NAME

       Lucy::Index::IndexReader - Read from an inverted index.

SYNOPSIS

           my $reader = Lucy::Index::IndexReader->open(
               index => '/path/to/index',
           );
           my $seg_readers = $reader->seg_readers;
           for my $seg_reader (@$seg_readers) {
               my $seg_name = $seg_reader->get_segment->get_name;
               my $num_docs = $seg_reader->doc_max;
               print "Segment $seg_name ($num_docs documents):\n";
               my $doc_reader = $seg_reader->obtain("Lucy::Index::DocReader");
               for my $doc_id ( 1 .. $num_docs ) {
                   my $doc = $doc_reader->fetch_doc($doc_id);
                   print "  $doc_id: $doc->{title}\n";
               }
           }

DESCRIPTION

       IndexReader is the interface through which IndexSearcher objects access the content of an
       index.

       IndexReader objects always represent a point-in-time view of an index as it existed at the
       moment the reader was created.  If you want search results to reflect modifications to an
       index, you must create a new IndexReader after the update process completes.

       IndexReaders are composites; most of the work is done by individual DataReader sub-
       components, which may be accessed via fetch() and obtain().  The most efficient and
       powerful access to index data happens at the segment level via SegReader's sub-components.

CONSTRUCTORS

   open( [labeled params] )
           my $reader = Lucy::Index::IndexReader->open(
               index    => '/path/to/index', # required
               snapshot => $snapshot,
               manager  => $index_manager,
           );

       IndexReader is an abstract base class; open() returns the IndexReader subclass PolyReader,
       which channels the output of 0 or more SegReaders.

       •   index - Either a string filepath or a Folder.

       •   snapshot - A Snapshot.  If not supplied, the most recent snapshot file will be used.

       •   manager - An IndexManager.  Read-locking is off by default; supplying this argument
           turns it on.

ABSTRACT METHODS

   doc_max()
       Return the maximum number of documents available to the reader, which is also the highest
       possible internal document id.  Documents which have been marked as deleted but not yet
       purged from the index are included in this count.

   doc_count()
       Return the number of documents available to the reader, subtracting any that are marked as
       deleted.

   del_count()
       Return the number of documents which have been marked as deleted but not yet purged from
       the index.

   seg_readers()
       Return an array of all the SegReaders represented within the IndexReader.

   offsets()
       Return an array with one entry for each segment, corresponding to segment doc_id start
       offset.

METHODS

   fetch(api)
       Fetch a component, or return undef if the component can't be found.

       •   api - The name of the DataReader subclass that the desired component must implement.

   obtain(api)
       Fetch a component, or throw an error if the component can't be found.

       •   api - The name of the DataReader subclass that the desired component must implement.

INHERITANCE

       Lucy::Index::IndexReader isa Lucy::Index::DataReader isa Lucy::Object::Obj.