[PATCH 3 of 3] simplemerge: rewrite flag merging loop as expression

[Yuya Nishihara]

On Fri, 5 Jun 2020 16:24:17 +0200, Pierre-Yves David wrote:
> On 6/4/20 4:15 PM, Yuya Nishihara wrote:
> > # HG changeset patch
> > # User Yuya Nishihara <yuya at tcha.org>
> > # Date 1591101897 -32400
> > #      Tue Jun 02 21:44:57 2020 +0900
> > # Node ID 970abb8ea2a2d6a086ebfdd9a1130b2fb777640e
> > # Parent  dba0ac9b68381e9610f25d9991bd623f85cbdefd
> > simplemerge: rewrite flag merging loop as expression
> > 
> > I feel binary operations are more readable.
> 
> The fact also merge "flag removal" become implicit and might be less 
> clear to reader. I like the use of binary operation, but can we add a 
> comment about the removed flag ?

What do you mean with the "flag removal"?
The logic is unchanged, which is to take the common flags and
then add changes from the base.

> > -        flags = localflags & otherflags
> > -        for f in localflags.symmetric_difference(otherflags):
> > -            if f not in baseflags:
> > -                flags.add(f)
> > -        flags = b''.join(sorted(flags))
> > +        commonflags = localflags & otherflags
> > +        addedflags = (localflags ^ otherflags) - baseflags
> > +        flags = b''.join(sorted(commonflags | addedflags))