result.hpp

Go to the documentation of this file.

/*##############################################################################
 VSQLite++ - virtuosic bytes SQLite3 C++ wrapper
 
 Copyright (c) 2006-2014 Vinzenz Feenstra vinzenz.feenstra@gmail.com
 All rights reserved.
 
 Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
 
 * Redistributions of source code must retain the above copyright notice,
   this list of conditions and the following disclaimer.
 * Redistributions in binary form must reproduce the above copyright notice,
   this list of conditions and the following disclaimer in the documentation
   and/or other materials provided with the distribution.
 * Neither the name of virtuosic bytes nor the names of its contributors may
   be used to endorse or promote products derived from this software without
   specific prior written permission.
 
 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 POSSIBILITY OF SUCH DAMAGE.
 
##############################################################################*/
#ifndef GUARD_SQLITE_RESULT_HPP_INCLUDED
#define GUARD_SQLITE_RESULT_HPP_INCLUDED
 
#include <chrono>
#include <cstdint>
#include <memory>
#include <optional>
#include <stdexcept>
#include <string>
#include <string_view>
#include <tuple>
#include <type_traits>
#include <vector>
 
#include <sqlite/database_exception.hpp>
#include <sqlite/deprecated.hpp>
#include <sqlite/detail/type_helpers.hpp>
#include <sqlite/ext/variant.hpp>

namespace sqlite {
inline namespace v2 {
    struct query;
    struct result_construct_params_private;
    namespace detail {
        bool end(result_construct_params_private const &);
        void reset(result_construct_params_private &);
    } // namespace detail

    struct result {
    private:
        typedef std::shared_ptr<result_construct_params_private> construct_params;
        friend struct query;
        result(construct_params);
        result(result const &)            = delete;
        result &operator=(result const &) = delete;
 
    public:
        ~result();

        bool next_row();

        inline bool end() const {
            if (!m_params)
                throw std::runtime_error("Invalid memory access");
            return detail::end(*m_params);
        }

        void reset() {
            if (!m_params)
                throw std::runtime_error("Invalid memory access");
            detail::reset(*m_params);
        }

        int get_changes();

        int get_column_count();

        type get_column_type(int idx);

        std::string get_column_decltype(int idx);

        variant_t get_variant(int index);

        size_t get_binary_size(int idx);

        void get_binary(int idx, void *buf, size_t buf_size);

        void get_binary(int idx, std::vector<unsigned char> &vec);

        std::span<const unsigned char> get_binary_span(int idx);

        std::string get_column_name(int idx);

        bool is_null(int idx);

        template <typename T> T get(int idx);

        template <typename... Ts> std::tuple<Ts...> get_tuple(int start_column = 0);
 
    private:
        void access_check(int);
        int get_int(int idx);
        std::int64_t get_int64(int idx);
        std::string get_string(int idx);
        std::string_view get_string_view(int idx);
        double get_double(int idx);
 
    private:
        construct_params m_params;
        int m_columns;
    };

    typedef std::shared_ptr<result> result_type;
 
    namespace detail {
        template <typename... Ts, std::size_t... Index>
        std::tuple<Ts...> tuple_from_row(result &res, int start, std::index_sequence<Index...>) {
            return std::tuple<Ts...>(res.template get<Ts>(start + static_cast<int>(Index))...);
        }
    } // namespace detail
 
    template <typename T> T result::get(int idx) {
        using decayed = detail::decay_t<T>;
        if constexpr (detail::is_optional_v<decayed>) {
            if (is_null(idx)) {
                return std::nullopt;
            }
            using value_type = typename detail::optional_value<decayed>::type;
            return get<value_type>(idx);
        } else if constexpr (detail::is_duration_v<decayed>) {
            auto micros = std::chrono::microseconds{get_int64(idx)};
            return std::chrono::duration_cast<decayed>(micros);
        } else if constexpr (detail::is_time_point_v<decayed>) {
            auto micros   = std::chrono::microseconds{get_int64(idx)};
            auto duration = std::chrono::duration_cast<typename decayed::duration>(micros);
            return decayed(duration);
        } else if constexpr (std::is_enum_v<decayed>) {
            return static_cast<decayed>(get_int64(idx));
        } else if constexpr (std::is_integral_v<decayed> && !std::is_same_v<decayed, bool>) {
            return static_cast<decayed>(get_int64(idx));
        } else if constexpr (std::is_same_v<decayed, bool>) {
            return get_int(idx) != 0;
        } else if constexpr (std::is_floating_point_v<decayed>) {
            return static_cast<decayed>(get_double(idx));
        } else if constexpr (std::is_same_v<decayed, std::string>) {
            return get_string(idx);
        } else if constexpr (std::is_same_v<decayed, std::string_view>) {
            return get_string_view(idx);
        } else if constexpr (detail::is_byte_vector_v<decayed>) {
            std::vector<unsigned char> buffer;
            get_binary(idx, buffer);
            return buffer;
        } else if constexpr (detail::is_unsigned_char_span_v<decayed>) {
            return get_binary_span(idx);
        } else if constexpr (detail::is_byte_span_v<decayed>) {
            auto blob = get_binary_span(idx);
            auto ptr  = reinterpret_cast<std::byte const *>(blob.data());
            return std::span<const std::byte>(ptr, blob.size());
        } else {
            static_assert(detail::always_false_v<decayed>,
                          "Unsupported type for sqlite::result::get<T>");
        }
    }
 
    template <typename... Ts> std::tuple<Ts...> result::get_tuple(int start_column) {
        if (start_column < 0 || start_column + static_cast<int>(sizeof...(Ts)) > m_columns) {
            throw database_exception("Tuple columns exceed result column count.");
        }
        return detail::tuple_from_row<Ts...>(*this, start_column, std::index_sequence_for<Ts...>{});
    }
} // namespace v2
} // namespace sqlite
 
#endif // GUARD_SQLITE_RESULT_HPP_INCLUDED