
57 abstract class ProxyScope implements UiScope {
58
59 private final SessionStoreScope originalScope;
60 private final UiScopes allUiScopes;
61
62 /**
63 * @param originalScope the scope where the instances are coming from.
64 */
65 ProxyScope(SessionStoreScope originalScope, UiScopes allUiScopes) {
66 this.originalScope = originalScope;
67 this.allUiScopes = allUiScopes;
68 }
69
70 /**
71 * Proxy an instance coming from the original scope in the current one.
72 *
73 * @param <T> type of injected instance
74 * @param key injected instance key
75 * @param scopedProvider provider from the original scope
76 * @param currentScope actual current scope in which the injection happens
77 * @return provider which somehow wraps the {@code baseScopeProvider} and augments
78 * its result according to the current scope.
79 */
80 protected abstract <T> Provider<T> proxyScope(Key<T> key, Provider<T> scopedProvider, SessionStoreScope currentScope);
81
82 protected final SessionStoreScope getOriginalScope() {
83 return this.originalScope;
84 }
85
86 protected final UiScopes getAllUiScopes() {
87 return allUiScopes;
88 }
89
90 @Override
91 public <T> Provider<T> scope(Key<T> key, Provider<T> creator) {
92 final Provider<T> scopedProvider = originalScope.scope(key, creator);
93
94 return () -> {
95 boolean isEager = originalScope.isEager();
96 final UiContextReference currentUiContextReference = CurrentUiContextReference.get().getUiContextReference();
97 final UiContextAnnotation uiContextAnnotation = UiAnnotations.cast(currentUiContextReference.getAnnotation());
98
99 final SessionStoreScope currentScope = allUiScopes.getScope(uiContextAnnotation.getRelatedScopeAnnotation(isEager));
100
101 if (Objects.equals(originalScope, currentScope)) {
102 return scopedProvider.get();
103 }
104
105 return proxyScope(key, scopedProvider, currentScope).get();
106 };
107 }
108 }