Module org.apache.lucene.suggest

Package org.apache.lucene.search.suggest.tst

Class TSTLookup

java.lang.Object

org.apache.lucene.search.suggest.Lookup

org.apache.lucene.search.suggest.tst.TSTLookup

All Implemented Interfaces:

Accountable

public class TSTLookup
extends Lookup

Suggest implementation based on a Ternary Search Tree

See Also:

• TSTAutocomplete

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.lucene.search.suggest.Lookup

Lookup.LookupPriorityQueue, Lookup.LookupResult

Field Summary

Fields

Modifier and Type	Field	Description
(package private) TSTAutocomplete	autocomplete
private long	count	Number of entries the lookup was built with
private static final byte	EQ_KID
private static final byte	HAS_TOKEN
private static final byte	HAS_VALUE
private static final byte	HI_KID
private static final byte	LO_KID
(package private) TernaryTreeNode	root
private final Directory	tempDir
private final String	tempFileNamePrefix
private static final Comparator<BytesRef>	utf8SortedAsUTF16SortOrder	TST uses UTF-16 sorting, so we need a suitable BytesRef comparator to do this.

Fields inherited from class org.apache.lucene.search.suggest.Lookup

CHARSEQUENCE_COMPARATOR

Fields inherited from interface org.apache.lucene.util.Accountable

NULL_ACCOUNTABLE

Constructor Summary

Constructors

Constructor	Description
TSTLookup()	Creates a new TSTLookup with an empty Ternary Search Tree.
TSTLookup(Directory tempDir, String tempFileNamePrefix)	Creates a new TSTLookup, for building.

Method Summary

Modifier and Type	Method	Description
boolean	add(CharSequence key, Object value)	Adds a new node if key already exists, otherwise replaces its value.
void	build(InputIterator iterator)	Builds up a new internal Lookup representation based on the given InputIterator.
private static boolean	charSeqEquals(CharSequence left, CharSequence right)
Object	get(CharSequence key)	Returns the value for the specified key, or null if the key does not exist.
long	getCount()	Get the number of entries the lookup was built with
boolean	load(DataInput input)	Discard current lookup data and load it from a previously saved copy.
List<Lookup.LookupResult>	lookup(CharSequence key, Set<BytesRef> contexts, boolean onlyMorePopular, int num)	Look up a key and return possible completion for this key.
long	ramBytesUsed()	Returns byte size of the underlying TST
private void	readRecursively(DataInput in, TernaryTreeNode node)
boolean	store(DataOutput output)	Persist the constructed lookup data to a directory.
private void	writeRecursively(DataOutput out, TernaryTreeNode node)

Methods inherited from class org.apache.lucene.search.suggest.Lookup

build, load, lookup, lookup, store

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.lucene.util.Accountable

getChildResources

Field Details

root

TernaryTreeNode root

autocomplete

TSTAutocomplete autocomplete

count

private long count

Number of entries the lookup was built with

tempDir

private final Directory tempDir

tempFileNamePrefix

private final String tempFileNamePrefix

utf8SortedAsUTF16SortOrder

private static final Comparator<BytesRef> utf8SortedAsUTF16SortOrder

TST uses UTF-16 sorting, so we need a suitable BytesRef comparator to do this.

LO_KID

private static final byte LO_KID

See Also:

• Constant Field Values

EQ_KID

private static final byte EQ_KID

See Also:

• Constant Field Values

HI_KID

private static final byte HI_KID

See Also:

• Constant Field Values

HAS_TOKEN

private static final byte HAS_TOKEN

See Also:

• Constant Field Values

HAS_VALUE

private static final byte HAS_VALUE

See Also:

• Constant Field Values

Constructor Details

TSTLookup

public TSTLookup()

Creates a new TSTLookup with an empty Ternary Search Tree.

See Also:

• build(InputIterator)

TSTLookup

public TSTLookup(Directory tempDir,
 String tempFileNamePrefix)

Creates a new TSTLookup, for building.

See Also:

• build(InputIterator)

Method Details

build

public void build(InputIterator iterator)
           throws IOException

Description copied from class: Lookup

Builds up a new internal Lookup representation based on the given InputIterator. The implementation might re-sort the data internally.

Specified by:

build in class Lookup

Throws:

IOException

add

public boolean add(CharSequence key,
 Object value)

Adds a new node if key already exists, otherwise replaces its value.

This method always returns true.

get

public Object get(CharSequence key)

Returns the value for the specified key, or null if the key does not exist.

charSeqEquals

private static boolean charSeqEquals(CharSequence left,
 CharSequence right)

lookup

public List<Lookup.LookupResult> lookup(CharSequence key,
 Set<BytesRef> contexts,
 boolean onlyMorePopular,
 int num)

Description copied from class: Lookup

Look up a key and return possible completion for this key.

Specified by:

lookup in class Lookup

Parameters:

key - lookup key. Depending on the implementation this may be a prefix, misspelling, or even infix.

contexts - contexts to filter the lookup by, or null if all contexts are allowed; if the suggestion contains any of the contexts, it's a match

onlyMorePopular - return only more popular results

num - maximum number of results to return

Returns:

a list of possible completions, with their relative weight (e.g. popularity)

readRecursively

private void readRecursively(DataInput in,
 TernaryTreeNode node)
                      throws IOException

Throws:

IOException

writeRecursively

private void writeRecursively(DataOutput out,
 TernaryTreeNode node)
                       throws IOException

Throws:

IOException

store

public boolean store(DataOutput output)
              throws IOException

Description copied from class: Lookup

Persist the constructed lookup data to a directory. Optional operation.

Specified by:

store in class Lookup

Parameters:

output - DataOutput to write the data to.

Returns:

true if successful, false if unsuccessful or not supported.

Throws:

IOException - when fatal IO error occurs.

load

public boolean load(DataInput input)
             throws IOException

Description copied from class: Lookup

Discard current lookup data and load it from a previously saved copy. Optional operation.

Specified by:

load in class Lookup

Parameters:

input - the DataInput to load the lookup data.

Returns:

true if completed successfully, false if unsuccessful or not supported.

Throws:

IOException - when fatal IO error occurs.

ramBytesUsed

public long ramBytesUsed()

Returns byte size of the underlying TST

getCount

public long getCount()

Description copied from class: Lookup

Get the number of entries the lookup was built with

Specified by:

getCount in class Lookup

Returns:

total number of suggester entries