collation.hpp

//
// Copyright (c) 2022 Klemens Morgenstern (klemens.morgenstern@gmx.net)
//
// 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 BOOST_SQLITE_COLLATION_HPP
#define BOOST_SQLITE_COLLATION_HPP
 
#include <boost/sqlite/connection.hpp>
#include <boost/sqlite/detail/exception.hpp>
 
BOOST_SQLITE_BEGIN_NAMESPACE
 
 
template<typename Func>
void create_collation(
    connection & conn,
    cstring_ref name,
    Func && func,
    typename std::enable_if<
        std::is_convertible<
            decltype(func(string_view(), string_view())),
            int>::value,
        system::error_code>::type & ec)
{
    using func_type = typename std::decay<Func>::type;
    auto f = new (memory_tag{}) func_type(std::forward<Func>(func));
    if (f == nullptr)
    {
      BOOST_SQLITE_ASSIGN_EC(ec, SQLITE_NOMEM);
      return;
    }
    auto res = sqlite3_create_collation_v2(
        conn.handle(),
        name.c_str(),
        SQLITE_UTF8,
        f,
        +[](void * data, int len_l, const void * str_l, int len_r, const void * str_r) -> int
        {
          string_view l(static_cast<const char*>(str_l), len_l);
          string_view r(static_cast<const char*>(str_r), len_r);
          auto & impl = (*static_cast<func_type*>(data));
          static_assert(noexcept(impl(l, r)),
                        "Collation function must be noexcept");
          return impl(l, r);
        },
        +[](void * p) { delete_(static_cast<func_type*>(p)); }
      );
    if (res != SQLITE_OK)
      BOOST_SQLITE_ASSIGN_EC(ec, res);
}
 
 
template<typename Func>
auto create_collation(
    connection & conn,
    cstring_ref name,
    Func && func)
#if !defined(BOOST_SQLITE_GENERATING_DOCS)
    -> typename std::enable_if<
          std::is_convertible<
              decltype(func(string_view(), string_view())),
              int>::value>::type
#endif
{
    system::error_code ec;
    create_collation(conn, name, std::forward<Func>(func), ec);
    if (ec)
        detail::throw_error_code(ec, BOOST_CURRENT_LOCATION);
}
 
BOOST_SQLITE_END_NAMESPACE
 
#endif //BOOST_SQLITE_COLLATION_HPP