Raymond | dee0849 | 2015-04-02 10:43:13 -0700 | [diff] [blame] | 1 | /* |
| 2 | * Licensed to the Apache Software Foundation (ASF) under one or more |
| 3 | * contributor license agreements. See the NOTICE file distributed with |
| 4 | * this work for additional information regarding copyright ownership. |
| 5 | * The ASF licenses this file to You under the Apache License, Version 2.0 |
| 6 | * (the "License"); you may not use this file except in compliance with |
| 7 | * the License. You may obtain a copy of the License at |
| 8 | * |
| 9 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 10 | * |
| 11 | * Unless required by applicable law or agreed to in writing, software |
| 12 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 13 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 14 | * See the License for the specific language governing permissions and |
| 15 | * limitations under the License. |
| 16 | */ |
| 17 | package org.apache.commons.math.util; |
| 18 | |
| 19 | import java.io.Serializable; |
| 20 | import java.util.Arrays; |
| 21 | |
| 22 | import org.apache.commons.math.MathRuntimeException; |
| 23 | import org.apache.commons.math.exception.util.LocalizedFormats; |
| 24 | |
| 25 | /** |
| 26 | * <p> |
| 27 | * A variable length {@link DoubleArray} implementation that automatically |
| 28 | * handles expanding and contracting its internal storage array as elements |
| 29 | * are added and removed. |
| 30 | * </p> |
| 31 | * <p> |
| 32 | * The internal storage array starts with capacity determined by the |
| 33 | * <code>initialCapacity</code> property, which can be set by the constructor. |
| 34 | * The default initial capacity is 16. Adding elements using |
| 35 | * {@link #addElement(double)} appends elements to the end of the array. When |
| 36 | * there are no open entries at the end of the internal storage array, the |
| 37 | * array is expanded. The size of the expanded array depends on the |
| 38 | * <code>expansionMode</code> and <code>expansionFactor</code> properties. |
| 39 | * The <code>expansionMode</code> determines whether the size of the array is |
| 40 | * multiplied by the <code>expansionFactor</code> (MULTIPLICATIVE_MODE) or if |
| 41 | * the expansion is additive (ADDITIVE_MODE -- <code>expansionFactor</code> |
| 42 | * storage locations added). The default <code>expansionMode</code> is |
| 43 | * MULTIPLICATIVE_MODE and the default <code>expansionFactor</code> |
| 44 | * is 2.0. |
| 45 | * </p> |
| 46 | * <p> |
| 47 | * The {@link #addElementRolling(double)} method adds a new element to the end |
| 48 | * of the internal storage array and adjusts the "usable window" of the |
| 49 | * internal array forward by one position (effectively making what was the |
| 50 | * second element the first, and so on). Repeated activations of this method |
| 51 | * (or activation of {@link #discardFrontElements(int)}) will effectively orphan |
| 52 | * the storage locations at the beginning of the internal storage array. To |
| 53 | * reclaim this storage, each time one of these methods is activated, the size |
| 54 | * of the internal storage array is compared to the number of addressable |
| 55 | * elements (the <code>numElements</code> property) and if the difference |
| 56 | * is too large, the internal array is contracted to size |
| 57 | * <code>numElements + 1.</code> The determination of when the internal |
| 58 | * storage array is "too large" depends on the <code>expansionMode</code> and |
| 59 | * <code>contractionFactor</code> properties. If the <code>expansionMode</code> |
| 60 | * is <code>MULTIPLICATIVE_MODE</code>, contraction is triggered when the |
| 61 | * ratio between storage array length and <code>numElements</code> exceeds |
| 62 | * <code>contractionFactor.</code> If the <code>expansionMode</code> |
| 63 | * is <code>ADDITIVE_MODE,</code> the number of excess storage locations |
| 64 | * is compared to <code>contractionFactor.</code> |
| 65 | * </p> |
| 66 | * <p> |
| 67 | * To avoid cycles of expansions and contractions, the |
| 68 | * <code>expansionFactor</code> must not exceed the |
| 69 | * <code>contractionFactor.</code> Constructors and mutators for both of these |
| 70 | * properties enforce this requirement, throwing IllegalArgumentException if it |
| 71 | * is violated. |
| 72 | * </p> |
| 73 | * @version $Revision: 1073474 $ $Date: 2011-02-22 20:52:17 +0100 (mar. 22 févr. 2011) $ |
| 74 | */ |
| 75 | public class ResizableDoubleArray implements DoubleArray, Serializable { |
| 76 | |
| 77 | /** additive expansion mode */ |
| 78 | public static final int ADDITIVE_MODE = 1; |
| 79 | |
| 80 | /** multiplicative expansion mode */ |
| 81 | public static final int MULTIPLICATIVE_MODE = 0; |
| 82 | |
| 83 | /** Serializable version identifier */ |
| 84 | private static final long serialVersionUID = -3485529955529426875L; |
| 85 | |
| 86 | /** |
| 87 | * The contraction criteria determines when the internal array will be |
| 88 | * contracted to fit the number of elements contained in the element |
