The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2006 The Android Open Source Project |
| 3 | * |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
| 7 | * |
| 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | * |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
| 16 | |
| 17 | package android.util; |
| 18 | |
| 19 | import com.android.internal.util.ArrayUtils; |
| 20 | |
| 21 | /** |
| 22 | * SparseArrays map integers to Objects. Unlike a normal array of Objects, |
Dianne Hackborn | b993f41 | 2013-07-12 17:46:45 -0700 | [diff] [blame^] | 23 | * there can be gaps in the indices. It is intended to be more memory efficient |
| 24 | * than using a HashMap to map Integers to Objects, both because it avoids |
| 25 | * auto-boxing keys and its data structure doesn't rely on an extra entry object |
| 26 | * for each mapping. |
| 27 | * |
| 28 | * <p>Note that this container keeps its mappings in an array data structure, |
| 29 | * using a binary search to find keys. The implementation is not intended to be appropriate for |
| 30 | * data structures |
| 31 | * that may contain large numbers of items. It is generally slower than a traditional |
| 32 | * HashMap, since lookups require a binary search and adds and removes require inserting |
| 33 | * and deleting entries in the array. For containers holding up to hundreds of items, |
| 34 | * the performance difference is not significant, less than 50%.</p> |
| 35 | * |
| 36 | * <p>To help with performance, the container includes an optimization when removing |
| 37 | * keys: instead of compacting its array immediately, it leaves the removed entry marked |
| 38 | * as deleted. The entry can then be re-used for the same key, or compacted later in |
| 39 | * a single garbage collection step of all removed entries. This garbage collection will |
| 40 | * need to be performed at any time the array needs to be grown or the the map size or |
| 41 | * entry values are retrieved.</p> |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 42 | */ |
Svetoslav Ganov | 35bfede | 2011-07-14 17:57:06 -0700 | [diff] [blame] | 43 | public class SparseArray<E> implements Cloneable { |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 44 | private static final Object DELETED = new Object(); |
Dianne Hackborn | f4bf0ae | 2013-05-20 18:42:16 -0700 | [diff] [blame] | 45 | static final int[] EMPTY_INTS = new int[0]; |
| 46 | static final Object[] EMPTY_OBJECTS = new Object[0]; |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 47 | private boolean mGarbage = false; |
| 48 | |
Svetoslav Ganov | 35bfede | 2011-07-14 17:57:06 -0700 | [diff] [blame] | 49 | private int[] mKeys; |
| 50 | private Object[] mValues; |
| 51 | private int mSize; |
| 52 | |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 53 | /** |
| 54 | * Creates a new SparseArray containing no mappings. |
| 55 | */ |
| 56 | public SparseArray() { |
| 57 | this(10); |
| 58 | } |
| 59 | |
| 60 | /** |
| 61 | * Creates a new SparseArray containing no mappings that will not |
| 62 | * require any additional memory allocation to store the specified |
Dianne Hackborn | f4bf0ae | 2013-05-20 18:42:16 -0700 | [diff] [blame] | 63 | * number of mappings. If you supply an initial capacity of 0, the |
| 64 | * sparse array will be initialized with a light-weight representation |
| 65 | * not requiring any additional array allocations. |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 66 | */ |
| 67 | public SparseArray(int initialCapacity) { |
Dianne Hackborn | f4bf0ae | 2013-05-20 18:42:16 -0700 | [diff] [blame] | 68 | if (initialCapacity == 0) { |
| 69 | mKeys = EMPTY_INTS; |
| 70 | mValues = EMPTY_OBJECTS; |
| 71 | } else { |
| 72 | initialCapacity = ArrayUtils.idealIntArraySize(initialCapacity); |
| 73 | mKeys = new int[initialCapacity]; |
| 74 | mValues = new Object[initialCapacity]; |
