remove unused imports

mercurial/dirstate.py

@@ -1,641 +1,641 b''
 # dirstate.py - working directory tracking for mercurial
 #
 # Copyright 2005-2007 Matt Mackall <[e-mail]>
 #
 # This software may be used and distributed according to the terms of the
 # GNU General Public License version 2, incorporated herein by reference.
 
 from node import nullid
 from i18n import _
 import util, ignore, osutil, parsers
 import struct, os, stat, errno
-import cStringIO, sys
+import cStringIO
 
 _unknown = ('?', 0, 0, 0)
 _format = ">cllll"
 propertycache = util.propertycache
 
 def _finddirs(path):
     pos = path.rfind('/')
     while pos != -1:
         yield path[:pos]
         pos = path.rfind('/', 0, pos)
 
 def _incdirs(dirs, path):
     for base in _finddirs(path):
         if base in dirs:
             dirs[base] += 1
             return
         dirs[base] = 1
 
 def _decdirs(dirs, path):
     for base in _finddirs(path):
         if dirs[base] > 1:
             dirs[base] -= 1
             return
         del dirs[base]
 
 class dirstate(object):
 
     def __init__(self, opener, ui, root):
         '''Create a new dirstate object.  opener is an open()-like callable
         that can be used to open the dirstate file; root is the root of the
         directory tracked by the dirstate.'''
         self._opener = opener
         self._root = root
         self._rootdir = os.path.join(root, '')
         self._dirty = False
         self._dirtypl = False
         self._ui = ui
 
     @propertycache
     def _map(self):
         '''Return the dirstate contents as a map from filename to
         (state, mode, size, time).'''
         self._read()
         return self._map
 
     @propertycache
     def _copymap(self):
         self._read()
         return self._copymap
 
     @propertycache
     def _foldmap(self):
         f = {}
         for name in self._map:
             f[os.path.normcase(name)] = name
         return f
 
     @propertycache
     def _branch(self):
         try:
             return self._opener("branch").read().strip() or "default"
         except IOError:
             return "default"
 
     @propertycache
     def _pl(self):
         try:
             st = self._opener("dirstate").read(40)
             l = len(st)
             if l == 40:
                 return st[:20], st[20:40]
             elif l > 0 and l < 40:
                 raise util.Abort(_('working directory state appears damaged!'))
         except IOError, err:
             if err.errno != errno.ENOENT: raise
         return [nullid, nullid]
 
     @propertycache
     def _dirs(self):
         dirs = {}
         for f,s in self._map.iteritems():
             if s[0] != 'r':
                 _incdirs(dirs, f)
         return dirs
 
     @propertycache
     def _ignore(self):
         files = [self._join('.hgignore')]
         for name, path in self._ui.configitems("ui"):
             if name == 'ignore' or name.startswith('ignore.'):
                 files.append(util.expandpath(path))
         return ignore.ignore(self._root, files, self._ui.warn)
 
     @propertycache
     def _slash(self):
         return self._ui.configbool('ui', 'slash') and os.sep != '/'
 
     @propertycache
     def _checklink(self):
         return util.checklink(self._root)
 
     @propertycache
     def _checkexec(self):
         return util.checkexec(self._root)
 
     @propertycache
     def _checkcase(self):
         return not util.checkcase(self._join('.hg'))
 
     def _join(self, f):
         # much faster than os.path.join()
         # it's safe because f is always a relative path
         return self._rootdir + f
 
     def flagfunc(self, fallback):
         if self._checklink:
             if self._checkexec:
                 def f(x):
                     p = self._join(x)
                     if os.path.islink(p):
                         return 'l'
                     if util.is_exec(p):
                         return 'x'
                     return ''
                 return f
             def f(x):
                 if os.path.islink(self._join(x)):
                     return 'l'
                 if 'x' in fallback(x):
                     return 'x'
                 return ''
             return f
         if self._checkexec:
             def f(x):
                 if 'l' in fallback(x):
                     return 'l'
                 if util.is_exec(self._join(x)):
                     return 'x'
                 return ''
             return f
         return fallback
 
