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Better support for SAX style serialize and deserialize in new version? #554
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Can you be more specific?
if i want to use this to create a json serializer and deserializer for other language like lua.
in lua to serialize a lua table to string , i need to do iterate lua table to create a temp cpp json object first, then use it's dump() method to string.rapidjson give a
rapidjson::Writerclass . with this we can serialize a lua table to string directly in iterating lua table.https://github.com/xpol/lua-rapidjson this project create a lua json serializer and deserializer use rapidjson maybe can help you .
The link is dead. I still don't understand your use case.
You want to iterate over a Lua table and create a JSON serialization from it? But you want to do this without creating an internal JSON representation from the Lua table?
sorry , the link is okay now,
i want to explain my idea clearly, but i think i couldn't, so i write some codeclass lua_json_writer { public: lua_json_writer(lua_State * l, int idx) : L(l), index_(idx), writer_(buffer_) {} ~lua_json_writer() {} const char * encode() { encode_table(index_); return buffer_.GetString(); } private: void encode_value(int val) { int t = lua_type(L, val); if ( t == LUA_TSTRING ) { size_t len = 0; const char * str = lua_tolstring(L, val, &len); writer_.String(str, len); } else if ( t == LUA_TNUMBER ) { if ( lua_isinteger(L, val) ) { writer_.Int64(lua_tointeger(L, val)); } else { writer_.Double(lua_tonumber(L, val)); } } else if ( t == LUA_TBOOLEAN ) { writer_.Bool(!!lua_toboolean(L, val)); } else if ( t == LUA_TTABLE ) { encode_table(val); } } void encode_object(int key, int val) { const char * key_str = lua_tostring(L, key); if ( strcmp(key_str, "__type") == 0 ) { return; } writer_.Key(key_str); encode_value(val); } void encode_array(int key, int val) { if ( lua_type(L, key) != LUA_TNUMBER ) { return; } encode_value(val); } void for_each(std::function<void(lua_json_writer&, int, int)> fx) { for ( lua_pushnil(L); lua_next(L, -2) != 0; lua_pop(L, 1) ) { int top = lua_gettop(L); fx(*this, top - 1, top); } } void encode_table(int idx) { int t = 1; // lua_getfield(L, idx, "__type"); if ( !lua_isnil(L, -1) ) { t = static_cast<int>(lua_tointeger(L, -1)); } lua_pop(L, 1); if ( t == 1 ) { writer_.StartObject(); for_each(&lua_json_writer::encode_object); writer_.EndObject(); } else if ( t == 2 ) { writer_.StartArray(); for_each(&lua_json_writer::encode_array); writer_.EndArray(); } else if ( t == 3 ) { writer_.Null(); } } private: lua_State * L; int index_; rapidjson::StringBuffer buffer_; // rapidjson::Writer<rapidjson::StringBuffer, rapidjson::UTF8<>, rapidjson::ASCII<>> writer_; // };
this code can serialize a lua table to json string , i want json.hpp can do something like this .
You can convert arbitrary types from/to
jsonwith the techniques described in https://github.com/nlohmann/json#arbitrary-types-conversions. But if I understand you correctly, you do not want to create ajsonobject, but directly a JSON compliant string representation from you Lua array, right?yes i don't want to create json object
But how would this library help you if you do not want to use any of its functions?
alright , the rapidjson given
rapidjson::Readerandrapidjson::Writercould do this .
cos i like this library so i want to do it use this . if couldn't i'll give up .
thanks!I do not understand how exactly my library could help you. We provide a C++-style API for JSON values, support to create these values from arbitrary types, and also the possibility to serialize them. But it seems that you need a translation from Lua types to JSON string. This can be implemented manually without the need of any third-party library.
And why exactly don't you want to create an temporary object in the first place? Performance?
it is very useful to do a language binding , Currently we need iterate the object to create a temp cpp json object before serizalize to string .