1 /*
2  * Copyright (C) 2008 Google Inc.
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  * http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 package com.google.inject;
18 
19 import static com.google.common.base.Preconditions.checkState;
20 
21 import com.google.inject.binder.AnnotatedBindingBuilder;
22 import com.google.inject.binder.AnnotatedConstantBindingBuilder;
23 import com.google.inject.binder.AnnotatedElementBuilder;
24 import com.google.inject.binder.LinkedBindingBuilder;
25 import com.google.inject.matcher.Matcher;
26 import com.google.inject.spi.Message;
27 import com.google.inject.spi.ProvisionListener;
28 import com.google.inject.spi.TypeConverter;
29 import com.google.inject.spi.TypeListener;
30 import java.lang.annotation.Annotation;
31 import java.lang.reflect.Method;
32 
33 /**
34  * A module whose configuration information is hidden from its environment by default. Only bindings
35  * that are explicitly exposed will be available to other modules and to the users of the injector.
36  * This module may expose the bindings it creates and the bindings of the modules it installs.
37  *
38  * <p>A private module can be nested within a regular module or within another private module using
39  * {@link Binder#install install()}. Its bindings live in a new environment that inherits bindings,
40  * type converters, scopes, and interceptors from the surrounding ("parent") environment. When you
41  * nest multiple private modules, the result is a tree of environments where the injector's
42  * environment is the root.
43  *
44  * <p>Guice EDSL bindings can be exposed with {@link #expose(Class) expose()}. {@literal @}{@link
45  * com.google.inject.Provides Provides} bindings can be exposed with the {@literal @}{@link Exposed}
46  * annotation:
47  *
48  * <pre>
49  * public class FooBarBazModule extends PrivateModule {
50  *   protected void configure() {
51  *     bind(Foo.class).to(RealFoo.class);
52  *     expose(Foo.class);
53  *
54  *     install(new TransactionalBarModule());
55  *     expose(Bar.class).annotatedWith(Transactional.class);
56  *
57  *     bind(SomeImplementationDetail.class);
58  *     install(new MoreImplementationDetailsModule());
59  *   }
60  *
61  *   {@literal @}Provides {@literal @}Exposed
62  *   public Baz provideBaz() {
63  *     return new SuperBaz();
64  *   }
65  * }
66  * </pre>
67  *
68  * <p>Private modules are implemented using {@link Injector#createChildInjector(Module[]) parent
69  * injectors}. When it can satisfy their dependencies, just-in-time bindings will be created in the
70  * root environment. Such bindings are shared among all environments in the tree.
71  *
72  * <p>The scope of a binding is constrained to its environment. A singleton bound in a private
73  * module will be unique to its environment. But a binding for the same type in a different private
74  * module will yield a different instance.
75  *
76  * <p>A shared binding that injects the {@code Injector} gets the root injector, which only has
77  * access to bindings in the root environment. An explicit binding that injects the {@code Injector}
78  * gets access to all bindings in the child environment.
79  *
80  * <p>To promote a just-in-time binding to an explicit binding, bind it:
81  *
82  * <pre>
83  *   bind(FooImpl.class);
84  * </pre>
85  *
86  * @author jessewilson@google.com (Jesse Wilson)
87  * @since 2.0
88  */
89 public abstract class PrivateModule implements Module {
90 
91   /** Like abstract module, the binder of the current private module */
92   private PrivateBinder binder;
93 
94   @Override
configure(Binder binder)95   public final synchronized void configure(Binder binder) {
96     checkState(this.binder == null, "Re-entry is not allowed.");
97 
98     // Guice treats PrivateModules specially and passes in a PrivateBinder automatically.
99     this.binder = (PrivateBinder) binder.skipSources(PrivateModule.class);
100     try {
101       configure();
102     } finally {
103       this.binder = null;
104     }
105   }
106 
107   /**
108    * Creates bindings and other configurations private to this module. Use {@link #expose(Class)
109    * expose()} to make the bindings in this module available externally.
110    */
configure()111   protected abstract void configure();
112 
113   /** Makes the binding for {@code key} available to other modules and the injector. */
expose(Key<T> key)114   protected final <T> void expose(Key<T> key) {
115     binder().expose(key);
116   }
117 
118   /**
119    * Makes a binding for {@code type} available to other modules and the injector. Use {@link
120    * AnnotatedElementBuilder#annotatedWith(Class) annotatedWith()} to expose {@code type} with a
121    * binding annotation.
122    */
expose(Class<?> type)123   protected final AnnotatedElementBuilder expose(Class<?> type) {
124     return binder().expose(type);
125   }
126 
127   /**
128    * Makes a binding for {@code type} available to other modules and the injector. Use {@link
129    * AnnotatedElementBuilder#annotatedWith(Class) annotatedWith()} to expose {@code type} with a
130    * binding annotation.
