orc_field_writer.hpp

/*
 * Copyright (c) 2020, NVIDIA CORPORATION.
 *
 * 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.
 */
#pragma once

#include "orc.h"
#include <numeric>
#include <string>

/**
 * @file orc_field_writer.hpp
 * @brief Struct to encapsulate common functionality required to implement
 * `ProtobufWriter::write(...)` functions
 */

namespace cudf {
namespace io {
namespace orc {

struct ProtobufWriter::ProtobufFieldWriter {
  int struct_size;
  ProtobufWriter* p;

  ProtobufFieldWriter(ProtobufWriter* pbw) : struct_size(0), p(pbw) {}

  /**
   * @brief Function to write a unsigned integer to the internal buffer
   */
  template <typename T>
  void field_uint(int field, const T& value)
  {
    struct_size += p->put_uint(field * 8 + PB_TYPE_VARINT);
    struct_size += p->put_uint(static_cast<uint64_t>(value));
  }

  /**
   * @brief Function to write a vector of unsigned integers to the internal
   * buffer
   */
  template <typename T>
  void field_packed_uint(int field, const std::vector<T>& value)
  {
    struct_size += p->put_uint(field * 8 + PB_TYPE_FIXEDLEN);
    auto lpos = p->m_buf->size();
    p->put_byte(0);
    auto sz = std::accumulate(value.begin(), value.end(), 0, [p = this->p](size_t sum, auto val) {
      return sum + p->put_uint(val);
    });

    struct_size += sz + 1;
    for (; sz > 0x7f; sz >>= 7, struct_size++)
      p->m_buf->insert(p->m_buf->begin() + (lpos++), static_cast<uint8_t>((sz & 0x7f) | 0x80));
    (*(p->m_buf))[lpos] = static_cast<uint8_t>(sz);
  }

  /**
   * @brief Function to write a string to the internal buffer
   */
  void field_string(int field, const std::string& value)
  {
    size_t len = value.length();
    struct_size += p->put_uint(field * 8 + PB_TYPE_FIXEDLEN);
    struct_size += p->put_uint(len) + len;
    p->put_bytes(value);
  }

  /**
   * @brief Function to write a blob to the internal buffer
   */
  template <typename T>
  void field_blob(int field, const std::vector<T>& value)
  {
    size_t len = value.size();
    struct_size += p->put_uint(field * 8 + PB_TYPE_FIXEDLEN);
    struct_size += p->put_uint(len) + len;
    p->put_bytes(value);
  }

  /**
   * @brief Function to write a struct to the internal buffer
   */
  template <typename T>
  void field_struct(int field, const T& value)
  {
    struct_size += p->put_uint((field)*8 + PB_TYPE_FIXEDLEN);
    auto lpos = p->m_buf->size();
    p->put_byte(0);
    auto sz = p->write(value);
    struct_size += sz + 1;
    for (; sz > 0x7f; sz >>= 7, struct_size++)
      p->m_buf->insert(p->m_buf->begin() + (lpos++), static_cast<uint8_t>((sz & 0x7f) | 0x80));
    (*(p->m_buf))[lpos] = static_cast<uint8_t>(sz);
  }

  /**
   * @brief Function to write a vector of strings to the internal buffer
   */
  void field_repeated_string(int field, const std::vector<std::string>& value)
  {
    for (const auto& elem : value)
      field_string(field, elem);
  }

  /**
   * @brief Function to write a vector of structs to the internal buffer
   */
  template <typename T>
  void field_repeated_struct(int field, const std::vector<T>& value)
  {
    for (const auto& elem : value)
      field_struct(field, elem);
  }

  /**
   * @brief Function to write a vector of struct blobs to the internal
   * buffer
   */
  template <typename T>
  void field_repeated_struct_blob(int field, const std::vector<T>& value)
  {
    for (const auto& elem : value)
      field_blob(field, elem);
  }

  /**
   * @brief Returns the total length of the buffer written
   */
  size_t value() { return struct_size; }
};

}  // namespace orc
}  // namespace io
}  // namespace cudf