1/* 2 * Copyright (C) 2013 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 18package android.support.v7.widget; 19 20import java.util.ArrayList; 21 22/** 23 * Like a SparseArray, but with the ability to offset key ranges for bulk insertions/deletions. 24 */ 25class PositionMap<E> implements Cloneable { 26 private static final Object DELETED = new Object(); 27 private boolean mGarbage = false; 28 29 private int[] mKeys; 30 private Object[] mValues; 31 private int mSize; 32 33 /** 34 * Creates a new SparseArray containing no mappings. 35 */ 36 public PositionMap() { 37 this(10); 38 } 39 40 /** 41 * Creates a new PositionMap containing no mappings that will not 42 * require any additional memory allocation to store the specified 43 * number of mappings. If you supply an initial capacity of 0, the 44 * sparse array will be initialized with a light-weight representation 45 * not requiring any additional array allocations. 46 */ 47 public PositionMap(int initialCapacity) { 48 if (initialCapacity == 0) { 49 mKeys = ContainerHelpers.EMPTY_INTS; 50 mValues = ContainerHelpers.EMPTY_OBJECTS; 51 } else { 52 initialCapacity = idealIntArraySize(initialCapacity); 53 mKeys = new int[initialCapacity]; 54 mValues = new Object[initialCapacity]; 55 } 56 mSize = 0; 57 } 58 59 @Override 60 @SuppressWarnings("unchecked") 61 public PositionMap<E> clone() { 62 PositionMap<E> clone = null; 63 try { 64 clone = (PositionMap<E>) super.clone(); 65 clone.mKeys = mKeys.clone(); 66 clone.mValues = mValues.clone(); 67 } catch (CloneNotSupportedException cnse) { 68 /* ignore */ 69 } 70 return clone; 71 } 72 73 /** 74 * Gets the Object mapped from the specified key, or <code>null</code> 75 * if no such mapping has been made. 76 */ 77 public E get(int key) { 78 return get(key, null); 79 } 80 81 /** 82 * Gets the Object mapped from the specified key, or the specified Object 83 * if no such mapping has been made. 84 */ 85 @SuppressWarnings("unchecked") 86 public E get(int key, E valueIfKeyNotFound) { 87 int i = ContainerHelpers.binarySearch(mKeys, mSize, key); 88 89 if (i < 0 || mValues[i] == DELETED) { 90 return valueIfKeyNotFound; 91 } else { 92 return (E) mValues[i]; 93 } 94 } 95 96 /** 97 * Removes the mapping from the specified key, if there was any. 98 */ 99 public void delete(int key) { 100 int i = ContainerHelpers.binarySearch(mKeys, mSize, key); 101 102 if (i >= 0) { 103 if (mValues[i] != DELETED) { 104 mValues[i] = DELETED; 105 mGarbage = true; 106 } 107 } 108 } 109 110 /** 111 * Alias for {@link #delete(int)}. 112 */ 113 public void remove(int key) { 114 delete(key); 115 } 116 117 /** 118 * Removes the mapping at the specified index. 119 */ 120 public void removeAt(int index) { 121 if (mValues[index] != DELETED) { 122 mValues[index] = DELETED; 123 mGarbage = true; 124 } 125 } 126 127 /** 128 * Remove a range of mappings as a batch. 129 * 130 * @param index Index to begin at 131 * @param size Number of mappings to remove 132 */ 133 public void removeAtRange(int index, int size) { 134 final int end = Math.min(mSize, index + size); 135 for (int i = index; i < end; i++) { 136 removeAt(i); 137 } 138 } 139 140 public void insertKeyRange(int keyStart, int count) { 141 142 } 143 144 public void removeKeyRange(ArrayList<E> removedItems, int keyStart, int count) { 145 146 } 147 148 private void gc() { 149 // Log.e("SparseArray", "gc start with " + mSize); 150 151 int n = mSize; 152 int o = 0; 153 int[] keys = mKeys; 154 Object[] values = mValues; 155 156 for (int i = 0; i < n; i++) { 157 Object val = values[i]; 158 159 if (val != DELETED) { 