object MurmurHash3 extends MurmurHash3
An implementation of Austin Appleby's MurmurHash 3 algorithm
(MurmurHash3_x86_32). This object contains methods that hash
values of various types as well as means to construct Hashing
objects.
This algorithm is designed to generate well-distributed non-cryptographic hashes. It is designed to hash data in 32 bit chunks (ints).
The mix method needs to be called at each step to update the intermediate hash value. For the last chunk to incorporate into the hash mixLast may be used instead, which is slightly faster. Finally finalizeHash needs to be called to compute the final hash value.
This is based on the earlier MurmurHash3 code by Rex Kerr, but the MurmurHash3 algorithm was since changed by its creator Austin Appleby to remedy some weaknesses and improve performance. This represents the latest and supposedly final version of the algorithm (revision 136).
- Source
- MurmurHash3.scala
- See also
- Alphabetic
- By Inheritance
- MurmurHash3
- MurmurHash3
- AnyRef
- Any
- Hide All
- Show All
- Public
- All
Type Members
- class ArrayHashing[T] extends Hashing[Array[T]]
Value Members
-
final
def
!=(arg0: Any): Boolean
Test two objects for inequality.
Test two objects for inequality.
- returns
trueif !(this == that), false otherwise.
- Definition Classes
- AnyRef → Any
-
final
def
##(): Int
Equivalent to
x.hashCodeexcept for boxed numeric types andnull.Equivalent to
x.hashCodeexcept for boxed numeric types andnull. For numerics, it returns a hash value which is consistent with value equality: if two value type instances compare as true, then ## will produce the same hash value for each of them. Fornullreturns a hashcode wherenull.hashCodethrows aNullPointerException.- returns
a hash value consistent with ==
- Definition Classes
- AnyRef → Any
-
final
def
==(arg0: Any): Boolean
The expression
x == thatis equivalent toif (x eq null) that eq null else x.equals(that).The expression
x == thatis equivalent toif (x eq null) that eq null else x.equals(that).- returns
trueif the receiver object is equivalent to the argument;falseotherwise.
- Definition Classes
- AnyRef → Any
- def arrayHash[T](a: Array[T]): Int
-
final
def
arrayHash[T](a: Array[T], seed: Int): Int
Compute the hash of an array.
Compute the hash of an array.
- Definition Classes
- MurmurHash3
- def arrayHashing[T]: ArrayHashing[T]
- final val arraySeed: Int(1007110753)
-
final
def
asInstanceOf[T0]: T0
Cast the receiver object to be of type
T0.Cast the receiver object to be of type
T0.Note that the success of a cast at runtime is modulo Scala's erasure semantics. Therefore the expression
1.asInstanceOf[String]will throw aClassCastExceptionat runtime, while the expressionList(1).asInstanceOf[List[String]]will not. In the latter example, because the type argument is erased as part of compilation it is not possible to check whether the contents of the list are of the requested type.- returns
the receiver object.
- Definition Classes
- Any
- Exceptions thrown
ClassCastExceptionif the receiver object is not an instance of the erasure of typeT0.
- def bytesHash(data: Array[Byte]): Int
-
final
def
bytesHash(data: Array[Byte], seed: Int): Int
Compute the hash of a byte array.
Compute the hash of a byte array. Faster than arrayHash, because it hashes 4 bytes at once.
- Definition Classes
- MurmurHash3
- def bytesHashing: Hashing[Array[Byte]]
-
def
clone(): AnyRef
Create a copy of the receiver object.
-
final
def
eq(arg0: AnyRef): Boolean
Tests whether the argument (
that) is a reference to the receiver object (this).Tests whether the argument (
that) is a reference to the receiver object (this).The
eqmethod implements an equivalence relation on non-null instances ofAnyRef, and has three additional properties:- It is consistent: for any non-null instances
xandyof typeAnyRef, multiple invocations ofx.eq(y)consistently returnstrueor consistently returnsfalse. - For any non-null instance
xof typeAnyRef,x.eq(null)andnull.eq(x)returnsfalse. null.eq(null)returnstrue.
