/*******************************************************************************
 * Copyright (c) 2015-2018 Skymind, Inc.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Apache License, Version 2.0 which is available at
 * https://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.
 *
 * SPDX-License-Identifier: Apache-2.0
 ******************************************************************************/

package org.deeplearning4j.iterator;

import org.nd4j.linalg.primitives.Pair;

import java.util.List;

/**
 *
 * LabeledSentenceProvider: a simple iterator interface over sentences/documents that have a label.<br>
 *
 * This is intended for use with {@link CnnSentenceDataSetIterator}
 *
 * @author Alex Black
 */
public interface LabeledSentenceProvider {

    /**
     * Are there more sentences/documents available?
     */
    boolean hasNext();

    /**
     *
     * @return Pair: sentence/document text and label
     */
    Pair<String, String> nextSentence();

    /**
     * Reset the iterator - including shuffling the order, if necessary/appropriate
     */
    void reset();

    /**
     * Return the total number of sentences, or -1 if not available
     */
    int totalNumSentences();

    /**
     * Return the list of labels - this also defines the class/integer label assignment order
     */
    List<String> allLabels();

    /**
     * Equivalent to allLabels().size()
     */
    int numLabelClasses();

}
