org.apache.lucene.search.suggest
Class Lookup

java.lang.Object
  org.apache.lucene.search.suggest.Lookup

Direct Known Subclasses:

FSTCompletionLookup, FSTLookup, JaspellLookup, TSTLookup, WFSTCompletionLookup

public abstract class Lookup
extends Object

Simple Lookup interface for CharSequence suggestions.

WARNING: This API is experimental and might change in incompatible ways in the next release.

Nested Class Summary

static class	Lookup.LookupPriorityQueue A PriorityQueue collecting a fixed size of high priority Lookup.LookupResult
static class	Lookup.LookupResult Result of a lookup.

Field Summary

static Comparator<CharSequence>

CHARSEQUENCE_COMPARATOR A simple char-by-char comparator for CharSequence

Constructor Summary

Lookup()

Method Summary

void	build(Dictionary dict) Build lookup from a dictionary.
abstract void	build(TermFreqIterator tfit) Builds up a new internal Lookup representation based on the given TermFreqIterator.
abstract boolean	load(InputStream input) Discard current lookup data and load it from a previously saved copy.
abstract List<Lookup.LookupResult>	lookup(CharSequence key, boolean onlyMorePopular, int num) Look up a key and return possible completion for this key.
abstract boolean	store(OutputStream output) Persist the constructed lookup data to a directory.

Methods inherited from class java.lang.Object

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

Field Detail

CHARSEQUENCE_COMPARATOR

public static final Comparator<CharSequence> CHARSEQUENCE_COMPARATOR

A simple char-by-char comparator for CharSequence

Constructor Detail

Lookup

public Lookup()

Method Detail

build

public void build(Dictionary dict)
           throws IOException

Build lookup from a dictionary. Some implementations may require sorted or unsorted keys from the dictionary's iterator - use SortedTermFreqIteratorWrapper or UnsortedTermFreqIteratorWrapper in such case.

Throws:

IOException

build

public abstract void build(TermFreqIterator tfit)
                    throws IOException

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

Throws:

IOException

lookup

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

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

Parameters:

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

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)

store

public abstract boolean store(OutputStream output)
                       throws IOException

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

Parameters:

output - OutputStream to write the data to.

Returns:

true if successful, false if unsuccessful or not supported.

Throws:

IOException - when fatal IO error occurs.

load

public abstract boolean load(InputStream input)
                      throws IOException

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

Parameters:

input - the InputStream to load the lookup data.

Returns:

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

Throws:

IOException - when fatal IO error occurs.