     def getcwd(self):
         cwd = os.getcwd()
         if cwd == self._root: return ''
         # self._root ends with a path separator if self._root is '/' or 'C:\'
         rootsep = self._root
         if not util.endswithsep(rootsep):
             rootsep += os.sep
         if cwd.startswith(rootsep):
             return cwd[len(rootsep):]
         else:
             # we're outside the repo. return an absolute path.
             return cwd
 
     def pathto(self, f, cwd=None):
         if cwd is None:
             cwd = self.getcwd()
         path = util.pathto(self._root, cwd, f)
         if self._slash:
             return util.normpath(path)
         return path
 
     def __getitem__(self, key):
         '''Return the current state of key (a filename) in the dirstate.
         States are:
           n  normal
           m  needs merging
           r  marked for removal
           a  marked for addition
           ?  not tracked
         '''
         return self._map.get(key, ("?",))[0]
 
     def __contains__(self, key):
         return key in self._map
 
     def __iter__(self):
         for x in sorted(self._map):
             yield x
 
     def parents(self):
         return self._pl
 
     def branch(self):
         return self._branch
 
     def setparents(self, p1, p2=nullid):
         self._dirty = self._dirtypl = True
         self._pl = p1, p2
 
     def setbranch(self, branch):
         self._branch = branch
         self._opener("branch", "w").write(branch + '\n')
 
     def _read(self):
         self._map = {}
         self._copymap = {}
         try:
             st = self._opener("dirstate").read()
         except IOError, err:
             if err.errno != errno.ENOENT: raise
             return
         if not st:
             return
 
         p = parsers.parse_dirstate(self._map, self._copymap, st)
         if not self._dirtypl:
             self._pl = p
 
     def invalidate(self):
         for a in "_map _copymap _foldmap _branch _pl _dirs _ignore".split():
             if a in self.__dict__:
                 delattr(self, a)
         self._dirty = False
 
     def copy(self, source, dest):
         """Mark dest as a copy of source. Unmark dest if source is None.
         """
         if source == dest:
             return
         self._dirty = True
         if source is not None:
             self._copymap[dest] = source
         elif dest in self._copymap:
             del self._copymap[dest]
 
     def copied(self, file):
         return self._copymap.get(file, None)
 
     def copies(self):
         return self._copymap
 
     def _droppath(self, f):
         if self[f] not in "?r" and "_dirs" in self.__dict__:
             _decdirs(self._dirs, f)
 
     def _addpath(self, f, check=False):
         oldstate = self[f]
         if check or oldstate == "r":
             if '\r' in f or '\n' in f:
                 raise util.Abort(
                     _("'\\n' and '\\r' disallowed in filenames: %r") % f)
             if f in self._dirs:
                 raise util.Abort(_('directory %r already in dirstate') % f)
             # shadows
             for d in _finddirs(f):
                 if d in self._dirs:
                     break
                 if d in self._map and self[d] != 'r':
                     raise util.Abort(
                         _('file %r in dirstate clashes with %r') % (d, f))
         if oldstate in "?r" and "_dirs" in self.__dict__:
             _incdirs(self._dirs, f)
 
     def normal(self, f):
         'mark a file normal and clean'
         self._dirty = True
         self._addpath(f)
         s = os.lstat(self._join(f))
         self._map[f] = ('n', s.st_mode, s.st_size, int(s.st_mtime))
         if f in self._copymap:
             del self._copymap[f]
 
     def normallookup(self, f):
         'mark a file normal, but possibly dirty'
         if self._pl[1] != nullid and f in self._map:
             # if there is a merge going on and the file was either
             # in state 'm' or dirty before being removed, restore that state.
             entry = self._map[f]
             if entry[0] == 'r' and entry[2] in (-1, -2):
                 source = self._copymap.get(f)
                 if entry[2] == -1:
                     self.merge(f)
                 elif entry[2] == -2:
                     self.normaldirty(f)
                 if source:
                     self.copy(source, f)
                 return
             if entry[0] == 'm' or entry[0] == 'n' and entry[2] == -2:
                 return
         self._dirty = True
         self._addpath(f)
         self._map[f] = ('n', 0, -1, -1)
         if f in self._copymap:
             del self._copymap[f]
 
