/* * Copyright (C) 2009 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.support.v4.util; /** * SparseArray mapping longs 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 Longs to Objects. */ public class LongSparseArray implements Cloneable { private static final Object DELETED = new Object(); private boolean mGarbage = false; private long[] mKeys; private Object[] mValues; private int mSize; /** * Creates a new LongSparseArray containing no mappings. */ public LongSparseArray() { this(10); } /** * Creates a new LongSparseArray containing no mappings that will not * require any additional memory allocation to store the specified * number of mappings. */ public LongSparseArray(int initialCapacity) { initialCapacity = idealLongArraySize(initialCapacity); mKeys = new long[initialCapacity]; mValues = new Object[initialCapacity]; mSize = 0; } @Override @SuppressWarnings("unchecked") public LongSparseArray clone() { LongSparseArray clone = null; try { clone = (LongSparseArray) 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 null * 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. */ @SuppressWarnings("unchecked") public E get(long key, E valueIfKeyNotFound) { int i = binarySearch(mKeys, 0, 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(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() { // Log.e("SparseArray", "gc start with " + mSize); int n = mSize; int o = 0; long[] 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(long key, E value) { int i = binarySearch(mKeys, 0, 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 = ~binarySearch(mKeys, 0, mSize, key); } if (mSize >= mKeys.length) { int n = idealLongArraySize(mSize + 1); long[] nkeys = new long[n]; Object[] nvalues = new Object[n]; // Log.e("SparseArray", "grow " + mKeys.length + " to " + n); System.arraycopy(mKeys, 0, nkeys, 0, mKeys.length); System.arraycopy(mValues, 0, nvalues, 0, mValues.length); mKeys = nkeys; mValues = nvalues; } if (mSize - i != 0) { // Log.e("SparseArray", "move " + (mSize - i)); System.arraycopy(mKeys, i, mKeys, i + 1, mSize - i); System.arraycopy(mValues, i, mValues, i + 1, mSize - i); } mKeys[i] = key; mValues[i] = value; mSize++; } } /** * Returns the number of key-value mappings that this LongSparseArray * currently stores. */ public int size() { if (mGarbage) { gc(); } return mSize; } /** * Given an index in the range 0...size()-1, returns * the key from the indexth key-value mapping that this * LongSparseArray stores. */ public long keyAt(int index) { if (mGarbage) { gc(); } return mKeys[index]; } /** * Given an index in the range 0...size()-1, returns * the value from the indexth key-value mapping that this * LongSparseArray stores. */ @SuppressWarnings("unchecked") public E valueAt(int index) { if (mGarbage) { gc(); } return (E) mValues[index]; } /** * Given an index in the range 0...size()-1, sets a new * value for the indexth key-value mapping that this * LongSparseArray stores. */ 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(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] == value) return i; return -1; } /** * Removes all key-value mappings from this LongSparseArray. */ 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(long key, E value) { if (mSize != 0 && key <= mKeys[mSize - 1]) { put(key, value); return; } if (mGarbage && mSize >= mKeys.length) { gc(); } int pos = mSize; if (pos >= mKeys.length) { int n = idealLongArraySize(pos + 1); long[] nkeys = new long[n]; Object[] nvalues = new Object[n]; // Log.e("SparseArray", "grow " + mKeys.length + " to " + n); System.arraycopy(mKeys, 0, nkeys, 0, mKeys.length); System.arraycopy(mValues, 0, nvalues, 0, mValues.length); mKeys = nkeys; mValues = nvalues; } mKeys[pos] = key; mValues[pos] = value; mSize = pos + 1; } 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; } public static int idealByteArraySize(int need) { for (int i = 4; i < 32; i++) if (need <= (1 << i) - 12) return (1 << i) - 12; return need; } public static int idealLongArraySize(int need) { return idealByteArraySize(need * 8) / 8; } }