boost_optional.hpp

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#pragma once
 
/// @file userver/formats/parse/boost_optional.hpp
/// @brief Parsers and converters for boost::optional
/// @ingroup userver_universal userver_formats_parse
 
#include <userver/formats/parse/to.hpp>
 
#include <boost/optional.hpp>
 
USERVER_NAMESPACE_BEGIN
 
/// @brief Generic parsing helpers (`formats::parse::To` and friends).
namespace formats::parse {
 
template <class Value, typename T>
boost::optional<T> Parse(const Value& value, To<boost::optional<T>>) {
    if (value.IsMissing() || value.IsNull()) {
        return boost::none;
    }
    return value.template As<T>();
}
 
template <class Value>
boost::optional<std::nullptr_t> Parse(const Value&, To<boost::optional<std::nullptr_t>>) {
    static_assert(!sizeof(Value), "optional<nullptr_t> is forbidden, check IsNull() instead");
    return nullptr;
}
 
template <class Value, typename T>
boost::optional<T> Convert(const Value& value, To<boost::optional<T>>) {
    if (value.IsMissing() || value.IsNull()) {
        return boost::none;
    }
    return value.template ConvertTo<T>();
}
 
template <class Value>
boost::optional<std::nullptr_t> Convert(const Value&, To<boost::optional<std::nullptr_t>>) {
    static_assert(!sizeof(Value), "optional<nullptr_t> is forbidden, check IsNull() instead");
    return nullptr;
}
 
}  // namespace formats::parse
 
USERVER_NAMESPACE_END