| 89 | * array + 1. |
| 90 | */ |
| 91 | protected float contractionCriteria = 2.5f; |
| 92 | |
| 93 | /** |
| 94 | * The expansion factor of the array. When the array needs to be expanded, |
| 95 | * the new array size will be |
| 96 | * <code>internalArray.length * expansionFactor</code> |
| 97 | * if <code>expansionMode</code> is set to MULTIPLICATIVE_MODE, or |
| 98 | * <code>internalArray.length + expansionFactor</code> if |
| 99 | * <code>expansionMode</code> is set to ADDITIVE_MODE. |
| 100 | */ |
| 101 | protected float expansionFactor = 2.0f; |
| 102 | |
| 103 | /** |
| 104 | * Determines whether array expansion by <code>expansionFactor</code> |
| 105 | * is additive or multiplicative. |
| 106 | */ |
| 107 | protected int expansionMode = MULTIPLICATIVE_MODE; |
| 108 | |
| 109 | /** |
| 110 | * The initial capacity of the array. Initial capacity is not exposed as a |
| 111 | * property as it is only meaningful when passed to a constructor. |
| 112 | */ |
| 113 | protected int initialCapacity = 16; |
| 114 | |
| 115 | /** |
| 116 | * The internal storage array. |
| 117 | */ |
| 118 | protected double[] internalArray; |
| 119 | |
| 120 | /** |
| 121 | * The number of addressable elements in the array. Note that this |
| 122 | * has nothing to do with the length of the internal storage array. |
| 123 | */ |
| 124 | protected int numElements = 0; |
| 125 | |
| 126 | /** |
| 127 | * The position of the first addressable element in the internal storage |
| 128 | * array. The addressable elements in the array are <code> |
| 129 | * internalArray[startIndex],...,internalArray[startIndex + numElements -1] |
| 130 | * </code> |
| 131 | */ |
| 132 | protected int startIndex = 0; |
| 133 | |
| 134 | /** |
| 135 | * Create a ResizableArray with default properties. |
| 136 | * <ul> |
| 137 | * <li><code>initialCapacity = 16</code></li> |
| 138 | * <li><code>expansionMode = MULTIPLICATIVE_MODE</code></li> |
| 139 | * <li><code>expansionFactor = 2.5</code></li> |
| 140 | * <li><code>contractionFactor = 2.0</code></li> |
| 141 | * </ul> |
| 142 | */ |
| 143 | public ResizableDoubleArray() { |
| 144 | internalArray = new double[initialCapacity]; |
| 145 | } |
| 146 | |
| 147 | /** |
| 148 | * Create a ResizableArray with the specified initial capacity. Other |
| 149 | * properties take default values: |
| 150 | * <ul> |
| 151 | * <li><code>expansionMode = MULTIPLICATIVE_MODE</code></li> |
| 152 | * <li><code>expansionFactor = 2.5</code></li> |
| 153 | * <li><code>contractionFactor = 2.0</code></li> |
| 154 | * </ul> |
| 155 | * @param initialCapacity The initial size of the internal storage array |
| 156 | * @throws IllegalArgumentException if initialCapacity is not > 0 |
| 157 | */ |
| 158 | public ResizableDoubleArray(int initialCapacity) { |
| 159 | setInitialCapacity(initialCapacity); |
| 160 | internalArray = new double[this.initialCapacity]; |
| 161 | } |
| 162 | |
| 163 | /** |
| 164 | * Create a ResizableArray from an existing double[] with the |
| 165 | * initial capacity and numElements corresponding to the size of |
| 166 | * the supplied double[] array. If the supplied array is null, a |
| 167 | * new empty array with the default initial capacity will be created. |
| 168 | * The input array is copied, not referenced. |
| 169 | * Other properties take default values: |
| 170 | * <ul> |
| 171 | * <li><code>initialCapacity = 16</code></li> |
| 172 | * <li><code>expansionMode = MULTIPLICATIVE_MODE</code></li> |
| 173 | * <li><code>expansionFactor = 2.5</code></li> |
| 174 | * <li><code>contractionFactor = 2.0</code></li> |
| 175 | * </ul> |
| 176 | * |
| 177 | * @param initialArray initial array |
| 178 | * @since 2.2 |
| 179 | */ |
| 180 | public ResizableDoubleArray(double[] initialArray) { |
| 181 | if (initialArray == null) { |
| 182 | this.internalArray = new double[initialCapacity]; |
| 183 | } else { |
| 184 | this.internalArray = new double[initialArray.length]; |
| 185 | System.arraycopy(initialArray, 0, this.internalArray, 0, initialArray.length); |
| 186 | initialCapacity = initialArray.length; |
| 187 | numElements = initialArray.length; |
| 188 | } |
| 189 | } |
| 190 | |
| 191 | /** |
| 192 | * <p> |
| 193 | * Create a ResizableArray with the specified initial capacity |
| 194 | * and expansion factor. The remaining properties take default |
| 195 | * values: |
| 196 | * <ul> |
| 197 | * <li><code>expansionMode = MULTIPLICATIVE_MODE</code></li> |
| 198 | * <li><code>contractionFactor = 0.5 + expansionFactor</code></li> |
| 199 | * </ul></p> |
| 200 | * <p> |
| 201 | * Throws IllegalArgumentException if the following conditions are |
| 202 | * not met: |
| 203 | * <ul> |
| 204 | * <li><code>initialCapacity > 0</code></li> |
| 205 | * <li><code>expansionFactor > 1</code></li> |
| 206 | * </ul></p> |
| 207 | * |
| 208 | * @param initialCapacity The initial size of the internal storage array |
| 209 | * @param expansionFactor the array will be expanded based on this |
| 210 | * parameter |
