Package org.apache.lucene.index
Class AutomatonTermsEnum
java.lang.Object
org.apache.lucene.index.TermsEnum
org.apache.lucene.index.FilteredTermsEnum
org.apache.lucene.index.AutomatonTermsEnum
- All Implemented Interfaces:
BytesRefIterator
A FilteredTermsEnum that enumerates terms based upon what is accepted by a DFA.
The algorithm is such:
- As long as matches are successful, keep reading sequentially.
- When a match fails, skip to the next string in lexicographic order that does not enter a reject state.
The algorithm does not attempt to actually skip to the next string that is completely accepted. This is not possible when the language accepted by the FSM is not finite (i.e. * operator).
- NOTE: This API is for internal purposes only 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.index.FilteredTermsEnum
FilteredTermsEnum.AcceptStatusNested classes/interfaces inherited from class org.apache.lucene.index.TermsEnum
TermsEnum.SeekStatus -
Field Summary
Fields inherited from class org.apache.lucene.index.FilteredTermsEnum
actualTerm, tenum -
Constructor Summary
ConstructorsConstructorDescriptionAutomatonTermsEnum(TermsEnum tenum, CompiledAutomaton compiled) Construct an enumerator based upon an automaton, enumerating the specified field, working on a supplied TermsEnum -
Method Summary
Modifier and TypeMethodDescriptionprotected FilteredTermsEnum.AcceptStatusReturns true if the term matches the automaton.protected BytesRefnextSeekTerm(BytesRef term) On the first call toFilteredTermsEnum.next()or ifFilteredTermsEnum.accept(org.apache.lucene.util.BytesRef)returnsFilteredTermsEnum.AcceptStatus.YES_AND_SEEKorFilteredTermsEnum.AcceptStatus.NO_AND_SEEK, this method will be called to eventually seek the underlying TermsEnum to a new position.Methods inherited from class org.apache.lucene.index.FilteredTermsEnum
attributes, docFreq, impacts, next, ord, postings, prepareSeekExact, seekCeil, seekExact, seekExact, seekExact, setInitialSeekTerm, term, termState, totalTermFreq
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Constructor Details
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AutomatonTermsEnum
Construct an enumerator based upon an automaton, enumerating the specified field, working on a supplied TermsEnum- Parameters:
compiled- CompiledAutomaton- WARNING: This API is experimental and might change in incompatible ways in the next release.
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Method Details
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accept
Returns true if the term matches the automaton. Also stashes away the term to assist with smart enumeration.- Specified by:
acceptin classFilteredTermsEnum
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nextSeekTerm
Description copied from class:FilteredTermsEnumOn the first call toFilteredTermsEnum.next()or ifFilteredTermsEnum.accept(org.apache.lucene.util.BytesRef)returnsFilteredTermsEnum.AcceptStatus.YES_AND_SEEKorFilteredTermsEnum.AcceptStatus.NO_AND_SEEK, this method will be called to eventually seek the underlying TermsEnum to a new position. On the first call,currentTermwill benull, later calls will provide the term the underlying enum is positioned at. This method returns per default only one time the initial seek term and thennull, so no repositioning is ever done.Override this method, if you want a more sophisticated TermsEnum, that repositions the iterator during enumeration. If this method always returns
nullthe enum is empty.Please note: This method should always provide a greater term than the last enumerated term, else the behaviour of this enum violates the contract for TermsEnums.
- Overrides:
nextSeekTermin classFilteredTermsEnum- Throws:
IOException
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