Press n or j to go to the next uncovered block, b, p or k for the previous block.
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 | /* eslint-disable no-param-reassign */ import Action from '../../components/hashes/HashTableVerticalActions'; /** * Each Row initially holds 1 DataBlock. * DataBlocks store the actual values. * If more than <blockSize> elements hash to the same DataBlock of a row, the number of DataBlocks * in this row is doubled until there is no more than <blockSize> collisions. * @constructor * @param blockSize */ function DataBlock(blockSize) { this.values = new Array(blockSize); } /** * Each Index holds y=entrySize Rows. * Each Row initially holds 1 DataBlock. * If more than <blockSize> elements hash to the same DataBlock of a row, the number of DataBlocks * in this row is doubled until there is no more than <blockSize> collisions. * @constructor */ function Row() { /** * How often this row has been extended. i.e. how often the * number of Data Blocks in this Row has been doubled. * Also known as z. * @type {number} */ this.extendCounter = 0; /** * DataBlocks. Holds 2^z DataBlocks. * @type {DataBlock[]} */ this.dataBlocks = []; } /** * There are x=indexSize Index objects in BISEH.indexes. * An Index holds y=entrySize Rows. * @constructor * @param {number} rowsPerIndex */ function Index(rowsPerIndex) { /** * @type {Row[]} */ this.rows = []; for (let i = 0; i < 2 ** rowsPerIndex; i += 1) { this.rows[i] = new Row(); } } /** * BISEH - Bounded Index Size Extendible Hashing * * BISEH uses three hash functions to find the right index area, index entry and data block. * It is characterized by a constant index size and is a new form of Extendible Hashing. * If a data block reaches its limit, then the data area is going to expand. * * A BISEH hash table consists of (x=indexSize) Indexes. * Each Index holds (y=entrySize) Rows. * Each Row initially holds (1) DataBlock. * Each DataBlock can hold (b=blockSize) values. * * All addressing is done in binary. * * If more than <blockSize> elements hash to the same DataBlock of a row, the number of DataBlocks * in this row is doubled until there is no more than <blockSize> collisions. * The number of doubles (z) is also the length of the address of the DataBlock of a Row, in bits. */ export default class BISEHCopyFromFrick { /** * Number of Indexes. Also known as x. * Power of 2, ie. number of bits of binary index address. * 2^x = number of Index() objects in BISEH.indexes. * @type {number} */ indexSize = 2; /** * Rows per Index. Also known as y. * Power of 2, ie. number of bits of binary row address within index. * 2^y = number of Row() Objects in Index.rows. * @type {number} */ entrySize = 2; /** * DataBlock Size. Also known as b. * Maximum number of values a DataBlock can hold. * @type {number} */ bucketSize = 2; /** * Consists of <indexSize> 'Index' objects. * @type {Index[]} */ indexes = []; lastInformationField = ''; /** * Initialize an empty hash table. * @param {number} indexDepth * @param {number} rowsPerIndex * @param {number} dataBlockSize */ init(indexDepth = 3, rowsPerIndex = 3, dataBlockSize = 3) { const steps = []; this.indexSize = indexDepth; this.entrySize = rowsPerIndex; this.bucketSize = dataBlockSize; console.log("Init: received: ", this.indexSize, this.entrySize, this.bucketSize); // Build fresh hash table this.indexes = []; for (let i = 0; i < 2 ** this.indexSize; i += 1) { let entrySizes = []; for(let j=0; j<2**this.entrySize; j++){ this.indexes[i] = new Index(this.entrySize); } } this.addCreationSteps(steps); return this.addUpdatedInformation(steps, indexDepth, rowsPerIndex, dataBlockSize); } /** * The Index is given by the rightmost <indexSize> bits of the binary representation of the given * value. * @param {number} value * @returns {number} */ getIndexAddress(value) { // The bitwise & of two decimal numbers returns a decimal number. // eslint-disable-next-line no-bitwise let i = value & (2 ** this.indexSize - 1); return i; } /** * The Row is given by the rightmost <entrySize> bits to the left of the <indexSize> bits of * the binary representation of the given value. * @param {number} value * @returns {number} */ getRowAddress(value) { let binaryValue = value.toString(2); binaryValue = binaryValue.slice(0, -1); binaryValue = binaryValue.slice(-this.entrySize); while (binaryValue.length < this.entrySize) { binaryValue = '0' + binaryValue; } console.log("y ", binaryValue); return binaryValue; } /** * The DataBlock is given by the rightmost <counter> bits to the left of * <indexSize+entrySize> bits of the binary representation of the given value. * The address is based on how many DataBlocks there are in a Row (counter). * @param {number} value * @param {number} counter * @returns {number} */ getDataBlockAddress(value, counter) { // <counter> 1s to the left of <indexSize+entrySize> bits const bitMask = 2 ** (this.indexSize + this.entrySize + counter) - 2 ** (this.indexSize + this.entrySize); // eslint-disable-next-line no-bitwise return value & bitMask; } /** * Extend the available space in the given Row by doubling the number of DataBlocks in the row to * accommodate more values. * todo: function BISEH.extend() needs a sanity check! * @param {Row} row */ extend(row) { const newRow = new Row(); let dataBlockAddress; row.extendCounter += 1; // loop over indexBlock for (let i = 0; i < row.dataBlocks.length; i += 1) { newRow.dataBlocks[i] = row.dataBlocks[i]; for (let j = 0; j < row.dataBlocks[i].values.length; j += 1) { if (row.dataBlocks[i].values !