Class FSTCompletion
java.lang.Object
org.apache.lucene.search.suggest.fst.FSTCompletion
Finite state automata based implementation of "autocomplete" functionality.
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- WARNING: This API is experimental and might change in incompatible ways in the next release.
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Nested Class Summary
Nested ClassesModifier and TypeClassDescriptionstatic final classA single completion for a given key. -
Field Summary
Fields -
Constructor Summary
ConstructorsConstructorDescriptionFSTCompletion(FST<Object> automaton) Defaults to higher weights first and exact first.FSTCompletion(FST<Object> automaton, boolean higherWeightsFirst, boolean exactFirst) Constructs an FSTCompletion, specifying higherWeightsFirst and exactFirst. -
Method Summary
Modifier and TypeMethodDescriptionintgetBucket(CharSequence key) Returns the bucket assigned to a given key (if found) or-1if no exact match exists.intReturns the bucket count (discretization thresholds).getFST()Returns the internal automaton.lookup(CharSequence key) Lookup suggestions tokeyand return a stream of matching completions.lookup(CharSequence key, int num) Lookup suggestions tokey.
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Field Details
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DEFAULT_BUCKETS
public static final int DEFAULT_BUCKETSDefault number of buckets.- See Also:
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Constructor Details
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FSTCompletion
Constructs an FSTCompletion, specifying higherWeightsFirst and exactFirst.- Parameters:
automaton- Automaton with completions. SeeFSTCompletionBuilder.higherWeightsFirst- Return most popular suggestions first. This is the default behavior for this implementation. Setting it tofalsehas no effect (use constant term weights to sort alphabetically only).exactFirst- Find and push an exact match to the first position of the result list if found.
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FSTCompletion
Defaults to higher weights first and exact first.- See Also:
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Method Details
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lookup
Lookup suggestions tokey.- Parameters:
key- The prefix to which suggestions should be sought.num- At most this number of suggestions will be returned.- Returns:
- Returns the suggestions, sorted by their approximated weight first (decreasing) and then alphabetically (UTF-8 codepoint order).
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lookup
Lookup suggestions tokeyand return a stream of matching completions. The stream fetches completions dynamically - it can be filtered and limited to acquire the desired number of completions without collecting all of them.- Parameters:
key- The prefix to which suggestions should be sought.- Returns:
- Returns the suggestions
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getBucketCount
public int getBucketCount()Returns the bucket count (discretization thresholds). -
getBucket
Returns the bucket assigned to a given key (if found) or-1if no exact match exists. -
getFST
Returns the internal automaton.
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