When overriding the
equalsorhashCodemethods, it is important to ensure that their behavior is consistent with reference equality. Therefore, if two objects are references to each other (o1 eq o2), they should be equal to each other (o1 == o2) and they should hash to the same value (o1.hashCode == o2.hashCode).- returns
trueif the argument is a reference to the receiver object;falseotherwise.
- Definition Classes
- AnyRef
- It is consistent: for any non-null instances
-
def
equals(arg0: Any): Boolean
The equality method for reference types.
-
def
finalize(): Unit
Called by the garbage collector on the receiver object when there are no more references to the object.
Called by the garbage collector on the receiver object when there are no more references to the object.
The details of when and if the
finalizemethod is invoked, as well as the interaction betweenfinalizeand non-local returns and exceptions, are all platform dependent. -
final
def
finalizeHash(hash: Int, length: Int): Int
Finalize a hash to incorporate the length and make sure all bits avalanche.
Finalize a hash to incorporate the length and make sure all bits avalanche.
- Definition Classes
- MurmurHash3
-
final
def
getClass(): Class[_]
Returns the runtime class representation of the object.
-
def
hashCode(): Int
The hashCode method for reference types.
-
final
def
isInstanceOf[T0]: Boolean
Test whether the dynamic type of the receiver object is
T0.Test whether the dynamic type of the receiver object is
T0.Note that the result of the test is modulo Scala's erasure semantics. Therefore the expression
1.isInstanceOf[String]will returnfalse, while the expressionList(1).isInstanceOf[List[String]]will returntrue. In the latter example, because the type argument is erased as part of compilation it is not possible to check whether the contents of the list are of the specified type.- returns
trueif the receiver object is an instance of erasure of typeT0;falseotherwise.
- Definition Classes
- Any
-
final
def
listHash(xs: collection.immutable.List[_], seed: Int): Int
- Definition Classes
- MurmurHash3
- def mapHash(xs: Map[_, _]): Int
- final val mapSeed: Int
-
final
def
mix(hash: Int, data: Int): Int
Mix in a block of data into an intermediate hash value.
Mix in a block of data into an intermediate hash value.
- Definition Classes
- MurmurHash3
-
final
def
mixLast(hash: Int, data: Int): Int
May optionally be used as the last mixing step.
May optionally be used as the last mixing step. Is a little bit faster than mix, as it does no further mixing of the resulting hash. For the last element this is not necessary as the hash is thoroughly mixed during finalization anyway.
- Definition Classes
- MurmurHash3
-
final
def
ne(arg0: AnyRef): Boolean
Equivalent to
!(this eq that).Equivalent to
!(this eq that).- returns
trueif the argument is not a reference to the receiver object;falseotherwise.
- Definition Classes
- AnyRef
-
final
def
notify(): Unit
Wakes up a single thread that is waiting on the receiver object's monitor.
Wakes up a single thread that is waiting on the receiver object's monitor.
- Definition Classes
- AnyRef
- Annotations
- @native()
- Note
not specified by SLS as a member of AnyRef
-
final
def
notifyAll(): Unit
Wakes up all threads that are waiting on the receiver object's monitor.
Wakes up all threads that are waiting on the receiver object's monitor.
- Definition Classes
- AnyRef
- Annotations
- @native()
- Note
not specified by SLS as a member of AnyRef
- def orderedHash(xs: TraversableOnce[Any]): Int
-
final
def
orderedHash(xs: TraversableOnce[Any], seed: Int): Int
Compute a hash that depends on the order of its arguments.
Compute a hash that depends on the order of its arguments.
