[RFC] revision sets

Matt Mackall mpm at selenic.com
Mon Apr 19 17:32:41 CDT 2010


Right now we have a notion of revision ranges, ie:

 hg log -r 0:1.0

Internally, we iterate over this with something like:

 for rev in commandutil.revrange(opts['rev']):

I've been talking about expanding this into a more powerful system that
would allow specifying dates, keywords, branches, etc. My current
thought is to make it look like this:

 hg log -r "branch(foo) and keyword(bar) and date(mar 1 - apr 1)"

Which would be identical to:

 hg log -b foo -k bar -d "mar 1 - apr 1"

but would magically work anywhere -r ranges were accepted (export, push,
etc.).

Further, we'd be able to add lots of interesting primitives:

 hg log -r "descendant(parent2(1.0)) and ancestor(2.0) and
author(george) and sorted(date) and reversed()"

Read that as: every cset that is descended from the second parent of
revision 1.0 and is also an ancestor of 2.0 and was written by george,
sorted by date in reverse order.

revrange would be replaced by a new revset function that would parse the
query/queries and build an iterator. Some of the operations, like
keyword() and author(), would obviously be fairly expensive and many
would fail to work (at least for now) on remote repos.

I've pitched an idea like this before, usually with a weird
operator-intensive syntax. This time, I think the right thing is an
easily-read but more verbose query language.

Steps to get from here to there:

- change all callers of revrange to revset
- design a BNF for the revset query language
- build a query parser/"compiler"
- add filters for the query functions
- simplify some of the existing options (like -d and -k) by turning them
into queries internally

Thoughts?

-- 
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