[PATCH 2 of 6] export: invoke the file prefetch hook

[Yuya Nishihara]

On Sun, 15 Apr 2018 02:44:06 -0400, Matt Harbison wrote:
> # HG changeset patch
> # User Matt Harbison <matt_harbison at yahoo.com>
> # Date 1523749425 14400
> #      Sat Apr 14 19:43:45 2018 -0400
> # Node ID 1c3654f7ed31e6770cbd97681083bab834554056
> # Parent  de2975df3997148a832ef41425b069fc6f8ff3bc
> export: invoke the file prefetch hook
> 
> cmdutil.exportfile() is only called by shelve, mq and patchbomb.  Those are
> unlikely to mix with lfs, but it may as well be invoked there for completeness.
> 
> diff --git a/mercurial/cmdutil.py b/mercurial/cmdutil.py
> --- a/mercurial/cmdutil.py
> +++ b/mercurial/cmdutil.py
> @@ -1619,6 +1619,12 @@ def export(repo, revs, basefm, fntemplat
>                              the given template.
>          Otherwise: All revs will be written to basefm.
>      '''
> +    files = None
> +    ctxs = [repo[r] for r in revs]
> +    if match:
> +        files = set([f for ctx in ctxs for f in ctx if match(f)])
> +    scmutil.fileprefetchhooks(repo, ctxs, files)

Perhaps we'll need

  fileprefetchhooks(repo, revs, match)

since it may take some time to build a list of ctxs and files.

We can reconstruct a matcher from files by scmutil.matchfiles().