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/*
* 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;
}
}
}
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