content: /*
   * Copyright 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 android.view.inspector;
  
  import android.annotation.NonNull;
  
  import java.util.ArrayList;
  import java.util.Collections;
  import java.util.HashSet;
  import java.util.List;
  import java.util.Objects;
  import java.util.Set;
  
  /**
   * Maps the values of an {@code int} property to sets of string for properties that encode flags.
   *
   * An {@link InspectionCompanion} may provide an instance of this class to a {@link PropertyMapper}
   * for flag values packed into primitive {@code int} properties.
   *
   * Each flag has a mask and a target value, for non-exclusive flags, the target can also be used as
   * the mask. A given integer value is compared against each flag to find what flags are active for
   * it by bitwise anding it with the mask and comparing the result against the target, that is,
   * {@code (value & mask) == target}.
   *
   * @see PropertyMapper#mapIntFlag(String, int, java.util.function.IntFunction)
   */
  public final class IntFlagMapping {
      private final List<Flag> mFlags = new ArrayList<>();
  
      /**
       * Get a set of the names of enabled flags for a given property value.
       *
       * @param value The value of the property
       * @return The names of the enabled flags, empty if no flags enabled
       */
      @NonNull
      public Set<String> get(int value) {
          final Set<String> enabledFlagNames = new HashSet<>(mFlags.size());
  
          for (Flag flag : mFlags) {
              if (flag.isEnabledFor(value)) {
                  enabledFlagNames.add(flag.mName);
              }
          }
  
          return Collections.unmodifiableSet(enabledFlagNames);
      }
  
      /**
       * Add a mutually exclusive flag to the map.
       *
       * @param mask The bit mask to compare to and with a value
       * @param target The target value to compare the masked value with
       * @param name The name of the flag to include if enabled
       */
      public void add(int mask, int target, @NonNull String name) {
          mFlags.add(new Flag(mask, target, name));
      }
  
      /**
       * Inner class that holds the name, mask, and target value of a flag
       */
      private static final class Flag {
          @NonNull private final String mName;
          private final int mTarget;
          private final int mMask;
  
          private Flag(int mask, int target, @NonNull String name) {
              mTarget = target;
              mMask = mask;
              mName = Objects.requireNonNull(name);
          }
  
          /**
           * Compare the supplied property value against the mask and target.
           *
           * @param value The value to check
           * @return True if this flag is enabled
           */
          private boolean isEnabledFor(int value) {
              return (value & mMask) == mTarget;
          }
      }
  }
  