| /* |
| * Copyright (C) 2011 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.layoutlib.bridge.util; |
| |
| |
| import com.android.internal.util.ArrayUtils; |
| import com.android.internal.util.GrowingArrayUtils; |
| |
| import android.util.SparseArray; |
| |
| import java.lang.ref.WeakReference; |
| |
| /** |
| * This is a custom {@link SparseArray} that uses {@link WeakReference} around the objects added |
| * to it. When the array is compacted, not only deleted indices but also empty references |
| * are removed, making the array efficient at removing references that were reclaimed. |
| * |
| * The code is taken from {@link SparseArray} directly and adapted to use weak references. |
| * |
| * Because our usage means that we never actually call {@link #remove(long)} or |
| * {@link #delete(long)}, we must manually check if there are reclaimed references to |
| * trigger an internal compact step (which is normally only triggered when an item is manually |
| * removed). |
| * |
| * SparseArrays map integral values to Objects. Unlike a normal array of Objects, |
| * there can be gaps in the indices. It is intended to be more efficient |
| * than using a HashMap to map Integers (or Longs) to Objects. |
| */ |
| @SuppressWarnings("unchecked") |
| public class SparseWeakArray<E> { |
| |
| private static final Object DELETED_REF = new Object(); |
| private static final WeakReference<?> DELETED = new WeakReference(DELETED_REF); |
| private boolean mGarbage = false; |
| |
| /** |
| * Creates a new SparseArray containing no mappings. |
| */ |
| public SparseWeakArray() { |
| this(10); |
| } |
| |
| /** |
| * Creates a new SparseArray containing no mappings that will not |
| * require any additional memory allocation to store the specified |
| * number of mappings. |
| */ |
| public SparseWeakArray(int initialCapacity) { |
| mKeys = ArrayUtils.newUnpaddedLongArray(initialCapacity); |
| mValues = new WeakReference[mKeys.length]; |
| mSize = 0; |
| } |
| |
| /** |
| * Gets the Object mapped from the specified key, or <code>null</code> |
| * if no such mapping has been made. |
| */ |
| public E get(long key) { |
| return get(key, null); |
| } |
| |
| /** |
| * Gets the Object mapped from the specified key, or the specified Object |
| * if no such mapping has been made. |
| */ |
| public E get(long key, E valueIfKeyNotFound) { |
| int i = binarySearch(mKeys, 0, mSize, key); |
| |
| if (i < 0 || mValues[i] == DELETED || mValues[i].get() == null) { |
| return valueIfKeyNotFound; |
| } else { |
| return (E) mValues[i].get(); |
| } |
| } |
| |
| /** |
| * Removes the mapping from the specified key, if there was any. |
| */ |
| public void delete(long key) { |
| int i = binarySearch(mKeys, 0, mSize, key); |
| |
| if (i >= 0) { |
| if (mValues[i] != DELETED) { |
| mValues[i] = DELETED; |
| mGarbage = true; |
| } |
| } |
| } |
| |
| /** |
| * Alias for {@link #delete(long)}. |
| */ |
| public void remove(long key) { |
| delete(key); |
| } |
| |
| /** |
| * Removes the mapping at the specified index. |
| */ |
| public void removeAt(int index) { |
| if (mValues[index] != DELETED) { |
| mValues[index] = DELETED; |
| mGarbage = true; |
| } |
| } |
| |
| private void gc() { |
| int n = mSize; |
| int o = 0; |
| long[] keys = mKeys; |
| WeakReference<?>[] values = mValues; |
| |
| for (int i = 0; i < n; i++) { |
| WeakReference<?> val = values[i]; |
| |
| // Don't keep any non DELETED values, but only the one that still have a valid |
| // reference. |
| if (val != DELETED && val.get() != null) { |
| if (i != o) { |
| keys[o] = keys[i]; |
| values[o] = val; |
| } |
| |
| o++; |
| } |
| } |
| |
| mGarbage = false; |
| mSize = o; |
| } |
| |
| /** |
| * 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(long key, E value) { |
| int i = binarySearch(mKeys, 0, mSize, key); |
| |
| if (i >= 0) { |
| mValues[i] = new WeakReference(value); |
| } else { |
| i = ~i; |
| |
| if (i < mSize && (mValues[i] == DELETED || mValues[i].get() == null)) { |
| mKeys[i] = key; |
| mValues[i] = new WeakReference(value); |
| return; |
| } |
| |
| if (mSize >= mKeys.length && (mGarbage || hasReclaimedRefs())) { |
| gc(); |
| |
| // Search again because indices may have changed. |
| i = ~binarySearch(mKeys, 0, mSize, key); |
| } |
| |
| mKeys = GrowingArrayUtils.insert(mKeys, mSize, i, key); |
| mValues = GrowingArrayUtils.insert(mValues, mSize, i, new WeakReference(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. |
| */ |
| public long 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. |
| */ |
| public E valueAt(int index) { |
| if (mGarbage) { |
| gc(); |
| } |
| |
| return (E) mValues[index].get(); |
| } |
| |
| /** |
| * 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. |
| */ |
| public void setValueAt(int index, E value) { |
| if (mGarbage) { |
| gc(); |
| } |
| |
| mValues[index] = new WeakReference(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(long key) { |
| if (mGarbage) { |
| gc(); |
| } |
| |
| return binarySearch(mKeys, 0, 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(E value) { |
| if (mGarbage) { |
| gc(); |
| } |
| |
| for (int i = 0; i < mSize; i++) |
| if (mValues[i].get() == value) |
| return i; |
| |
| return -1; |
| } |
| |
| /** |
| * Removes all key-value mappings from this SparseArray. |
| */ |
| public void clear() { |
| int n = mSize; |
| WeakReference<?>[] 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(long key, E value) { |
| if (mSize != 0 && key <= mKeys[mSize - 1]) { |
| put(key, value); |
| return; |
| } |
| |
| if (mSize >= mKeys.length && (mGarbage || hasReclaimedRefs())) { |
| gc(); |
| } |
| |
| mKeys = GrowingArrayUtils.append(mKeys, mSize, key); |
| mValues = GrowingArrayUtils.append(mValues, mSize, new WeakReference(value)); |
| mSize++; |
| } |
| |
| private boolean hasReclaimedRefs() { |
| for (int i = 0 ; i < mSize ; i++) { |
| if (mValues[i].get() == null) { // DELETED.get() never returns null. |
| return true; |
| } |
| } |
| |
| return false; |
| } |
| |
| private static int binarySearch(long[] a, int start, int len, long key) { |
| int high = start + len, low = start - 1, guess; |
| |
| while (high - low > 1) { |
| guess = (high + low) / 2; |
| |
| if (a[guess] < key) |
| low = guess; |
| else |
| high = guess; |
| } |
| |
| if (high == start + len) |
| return ~(start + len); |
| else if (a[high] == key) |
| return high; |
| else |
| return ~high; |
| } |
| |
| private long[] mKeys; |
| private WeakReference<?>[] mValues; |
| private int mSize; |
| } |