| 75 | } |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 76 | mSize = 0; |
| 77 | } |
| 78 | |
Svetoslav Ganov | 35bfede | 2011-07-14 17:57:06 -0700 | [diff] [blame] | 79 | @Override |
| 80 | @SuppressWarnings("unchecked") |
| 81 | public SparseArray<E> clone() { |
| 82 | SparseArray<E> clone = null; |
| 83 | try { |
| 84 | clone = (SparseArray<E>) super.clone(); |
| 85 | clone.mKeys = mKeys.clone(); |
| 86 | clone.mValues = mValues.clone(); |
| 87 | } catch (CloneNotSupportedException cnse) { |
| 88 | /* ignore */ |
| 89 | } |
| 90 | return clone; |
| 91 | } |
| 92 | |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 93 | /** |
| 94 | * Gets the Object mapped from the specified key, or <code>null</code> |
| 95 | * if no such mapping has been made. |
| 96 | */ |
| 97 | public E get(int key) { |
| 98 | return get(key, null); |
| 99 | } |
| 100 | |
| 101 | /** |
| 102 | * Gets the Object mapped from the specified key, or the specified Object |
| 103 | * if no such mapping has been made. |
| 104 | */ |
Svetoslav Ganov | 35bfede | 2011-07-14 17:57:06 -0700 | [diff] [blame] | 105 | @SuppressWarnings("unchecked") |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 106 | public E get(int key, E valueIfKeyNotFound) { |
Dianne Hackborn | f4bf0ae | 2013-05-20 18:42:16 -0700 | [diff] [blame] | 107 | int i = binarySearch(mKeys, mSize, key); |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 108 | |
| 109 | if (i < 0 || mValues[i] == DELETED) { |
| 110 | return valueIfKeyNotFound; |
| 111 | } else { |
| 112 | return (E) mValues[i]; |
| 113 | } |
| 114 | } |
| 115 | |
| 116 | /** |
| 117 | * Removes the mapping from the specified key, if there was any. |
| 118 | */ |
| 119 | public void delete(int key) { |
Dianne Hackborn | f4bf0ae | 2013-05-20 18:42:16 -0700 | [diff] [blame] | 120 | int i = binarySearch(mKeys, mSize, key); |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 121 | |
| 122 | if (i >= 0) { |
| 123 | if (mValues[i] != DELETED) { |
| 124 | mValues[i] = DELETED; |
| 125 | mGarbage = true; |
| 126 | } |
| 127 | } |
| 128 | } |
| 129 | |
| 130 | /** |
| 131 | * Alias for {@link #delete(int)}. |
| 132 | */ |
| 133 | public void remove(int key) { |
| 134 | delete(key); |
| 135 | } |
| 136 | |
Dianne Hackborn | c801768 | 2010-07-06 13:34:38 -0700 | [diff] [blame] | 137 | /** |
| 138 | * Removes the mapping at the specified index. |
| 139 | */ |
| 140 | public void removeAt(int index) { |
| 141 | if (mValues[index] != DELETED) { |
| 142 | mValues[index] = DELETED; |
| 143 | mGarbage = true; |
| 144 | } |
| 145 | } |
Elliott Hughes | 58aff7d | 2013-03-26 16:34:30 -0700 | [diff] [blame] | 146 | |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 147 | private void gc() { |
| 148 | // Log.e("SparseArray", "gc start with " + mSize); |
| 149 | |
| 150 | int n = mSize; |
| 151 | int o = 0; |
| 152 | int[] keys = mKeys; |
| 153 | Object[] values = mValues; |
| 154 | |
| 155 | for (int i = 0; i < n; i++) { |
| 156 | Object val = values[i]; |
| 157 | |
| 158 | if (val != DELETED) { |
| 159 | if (i != o) { |
| 160 | keys[o] = keys[i]; |
| 161 | values[o] = val; |
Svetoslav Ganov | d116d7c | 2011-11-21 18:41:59 -0800 | [diff] [blame] | 162 | values[i] = null; |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 163 | } |
| 164 | |
| 165 | o++; |
| 166 | } |
| 167 | } |
| 168 | |
| 169 | mGarbage = false; |
| 170 | mSize = o; |
| 171 | |
| 172 | // Log.e("SparseArray", "gc end with " + mSize); |
| 173 | } |
| 174 | |
| 175 | /** |
| 176 | * Adds a mapping from the specified key to the specified value, |
| 177 | * replacing the previous mapping from the specified key if there |
| 178 | * was one. |
| 179 | */ |
| 180 | public void put(int key, E value) { |
Dianne Hackborn | f4bf0ae | 2013-05-20 18:42:16 -0700 | [diff] [blame] | 181 | int i = binarySearch(mKeys, mSize, key); |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 182 | |