| 211 | * @throws IllegalArgumentException if parameters are not valid |
| 212 | */ |
| 213 | public ResizableDoubleArray(int initialCapacity, float expansionFactor) { |
| 214 | this.expansionFactor = expansionFactor; |
| 215 | setInitialCapacity(initialCapacity); |
| 216 | internalArray = new double[initialCapacity]; |
| 217 | setContractionCriteria(expansionFactor +0.5f); |
| 218 | } |
| 219 | |
| 220 | /** |
| 221 | * <p> |
| 222 | * Create a ResizableArray with the specified initialCapacity, |
| 223 | * expansionFactor, and contractionCriteria. The <code>expansionMode</code> |
| 224 | * will default to <code>MULTIPLICATIVE_MODE.</code></p> |
| 225 | * <p> |
| 226 | * Throws IllegalArgumentException if the following conditions are |
| 227 | * not met: |
| 228 | * <ul> |
| 229 | * <li><code>initialCapacity > 0</code></li> |
| 230 | * <li><code>expansionFactor > 1</code></li> |
| 231 | * <li><code>contractionFactor >= expansionFactor</code></li> |
| 232 | * </ul></p> |
| 233 | * @param initialCapacity The initial size of the internal storage array |
| 234 | * @param expansionFactor the array will be expanded based on this |
| 235 | * parameter |
| 236 | * @param contractionCriteria The contraction Criteria. |
| 237 | * @throws IllegalArgumentException if parameters are not valid |
| 238 | */ |
| 239 | public ResizableDoubleArray(int initialCapacity, float expansionFactor, |
| 240 | float contractionCriteria) { |
| 241 | this.expansionFactor = expansionFactor; |
| 242 | setContractionCriteria(contractionCriteria); |
| 243 | setInitialCapacity(initialCapacity); |
| 244 | internalArray = new double[initialCapacity]; |
| 245 | } |
| 246 | |
| 247 | /** |
| 248 | * <p> |
| 249 | * Create a ResizableArray with the specified properties.</p> |
| 250 | * <p> |
| 251 | * Throws IllegalArgumentException if the following conditions are |
| 252 | * not met: |
| 253 | * <ul> |
| 254 | * <li><code>initialCapacity > 0</code></li> |
| 255 | * <li><code>expansionFactor > 1</code></li> |
| 256 | * <li><code>contractionFactor >= expansionFactor</code></li> |
| 257 | * <li><code>expansionMode in {MULTIPLICATIVE_MODE, ADDITIVE_MODE}</code> |
| 258 | * </li> |
| 259 | * </ul></p> |
| 260 | * |
| 261 | * @param initialCapacity the initial size of the internal storage array |
| 262 | * @param expansionFactor the array will be expanded based on this |
| 263 | * parameter |
| 264 | * @param contractionCriteria the contraction Criteria |
| 265 | * @param expansionMode the expansion mode |
| 266 | * @throws IllegalArgumentException if parameters are not valid |
| 267 | */ |
| 268 | public ResizableDoubleArray(int initialCapacity, float expansionFactor, |
| 269 | float contractionCriteria, int expansionMode) { |
| 270 | this.expansionFactor = expansionFactor; |
| 271 | setContractionCriteria(contractionCriteria); |
| 272 | setInitialCapacity(initialCapacity); |
| 273 | setExpansionMode(expansionMode); |
| 274 | internalArray = new double[initialCapacity]; |
| 275 | } |
| 276 | |
| 277 | /** |
| 278 | * Copy constructor. Creates a new ResizableDoubleArray that is a deep, |
| 279 | * fresh copy of the original. Needs to acquire synchronization lock |
| 280 | * on original. Original may not be null; otherwise a NullPointerException |
| 281 | * is thrown. |
| 282 | * |
| 283 | * @param original array to copy |
| 284 | * @since 2.0 |
| 285 | */ |
| 286 | public ResizableDoubleArray(ResizableDoubleArray original) { |
| 287 | copy(original, this); |
| 288 | } |
| 289 | |
| 290 | /** |
| 291 | * Adds an element to the end of this expandable array. |
| 292 | * |
| 293 | * @param value to be added to end of array |
| 294 | */ |
| 295 | public synchronized void addElement(double value) { |
| 296 | numElements++; |
| 297 | if ((startIndex + numElements) > internalArray.length) { |
| 298 | expand(); |
| 299 | } |
| 300 | internalArray[startIndex + (numElements - 1)] = value; |
| 301 | if (shouldContract()) { |
| 302 | contract(); |
| 303 | } |
| 304 | } |
| 305 | |
| 306 | /** |
| 307 | * Adds several element to the end of this expandable array. |
| 308 | * |
| 309 | * @param values to be added to end of array |
| 310 | * @since 2.2 |
| 311 | */ |
| 312 | public synchronized void addElements(double[] values) { |
| 313 | final double[] tempArray = new double[numElements + values.length + 1]; |
| 314 | System.arraycopy(internalArray, startIndex, tempArray, 0, numElements); |
| 315 | System.arraycopy(values, 0, tempArray, numElements, values.length); |
| 316 | internalArray = tempArray; |
| 317 | startIndex = 0; |
| 318 | numElements += values.length; |
| 319 | } |
| 320 | |
| 321 | /** |
| 322 | * <p> |
| 323 | * Adds an element to the end of the array and removes the first |
| 324 | * element in the array. Returns the discarded first element. |
| 325 | * The effect is similar to a push operation in a FIFO queue. |
| 326 | * </p> |
| 327 | * <p> |
| 328 | * Example: If the array contains the elements 1, 2, 3, 4 (in that order) |
| 329 | * and addElementRolling(5) is invoked, the result is an array containing |
