com.tomgibara.hashing

Interface Hasher<T>

Type Parameters:

T - the type of object for which hashes are generated

All Superinterfaces:

Hashing<T>

public interface Hasher<T>
extends Hashing<T>

Implementations of this interface generate hash codes from objects. Depending upon the implementation, null values may be supported.

Author:

Tom Gibara

Method Summary

Modifier and Type	Method and Description
default Hasher<T>	distinct(int quantity, HashSize size) Derives a hasher that produces a fixed quantity of distinct hash codes within a specified range.
default Hasher<T>	ints() Derives a hasher that produces an endless stream of hash values in the range HashSize.INT_SIZE generated from a single hash value created by this hasher.
default Hasher<T>	longs() Derives a hasher that produces an endless stream of hash values in the range HashSize.LONG_SIZE generated from a single hash value created by this hasher.
default Hasher<T>	sized(HashSize newSize) Derives a new hasher that generates hash codes within a different (generally smaller) range.

Methods inherited from interface com.tomgibara.hashing.Hashing

bigHashValue, booleansHasher, bytesHasher, bytesHashValue, charsHasher, digest, digest, digest, doublesHasher, floatsHasher, getQuantity, getSize, hash, identityHasher, intDerivedHasher, intHashValue, intsHasher, longHashValue, longsHasher, MD5, murmur3Int, murmur3Int, objectHasher, prng, prng, prng, SHA_1, SHA_256, shortsHasher

Method Detail

sized

default Hasher<T> sized(HashSize newSize)

Derives a new hasher that generates hash codes within a different (generally smaller) range. Unless the new size divides the size of this hasher, there is no guarantee that values will be evenly distributed over new range. At present, no attempt is made to distribute the hash values evenly over a larger range.

Parameters:

newSize - specifies a size for the derived hasher

Returns:

a hasher that redistributes hash values within the specified range

distinct

default Hasher<T> distinct(int quantity,
                           HashSize size)
                    throws IllegalArgumentException

Derives a hasher that produces a fixed quantity of distinct hash codes within a specified range. To ensure that all value combinations are possible, the size of this hasher must meet or exceed 'size choose quantity'.

Parameters:

quantity - the number of hash values derived from a single hash code of this hasher

size - the range over which distinct values will be generated

Returns:

a hasher that generates multiple distinct hash values

Throws:

IllegalArgumentException - if the size is not integer sized or the quantity is outside the range [1,size]

ints

default Hasher<T> ints()

Derives a hasher that produces an endless stream of hash values in the range HashSize.INT_SIZE generated from a single hash value created by this hasher. It is recommended that any hasher used to derive values in this way should have a size which is at least HashSize.INT_SIZE.

Returns:

a hasher that derives an endless stream of hash values for each object hashed by this hasher.

longs

default Hasher<T> longs()

Derives a hasher that produces an endless stream of hash values in the range HashSize.LONG_SIZE generated from a single hash value created by this hasher. It is recommended that any hasher used to derive values in this way should have a size which is at least HashSize.LONG_SIZE.

Returns:

a hasher that derives an endless stream of hash values for each object hashed by this hasher.