toml11/toml/get.hpp

#ifndef TOML11_GET
#define TOML11_GET
#include "result.hpp"
#include "value.hpp"
#include <algorithm>

namespace toml
{

// ============================================================================
// exact toml::* type

template<typename T, typename std::enable_if<
    detail::is_exact_toml_type<T>::value, std::nullptr_t>::type = nullptr>
inline T& get(value& v)
{
    return v.cast<detail::toml_value_t<T>::value>();
}

template<typename T, typename std::enable_if<
    detail::is_exact_toml_type<T>::value, std::nullptr_t>::type = nullptr>
inline T const& get(const value& v)
{
    return v.cast<detail::toml_value_t<T>::value>();
}

template<typename T, typename std::enable_if<
    detail::is_exact_toml_type<T>::value, std::nullptr_t>::type = nullptr>
inline T&& get(value&& v)
{
    return std::move(v.cast<detail::toml_value_t<T>::value>());
}

// ============================================================================
// integer convertible from toml::Integer

template<typename T, typename std::enable_if<detail::conjunction<
    std::is_integral<T>,                            // T is integral
    detail::negation<std::is_same<T, bool>>,        // but not bool
    detail::negation<detail::is_exact_toml_type<T>> // but not toml::integer
    >::value, std::nullptr_t>::type = nullptr>
inline T get(const value& v)
{
    return static_cast<T>(v.cast<value_t::Integer>());
}

// ============================================================================
// floating point convertible from toml::Float

template<typename T, typename std::enable_if<detail::conjunction<
    std::is_floating_point<T>,                      // T is floating_point
    detail::negation<detail::is_exact_toml_type<T>> // but not toml::Float
    >::value, std::nullptr_t>::type = nullptr>
inline T get(const value& v)
{
    return static_cast<T>(v.cast<value_t::Float>());
}

// ============================================================================
// std::string; toml uses its own toml::string, but it should be convertible to
// std::string seamlessly

template<typename T, typename std::enable_if<
    std::is_same<T, std::string>::value, std::nullptr_t>::type = nullptr>
inline std::string& get(value& v)
{
    return v.cast<value_t::String>().str;
}

template<typename T, typename std::enable_if<
    std::is_same<T, std::string>::value, std::nullptr_t>::type = nullptr>
inline std::string const& get(const value& v)
{
    return v.cast<value_t::String>().str;
}

template<typename T, typename std::enable_if<
    std::is_same<T, std::string>::value, std::nullptr_t>::type = nullptr>
inline std::string get(value&& v)
{
    return std::move(v.cast<value_t::String>().str);
}

// ============================================================================
// std::chrono::duration from toml::local_time.

template<typename T, typename std::enable_if<
    detail::is_chrono_duration<T>::value, std::nullptr_t>::type = nullptr>
inline T get(value& v)
{
    return std::chrono::duration_cast<T>(
            std::chrono::microseconds(v.cast<value_t::LocalTime>()));
}

// ============================================================================
// std::chrono::system_clock::time_point from toml::datetime variants

template<typename T, typename std::enable_if<
    std::is_same<std::chrono::system_clock::time_point, T>::value,
    std::nullptr_t>::type = nullptr>
inline T get(value& v)
{
    switch(v.type())
    {
        case value_t::LocalDate:
        {
            return std::chrono::system_clock::time_point(
                    v.cast<value_t::LocalDate>());
        }
        case value_t::LocalDatetime:
        {
            return std::chrono::system_clock::time_point(
                    v.cast<value_t::LocalDatetime>());
        }
        default:
        {
            return std::chrono::system_clock::time_point(
                    v.cast<value_t::OffsetDatetime>());
        }
    }
}

// ============================================================================
// forward declaration to use this recursively. ignore this and go ahead.

template<typename T, typename std::enable_if<detail::conjunction<
    detail::is_container<T>,                        // T is container
    detail::has_resize_method<T>,                   // T::resize(N) works
    detail::negation<detail::is_exact_toml_type<T>> // but not toml::array
    >::value, std::nullptr_t>::type = nullptr>
T get(const value& v);
template<typename T, typename std::enable_if<detail::conjunction<
    detail::is_container<T>,                        // T is container
    detail::negation<detail::has_resize_method<T>>, // no T::resize() exists
    detail::negation<detail::is_exact_toml_type<T>> // not toml::array
    >::value, std::nullptr_t>::type = nullptr>
T get(const value& v);
template<typename T, typename std::enable_if<
    detail::is_std_pair<T>::value, std::nullptr_t>::type = nullptr>
T get(const value& v);
template<typename T, typename std::enable_if<
    detail::is_std_tuple<T>::value, std::nullptr_t>::type = nullptr>
T get(const value& v);
template<typename T, typename std::enable_if<detail::conjunction<
    detail::is_map<T>,                              // T is map
    detail::negation<detail::is_exact_toml_type<T>> // but not toml::table
    >::value, std::nullptr_t>::type = nullptr>
T get(const toml::value& v);

// ============================================================================
// array-like types; most likely STL container, like std::vector, etc.

