JBoss Parent POM 1.7.0.Final · org.wildfly.common.math.HashMath

Modifier and Type	Field and Description
private static final int	PRESELECTED_PRIME

Access	Constructor and Description
private	HashMath()

Method Summary

Modifier and Type	Method and Description
public static int	Returns: the new accumulated hash code multiHashOrdered(int the accumulated hash code of the previous stage accumulatedHash, int a prime multiplier prime, int the hash code of the next single item nextHash) A hash function which combines an accumulated hash with a next hash such that `f(f(k, p2, b), p1, a) ≠ₙ f(f(k, p1, a), p2, b)`.
public static int	Returns: the new accumulated hash code multiHashOrdered(int the accumulated hash code of the previous stage accumulatedHash, int the hash code of the next single item nextHash) A hash function which combines an accumulated hash with a next hash such that `f(f(k, b), a) ≠ₙ f(f(k, a), b)`.
public static int	Returns: the new accumulated hash code multiHashUnordered(int the accumulated hash code of the previous stage accumulatedHash, int a prime multiplier prime, int the hash code of the next single item nextHash) A hash function which combines an accumulated hash with a next hash such that `f(f(k, p2, b), p1, a) = f(f(k, p1, a), p2, b)`.
public static int	Returns: the new accumulated hash code multiHashUnordered(int the accumulated hash code of the previous stage accumulatedHash, int the hash code of the next single item nextHash) A hash function which combines an accumulated hash with a next hash such that `f(f(k, b), a) = f(f(k, a), b)`.
public static int	Returns: the wrapped multiply result multiplyWrap(int the first number to multiply a, int the second number to multiply b) Multiply two unsigned integers together.
public static int	Returns: the rounded power of two value roundToPowerOfTwo(int the value (must not be negative and must be less than or equal to `2^31`) value) Round the given value up to the next positive power of two.

Inherited from java.lang.Object:: clone equals finalize getClass hashCode notify notifyAll toString wait wait wait

PRESELECTED_PRIME	back to summary
private static final int PRESELECTED_PRIME

HashMath	back to summary
private HashMath()

Method Detail

multiHashOrdered back to summary

multiHashOrdered	back to summary
public static int multiHashOrdered(int accumulatedHash, int prime, int nextHash) A hash function which combines an accumulated hash with a next hash such that `f(f(k, p2, b), p1, a) ≠ₙ f(f(k, p1, a), p2, b)`. This function is suitable for object chains whose order affects the overall equality of the hash code. The exact algorithm is not specified and is therefore subject to change and should not be relied upon for hash codes that persist outside of the JVM process. Parameters accumulatedHash:int the accumulated hash code of the previous stage prime:int a prime multiplier nextHash:int the hash code of the next single item Returns:int the new accumulated hash code

public static int multiHashOrdered(int accumulatedHash, int prime, int nextHash)

A hash function which combines an accumulated hash with a next hash such that f(f(k, p2, b), p1, a) ≠ₙ f(f(k, p1, a), p2, b). This function is suitable for object chains whose order affects the overall equality of the hash code.

The exact algorithm is not specified and is therefore subject to change and should not be relied upon for hash codes that persist outside of the JVM process.

Parameters

accumulatedHash:int: the accumulated hash code of the previous stage
prime:int: a prime multiplier
nextHash:int: the hash code of the next single item

Returns:int

the new accumulated hash code

multiHashOrdered back to summary

multiHashOrdered	back to summary
public static int multiHashOrdered(int accumulatedHash, int nextHash) A hash function which combines an accumulated hash with a next hash such that `f(f(k, b), a) ≠ₙ f(f(k, a), b)`. This function is suitable for object chains whose order affects the overall equality of the hash code. The exact algorithm is not specified and is therefore subject to change and should not be relied upon for hash codes that persist outside of the JVM process. Parameters accumulatedHash:int the accumulated hash code of the previous stage nextHash:int the hash code of the next single item Returns:int the new accumulated hash code

public static int multiHashOrdered(int accumulatedHash, int nextHash)

A hash function which combines an accumulated hash with a next hash such that f(f(k, b), a) ≠ₙ f(f(k, a), b). This function is suitable for object chains whose order affects the overall equality of the hash code.

The exact algorithm is not specified and is therefore subject to change and should not be relied upon for hash codes that persist outside of the JVM process.

