/* ************************************************************************** * * * General Purpose Hash Function Algorithms Library * * * * Author: Arash Partow - 2002 * * URL: http://www.partow.net * * URL: http://www.partow.net/programming/hashfunctions/index.html * * * * Copyright notice: * * Free use of the General Purpose Hash Function Algorithms Library is * * permitted under the guidelines and in accordance with the most current * * version of the Common Public License. * * http://www.opensource.org/licenses/cpl1.0.php * * * ************************************************************************** */ class GeneralHashFunctionLibrary { public long RSHashCode(String str) { int b = 378551; int a = 63689; long hash = 0; for(int i = 0; i < str.length(); i++) { hash = hash * a + str.charAt(i); a = a * b; } return hash; } /* End Of RS Hash Function */ public long JSHashCode(String str) { long hash = 1315423911; for(int i = 0; i < str.length(); i++) { hash ^= ((hash << 5) + str.charAt(i) + (hash >> 2)); } return hash; } /* End Of JS Hash Function */ public long PJWHashCode(String str) { long BitsInUnsignedInt = (long)(4 * 8); long ThreeQuarters = (long)((BitsInUnsignedInt * 3) / 4); long OneEighth = (long)(BitsInUnsignedInt / 8); long HighBits = (long)(0xFFFFFFFF) << (BitsInUnsignedInt - OneEighth); long hash = 0; long test = 0; for(int i = 0; i < str.length(); i++) { hash = (hash << OneEighth) + str.charAt(i); if((test = hash & HighBits) != 0) { hash = (( hash ^ (test >> ThreeQuarters)) & (~HighBits)); } } return hash; } /* End Of P. J. Weinberger Hash Function */ public long ELFHashCode(String str) { long hash = 0; long x = 0; for(int i = 0; i < str.length(); i++) { hash = (hash << 4) + str.charAt(i); if((x = hash & 0xF0000000L) != 0) { hash ^= (x >> 24); } hash &= ~x; } return hash; } /* End Of ELF Hash Function */ public long BKDRHashCode(String str) { long seed = 131; // 31 131 1313 13131 131313 etc.. long hash = 0; for(int i = 0; i < str.length(); i++) { hash = (hash * seed) + str.charAt(i); } return hash; } /* End Of BKDR Hash Function */ public long SDBMHashCode(String str) { long hash = 0; for(int i = 0; i < str.length(); i++) { hash = str.charAt(i) + (hash << 6) + (hash << 16) - hash; } return hash; } /* End Of SDBM Hash Function */ public long DJBHashCode(String str) { long hash = 5381; for(int i = 0; i < str.length(); i++) { hash = ((hash << 5) + hash) + str.charAt(i); } return hash; } /* End Of DJB Hash Function */ public long DEKHashCode(String str) { long hash = str.length(); for(int i = 0; i < str.length(); i++) { hash = ((hash << 5) ^ (hash >> 27)) ^ str.charAt(i); } return hash; } /* End Of DEK Hash Function */ public long BPHashCode(String str) { long hash = 0; for(int i = 0; i < str.length(); i++) { hash = hash << 7 ^ str.charAt(i); } return hash; } /* End Of BP Hash Function */ public long FNVHashCode(String str) { long fnv_prime = 0x811C9DC5; long hash = 0; for(int i = 0; i < str.length(); i++) { hash *= fnv_prime; hash ^= str.charAt(i); } return hash; } /* End Of FNV Hash Function */ public long APHashCode(String str) { long hash = 0xAAAAAAAA; for(int i = 0; i < str.length(); i++) { if ((i & 1) == 0) { hash ^= ((hash << 7) ^ str.charAt(i) * (hash >> 3)); } else { hash ^= (~((hash << 11) + str.charAt(i) ^ (hash >> 5))); } } return hash; } /* End Of AP Hash Function */ }