template<typename T, typename std::enable_if<detail::conjunction<
    detail::is_container<T>,                        // T is container
    detail::has_resize_method<T>,                   // T::resize(N) works
    detail::negation<detail::is_exact_toml_type<T>> // but not toml::array
    >::value, std::nullptr_t>::type = nullptr>
T get(const value& v)
{
    using value_type = typename T::value_type;
    const auto& ar = v.cast<value_t::Array>();

    T container; container.resize(ar.size());
    std::transform(ar.cbegin(), ar.cend(), container.begin(),
                   [](const value& x){return ::toml::get<value_type>(x);});
    return container;
}

// ============================================================================
// array-like types; but does not have resize(); most likely std::array.

template<typename T, typename std::enable_if<detail::conjunction<
    detail::is_container<T>,                        // T is container
    detail::negation<detail::has_resize_method<T>>, // no T::resize() exists
    detail::negation<detail::is_exact_toml_type<T>> // not toml::array
    >::value, std::nullptr_t>::type = nullptr>
T get(const value& v)
{
    using value_type = typename T::value_type;
    const auto& ar = v.cast<value_t::Array>();

    T container;
    if(ar.size() != container.size())
    {
        throw std::out_of_range(detail::format_error_for_value(v, concat_to_string(
            "[erorr] toml::get specified container size is ", container.size(),
            " but there are ", ar.size(), " elements in toml array."), "here"));
    }
    std::transform(ar.cbegin(), ar.cend(), container.begin(),
                   [](const value& x){return ::toml::get<value_type>(x);});
    return container;
}

// ============================================================================
// std::pair.

template<typename T, typename std::enable_if<
    detail::is_std_pair<T>::value, std::nullptr_t>::type = nullptr>
T get(const value& v)
{
    using first_type  = typename T::first_type;
    using second_type = typename T::second_type;

    const auto& ar = v.cast<value_t::Array>();
    if(ar.size() != 2)
    {
        throw std::out_of_range(detail::format_error_for_value(v, concat_to_string(
            "[erorr] toml::get specified std::pair but there are ", ar.size(),
            " elements in toml array."), "here"));
    }
    return std::make_pair(::toml::get<first_type >(ar.at(0)),
                          ::toml::get<second_type>(ar.at(1)));
}

// ============================================================================
// std::tuple.

namespace detail
{

template<typename T, std::size_t ...I>
T get_tuple_impl(const toml::Array& a, index_sequence<I...>)
{
    return std::make_tuple(
        ::toml::get<typename std::tuple_element<I, T>::type>(a.at(I))...);
}

} // detail

template<typename T, typename std::enable_if<
    detail::is_std_tuple<T>::value, std::nullptr_t>::type = nullptr>
T get(const value& v)
{
    const auto& ar = v.cast<value_t::Array>();
    if(ar.size() != std::tuple_size<T>::value)
    {
        throw std::out_of_range(detail::format_error_for_value(v, concat_to_string(
            "[erorr] toml::get specified std::tuple with ",
            std::tuple_size<T>::value, "elements, but there are ", ar.size(),
            " elements in toml array."), "here"));
    }
    return detail::get_tuple_impl<T>(ar,
            detail::make_index_sequence<std::tuple_size<T>::value>{});
}

// ============================================================================
// map-like types; most likely STL map, like std::map or std::unordered_map.

template<typename T, typename std::enable_if<detail::conjunction<
    detail::is_map<T>,                              // T is map
    detail::negation<detail::is_exact_toml_type<T>> // but not toml::table
    >::value, std::nullptr_t>::type = nullptr>
T get(const toml::value& v)
{
    using key_type    = typename T::key_type;
    using mapped_type = typename T::mapped_type;
    static_assert(std::is_convertible<std::string, key_type>::value,
                  "toml::get only supports map type of which key_type is "
                  "convertible from std::string.");
    T map;
    for(const auto& kv : v.cast<value_t::Table>())
    {
        map[key_type(kv.first)] = ::toml::get<mapped_type>(kv.second);
    }
    return map;
}

// ============================================================================
// get_or

template<typename T>
inline typename std::remove_cv<typename std::remove_reference<T>::type>::type
get_or(const toml::Table& tab, const toml::key& ky, T&& opt)
{
    if(tab.count(ky) == 0) {return std::forward<T>(opt);}
    return get<typename std::remove_cv<
        typename std::remove_reference<T>::type>::type>(tab.find(ky)->second);
}

// ============================================================================
// expect

template<typename T>
auto expect(const toml::value& v)
    -> result<decltype(::toml::get<T>(v)), std::string>
{
    try
    {
        return ok(get<T>(v));
    }
    catch(const type_error& te)
    {
        return err(te.what());
    }
}
template<typename T>
auto expect(toml::value& v)
    -> result<decltype(::toml::get<T>(v)), std::string>
{
    try
    {
        return ok(get<T>(v));
    }
    catch(const type_error& te)
    {
        return err(te.what());
    }
}
template<typename T>
auto expect(toml::value&& v)
    -> result<decltype(::toml::get<T>(std::move(v))), std::string>
{
    try
    {
        return ok(get<T>(std::move(v)));
    }
    catch(const type_error& te)
    {
        return err(te.what());
    }
}

} // toml
#endif// TOML11_GET