| 183 | if (i >= 0) { |
| 184 | mValues[i] = value; |
| 185 | } else { |
| 186 | i = ~i; |
| 187 | |
| 188 | if (i < mSize && mValues[i] == DELETED) { |
| 189 | mKeys[i] = key; |
| 190 | mValues[i] = value; |
| 191 | return; |
| 192 | } |
| 193 | |
| 194 | if (mGarbage && mSize >= mKeys.length) { |
| 195 | gc(); |
| 196 | |
| 197 | // Search again because indices may have changed. |
Dianne Hackborn | f4bf0ae | 2013-05-20 18:42:16 -0700 | [diff] [blame] | 198 | i = ~binarySearch(mKeys, mSize, key); |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 199 | } |
| 200 | |
| 201 | if (mSize >= mKeys.length) { |
| 202 | int n = ArrayUtils.idealIntArraySize(mSize + 1); |
| 203 | |
| 204 | int[] nkeys = new int[n]; |
| 205 | Object[] nvalues = new Object[n]; |
| 206 | |
| 207 | // Log.e("SparseArray", "grow " + mKeys.length + " to " + n); |
| 208 | System.arraycopy(mKeys, 0, nkeys, 0, mKeys.length); |
| 209 | System.arraycopy(mValues, 0, nvalues, 0, mValues.length); |
| 210 | |
| 211 | mKeys = nkeys; |
| 212 | mValues = nvalues; |
| 213 | } |
| 214 | |
| 215 | if (mSize - i != 0) { |
| 216 | // Log.e("SparseArray", "move " + (mSize - i)); |
| 217 | System.arraycopy(mKeys, i, mKeys, i + 1, mSize - i); |
| 218 | System.arraycopy(mValues, i, mValues, i + 1, mSize - i); |
| 219 | } |
| 220 | |
| 221 | mKeys[i] = key; |
| 222 | mValues[i] = value; |
| 223 | mSize++; |
| 224 | } |
| 225 | } |
| 226 | |
| 227 | /** |
| 228 | * Returns the number of key-value mappings that this SparseArray |
| 229 | * currently stores. |
| 230 | */ |
| 231 | public int size() { |
| 232 | if (mGarbage) { |
| 233 | gc(); |
| 234 | } |
| 235 | |
| 236 | return mSize; |
| 237 | } |
| 238 | |
| 239 | /** |
| 240 | * Given an index in the range <code>0...size()-1</code>, returns |
| 241 | * the key from the <code>index</code>th key-value mapping that this |
Elliott Hughes | 58aff7d | 2013-03-26 16:34:30 -0700 | [diff] [blame] | 242 | * SparseArray stores. |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 243 | */ |
| 244 | public int keyAt(int index) { |
| 245 | if (mGarbage) { |
| 246 | gc(); |
| 247 | } |
| 248 | |
| 249 | return mKeys[index]; |
| 250 | } |
Elliott Hughes | 58aff7d | 2013-03-26 16:34:30 -0700 | [diff] [blame] | 251 | |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 252 | /** |
| 253 | * Given an index in the range <code>0...size()-1</code>, returns |
| 254 | * the value from the <code>index</code>th key-value mapping that this |
Elliott Hughes | 58aff7d | 2013-03-26 16:34:30 -0700 | [diff] [blame] | 255 | * SparseArray stores. |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 256 | */ |
Svetoslav Ganov | 35bfede | 2011-07-14 17:57:06 -0700 | [diff] [blame] | 257 | @SuppressWarnings("unchecked") |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 258 | public E valueAt(int index) { |
| 259 | if (mGarbage) { |
| 260 | gc(); |
| 261 | } |
| 262 | |
| 263 | return (E) mValues[index]; |
| 264 | } |
| 265 | |
| 266 | /** |
| 267 | * Given an index in the range <code>0...size()-1</code>, sets a new |
| 268 | * value for the <code>index</code>th key-value mapping that this |
Elliott Hughes | 58aff7d | 2013-03-26 16:34:30 -0700 | [diff] [blame] | 269 | * SparseArray stores. |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 270 | */ |
| 271 | public void setValueAt(int index, E value) { |
| 272 | if (mGarbage) { |
| 273 | gc(); |
| 274 | } |
| 275 | |
| 276 | mValues[index] = value; |
| 277 | } |
Elliott Hughes | 58aff7d | 2013-03-26 16:34:30 -0700 | [diff] [blame] | 278 | |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 279 | /** |
| 280 | * Returns the index for which {@link #keyAt} would return the |
| 281 | * specified key, or a negative number if the specified |
| 282 | * key is not mapped. |
| 283 | */ |
| 284 | public int indexOfKey(int key) { |
| 285 | if (mGarbage) { |
| 286 | gc(); |
