[PATCH 4 of 4] revset: introduce a 'foo#stack[n]' subscript relation to access stack revisions

[Pierre-Yves David]

On 9/23/19 2:58 PM, Yuya Nishihara wrote:
> On Mon, 23 Sep 2019 10:39:52 +0700, Anton Shestakov wrote:
>> # HG changeset patch
>> # User Anton Shestakov <av6 at dwimlabs.net>
>> # Date 1569139969 -25200
>> #      Sun Sep 22 15:12:49 2019 +0700
>> # Node ID ab8f097abacb8ce0f9cea2bce0924bb2fd3261a2
>> # Parent  07af98a1e730c1ffa6911c9ab2cdcc06d4ffe52d
>> # EXP-Topic stack-object
>> revset: introduce a 'foo#stack[n]' subscript relation to access stack revisions
>>
>> The idea behind making n = 0 cases special is that stack base should be
>> accessible, but only when users ask for it explicitly.
> 
>> +def stackrel(repo, subset, x, rel, z, order):
>> +    a, b = getintrange(z,
>> +                       _('relation subscript must be an integer or a range'),
>> +                       _('relation subscript bounds must be integers'),
>> +                       deffirst=None,
>> +                       deflast=None)
>> +
>> +    s = getset(repo, fullreposet(repo), x)
>> +    if not s:
>> +        return baseset()
>> +
>> +    def getrange(st, a, b):
>> +        start = 1 if a is None else a
>> +        end = len(st.indexedrevs) if b is None else b + 1
> 
> I feel it's weird that stack[:] doesn't include stack[0].

[0] is the "root" of the stack, but not part of it. It is handy to have 
it around when one want to insert and initial commit or test thing 
without any of the stack changes, however it not part of the stack.

For example if you want to update all changesets in the stack you could 
do `hg metaedit --rev '.#stack[:]' --user foobar`. You don't want to 
select s0 it might even be a public changesets.

Cheers,

-- 
Pierre-Yves David