CodablePP

This C++ library provides Codable protocol from Swift.
It may be useful if you have C++ server for iOS or macOS application.
Library methods have very similar syntax to Swift's version.

Documentation

Before using encoding and decoding methods and Codable class, you must import 2 headers:

#include "Codable.h"
#include "JSON.h"

If you want to make class Codable as you do in Swift, you must choose Codable class as a base class.
For example, if you have class PhoneBook, then its Codable version will look like this:

class PhoneBook: public Codable {};

Also you must provide class with implementations of 2 virtual methods as you do in Swift and 1 initializer without arguments:

void encode(CoderContainer* container) {}
void decode(CoderContainer* container) {}
PhoneBook() {}

By default, there is only one Coder type - JSON. But you have to check for type and perform dynamic_cast. Here is an example for our class PhoneBook:

void encode(CoderContainer* container) {
    if (container->type == CoderType::json) {
        JSONEncodeContainer* jsonContainer = dynamic_cast<JSONEncodeContainer*>(container);
        jsonContainer->encode(contacts, "contacts");
    }
}

After that we can encode everything we want. In the example above we encode contacts of phone book.
The contacts variable has type vector<Contact>. Contact class also must have Codable class as a base class.
Notice that this library supports only vectors for JSON arrays. Simple arrays won't be eligible for that. Decoding has the same logic:

void decode(CoderContainer* container) {
    if (container->type == CoderType::json) {
        JSONDecodeContainer* jsonContainer = dynamic_cast<JSONDecodeContainer*>(container);
        contacts = jsonContainer->decode(vector<Contact>(), "contacts");
    }
}

We must provide decoder with any variable with type we want to decode. In our case it is vector<Contact>().
The second argument in both encoding and decoding methods is key for field in JSON. It must match with key in client-application in Swift.

So, we made our Phonebook class Codable. Now we can encode it using JSONEncoder as easy as in Swift

JSONEncoder encoder;
auto encodeContainer = encoder.container();
encodeContainer.encode(book);
cout << encodeContainer.content << endl;

and decode it back to Phonebook class

JSONDecoder decoder;
auto container = decoder.container(encodeContainer.content);
auto decodeBook = container.decode(PhoneBook());