com.facebook.buck.rules.modern.CustomBehaviorUtils.java Source code

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Here is the source code for com.facebook.buck.rules.modern.CustomBehaviorUtils.java

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/*
 * Copyright 2018-present Facebook, 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.facebook.buck.rules.modern;

import com.facebook.buck.core.rules.modern.annotations.CustomClassBehavior;
import com.facebook.buck.core.rules.modern.annotations.CustomClassBehaviorTag;
import com.facebook.buck.core.rules.modern.annotations.CustomFieldBehavior;
import com.facebook.buck.core.rules.modern.annotations.CustomFieldBehaviorTag;
import com.facebook.buck.util.RichStream;
import com.google.common.base.Preconditions;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import java.util.List;
import java.util.Optional;
import java.util.stream.Collectors;

/** Utilities for dealing with CustomFieldBehavior and CustomClassBehavior. */
public class CustomBehaviorUtils {
    /** Returns the class behavior of the requested type (if there is one). */
    public static <C extends CustomClassBehaviorTag> Optional<CustomClassBehaviorTag> getBehavior(Class<?> clazz,
            Class<C> behaviorClass) {
        CustomClassBehavior behavior = clazz.getAnnotation(CustomClassBehavior.class);
        if (behavior == null) {
            return Optional.empty();
        }

        List<Class<? extends CustomClassBehaviorTag>> matches = RichStream.from(behavior.value())
                .filter(behaviorClass::isAssignableFrom).collect(Collectors.toList());
        if (matches.isEmpty()) {
            return Optional.empty();
        }
        Preconditions.checkState(matches.size() == 1);
        Class<? extends CustomClassBehaviorTag> tag = matches.get(0);

        try {
            Constructor<? extends CustomClassBehaviorTag> constructor = tag.getDeclaredConstructor();
            constructor.setAccessible(true);
            return Optional.of(constructor.newInstance());
        } catch (NoSuchMethodException | IllegalAccessException | InstantiationException
                | InvocationTargetException e) {
            throw new RuntimeException(e);
        }
    }

    /** Returns the field behavior behavior of the requested type (if there is one). */
    public static <U extends CustomFieldBehaviorTag> Optional<U> get(Optional<CustomFieldBehavior> behavior,
            Class<U> behaviorClass) {
        return behavior.flatMap(b -> get(b, behaviorClass));
    }

    /** Returns the field behavior behavior of the requested type (if there is one). */
    public static <U extends CustomFieldBehaviorTag> Optional<U> get(CustomFieldBehavior behavior,
            Class<U> behaviorClass) {
        if (behavior == null) {
            return Optional.empty();
        }

        List<Class<? extends CustomFieldBehaviorTag>> matches = RichStream.from(behavior.value())
                .filter(behaviorClass::isAssignableFrom).collect(Collectors.toList());
        if (matches.isEmpty()) {
            return Optional.empty();
        }
        Preconditions.checkState(matches.size() == 1);
        @SuppressWarnings("unchecked")
        Class<? extends U> tag = (Class<? extends U>) matches.get(0);

        try {
            Constructor<? extends U> constructor = tag.getDeclaredConstructor();
            constructor.setAccessible(true);
            return Optional.of(constructor.newInstance());
        } catch (NoSuchMethodException | IllegalAccessException | InstantiationException
                | InvocationTargetException e) {
            throw new RuntimeException(e);
        }
    }
}