     def normaldirty(self, f):
         'mark a file normal, but dirty'
         self._dirty = True
         self._addpath(f)
         self._map[f] = ('n', 0, -2, -1)
         if f in self._copymap:
             del self._copymap[f]
 
     def add(self, f):
         'mark a file added'
         self._dirty = True
         self._addpath(f, True)
         self._map[f] = ('a', 0, -1, -1)
         if f in self._copymap:
             del self._copymap[f]
 
     def remove(self, f):
         'mark a file removed'
         self._dirty = True
         self._droppath(f)
         size = 0
         if self._pl[1] != nullid and f in self._map:
             entry = self._map[f]
             if entry[0] == 'm':
                 size = -1
             elif entry[0] == 'n' and entry[2] == -2:
                 size = -2
         self._map[f] = ('r', 0, size, 0)
         if size == 0 and f in self._copymap:
             del self._copymap[f]
 
     def merge(self, f):
         'mark a file merged'
         self._dirty = True
         s = os.lstat(self._join(f))
         self._addpath(f)
         self._map[f] = ('m', s.st_mode, s.st_size, int(s.st_mtime))
         if f in self._copymap:
             del self._copymap[f]
 
     def forget(self, f):
         'forget a file'
         self._dirty = True
         try:
             self._droppath(f)
             del self._map[f]
         except KeyError:
             self._ui.warn(_("not in dirstate: %s\n") % f)
 
     def _normalize(self, path, knownpath):
         norm_path = os.path.normcase(path)
         fold_path = self._foldmap.get(norm_path, None)
         if fold_path is None:
             if knownpath or not os.path.exists(os.path.join(self._root, path)):
                 fold_path = path
             else:
                 fold_path = self._foldmap.setdefault(norm_path,
                                 util.fspath(path, self._root))
         return fold_path
 
     def clear(self):
         self._map = {}
         if "_dirs" in self.__dict__:
             delattr(self, "_dirs");
         self._copymap = {}
         self._pl = [nullid, nullid]
         self._dirty = True
 
     def rebuild(self, parent, files):
         self.clear()
         for f in files:
             if 'x' in files.flags(f):
                 self._map[f] = ('n', 0777, -1, 0)
             else:
                 self._map[f] = ('n', 0666, -1, 0)
         self._pl = (parent, nullid)
         self._dirty = True
 
     def write(self):
         if not self._dirty:
             return
         st = self._opener("dirstate", "w", atomictemp=True)
 
         # use the modification time of the newly created temporary file as the
         # filesystem's notion of 'now'
         now = int(util.fstat(st).st_mtime)
 
         cs = cStringIO.StringIO()
         copymap = self._copymap
         pack = struct.pack
         write = cs.write
         write("".join(self._pl))
         for f, e in self._map.iteritems():
             if f in copymap:
                 f = "%s\0%s" % (f, copymap[f])
 
             if e[0] == 'n' and e[3] == now:
                 # The file was last modified "simultaneously" with the current
                 # write to dirstate (i.e. within the same second for file-
                 # systems with a granularity of 1 sec). This commonly happens
                 # for at least a couple of files on 'update'.
                 # The user could change the file without changing its size
                 # within the same second. Invalidate the file's stat data in
                 # dirstate, forcing future 'status' calls to compare the
                 # contents of the file. This prevents mistakenly treating such
                 # files as clean.
                 e = (e[0], 0, -1, -1)   # mark entry as 'unset'
 
             e = pack(_format, e[0], e[1], e[2], e[3], len(f))
             write(e)
             write(f)
         st.write(cs.getvalue())
         st.rename()
         self._dirty = self._dirtypl = False
 
     def _dirignore(self, f):
         if f == '.':
             return False
         if self._ignore(f):
             return True
         for p in _finddirs(f):
             if self._ignore(p):
                 return True
         return False
 
     def walk(self, match, unknown, ignored):
         '''
         Walk recursively through the directory tree, finding all files
         matched by match.
 
