Re: JSON and no-alloc

From: Vinnie Falco (vinnie.falco_at_[hidden])
Date: 2023-08-14 19:05:52

On Mon, Aug 14, 2023 at 11:46 AM Marc Oscar Singer via Boost-users <
boost-users_at_[hidden]> wrote:

> I'm targeting the boost JSON library for an embedded target.  There
> appears to be one place where there could be either a beneficial new
> feature, or the feature exists and I'm not seeing it.
>
> The section about Avoiding Dynamic Allocation is close to what we'd like
> to see, except that we don't want to depend on a stack buffer for value
> data.  All of the text of the JSON message is present in the string view.
> It would be desirable to reference the values from there.
>
When it comes to building a JSON library, there are many tradeoffs that
must be made. Tailoring the library for one use-case necessarily inhibits
other use cases or makes them less efficient. The design of Boost.JSON is
based on offering an efficient and flexible "value type." That is, objects
of type boost::json::value, which implement a form of variant across the
seven JSON native types: null, bool, integer, floating point, string,
array, and object.

What you are describing is a completely different JSON library. For example
your model would be read-only, while instances of boost::json::value are
also writeable. Implementing the feature you describe using
Boost.JSON's existing types would be, to put it simply, a huge hack and
incur enormous technical debt. It would be much cleaner to simply offer
that as its own library. Or perhaps in another namespace under Boost.JSON,
which reuses very little of the existing Boost.JSON code.

However, this effort is unnecessary because there is already a great
library that does what you describe, and that is simdjson. Check it out:

<https://github.com/simdjson/simdjson>

Would this suit your needs?

Regards