- Definition Classes
- MurmurHash3
- def orderedHashing: Hashing[TraversableOnce[Any]]
- def productHash(x: Product): Int
-
final
def
productHash(x: Product, seed: Int): Int
Compute the hash of a product
Compute the hash of a product
- Definition Classes
- MurmurHash3
- def productHashing: Hashing[Product]
- final val productSeed: Int(-889275714)
-
def
seqHash(xs: collection.Seq[_]): Int
To offer some potential for optimization.
- final val seqSeed: Int
- def setHash(xs: Set[_]): Int
- final val setSeed: Int
- def stringHash(x: String): Int
-
final
def
stringHash(str: String, seed: Int): Int
Compute the hash of a string
Compute the hash of a string
- Definition Classes
- MurmurHash3
- def stringHashing: Hashing[String]
- final val stringSeed: Int(-137723950)
- final val symmetricSeed: Int(-1248659538)
-
final
def
synchronized[T0](arg0: ⇒ T0): T0
- Definition Classes
- AnyRef
-
def
toString(): String
Creates a String representation of this object.
Creates a String representation of this object. The default representation is platform dependent. On the java platform it is the concatenation of the class name, "@", and the object's hashcode in hexadecimal.
- returns
a String representation of the object.
- Definition Classes
- AnyRef → Any
- final val traversableSeed: Int(-415593707)
- def unorderedHash(xs: TraversableOnce[Any]): Int
-
final
def
unorderedHash(xs: TraversableOnce[Any], seed: Int): Int
Compute a hash that is symmetric in its arguments - that is a hash where the order of appearance of elements does not matter.
Compute a hash that is symmetric in its arguments - that is a hash where the order of appearance of elements does not matter. This is useful for hashing sets, for example.
- Definition Classes
- MurmurHash3
- def unorderedHashing: Hashing[TraversableOnce[Any]]
-
final
def
wait(): Unit
- Definition Classes
- AnyRef
- Annotations
- @throws( ... )
-
final
def
wait(arg0: Long, arg1: Int): Unit
- Definition Classes
- AnyRef
- Annotations
- @throws( ... )
- final def wait(arg0: Long): Unit
This is the documentation for the Scala standard library.
Package structure
The scala package contains core types like
Int,Float,ArrayorOptionwhich are accessible in all Scala compilation units without explicit qualification or imports.Notable packages include:
scala.collectionand its sub-packages contain Scala's collections frameworkscala.collection.immutable- Immutable, sequential data-structures such asVector,List,Range,HashMaporHashSetscala.collection.mutable- Mutable, sequential data-structures such asArrayBuffer,StringBuilder,HashMaporHashSetscala.collection.concurrent- Mutable, concurrent data-structures such asTrieMapscala.collection.parallel.immutable- Immutable, parallel data-structures such asParVector,ParRange,ParHashMaporParHashSetscala.collection.parallel.mutable- Mutable, parallel data-structures such asParArray,ParHashMap,ParTrieMaporParHashSetscala.concurrent- Primitives for concurrent programming such asFuturesandPromisesscala.io- Input and output operationsscala.math- Basic math functions and additional numeric types likeBigIntandBigDecimalscala.sys- Interaction with other processes and the operating systemscala.util.matching- Regular expressionsOther packages exist. See the complete list on the right.
Additional parts of the standard library are shipped as separate libraries. These include:
scala.reflect- Scala's reflection API (scala-reflect.jar)scala.xml- XML parsing, manipulation, and serialization (scala-xml.jar)scala.swing- A convenient wrapper around Java's GUI framework called Swing (scala-swing.jar)scala.util.parsing- Parser combinators (scala-parser-combinators.jar)Automatic imports
Identifiers in the scala package and the
scala.Predefobject are always in scope by default.Some of these identifiers are type aliases provided as shortcuts to commonly used classes. For example,
Listis an alias forscala.collection.immutable.List.Other aliases refer to classes provided by the underlying platform. For example, on the JVM,
Stringis an alias forjava.lang.String.