         Return a dict mapping filename to stat-like object (either
         mercurial.osutil.stat instance or return value of os.stat()).
         '''
 
         def fwarn(f, msg):
             self._ui.warn('%s: %s\n' % (self.pathto(f), msg))
             return False
 
         def badtype(mode):
             kind = _('unknown')
             if stat.S_ISCHR(mode): kind = _('character device')
             elif stat.S_ISBLK(mode): kind = _('block device')
             elif stat.S_ISFIFO(mode): kind = _('fifo')
             elif stat.S_ISSOCK(mode): kind = _('socket')
             elif stat.S_ISDIR(mode): kind = _('directory')
             return _('unsupported file type (type is %s)') % kind
 
         ignore = self._ignore
         dirignore = self._dirignore
         if ignored:
             ignore = util.never
             dirignore = util.never
         elif not unknown:
             # if unknown and ignored are False, skip step 2
             ignore = util.always
             dirignore = util.always
 
         matchfn = match.matchfn
         badfn = match.bad
         dmap = self._map
         normpath = util.normpath
         listdir = osutil.listdir
         lstat = os.lstat
         getkind = stat.S_IFMT
         dirkind = stat.S_IFDIR
         regkind = stat.S_IFREG
         lnkkind = stat.S_IFLNK
         join = self._join
         work = []
         wadd = work.append
 
         if self._checkcase:
             normalize = self._normalize
         else:
             normalize = lambda x, y: x
 
         exact = skipstep3 = False
         if matchfn == match.exact: # match.exact
             exact = True
             dirignore = util.always # skip step 2
         elif match.files() and not match.anypats(): # match.match, no patterns
             skipstep3 = True
 
         files = set(match.files())
         if not files or '.' in files:
             files = ['']
         results = {'.hg': None}
 
         # step 1: find all explicit files
         for ff in sorted(files):
             nf = normalize(normpath(ff), False)
             if nf in results:
                 continue
 
             try:
                 st = lstat(join(nf))
                 kind = getkind(st.st_mode)
                 if kind == dirkind:
                     skipstep3 = False
                     if nf in dmap:
                         #file deleted on disk but still in dirstate
                         results[nf] = None
                     match.dir(nf)
                     if not dirignore(nf):
                         wadd(nf)
                 elif kind == regkind or kind == lnkkind:
                     results[nf] = st
                 else:
                     badfn(ff, badtype(kind))
                     if nf in dmap:
                         results[nf] = None
             except OSError, inst:
                 if nf in dmap: # does it exactly match a file?
                     results[nf] = None
                 else: # does it match a directory?
                     prefix = nf + "/"
                     for fn in dmap:
                         if fn.startswith(prefix):
                             match.dir(nf)
                             skipstep3 = False
                             break
                     else:
                         badfn(ff, inst.strerror)
 
         # step 2: visit subdirectories
         while work:
             nd = work.pop()
             skip = None
             if nd == '.':
                 nd = ''
             else:
                 skip = '.hg'
             try:
                 entries = listdir(join(nd), stat=True, skip=skip)
             except OSError, inst:
                 if inst.errno == errno.EACCES:
                     fwarn(nd, inst.strerror)
                     continue
                 raise
             for f, kind, st in entries:
                 nf = normalize(nd and (nd + "/" + f) or f, True)
                 if nf not in results:
                     if kind == dirkind:
                         if not ignore(nf):
                             match.dir(nf)
                             wadd(nf)
                         if nf in dmap and matchfn(nf):
                             results[nf] = None
                     elif kind == regkind or kind == lnkkind:
                         if nf in dmap:
                             if matchfn(nf):
                                 results[nf] = st
                         elif matchfn(nf) and not ignore(nf):
                             results[nf] = st
                     elif nf in dmap and matchfn(nf):
                         results[nf] = None
 
