[PATCH 08 of 17 RFC] clfilter: introduce `filteredrevs` attribute on changelog

[pierre-yves.david at logilab.fr]

# HG changeset patch
# User Pierre-Yves David <pierre-yves.david at logilab.fr>
# Date 1346675395 -7200
# Node ID f4109d3aeff82a632b8ec13496a18a3b1b0c8574
# Parent  4a4dafde8898d6cc4fa9c77cfe10125afc63dd87
clfilter: introduce `filteredrevs` attribute on changelog

This changeset allows changelog object to be "filtered". You can assign a set of
revision numbers to the `changelog.filteredrevs` attributes. The changelog will
then pretends these revision does not exists in this repo.

A few methods need to be altered to achieve this behavior:

- tip
- __iter_
- irevs
- hasnode
- headrevs

For consistency and to help debugging, the following methods are altered too.
Tests tend to show it's not necessary to alter them but have them raise proper
exception helps to detect bad acces to filtered revisions.

- rev
- node
- linkrev
- parentrevs
- flags

The following methods would also need alteration for consistency purpose but
this is non-trivial and not done yet.

- nodemap
- strip

The C version of headrevs is not run if there is any revision to filter. It'll
need a proper rewrite later to restore performance.

diff --git a/mercurial/changelog.py b/mercurial/changelog.py
--- a/mercurial/changelog.py
+++ b/mercurial/changelog.py
@@ -7,12 +7,15 @@
 
 from node import bin, hex, nullid
 from i18n import _
 import util, error, revlog, encoding
 
+LookupError = error.LookupError
+
 _defaultextra = {'branch': 'default'}
 
+
 def _string_escape(text):
     """
     >>> d = {'nl': chr(10), 'bs': chr(92), 'cr': chr(13), 'nul': chr(0)}
     >>> s = "ab%(nl)scd%(bs)s%(bs)sn%(nul)sab%(cr)scd%(bs)s%(nl)s" % d
     >>> s
@@ -118,10 +121,94 @@ class changelog(revlog.revlog):
             self.version &= ~revlog.REVLOGGENERALDELTA
             self._generaldelta = False
         self._realopener = opener
         self._delayed = False
         self._divert = False
+        self.filteredrevs = ()
+
+    def tip(self):
+        """filtered version of revlog.tip"""
+        for i in xrange(len(self) -1, -2, -1):
+            if i not in self.filteredrevs:
+                return self.node(i)
+
+    def __iter__(self):
+        """filtered version of revlog.__iter__"""
+        for i in xrange(len(self)):
+            if i not in self.filteredrevs:
+                yield i
+
+    def irevs(self, start=0, stop=None):
+        """filtered version of revlog.irevs"""
+        for i in super(changelog, self).irevs(start, stop):
+            if i not in self.filteredrevs:
+                yield i
+
+    @util.propertycache
+    def nodemap(self):
+        # XXX need filtering too
+        self.rev(self.node(0))
+        return self._nodecache
+
+    def hasnode(self, node):
+        """filtered version of revlog.hasnode"""
+        try:
+            i = self.rev(node)
+            return i not in self.filteredrevs
+        except KeyError:
+            return False
+
+    def headrevs(self):
+        if self.filteredrevs:
+            # XXX we should fix and use the C version
+            return self._headrevs()
+        return super(changelog, self).headrevs()
+
+    # from there filtered version are not "necessary" but welcome for
+    # consistency
+    #
+    # We should raise a recognisable exception to display useful message in the
+    # ui
+    #
+    # class FilteredIndex(IndexError): pass
+
+    def strip(self, *args, **kwargs):
+        # XXX make something better than assert
+        # We can't expect proper strip behavior if we are filtered.
+        assert not self.filteredrevs
+        super(changelog, self).strip(*args, **kwargs)
+
+    def rev(self, node):
+        """filtered version of revlog.rev"""
+        r = super(changelog, self).rev(node)
+        if r in self.filteredrevs:
+            raise LookupError(node, self.indexfile, _('no node'))
+        return r
+
+    def node(self, rev):
+        """filtered version of revlog.node"""
+        if rev in self.filteredrevs:
+            raise IndexError(rev)
+        return super(changelog, self).node(rev)
+
+    def linkrev(self, rev):
+        """filtered version of revlog.linkrev"""
+        if rev in self.filteredrevs:
+            raise IndexError(rev)
+        return super(changelog, self).linkrev(rev)
+
+    def parentrevs(self, rev):
+        """filtered version of revlog.parentrevs"""
+        if rev in self.filteredrevs:
+            raise IndexError(rev)
+        return super(changelog, self).parentrevs(rev)
+
+    def flags(self, rev):
+        """filtered version of revlog.flags"""
+        if rev in self.filteredrevs:
+            raise IndexError(rev)
+        return super(changelog, self).flags(rev)
 
     def delayupdate(self):
         "delay visibility of index updates to other readers"
         self._delayed = True
         self._divert = (len(self) == 0)