x2struct

Read this in other languages: 简体中文.

---

• Decode json/xml/libconfig/bson to C++ struct or encode C++ struct to json/xml/libconfig/bson
• Convert C++ struct define to Golang struct define(Incomplete, only for testing)

---

• Header file only
• bson/libconfig depend on lib file
• json is enabled by default, modify config.h to enable other:
  • xml need to define macro XTOSTRUCT_XML
  • bson need to define macro XTOSTRUCT_BSON
  • libconfig need to define macro XTOSTRUCT_LIBCONFIG
  • to generate Golang code, need to define macro XTOSTRUCT_GOCODE

---

• support vector/set/map
• support structure nesting

---

EXAMPLE

Take a look at test/example_xxx.cpp or code below

// test.cpp

#include <string>
#include <iostream>
#include <vector>
#include "x2struct.hpp" // include this header file

using namespace std;

// struct define
struct range {
    int min;
    int max;
    XTOSTRUCT(M(min, max)); // add macro in the end of struct define
};

struct example {
    int a;
    string b;
    std::vector<range> rs;  // structure nesting is ok
    XTOSTRUCT(A(a, "_id"), O(b, rs));
};


/*
 g++ -o t test.cpp
 ./t
*/
int main(int argc, char *argv[]) {
    example x;
    
    // json string to struct
    x2struct::X::loadjson("{\"a\":1, \"b\":\"x2struct\", \"rs\":[{\"min\":1, \"max\":2}, {\"min\":10, \"max\":20}]}", x, false);

    // struct to json string
    cout<<x2struct::X::tojson(x)<<endl;
    
    // xml/bson/libconfig is similar
    return 0;
}

USAGE

add macro XTOSTRUCT in the end of struct define. contains all struct members

struct example {
    int a;
    std::string b;
    std::vector<float> c;
    std::vector<int> d;
    XTOSTRUCT(A(a, "id"), O(b), M(c, d)); // add this line
};

Members must in one of A,M or O. A can only put one member at a time, and M/O can put multiple members.

• A: Alias. Used when the member name and key are inconsistent. such as member named UID, and key is "_id"
  Generic alias A(a, "_id") "_id" effective for json/xml/bson/libconfig
   Special alias A(a, "bson:_id")，"_id" only effective for bson. json/xml/libconfig use "a"
   A(a, "id,bson:_id") bson use "_id"，others use "id"

• M: Mandatory. An exception will throw if no key found for mandatory member when decode

• O: Optional. Corresponding to M

---

Conditional decode can be done with XTOSTRUCT_CONDITION/XTOSTRUCT_CONDITION_EQ. For details, please refer to the struct condition in x2struct_test.cpp.

---

If you want to implement some custom types, you can add them in xtypes.h. For details, please refer to XDate. key points:

• Define a class, implement format for encode, parse for decode
• Using the template XType typedef a type

Local Class

Many compilers do not support defining template functions in the local class, while macro XTOSTRUCT defines template functions, so the macro XTOSTRUCT_NT is required in the local class. In addition, applying local class to template functions requires c++0x. support.

XTOSTRUCT_NT is used in the same way as XTOSTRUCT, and you need to specify which types of functions to generate by parameters. Support 4 types: Json/Bson/Xml/Config, such as XTOSTRUCT_NT(Json, Xml)(O(a,b,c), M(d));

IMPORTANT

• Encode/decode json is use rapidjson
• Decode xml is use rapidxml
• Decode bson is use libbson
• Decode libconfig is use libconfig
• Encode of xml/bson is written by myself. Without reference to the RFC, there may be cases where the standard is not met.
• The library of bson/libconfig is precompiled. The environment is: Ubuntu12.04 g++4.9.2. Other environments may need to download the code and recompile if you need to use these two libraries.
• bson/libconfig is not supported under Windows. If you need support, you have to download the code and compile to generate library file.