         # step 3: report unseen items in the dmap hash
         if not skipstep3 and not exact:
             visit = sorted([f for f in dmap if f not in results and matchfn(f)])
             for nf, st in zip(visit, util.statfiles([join(i) for i in visit])):
                 if not st is None and not getkind(st.st_mode) in (regkind, lnkkind):
                     st = None
                 results[nf] = st
 
         del results['.hg']
         return results
 
     def status(self, match, ignored, clean, unknown):
         '''Determine the status of the working copy relative to the
         dirstate and return a tuple of lists (unsure, modified, added,
         removed, deleted, unknown, ignored, clean), where:
 
           unsure:
             files that might have been modified since the dirstate was
             written, but need to be read to be sure (size is the same
             but mtime differs)
           modified:
             files that have definitely been modified since the dirstate
             was written (different size or mode)
           added:
             files that have been explicitly added with hg add
           removed:
             files that have been explicitly removed with hg remove
           deleted:
             files that have been deleted through other means ("missing")
           unknown:
             files not in the dirstate that are not ignored
           ignored:
             files not in the dirstate that are ignored
             (by _dirignore())
           clean:
             files that have definitely not been modified since the
             dirstate was written
         '''
         listignored, listclean, listunknown = ignored, clean, unknown
         lookup, modified, added, unknown, ignored = [], [], [], [], []
         removed, deleted, clean = [], [], []
 
         dmap = self._map
         ladd = lookup.append            # aka "unsure"
         madd = modified.append
         aadd = added.append
         uadd = unknown.append
         iadd = ignored.append
         radd = removed.append
         dadd = deleted.append
         cadd = clean.append
 
         for fn, st in self.walk(match, listunknown, listignored).iteritems():
             if fn not in dmap:
                 if (listignored or match.exact(fn)) and self._dirignore(fn):
                     if listignored:
                         iadd(fn)
                 elif listunknown:
                     uadd(fn)
                 continue
 
             state, mode, size, time = dmap[fn]
 
             if not st and state in "nma":
                 dadd(fn)
             elif state == 'n':
                 if (size >= 0 and
                     (size != st.st_size
                      or ((mode ^ st.st_mode) & 0100 and self._checkexec))
                     or size == -2
                     or fn in self._copymap):
                     madd(fn)
                 elif time != int(st.st_mtime):
                     ladd(fn)
                 elif listclean:
                     cadd(fn)
             elif state == 'm':
                 madd(fn)
             elif state == 'a':
                 aadd(fn)
             elif state == 'r':
                 radd(fn)
 
         return (lookup, modified, added, removed, deleted, unknown, ignored,
                 clean)

mercurial/help.py

@@ -1,92 +1,92 b''
 # help.py - help data 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 version 2, incorporated herein by reference.
 
 from i18n import gettext, _
 import sys, os
-import extensions, util
+import extensions
 
 
 def moduledoc(file):
     '''return the top-level python documentation for the given file
 
     Loosely inspired by pydoc.source_synopsis(), but rewritten to handle \'''
     as well as """ and to return the whole text instead of just the synopsis'''
     result = []
 
     line = file.readline()
     while line[:1] == '#' or not line.strip():
         line = file.readline()
         if not line: break
 
     start = line[:3]
     if start == '"""' or start == "'''":
         line = line[3:]
         while line:
             if line.rstrip().endswith(start):
                 line = line.split(start)[0]
                 if line:
                     result.append(line)
                 break
             elif not line:
                 return None # unmatched delimiter
             result.append(line)
             line = file.readline()
     else:
         return None
 
     return ''.join(result)
 
 def listexts(header, exts, maxlength):
     '''return a text listing of the given extensions'''
     if not exts:
         return ''
     result = '\n%s\n\n' % header
     for name, desc in sorted(exts.iteritems()):
         result += ' %-*s %s\n' % (maxlength + 2, ':%s:' % name, desc)
     return result
 
 def extshelp():
     doc = loaddoc('extensions')()
 
     exts, maxlength = extensions.enabled()
     doc += listexts(_('enabled extensions:'), exts, maxlength)
 
     exts, maxlength = extensions.disabled()
     doc += listexts(_('disabled extensions:'), exts, maxlength)
 
     return doc
 
 def loaddoc(topic):
     """Return a delayed loader for help/topic.txt."""
 
