extensions/assistedinject/src/com/google/inject/assistedinject/AssistedConstructor.java

/**
 * Copyright (C) 2007 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.assistedinject;

import com.google.common.collect.Lists;
import com.google.inject.Inject;
import com.google.inject.TypeLiteral;

import java.lang.annotation.Annotation;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Type;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

/**
 * Internal respresentation of a constructor annotated with
 * {@link AssistedInject}
 * 
 * @author jmourits@google.com (Jerome Mourits)
 * @author jessewilson@google.com (Jesse Wilson)
 */
class AssistedConstructor<T> {

  private final Constructor<T> constructor;
  private final ParameterListKey assistedParameters;
  private final List<Parameter> allParameters;
  
  public static <T> AssistedConstructor<T> create(
      Constructor<T> constructor, List<TypeLiteral<?>> parameterTypes) {
    return new AssistedConstructor<T>(constructor, parameterTypes);
  }

  private AssistedConstructor(Constructor<T> constructor, List<TypeLiteral<?>> parameterTypes) {
    this.constructor = constructor;

    Annotation[][] annotations = constructor.getParameterAnnotations();

    List<Type> typeList = Lists.newArrayList();
    allParameters = new ArrayList<Parameter>();

    // categorize params as @Assisted or @Injected
    for (int i = 0; i < parameterTypes.size(); i++) {
      Parameter parameter = new Parameter(parameterTypes.get(i).getType(), annotations[i]);
      allParameters.add(parameter);
      if (parameter.isProvidedByFactory()) {
        typeList.add(parameter.getType());
      }
    }
    this.assistedParameters = new ParameterListKey(typeList);
  }
  
  /**
   * Returns the {@link ParameterListKey} for this constructor.  The
   * {@link ParameterListKey} is created from the ordered list of {@link Assisted}
   * constructor parameters.
   */
  public ParameterListKey getAssistedParameters() {
    return assistedParameters;
  }
  
  /**
   * Returns an ordered list of all constructor parameters (both
   * {@link Assisted} and {@link Inject}ed).
   */
  public List<Parameter> getAllParameters() {
    return allParameters;
  }

  public Set<Class<?>> getDeclaredExceptions() {
    return new HashSet<Class<?>>(Arrays.asList(constructor.getExceptionTypes()));
  }
  
  /**
   * Returns an instance of T, constructed using this constructor, with the
   * supplied arguments.
   */
  public T newInstance(Object[] args) throws Throwable {
    constructor.setAccessible(true);
    try {
      return constructor.newInstance(args);
    } catch (InvocationTargetException e) {
      throw e.getCause();
    }
  }
  
  @Override
  public String toString() {
    return constructor.toString();
  }
}