160 if (i != o) { 161 keys[o] = keys[i]; 162 values[o] = val; 163 values[i] = null; 164 } 165 166 o++; 167 } 168 } 169 170 mGarbage = false; 171 mSize = o; 172 173 // Log.e("SparseArray", "gc end with " + mSize); 174 } 175 176 /** 177 * Adds a mapping from the specified key to the specified value, 178 * replacing the previous mapping from the specified key if there 179 * was one. 180 */ 181 public void put(int key, E value) { 182 int i = ContainerHelpers.binarySearch(mKeys, mSize, key); 183 184 if (i >= 0) { 185 mValues[i] = value; 186 } else { 187 i = ~i; 188 189 if (i < mSize && mValues[i] == DELETED) { 190 mKeys[i] = key; 191 mValues[i] = value; 192 return; 193 } 194 195 if (mGarbage && mSize >= mKeys.length) { 196 gc(); 197 198 // Search again because indices may have changed. 199 i = ~ContainerHelpers.binarySearch(mKeys, mSize, key); 200 } 201 202 if (mSize >= mKeys.length) { 203 int n = idealIntArraySize(mSize + 1); 204 205 int[] nkeys = new int[n]; 206 Object[] nvalues = new Object[n]; 207 208 // Log.e("SparseArray", "grow " + mKeys.length + " to " + n); 209 System.arraycopy(mKeys, 0, nkeys, 0, mKeys.length); 210 System.arraycopy(mValues, 0, nvalues, 0, mValues.length); 211 212 mKeys = nkeys; 213 mValues = nvalues; 214 } 215 216 if (mSize - i != 0) { 217 // Log.e("SparseArray", "move " + (mSize - i)); 218 System.arraycopy(mKeys, i, mKeys, i + 1, mSize - i); 219 System.arraycopy(mValues, i, mValues, i + 1, mSize - i); 220 } 221 222 mKeys[i] = key; 223 mValues[i] = value; 224 mSize++; 225 } 226 } 227 228 /** 229 * Returns the number of key-value mappings that this SparseArray 230 * currently stores. 231 */ 232 public int size() { 233 if (mGarbage) { 234 gc(); 235 } 236 237 return mSize; 238 } 239 240 /** 241 * Given an index in the range <code>0...size()-1</code>, returns 242 * the key from the <code>index</code>th key-value mapping that this 243 * SparseArray stores. 244 */ 245 public int keyAt(int index) { 246 if (mGarbage) { 247 gc(); 248 } 249 250 return mKeys[index]; 251 } 252 253 /** 254 * Given an index in the range <code>0...size()-1</code>, returns 255 * the value from the <code>index</code>th key-value mapping that this 256 * SparseArray stores. 257 */ 258 @SuppressWarnings("unchecked") 259 public E valueAt(int index) { 260 if (mGarbage) { 261 gc(); 262 } 263 264 return (E) mValues[index]; 265 } 266 267 /** 268 * Given an index in the range <code>0...size()-1</code>, sets a new 269 * value for the <code>index</code>th key-value mapping that this 270 * SparseArray stores. 271 */ 272 public void setValueAt(int index, E value) { 273 if (mGarbage) { 274 gc(); 275 } 276 277 mValues[index] = value; 278 } 279 280 /** 281 * Returns the index for which {@link #keyAt} would return the 282 * specified key, or a negative number if the specified 283 * key is not mapped. 284 */ 285 public int indexOfKey(int key) { 286 if (mGarbage) { 287 gc(); 288 } 289 290 return ContainerHelpers.binarySearch(mKeys, mSize, key); 291 } 292 293 /** 294 * Returns an index for which {@link #valueAt} would return the 295 * specified key, or a negative number if no keys map to the 296 * specified value. 297 * <p>Beware that this is a linear search, unlike lookups by key, 298 * and that multiple keys can map to the same value and this will 299 * find only one of them. 300 * <p>Note also that unlike most collections' {@code indexOf} methods, 301 * this method compares values using {@code ==} rather than {@code equals}. 