== undefined) { newRow.dataBlocks[i].values[j] = row.dataBlocks[i].values[j]; } } } for (let i = 0; i < 2 ** row.extendCounter; i += 1) { row.dataBlocks[i] = new DataBlock(this.bucketSize); } for (let i = 0; i < newRow.dataBlocks.length; i += 1) { for (let j = 0; j < newRow.dataBlocks[i].values.length; j += 1) { if (newRow.dataBlocks[i].values[j] !== undefined) { dataBlockAddress = this .getDataBlockAddress(newRow.dataBlocks[i].values[j], row.extendCounter); if (dataBlockAddress !== undefined) { // why/how could this be undefined? for (let k = 0; k < this.bucketSize; k += 1) { if (row.dataBlocks[dataBlockAddress].values[k] === undefined) { row.dataBlocks[dataBlockAddress].values[k] = newRow.dataBlocks[i].values[j]; break; } } } } } } } /** * Insert the given value into the hash table. * @param value */ insert(value) { const hashedIndex = this.getIndexAddress(value); const hashedDepth = this.getRowAddress(value); console.log("hashed depth: ", hashedDepth); const row = this.indexes[hashedIndex].rows[hashedDepth]; if (row.dataBlocks[0] === undefined) { row.dataBlocks[0] = new DataBlock(this.bucketSize); } // check if the value is already there let alreadyInserted = false; for (let i = 0; i < this.bucketSize; i += 1) { const dataBlockAddress = this.getDataBlockAddress(value, row.extendCounter); if (row.dataBlocks[dataBlockAddress].values[i] === value) { alreadyInserted = true; break; } } if (alreadyInserted) { return; } // value is not in the hash table, insert it. let inserted = false; for (let i = 0; i < this.bucketSize; i += 1) { // loop over all DataBlocks of the given row if (row.extendCounter === 0) { // special case: // 'row' has never been extended, therefor the dataBlockIndex is ignored. if (row.dataBlocks[0].values[i] === undefined) { // found place, insert, done. row.dataBlocks[0].values[i] = value; inserted = true; break; } } else { // 'row' was already extended, need to also consider dataBlockIndex. const dataBlockIndex = this.getDataBlockAddress(value, row.extendCounter); if ( row.dataBlocks[dataBlockIndex] !== undefined && row.dataBlocks[dataBlockIndex].values[i] === undefined ) { // found place, insert, done. row.dataBlocks[dataBlockIndex].values[i] = value; inserted = true; break; } } } if (inserted) { // done, return. return; } // value could not be inserted, extend table and insert value while (!inserted) { // extend until everything fits this.extend(row); // recalculate dataBlockIndex after extension const dataBlockIndex = this.getDataBlockAddress(value, row.extendCounter); // check all elements in the DataBlock for (let j = 0; j < this.bucketSize; j += 1) { if ( row.dataBlocks[dataBlockIndex].values[j] === undefined && row.dataBlocks[dataBlockIndex] !== undefined ) { // found place, insert, done. row.dataBlocks[dataBlockIndex].values[j] = value; inserted = true; break; } } } } /** * Search the given value in the hash table. * @param value */ search(value) { const xIndex = this.getIndexAddress(value); const yIndex = this.getRowAddress(value); const row = this.indexes[xIndex].rows[yIndex]; const dataBlockAddress = this.getDataBlockAddress(value, row.extendCounter); if (row.dataBlocks[dataBlockAddress] === undefined) { // not found. return false; } for (let i = 0; i < row.dataBlocks[dataBlockAddress].values.length; i += 1) { if (value === row.dataBlocks[dataBlockAddress].values[i]) { //found return true; } } return false; } /** * Remove the given value from the hash table. * @param value */ remove(value) { const xIndex = this.getIndexAddress(value); const yIndex = this.getRowAddress(value); const row = this.indexes[xIndex].rows[yIndex]; const dataBlockAddress = this.getDataBlockAddress(value, row.extendCounter); if (row.dataBlocks[dataBlockAddress] === undefined) { // not found. return false; } for (let i = 0; i < row.dataBlocks[dataBlockAddress].values.length; i += 1) { if (value === row.dataBlocks[dataBlockAddress].values[i]) { row.dataBlocks[dataBlockAddress].values[i] = undefined; //removed return true; } } //not removed return false; } //Visiualizing addCreationSteps(steps) { const rememberInformationField = this.lastInformationField; this.lastInformationField = 'Initialized with indexSize ' + this.indexSize + ', entrySize ' + this.entrySize + ' and bucketSize ' + this.bucketSize; steps.push({ do: [ { action: Action.CREATE_LIST, indexDepth: this.indexSize, entryDepth: this.entrySize, bucketSize: this.bucketSize, }, { action: Action.UPDATE_INFO_BOX, text: this.lastInformationField, },], undo: [ { action: Action.DELETE_LIST, }, { action: Action.SET_INFORMATION_FIELD, text: rememberInformationField, }, ], }); } addUpdatedInformation(steps, indexDepth, rowsPerIndex, dataBlockSize) { this.lastInformationField = "Initialized with indexSize: " + indexDepth + ", entryDepths: " + rowsPerIndex + ", bucket size: " + dataBlockSize; steps.push({ do: [ { action: Action.SET_INFORMATION_FIELD, text: this.lastInformationField, }, { action: Action.SET_HASH_CALCULATION, indexDepth: indexDepth, entryDepth: rowsPerIndex, bucketSize: dataBlockSize, }, ], undo: [ { action: Action.DELETE_LIST, }, { action: Action.SET_INFORMATION_FIELD, text: '', }, { action: Action.SET_HASH_CALCULATION, text: null, }, ], }); return steps; } } |