Package org.apache.lucene.index

Class TermsEnum

    • Field Detail

      • EMPTY

        public static final TermsEnum EMPTY
        An empty TermsEnum for quickly returning an empty instance e.g. in MultiTermQuery

        Please note: This enum should be unmodifiable, but it is currently possible to add Attributes to it. This should not be a problem, as the enum is always empty and the existence of unused Attributes does not matter.

    • Constructor Detail

      • TermsEnum

        protected TermsEnum()
        Sole constructor. (For invocation by subclass constructors, typically implicit.)

    • Method Detail

      • attributes

        public AttributeSource attributes()
        Returns the related attributes.

      • seekCeil

        public abstract TermsEnum.SeekStatus seekCeil​(BytesRef text)
                                       throws IOException
        Seeks to the specified term, if it exists, or to the next (ceiling) term. Returns SeekStatus to indicate whether exact term was found, a different term was found, or EOF was hit. The target term may be before or after the current term. If this returns SeekStatus.END, the enum is unpositioned.
        Throws:
        IOException

      • seekExact

        public abstract void seekExact​(long ord)
                        throws IOException
        Seeks to the specified term by ordinal (position) as previously returned by ord(). The target ord may be before or after the current ord, and must be within bounds.
        Throws:
        IOException

      • seekExact

        public void seekExact​(BytesRef term,
                      TermState state)
               throws IOException
        Expert: Seeks a specific position by TermState previously obtained from termState(). Callers should maintain the TermState to use this method. Low-level implementations may position the TermsEnum without re-seeking the term dictionary.

        Seeking by TermState should only be used iff the state was obtained from the same TermsEnum instance.

        NOTE: Using this method with an incompatible TermState might leave this TermsEnum in undefined state. On a segment level TermState instances are compatible only iff the source and the target TermsEnum operate on the same field. If operating on segment level, TermState instances must not be used across segments.

        NOTE: A seek by TermState might not restore the AttributeSource's state. AttributeSource states must be maintained separately if this method is used.

        Parameters:
        term - the term the TermState corresponds to
        state - the TermState
        Throws:
        IOException

      • totalTermFreq

        public abstract long totalTermFreq()
                            throws IOException
        Returns the total number of occurrences of this term across all documents (the sum of the freq() for each doc that has this term). This will be -1 if the codec doesn't support this measure. Note that, like other term measures, this measure does not take deleted documents into account.
        Throws:
        IOException

      • docs

        public final DocsEnum docs​(Bits liveDocs,
                           DocsEnum reuse)
                    throws IOException
        Get DocsEnum for the current term. Do not call this when the enum is unpositioned. This method will not return null.
        Parameters:
        liveDocs - unset bits are documents that should not be returned
        reuse - pass a prior DocsEnum for possible reuse
        Throws:
        IOException

      • docs

        public abstract DocsEnum docs​(Bits liveDocs,
                              DocsEnum reuse,
                              int flags)
                       throws IOException
        Get DocsEnum for the current term, with control over whether freqs are required. Do not call this when the enum is unpositioned. This method will not return null.
        Parameters:
        liveDocs - unset bits are documents that should not be returned
        reuse - pass a prior DocsEnum for possible reuse
        flags - specifies which optional per-document values you require; see DocsEnum.FLAG_FREQS
        Throws:
        IOException
        See Also:
        docs(Bits, DocsEnum, int)

      • docsAndPositions

        public abstract DocsAndPositionsEnum docsAndPositions​(Bits liveDocs,
                                                      DocsAndPositionsEnum reuse,
                                                      int flags)
                                               throws IOException
        Get DocsAndPositionsEnum for the current term, with control over whether offsets and payloads are required. Some codecs may be able to optimize their implementation when offsets and/or payloads are not required. Do not call this when the enum is unpositioned. This will return null if positions were not indexed.
        Parameters:
        liveDocs - unset bits are documents that should not be returned
        reuse - pass a prior DocsAndPositionsEnum for possible reuse
        flags - specifies which optional per-position values you require; see DocsAndPositionsEnum.FLAG_OFFSETS and DocsAndPositionsEnum.FLAG_PAYLOADS.
        Throws:
        IOException