JSON Detector

This is a small library to detect boundaries of JSON in a stream.

Why?

In our implementation of a JSON-RPC server, we need to be able to detect the start and the end of a JSON message coming over a socket. A single connection can accept multiple JSON-RPC requests, and the JSON parser we are currently using lacks nice push parsing capabilities.

This library supports asynchronous push parsing and is implemented as a C++ generator. It extracts and co_yield's the messages to the consumer. It does not validate the extracted JSON though, and it can yield a malformed JSON to the consumer. This is the expected behavior, as the proper parsing is handled by another library.

The supported messages are JSON arrays and objects; all other things result in errors, Again, this is the expected behavior because, according to the JSON-RPC 2.0 specification, the request object must be either a JSON object or, in case of a batch request, array.

Build

cmake -B build
cmake --build build
sudo cmake --install build

Dependencies

• wwa-coro;
• GTest (to build unit tests);
• benchmark (to build benchmarks).

All dependencies are installed with vcpkg; please make sure to run git submodule update --init after cloning this repository.

Configuration Options

Option Name	Description	Default Value
BUILD_SHARED_LIBS	Build shared libraries	OFF
BUILD_TESTING	Whether to enable tests	ON
BUILD_BENCHMARKS	Whether to enable benchmarks	ON
INSTALL_JSON_DETECTOR	Whether to enable install targets	ON
ENABLE_MAINTAINER_MODE	Enable maintainer mode (noisy warnings and treat warnings as errors)	OFF
USE_CLANG_TIDY	Use clang-tidy for linting	OFF

Usage

find_package(psb-json-detector CONFIG REQUIRED)
target_link_libraries("${PROJECT_NAME}" PRIVATE psb::json-detector)

#include <iostream>
#include <string>
#include <psb/json_detector/json_detector.h>

int main()
{
    psb::json_detector detector;

    while (!std::cin.eof()) {
        std::string s;
        std::getline(std::cin, s);
        auto&& generator = detector.process(s);
        for (auto& chunk : generator) {
            std::cout << chunk << "\n";
        }
    }

    return detector.is_finished() ? 0 : 1;
}