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      1 /**
      2  * Copyright (C) 2012 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.inject.Binder;
     20 import com.google.inject.TypeLiteral;
     21 import com.google.inject.internal.Annotations;
     22 import com.google.inject.internal.Errors;
     23 import com.google.inject.spi.Message;
     24 
     25 import java.lang.annotation.Annotation;
     26 import java.lang.reflect.AnnotatedElement;
     27 import java.lang.reflect.Constructor;
     28 
     29 /**
     30  * Utilities for the throwing provider module.
     31  *
     32  * @author sameb (at) google.com (Sam Berlin)
     33  */
     34 class CheckedProvideUtils {
     35 
     36   private CheckedProvideUtils() {}
     37 
     38   private static final String CONSTRUCTOR_RULES =
     39       "Classes must have either one (and only one) constructor annotated with @ThrowingInject.";
     40 
     41   @SuppressWarnings("unchecked") // safe because it's a constructor of the typeLiteral
     42   static <T> Constructor<? extends T> findThrowingConstructor(
     43       TypeLiteral<? extends T> typeLiteral, Binder binder) {
     44 
     45     Class<?> rawType = typeLiteral.getRawType();
     46     Errors errors = new Errors(rawType);
     47     Constructor<?> cxtor = null;
     48     for (Constructor<?> constructor : rawType.getDeclaredConstructors()) {
     49       if (constructor.isAnnotationPresent(ThrowingInject.class)) {
     50         if (cxtor != null) {
     51           errors.addMessage("%s has more than one constructor annotated with @ThrowingInject. "
     52               + CONSTRUCTOR_RULES, rawType);
     53         }
     54 
     55         cxtor = constructor;
     56         Annotation misplacedBindingAnnotation = Annotations.findBindingAnnotation(
     57             errors, cxtor, ((AnnotatedElement) cxtor).getAnnotations());
     58         if (misplacedBindingAnnotation != null) {
     59           errors.misplacedBindingAnnotation(cxtor, misplacedBindingAnnotation);
     60         }
     61       }
     62     }
     63 
     64     if (cxtor == null) {
     65       errors.addMessage(
     66           "Could not find a suitable constructor in %s. " + CONSTRUCTOR_RULES, rawType);
     67     }
     68 
     69     for (Message msg : errors.getMessages()) {
     70       binder.addError(msg);
     71     }
     72     return (Constructor<? extends T>) cxtor;
     73   }
     74 
     75   /** Adds errors to the binder if the exceptions aren't valid. */
     76   static void validateExceptions(Binder binder,
     77       Iterable<TypeLiteral<?>> actualExceptionTypes,
     78       Iterable<Class<? extends Throwable>> expectedExceptionTypes,
     79       Class<? extends CheckedProvider> checkedProvider) {
     80     // Validate the exceptions in the method match the exceptions
     81     // in the CheckedProvider.
     82     for (TypeLiteral<?> exType : actualExceptionTypes) {
     83       Class<?> exActual = exType.getRawType();
     84       // Ignore runtime exceptions & errors.
     85       if (RuntimeException.class.isAssignableFrom(exActual)
     86           || Error.class.isAssignableFrom(exActual)) {
     87         continue;
     88       }
     89 
     90       boolean notAssignable = true;
     91       for (Class<? extends Throwable> exExpected : expectedExceptionTypes) {
     92         if (exExpected.isAssignableFrom(exActual)) {
     93           notAssignable = false;
     94           break;
     95         }
     96       }
     97       if (notAssignable) {
     98         binder.addError(
     99             "%s is not compatible with the exceptions (%s) declared in "
    100             + "the CheckedProvider interface (%s)",
    101             exActual, expectedExceptionTypes, checkedProvider);
    102       }
    103     }
    104   }
    105 
    106 }
    107