     def loader():
         if hasattr(sys, 'frozen'):
             module = sys.executable
         else:
             module = __file__
         base = os.path.dirname(module)
 
         for dir in ('.', '..'):
             docdir = os.path.join(base, dir, 'help')
             if os.path.isdir(docdir):
                 break
 
         path = os.path.join(docdir, topic + ".txt")
         return gettext(open(path).read())
     return loader
 
 helptable = (
     (["dates"], _("Date Formats"), loaddoc('dates')),
     (["patterns"], _("File Name Patterns"), loaddoc('patterns')),
     (['environment', 'env'], _('Environment Variables'), loaddoc('environment')),
     (['revs', 'revisions'], _('Specifying Single Revisions'), loaddoc('revisions')),
     (['mrevs', 'multirevs'], _('Specifying Multiple Revisions'), loaddoc('multirevs')),
     (['diffs'], _('Diff Formats'), loaddoc('diffs')),
     (['templating', 'templates'], _('Template Usage'), loaddoc('templates')),
     (['urls'], _('URL Paths'), loaddoc('urls')),
     (["extensions"], _("Using additional features"), extshelp),
 )

mercurial/tags.py

@@ -1,341 +1,340 b''
 # tags.py - read tag info from local repository
 #
 # Copyright 2009 Matt Mackall <[e-mail]>
 # Copyright 2009 Greg Ward <[e-mail]>
 #
 # This software may be used and distributed according to the terms of the
 # GNU General Public License version 2, incorporated herein by reference.
 
 # Currently this module only deals with reading and caching tags.
 # Eventually, it could take care of updating (adding/removing/moving)
 # tags too.
 
-import os
 from node import nullid, bin, hex, short
 from i18n import _
 import encoding
 import error
 
 def _debugalways(ui, *msg):
     ui.write(*msg)
 
 def _debugconditional(ui, *msg):
     ui.debug(*msg)
 
 def _debugnever(ui, *msg):
     pass
 
 _debug = _debugalways
 _debug = _debugnever
 
 def findglobaltags1(ui, repo, alltags, tagtypes):
     '''Find global tags in repo by reading .hgtags from every head that
     has a distinct version of it.  Updates the dicts alltags, tagtypes
     in place: alltags maps tag name to (node, hist) pair (see _readtags()
     below), and tagtypes maps tag name to tag type ('global' in this
     case).'''
 
     seen = set()
     fctx = None
     ctxs = []                       # list of filectx
     for node in repo.heads():
         try:
             fnode = repo[node].filenode('.hgtags')
         except error.LookupError:
             continue
         if fnode not in seen:
             seen.add(fnode)
             if not fctx:
                 fctx = repo.filectx('.hgtags', fileid=fnode)
             else:
                 fctx = fctx.filectx(fnode)
             ctxs.append(fctx)
 
     # read the tags file from each head, ending with the tip
     for fctx in reversed(ctxs):
         filetags = _readtags(
             ui, repo, fctx.data().splitlines(), fctx)
         _updatetags(filetags, "global", alltags, tagtypes)
 
 def findglobaltags2(ui, repo, alltags, tagtypes):
     '''Same as findglobaltags1(), but with caching.'''
     # This is so we can be lazy and assume alltags contains only global
     # tags when we pass it to _writetagcache().
     assert len(alltags) == len(tagtypes) == 0, \
            "findglobaltags() should be called first"
 
     (heads, tagfnode, cachetags, shouldwrite) = _readtagcache(ui, repo)
     if cachetags is not None:
         assert not shouldwrite
         # XXX is this really 100% correct?  are there oddball special
         # cases where a global tag should outrank a local tag but won't,
         # because cachetags does not contain rank info?
         _updatetags(cachetags, 'global', alltags, tagtypes)
         return
 
     _debug(ui, "reading tags from %d head(s): %s\n"
            % (len(heads), map(short, reversed(heads))))
     seen = set()                    # set of fnode
     fctx = None
     for head in reversed(heads):        # oldest to newest
         assert head in repo.changelog.nodemap, \
                "tag cache returned bogus head %s" % short(head)
 
         fnode = tagfnode.get(head)
         if fnode and fnode not in seen:
             seen.add(fnode)
             if not fctx:
                 fctx = repo.filectx('.hgtags', fileid=fnode)
             else:
                 fctx = fctx.filectx(fnode)
 
             filetags = _readtags(ui, repo, fctx.data().splitlines(), fctx)
             _updatetags(filetags, 'global', alltags, tagtypes)
 
