/* 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;

/** Match a set of document ids.
 *
 * A Matcher iterates over a set of ascending document ids.  Some Matchers
 * implement Score() and can assign relevance scores to the docs that they
 * match.  Other implementations may be match-only.
 */

abstract class Lucy::Search::Matcher inherits Lucy::Object::Obj {

    /** Abstract constructor.
     */
    public inert Matcher*
    init(Matcher* self);

    /** Proceed to the next doc id.
     *
     * @return A positive doc id, or 0 once the iterator is exhausted.
     */
    public abstract int32_t
    Next(Matcher *self);

    /** Advance the iterator to the first doc id greater than or equal to
     * <code>target</code>. The default implementation simply calls Next()
     * over and over, but subclasses have the option of doing something more
     * efficient.
     *
     * @param target A positive doc id, which must be greater than the current
     * doc id once the iterator has been initialized.
     * @return A positive doc id, or 0 once the iterator is exhausted.
     */
    public int32_t
    Advance(Matcher *self, int32_t target);

    /** Return the current doc id.  Valid only after a successful call to
     * Next() or Advance() and must not be called otherwise.
     */
    public abstract int32_t
    Get_Doc_ID(Matcher *self);

    /** Return the score of the current document.
     *
     * Only Matchers which are used for scored search need implement Score().
     */
    public abstract float
    Score(Matcher *self);

    /** Collect hits.
     *
     * @param collector The Collector to collect hits with.
     * @param deletions A deletions iterator.
     */
    void
    Collect(Matcher *self, Collector *collector,
            Matcher *deletions = NULL);
}