com.google.common.reflect.Parameter.java Source code

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Here is the source code for com.google.common.reflect.Parameter.java

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/*
 * Copyright (C) 2012 The Guava Authors
 *
 * 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.common.reflect;

import static com.google.common.base.Preconditions.checkNotNull;

import com.google.common.annotations.Beta;
import com.google.common.collect.FluentIterable;
import com.google.common.collect.ImmutableList;

import java.lang.annotation.Annotation;
import java.lang.reflect.AnnotatedElement;

import javax.annotation.Nullable;

/**
 * Represents a method or constructor parameter.
 *
 * @author Ben Yu
 * @since 14.0
 */
@Beta
public final class Parameter implements AnnotatedElement {

    private final Invokable<?, ?> declaration;
    private final int position;
    private final TypeToken<?> type;
    private final ImmutableList<Annotation> annotations;

    Parameter(Invokable<?, ?> declaration, int position, TypeToken<?> type, Annotation[] annotations) {
        this.declaration = declaration;
        this.position = position;
        this.type = type;
        this.annotations = ImmutableList.copyOf(annotations);
    }

    /** Returns the type of the parameter. */
    public TypeToken<?> getType() {
        return type;
    }

    /** Returns the {@link Invokable} that declares this parameter. */
    public Invokable<?, ?> getDeclaringInvokable() {
        return declaration;
    }

    @Override
    public boolean isAnnotationPresent(Class<? extends Annotation> annotationType) {
        return getAnnotation(annotationType) != null;
    }

    @Override
    @Nullable
    public <A extends Annotation> A getAnnotation(Class<A> annotationType) {
        checkNotNull(annotationType);
        for (Annotation annotation : annotations) {
            if (annotationType.isInstance(annotation)) {
                return annotationType.cast(annotation);
            }
        }
        return null;
    }

    @Override
    public Annotation[] getAnnotations() {
        return getDeclaredAnnotations();
    }

    /**
     * @since 18.0
     */
    // @Override on JDK8
    public <A extends Annotation> A[] getAnnotationsByType(Class<A> annotationType) {
        return getDeclaredAnnotationsByType(annotationType);
    }

    /**
     * @since 18.0
     */
    // @Override on JDK8
    @Override
    public Annotation[] getDeclaredAnnotations() {
        return annotations.toArray(new Annotation[annotations.size()]);
    }

    /**
     * @since 18.0
     */
    // @Override on JDK8
    @Nullable
    public <A extends Annotation> A getDeclaredAnnotation(Class<A> annotationType) {
        checkNotNull(annotationType);
        return FluentIterable.from(annotations).filter(annotationType).first().orNull();
    }

    /**
     * @since 18.0
     */
    // @Override on JDK8
    public <A extends Annotation> A[] getDeclaredAnnotationsByType(Class<A> annotationType) {
        return FluentIterable.from(annotations).filter(annotationType).toArray(annotationType);
    }

    @Override
    public boolean equals(@Nullable Object obj) {
        if (obj instanceof Parameter) {
            Parameter that = (Parameter) obj;
            return position == that.position && declaration.equals(that.declaration);
        }
        return false;
    }

    @Override
    public int hashCode() {
        return position;
    }

    @Override
    public String toString() {
        return type + " arg" + position;
    }
}