| 330 | * the entries 2, 3, 4, 5 and the value returned is 1. |
| 331 | * </p> |
| 332 | * |
| 333 | * @param value the value to be added to the array |
| 334 | * @return the value which has been discarded or "pushed" out of the array |
| 335 | * by this rolling insert |
| 336 | */ |
| 337 | public synchronized double addElementRolling(double value) { |
| 338 | double discarded = internalArray[startIndex]; |
| 339 | |
| 340 | if ((startIndex + (numElements + 1)) > internalArray.length) { |
| 341 | expand(); |
| 342 | } |
| 343 | // Increment the start index |
| 344 | startIndex += 1; |
| 345 | |
| 346 | // Add the new value |
| 347 | internalArray[startIndex + (numElements - 1)] = value; |
| 348 | |
| 349 | // Check the contraction criteria |
| 350 | if (shouldContract()) { |
| 351 | contract(); |
| 352 | } |
| 353 | return discarded; |
| 354 | } |
| 355 | |
| 356 | /** |
| 357 | * Substitutes <code>value</code> for the most recently added value. |
| 358 | * Returns the value that has been replaced. If the array is empty (i.e. |
| 359 | * if {@link #numElements} is zero), a MathRuntimeException is thrown. |
| 360 | * |
| 361 | * @param value new value to substitute for the most recently added value |
| 362 | * @return value that has been replaced in the array |
| 363 | * @since 2.0 |
| 364 | */ |
| 365 | public synchronized double substituteMostRecentElement(double value) { |
| 366 | if (numElements < 1) { |
| 367 | throw MathRuntimeException.createArrayIndexOutOfBoundsException( |
| 368 | LocalizedFormats.CANNOT_SUBSTITUTE_ELEMENT_FROM_EMPTY_ARRAY); |
| 369 | } |
| 370 | |
| 371 | double discarded = internalArray[startIndex + (numElements - 1)]; |
| 372 | |
| 373 | internalArray[startIndex + (numElements - 1)] = value; |
| 374 | |
| 375 | return discarded; |
| 376 | } |
| 377 | |
| 378 | |
| 379 | /** |
| 380 | * Checks the expansion factor and the contraction criteria and throws an |
| 381 | * IllegalArgumentException if the contractionCriteria is less than the |
| 382 | * expansionCriteria |
| 383 | * |
| 384 | * @param expansion factor to be checked |
| 385 | * @param contraction criteria to be checked |
| 386 | * @throws IllegalArgumentException if the contractionCriteria is less than |
| 387 | * the expansionCriteria. |
| 388 | */ |
| 389 | protected void checkContractExpand(float contraction, float expansion) { |
| 390 | |
| 391 | if (contraction < expansion) { |
| 392 | throw MathRuntimeException.createIllegalArgumentException( |
| 393 | LocalizedFormats.CONTRACTION_CRITERIA_SMALLER_THAN_EXPANSION_FACTOR, |
| 394 | contraction, expansion); |
| 395 | } |
| 396 | |
| 397 | if (contraction <= 1.0) { |
| 398 | throw MathRuntimeException.createIllegalArgumentException( |
| 399 | LocalizedFormats.CONTRACTION_CRITERIA_SMALLER_THAN_ONE, |
| 400 | contraction); |
| 401 | } |
| 402 | |
| 403 | if (expansion <= 1.0) { |
| 404 | throw MathRuntimeException.createIllegalArgumentException( |
| 405 | LocalizedFormats.EXPANSION_FACTOR_SMALLER_THAN_ONE, |
| 406 | expansion); |
| 407 | } |
| 408 | } |
| 409 | |
| 410 | /** |
| 411 | * Clear the array, reset the size to the initialCapacity and the number |
| 412 | * of elements to zero. |
| 413 | */ |
| 414 | public synchronized void clear() { |
| 415 | numElements = 0; |
| 416 | startIndex = 0; |
| 417 | internalArray = new double[initialCapacity]; |
| 418 | } |
| 419 | |
| 420 | /** |
| 421 | * Contracts the storage array to the (size of the element set) + 1 - to |
| 422 | * avoid a zero length array. This function also resets the startIndex to |
| 423 | * zero. |
| 424 | */ |
| 425 | public synchronized void contract() { |
| 426 | double[] tempArray = new double[numElements + 1]; |
| 427 | |
| 428 | // Copy and swap - copy only the element array from the src array. |
| 429 | System.arraycopy(internalArray, startIndex, tempArray, 0, numElements); |
| 430 | internalArray = tempArray; |
| 431 | |
| 432 | // Reset the start index to zero |
| 433 | startIndex = 0; |
| 434 | } |
| 435 | |
| 436 | /** |
| 437 | * Discards the <code>i<code> initial elements of the array. For example, |
| 438 | * if the array contains the elements 1,2,3,4, invoking |
| 439 | * <code>discardFrontElements(2)</code> will cause the first two elements |
| 440 | * to be discarded, leaving 3,4 in the array. Throws illegalArgumentException |
| 441 | * if i exceeds numElements. |
| 442 | * |
| 443 | * @param i the number of elements to discard from the front of the array |
| 444 | * @throws IllegalArgumentException if i is greater than numElements. |
| 445 | * @since 2.0 |
| 446 | */ |
| 447 | public synchronized void discardFrontElements(int i) { |
| 448 | |
| 449 | discardExtremeElements(i,true); |
| 450 | |
| 451 | } |
| 452 | |
| 453 | /** |
| 454 | * Discards the <code>i<code> last elements of the array. For example, |
| 455 | * if the array contains the elements 1,2,3,4, invoking |
| 456 | * <code>discardMostRecentElements(2)</code> will cause the last two elements |
