content: /*
   * Copyright (C) 2018 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 com.android.internal.inputmethod;
  
  import android.annotation.AnyThread;
  import android.annotation.NonNull;
  import android.annotation.Nullable;
  import android.os.IBinder;
  
  import com.android.internal.annotations.GuardedBy;
  
  import java.lang.ref.WeakReference;
  import java.util.WeakHashMap;
  
  /**
   * A weak-reference-based mapper from IME token to {@link InputMethodPrivilegedOperations} that is
   * used only to support deprecated IME APIs in {@link android.view.inputmethod.InputMethodManager}.
   *
   * <p>This class is designed to be used as a per-process global registry.</p>
   */
  public final class InputMethodPrivilegedOperationsRegistry {
      private InputMethodPrivilegedOperationsRegistry() {
          // Not intended to be instantiated.
      }
  
      private static final Object sLock = new Object();
  
      @Nullable
      @GuardedBy("sLock")
      private static WeakHashMap<IBinder, WeakReference<InputMethodPrivilegedOperations>> sRegistry;
  
      @Nullable
      private static InputMethodPrivilegedOperations sNop;
  
      @NonNull
      @AnyThread
      private static InputMethodPrivilegedOperations getNopOps() {
          // Strict thread-safety is not necessary because temporarily creating multiple nop instance
          // is basically harmless
          if (sNop == null) {
              sNop = new InputMethodPrivilegedOperations();
          }
          return sNop;
      }
  
      /**
       * Put a new entry to the registry.
       *
       * <p>Note: {@link InputMethodPrivilegedOperationsRegistry} does not hold strong reference to
       * {@code token} and {@code ops}.  The caller must be responsible for holding strong references
       * to those objects, that is until {@link android.inputmethodservice.InputMethodService} is
       * destroyed.</p>
       *
       * @param token IME token
       * @param ops {@link InputMethodPrivilegedOperations} to be associated with the given IME token
       */
      @AnyThread
      public static void put(IBinder token, InputMethodPrivilegedOperations ops) {
          synchronized (sLock) {
              if (sRegistry == null) {
                  sRegistry = new WeakHashMap<>();
              }
              final WeakReference<InputMethodPrivilegedOperations> previousOps =
                      sRegistry.put(token, new WeakReference<>(ops));
              if (previousOps != null) {
                  throw new IllegalStateException(previousOps.get() + " is already registered for "
                          + " this token=" + token + " newOps=" + ops);
              }
          }
      }
  
      /**
       * Get a {@link InputMethodPrivilegedOperations} from the given IME token.  If it is not
       * available, return a fake instance that does nothing except for showing warning messages.
       *
       * @param token IME token
       * @return real {@link InputMethodPrivilegedOperations} object if {@code token} is still valid.
       *         Otherwise a fake instance of {@link InputMethodPrivilegedOperations} hat does nothing
       *         except for showing warning messages
       */
      @NonNull
      @AnyThread
      public static InputMethodPrivilegedOperations get(IBinder token) {
          synchronized (sLock) {
              if (sRegistry == null) {
                  return getNopOps();
              }
              final WeakReference<InputMethodPrivilegedOperations> wrapperRef = sRegistry.get(token);
              if (wrapperRef == null) {
                  return getNopOps();
              }
              final InputMethodPrivilegedOperations wrapper = wrapperRef.get();
              if (wrapper == null) {
                  return getNopOps();
              }
              return wrapper;
          }
      }
  
      /**
       * Explicitly removes the specified entry.
       *
       * <p>Note: Calling this method is optional. In general, {@link WeakHashMap} and
       * {@link WeakReference} guarantee that the entry will be removed after specified binder proxies
       * are garbage collected.</p>
       *
       * @param token IME token to be removed.
       */
      @AnyThread
      public static void remove(IBinder token) {
          synchronized (sLock) {
              if (sRegistry == null) {
                  return;
              }
              sRegistry.remove(token);
              if (sRegistry.isEmpty()) {
                  sRegistry = null;
              }
          }
      }
  
      /**
       * Check the given IME token registration status.
       *
       * @param token IME token
       * @return {@code true} when the IME token has already registered
       *         {@link InputMethodPrivilegedOperations}, {@code false} otherwise.
       */
      @AnyThread
      public static boolean isRegistered(IBinder token) {
          synchronized (sLock) {
              if (sRegistry == null) {
                  return false;
              }
              return sRegistry.containsKey(token);
          }
      }
  }
  