| /* |
| * 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 com.android.internal.util.ArrayUtils; |
| import com.android.internal.util.GrowingArrayUtils; |
| |
| import libcore.util.EmptyArray; |
| |
| /** |
| * <code>SparseArray</code> maps integers to Objects and, unlike a normal array of Objects, |
| * its indices can contain gaps. <code>SparseArray</code> is intended to be more memory-efficient |
| * than a |
| * <a href="/reference/java/util/HashMap"><code>HashMap</code></a>, because it avoids |
| * auto-boxing keys and its data structure doesn't rely on an extra entry object |
| * for each mapping. |
| * |
| * <p>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 |
| * <code>HashMap</code> because 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 less than 50%. |
| * |
| * <p>To help with performance, the container includes an optimization when removing |
| * keys: instead of compacting its array immediately, it leaves the removed entry marked |
| * as deleted. The entry can then be re-used for the same key or compacted later in |
| * a single garbage collection of all removed entries. This garbage collection |
| * must be performed whenever the array needs to be grown, or when the map size or |
| * entry values are retrieved. |
| * |
| * <p>It is possible to iterate over the items in this container using |
| * {@link #keyAt(int)} and {@link #valueAt(int)}. Iterating over the keys using |
| * <code>keyAt(int)</code> with ascending values of the index returns the |
| * keys in ascending order. In the case of <code>valueAt(int)</code>, the |
| * values corresponding to the keys are returned in ascending order. |
| */ |
| public class SparseArray<E> implements Cloneable { |
| private static final Object DELETED = new Object(); |
| private boolean mGarbage = false; |
| |
| private int[] mKeys; |
| private Object[] mValues; |
| private int mSize; |
| |
| /** |
| * Creates a new SparseArray containing no mappings. |
| */ |
| public SparseArray() { |
| this(10); |
| } |
| |
| /** |
| * Creates a new SparseArray 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 SparseArray(int initialCapacity) { |
| if (initialCapacity == 0) { |
| mKeys = EmptyArray.INT; |
| mValues = EmptyArray.OBJECT; |
| } else { |
| mValues = ArrayUtils.newUnpaddedObjectArray(initialCapacity); |
| mKeys = new int[mValues.length]; |
| } |
| mSize = 0; |
| } |
| |
| @Override |
| @SuppressWarnings("unchecked") |
| public SparseArray<E> clone() { |
| SparseArray<E> clone = null; |
| try { |
| clone = (SparseArray<E>) super.clone(); |
| clone.mKeys = mKeys.clone(); |
| clone.mValues = mValues.clone(); |
| } catch (CloneNotSupportedException cnse) { |
| /* ignore */ |
| } |
| return clone; |
| } |
| |
| /** |
| * Gets the Object mapped from the specified key, or <code>null</code> |
| * if no such mapping has been made. |
| */ |
| public E get(int key) { |
| return get(key, null); |
| } |
| |
| /** |
| * Gets the Object mapped from the specified key, or the specified Object |
| * if no such mapping has been made. |
| */ |
| @SuppressWarnings("unchecked") |
| public E get(int key, E valueIfKeyNotFound) { |
| int i = ContainerHelpers.binarySearch(mKeys, mSize, key); |
| |
| if (i < 0 || mValues[i] == DELETED) { |
| return valueIfKeyNotFound; |
| } else { |
| return (E) 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) { |
| if (mValues[i] != DELETED) { |
| mValues[i] = DELETED; |
| mGarbage = true; |
| } |
| } |
| } |
| |
| /** |
| * @hide |
| * Removes the mapping from the specified key, if there was any, returning the old value. |
