/* NiuTrans.Tensor - an open-source tensor library
 * Copyright (C) 2019, Natural Language Processing Lab, Northestern University.
 * All rights reserved.
 *
 * Licensed 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.
 */

/*
 * $Created by: XIAO Tong (xiaotong@mail.neu.edu.cn) 2019-03-27
 */

#ifndef __T2TSEARCH_H__
#define __T2TSEARCH_H__

#include "T2TModel.h"
#include "T2TPredictor.h"

namespace transformer
{

/* The class orgnizes the search process. It calls predictors to generate 
   distributions of the predictions and prunes the search space by beam pruning.
   It results in a graph where each path respresents a translation hypothsis.
   The output can be the path with the highest model score. */
class T2TSearch
{
public:
    /* max length of the generated sequence */
    int maxLength;

public:
    /* constructor */
    T2TSearch() {};

    /* de-constructor */
    ~T2TSearch() {};

    /* search for the most promising states */
    void Search(T2TModel * model, XTensor * input, XTensor * output);

    /* beam pruning */
    void Prune(T2TStateBundle * beam);

    /* save the output sequences in a tensor */
    void DumpOutput(T2TStateBundle * beam, XTensor * output);
};

}

#endif