io.h

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/*
 * 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.
 */
 
#ifndef MXNET_CPP_IO_H_
#define MXNET_CPP_IO_H_
 
#include <map>
#include <string>
#include <vector>
#include <sstream>
#include "mxnet-cpp/base.h"
#include "mxnet-cpp/ndarray.h"
#include "dmlc/logging.h"
 
namespace mxnet {
namespace cpp {
class DataBatch {
 public:
  NDArray data;
  NDArray label;
  int pad_num;
  std::vector<int> index;
};
class DataIter {
 public:
  virtual void BeforeFirst(void)          = 0;
  virtual bool Next(void)                 = 0;
  virtual NDArray GetData(void)           = 0;
  virtual NDArray GetLabel(void)          = 0;
  virtual int GetPadNum(void)             = 0;
  virtual std::vector<int> GetIndex(void) = 0;
 
  DataBatch GetDataBatch() {
    return DataBatch{GetData(), GetLabel(), GetPadNum(), GetIndex()};
  }
  void Reset() {
    BeforeFirst();
  }
 
  virtual ~DataIter() = default;
};
 
class MXDataIterMap {
 public:
  inline MXDataIterMap() {
    mx_uint num_data_iter_creators      = 0;
    DataIterCreator* data_iter_creators = nullptr;
    int r = MXListDataIters(&num_data_iter_creators, &data_iter_creators);
    CHECK_EQ(r, 0);
    for (mx_uint i = 0; i < num_data_iter_creators; i++) {
      const char* name;
      const char* description;
      mx_uint num_args;
      const char** arg_names;
      const char** arg_type_infos;
      const char** arg_descriptions;
      r = MXDataIterGetIterInfo(data_iter_creators[i],
                                &name,
                                &description,
                                &num_args,
                                &arg_names,
                                &arg_type_infos,
                                &arg_descriptions);
      CHECK_EQ(r, 0);
      mxdataiter_creators_[name] = data_iter_creators[i];
    }
  }
  inline DataIterCreator GetMXDataIterCreator(const std::string& name) {
    return mxdataiter_creators_[name];
  }
 
 private:
  std::map<std::string, DataIterCreator> mxdataiter_creators_;
};
 
struct MXDataIterBlob {
 public:
  MXDataIterBlob() : handle_(nullptr) {}
  explicit MXDataIterBlob(DataIterHandle handle) : handle_(handle) {}
  ~MXDataIterBlob() {
    MXDataIterFree(handle_);
  }
  DataIterHandle handle_;
 
 private:
  MXDataIterBlob& operator=(const MXDataIterBlob&);
};
 
class MXDataIter : public DataIter {
 public:
  explicit MXDataIter(const std::string& mxdataiter_type);
  MXDataIter(const MXDataIter& other) {
    creator_  = other.creator_;
    params_   = other.params_;
    blob_ptr_ = other.blob_ptr_;
  }
  void BeforeFirst();
  bool Next();
  NDArray GetData();
  NDArray GetLabel();
  int GetPadNum();
  std::vector<int> GetIndex();
  MXDataIter CreateDataIter();
  template <typename T>
  MXDataIter& SetParam(const std::string& name, const T& value) {
    std::string value_str;
    std::stringstream ss;
    ss << value;
    ss >> value_str;
 
    params_[name] = value_str;
    return *this;
  }
 
 private:
  DataIterCreator creator_;
  std::map<std::string, std::string> params_;
  std::shared_ptr<MXDataIterBlob> blob_ptr_;
  static MXDataIterMap*& mxdataiter_map();
};
}  // namespace cpp
}  // namespace mxnet
 
#endif  // MXNET_CPP_IO_H_