001/*
002 * Copyright (C) 2012 The Guava Authors
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
005 * in compliance with the License. You may obtain a copy of the License at
006 *
007 * http://www.apache.org/licenses/LICENSE-2.0
008 *
009 * Unless required by applicable law or agreed to in writing, software distributed under the License
010 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
011 * or implied. See the License for the specific language governing permissions and limitations under
012 * the License.
013 */
014
015package com.google.common.reflect;
016
017import static com.google.common.base.Preconditions.checkNotNull;
018
019import com.google.common.annotations.Beta;
020import com.google.common.collect.FluentIterable;
021import com.google.common.collect.ImmutableList;
022import java.lang.annotation.Annotation;
023import java.lang.reflect.AnnotatedElement;
024import java.lang.reflect.AnnotatedType;
025import javax.annotation.CheckForNull;
026import org.checkerframework.checker.nullness.qual.Nullable;
027
028/**
029 * Represents a method or constructor parameter.
030 *
031 * <p><b>Note:</b> Since Java 8 introduced {@link java.lang.reflect.Parameter} to represent method
032 * and constructor parameters, this class is no longer necessary. We intend to deprecate it in a
033 * future version.
034 *
035 * @author Ben Yu
036 * @since 14.0
037 */
038@Beta
039@ElementTypesAreNonnullByDefault
040public final class Parameter implements AnnotatedElement {
041
042  private final Invokable<?, ?> declaration;
043  private final int position;
044  private final TypeToken<?> type;
045  private final ImmutableList<Annotation> annotations;
046  private final AnnotatedType annotatedType;
047
048  Parameter(
049      Invokable<?, ?> declaration,
050      int position,
051      TypeToken<?> type,
052      Annotation[] annotations,
053      AnnotatedType annotatedType) {
054    this.declaration = declaration;
055    this.position = position;
056    this.type = type;
057    this.annotations = ImmutableList.copyOf(annotations);
058    this.annotatedType = annotatedType;
059  }
060
061  /** Returns the type of the parameter. */
062  public TypeToken<?> getType() {
063    return type;
064  }
065
066  /** Returns the {@link Invokable} that declares this parameter. */
067  public Invokable<?, ?> getDeclaringInvokable() {
068    return declaration;
069  }
070
071  @Override
072  public boolean isAnnotationPresent(Class<? extends Annotation> annotationType) {
073    return getAnnotation(annotationType) != null;
074  }
075
076  @Override
077  @CheckForNull
078  public <A extends Annotation> A getAnnotation(Class<A> annotationType) {
079    checkNotNull(annotationType);
080    for (Annotation annotation : annotations) {
081      if (annotationType.isInstance(annotation)) {
082        return annotationType.cast(annotation);
083      }
084    }
085    return null;
086  }
087
088  @Override
089  public Annotation[] getAnnotations() {
090    return getDeclaredAnnotations();
091  }
092
093  /** @since 18.0 */
094  // @Override on JDK8
095  @Override
096  public <A extends Annotation> A[] getAnnotationsByType(Class<A> annotationType) {
097    return getDeclaredAnnotationsByType(annotationType);
098  }
099
100  /** @since 18.0 */
101  // @Override on JDK8
102  @Override
103  public Annotation[] getDeclaredAnnotations() {
104    return annotations.toArray(new Annotation[0]);
105  }
106
107  /** @since 18.0 */
108  // @Override on JDK8
109  @Override
110  @CheckForNull
111  public <A extends Annotation> A getDeclaredAnnotation(Class<A> annotationType) {
112    checkNotNull(annotationType);
113    return FluentIterable.from(annotations).filter(annotationType).first().orNull();
114  }
115
116  /** @since 18.0 */
117  // @Override on JDK8
118  @Override
119  public <A extends Annotation> A[] getDeclaredAnnotationsByType(Class<A> annotationType) {
120    @Nullable
121    A[] result = FluentIterable.from(annotations).filter(annotationType).toArray(annotationType);
122    @SuppressWarnings("nullness") // safe because the input list contains no nulls
123    A[] cast = (A[]) result;
124    return cast;
125  }
126
127  /** @since 25.1 */
128  // @Override on JDK8
129  public AnnotatedType getAnnotatedType() {
130    return annotatedType;
131  }
132
133  @Override
134  public boolean equals(@CheckForNull Object obj) {
135    if (obj instanceof Parameter) {
136      Parameter that = (Parameter) obj;
137      return position == that.position && declaration.equals(that.declaration);
138    }
139    return false;
140  }
141
142  @Override
143  public int hashCode() {
144    return position;
145  }
146
147  @Override
148  public String toString() {
149    return type + " arg" + position;
150  }
151}