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Java example source code file (AbstractBindingProcessor.java)

This example Java source code file (AbstractBindingProcessor.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

abstractbindingprocessor, bindingimpl, class, exposedbindingimpl, injectorimpl, key, object, processedbindingdata, processor, runnable, set, state, untargettedbindingimpl, util

The AbstractBindingProcessor.java Java example source code

/**
 * Copyright (C) 2011 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.inject.internal;

import com.google.common.collect.ImmutableSet;
import com.google.inject.AbstractModule;
import com.google.inject.Binder;
import com.google.inject.Binding;
import com.google.inject.Injector;
import com.google.inject.Key;
import com.google.inject.MembersInjector;
import com.google.inject.Module;
import com.google.inject.Provider;
import com.google.inject.Scope;
import com.google.inject.Stage;
import com.google.inject.TypeLiteral;
import com.google.inject.spi.DefaultBindingTargetVisitor;

import java.util.Set;

/**
 * Guarantees that processing of Binding elements happens in a sane way.
 * 
 * @author sameb@google.com (Sam Berlin)
 */
abstract class AbstractBindingProcessor extends AbstractProcessor {

  // It's unfortunate that we have to maintain a blacklist of specific
  // classes, but we can't easily block the whole package because of
  // all our unit tests.
  private static final Set<Class FORBIDDEN_TYPES = ImmutableSet.>of(
      AbstractModule.class,
      Binder.class,
      Binding.class,
      Injector.class,
      Key.class,
      MembersInjector.class,
      Module.class,
      Provider.class,
      Scope.class,
      Stage.class,
      TypeLiteral.class);
  
  protected final ProcessedBindingData bindingData;
  
  AbstractBindingProcessor(Errors errors, ProcessedBindingData bindingData) {
    super(errors);
    this.bindingData = bindingData;
  }

  protected <T> UntargettedBindingImpl invalidBinding(
      InjectorImpl injector, Key<T> key, Object source) {
    return new UntargettedBindingImpl<T>(injector, key, source);
  }
  
  protected void putBinding(BindingImpl<?> binding) {
    Key<?> key = binding.getKey();

    Class<?> rawType = key.getTypeLiteral().getRawType();
    if (FORBIDDEN_TYPES.contains(rawType)) {
      errors.cannotBindToGuiceType(rawType.getSimpleName());
      return;
    }

    BindingImpl<?> original = injector.getExistingBinding(key);
    if (original != null) {
      // If it failed because of an explicit duplicate binding...
      if (injector.state.getExplicitBinding(key) != null) {
        try {
          if(!isOkayDuplicate(original, binding, injector.state)) {
            errors.bindingAlreadySet(key, original.getSource());
            return;
          }
        } catch(Throwable t) {
          errors.errorCheckingDuplicateBinding(key, original.getSource(), t);
          return;
        }
      } else {
        // Otherwise, it failed because of a duplicate JIT binding
        // in the parent
        errors.jitBindingAlreadySet(key);
        return;
      }
    }

    // prevent the parent from creating a JIT binding for this key
    injector.state.parent().blacklist(key, injector.state, binding.getSource());
    injector.state.putBinding(key, binding);
  }

  /**
   * We tolerate duplicate bindings if one exposes the other or if the two bindings
   * are considered duplicates (see {@link Bindings#areDuplicates(BindingImpl, BindingImpl)}.
   *
   * @param original the binding in the parent injector (candidate for an exposing binding)
   * @param binding the binding to check (candidate for the exposed binding)
   */
  private boolean isOkayDuplicate(BindingImpl<?> original, BindingImpl binding, State state) {
    if (original instanceof ExposedBindingImpl) {
      ExposedBindingImpl exposed = (ExposedBindingImpl) original;
      InjectorImpl exposedFrom = (InjectorImpl) exposed.getPrivateElements().getInjector();
      return (exposedFrom == binding.getInjector());
    } else {
      original = (BindingImpl<?>)state.getExplicitBindingsThisLevel().get(binding.getKey());
      // If no original at this level, the original was on a parent, and we don't
      // allow deduplication between parents & children.
      if(original == null) {
        return false;
      } else {
        return original.equals(binding);
      }
    }
  }
  
  private <T> void validateKey(Object source, Key key) {
    Annotations.checkForMisplacedScopeAnnotations(
        key.getTypeLiteral().getRawType(), source, errors);
  }
  
  /** 
   * Processor for visiting bindings.  Each overriden method that wants to
   * actually process the binding should call prepareBinding first.
   */
  abstract class Processor<T, V> extends DefaultBindingTargetVisitor {
    final Object source;
    final Key<T> key;
    final Class<? super T> rawType;
    Scoping scoping;
    
    Processor(BindingImpl<T> binding) {
      source = binding.getSource();
      key = binding.getKey();
      rawType = key.getTypeLiteral().getRawType();
      scoping = binding.getScoping();
    }
    
    protected void prepareBinding() {      
      validateKey(source, key);
      scoping = Scoping.makeInjectable(scoping, injector, errors);
    }

    protected void scheduleInitialization(final BindingImpl<?> binding) {
      bindingData.addUninitializedBinding(new Runnable() {
        public void run() {
          try {
            binding.getInjector().initializeBinding(binding, errors.withSource(source));
          } catch (ErrorsException e) {
            errors.merge(e.getErrors());
          }
        }
      });
    }
  }
}

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