| 457 | * to be discarded, leaving 1,2 in the array. Throws illegalArgumentException |
| 458 | * if i exceeds numElements. |
| 459 | * |
| 460 | * @param i the number of elements to discard from the end of the array |
| 461 | * @throws IllegalArgumentException if i is greater than numElements. |
| 462 | * @since 2.0 |
| 463 | */ |
| 464 | public synchronized void discardMostRecentElements(int i) { |
| 465 | |
| 466 | discardExtremeElements(i,false); |
| 467 | |
| 468 | } |
| 469 | |
| 470 | /** |
| 471 | * Discards the <code>i<code> first or last elements of the array, |
| 472 | * depending on the value of <code>front</code>. |
| 473 | * For example, if the array contains the elements 1,2,3,4, invoking |
| 474 | * <code>discardExtremeElements(2,false)</code> will cause the last two elements |
| 475 | * to be discarded, leaving 1,2 in the array. |
| 476 | * For example, if the array contains the elements 1,2,3,4, invoking |
| 477 | * <code>discardExtremeElements(2,true)</code> will cause the first two elements |
| 478 | * to be discarded, leaving 3,4 in the array. |
| 479 | * Throws illegalArgumentException |
| 480 | * if i exceeds numElements. |
| 481 | * |
| 482 | * @param i the number of elements to discard from the front/end of the array |
| 483 | * @param front true if elements are to be discarded from the front |
| 484 | * of the array, false if elements are to be discarded from the end |
| 485 | * of the array |
| 486 | * @throws IllegalArgumentException if i is greater than numElements. |
| 487 | * @since 2.0 |
| 488 | */ |
| 489 | private synchronized void discardExtremeElements(int i,boolean front) { |
| 490 | if (i > numElements) { |
| 491 | throw MathRuntimeException.createIllegalArgumentException( |
| 492 | LocalizedFormats.TOO_MANY_ELEMENTS_TO_DISCARD_FROM_ARRAY, |
| 493 | i, numElements); |
| 494 | } else if (i < 0) { |
| 495 | throw MathRuntimeException.createIllegalArgumentException( |
| 496 | LocalizedFormats.CANNOT_DISCARD_NEGATIVE_NUMBER_OF_ELEMENTS, |
| 497 | i); |
| 498 | } else { |
| 499 | // "Subtract" this number of discarded from numElements |
| 500 | numElements -= i; |
| 501 | if (front) startIndex += i; |
| 502 | } |
| 503 | if (shouldContract()) { |
| 504 | contract(); |
| 505 | } |
| 506 | } |
| 507 | |
| 508 | /** |
| 509 | * Expands the internal storage array using the expansion factor. |
| 510 | * <p> |
| 511 | * if <code>expansionMode</code> is set to MULTIPLICATIVE_MODE, |
| 512 | * the new array size will be <code>internalArray.length * expansionFactor.</code> |
| 513 | * If <code>expansionMode</code> is set to ADDITIVE_MODE, the length |
| 514 | * after expansion will be <code>internalArray.length + expansionFactor</code> |
| 515 | * </p> |
| 516 | */ |
| 517 | protected synchronized void expand() { |
| 518 | |
| 519 | // notice the use of FastMath.ceil(), this guarantees that we will always |
| 520 | // have an array of at least currentSize + 1. Assume that the |
| 521 | // current initial capacity is 1 and the expansion factor |
| 522 | // is 1.000000000000000001. The newly calculated size will be |
| 523 | // rounded up to 2 after the multiplication is performed. |
| 524 | int newSize = 0; |
| 525 | if (expansionMode == MULTIPLICATIVE_MODE) { |
| 526 | newSize = (int) FastMath.ceil(internalArray.length * expansionFactor); |
| 527 | } else { |
| 528 | newSize = internalArray.length + FastMath.round(expansionFactor); |
| 529 | } |
| 530 | double[] tempArray = new double[newSize]; |
| 531 | |
| 532 | // Copy and swap |
| 533 | System.arraycopy(internalArray, 0, tempArray, 0, internalArray.length); |
| 534 | internalArray = tempArray; |
| 535 | } |
| 536 | |
| 537 | /** |
| 538 | * Expands the internal storage array to the specified size. |
| 539 | * |
| 540 | * @param size Size of the new internal storage array |
| 541 | */ |
| 542 | private synchronized void expandTo(int size) { |
| 543 | double[] tempArray = new double[size]; |
| 544 | // Copy and swap |
| 545 | System.arraycopy(internalArray, 0, tempArray, 0, internalArray.length); |
| 546 | internalArray = tempArray; |
| 547 | } |
| 548 | |
| 549 | /** |
| 550 | * The contraction criteria defines when the internal array will contract |
| 551 | * to store only the number of elements in the element array. |
| 552 | * If the <code>expansionMode</code> is <code>MULTIPLICATIVE_MODE</code>, |
| 553 | * contraction is triggered when the ratio between storage array length |
| 554 | * and <code>numElements</code> exceeds <code>contractionFactor</code>. |
| 555 | * If the <code>expansionMode</code> is <code>ADDITIVE_MODE</code>, the |
| 556 | * number of excess storage locations is compared to |
| 557 | * <code>contractionFactor.</code> |
| 558 | * |
| 559 | * @return the contraction criteria used to reclaim memory. |
| 560 | */ |
| 561 | public float getContractionCriteria() { |
| 562 | return contractionCriteria; |
| 563 | } |
| 564 | |
| 565 | /** |
| 566 | * Returns the element at the specified index |
| 567 | * |
| 568 | * @param index index to fetch a value from |
