view CONTRIBUTING @ 33320:153456f02426

sparse: move function for resolving sparse matcher into core

As part of the move, the function arguments changed so revs are
passed as a list instead of *args. This allows us to use keyword
arguments properly.

Since the plan is to integrate sparse into core and have it
enabled by default, we need to prepare for a sparse matcher
to always be obtained and operated on. As part of the move,
we inserted code that returns an always matcher if sparse
isn't enabled. Some callers in the sparse extension take this
into account and conditionally perform matching depending on
whether the special always matcher is seen. I /think/ this
may have sped up some operations where the extension is
installed but no sparse config is activated.

One thing I'm ensure of in this code is whether os.path.dirname()
is semantically correct. os.posixpath.dirname() (which is
exported as pathutil.dirname) might be a better choise because
all patterns should be using posix directory separators (/)
instead of Windows (\). There's an inline comment that implies
Windows was tested. So hopefully it won't be a problem. We
can improve this in a follow-up. I've added a TODO to track it.

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