     # and update the cache (if necessary)
     if shouldwrite:
         _writetagcache(ui, repo, heads, tagfnode, alltags)
 
 # Set this to findglobaltags1 to disable tag caching.
 findglobaltags = findglobaltags2
 
 def readlocaltags(ui, repo, alltags, tagtypes):
     '''Read local tags in repo.  Update alltags and tagtypes.'''
     try:
         # localtags is in the local encoding; re-encode to UTF-8 on
         # input for consistency with the rest of this module.
         data = repo.opener("localtags").read()
         filetags = _readtags(
             ui, repo, data.splitlines(), "localtags",
             recode=encoding.fromlocal)
         _updatetags(filetags, "local", alltags, tagtypes)
     except IOError:
         pass
 
 def _readtags(ui, repo, lines, fn, recode=None):
     '''Read tag definitions from a file (or any source of lines).
     Return a mapping from tag name to (node, hist): node is the node id
     from the last line read for that name, and hist is the list of node
     ids previously associated with it (in file order).  All node ids are
     binary, not hex.'''
 
     filetags = {}               # map tag name to (node, hist)
     count = 0
 
     def warn(msg):
         ui.warn(_("%s, line %s: %s\n") % (fn, count, msg))
 
     for line in lines:
         count += 1
         if not line:
             continue
         try:
             (nodehex, name) = line.split(" ", 1)
         except ValueError:
             warn(_("cannot parse entry"))
             continue
         name = name.strip()
         if recode:
             name = recode(name)
         try:
             nodebin = bin(nodehex)
         except TypeError:
             warn(_("node '%s' is not well formed") % nodehex)
             continue
         if nodebin not in repo.changelog.nodemap:
             # silently ignore as pull -r might cause this
             continue
 
         # update filetags
         hist = []
         if name in filetags:
             n, hist = filetags[name]
             hist.append(n)
         filetags[name] = (nodebin, hist)
     return filetags
 
 def _updatetags(filetags, tagtype, alltags, tagtypes):
     '''Incorporate the tag info read from one file into the two
     dictionaries, alltags and tagtypes, that contain all tag
     info (global across all heads plus local).'''
 
     for name, nodehist in filetags.iteritems():
         if name not in alltags:
             alltags[name] = nodehist
             tagtypes[name] = tagtype
             continue
 
         # we prefer alltags[name] if:
         #  it supercedes us OR
         #  mutual supercedes and it has a higher rank
         # otherwise we win because we're tip-most
         anode, ahist = nodehist
         bnode, bhist = alltags[name]
         if (bnode != anode and anode in bhist and
             (bnode not in ahist or len(bhist) > len(ahist))):
             anode = bnode
         ahist.extend([n for n in bhist if n not in ahist])
         alltags[name] = anode, ahist
         tagtypes[name] = tagtype
 
 
 # The tag cache only stores info about heads, not the tag contents
 # from each head.  I.e. it doesn't try to squeeze out the maximum
 # performance, but is simpler has a better chance of actually
 # working correctly.  And this gives the biggest performance win: it
 # avoids looking up .hgtags in the manifest for every head, and it
 # can avoid calling heads() at all if there have been no changes to
 # the repo.
 
 def _readtagcache(ui, repo):
     '''Read the tag cache and return a tuple (heads, fnodes, cachetags,
     shouldwrite).  If the cache is completely up-to-date, cachetags is a
     dict of the form returned by _readtags(); otherwise, it is None and
     heads and fnodes are set.  In that case, heads is the list of all
     heads currently in the repository (ordered from tip to oldest) and
     fnodes is a mapping from head to .hgtags filenode.  If those two are
     set, caller is responsible for reading tag info from each head.'''
 
