Class WFSTCompletionLookup
java.lang.Object
org.apache.lucene.search.suggest.Lookup
org.apache.lucene.search.suggest.fst.WFSTCompletionLookup
- All Implemented Interfaces:
Accountable
Suggester based on a weighted FST: it first traverses the prefix, then walks the n
shortest paths to retrieve top-ranked suggestions.
NOTE: Input weights must be between 0 and Integer.MAX_VALUE, any other values
will be rejected.
- WARNING: This API is experimental and might change in incompatible ways in the next release.
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Nested Class Summary
Nested classes/interfaces inherited from class org.apache.lucene.search.suggest.Lookup
Lookup.LookupPriorityQueue, Lookup.LookupResult -
Field Summary
Fields inherited from class org.apache.lucene.search.suggest.Lookup
CHARSEQUENCE_COMPARATORFields inherited from interface org.apache.lucene.util.Accountable
NULL_ACCOUNTABLE -
Constructor Summary
ConstructorsConstructorDescriptionWFSTCompletionLookup(Directory tempDir, String tempFileNamePrefix) WFSTCompletionLookup(Directory tempDir, String tempFileNamePrefix, boolean exactFirst) Creates a new suggester. -
Method Summary
Modifier and TypeMethodDescriptionvoidbuild(InputIterator iterator) Builds up a new internalLookuprepresentation based on the givenInputIterator.get(CharSequence key) Returns the weight associated with an input string, or null if it does not exist.longgetCount()Get the number of entries the lookup was built withbooleanDiscard current lookup data and load it from a previously saved copy.lookup(CharSequence key, Set<BytesRef> contexts, boolean onlyMorePopular, int num) Look up a key and return possible completion for this key.longReturns byte size of the underlying FST.booleanstore(DataOutput output) Persist the constructed lookup data to a directory.
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Constructor Details
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WFSTCompletionLookup
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WFSTCompletionLookup
Creates a new suggester.- Parameters:
exactFirst-trueif suggestions that match the prefix exactly should always be returned first, regardless of score. This has no performance impact, but could result in low-quality suggestions.
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Method Details
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build
Description copied from class:LookupBuilds up a new internalLookuprepresentation based on the givenInputIterator. The implementation might re-sort the data internally.- Specified by:
buildin classLookup- Throws:
IOException
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store
Description copied from class:LookupPersist the constructed lookup data to a directory. Optional operation.- Specified by:
storein classLookup- Parameters:
output-DataOutputto write the data to.- Returns:
- true if successful, false if unsuccessful or not supported.
- Throws:
IOException- when fatal IO error occurs.
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load
Description copied from class:LookupDiscard current lookup data and load it from a previously saved copy. Optional operation.- Specified by:
loadin classLookup- Parameters:
input- theDataInputto load the lookup data.- Returns:
- true if completed successfully, false if unsuccessful or not supported.
- Throws:
IOException- when fatal IO error occurs.
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lookup
public List<Lookup.LookupResult> lookup(CharSequence key, Set<BytesRef> contexts, boolean onlyMorePopular, int num) Description copied from class:LookupLook up a key and return possible completion for this key.- Specified by:
lookupin classLookup- 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 matchonlyMorePopular- return only more popular resultsnum- maximum number of results to return- Returns:
- a list of possible completions, with their relative weight (e.g. popularity)
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get
Returns the weight associated with an input string, or null if it does not exist. -
ramBytesUsed
public long ramBytesUsed()Returns byte size of the underlying FST. -
getChildResources
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getCount
public long getCount()Description copied from class:LookupGet the number of entries the lookup was built with
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