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      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.throwingproviders;
     18 
     19 import com.google.common.collect.ImmutableSet;
     20 import com.google.inject.Binder;
     21 import com.google.inject.Exposed;
     22 import com.google.inject.Key;
     23 import com.google.inject.PrivateBinder;
     24 import com.google.inject.Provider;
     25 import com.google.inject.TypeLiteral;
     26 import com.google.inject.binder.ScopedBindingBuilder;
     27 import com.google.inject.internal.util.StackTraceElements;
     28 import com.google.inject.spi.Dependency;
     29 import com.google.inject.spi.HasDependencies;
     30 import com.google.inject.throwingproviders.ThrowingProviderBinder.SecondaryBinder;
     31 
     32 import java.lang.annotation.Annotation;
     33 import java.lang.reflect.InvocationTargetException;
     34 import java.lang.reflect.Method;
     35 import java.util.List;
     36 import java.util.Set;
     37 
     38 /**
     39  * A provider that invokes a method and returns its result.
     40  *
     41  * @author sameb (at) google.com (Sam Berlin)
     42  */
     43 class CheckedProviderMethod<T> implements CheckedProvider<T>, HasDependencies {
     44   private final Key<T> key;
     45   private final Class<? extends Annotation> scopeAnnotation;
     46   private final Object instance;
     47   private final Method method;
     48   private final ImmutableSet<Dependency<?>> dependencies;
     49   private final List<Provider<?>> parameterProviders;
     50   private final boolean exposed;
     51   private final Class<? extends CheckedProvider> checkedProvider;
     52   private final List<TypeLiteral<?>> exceptionTypes;
     53   private final boolean scopeExceptions;
     54 
     55   CheckedProviderMethod(
     56       Key<T> key,
     57       Method method,
     58       Object instance,
     59       ImmutableSet<Dependency<?>> dependencies,
     60       List<Provider<?>> parameterProviders,
     61       Class<? extends Annotation> scopeAnnotation,
     62       Class<? extends CheckedProvider> checkedProvider,
     63       List<TypeLiteral<?>> exceptionTypes,
     64       boolean scopeExceptions) {
     65     this.key = key;
     66     this.scopeAnnotation = scopeAnnotation;
     67     this.instance = instance;
     68     this.dependencies = dependencies;
     69     this.method = method;
     70     this.parameterProviders = parameterProviders;
     71     this.exposed = method.isAnnotationPresent(Exposed.class);
     72     this.checkedProvider = checkedProvider;
     73     this.exceptionTypes = exceptionTypes;
     74     this.scopeExceptions = scopeExceptions;
     75 
     76     method.setAccessible(true);
     77   }
     78 
     79   void configure(Binder binder) {
     80     binder = binder.withSource(method);
     81 
     82     SecondaryBinder<?, ?> sbinder =
     83         ThrowingProviderBinder.create(binder)
     84           .bind(checkedProvider, key.getTypeLiteral());
     85     if(key.getAnnotation() != null) {
     86       sbinder = sbinder.annotatedWith(key.getAnnotation());
     87     } else if(key.getAnnotationType() != null) {
     88       sbinder = sbinder.annotatedWith(key.getAnnotationType());
     89     }
     90     sbinder.scopeExceptions(scopeExceptions);
     91     ScopedBindingBuilder sbbuilder = sbinder.toProviderMethod(this);
     92     if(scopeAnnotation != null) {
     93       sbbuilder.in(scopeAnnotation);
     94     }
     95 
     96     if (exposed) {
     97       // the cast is safe 'cause the only binder we have implements PrivateBinder. If there's a
     98       // misplaced @Exposed, calling this will add an error to the binder's error queue
     99       ((PrivateBinder) binder).expose(sbinder.getKey());
    100     }
    101 
    102     CheckedProvideUtils.validateExceptions(
    103         binder, exceptionTypes, sbinder.getExceptionTypes(), checkedProvider);
    104   }
    105 
    106   public T get() throws Exception {
    107     Object[] parameters = new Object[parameterProviders.size()];
    108     for (int i = 0; i < parameters.length; i++) {
    109       parameters[i] = parameterProviders.get(i).get();
    110     }
    111 
    112     try {
    113       // We know this cast is safe becase T is the method's return type.
    114       @SuppressWarnings({ "unchecked", "UnnecessaryLocalVariable" })
    115       T result = (T) method.invoke(instance, parameters);
    116       return result;
    117     } catch (IllegalAccessException e) {
    118       throw new AssertionError(e);
    119     } catch (InvocationTargetException e) {
    120       Throwable t = e.getCause();
    121       if(t instanceof Exception) {
    122         throw (Exception)t;
    123       } else if(t instanceof Error) {
    124         throw (Error)t;
    125       } else {
    126         throw new IllegalStateException(t);
    127       }
    128     }
    129   }
    130 
    131   public Set<Dependency<?>> getDependencies() {
    132     return dependencies;
    133   }
    134 
    135   @Override public String toString() {
    136     return "@CheckedProvides " + StackTraceElements.forMember(method);
    137   }
    138 }
    139