Package it.unimi.dsi.util

Class SemiExternalGammaList

java.lang.Object

java.util.AbstractCollection<Long>

it.unimi.dsi.fastutil.longs.AbstractLongCollection

it.unimi.dsi.fastutil.longs.AbstractLongList

it.unimi.dsi.util.SemiExternalGammaList

All Implemented Interfaces:

LongCollection, LongIterable, LongList, LongStack, Stack<Long>, Comparable<List<? extends Long>>, Iterable<Long>, Collection<Long>, List<Long>

public class SemiExternalGammaList
extends AbstractLongList

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

This class is a semi-external LongList 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.

Author:

Fabien Campagne, Sebastiano Vigna

Nested Class Summary

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

AbstractLongList.LongRandomAccessSubList, AbstractLongList.LongSubList

Field Summary

Fields

Modifier and Type	Field	Description
static final int	DEFAULT_STEP

Constructor Summary

Constructors

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

Method Summary

Modifier and Type	Method	Description
final long	getLong(int index)
int	size()

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

add, add, addAll, addAll, addAll, addAll, addElements, addElements, clear, compareTo, contains, ensureIndex, ensureRestrictedIndex, equals, forEach, getElements, hashCode, indexOf, iterator, lastIndexOf, listIterator, listIterator, peekLong, popLong, push, rem, removeElements, removeLong, replaceAll, set, setElements, size, subList, toArray, toLongArray, topLong, toString

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

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

toArray

Methods inherited from interface java.util.List

containsAll, isEmpty, removeAll, retainAll, toArray, toArray

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

containsAll, longIterator, longParallelStream, longSpliterator, longStream, parallelStream, removeAll, removeIf, removeIf, removeIf, retainAll, spliterator, stream, toLongArray

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

forEach, forEach

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

add, add, addAll, addAll, contains, get, indexOf, lastIndexOf, remove, remove, replaceAll, replaceAll, set, setElements, setElements, sort, sort, spliterator, unstableSort, unstableSort

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

peek, pop, push, top

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

SemiExternalGammaList

public SemiExternalGammaList(InputBitStream longs,
 int step,
 int 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.

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

Throws:

IOException

SemiExternalGammaList

public SemiExternalGammaList(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(int index)

size

public int size()

Specified by:

size in interface Collection<Long>

Specified by:

size in interface List<Long>

Specified by:

size in class AbstractCollection<Long>