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      1 /*
      2  * Copyright (C) 2015 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 package com.google.inject.daggeradapter;
     17 
     18 import com.google.common.collect.ImmutableSet;
     19 import com.google.inject.Binder;
     20 import com.google.inject.Key;
     21 import com.google.inject.internal.UniqueAnnotations;
     22 import com.google.inject.multibindings.Multibinder;
     23 import com.google.inject.spi.InjectionPoint;
     24 import com.google.inject.spi.ModuleAnnotatedMethodScanner;
     25 import dagger.Provides;
     26 import dagger.Provides.Type;
     27 import dagger.multibindings.ElementsIntoSet;
     28 import dagger.multibindings.IntoMap;
     29 import dagger.multibindings.IntoSet;
     30 import java.lang.annotation.Annotation;
     31 import java.lang.reflect.Method;
     32 import java.util.Set;
     33 
     34 /**
     35  * A scanner to process provider methods on Dagger modules.
     36  *
     37  * @author cgruber (at) google.com (Christian Gruber)
     38  */
     39 final class DaggerMethodScanner extends ModuleAnnotatedMethodScanner {
     40   static final DaggerMethodScanner INSTANCE = new DaggerMethodScanner();
     41   private static final ImmutableSet<Class<Provides>> ANNOTATIONS =
     42       ImmutableSet.of(dagger.Provides.class);
     43 
     44   @Override
     45   public Set<? extends Class<? extends Annotation>> annotationClasses() {
     46     return ANNOTATIONS;
     47   }
     48 
     49   @Override
     50   public <T> Key<T> prepareMethod(
     51       Binder binder, Annotation rawAnnotation, Key<T> key, InjectionPoint injectionPoint) {
     52     Method providesMethod = (Method) injectionPoint.getMember();
     53     Provides annotation = (Provides) rawAnnotation;
     54     if (providesMethod.isAnnotationPresent(IntoSet.class)) {
     55       return processSetBinding(binder, key);
     56     } else if (providesMethod.isAnnotationPresent(ElementsIntoSet.class)) {
     57       binder.addError("@ElementsIntoSet contributions are not suppored by Guice.", providesMethod);
     58       return key;
     59     } else if (providesMethod.isAnnotationPresent(IntoMap.class)) {
     60       /* TODO(cgruber) implement map bindings */
     61       binder.addError("Map bindings are not yet supported.");
     62       return key;
     63     }
     64 
     65     switch (annotation.type()) {
     66       case UNIQUE:
     67         return key;
     68       case SET:
     69         return processSetBinding(binder, key);
     70       case SET_VALUES:
     71         binder.addError(
     72             Type.SET_VALUES.name() + " contributions are not supported by Guice.", providesMethod);
     73         return key;
     74       default:
     75         binder.addError("Unknown @Provides type " + annotation.type() + ".", providesMethod);
     76         return key;
     77     }
     78   }
     79 
     80   private static <T> Key<T> processSetBinding(Binder binder, Key<T> key) {
     81     Annotation annotation = key.getAnnotation();
     82     Multibinder<T> setBinder =
     83         (annotation != null)
     84             ? Multibinder.newSetBinder(binder, key.getTypeLiteral(), annotation)
     85             : Multibinder.newSetBinder(binder, key.getTypeLiteral());
     86     Key<T> newKey = Key.get(key.getTypeLiteral(), UniqueAnnotations.create());
     87     setBinder.addBinding().to(newKey);
     88     return newKey;
     89   }
     90 
     91   private DaggerMethodScanner() {}
     92 }
     93