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/*
* Copyright (C) 2006 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.util;
import android.annotation.Nullable;
import android.compat.annotation.UnsupportedAppUsage;
import com.android.internal.util.ArrayUtils;
import com.android.internal.util.GrowingArrayUtils;
import libcore.util.EmptyArray;
/**
* SparseBooleanArrays map integers to booleans.
* Unlike a normal array of booleans
* there can be gaps in the indices. It is intended to be more memory efficient
* than using a HashMap to map Integers to Booleans, both because it avoids
* auto-boxing keys and values and its data structure doesn't rely on an extra entry object
* for each mapping.
*
* Note that this container keeps its mappings in an array data structure,
* using a binary search to find keys. The implementation is not intended to be appropriate for
* data structures
* that may contain large numbers of items. It is generally slower than a traditional
* HashMap, since lookups require a binary search and adds and removes require inserting
* and deleting entries in the array. For containers holding up to hundreds of items,
* the performance difference is not significant, less than 50%.
*
* It is possible to iterate over the items in this container using
* {@link #keyAt(int)} and {@link #valueAt(int)}. Iterating over the keys using
* keyAt(int) with ascending values of the index will return the
* keys in ascending order, or the values corresponding to the keys in ascending
* order in the case of valueAt(int).
*/
public class SparseBooleanArray implements Cloneable {
/**
* Creates a new SparseBooleanArray containing no mappings.
*/
public SparseBooleanArray() {
this(10);
}
/**
* Creates a new SparseBooleanArray containing no mappings that will not
* require any additional memory allocation to store the specified
* number of mappings. If you supply an initial capacity of 0, the
* sparse array will be initialized with a light-weight representation
* not requiring any additional array allocations.
*/
public SparseBooleanArray(int initialCapacity) {
if (initialCapacity == 0) {
mKeys = EmptyArray.INT;
mValues = EmptyArray.BOOLEAN;
} else {
mKeys = ArrayUtils.newUnpaddedIntArray(initialCapacity);
mValues = new boolean[mKeys.length];
}
mSize = 0;
}
@Override
public SparseBooleanArray clone() {
SparseBooleanArray clone = null;
try {
clone = (SparseBooleanArray) super.clone();
clone.mKeys = mKeys.clone();
clone.mValues = mValues.clone();
} catch (CloneNotSupportedException cnse) {
/* ignore */
}
return clone;
}
/**
* Gets the boolean mapped from the specified key, or false
* if no such mapping has been made.
*/
public boolean get(int key) {
return get(key, false);
}
/**
* Gets the boolean mapped from the specified key, or the specified value
* if no such mapping has been made.
*/
public boolean get(int key, boolean valueIfKeyNotFound) {
int i = ContainerHelpers.binarySearch(mKeys, mSize, key);
if (i < 0) {
return valueIfKeyNotFound;
} else {
return mValues[i];
}
}
/**
* Removes the mapping from the specified key, if there was any.
*/
public void delete(int key) {
int i = ContainerHelpers.binarySearch(mKeys, mSize, key);
if (i >= 0) {
System.arraycopy(mKeys, i + 1, mKeys, i, mSize - (i + 1));
System.arraycopy(mValues, i + 1, mValues, i, mSize - (i + 1));
mSize--;
}
}
/**
* Removes the mapping at the specified index.
*
* For indices outside of the range {@code 0...size()-1}, the behavior is undefined.
*/
public void removeAt(int index) {
System.arraycopy(mKeys, index + 1, mKeys, index, mSize - (index + 1));
System.arraycopy(mValues, index + 1, mValues, index, mSize - (index + 1));
mSize--;
}
/**
* Adds a mapping from the specified key to the specified value,
* replacing the previous mapping from the specified key if there
* was one.
*/
public void put(int key, boolean value) {
int i = ContainerHelpers.binarySearch(mKeys, mSize, key);
if (i >= 0) {
mValues[i] = value;
} else {
i = ~i;
mKeys = GrowingArrayUtils.insert(mKeys, mSize, i, key);
mValues = GrowingArrayUtils.insert(mValues, mSize, i, value);
mSize++;
}
}
/**
* Returns the number of key-value mappings that this SparseBooleanArray
* currently stores.
*/
public int size() {
return mSize;
}
/**
* Given an index in the range 0...size()-1, returns
* the key from the indexth key-value mapping that this
* SparseBooleanArray stores.
*
*
The keys corresponding to indices in ascending order are guaranteed to
* be in ascending order, e.g., keyAt(0) will return the
* smallest key and keyAt(size()-1) will return the largest
* key.
*
* For indices outside of the range 0...size()-1, the behavior is undefined for
* apps targeting {@link android.os.Build.VERSION_CODES#P} and earlier, and an
* {@link ArrayIndexOutOfBoundsException} is thrown for apps targeting
* {@link android.os.Build.VERSION_CODES#Q} and later.
*/
public int keyAt(int index) {
if (index >= mSize && UtilConfig.sThrowExceptionForUpperArrayOutOfBounds) {
// The array might be slightly bigger than mSize, in which case, indexing won't fail.