Parameters

accumulatedHash:int: the accumulated hash code of the previous stage
nextHash:int: the hash code of the next single item

Returns:int

the new accumulated hash code

multiHashUnordered back to summary

multiHashUnordered	back to summary
public static int multiHashUnordered(int accumulatedHash, int prime, int nextHash) A hash function which combines an accumulated hash with a next hash such that `f(f(k, p2, b), p1, a) = f(f(k, p1, a), p2, b)`. This function is suitable for object chains whose order does not affect the overall equality of the hash code. The exact algorithm is not specified and is therefore subject to change and should not be relied upon for hash codes that persist outside of the JVM process. Parameters accumulatedHash:int the accumulated hash code of the previous stage prime:int a prime multiplier nextHash:int the hash code of the next single item Returns:int the new accumulated hash code

public static int multiHashUnordered(int accumulatedHash, int prime, int nextHash)

A hash function which combines an accumulated hash with a next hash such that f(f(k, p2, b), p1, a) = f(f(k, p1, a), p2, b). This function is suitable for object chains whose order does not affect the overall equality of the hash code.

The exact algorithm is not specified and is therefore subject to change and should not be relied upon for hash codes that persist outside of the JVM process.

Parameters

accumulatedHash:int: the accumulated hash code of the previous stage
prime:int: a prime multiplier
nextHash:int: the hash code of the next single item

Returns:int

the new accumulated hash code

multiHashUnordered back to summary

multiHashUnordered	back to summary
public static int multiHashUnordered(int accumulatedHash, int nextHash) A hash function which combines an accumulated hash with a next hash such that `f(f(k, b), a) = f(f(k, a), b)`. This function is suitable for object chains whose order does not affect the overall equality of the hash code. The exact algorithm is not specified and is therefore subject to change and should not be relied upon for hash codes that persist outside of the JVM process. Parameters accumulatedHash:int the accumulated hash code of the previous stage nextHash:int the hash code of the next single item Returns:int the new accumulated hash code

public static int multiHashUnordered(int accumulatedHash, int nextHash)

A hash function which combines an accumulated hash with a next hash such that f(f(k, b), a) = f(f(k, a), b). This function is suitable for object chains whose order does not affect the overall equality of the hash code.

The exact algorithm is not specified and is therefore subject to change and should not be relied upon for hash codes that persist outside of the JVM process.

Parameters

accumulatedHash:int: the accumulated hash code of the previous stage
nextHash:int: the hash code of the next single item

Returns:int

the new accumulated hash code

multiplyWrap back to summary

multiplyWrap	back to summary
public static int multiplyWrap(int a, int b) Multiply two unsigned integers together. If the result overflows a 32-bit number, XOR the overflowed bits back into the result. This operation is commutative, i.e. if we designate the `⨰` symbol to represent this operation, then `a ⨰ b = b ⨰ a`. This operation is not associative, i.e. `(a ⨰ b) ⨰ c ≠ₙ a ⨰ (b ⨰ c)` (the symbol `≠ₙ` meaning "not necessarily equal to"), therefore this operation is suitable for ordered combinatorial hash functions. Parameters a:int the first number to multiply b:int the second number to multiply Returns:int the wrapped multiply result

public static int multiplyWrap(int a, int b)

Multiply two unsigned integers together. If the result overflows a 32-bit number, XOR the overflowed bits back into the result. This operation is commutative, i.e. if we designate the ⨰ symbol to represent this operation, then a ⨰ b = b ⨰ a. This operation is not associative, i.e. (a ⨰ b) ⨰ c ≠ₙ a ⨰ (b ⨰ c) (the symbol ≠ₙ meaning "not necessarily equal to"), therefore this operation is suitable for ordered combinatorial hash functions.

Parameters

a:int: the first number to multiply
b:int: the second number to multiply

Returns:int

the wrapped multiply result

roundToPowerOfTwo back to summary

roundToPowerOfTwo	back to summary
public static int roundToPowerOfTwo(int value) Round the given value up to the next positive power of two. Parameters value:int the value (must not be negative and must be less than or equal to `2^31`) Returns:int the rounded power of two value

public static int roundToPowerOfTwo(int value)

Round the given value up to the next positive power of two.

Parameters

value:int: the value (must not be negative and must be less than or equal to 2^31)

Returns:int

the rounded power of two value

public final Class HashMath

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