File indexing completed on 2024-11-17 04:55:18

 /*
     SPDX-License-Identifier: MPL-2.0
 */
 
 /* Copyright (c) 2015 Brian R. Bondy. Distributed under the MPL2 license.
  * This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #include <string.h>
 #include "BloomFilter.h"
 
 BloomFilter::BloomFilter(unsigned int bitsPerElement,
     unsigned int estimatedNumElements, HashFn *hashFns, int numHashFns) :
     hashFns(nullptr), numHashFns(0), byteBufferSize(0), buffer(nullptr) {
   this->hashFns = hashFns;
   this->numHashFns = numHashFns;
   lastHashes = new uint64_t[numHashFns];
   byteBufferSize = bitsPerElement * estimatedNumElements / 8 + 1;
   bitBufferSize = byteBufferSize * 8;
   buffer = new char[byteBufferSize];
   memset(buffer, 0, byteBufferSize);
 }
 
 // Constructs a BloomFilter by copying the specified buffer and number of bytes
 BloomFilter::BloomFilter(const char *buffer, int byteBufferSize,
     HashFn *hashFns, int numHashFns) :
     hashFns(nullptr), numHashFns(0), byteBufferSize(0), buffer(nullptr) {
   this->hashFns = hashFns;
   this->numHashFns = numHashFns;
   lastHashes = new uint64_t[numHashFns];
   this->byteBufferSize = byteBufferSize;
   bitBufferSize = byteBufferSize * 8;
   this->buffer = new char[byteBufferSize];
   memcpy(this->buffer, buffer, byteBufferSize);
 }
 
 BloomFilter::~BloomFilter() {
   if (buffer) {
     delete[] buffer;
   }
   if (lastHashes) {
     delete[] lastHashes;
   }
 }
 
 void BloomFilter::setBit(unsigned int bitLocation) {
   buffer[bitLocation / 8] |= 1 << bitLocation % 8;
 }
 
 bool BloomFilter::isBitSet(unsigned int bitLocation) {
   return !!(buffer[bitLocation / 8] & 1 << bitLocation % 8);
 }
 
 void BloomFilter::add(const char *input, int len) {
   for (int j = 0; j < numHashFns; j++) {
     setBit(hashFns[j](input, len) % bitBufferSize);
   }
 }
 
 void BloomFilter::add(const char *sz) {
   add(sz, static_cast<int>(strlen(sz)));
 }
 
 bool BloomFilter::exists(const char *input, int len) {
   bool allSet = true;
   for (int j = 0; j < numHashFns; j++) {
     allSet = allSet && isBitSet(hashFns[j](input, len) % bitBufferSize);
   }
   return allSet;
 }
 
 bool BloomFilter::exists(const char *sz) {
   return exists(sz, static_cast<int>(strlen(sz)));
 }
 
 void BloomFilter::getHashesForCharCodes(const char *input, int inputLen,
     uint64_t *lastHashes, uint64_t *newHashes, unsigned char lastCharCode) {
   for (int i = 0; i < numHashFns; i++) {
     if (lastHashes) {
       *(newHashes + i) = hashFns[i](input, inputLen,
           lastCharCode, *(lastHashes+i));
     } else {
       *(newHashes + i) = hashFns[i](input, inputLen);
     }
   }
 }
 
 bool BloomFilter::substringExists(const char *data, int dataLen,
     int substringLength) {
   unsigned char lastCharCode = 0;
   for (int i = 0; i < dataLen - substringLength + 1; i++) {
     getHashesForCharCodes(data + i, substringLength, i == 0
         ? nullptr : lastHashes, lastHashes, lastCharCode);
     bool allSet = true;
     for (int j = 0; j < numHashFns; j++) {
       allSet = allSet && isBitSet(lastHashes[j] % bitBufferSize);
     }
     if (allSet) {
       return true;
     }
     lastCharCode = data[i];
   }
   return false;
 }
 
 bool BloomFilter::substringExists(const char *data, int substringLength) {
   return substringExists(data, static_cast<int>(strlen(data)), substringLength);
 }
 
 void BloomFilter::clear() {
   memset(buffer, 0, byteBufferSize);
 }