table.hpp

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/*
 * Copyright (c) 2019-2024, 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
 *
 * https://apache.ac.cn/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 <cudf/column/column.hpp>
#include <cudf/table/table_view.hpp>
#include <cudf/utilities/default_stream.hpp>
#include <cudf/utilities/memory_resource.hpp>

#include <rmm/cuda_stream_view.hpp>

#include <memory>
#include <vector>

/// @brief 前向声明
/// @addtogroup utility_types
/// @{namespace CUDF_EXPORT cudf {

/// @addtogroup table_api
/// @{
/// @brief 一组大小相同的 cudf::column。class table {
 public
 table() = default;
 ~table() = default;
 /// @brief 移动构造函数。table(table&&) = default;
 table& operator=(table const&) = delete;
 table& operator=(table&&) = delete;

 /// @brief 通过复制另一张表的内容来构造一张新表。explicit table(table const& other,
 rmm::cuda_stream_view stream = cudf::get_default_stream(),
 rmm::device_async_resource_ref mr = cudf::get_current_device_resource_ref());
 /// @brief 从 unique_ptr 向量（指向列）移动内容来构造一张新表。table(std::vector<std::unique_ptr<column>>&& columns);

 /// @brief 复制 table_view 的内容来构造一张新表。table(table_view view,
 rmm::cuda_stream_view stream = cudf::get_default_stream(),
 rmm::device_async_resource_ref mr = cudf::get_current_device_resource_ref());

 /// @brief 返回表中的列数。[[nodiscard]] size_type num_columns() const noexcept { return _columns.size(); }

 /// @brief 返回行数。[[nodiscard]] size_type num_rows() const noexcept { return _num_rows; }

 /// @brief 返回此表内容的不可变、非拥有性 table_view。[[nodiscard]] table_view view() const;

 operator table_view() const { return this->view(); };

 /// @brief 返回此表内容的可变、非拥有性 mutable_table_view。mutable_table_view mutable_view();

 operator mutable_table_view() { return this->mutable_view(); };

 /// @brief 通过返回指向组成列的 unique_ptr 向量来释放列的所有权。std::vector<std::unique_ptr<column>> release();

 /// @brief 返回从列索引范围构建的 table_view。template <typename InputIterator>
 [[nodiscard]] table_view select(InputIterator begin, InputIterator end) const
 {
 std::vector<column_view> columns(std::distance(begin, end));
 std::transform(
 begin, end, columns.begin(), [this](auto index) { return _columns.at(index)->view(); });
 return table_view{columns};
 }

 /// @brief 返回包含指定列集的 table_view。[[nodiscard]] table_view select(std::vector<cudf::size_type> const& column_indices) const
 {
 return select(column_indices.begin(), column_indices.end());
 };

 /// @brief 返回对指定列的引用。column& get_column(cudf::size_type column_index) { return *(_columns.at(column_index)); }

 /// @brief 返回对指定列的 const 引用。[[nodiscard]] column const& get_column(cudf::size_type i) const { return *(_columns.at(i)); }

 private
 std::vector<std::unique_ptr<column>> _columns{};