[PATCH V2] localrepo: reverse contexts in status

[Pierre-Yves David]

On 05/15/2014 06:09 PM, Sean Farley wrote:
> # HG changeset patch
> # User Sean Farley <sean.michael.farley at gmail.com>
> # Date 1397684088 18000
> #      Wed Apr 16 16:34:48 2014 -0500
> # Node ID b96074a56e0d75b39476e37d91395505b1e01d2f
> # Parent  8844e50911049ffb10c3693b6cfea7e2ea4440c7
> localrepo: reverse contexts in status
>
> This is a slight tweak to how localrepo.status calculates what files have
> changed. By forcing a changectx to be first operator and anything not a
> changectx to be the second operator, we can later exploit this to allow
> refactoring the status operation as a method of a context object.
>
> Furthermore, this change will speed up 'hg diff --reverse' when used with the
> working directory because the code will now hit a fast path without needing to
> calculate an unneeded second manifest.
>
> diff --git a/mercurial/localrepo.py b/mercurial/localrepo.py
> --- a/mercurial/localrepo.py
> +++ b/mercurial/localrepo.py
> @@ -1521,10 +1521,28 @@ class localrepository(object):
>               return mf
>
>           ctx1 = self[node1]
>           ctx2 = self[node2]
>
> +        # This next code block is, admittedly, fragile logic that tests for
> +        # reversing the contexts and wouldn't need to exist if it weren't for
> +        # the fast (and common) code path of comparing the working directory
> +        # with its first parent.
> +        #
> +        # What we're aiming for here is the ability to call:
> +        #
> +        # workingctx.status(parentctx)
> +        #
> +        # If we always built the manifest for each context and compared those,
> +        # then we'd be done. But the special case of the above call means we
> +        # just copy the manifest of the parent.
> +        reversed = False
> +        if (not isinstance(ctx1, context.changectx)
> +            and isinstance(ctx2, context.changectx)):

Not a super fan of isinstance. Do we have any other alternative?
(no is a valid answer)

> +            reversed = True
> +            ctx1, ctx2 = ctx2, ctx1
> +
>           working = ctx2.rev() is None
>           parentworking = working and ctx1 == self['.']
>           match = match or matchmod.always(self.root, self.getcwd())
>           listignored, listclean, listunknown = ignored, clean, unknown
>
> @@ -1579,10 +1597,13 @@ class localrepository(object):
>               removed = mf1.keys()
>
>           if working:
>               modified = ctx2._filtersuspectsymlink(modified)
>
> +        if reversed:
> +            added, removed = removed, added
> +

I see that the deleted/unknown thing disapeared, I assume it did not 
made much sense in the first place?

-- 
Pierre-Yves David