mysql/detail/rows_iterator.hpp

0001 //
0002 // Copyright (c) 2019-2023 Ruben Perez Hidalgo (rubenperez038 at gmail dot com)
0003 //
0004 // Distributed under the Boost Software License, Version 1.0. (See accompanying
0005 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
0006 //
0007
0008 #ifndef BOOST_MYSQL_DETAIL_ROWS_ITERATOR_HPP
0009 #define BOOST_MYSQL_DETAIL_ROWS_ITERATOR_HPP
0010
0011 #include <boost/mysql/field_view.hpp>
0012 #include <boost/mysql/row.hpp>
0013 #include <boost/mysql/row_view.hpp>
0014
0015 #include <boost/mysql/detail/access.hpp>
0016
0017 #include <cstddef>
0018 #include <cstdint>
0019 #include <iterator>
0020
0021 namespace boost {
0022 namespace mysql {
0023 namespace detail {
0024
0025 inline row_view row_slice(const field_view* fields, std::size_t num_columns, std::size_t offset) noexcept
0026 {
0027     return access::construct<row_view>(fields + num_columns * offset, num_columns);
0028 }
0029
0030 class rows_iterator
0031 {
0032     const field_view* fields_{nullptr};
0033     std::size_t num_columns_{0};
0034     std::size_t row_num_{0};
0035
0036 public:
0037     using value_type = row;
0038     using reference = row_view;
0039     using pointer = row_view;
0040     using difference_type = std::ptrdiff_t;
0041     using iterator_category = std::random_access_iterator_tag;
0042
0043     rows_iterator() = default;
0044     rows_iterator(const field_view* fields, std::size_t num_columns, std::size_t rownum) noexcept
0045         : fields_(fields), num_columns_(num_columns), row_num_(rownum)
0046     {
0047     }
0048
0049     rows_iterator& operator++() noexcept
0050     {
0051         ++row_num_;
0052         return *this;
0053     }
0054     rows_iterator operator++(int) noexcept
0055     {
0056         auto res = *this;
0057         ++(*this);
0058         return res;
0059     }
0060     rows_iterator& operator--() noexcept
0061     {
0062         --row_num_;
0063         return *this;
0064     }
0065     rows_iterator operator--(int) noexcept
0066     {
0067         auto res = *this;
0068         --(*this);
0069         return res;
0070     }
0071     rows_iterator& operator+=(std::ptrdiff_t n) noexcept
0072     {
0073         row_num_ += n;
0074         return *this;
0075     }
0076     rows_iterator& operator-=(std::ptrdiff_t n) noexcept
0077     {
0078         row_num_ -= n;
0079         return *this;
0080     }
0081     rows_iterator operator+(std::ptrdiff_t n) const noexcept
0082     {
0083         return rows_iterator(fields_, num_columns_, row_num_ + n);
0084     }
0085     rows_iterator operator-(std::ptrdiff_t n) const noexcept
0086     {
0087         return rows_iterator(fields_, num_columns_, row_num_ - n);
0088     }
0089     std::ptrdiff_t operator-(rows_iterator rhs) const noexcept { return row_num_ - rhs.row_num_; }
0090
0091     pointer operator->() const noexcept { return **this; }
0092     reference operator*() const noexcept { return (*this)[0]; }
0093     reference operator[](std::ptrdiff_t i) const noexcept
0094     {
0095         return row_slice(fields_, num_columns_, row_num_ + i);
0096     }
0097
0098     bool operator==(rows_iterator rhs) const noexcept { return row_num_ == rhs.row_num_; }
0099     bool operator!=(rows_iterator rhs) const noexcept { return !(*this == rhs); }
0100     bool operator<(rows_iterator rhs) const noexcept { return row_num_ < rhs.row_num_; }
0101     bool operator<=(rows_iterator rhs) const noexcept { return row_num_ <= rhs.row_num_; }
0102     bool operator>(rows_iterator rhs) const noexcept { return row_num_ > rhs.row_num_; }
0103     bool operator>=(rows_iterator rhs) const noexcept { return row_num_ >= rhs.row_num_; }
0104 };
0105
0106 inline rows_iterator operator+(std::ptrdiff_t n, rows_iterator it) noexcept { return it + n; }
0107
0108 }  // namespace detail
0109 }  // namespace mysql
0110 }  // namespace boost
0111
0112 #endif