302 */ 303 public int indexOfValue(E value) { 304 if (mGarbage) { 305 gc(); 306 } 307 308 for (int i = 0; i < mSize; i++) 309 if (mValues[i] == value) 310 return i; 311 312 return -1; 313 } 314 315 /** 316 * Removes all key-value mappings from this SparseArray. 317 */ 318 public void clear() { 319 int n = mSize; 320 Object[] values = mValues; 321 322 for (int i = 0; i < n; i++) { 323 values[i] = null; 324 } 325 326 mSize = 0; 327 mGarbage = false; 328 } 329 330 /** 331 * Puts a key/value pair into the array, optimizing for the case where 332 * the key is greater than all existing keys in the array. 333 */ 334 public void append(int key, E value) { 335 if (mSize != 0 && key <= mKeys[mSize - 1]) { 336 put(key, value); 337 return; 338 } 339 340 if (mGarbage && mSize >= mKeys.length) { 341 gc(); 342 } 343 344 int pos = mSize; 345 if (pos >= mKeys.length) { 346 int n = idealIntArraySize(pos + 1); 347 348 int[] nkeys = new int[n]; 349 Object[] nvalues = new Object[n]; 350 351 // Log.e("SparseArray", "grow " + mKeys.length + " to " + n); 352 System.arraycopy(mKeys, 0, nkeys, 0, mKeys.length); 353 System.arraycopy(mValues, 0, nvalues, 0, mValues.length); 354 355 mKeys = nkeys; 356 mValues = nvalues; 357 } 358 359 mKeys[pos] = key; 360 mValues[pos] = value; 361 mSize = pos + 1; 362 } 363 364 /** 365 * {@inheritDoc} 366 * 367 * <p>This implementation composes a string by iterating over its mappings. If 368 * this map contains itself as a value, the string "(this Map)" 369 * will appear in its place. 370 */ 371 @Override 372 public String toString() { 373 if (size() <= 0) { 374 return "{}"; 375 } 376 377 StringBuilder buffer = new StringBuilder(mSize * 28); 378 buffer.append('{'); 379 for (int i=0; i<mSize; i++) { 380 if (i > 0) { 381 buffer.append(", "); 382 } 383 int key = keyAt(i); 384 buffer.append(key); 385 buffer.append('='); 386 Object value = valueAt(i); 387 if (value != this) { 388 buffer.append(value); 389 } else { 390 buffer.append("(this Map)"); 391 } 392 } 393 buffer.append('}'); 394 return buffer.toString(); 395 } 396 397 static int idealByteArraySize(int need) { 398 for (int i = 4; i < 32; i++) 399 if (need <= (1 << i) - 12) 400 return (1 << i) - 12; 401 402 return need; 403 } 404 405 static int idealBooleanArraySize(int need) { 406 return idealByteArraySize(need); 407 } 408 409 static int idealShortArraySize(int need) { 410 return idealByteArraySize(need * 2) / 2; 411 } 412 413 static int idealCharArraySize(int need) { 414 return idealByteArraySize(need * 2) / 2; 415 } 416 417 static int idealIntArraySize(int need) { 418 return idealByteArraySize(need * 4) / 4; 419 } 420 421 static int idealFloatArraySize(int need) { 422 return idealByteArraySize(need * 4) / 4; 423 } 424 425 static int idealObjectArraySize(int need) { 426 return idealByteArraySize(need * 4) / 4; 427 } 428 429 static int idealLongArraySize(int need) { 430 return idealByteArraySize(need * 8) / 8; 431 } 432 433 static class ContainerHelpers { 434 static final boolean[] EMPTY_BOOLEANS = new boolean[0]; 435 static final int[] EMPTY_INTS = new int[0]; 436 static final long[] EMPTY_LONGS = new long[0]; 437 static final Object[] EMPTY_OBJECTS = new Object[0]; 438 439 // This is Arrays.binarySearch(), but doesn't do any argument validation. 440 static int binarySearch(int[] array, int size, int value) { 441 int lo = 0; 442 int hi = size - 1; 443 444 while (lo <= hi) { 445 final int mid = (lo + hi) >>> 1; 446 final int midVal = array[mid]; 447 448 if (midVal < value) { 449 lo = mid + 1; 450 } else if (midVal > value) { 451 hi = mid - 1; 452 } else { 453 return mid; // value found 454 } 455 } 456 return ~lo; // value not present 457 } 458 } 459 460} 461