buffer_io.hpp

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#pragma once
 
/// @file userver/storages/postgres/io/buffer_io.hpp
/// @brief I/O buffer helpers
 
#include <userver/storages/postgres/exceptions.hpp>
#include <userver/storages/postgres/io/traits.hpp>
 
USERVER_NAMESPACE_BEGIN
 
namespace storages::postgres::io {
 
namespace detail {
 
template <typename T, typename Enable = USERVER_NAMESPACE::utils::void_t<>>
struct ParserRequiresTypeCategories : std::false_type {};
 
template <typename T>
struct ParserRequiresTypeCategories<
    T,
    USERVER_NAMESPACE::utils::void_t<
        decltype(std::declval<T&>()(std::declval<const FieldBuffer&>(), std::declval<const TypeBufferCategory&>()))>>
    : std::true_type {};
 
template <typename T>
inline constexpr bool
    kParserRequiresTypeCategories = ParserRequiresTypeCategories<typename traits::IO<T>::ParserType>::value;
 
#ifndef NDEBUG
 
class ReadersRegistrator final {
public:
    ReadersRegistrator(std::type_index type, std::type_index parser_type, const char* base_file);
    void RequireInstance() const;
};
 
// Make instances with different __BASE_FILE__ differ for linker
// NOLINTNEXTLINE(cert-dcl59-cpp,google-build-namespaces)
namespace {
 
template <class Type, class Reader>
struct CheckForBufferReaderODR final {
    static inline ReadersRegistrator content{typeid(Type), typeid(Reader), __BASE_FILE__};
};
 
}  // namespace
 
class WritersRegistrator final {
public:
    WritersRegistrator(std::type_index type, std::type_index formatter_type, const char* base_file);
    void RequireInstance() const;
};
 
// Make instances with different __BASE_FILE__ differ for linker
// NOLINTNEXTLINE(cert-dcl59-cpp,google-build-namespaces)
namespace {
 
template <class Type, class Writer>
struct CheckForBufferWriterODR final {
    static inline WritersRegistrator content{typeid(Type), typeid(Writer), __BASE_FILE__};
};
 
}  // namespace
#endif
 
}  // namespace detail
 
/// @brief Read a value from input buffer
template <typename T>
void ReadBuffer(const FieldBuffer& buffer, T&& value) {
    using ValueType = std::decay_t<T>;
    traits::CheckParser<ValueType>();
    using BufferReader = typename traits::IO<ValueType>::ParserType;
    static_assert(
        !detail::ParserRequiresTypeCategories<BufferReader>::value,
        "Type parser requires knowledge about type categories"
    );
    if (traits::kParserBufferCategory<BufferReader> != buffer.category) {
        throw InvalidParserCategory(
            compiler::GetTypeName<ValueType>(),
            traits::kTypeBufferCategory<ValueType>,
            buffer.category
        );
    }
 
#ifndef NDEBUG
    detail::CheckForBufferReaderODR<T, BufferReader>::content.RequireInstance();
#endif
    BufferReader{std::forward<T>(value)}(buffer);
}
 
template <typename T>
void ReadBuffer(const FieldBuffer& buffer, T&& value, const TypeBufferCategory& categories) {
    using ValueType = std::decay_t<T>;
    traits::CheckParser<ValueType>();
    using BufferReader = typename traits::IO<ValueType>::ParserType;
    if (traits::kParserBufferCategory<BufferReader> != buffer.category) {
        throw InvalidParserCategory(
            compiler::GetTypeName<ValueType>(),
            traits::kTypeBufferCategory<ValueType>,
            buffer.category
        );
    }
 
#ifndef NDEBUG
    detail::CheckForBufferReaderODR<T, BufferReader>::content.RequireInstance();
#endif
 
    if constexpr (detail::ParserRequiresTypeCategories<BufferReader>::value) {
        BufferReader{std::forward<T>(value)}(buffer, categories);
    } else {
        BufferReader{std::forward<T>(value)}(buffer);
    }
}
 
template <typename T>
typename traits::IO<T>::FormatterType BufferWriter(const T& value) {
    using Formatter = typename traits::IO<T>::FormatterType;
#ifndef NDEBUG
    detail::CheckForBufferWriterODR<T, Formatter>::content.RequireInstance();
#endif
    return Formatter(value);
}
 
template <typename T, typename Buffer>
void WriteBuffer(const UserTypes& types, Buffer& buffer, const T& value) {
    traits::CheckFormatter<T>();
    BufferWriter(value)(types, buffer);
}
 
}  // namespace storages::postgres::io
 
USERVER_NAMESPACE_END