robot/include/asio2/bho/mysql/impl/row_impl.ipp

//
// Copyright (c) 2019-2023 Ruben Perez Hidalgo (rubenperez038 at gmail dot com)
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//

#ifndef BHO_MYSQL_IMPL_ROW_IMPL_IPP
#define BHO_MYSQL_IMPL_ROW_IMPL_IPP

#pragma once

#include <asio2/bho/mysql/detail/config.hpp>
#include <asio2/bho/mysql/detail/row_impl.hpp>

namespace bho {
namespace mysql {
namespace detail {

BHO_MYSQL_STATIC_OR_INLINE
std::size_t get_string_size(field_view f) noexcept
{
    switch (f.kind())
    {
    case field_kind::string: return f.get_string().size();
    case field_kind::blob: return f.get_blob().size();
    default: return 0;
    }
}

BHO_MYSQL_STATIC_OR_INLINE
unsigned char* copy_string(unsigned char* buffer_it, field_view& f) noexcept
{
    auto str = f.get_string();
    if (!str.empty())
    {
        std::memcpy(buffer_it, str.data(), str.size());
        f = field_view(string_view(reinterpret_cast<const char*>(buffer_it), str.size()));
        buffer_it += str.size();
    }
    return buffer_it;
}

BHO_MYSQL_STATIC_OR_INLINE
unsigned char* copy_blob(unsigned char* buffer_it, field_view& f) noexcept
{
    auto b = f.get_blob();
    if (!b.empty())
    {
        std::memcpy(buffer_it, b.data(), b.size());
        f = field_view(blob_view(buffer_it, b.size()));
        buffer_it += b.size();
    }
    return buffer_it;
}

BHO_MYSQL_STATIC_OR_INLINE
std::size_t copy_string_as_offset(unsigned char* buffer_first, std::size_t offset, field_view& f) noexcept
{
    auto str = f.get_string();
    if (!str.empty())
    {
        std::memcpy(buffer_first + offset, str.data(), str.size());
        f = detail::access::construct<field_view>(detail::string_view_offset{offset, str.size()}, false);
        return str.size();
    }
    return 0;
}

BHO_MYSQL_STATIC_OR_INLINE
std::size_t copy_blob_as_offset(unsigned char* buffer_first, std::size_t offset, field_view& f) noexcept
{
    auto str = f.get_blob();
    if (!str.empty())
    {
        std::memcpy(buffer_first + offset, str.data(), str.size());
        f = detail::access::construct<field_view>(detail::string_view_offset{offset, str.size()}, true);
        return str.size();
    }
    return 0;
}

BHO_MYSQL_STATIC_OR_INLINE
void copy_strings(std::vector<field_view>& fields, std::vector<unsigned char>& string_buffer)
{
    // Calculate the required size for the new strings
    std::size_t size = 0;
    for (auto f : fields)
    {
        size += get_string_size(f);
    }

    // Make space. The previous fields should be in offset form
    string_buffer.resize(string_buffer.size() + size);

    // Copy strings and blobs
    unsigned char* buffer_it = string_buffer.data();
    for (auto& f : fields)
    {
        switch (f.kind())
        {
        case field_kind::string: buffer_it = copy_string(buffer_it, f); break;
        case field_kind::blob: buffer_it = copy_blob(buffer_it, f); break;
        default: break;
        }
    }
    BHO_ASSERT(buffer_it == string_buffer.data() + size);
}

BHO_MYSQL_STATIC_OR_INLINE
field_view offset_to_string_view(field_view fv, const std::uint8_t* buffer_first) noexcept
{
    auto& impl = detail::access::get_impl(fv);
    if (impl.is_string_offset())
    {
        return field_view(string_view(
            reinterpret_cast<const char*>(buffer_first) + impl.repr.sv_offset_.offset,
            impl.repr.sv_offset_.size
        ));
    }
    else if (impl.is_blob_offset())
    {
        return field_view(blob_view(buffer_first + impl.repr.sv_offset_.offset, impl.repr.sv_offset_.size));
    }
    else
    {
        return fv;
    }
}

}  // namespace detail
}  // namespace mysql
}  // namespace bho

bho::mysql::detail::row_impl::row_impl(const field_view* fields, std::size_t size)
    : fields_(fields, fields + size)
{
    copy_strings(fields_, string_buffer_);
}

bho::mysql::detail::row_impl::row_impl(const row_impl& rhs) : fields_(rhs.fields_)
{
    copy_strings(fields_, string_buffer_);
}

bho::mysql::detail::row_impl& bho::mysql::detail::row_impl::operator=(const row_impl& rhs)
{
    assign(rhs.fields_.data(), rhs.fields_.size());
    return *this;
}

void bho::mysql::detail::row_impl::assign(const field_view* fields, std::size_t size)
{
    // Protect against self-assignment. This is valid as long as we
    // don't implement sub-range operators (e.g. row_view[2:4])
    if (fields_.data() == fields)
    {
        BHO_ASSERT(fields_.size() == size);
    }
    else
    {
        fields_.assign(fields, fields + size);
        string_buffer_.clear();
        copy_strings(fields_, string_buffer_);
    }
}

void bho::mysql::detail::row_impl::copy_strings_as_offsets(std::size_t first, std::size_t num_fields)
{
    // Preconditions
    BHO_ASSERT(first <= fields_.size());
    BHO_ASSERT(first + num_fields <= fields_.size());

    // Calculate the required size for the new strings
    std::size_t size = 0;
    for (std::size_t i = first; i < first + num_fields; ++i)
    {
        size += get_string_size(fields_[i]);
    }

    // Make space. The previous fields should be in offset form
    std::size_t old_string_buffer_size = string_buffer_.size();
    string_buffer_.resize(old_string_buffer_size + size);

    // Copy strings and blobs
    std::size_t offset = old_string_buffer_size;
    for (std::size_t i = first; i < first + num_fields; ++i)
    {
        auto& f = fields_[i];
        switch (f.kind())
        {
        case field_kind::string: offset += copy_string_as_offset(string_buffer_.data(), offset, f); break;
        case field_kind::blob: offset += copy_blob_as_offset(string_buffer_.data(), offset, f); break;
        default: break;
        }
    }
    BHO_ASSERT(offset == string_buffer_.size());
}

void bho::mysql::detail::row_impl::offsets_to_string_views()
{
    for (auto& f : fields_)
        f = offset_to_string_view(f, string_buffer_.data());
}

#endif