| 569 | * @return value stored at the specified index |
| 570 | * @throws ArrayIndexOutOfBoundsException if <code>index</code> is less than |
| 571 | * zero or is greater than <code>getNumElements() - 1</code>. |
| 572 | */ |
| 573 | public synchronized double getElement(int index) { |
| 574 | if (index >= numElements) { |
| 575 | throw MathRuntimeException.createArrayIndexOutOfBoundsException( |
| 576 | LocalizedFormats.INDEX_LARGER_THAN_MAX, |
| 577 | index, numElements - 1); |
| 578 | } else if (index >= 0) { |
| 579 | return internalArray[startIndex + index]; |
| 580 | } else { |
| 581 | throw MathRuntimeException.createArrayIndexOutOfBoundsException( |
| 582 | LocalizedFormats.CANNOT_RETRIEVE_AT_NEGATIVE_INDEX, |
| 583 | index); |
| 584 | } |
| 585 | } |
| 586 | |
| 587 | /** |
| 588 | * Returns a double array containing the elements of this |
| 589 | * <code>ResizableArray</code>. This method returns a copy, not a |
| 590 | * reference to the underlying array, so that changes made to the returned |
| 591 | * array have no effect on this <code>ResizableArray.</code> |
| 592 | * @return the double array. |
| 593 | */ |
| 594 | public synchronized double[] getElements() { |
| 595 | double[] elementArray = new double[numElements]; |
| 596 | System.arraycopy( internalArray, startIndex, elementArray, 0, |
| 597 | numElements); |
| 598 | return elementArray; |
| 599 | } |
| 600 | |
| 601 | /** |
| 602 | * The expansion factor controls the size of a new array when an array |
| 603 | * needs to be expanded. The <code>expansionMode</code> |
| 604 | * determines whether the size of the array is multiplied by the |
| 605 | * <code>expansionFactor</code> (MULTIPLICATIVE_MODE) or if |
| 606 | * the expansion is additive (ADDITIVE_MODE -- <code>expansionFactor</code> |
| 607 | * storage locations added). The default <code>expansionMode</code> is |
| 608 | * MULTIPLICATIVE_MODE and the default <code>expansionFactor</code> |
| 609 | * is 2.0. |
| 610 | * |
| 611 | * @return the expansion factor of this expandable double array |
| 612 | */ |
| 613 | public float getExpansionFactor() { |
| 614 | return expansionFactor; |
| 615 | } |
| 616 | |
| 617 | /** |
| 618 | * The <code>expansionMode</code> determines whether the internal storage |
| 619 | * array grows additively (ADDITIVE_MODE) or multiplicatively |
| 620 | * (MULTIPLICATIVE_MODE) when it is expanded. |
| 621 | * |
| 622 | * @return Returns the expansionMode. |
| 623 | */ |
| 624 | public int getExpansionMode() { |
| 625 | return expansionMode; |
| 626 | } |
| 627 | |
| 628 | /** |
| 629 | * Notice the package scope on this method. This method is simply here |
| 630 | * for the JUnit test, it allows us check if the expansion is working |
| 631 | * properly after a number of expansions. This is not meant to be a part |
| 632 | * of the public interface of this class. |
| 633 | * |
| 634 | * @return the length of the internal storage array. |
| 635 | */ |
| 636 | synchronized int getInternalLength() { |
| 637 | return internalArray.length; |
| 638 | } |
| 639 | |
| 640 | /** |
| 641 | * Returns the number of elements currently in the array. Please note |
| 642 | * that this is different from the length of the internal storage array. |
| 643 | * |
| 644 | * @return number of elements |
| 645 | */ |
| 646 | public synchronized int getNumElements() { |
| 647 | return numElements; |
| 648 | } |
| 649 | |
| 650 | /** |
| 651 | * Returns the internal storage array. Note that this method returns |
| 652 | * a reference to the internal storage array, not a copy, and to correctly |
| 653 | * address elements of the array, the <code>startIndex</code> is |
| 654 | * required (available via the {@link #start} method). This method should |
| 655 | * only be used in cases where copying the internal array is not practical. |
| 656 | * The {@link #getElements} method should be used in all other cases. |
| 657 | * |
| 658 | * |
| 659 | * @return the internal storage array used by this object |
| 660 | * @deprecated replaced by {@link #getInternalValues()} as of 2.0 |
| 661 | */ |
| 662 | @Deprecated |
| 663 | public synchronized double[] getValues() { |
| 664 | return internalArray; |
| 665 | } |
| 666 | |
| 667 | /** |
| 668 | * Returns the internal storage array. Note that this method returns |
| 669 | * a reference to the internal storage array, not a copy, and to correctly |
| 670 | * address elements of the array, the <code>startIndex</code> is |
| 671 | * required (available via the {@link #start} method). This method should |
| 672 | * only be used in cases where copying the internal array is not practical. |
| 673 | * The {@link #getElements} method should be used in all other cases. |
| 674 | * |
| 675 | * |
| 676 | * @return the internal storage array used by this object |
| 677 | * @since 2.0 |
| 678 | */ |
| 679 | public synchronized double[] getInternalValues() { |
| 680 | return internalArray; |
| 681 | } |
| 682 | |
| 683 | /** |
| 684 | * Sets the contraction criteria for this ExpandContractDoubleArray. |
| 685 | * |
