annotation/annotation/src/main/java/androidx/annotation/RestrictTo.java

/*
 * Copyright (C) 2016 The Android Open Source Project
 *
 * 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 androidx.annotation;

import static java.lang.annotation.ElementType.ANNOTATION_TYPE;
import static java.lang.annotation.ElementType.CONSTRUCTOR;
import static java.lang.annotation.ElementType.FIELD;
import static java.lang.annotation.ElementType.METHOD;
import static java.lang.annotation.ElementType.PACKAGE;
import static java.lang.annotation.ElementType.TYPE;
import static java.lang.annotation.RetentionPolicy.CLASS;

import java.lang.annotation.Retention;
import java.lang.annotation.Target;

/**
 * Denotes that the annotated element should only be accessed from within a
 * specific scope (as defined by {@link Scope}).
 * <p>
 * Example of restricting usage within a library (based on gradle group ID):
 * <pre><code>
 *   &#64;RestrictTo(GROUP_ID)
 *   public void resetPaddingToInitialValues() { ...
 * </code></pre>
 * Example of restricting usage to tests:
 * <pre><code>
 *   &#64;RestrictScope(TESTS)
 *   public abstract int getUserId();
 * </code></pre>
 * Example of restricting usage to subclasses:
 * <pre><code>
 *   &#64;RestrictScope(SUBCLASSES)
 *   public void onDrawForeground(Canvas canvas) { ...
 * </code></pre>
 */
@Retention(CLASS)
@Target({ANNOTATION_TYPE, TYPE, METHOD, CONSTRUCTOR, FIELD, PACKAGE})
public @interface RestrictTo {

    /**
     * The scope to which usage should be restricted.
     */
    Scope[] value();

    enum Scope {
        /**
         * Restrict usage to code within the same library (e.g. the same
         * gradle group ID and artifact ID).
         */
        LIBRARY,

        /**
         * Restrict usage to code within the same group of libraries.
         * This corresponds to the gradle group ID.
         */
        LIBRARY_GROUP,

        /**
         * Restrict usage to code within packages whose groups share
         * the same library group prefix up to the last ".", so for
         * example libraries foo.bar:lib1 and foo.baz:lib2 share
         * the prefix "foo." and so they can use each other's
         * apis that are restricted to this scope. Similarly for
         * com.foo.bar:lib1 and com.foo.baz:lib2 where they share
         * "com.foo.". Library com.bar.qux:lib3 however will not
         * be able to use the restricted api because it only
         * shares the prefix "com." and not all the way until the
         * last ".".
         */
        LIBRARY_GROUP_PREFIX,

        /**
         * Restrict usage to code within the same group ID (based on gradle
         * group ID). This is an alias for {@link #LIBRARY_GROUP_PREFIX}.
         *
         * @deprecated Use {@link #LIBRARY_GROUP_PREFIX} instead
         */
        @Deprecated
        GROUP_ID,

        /**
         * Restrict usage to tests.
         */
        TESTS,

        /**
         * Restrict usage to subclasses of the enclosing class.
         * <p>
         * <strong>Note:</strong> This scope should not be used to annotate
         * packages.
         */
        SUBCLASSES,
    }
}