to_json.cpp

/************************************************************************************
*                                                                                   *
*   Copyright (c) 2014 - 2018 Axel Menzel <info@rttr.org>                           *
*                                                                                   *
*   This file is part of RTTR (Run Time Type Reflection)                            *
*   License: MIT License                                                            *
*                                                                                   *
*   Permission is hereby granted, free of charge, to any person obtaining           *
*   a copy of this software and associated documentation files (the "Software"),    *
*   to deal in the Software without restriction, including without limitation       *
*   the rights to use, copy, modify, merge, publish, distribute, sublicense,        *
*   and/or sell copies of the Software, and to permit persons to whom the           *
*   Software is furnished to do so, subject to the following conditions:            *
*                                                                                   *
*   The above copyright notice and this permission notice shall be included in      *
*   all copies or substantial portions of the Software.                             *
*                                                                                   *
*   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR      *
*   IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,        *
*   FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE     *
*   AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER          *
*   LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,   *
*   OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE   *
*   SOFTWARE.                                                                       *
*                                                                                   *
*************************************************************************************/

#include <cstdio>
#include <string>
#include <vector>
#include <array>

#include <iostream>

#define RAPIDJSON_HAS_STDSTRING 1
#include <rapidjson/prettywriter.h> // for stringify JSON
#include <rapidjson/document.h>     // rapidjson's DOM-style API
#include <rttr/type>

using namespace rapidjson;
using namespace rttr;


namespace
{

/////////////////////////////////////////////////////////////////////////////////////////

void to_json_recursively(const instance& obj, PrettyWriter<StringBuffer>& writer);

/////////////////////////////////////////////////////////////////////////////////////////

bool write_variant(const variant& var, PrettyWriter<StringBuffer>& writer);

bool write_atomic_types_to_json(const type& t, const variant& var, PrettyWriter<StringBuffer>& writer)
{
    if (t.is_arithmetic())
    {
        if (t == type::get<bool>())
            writer.Bool(var.to_bool());
        else if (t == type::get<char>())
            writer.Bool(var.to_bool());
        else if (t == type::get<int8_t>())
            writer.Int(var.to_int8());
        else if (t == type::get<int16_t>())
            writer.Int(var.to_int16());
        else if (t == type::get<int32_t>())
            writer.Int(var.to_int32());
        else if (t == type::get<int64_t>())
            writer.Int64(var.to_int64());
        else if (t == type::get<uint8_t>())
            writer.Uint(var.to_uint8());
        else if (t == type::get<uint16_t>())
            writer.Uint(var.to_uint16());
        else if (t == type::get<uint32_t>())
            writer.Uint(var.to_uint32());
        else if (t == type::get<uint64_t>())
            writer.Uint64(var.to_uint64());
        else if (t == type::get<float>())
            writer.Double(var.to_double());
        else if (t == type::get<double>())
            writer.Double(var.to_double());

        return true;
    }
    else if (t.is_enumeration())
    {
        bool ok = false;
        auto result = var.to_string(&ok);
        if (ok)
        {
            writer.String(var.to_string());
        }
        else
        {
            ok = false;
            auto value = var.to_uint64(&ok);
            if (ok)
                writer.Uint64(value);
            else
                writer.Null();
        }

        return true;
    }
    else if (t == type::get<std::string>())
    {
        writer.String(var.to_string());
        return true;
    }

    return false;
}

/////////////////////////////////////////////////////////////////////////////////////////

static void write_array(const variant_sequential_view& view, PrettyWriter<StringBuffer>& writer)
{
    writer.StartArray();
    for (const auto& item : view)
    {
        if (item.is_sequential_container())
        {
            write_array(item.create_sequential_view(), writer);
        }
        else
        {
            variant wrapped_var = item.extract_wrapped_value();
            type value_type = wrapped_var.get_type();
            if (value_type.is_arithmetic() || value_type == type::get<std::string>() || value_type.is_enumeration())
            {
                write_atomic_types_to_json(value_type, wrapped_var, writer);
            }
            else // object
            {
                to_json_recursively(wrapped_var, writer);
            }
        }
    }
    writer.EndArray();
}


/////////////////////////////////////////////////////////////////////////////////////////

static void write_associative_container(const variant_associative_view& view, PrettyWriter<StringBuffer>& writer)
{
    static const string_view key_name("key");
    static const string_view value_name("value");

    writer.StartArray();

    if (view.is_key_only_type())
    {
        for (auto& item : view)
        {
            write_variant(item.first, writer);
        }
    }
    else
    {
        for (auto& item : view)
        {
            writer.StartObject();
            writer.String(key_name.data(), static_cast<rapidjson::SizeType>(key_name.length()), false);

            write_variant(item.first, writer);

            writer.String(value_name.data(), static_cast<rapidjson::SizeType>(value_name.length()), false);

            write_variant(item.second, writer);

            writer.EndObject();
        }
    }

    writer.EndArray();
}

/////////////////////////////////////////////////////////////////////////////////////////

bool write_variant(const variant& var, PrettyWriter<StringBuffer>& writer)
{
    auto value_type = var.get_type();
    auto wrapped_type = value_type.is_wrapper() ? value_type.get_wrapped_type() : value_type;
    bool is_wrapper = wrapped_type != value_type;

    if (write_atomic_types_to_json(is_wrapper ? wrapped_type : value_type,
                                   is_wrapper ? var.extract_wrapped_value() : var, writer))
    {
    }
    else if (var.is_sequential_container())
    {
        write_array(var.create_sequential_view(), writer);
    }
    else if (var.is_associative_container())
    {
        write_associative_container(var.create_associative_view(), writer);
    }
    else
    {
        auto child_props = is_wrapper ? wrapped_type.get_properties() : value_type.get_properties();
        if (!child_props.empty())
        {
            to_json_recursively(var, writer);
        }
        else
        {
            bool ok = false;
            auto text = var.to_string(&ok);
            if (!ok)
            {
                writer.String(text);
                return false;
            }

            writer.String(text);
        }
    }

    return true;
}

/////////////////////////////////////////////////////////////////////////////////////////

void to_json_recursively(const instance& obj2, PrettyWriter<StringBuffer>& writer)
{
    writer.StartObject();
    instance obj = obj2.get_type().get_raw_type().is_wrapper() ? obj2.get_wrapped_instance() : obj2;

    auto prop_list = obj.get_derived_type().get_properties();
    for (auto prop : prop_list)
    {
        if (prop.get_metadata("NO_SERIALIZE"))
            continue;

        variant prop_value = prop.get_value(obj);
        if (!prop_value)
            continue; // cannot serialize, because we cannot retrieve the value

        const auto name = prop.get_name();
        writer.String(name.data(), static_cast<rapidjson::SizeType>(name.length()), false);
        if (!write_variant(prop_value, writer))
        {
            std::cerr << "cannot serialize property: " << name << std::endl;
        }
    }

    writer.EndObject();
}

} // end namespace anonymous

/////////////////////////////////////////////////////////////////////////////////////////
/////////////////////////////////////////////////////////////////////////////////////////
/////////////////////////////////////////////////////////////////////////////////////////

namespace io
{

/////////////////////////////////////////////////////////////////////////////////////////

std::string to_json(rttr::instance obj)
{
    if (!obj.is_valid())
        return std::string();

    StringBuffer sb;
    PrettyWriter<StringBuffer> writer(sb);

    to_json_recursively(obj, writer);

    return sb.GetString();
}

/////////////////////////////////////////////////////////////////////////////////////////

} // end namespace io