| 686 | * @param contractionCriteria contraction criteria |
| 687 | */ |
| 688 | public void setContractionCriteria(float contractionCriteria) { |
| 689 | checkContractExpand(contractionCriteria, getExpansionFactor()); |
| 690 | synchronized(this) { |
| 691 | this.contractionCriteria = contractionCriteria; |
| 692 | } |
| 693 | } |
| 694 | |
| 695 | |
| 696 | /** |
| 697 | * Sets the element at the specified index. If the specified index is greater than |
| 698 | * <code>getNumElements() - 1</code>, the <code>numElements</code> property |
| 699 | * is increased to <code>index +1</code> and additional storage is allocated |
| 700 | * (if necessary) for the new element and all (uninitialized) elements |
| 701 | * between the new element and the previous end of the array). |
| 702 | * |
| 703 | * @param index index to store a value in |
| 704 | * @param value value to store at the specified index |
| 705 | * @throws ArrayIndexOutOfBoundsException if <code>index</code> is less than |
| 706 | * zero. |
| 707 | */ |
| 708 | public synchronized void setElement(int index, double value) { |
| 709 | if (index < 0) { |
| 710 | throw MathRuntimeException.createArrayIndexOutOfBoundsException( |
| 711 | LocalizedFormats.CANNOT_SET_AT_NEGATIVE_INDEX, |
| 712 | index); |
| 713 | } |
| 714 | if (index + 1 > numElements) { |
| 715 | numElements = index + 1; |
| 716 | } |
| 717 | if ((startIndex + index) >= internalArray.length) { |
| 718 | expandTo(startIndex + (index + 1)); |
| 719 | } |
| 720 | internalArray[startIndex + index] = value; |
| 721 | } |
| 722 | |
| 723 | /** |
| 724 | * Sets the expansionFactor. Throws IllegalArgumentException if the |
| 725 | * the following conditions are not met: |
| 726 | * <ul> |
| 727 | * <li><code>expansionFactor > 1</code></li> |
| 728 | * <li><code>contractionFactor >= expansionFactor</code></li> |
| 729 | * </ul> |
| 730 | * @param expansionFactor the new expansion factor value. |
| 731 | * @throws IllegalArgumentException if expansionFactor is <= 1 or greater |
| 732 | * than contractionFactor |
| 733 | */ |
| 734 | public void setExpansionFactor(float expansionFactor) { |
| 735 | checkContractExpand(getContractionCriteria(), expansionFactor); |
| 736 | // The check above verifies that the expansion factor is > 1.0; |
| 737 | synchronized(this) { |
| 738 | this.expansionFactor = expansionFactor; |
| 739 | } |
| 740 | } |
| 741 | |
| 742 | /** |
| 743 | * Sets the <code>expansionMode</code>. The specified value must be one of |
| 744 | * ADDITIVE_MODE, MULTIPLICATIVE_MODE. |
| 745 | * |
| 746 | * @param expansionMode The expansionMode to set. |
| 747 | * @throws IllegalArgumentException if the specified mode value is not valid |
| 748 | */ |
| 749 | public void setExpansionMode(int expansionMode) { |
| 750 | if (expansionMode != MULTIPLICATIVE_MODE && |
| 751 | expansionMode != ADDITIVE_MODE) { |
| 752 | throw MathRuntimeException.createIllegalArgumentException( |
| 753 | LocalizedFormats.UNSUPPORTED_EXPANSION_MODE, |
| 754 | expansionMode, MULTIPLICATIVE_MODE, "MULTIPLICATIVE_MODE", |
| 755 | ADDITIVE_MODE, "ADDITIVE_MODE"); |
| 756 | } |
| 757 | synchronized(this) { |
| 758 | this.expansionMode = expansionMode; |
| 759 | } |
| 760 | } |
| 761 | |
| 762 | /** |
| 763 | * Sets the initial capacity. Should only be invoked by constructors. |
| 764 | * |
| 765 | * @param initialCapacity of the array |
| 766 | * @throws IllegalArgumentException if <code>initialCapacity</code> is not |
| 767 | * positive. |
| 768 | */ |
| 769 | protected void setInitialCapacity(int initialCapacity) { |
| 770 | if (initialCapacity > 0) { |
| 771 | synchronized(this) { |
| 772 | this.initialCapacity = initialCapacity; |
| 773 | } |
| 774 | } else { |
| 775 | throw MathRuntimeException.createIllegalArgumentException( |
| 776 | LocalizedFormats.INITIAL_CAPACITY_NOT_POSITIVE, |
| 777 | initialCapacity); |
| 778 | } |
| 779 | } |
| 780 | |
| 781 | /** |
| 782 | * This function allows you to control the number of elements contained |
| 783 | * in this array, and can be used to "throw out" the last n values in an |
| 784 | * array. This function will also expand the internal array as needed. |
| 785 | * |
| 786 | * @param i a new number of elements |
| 787 | * @throws IllegalArgumentException if <code>i</code> is negative. |
| 788 | */ |
| 789 | public synchronized void setNumElements(int i) { |
| 790 | |
| 791 | // If index is negative thrown an error |
| 792 | if (i < 0) { |
| 793 | throw MathRuntimeException.createIllegalArgumentException( |
| 794 | LocalizedFormats.INDEX_NOT_POSITIVE, |
| 795 | i); |
| 796 | } |
| 797 | |
| 798 | // Test the new num elements, check to see if the array needs to be |
| 799 | // expanded to accommodate this new number of elements |
| 800 | if ((startIndex + i) > internalArray.length) { |
| 801 | expandTo(startIndex + i); |
| 802 | } |
| 803 | |
| 804 | // Set the new number of elements to new value |
| 805 | numElements = i; |
| 806 | } |
| 807 | |
| 808 | /** |
| 809 | * Returns true if the internal storage array has too many unused |