// Check if exception should be thrown outside of the critical path.
throw new ArrayIndexOutOfBoundsException(index);
}
return mKeys[index];
}
/**
* Given an index in the range 0...size()-1, returns
* the value from the indexth key-value mapping that this
* SparseBooleanArray stores.
*
* The values corresponding to indices in ascending order are guaranteed
* to be associated with keys in ascending order, e.g.,
* valueAt(0) will return the value associated with the
* smallest key and valueAt(size()-1) will return the value
* associated with the largest key.
*
* For indices outside of the range 0...size()-1, the behavior is undefined for
* apps targeting {@link android.os.Build.VERSION_CODES#P} and earlier, and an
* {@link ArrayIndexOutOfBoundsException} is thrown for apps targeting
* {@link android.os.Build.VERSION_CODES#Q} and later.
*/
public boolean valueAt(int index) {
if (index >= mSize && UtilConfig.sThrowExceptionForUpperArrayOutOfBounds) {
// The array might be slightly bigger than mSize, in which case, indexing won't fail.
// Check if exception should be thrown outside of the critical path.
throw new ArrayIndexOutOfBoundsException(index);
}
return mValues[index];
}
/**
* Directly set the value at a particular index.
*
* For indices outside of the range 0...size()-1, the behavior is undefined for
* apps targeting {@link android.os.Build.VERSION_CODES#P} and earlier, and an
* {@link ArrayIndexOutOfBoundsException} is thrown for apps targeting
* {@link android.os.Build.VERSION_CODES#Q} and later.
*/
public void setValueAt(int index, boolean value) {
if (index >= mSize && UtilConfig.sThrowExceptionForUpperArrayOutOfBounds) {
// The array might be slightly bigger than mSize, in which case, indexing won't fail.
// Check if exception should be thrown outside of the critical path.
throw new ArrayIndexOutOfBoundsException(index);
}
mValues[index] = value;
}
/** @hide */
public void setKeyAt(int index, int key) {
if (index >= mSize) {
// The array might be slightly bigger than mSize, in which case, indexing won't fail.
throw new ArrayIndexOutOfBoundsException(index);
}
mKeys[index] = key;
}
/**
* Returns the index for which {@link #keyAt} would return the
* specified key, or a negative number if the specified
* key is not mapped.
*/
public int indexOfKey(int key) {
return ContainerHelpers.binarySearch(mKeys, mSize, key);
}
/**
* Returns an index for which {@link #valueAt} would return the
* specified key, or a negative number if no keys map to the
* specified value.
* Beware that this is a linear search, unlike lookups by key,
* and that multiple keys can map to the same value and this will
* find only one of them.
*/
public int indexOfValue(boolean value) {
for (int i = 0; i < mSize; i++)
if (mValues[i] == value)
return i;
return -1;
}
/**
* Removes all key-value mappings from this SparseBooleanArray.
*/
public void clear() {
mSize = 0;
}
/**
* Puts a key/value pair into the array, optimizing for the case where
* the key is greater than all existing keys in the array.
*/
public void append(int key, boolean value) {
if (mSize != 0 && key <= mKeys[mSize - 1]) {
put(key, value);
return;
}
mKeys = GrowingArrayUtils.append(mKeys, mSize, key);
mValues = GrowingArrayUtils.append(mValues, mSize, value);
mSize++;
}
@Override
public int hashCode() {
int hashCode = mSize;
for (int i = 0; i < mSize; i++) {
hashCode = 31 * hashCode + mKeys[i] | (mValues[i] ? 1 : 0);
}
return hashCode;
}
@Override
public boolean equals(@Nullable Object that) {
if (this == that) {
return true;
}
if (!(that instanceof SparseBooleanArray)) {
return false;
}
SparseBooleanArray other = (SparseBooleanArray) that;
if (mSize != other.mSize) {
return false;
}
for (int i = 0; i < mSize; i++) {
if (mKeys[i] != other.mKeys[i]) {
return false;
}
if (mValues[i] != other.mValues[i]) {
return false;
}
}
return true;
}
/**
* {@inheritDoc}
*
* This implementation composes a string by iterating over its mappings.
*/
@Override
public String toString() {
if (size() <= 0) {
return "{}";
}
StringBuilder buffer = new StringBuilder(mSize * 28);
buffer.append('{');
for (int i=0; i 0) {
buffer.append(", ");
}
int key = keyAt(i);
buffer.append(key);
buffer.append('=');
boolean value = valueAt(i);
buffer.append(value);
}
buffer.append('}');
return buffer.toString();
}
@UnsupportedAppUsage(maxTargetSdk = 28) // Use keyAt(int)
private int[] mKeys;
@UnsupportedAppUsage(maxTargetSdk = 28) // Use valueAt(int), setValueAt(int, boolean)
private boolean[] mValues;
@UnsupportedAppUsage(maxTargetSdk = 28) // Use size()
private int mSize;
}