Re: Boost.URL: Something Wicked This Way Comes!

From: Vinnie Falco (vinnie.falco_at_[hidden])
Date: 2021-10-14 01:19:31

On Wed, Oct 13, 2021 at 5:56 PM Gavin Lambert via Boost
<boost_at_[hidden]> wrote:
> part of the point of splitting paths into subcomponents
> is so that you don't have to think about the path separators.

Yeah.

> Some URI libraries will also explicitly iterate "" or "/" as the first
> component (by itself) to indicate the difference between absolute and
> relative URIs, although that could be indicated another way instead.

Currently this is done with

    // returns true if the path has a leading slash ('/')
    bool segments_view::is_absolute() const noexcept;

> In which case it might be best to render the absolute path as:
>...
>      { "/", "path", "to", "file.txt" }

The problem comes with defining the mutation API. How does the user
put a URL into the state above using the segments container interface?

> I would imagine if u.segments() == { "my", "download", "folder", "" }
> before the push_back then after == { "my", "download", "folder",
> "index.htm" }.
>
> But that would be a special case only when the trailing component is empty.

I didn't even think of this, but that's yet another wrinkle.. lol

> The app would have to subsequently push_back("") if it was intending to
> leave a trailing final slash (or just push_back the next component if it
> wasn't finished yet).  But either way it's the app's responsibilty to
> explicitly indicate whether the URL has a trailing slash or not; they
> are semantically different and a library cannot decide that for it.

Given the current container-like interface for modifiable encoded segments:

<https://master.url.cpp.al/url/ref/boost__urls__segments_encoded.html>

What might that API look like that allows the caller to indicate where
the slashes are?

Thanks