Interface DocumentIterator

    • Field Detail

      • END_OF_LIST

        static final long END_OF_LIST
        A special value denoting that the end of the list has been reached.
        See Also:
        Constant Field Values
    • Method Detail

      • intervalIterator

        IntervalIterator intervalIterator()
                                   throws IOException
        Returns the interval iterator of this document iterator for single-index queries.

        This is a commodity method that can be used only for queries built over a single index.

        Returns:
        an interval iterator.
        Throws:
        IllegalStateException - if this document iterator is not built on a single index.
        IOException
        See Also:
        intervalIterator(Index)
      • intervalIterator

        IntervalIterator intervalIterator​(Index index)
                                   throws IOException
        Returns the interval iterator of this document iterator for the given index.

        After a call to nextDocument(), this iterator can be used to retrieve the intervals in the current document (the one returned by nextDocument()) for the index index.

        Note that if all indices have positions, it is guaranteed that at least one index will return an interval. However, for disjunctive queries it cannot be guaranteed that all indices will return an interval.

        Indices without positions always return IntervalIterators.TRUE. Thus, in presence of indices without positions it is possible that no intervals at all are available.

        Parameters:
        index - an index (must be one over which the query was built).
        Returns:
        an interval iterator over the current document in index.
        Throws:
        IOException
      • indices

        ReferenceSet<Index> indices()
        Returns the set of indices over which this iterator is built.
        Returns:
        the set of indices over which this iterator is built.
      • nextDocument

        long nextDocument()
                   throws IOException
        Returns the next document provided by this document iterator, or END_OF_LIST if no more documents are available.
        Returns:
        the next document, or END_OF_LIST if no more documents are available.
        Throws:
        IOException
      • mayHaveNext

        boolean mayHaveNext()
        Returns whether there may be a next document, possibly with false positives.
        Returns:
        true there may be a next document; false if certainly there is no next document.
      • document

        long document()
        Returns the last document returned by nextDocument().
        Returns:
        the last document returned by nextDocument(), -1 if no document has been returned yet, and END_OF_LIST if the list of results has been exhausted.
      • skipTo

        long skipTo​(long n)
             throws IOException
        Skips all documents smaller than n.

        Define the current document k associated with this document iterator as follows:

        If k is larger than or equal to n, then this method does nothing and returns k. Otherwise, a call to this method is equivalent to

         while( ( k = nextDocument() ) < n );
         return k;
         

        Thus, when a result kEND_OF_LIST is returned, the state of this iterator will be exactly the same as after a call to nextDocument() that returned k. In particular, the first document larger than or equal to n (when returned by this method) will not be returned by the next call to nextDocument().

        Parameters:
        n - a document pointer.
        Returns:
        a document pointer larger than or equal to n if available, END_OF_LIST otherwise.
        Throws:
        IOException
      • accept

        <T> T accept​(DocumentIteratorVisitor<T> visitor)
              throws IOException
        Accepts a visitor.

        A document iterator is usually structured as composite, with operators as internal nodes and IndexIterators as leaves. This method implements the visitor pattern.

        Parameters:
        visitor - the visitor.
        Returns:
        an object resulting from the visit, or null if the visit was interrupted.
        Throws:
        IOException
      • acceptOnTruePaths

        <T> T acceptOnTruePaths​(DocumentIteratorVisitor<T> visitor)
                         throws IOException
        Accepts a visitor after a call to nextDocument(), limiting recursion to true paths.

        After a call to nextDocument(), a document iterator is positioned over a document. This call is equivalent to accept(DocumentIteratorVisitor), but visits only along true paths.

        We define a true path as a path from the root of the composite that passes only through nodes whose associated subtree is positioned on the same document of the root. Note that OrDocumentIterators detach exhausted iterators from the composite tree, so true paths define the subtree that is causing the current document to satisfy the query represented by this document iterator.

        For more elaboration, and the main application of this method, see CounterCollectionVisitor.

        Parameters:
        visitor - the visitor.
        Returns:
        an object resulting from the visit, or null if the visit was interrupted.
        Throws:
        IOException
        See Also:
        accept(DocumentIteratorVisitor), CounterCollectionVisitor
      • weight

        double weight()
        Returns the weight associated with this iterator.

        The number returned by this method has no fixed semantics: different scorers might choose different interpretations, or even ignore it.

        Returns:
        the weight associated with this iterator.
      • weight

        DocumentIterator weight​(double weight)
        Sets the weight of this index iterator.
        Parameters:
        weight - the weight of this index iterator.
        Returns:
        this document iterator.
      • dispose

        void dispose()
              throws IOException
        Disposes this document iterator, releasing all resources.

        This method should propagate down to the underlying index iterators, where it should release resources such as open files and network connections. If you're doing your own resource tracking and pooling, then you do not need to call this method.

        Throws:
        IOException