| */ |
| public E removeReturnOld(int key) { |
| int i = ContainerHelpers.binarySearch(mKeys, mSize, key); |
| |
| if (i >= 0) { |
| if (mValues[i] != DELETED) { |
| final E old = (E) mValues[i]; |
| mValues[i] = DELETED; |
| mGarbage = true; |
| return old; |
| } |
| } |
| return null; |
| } |
| |
| /** |
| * Alias for {@link #delete(int)}. |
| */ |
| public void remove(int key) { |
| delete(key); |
| } |
| |
| /** |
| * Removes the mapping at the specified index. |
| * |
| * <p>For indices outside of the range <code>0...size()-1</code>, |
| * the behavior is undefined.</p> |
| */ |
| public void removeAt(int index) { |
| if (mValues[index] != DELETED) { |
| mValues[index] = DELETED; |
| mGarbage = true; |
| } |
| } |
| |
| /** |
| * Remove a range of mappings as a batch. |
| * |
| * @param index Index to begin at |
| * @param size Number of mappings to remove |
| * |
| * <p>For indices outside of the range <code>0...size()-1</code>, |
| * the behavior is undefined.</p> |
| */ |
| public void removeAtRange(int index, int size) { |
| final int end = Math.min(mSize, index + size); |
| for (int i = index; i < end; i++) { |
| removeAt(i); |
| } |
| } |
| |
| private void gc() { |
| // Log.e("SparseArray", "gc start with " + mSize); |
| |
| int n = mSize; |
| int o = 0; |
| int[] keys = mKeys; |
| Object[] values = mValues; |
| |
| for (int i = 0; i < n; i++) { |
| Object val = values[i]; |
| |
| if (val != DELETED) { |
| if (i != o) { |
| keys[o] = keys[i]; |
| values[o] = val; |
| values[i] = null; |
| } |
| |
| o++; |
| } |
| } |
| |
| mGarbage = false; |
| mSize = o; |
| |
| // Log.e("SparseArray", "gc end with " + 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, E value) { |
| int i = ContainerHelpers.binarySearch(mKeys, mSize, key); |
| |
| if (i >= 0) { |
| mValues[i] = value; |
| } else { |
| i = ~i; |
| |
| if (i < mSize && mValues[i] == DELETED) { |
| mKeys[i] = key; |
| mValues[i] = value; |
| return; |
| } |
| |
| if (mGarbage && mSize >= mKeys.length) { |
| gc(); |
| |
| // Search again because indices may have changed. |
| i = ~ContainerHelpers.binarySearch(mKeys, mSize, key); |
| } |
| |
| mKeys = GrowingArrayUtils.insert(mKeys, mSize, i, key); |
| mValues = GrowingArrayUtils.insert(mValues, mSize, i, value); |
| mSize++; |
| } |
| } |
| |
| /** |
| * Returns the number of key-value mappings that this SparseArray |
| * currently stores. |
| */ |
| public int size() { |
| if (mGarbage) { |
| gc(); |
| } |
| |
| return mSize; |
| } |
| |
| /** |
| * Given an index in the range <code>0...size()-1</code>, returns |
| * the key from the <code>index</code>th key-value mapping that this |
| * SparseArray stores. |
| * |
| * <p>The keys corresponding to indices in ascending order are guaranteed to |
| * be in ascending order, e.g., <code>keyAt(0)</code> will return the |
| * smallest key and <code>keyAt(size()-1)</code> will return the largest |
| * key.</p> |
| * |
| * <p>For indices outside of the range <code>0...size()-1</code>, |
| * the behavior is undefined.</p> |
| */ |
| public int keyAt(int index) { |
| if (mGarbage) { |
| gc(); |
| } |
| |
| return mKeys[index]; |
| } |
| |
| /** |
| * Given an index in the range <code>0...size()-1</code>, returns |
| * the value from the <code>index</code>th key-value mapping that this |
| * SparseArray stores. |
| * |
| * <p>The values corresponding to indices in ascending order are guaranteed |
| * to be associated with keys in ascending order, e.g., |
| * <code>valueAt(0)</code> will return the value associated with the |
| * smallest key and <code>valueAt(size()-1)</code> will return the value |