131    */
expose(TypeLiteral<?> type)132   protected final AnnotatedElementBuilder expose(TypeLiteral<?> type) {
133     return binder().expose(type);
134   }
135 
136   // everything below is copied from AbstractModule
137 
138   /** Returns the current binder. */
binder()139   protected final PrivateBinder binder() {
140     checkState(binder != null, "The binder can only be used inside configure()");
141     return binder;
142   }
143 
144   /** @see Binder#bindScope(Class, Scope) */
bindScope(Class<? extends Annotation> scopeAnnotation, Scope scope)145   protected final void bindScope(Class<? extends Annotation> scopeAnnotation, Scope scope) {
146     binder().bindScope(scopeAnnotation, scope);
147   }
148 
149   /** @see Binder#bind(Key) */
bind(Key<T> key)150   protected final <T> LinkedBindingBuilder<T> bind(Key<T> key) {
151     return binder().bind(key);
152   }
153 
154   /** @see Binder#bind(TypeLiteral) */
bind(TypeLiteral<T> typeLiteral)155   protected final <T> AnnotatedBindingBuilder<T> bind(TypeLiteral<T> typeLiteral) {
156     return binder().bind(typeLiteral);
157   }
158 
159   /** @see Binder#bind(Class) */
bind(Class<T> clazz)160   protected final <T> AnnotatedBindingBuilder<T> bind(Class<T> clazz) {
161     return binder().bind(clazz);
162   }
163 
164   /** @see Binder#bindConstant() */
bindConstant()165   protected final AnnotatedConstantBindingBuilder bindConstant() {
166     return binder().bindConstant();
167   }
168 
169   /** @see Binder#install(Module) */
install(Module module)170   protected final void install(Module module) {
171     binder().install(module);
172   }
173 
174   /** @see Binder#addError(String, Object[]) */
addError(String message, Object... arguments)175   protected final void addError(String message, Object... arguments) {
176     binder().addError(message, arguments);
177   }
178 
179   /** @see Binder#addError(Throwable) */
addError(Throwable t)180   protected final void addError(Throwable t) {
181     binder().addError(t);
182   }
183 
184   /** @see Binder#addError(Message) */
addError(Message message)185   protected final void addError(Message message) {
186     binder().addError(message);
187   }
188 
189   /** @see Binder#requestInjection(Object) */
requestInjection(Object instance)190   protected final void requestInjection(Object instance) {
191     binder().requestInjection(instance);
192   }
193 
194   /** @see Binder#requestStaticInjection(Class[]) */
requestStaticInjection(Class<?>.... types)195   protected final void requestStaticInjection(Class<?>... types) {
196     binder().requestStaticInjection(types);
197   }
198 
199   /*if[AOP]*/
200   /**
201    * @see Binder#bindInterceptor(com.google.inject.matcher.Matcher,
202    *     com.google.inject.matcher.Matcher, org.aopalliance.intercept.MethodInterceptor[])
203    */
bindInterceptor( Matcher<? super Class<?>> classMatcher, Matcher<? super Method> methodMatcher, org.aopalliance.intercept.MethodInterceptor... interceptors)204   protected final void bindInterceptor(
205       Matcher<? super Class<?>> classMatcher,
206       Matcher<? super Method> methodMatcher,
207       org.aopalliance.intercept.MethodInterceptor... interceptors) {
208     binder().bindInterceptor(classMatcher, methodMatcher, interceptors);
209   }
210   /*end[AOP]*/
211 
212   /** Instructs Guice to require a binding to the given key. */
requireBinding(Key<?> key)213   protected final void requireBinding(Key<?> key) {
214     binder().getProvider(key);
215   }
216 
217   /** Instructs Guice to require a binding to the given type. */
requireBinding(Class<?> type)218   protected final void requireBinding(Class<?> type) {
219     binder().getProvider(type);
220   }
221 
222   /** @see Binder#getProvider(Key) */
getProvider(Key<T> key)223   protected final <T> Provider<T> getProvider(Key<T> key) {
224     return binder().getProvider(key);
225   }
226 
227   /** @see Binder#getProvider(Class) */
getProvider(Class<T> type)228   protected final <T> Provider<T> getProvider(Class<T> type) {
229     return binder().getProvider(type);
230   }
231 
232   /**
233    * @see Binder#convertToTypes(com.google.inject.matcher.Matcher,
234    *     com.google.inject.spi.TypeConverter)
235    */
convertToTypes( Matcher<? super TypeLiteral<?>> typeMatcher, TypeConverter converter)236   protected final void convertToTypes(
237       Matcher<? super TypeLiteral<?>> typeMatcher, TypeConverter converter) {
238     binder().convertToTypes(typeMatcher, converter);
239   }
240 
241   /** @see Binder#currentStage() */
currentStage()242   protected final Stage currentStage() {
243     return binder().currentStage();
244   }
245 
246   /** @see Binder#getMembersInjector(Class) */
getMembersInjector(Class<T> type)247   protected <T> MembersInjector<T> getMembersInjector(Class<T> type) {
248     return binder().getMembersInjector(type);
249   }
250 
251   /** @see Binder#getMembersInjector(TypeLiteral) */
getMembersInjector(TypeLiteral<T> type)252   protected <T> MembersInjector<T> getMembersInjector(TypeLiteral<T> type) {
253     return binder().getMembersInjector(type);
254   }
255 
256   /**
257    * @see Binder#bindListener(com.google.inject.matcher.Matcher, com.google.inject.spi.TypeListener)
258    */
bindListener(Matcher<? super TypeLiteral<?>> typeMatcher, TypeListener listener)259   protected void bindListener(Matcher<? super TypeLiteral<?>> typeMatcher, TypeListener listener) {
260     binder().bindListener(typeMatcher, listener);
261   }
262 
263   /**
264    * @see Binder#bindListener(Matcher, ProvisionListener...)
265    * @since 4.0
266    */
bindListener( Matcher<? super Binding<?>> bindingMatcher, ProvisionListener... listeners)267   protected void bindListener(
268       Matcher<? super Binding<?>> bindingMatcher, ProvisionListener... listeners) {
269     binder().bindListener(bindingMatcher, listeners);
270   }
271 }
272