org.terrier.structures

Class MapLexicon

java.lang.Object

org.terrier.structures.Lexicon<String>

org.terrier.structures.MapLexicon

All Implemented Interfaces:

Closeable, AutoCloseable, Iterable<Map.Entry<String,LexiconEntry>>

Direct Known Subclasses:

FSOMapFileLexicon, MemoryLexicon

public abstract class MapLexicon
extends Lexicon<String>
implements Closeable

Implementation of a lexicon. This class should be subclassed by any lexicon implementation which use a java.util.Map for storing entries.

Since:

3.0

Author:

Craig Macdonald

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
protected static interface	MapLexicon.Id2EntryIndexLookup Interface for getting the lexicon term index for a given term id
protected static class	MapLexicon.IdIsIndex Lexicon map where the termid is the term index

Field Summary

Fields

Modifier and Type	Field and Description
protected WriteableFactory<org.apache.hadoop.io.Text>	keyFactory
protected Map<org.apache.hadoop.io.Text,LexiconEntry>	map
protected Object	modificationLock

Constructor Summary

Constructors

Constructor and Description
MapLexicon(Map<org.apache.hadoop.io.Text,LexiconEntry> backingMap) Construct an instance of the class with
MapLexicon(Map<org.apache.hadoop.io.Text,LexiconEntry> backingMap, MapLexicon.Id2EntryIndexLookup idlookupobject) Construct an instance of the class with

Method Summary

Methods

Modifier and Type	Method and Description
void	close()
Map.Entry<String,LexiconEntry>	getIthLexiconEntry(int index) Get the term and LexiconEntry (contains statistics and a pointer) for the entry in the lexicon with the specified index.
Map.Entry<String,LexiconEntry>	getLexiconEntry(int termid) Get the term and LexiconEntry (contains statistics and a pointer) for a given term id.
LexiconEntry	getLexiconEntry(String term) Get the LexiconEntry (contains statistics and a pointer) for the given term.
Iterator<Map.Entry<String,LexiconEntry>>	getLexiconEntryRange(String from, String to) Returns an iterator over a set of LexiconEntries within a range of entries in the lexicon.
int	numberOfEntries() Return the number of entries in the lexicon
protected void	setTermIdLookup(MapLexicon.Id2EntryIndexLookup idlookupobject)

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.lang.Iterable

iterator

Field Detail

keyFactory

protected WriteableFactory<org.apache.hadoop.io.Text> keyFactory

modificationLock

protected Object modificationLock

map

protected final Map<org.apache.hadoop.io.Text,LexiconEntry> map

Constructor Detail

MapLexicon

public MapLexicon(Map<org.apache.hadoop.io.Text,LexiconEntry> backingMap)

Construct an instance of the class with

Parameters:

backingMap -

MapLexicon

public MapLexicon(Map<org.apache.hadoop.io.Text,LexiconEntry> backingMap,
          MapLexicon.Id2EntryIndexLookup idlookupobject)

Construct an instance of the class with

Parameters:

backingMap -

idlookupobject -

Method Detail

setTermIdLookup

protected void setTermIdLookup(MapLexicon.Id2EntryIndexLookup idlookupobject)

getLexiconEntry

public LexiconEntry getLexiconEntry(String term)

Get the LexiconEntry (contains statistics and a pointer) for the given term. Returns null if the term is not found in the lexicon.

Specified by:

getLexiconEntry in class Lexicon<String>

Parameters:

term - key to lookup the lexicon with

Returns:

LexiconEntry for that term, or null if not found

getIthLexiconEntry

public Map.Entry<String,LexiconEntry> getIthLexiconEntry(int index)

Get the term and LexiconEntry (contains statistics and a pointer) for the entry in the lexicon with the specified index. Throws NoSuchElementException is the termid is not found.

Specified by:

getIthLexiconEntry in class Lexicon<String>

Parameters:

index - the entry number to lookup in the lexicon

Returns:

Map.Entry tuple containing the term and the LexiconEntry

getLexiconEntryRange

public Iterator<Map.Entry<String,LexiconEntry>> getLexiconEntryRange(String from,
                                                            String to)

Returns an iterator over a set of LexiconEntries within a range of entries in the lexicon.

Specified by:

getLexiconEntryRange in class Lexicon<String>

Parameters:

from - low endpoint term in the subset, inclusive.

to - high endpoint term in the subset, exclusive.

Returns:

Iterator over the set.

getLexiconEntry

public Map.Entry<String,LexiconEntry> getLexiconEntry(int termid)

Get the term and LexiconEntry (contains statistics and a pointer) for a given term id. Throws NoSuchElementException is the termid is not found.

Specified by:

getLexiconEntry in class Lexicon<String>

Parameters:

termid - the term id to lookup in the lexicon

Returns:

Map.Entry tuple containing the term and the LexiconEntry

numberOfEntries

public int numberOfEntries()

Return the number of entries in the lexicon

Specified by:

numberOfEntries in class Lexicon<String>

close

public void close()
           throws IOException

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

Throws:

IOException