| 287 | } |
| 288 | |
Dianne Hackborn | f4bf0ae | 2013-05-20 18:42:16 -0700 | [diff] [blame] | 289 | return binarySearch(mKeys, mSize, key); |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 290 | } |
| 291 | |
| 292 | /** |
| 293 | * Returns an index for which {@link #valueAt} would return the |
| 294 | * specified key, or a negative number if no keys map to the |
| 295 | * specified value. |
Elliott Hughes | 58aff7d | 2013-03-26 16:34:30 -0700 | [diff] [blame] | 296 | * <p>Beware that this is a linear search, unlike lookups by key, |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 297 | * and that multiple keys can map to the same value and this will |
| 298 | * find only one of them. |
Elliott Hughes | 58aff7d | 2013-03-26 16:34:30 -0700 | [diff] [blame] | 299 | * <p>Note also that unlike most collections' {@code indexOf} methods, |
| 300 | * this method compares values using {@code ==} rather than {@code equals}. |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 301 | */ |
| 302 | public int indexOfValue(E value) { |
| 303 | if (mGarbage) { |
| 304 | gc(); |
| 305 | } |
| 306 | |
| 307 | for (int i = 0; i < mSize; i++) |
| 308 | if (mValues[i] == value) |
| 309 | return i; |
| 310 | |
| 311 | return -1; |
| 312 | } |
| 313 | |
| 314 | /** |
| 315 | * Removes all key-value mappings from this SparseArray. |
| 316 | */ |
| 317 | public void clear() { |
| 318 | int n = mSize; |
| 319 | Object[] values = mValues; |
| 320 | |
| 321 | for (int i = 0; i < n; i++) { |
| 322 | values[i] = null; |
| 323 | } |
| 324 | |
| 325 | mSize = 0; |
| 326 | mGarbage = false; |
| 327 | } |
| 328 | |
| 329 | /** |
| 330 | * Puts a key/value pair into the array, optimizing for the case where |
| 331 | * the key is greater than all existing keys in the array. |
| 332 | */ |
| 333 | public void append(int key, E value) { |
| 334 | if (mSize != 0 && key <= mKeys[mSize - 1]) { |
| 335 | put(key, value); |
| 336 | return; |
| 337 | } |
| 338 | |
| 339 | if (mGarbage && mSize >= mKeys.length) { |
| 340 | gc(); |
| 341 | } |
| 342 | |
| 343 | int pos = mSize; |
| 344 | if (pos >= mKeys.length) { |
| 345 | int n = ArrayUtils.idealIntArraySize(pos + 1); |
| 346 | |
| 347 | int[] nkeys = new int[n]; |
| 348 | Object[] nvalues = new Object[n]; |
| 349 | |
| 350 | // Log.e("SparseArray", "grow " + mKeys.length + " to " + n); |
| 351 | System.arraycopy(mKeys, 0, nkeys, 0, mKeys.length); |
| 352 | System.arraycopy(mValues, 0, nvalues, 0, mValues.length); |
| 353 | |
| 354 | mKeys = nkeys; |
| 355 | mValues = nvalues; |
| 356 | } |
| 357 | |
| 358 | mKeys[pos] = key; |
| 359 | mValues[pos] = value; |
| 360 | mSize = pos + 1; |
| 361 | } |
Elliott Hughes | 58aff7d | 2013-03-26 16:34:30 -0700 | [diff] [blame] | 362 | |
Dianne Hackborn | f4bf0ae | 2013-05-20 18:42:16 -0700 | [diff] [blame] | 363 | // This is Arrays.binarySearch(), but doesn't do any argument validation. |
| 364 | static int binarySearch(int[] array, int size, int value) { |
| 365 | int lo = 0; |
| 366 | int hi = size - 1; |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 367 | |
Dianne Hackborn | f4bf0ae | 2013-05-20 18:42:16 -0700 | [diff] [blame] | 368 | while (lo <= hi) { |
| 369 | int mid = (lo + hi) >>> 1; |
| 370 | int midVal = array[mid]; |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 371 | |
Dianne Hackborn | f4bf0ae | 2013-05-20 18:42:16 -0700 | [diff] [blame] | 372 | if (midVal < value) { |
| 373 | lo = mid + 1; |
| 374 | } else if (midVal > value) { |
| 375 | hi = mid - 1; |
| 376 | } else { |
| 377 | return mid; // value found |
| 378 | } |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 379 | } |
Dianne Hackborn | f4bf0ae | 2013-05-20 18:42:16 -0700 | [diff] [blame] | 380 | return ~lo; // value not present |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 381 | } |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 382 | } |