Package it.unimi.dsi.big.util

Class SemiExternalGammaBigList

java.lang.Object

java.util.AbstractCollection<Long>

it.unimi.dsi.fastutil.longs.AbstractLongCollection

it.unimi.dsi.fastutil.longs.AbstractLongBigList

it.unimi.dsi.big.util.SemiExternalGammaBigList

All Implemented Interfaces:

BigList<Long>, LongBigList, LongCollection, LongIterable, LongStack, Size64, Stack<Long>, Comparable<BigList<? extends Long>>, Iterable<Long>, Collection<Long>

public class SemiExternalGammaBigList
extends AbstractLongBigList

Provides semi-external random access to a big list of γ-encoded integers.

This class is a semi-external LongBigList that MG4J uses to access files containing frequencies.

Instead, this class accesses frequencies in their compressed forms, and provides entry points for random access to each long. At construction time, entry points are computed with a certain step, which is the number of longs accessible from each entry point, or, equivalently, the maximum number of longs that will be necessary to read to access a given long.

Warning: This class is not thread safe, and needs to be synchronised to be used in a multithreaded environment.

Since:

2.0

Author:

Fabien Campagne, Sebastiano Vigna

Nested Class Summary

Nested classes/interfaces inherited from class it.unimi.dsi.fastutil.longs.AbstractLongBigList

AbstractLongBigList.LongRandomAccessSubList, AbstractLongBigList.LongSubList

Field Summary

Fields

Modifier and Type	Field	Description
static final int	DEFAULT_STEP

Constructor Summary

Constructors

Constructor	Description
SemiExternalGammaBigList(InputBitStream longs)	Creates a new semi-external list.
SemiExternalGammaBigList(InputBitStream longs, int step, long numLongs)	Creates a new semi-external list.

Method Summary

Modifier and Type	Method	Description
final long	getLong(long index)
long	size64()

Methods inherited from class it.unimi.dsi.fastutil.longs.AbstractLongBigList

add, add, add, addAll, addAll, addAll, addAll, addElements, addElements, clear, compareTo, contains, ensureIndex, ensureRestrictedIndex, equals, forEach, get, getElements, hashCode, indexOf, indexOf, iterator, lastIndexOf, lastIndexOf, listIterator, listIterator, peek, peekLong, pop, popLong, push, push, rem, remove, removeElements, removeLong, set, set, setElements, size, size, subList, top, topLong, toString

Methods inherited from class it.unimi.dsi.fastutil.longs.AbstractLongCollection

add, contains, containsAll, containsAll, forEach, remove, removeAll, removeAll, removeIf, retainAll, retainAll, toArray, toLongArray, toLongArray

Methods inherited from class java.util.AbstractCollection

isEmpty, toArray, toArray

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface java.util.Collection

containsAll, isEmpty, removeAll, retainAll, toArray, toArray, toArray

Methods inherited from interface it.unimi.dsi.fastutil.longs.LongBigList

addAll, addAll, addAll, addAll, getElements, setElements, setElements, spliterator

Methods inherited from interface it.unimi.dsi.fastutil.longs.LongCollection

add, contains, containsAll, longIterator, longParallelStream, longSpliterator, longStream, parallelStream, remove, removeAll, removeIf, removeIf, removeIf, retainAll, stream, toArray, toLongArray, toLongArray

Methods inherited from interface it.unimi.dsi.fastutil.longs.LongIterable

forEach, forEach

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

isEmpty

Field Details

DEFAULT_STEP

public static final int DEFAULT_STEP

See Also:

• Constant Field Values

Constructor Details

SemiExternalGammaBigList

public SemiExternalGammaBigList(InputBitStream longs,
 int step,
 long numLongs)
                         throws IOException

Creates a new semi-external list.

Parameters:

longs - a bit stream containing γ-encoded longs.

step - the step used to build random-access entry points, or -1 to get DEFAULT_STEP; note that a step causing more than 2³¹ slots will be silently increased.

numLongs - the overall number of offsets (i.e., the number of terms).

Throws:

IOException

SemiExternalGammaBigList

public SemiExternalGammaBigList(InputBitStream longs)
                         throws IOException

Creates a new semi-external list.

This quick-and-dirty constructor estimates the number of longs by checking for an EOFException.

Parameters:

longs - a bit stream containing γ-encoded longs.

Throws:

IOException

Method Details

getLong

public final long getLong(long index)

size64

public long size64()