serialize.hpp

/*
  Copyright 2018-2020, Barcelona Supercomputing Center (BSC), Spain
  Copyright 2015-2020, Johannes Gutenberg Universitaet Mainz, Germany

  This software was partially supported by the
  EC H2020 funded project NEXTGenIO (Project ID: 671951, www.nextgenio.eu).

  This software was partially supported by the
  ADA-FS project under the SPPEXA project funded by the DFG.

  SPDX-License-Identifier: MIT
*/

#ifndef GKFS_IO_SERIALIZE_HPP
#define GKFS_IO_SERIALIZE_HPP

#include <nlohmann/json.hpp>

template <typename T>
nlohmann::json 
serialize(const T& object) {

    using json = nlohmann::json; 
    
    json j;

    constexpr auto n = std::tuple_size<decltype(T::properties)>::value;

    refl::for_sequence(std::make_index_sequence<n>{},
        [&](auto i) {
            constexpr auto p = std::get<i>(T::properties);

            //j[p.name] = json {
            //    { "type" , p.type },
            //    { "value" , object.*(p.member) }
            //};

            j[p.name] = object.*(p.member);
        }
    );

    return j;
}

namespace nlohmann {

// ADL specialization for pointers to complete types that 
// we want serialized
template <typename T>
struct adl_serializer<T*> {
    static void to_json(json& j, const T* opt) {
        if (opt) {
            j = *opt;
        } else {
            j = nullptr;
        }
    }
};

// ADL specialization for C strings
template <>
struct adl_serializer<const char*> {
    static void to_json(json& j, const char* opt) {
        if (opt) {
            j = std::string{opt};
        } else {
            j = std::string{};
        }
    }
};

// base serializer for opaque pointers
template <typename T>
struct opaque_ptr_serializer {
    static void to_json(json& j, const T opt) {
        if (opt) {
            j = reinterpret_cast<uint64_t>(opt);
        } else {
            j = nullptr;
        }
    }
};

// ADL specialization for opaque ::DIR* type
template <>
struct adl_serializer<::DIR*> : public opaque_ptr_serializer<::DIR*> {
    using opaque_ptr_serializer<::DIR*>::to_json;
};

// ADL specialization for void* type
template <>
struct adl_serializer<void*> : public opaque_ptr_serializer<void*> {
    using opaque_ptr_serializer<void*>::to_json;
};

// ADL specialization for struct ::timespec type
template <>
struct adl_serializer<struct ::timespec> {
    static void to_json(json& j, const struct ::timespec opt) {

        j = json {
            { "tv_sec",  opt.tv_sec  },
            { "tv_nsec", opt.tv_nsec }
        };
    }
};

#ifdef STATX_TYPE
// ADL specialization for struct ::statx_timestamp type
template <>
struct adl_serializer<struct ::statx_timestamp> {
    static void to_json(json& j, const struct ::statx_timestamp opt) {

        j = json {
            { "tv_sec",  opt.tv_sec  },
            { "tv_nsec", opt.tv_nsec }
        };
    }
};
#endif

// ADL specialization for struct ::dirent type
template <>
struct adl_serializer<struct ::dirent> {
    static void to_json(json& j, const struct ::dirent opt) {

        j = json {
            { "d_ino",    opt.d_ino    },
            { "d_off",    opt.d_off    },
            { "d_reclen", opt.d_reclen },
            { "d_type",   opt.d_type   },
            { "d_name",   opt.d_name   },
        };
    }
};

//std::ostream& 
//operator<<(std::ostream& os, const struct ::dirent& d) {
//    return os << "hello there!\n";
//}

// ADL specialization for struct ::stat type
template <>
struct adl_serializer<struct ::stat> {
    static void to_json(json& j, const struct ::stat opt) {

        j = json {
            { "st_dev",     opt.st_dev     },
            { "st_ino",     opt.st_ino     },
            { "st_mode",    opt.st_mode    },
            { "st_nlink",   opt.st_nlink   },
            { "st_uid",     opt.st_uid     },
            { "st_gid",     opt.st_gid     },
            { "st_rdev",    opt.st_rdev    },
            { "st_size",    opt.st_size    },
            { "st_blksize", opt.st_blksize },
            { "st_blocks",  opt.st_blocks  },
            { "st_atim",    opt.st_atim    },
            { "st_mtim",    opt.st_mtim    },
            { "st_ctim",    opt.st_ctim    }
        };
    }
};

#ifdef STATX_TYPE
// ADL specialization for struct ::statx type
template <>
struct adl_serializer<struct ::statx> {
    static void to_json(json& j, const struct ::statx opt) {

        j = json {
            { "stx_mask",     opt.stx_mask     },
            { "stx_blksize", opt.stx_blksize },
            { "stx_attributes", opt.stx_attributes},
            { "stx_nlink",   opt.stx_nlink   },
            { "stx_uid",     opt.stx_uid     },
            { "stx_gid",     opt.stx_gid     },
            { "stx_mode",    opt.stx_mode    },
            { "stx_ino",     opt.stx_ino     },
            { "stx_size",    opt.stx_size    },
            { "stx_blocks",  opt.stx_blocks  },
            { "stx_attributes_mask", opt.stx_attributes_mask},
            { "stx_atime",    opt.stx_atime    },
            { "stx_btime",    opt.stx_btime    },
            { "stx_ctime",    opt.stx_ctime    },
            { "stx_mtime",    opt.stx_mtime    },

            { "stx_rdev_major",    opt.stx_rdev_major    },
            { "stx_rdev_minor",    opt.stx_rdev_minor    },
            { "stx_dev_major",    opt.stx_dev_major    },
            { "stx_dev_minor",    opt.stx_dev_minor    }           
          
        };
    }
};
#endif

} // namespace nlohmann

namespace fmt {

template <> struct formatter<struct ::dirent> {
    constexpr auto parse(format_parse_context &ctx) {
        // [ctx.begin(), ctx.end()) is a character range that contains a part of
        // the format string starting from the format specifications to be parsed,
        // e.g. in
        //
        //   fmt::format("{:f} - point of interest", point{1, 2});
        //
        // the range will contain "f} - point of interest". The formatter should
        // parse specifiers until '}' or the end of the range. In this example
        // the formatter should parse the 'f' specifier and return an iterator
        // pointing to '}'.

        // Parse the presentation format and store it in the formatter:
        auto it = ctx.begin(), end = ctx.end();

        // Check if reached the end of the range:
        if (it != end && *it != '}')
        throw format_error("invalid format");

        // Return an iterator past the end of the parsed range:
        return it;
    }

    template <typename FormatContext>
        auto format(const struct ::dirent &dirent, FormatContext &ctx) {
            return format_to(ctx.out(), 
                    "struct dirent {{\n"
                    "   d_ino = {};\n" 
                    "   d_off = {};\n"
                    "   d_reclen = {};\n"
                    "   d_type = {};\n"
                    "   d_name = {};\n"
                    "}}",
                    dirent.d_ino,
                    dirent.d_off,
                    dirent.d_reclen,
                    dirent.d_type,
                    dirent.d_name);
        }
};

}

#endif // GKFS_IO_SERIALIZE_HPP