Re: [boost] [container] static_string ?

"Vinnie Falco via Boost" – 12 septembre 2019 16:06

On Thu, Sep 12, 2019 at 6:19 AM Mike via Boost wrote:

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Not sure, if this counts as substantial...

Yes it does, pretty much anything that is not simply cosmetic (i.e. naming) is substantial :)

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a) to make the string trivially copyable (simply copy the whole storage, not just the bytes actually containing the string). This might make things easier for the optimizer.

The purpose of fixed_capacity_string (see what I did there? LOL) is to facilitate allocation-free string mutation when the algorithm can reasonably impose an upper limit on the size of the resulting string. For example, Beast imposes an generous upper limit on some of the elements which make up the HTTP header. This allows the parser to use a stack based string to perform calculations and avoid allocations.

Why not use a static_vector<char> ? In my experiments replacing strings by vectors of chars has always been a good idea. There is a cost associated with maintaining the null termination of strings, and in some context it is measureable. Given that any modern non-owning interface should use string_view rather than a plain char const*, it seems that it is only when interoperating with C that such a class would be useful. Regards, Julien