Add JSON check

[nlohmann]

The nlohmann/json has a function accept which just checks whether an input is valid JSON. As no internal structure is built, this check is much faster than parsing. Maybe other libraries have this as well, and benchmarking it could be helpful.

[Loki-Astari]

The test "Parse" is used to perform this exact test.

JsonBenchmark/src/benchmark/PerformanceChecker.cpp

Lines 152 to 170 in debd1ce

	void PerformanceChecker::executeParse(TestBase const& parser, Test const& test)
	{
	double minDuration = std::chrono::duration<double>::max().count();
	Output generator(options, parser, test, "Parse", "1", minDuration);
	for (int loop = 0; loop < loopCount; ++loop)
	{
	TestSetUp testSetUp(parser, setupName(test), true);
	std::unique_ptr<ParseResultBase> result;
	double duration = timeExecution([&parser, &test, &result]()
	{ result.reset(parser.Parse(test.input.c_str(), test.input.size()));});
	if (!result)
	{
	return;
	}
	minDuration = std::min(minDuration, duration);
	}
	generator.setPass();
	}

You will notice that nothing is done with the result of the parse.
Though it is required to indicate that the test passed (returning a nullptr indicates failure.

In your case we simply need to modify the corresponding test implementation:

JsonBenchmark/src/ThirdParty/nlohmannTest.cpp

Lines 69 to 79 in debd1ce

	virtual ParseResultBase* Parse(const char* j, size_t length) const {
	(void)length;
	NlohmannParseResult* pr = new NlohmannParseResult;
	try {
	pr->root = json::parse(j);
	}
	catch (...) {
	delete pr;
	return 0;
	}
	return pr;

If you feel like providing a pull request with this change I would be be happy to merge.