/* 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;

/** Term-Document pairings.
 *
 * PostingList is an iterator which supplies a list of document ids that match
 * a given term.
 *
 * See L<Lucy::Docs::IRTheory> for definitions of "posting" and "posting
 * list".
 */
class Lucy::Index::PostingList cnick PList
    inherits Lucy::Search::Matcher {

    public inert PostingList*
    init(PostingList *self);

    /** Return the iterator's current Posting.  Should not be called before
     * the iterator is initialized or after it empties.
     */
    abstract Posting*
    Get_Posting(PostingList *self);

    /** Return the number of documents that the PostingList contains.  (This
     * number will include any documents which have been marked as deleted but
     * not yet purged.)
     */
    public abstract uint32_t
    Get_Doc_Freq(PostingList *self);

    /** Prepare the PostingList object to iterate over matches for documents
     * that match <code>target</code>.
     *
     * @param target The term to match.  If NULL, the iterator will be empty.
     */
    public abstract void
    Seek(PostingList *self, Obj *target = NULL);

    abstract void
    Seek_Lex(PostingList *self, Lexicon *lexicon);

    /** Invoke Post_Make_Matcher() for this PostingList's posting.
     */
    abstract Matcher*
    Make_Matcher(PostingList *self, Similarity *similarity,
                 Compiler *compiler, bool_t need_score);

    /** Indexing helper function.
     */
    abstract RawPosting*
    Read_Raw(PostingList *self, int32_t last_doc_id, CharBuf *term_text,
             MemoryPool *mem_pool);
}