core/Lucy/Index/Posting.cfh

/* Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

parcel Lucy;

/** Vessel holding statistical data for a posting.
 *
 * A Posting, in Apache Lucy, is a vessel which stores information about a
 * term-document match.  (See L<Lucy::Docs::IRTheory> for the
 * academic definition of "posting".)
 *
 * Subclasses include
 * L<MatchPosting|Lucy::Index::Posting::MatchPosting>, the simplest
 * posting format, and
 * L<ScorePosting|Lucy::Index::Posting::ScorePosting>, the default.
 */
class Lucy::Index::Posting cnick Post inherits Lucy::Util::Stepper {

    int32_t doc_id;

    public inert Posting*
    init(Posting *self);

    /** Create a RawPosting object, suitable for index-time sorting.
     *
     * Updates the state of the document id, but nothing else.
     */
    abstract incremented RawPosting*
    Read_Raw(Posting *self, InStream *instream, int32_t last_doc_id,
             CharBuf *term_text, MemoryPool *mem_pool);

    /** Process an Inversion into RawPosting objects and add them all to the
     * supplied PostingPool.
     */
    abstract void
    Add_Inversion_To_Pool(Posting *self, PostingPool *post_pool,
                          Inversion *inversion, FieldType *type,
                          int32_t doc_id, float doc_boost,
                          float length_norm);

    public void
    Set_Doc_ID(Posting *self, int32_t doc_id);

    public int32_t
    Get_Doc_ID(Posting *self);

    /** Factory method for creating a Matcher.
     */
    abstract incremented Matcher*
    Make_Matcher(Posting *self, Similarity *sim, PostingList *plist,
                 Compiler *compiler, bool_t need_score);
}

abstract class Lucy::Index::Posting::PostingWriter cnick PostWriter
    inherits Lucy::Index::DataWriter {

    int32_t field_num;

    inert PostingWriter*
    init(PostingWriter *self, Schema *schema, Snapshot *snapshot,
         Segment *segment, PolyReader *polyreader, int32_t field_num);

    /** Take a RawPosting that was flattened earlier and write it to the
     * index. */
    abstract void
    Write_Posting(PostingWriter *self, RawPosting *posting);

    /** Start a new term.  Update the TermInfo to reflect the state of the
     * PostingWriter.
     */
    abstract void
    Start_Term(PostingWriter *self, TermInfo *tinfo);

    /** Update the TermInfo to reflect the internal state of the
     * PostingWriter so that skip information can be written.
     *
     * TODO: This is an ugly hack which needs refactoring.
     */
    abstract void
    Update_Skip_Info(PostingWriter *self, TermInfo *tinfo);
}