dagutil: remove unused classes

We only directly use revlogdag in changegroup code. We don't need
all this abstraction. So remove various classes and levels
of inheritance.

Differential Revision: https://phab.mercurial-scm.org/D4325

mercurial/dagutil.py

@@ -1,120 +1,75
 # dagutil.py - dag utilities for mercurial
 #
 # Copyright 2010 Benoit Boissinot <[e-mail]>
 # and Peter Arrenbrecht <[e-mail]>
 #
 # This software may be used and distributed according to the terms of the
 # GNU General Public License version 2 or any later version.
 
 from __future__ import absolute_import
 
 from .node import nullrev
 
-class basedag(object):
-    '''generic interface for DAGs
-
-    terms:
-    "ix" (short for index) identifies a nodes internally,
-    "id" identifies one externally.
-
-    All params are ixs unless explicitly suffixed otherwise.
-    Pluralized params are lists or sets.
-    '''
-
-    def parents(self, ix):
-        '''list of parents ixs of ix'''
-        raise NotImplementedError
-
-    def headsetofconnecteds(self, ixs):
-        '''
-        subset of connected list of ixs so that no node has a descendant in it
-
-        By "connected list" we mean that if an ancestor and a descendant are in
-        the list, then so is at least one path connecting them.
-        '''
-        raise NotImplementedError
-
-class genericdag(basedag):
-    '''generic implementations for DAGs'''
-
-    def headsetofconnecteds(self, ixs):
-        hds = set(ixs)
-        if not hds:
-            return hds
-        for n in ixs:
-            for p in self.parents(n):
-                hds.discard(p)
-        assert hds
-        return hds
-
-
-class revlogbaseddag(basedag):
-    '''generic dag interface to a revlog'''
-
-    def __init__(self, revlog):
-        basedag.__init__(self)
-        self._revlog = revlog
-
-class revlogdag(revlogbaseddag):
+class revlogdag(object):
     '''dag interface to a revlog'''
 
     def __init__(self, revlog):
-        revlogbaseddag.__init__(self, revlog)
+        self._revlog = revlog
 
     def parents(self, ix):
         rlog = self._revlog
         idx = rlog.index
         revdata = idx[ix]
         prev = revdata[5]
         if prev != nullrev:
             prev2 = revdata[6]
             if prev2 == nullrev:
                 return [prev]
             return [prev, prev2]
         prev2 = revdata[6]
         if prev2 != nullrev:
             return [prev2]
         return []
 
     def headsetofconnecteds(self, ixs):
         if not ixs:
             return set()
         rlog = self._revlog
         idx = rlog.index
         headrevs = set(ixs)
         for rev in ixs:
             revdata = idx[rev]
             for i in [5, 6]:
                 prev = revdata[i]
                 if prev != nullrev:
                     headrevs.discard(prev)
         assert headrevs
         return headrevs
 
     def linearize(self, ixs):
         '''linearize and topologically sort a list of revisions
 
         The linearization process tries to create long runs of revs where
         a child rev comes immediately after its first parent. This is done by
         visiting the heads of the given revs in inverse topological order,
         and for each visited rev, visiting its second parent, then its first
         parent, then adding the rev itself to the output list.
         '''
         sorted = []
         visit = list(self.headsetofconnecteds(ixs))
         visit.sort(reverse=True)
         finished = set()
 
         while visit:
             cur = visit.pop()
             if cur < 0:
                 cur = -cur - 1
                 if cur not in finished:
                     sorted.append(cur)
                     finished.add(cur)
             else:
                 visit.append(-cur - 1)
                 visit += [p for p in self.parents(cur)
                           if p in ixs and p not in finished]
         assert len(sorted) == len(ixs)
         return sorted