| 810 | * storage positions. |
| 811 | * |
| 812 | * @return true if array satisfies the contraction criteria |
| 813 | */ |
| 814 | private synchronized boolean shouldContract() { |
| 815 | if (expansionMode == MULTIPLICATIVE_MODE) { |
| 816 | return (internalArray.length / ((float) numElements)) > contractionCriteria; |
| 817 | } else { |
| 818 | return (internalArray.length - numElements) > contractionCriteria; |
| 819 | } |
| 820 | } |
| 821 | |
| 822 | /** |
| 823 | * Returns the starting index of the internal array. The starting index is |
| 824 | * the position of the first addressable element in the internal storage |
| 825 | * array. The addressable elements in the array are <code> |
| 826 | * internalArray[startIndex],...,internalArray[startIndex + numElements -1] |
| 827 | * </code> |
| 828 | * |
| 829 | * @return starting index |
| 830 | */ |
| 831 | public synchronized int start() { |
| 832 | return startIndex; |
| 833 | } |
| 834 | |
| 835 | /** |
| 836 | * <p>Copies source to dest, copying the underlying data, so dest is |
| 837 | * a new, independent copy of source. Does not contract before |
| 838 | * the copy.</p> |
| 839 | * |
| 840 | * <p>Obtains synchronization locks on both source and dest |
| 841 | * (in that order) before performing the copy.</p> |
| 842 | * |
| 843 | * <p>Neither source nor dest may be null; otherwise a NullPointerException |
| 844 | * is thrown</p> |
| 845 | * |
| 846 | * @param source ResizableDoubleArray to copy |
| 847 | * @param dest ResizableArray to replace with a copy of the source array |
| 848 | * @since 2.0 |
| 849 | * |
| 850 | */ |
| 851 | public static void copy(ResizableDoubleArray source, ResizableDoubleArray dest) { |
| 852 | synchronized(source) { |
| 853 | synchronized(dest) { |
| 854 | dest.initialCapacity = source.initialCapacity; |
| 855 | dest.contractionCriteria = source.contractionCriteria; |
| 856 | dest.expansionFactor = source.expansionFactor; |
| 857 | dest.expansionMode = source.expansionMode; |
| 858 | dest.internalArray = new double[source.internalArray.length]; |
| 859 | System.arraycopy(source.internalArray, 0, dest.internalArray, |
| 860 | 0, dest.internalArray.length); |
| 861 | dest.numElements = source.numElements; |
| 862 | dest.startIndex = source.startIndex; |
| 863 | } |
| 864 | } |
| 865 | } |
| 866 | |
| 867 | /** |
| 868 | * Returns a copy of the ResizableDoubleArray. Does not contract before |
| 869 | * the copy, so the returned object is an exact copy of this. |
| 870 | * |
| 871 | * @return a new ResizableDoubleArray with the same data and configuration |
| 872 | * properties as this |
| 873 | * @since 2.0 |
| 874 | */ |
| 875 | public synchronized ResizableDoubleArray copy() { |
| 876 | ResizableDoubleArray result = new ResizableDoubleArray(); |
| 877 | copy(this, result); |
| 878 | return result; |
| 879 | } |
| 880 | |
| 881 | /** |
| 882 | * Returns true iff object is a ResizableDoubleArray with the same properties |
| 883 | * as this and an identical internal storage array. |
| 884 | * |
| 885 | * @param object object to be compared for equality with this |
| 886 | * @return true iff object is a ResizableDoubleArray with the same data and |
| 887 | * properties as this |
| 888 | * @since 2.0 |
| 889 | */ |
| 890 | @Override |
| 891 | public boolean equals(Object object) { |
| 892 | if (object == this ) { |
| 893 | return true; |
| 894 | } |
| 895 | if (object instanceof ResizableDoubleArray == false) { |
| 896 | return false; |
| 897 | } |
| 898 | synchronized(this) { |
| 899 | synchronized(object) { |
| 900 | boolean result = true; |
| 901 | ResizableDoubleArray other = (ResizableDoubleArray) object; |
| 902 | result = result && (other.initialCapacity == initialCapacity); |
| 903 | result = result && (other.contractionCriteria == contractionCriteria); |
| 904 | result = result && (other.expansionFactor == expansionFactor); |
| 905 | result = result && (other.expansionMode == expansionMode); |
| 906 | result = result && (other.numElements == numElements); |
| 907 | result = result && (other.startIndex == startIndex); |
| 908 | if (!result) { |
| 909 | return false; |
| 910 | } else { |
| 911 | return Arrays.equals(internalArray, other.internalArray); |
| 912 | } |
| 913 | } |
| 914 | } |
| 915 | } |
| 916 | |
| 917 | /** |
| 918 | * Returns a hash code consistent with equals. |
| 919 | * |
| 920 | * @return hash code representing this ResizableDoubleArray |
| 921 | * @since 2.0 |
| 922 | */ |
| 923 | @Override |
| 924 | public synchronized int hashCode() { |
| 925 | int[] hashData = new int[7]; |
| 926 | hashData[0] = new Float(expansionFactor).hashCode(); |
| 927 | hashData[1] = new Float(contractionCriteria).hashCode(); |
| 928 | hashData[2] = expansionMode; |
| 929 | hashData[3] = Arrays.hashCode(internalArray); |
| 930 | hashData[4] = initialCapacity; |
| 931 | hashData[5] = numElements; |
| 932 | hashData[6] = startIndex; |
| 933 | return Arrays.hashCode(hashData); |
| 934 | } |
| 935 | |
| 936 | } |