| * associated with the largest key.</p> |
| * |
| * <p>For indices outside of the range <code>0...size()-1</code>, |
| * the behavior is undefined.</p> |
| */ |
| @SuppressWarnings("unchecked") |
| public E valueAt(int index) { |
| if (mGarbage) { |
| gc(); |
| } |
| |
| return (E) mValues[index]; |
| } |
| |
| /** |
| * Given an index in the range <code>0...size()-1</code>, sets a new |
| * value for the <code>index</code>th key-value mapping that this |
| * SparseArray stores. |
| * |
| * <p>For indices outside of the range <code>0...size()-1</code>, the behavior is undefined.</p> |
| */ |
| public void setValueAt(int index, E value) { |
| if (mGarbage) { |
| gc(); |
| } |
| |
| mValues[index] = value; |
| } |
| |
| /** |
| * 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) { |
| if (mGarbage) { |
| gc(); |
| } |
| |
| return ContainerHelpers.binarySearch(mKeys, mSize, key); |
| } |
| |
| /** |
| * Returns an index for which {@link #valueAt} would return the |
| * specified value, or a negative number if no keys map to the |
| * specified value. |
| * <p>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. |
| * <p>Note also that unlike most collections' {@code indexOf} methods, |
| * this method compares values using {@code ==} rather than {@code equals}. |
| */ |
| public int indexOfValue(E value) { |
| if (mGarbage) { |
| gc(); |
| } |
| |
| for (int i = 0; i < mSize; i++) { |
| if (mValues[i] == value) { |
| return i; |
| } |
| } |
| |
| return -1; |
| } |
| |
| /** |
| * Returns an index for which {@link #valueAt} would return the |
| * specified value, or a negative number if no keys map to the |
| * specified value. |
| * <p>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. |
| * <p>Note also that this method uses {@code equals} unlike {@code indexOfValue}. |
| * @hide |
| */ |
| public int indexOfValueByValue(E value) { |
| if (mGarbage) { |
| gc(); |
| } |
| |
| for (int i = 0; i < mSize; i++) { |
| if (value == null) { |
| if (mValues[i] == null) { |
| return i; |
| } |
| } else { |
| if (value.equals(mValues[i])) { |
| return i; |
| } |
| } |
| } |
| return -1; |
| } |
| |
| /** |
| * Removes all key-value mappings from this SparseArray. |
| */ |
| public void clear() { |
| int n = mSize; |
| Object[] values = mValues; |
| |
| for (int i = 0; i < n; i++) { |
| values[i] = null; |
| } |
| |
| mSize = 0; |
| mGarbage = false; |
| } |
| |
| /** |
| * 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, E value) { |
| if (mSize != 0 && key <= mKeys[mSize - 1]) { |
| put(key, value); |
| return; |
| } |
| |
| if (mGarbage && mSize >= mKeys.length) { |
| gc(); |
| } |
| |
| mKeys = GrowingArrayUtils.append(mKeys, mSize, key); |
| mValues = GrowingArrayUtils.append(mValues, mSize, value); |
| mSize++; |
| } |
| |
| /** |
| * {@inheritDoc} |
| * |
| * <p>This implementation composes a string by iterating over its mappings. If |
| * this map contains itself as a value, the string "(this Map)" |
| * will appear in its place. |
| */ |
| @Override |
| public String toString() { |
| if (size() <= 0) { |
| return "{}"; |
| } |
| |
| StringBuilder buffer = new StringBuilder(mSize * 28); |
| buffer.append('{'); |
| for (int i=0; i<mSize; i++) { |
| if (i > 0) { |
| buffer.append(", "); |
| } |
| int key = keyAt(i); |
| buffer.append(key); |
| buffer.append('='); |
| Object value = valueAt(i); |
| if (value != this) { |
| buffer.append(value); |
| } else { |
| buffer.append("(this Map)"); |
| } |
| } |
| buffer.append('}'); |
| return buffer.toString(); |
| } |
| } |