Make filectx lazier - some users never use filenode

mercurial/context.py

@@ -1,186 +1,187
 # context.py - changeset and file context objects for mercurial
 #
 # Copyright 2006 Matt Mackall <[e-mail]>
 #
 # This software may be used and distributed according to the terms
 # of the GNU General Public License, incorporated herein by reference.
 
 from node import *
 from demandload import demandload
 demandload(globals(), "ancestor")
 
 class changectx(object):
     """A changecontext object makes access to data related to a particular
     changeset convenient."""
     def __init__(self, repo, changeid=None):
         """changeid is a revision number, node, or tag"""
         self._repo = repo
 
         if not changeid and changeid != 0:
             p1, p2 = self._repo.dirstate.parents()
             self._rev = self._repo.changelog.rev(p1)
             if self._rev == -1:
                 changeid = 'tip'
             else:
                 self._node = p1
                 return
 
         self._node = self._repo.lookup(changeid)
         self._rev = self._repo.changelog.rev(self._node)
 
     def changeset(self):
         try:
             return self._changeset
         except AttributeError:
             self._changeset = self._repo.changelog.read(self.node())
             return self._changeset
 
     def manifest(self):
         try:
             return self._manifest
         except AttributeError:
             self._manifest = self._repo.manifest.read(self.changeset()[0])
             return self._manifest
 
     def rev(self): return self._rev
     def node(self): return self._node
     def user(self): return self.changeset()[1]
     def date(self): return self.changeset()[2]
     def files(self): return self.changeset()[3]
     def description(self): return self.changeset()[4]
 
     def parents(self):
         """return contexts for each parent changeset"""
         p = self._repo.changelog.parents(self._node)
         return [ changectx(self._repo, x) for x in p ]
 
     def children(self):
         """return contexts for each child changeset"""
         c = self._repo.changelog.children(self._node)
         return [ changectx(self._repo, x) for x in c ]
 
     def filenode(self, path):
         node, flag = self._repo.manifest.find(self.changeset()[0], path)
         return node
 
     def filectx(self, path, fileid=None):
         """get a file context from this changeset"""
         if fileid is None:
             fileid = self.filenode(path)
         return filectx(self._repo, path, fileid=fileid)
 
     def filectxs(self):
         """generate a file context for each file in this changeset's
            manifest"""
         mf = self.manifest()
         m = mf.keys()
         m.sort()
         for f in m:
             yield self.filectx(f, fileid=mf[f])
 
     def ancestor(self, c2):
         """
         return the ancestor context of self and c2
         """
         n = self._repo.changelog.ancestor(self._node, c2._node)
         return changectx(self._repo, n)
 
 class filectx(object):
     """A filecontext object makes access to data related to a particular
        filerevision convenient."""
     def __init__(self, repo, path, changeid=None, fileid=None, filelog=None):
         """changeid can be a changeset revision, node, or tag.
            fileid can be a file revision or node."""
         self._repo = repo
         self._path = path
 
         assert changeid is not None or fileid is not None
 
         if filelog:
             self._filelog = filelog
         else:
             self._filelog = self._repo.file(self._path)
 
         if fileid is None:
-            # if given a changeset id, go ahead and look up the file
             self._changeid = changeid
-            self._changectx = self.changectx()
-            self._filenode = self._changectx.filenode(self._path)
         else:
-            # else delay changectx creation
             self._filenode = self._filelog.lookup(fileid)
             self._changeid = self._filelog.linkrev(self._filenode)
-        self._filerev = self._filelog.rev(self._filenode)
 
-    def changectx(self):
-        try:
-            return self._changectx
-        except AttributeError:
+    def __getattr__(self, name):
+        if name == '_changectx':
             self._changectx = changectx(self._repo, self._changeid)
             return self._changectx
+        elif name == '_filenode':
+            self._filenode = self._changectx.filenode(self._path)
+            return self._filenode
+        elif name == '_filerev':
+            self._filerev = self._filelog.rev(self._filenode)
+            return self._filerev
+        else:
+            raise AttributeError, name
 
     def filerev(self): return self._filerev
     def filenode(self): return self._filenode
     def filelog(self): return self._filelog
 
-    def rev(self): return self.changectx().rev()
-    def node(self): return self.changectx().node()
-    def user(self): return self.changectx().user()
-    def date(self): return self.changectx().date()
-    def files(self): return self.changectx().files()
-    def description(self): return self.changectx().description()
-    def manifest(self): return self.changectx().manifest()
+    def rev(self): return self._changectx.rev()
+    def node(self): return self._changectx.node()
+    def user(self): return self._changectx.user()
+    def date(self): return self._changectx.date()
+    def files(self): return self._changectx.files()
+    def description(self): return self._changectx.description()
+    def manifest(self): return self._changectx.manifest()
 
     def data(self): return self._filelog.read(self._filenode)
     def renamed(self): return self._filelog.renamed(self._filenode)
     def path(self): return self._path
 
     def parents(self):
         p = self._path
         fl = self._filelog
         pl = [ (p, n, fl) for n in self._filelog.parents(self._filenode) ]
 
         r = self.renamed()
         if r:
             pl[0] = (r[0], r[1], None)
 
         return [ filectx(self._repo, p, fileid=n, filelog=l)
                  for p,n,l in pl if n != nullid ]
 
     def children(self):
         # hard for renames
         c = self._filelog.children(self._filenode)
         return [ filectx(self._repo, self._path, fileid=x,
                          filelog=self._filelog) for x in c ]
 
     def annotate(self):
         return self._filelog.annotate(self._filenode)
 
     def ancestor(self, fc2):
         """
         find the common ancestor file context, if any, of self, and fc2
         """
 
         acache = {}
         flcache = {self._path:self._filelog, fc2._path:fc2._filelog}
         def parents(vertex):
             if vertex in acache:
                 return acache[vertex]
             f, n = vertex
             if f not in flcache:
                 flcache[f] = self._repo.file(f)
             fl = flcache[f]
             pl = [ (f,p) for p in fl.parents(n) if p != nullid ]
             re = fl.renamed(n)
             if re:
                 pl.append(re)
             acache[vertex]=pl
             return pl
 
         a, b = (self._path, self._filenode), (fc2._path, fc2._filenode)
         v = ancestor.ancestor(a, b, parents)
         if v:
             f,n = v
             return filectx(self._repo, f, fileid=n, filelog=flcache[f])
 
         return None