table_view.hpp

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 * 版权所有 (c) 2019-2024, NVIDIA CORPORATION.
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 *
 * https://apache.ac.cn/licenses/LICENSE-2.0
 *
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 * 不附带任何明示或暗示的担保或条件。
 * 请参阅许可证以了解特定语言的权限和限制。
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 */
#pragma once

#include <cudf/column/column_view.hpp>
#include <cudf/types.hpp>
#include <cudf/utilities/export.hpp>

#include <algorithm>
#include <vector>

namespace CUDF_EXPORT cudf {
namespace detail {
template <typename ColumnView>
class table_view_base {
 static_assert(std::is_same_v<ColumnView, column_view> or
 std::is_same_v<ColumnView, mutable_column_view>,
 "table_view_base can only be instantiated with column_view or "
 "column_view_base.");

 private
 std::vector<ColumnView> _columns{};
 size_type _num_rows{};

 public
 using iterator = decltype(std::begin(_columns));
 using const_iterator = decltype(std::cbegin(_columns));

 explicit table_view_base(std::vector<ColumnView> const& cols);

 iterator begin() noexcept { return std::begin(_columns); }

 [[nodiscard]] const_iterator begin() const noexcept { return std::begin(_columns); }

 iterator end() noexcept { return std::end(_columns); }

 [[nodiscard]] const_iterator end() const noexcept { return std::end(_columns); }

 [[nodiscard]] ColumnView const& column(size_type column_index) const
 {
 return _columns.at(column_index);
 }

 [[nodiscard]] size_type num_columns() const noexcept { return _columns.size(); }

 [[nodiscard]] size_type num_rows() const noexcept { return _num_rows; }

 [[nodiscard]] size_type is_empty() const noexcept { return num_columns() == 0; }

 table_view_base() = default;

 ~table_view_base() = default;

 table_view_base(table_view_base const&) = default;

 table_view_base(table_view_base&&) = default;
 table_view_base& operator=(table_view_base const&) = default;
 table_view_base& operator=(table_view_base&&) = default;
};

bool has_nested_columns(table_view const& table);

} // namespace detail

bool has_nested_columns(table_view const& table);

class table_view : public detail::table_view_base<column_view> {
 using detail::table_view_base<column_view>::table_view_base;

 public
 using ColumnView = column_view;

 table_view() = default;

 table_view(std::vector<table_view> const& views);

 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 this->column(index); });
 return table_view{columns};
 }

 [[nodiscard]] table_view select(std::vector<size_type> const& column_indices) const;
};

class mutable_table_view : public detail::table_view_base<mutable_column_view> {
 using detail::table_view_base<mutable_column_view>::table_view_base;

 public
 using ColumnView = mutable_column_view;

 mutable_table_view() = default;

 [[nodiscard]] mutable_column_view& column(size_type column_index) const
 {
 return const_cast<mutable_column_view&>(table_view_base::column(column_index));
 }
 operator table_view();

 mutable_table_view(std::vector<mutable_table_view> const& views);
};

bool nullable(table_view const& view);

bool has_nulls(table_view const& view);

bool has_nested_nulls(table_view const& input);

bool has_nested_nullable_columns(table_view const& input);

std::vector<column_view> get_nullable_columns(table_view const& table);

table_view scatter_columns(table_view const& source,
 std::vector<size_type> const& map,
 table_view const& target);

namespace detail;
template <typename TableView>
bool is_relationally_comparable(TableView const& lhs, TableView const& rhs);
// @cond
extern template bool is_relationally_comparable<table_view>(table_view const& lhs,
 table_view const& rhs);
extern template bool is_relationally_comparable<mutable_table_view>(mutable_table_view const& lhs,
 mutable_table_view const& rhs);
// @endcond
} // namespace detail
} // namespace CUDF_EXPORT cudf