Class VLLcpMonotoneMinimalPerfectHashFunction<T>

java.lang.Object
it.unimi.dsi.fastutil.objects.AbstractObject2LongFunction<T>
it.unimi.dsi.sux4j.mph.AbstractHashFunction<T>
it.unimi.dsi.sux4j.mph.VLLcpMonotoneMinimalPerfectHashFunction<T>
All Implemented Interfaces:
it.unimi.dsi.fastutil.Function<T,Long>, it.unimi.dsi.fastutil.objects.Object2LongFunction<T>, it.unimi.dsi.fastutil.Size64, Serializable, Function<T,Long>, ToLongFunction<T>
public class VLLcpMonotoneMinimalPerfectHashFunction<T> extends AbstractHashFunction<T> implements Serializable, it.unimi.dsi.fastutil.Size64
A monotone minimal perfect hash implementation based on fixed-size bucketing that uses longest common prefixes as distributors, and store their lengths using a GOVMinimalPerfectHashFunction indexing an EliasFanoLongBigList. In theory, this function should use less memory than an LcpMonotoneMinimalPerfectHashFunction when the lengths of common prefixes vary wildly, but in practice a TwoStepsLcpMonotoneMinimalPerfectHashFunction is often a better choice.
See Also:

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    protected final int
    bucketSize
    The size of a bucket.
    protected final int
    bucketSizeMask
    The mask for log2BucketSize bits.
    protected final GOV3Function<it.unimi.dsi.bits.BitVector>
    lcp2Bucket
    A function mapping each longest common prefix to its bucket.
    protected final EliasFanoLongBigList
    lcpLengths
    A list, indexed by mph, containing for each element the length of the longest common prefix of its bucket.
    protected final int
    log2BucketSize
    Fast.ceilLog2(int) of bucketSize.
    protected final GOVMinimalPerfectHashFunction<it.unimi.dsi.bits.BitVector>
    mph
    A function mapping each element to a distinct index.
    protected final long
    n
    The number of elements.
    protected final it.unimi.dsi.fastutil.longs.LongBigList
    offsets
    A list, indexed by mph, containing the offset of each element inside its bucket.
    static final long
    serialVersionUID
     
    protected final it.unimi.dsi.bits.TransformationStrategy<? super T>
    transform
    The transformation strategy.

    Fields inherited from class it.unimi.dsi.fastutil.objects.AbstractObject2LongFunction

    defRetValue

  • Constructor Summary

    Constructors
    Constructor
    Description
    VLLcpMonotoneMinimalPerfectHashFunction(Iterable<? extends T> iterable, int numElements, it.unimi.dsi.bits.TransformationStrategy<? super T> transform)
     
    VLLcpMonotoneMinimalPerfectHashFunction(Iterable<? extends T> iterable, it.unimi.dsi.bits.TransformationStrategy<? super T> transform)
     

  • Method Summary

    Modifier and Type
    Method
    Description
    long
    getLong(Object o)
     
    static void
    main(String[] arg)
     
    long
    numBits()
    Returns the number of bits used by this structure.
    long
    size64()
     

    Methods inherited from class AbstractHashFunction

    containsKey, size

    Methods inherited from class it.unimi.dsi.fastutil.objects.AbstractObject2LongFunction

    defaultReturnValue, defaultReturnValue

    Methods inherited from class Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

    Methods inherited from interface it.unimi.dsi.fastutil.Function

    apply, clear

    Methods inherited from interface Function

    compose

    Methods inherited from interface it.unimi.dsi.fastutil.objects.Object2LongFunction

    andThen, andThenByte, andThenChar, andThenDouble, andThenFloat, andThenInt, andThenLong, andThenObject, andThenReference, andThenShort, applyAsLong, composeByte, composeChar, composeDouble, composeFloat, composeInt, composeLong, composeObject, composeReference, composeShort, get, getOrDefault, getOrDefault, put, put, remove, removeLong

    Methods inherited from interface it.unimi.dsi.fastutil.Size64

    size

  • Field Details

    • serialVersionUID

      public static final long serialVersionUID
      See Also:

    • n

      protected final long n
      The number of elements.

    • bucketSize

      protected final int bucketSize
      The size of a bucket.

    • log2BucketSize

      protected final int log2BucketSize
      Fast.ceilLog2(int) of bucketSize.

    • bucketSizeMask

      protected final int bucketSizeMask
      The mask for log2BucketSize bits.

    • mph

      protected final GOVMinimalPerfectHashFunction<it.unimi.dsi.bits.BitVector> mph
      A function mapping each element to a distinct index.

    • offsets

      protected final it.unimi.dsi.fastutil.longs.LongBigList offsets
      A list, indexed by mph, containing the offset of each element inside its bucket.

    • lcpLengths

      protected final EliasFanoLongBigList lcpLengths
      A list, indexed by mph, containing for each element the length of the longest common prefix of its bucket.

    • lcp2Bucket

      protected final GOV3Function<it.unimi.dsi.bits.BitVector> lcp2Bucket
      A function mapping each longest common prefix to its bucket.

    • transform

      protected final it.unimi.dsi.bits.TransformationStrategy<? super T> transform
      The transformation strategy.

  • Constructor Details

    • VLLcpMonotoneMinimalPerfectHashFunction

      public VLLcpMonotoneMinimalPerfectHashFunction(Iterable<? extends T> iterable, it.unimi.dsi.bits.TransformationStrategy<? super T> transform) throws IOException
      Throws:
      IOException

    • VLLcpMonotoneMinimalPerfectHashFunction

      public VLLcpMonotoneMinimalPerfectHashFunction(Iterable<? extends T> iterable, int numElements, it.unimi.dsi.bits.TransformationStrategy<? super T> transform) throws IOException
      Throws:
      IOException

  • Method Details

    • getLong

      public long getLong(Object o)
      Specified by:
      getLong in interface it.unimi.dsi.fastutil.objects.Object2LongFunction<T>

    • size64

      public long size64()
      Specified by:
      size64 in interface it.unimi.dsi.fastutil.Size64
      Overrides:
      size64 in class AbstractHashFunction<T>

    • numBits

      public long numBits()
      Returns the number of bits used by this structure.
      Returns:
      the number of bits used by this structure.

    • main

      public static void main(String[] arg) throws NoSuchMethodException, IOException, com.martiansoftware.jsap.JSAPException
      Throws:
      NoSuchMethodException
      IOException
      com.martiansoftware.jsap.JSAPException