view tests/test-issue1993.t @ 32903:27932a76a88d

dagop: split module hosting DAG-related algorithms from revset

This module hosts the following functions. They are somewhat similar (e.g.
scanning revisions using heap queue or stack) and seem non-trivial in
algorithmic point of view.

 - _revancestors()
 - _revdescendants()
 - reachableroots()
 - _toposort()

I was thinking of adding revset._fileancestors() generator for better follow()
implementation, but it would be called from context.py as well. So I decided
to create new module.

Naming is hard. I couldn't come up with any better module name, so it's called
"dag operation" now. I rejected the following candidates:

 - ancestor.py - existing, revlog-level DAG algorithm
 - ancestorset.py - doesn't always return a set
 - dagalgorithm.py - hard to type
 - dagutil.py - existing
 - revancestor.py - I want to add fileancestors()

  % wc -l mercurial/dagop.py mercurial/revset.py
    339 mercurial/dagop.py
   2020 mercurial/revset.py
   2359 total

  $ hg init a
  $ cd a
  $ echo a > a
  $ hg ci -Am0
  adding a
  $ echo b > b
  $ hg ci -Am1
  adding b
  $ hg tag -r0 default
  warning: tag default conflicts with existing branch name
  $ hg log
  changeset:   2:30a83d1e4a1e
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     Added tag default for changeset f7b1eb17ad24
  
  changeset:   1:925d80f479bb
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     1
  
  changeset:   0:f7b1eb17ad24
  tag:         default
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     0
  
  $ hg update 'tag(default)'
  0 files updated, 0 files merged, 2 files removed, 0 files unresolved
  $ hg parents
  changeset:   0:f7b1eb17ad24
  tag:         default
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     0
  
  $ hg update 'branch(default)'
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg parents
  changeset:   2:30a83d1e4a1e
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     Added tag default for changeset f7b1eb17ad24
  

  $ cd ..