     try:
         cachefile = repo.opener('tags.cache', 'r')
         _debug(ui, 'reading tag cache from %s\n' % cachefile.name)
     except IOError:
         cachefile = None
 
     # The cache file consists of lines like
     #   <headrev> <headnode> [<tagnode>]
     # where <headrev> and <headnode> redundantly identify a repository
     # head from the time the cache was written, and <tagnode> is the
     # filenode of .hgtags on that head.  Heads with no .hgtags file will
     # have no <tagnode>.  The cache is ordered from tip to oldest (which
     # is part of why <headrev> is there: a quick visual check is all
     # that's required to ensure correct order).
     #
     # This information is enough to let us avoid the most expensive part
     # of finding global tags, which is looking up <tagnode> in the
     # manifest for each head.
     cacherevs = []                      # list of headrev
     cacheheads = []                     # list of headnode
     cachefnode = {}                     # map headnode to filenode
     if cachefile:
         for line in cachefile:
             if line == "\n":
                 break
             line = line.rstrip().split()
             cacherevs.append(int(line[0]))
             headnode = bin(line[1])
             cacheheads.append(headnode)
             if len(line) == 3:
                 fnode = bin(line[2])
                 cachefnode[headnode] = fnode
 
     tipnode = repo.changelog.tip()
     tiprev = len(repo.changelog) - 1
 
     # Case 1 (common): tip is the same, so nothing has changed.
     # (Unchanged tip trivially means no changesets have been added.
     # But, thanks to localrepository.destroyed(), it also means none
     # have been destroyed by strip or rollback.)
     if cacheheads and cacheheads[0] == tipnode and cacherevs[0] == tiprev:
         _debug(ui, "tag cache: tip unchanged\n")
         tags = _readtags(ui, repo, cachefile, cachefile.name)
         cachefile.close()
         return (None, None, tags, False)
     if cachefile:
         cachefile.close()               # ignore rest of file
 
     repoheads = repo.heads()
     # Case 2 (uncommon): empty repo; get out quickly and don't bother
     # writing an empty cache.
     if repoheads == [nullid]:
         return ([], {}, {}, False)
 
     # Case 3 (uncommon): cache file missing or empty.
     if not cacheheads:
         _debug(ui, 'tag cache: cache file missing or empty\n')
 
     # Case 4 (uncommon): tip rev decreased.  This should only happen
     # when we're called from localrepository.destroyed().  Refresh the
     # cache so future invocations will not see disappeared heads in the
     # cache.
     elif cacheheads and tiprev < cacherevs[0]:
         _debug(ui,
                'tag cache: tip rev decremented (from %d to %d), '
                'so we must be destroying nodes\n'
                % (cacherevs[0], tiprev))
 
     # Case 5 (common): tip has changed, so we've added/replaced heads.
     else:
         _debug(ui,
                'tag cache: tip has changed (%d:%s); must find new heads\n'
                % (tiprev, short(tipnode)))
 
     # Luckily, the code to handle cases 3, 4, 5 is the same.  So the
     # above if/elif/else can disappear once we're confident this thing
     # actually works and we don't need the debug output.
 
     # N.B. in case 4 (nodes destroyed), "new head" really means "newly
     # exposed".
     newheads = [head
                 for head in repoheads
                 if head not in set(cacheheads)]
     _debug(ui, 'tag cache: found %d head(s) not in cache: %s\n'
            % (len(newheads), map(short, newheads)))
 
     # Now we have to lookup the .hgtags filenode for every new head.
     # This is the most expensive part of finding tags, so performance
     # depends primarily on the size of newheads.  Worst case: no cache
     # file, so newheads == repoheads.
     for head in newheads:
         cctx = repo[head]
         try:
             fnode = cctx.filenode('.hgtags')
             cachefnode[head] = fnode
         except error.LookupError:
             # no .hgtags file on this head
             pass
 
     # Caller has to iterate over all heads, but can use the filenodes in
     # cachefnode to get to each .hgtags revision quickly.
     return (repoheads, cachefnode, None, True)
 
 def _writetagcache(ui, repo, heads, tagfnode, cachetags):
 
     try:
         cachefile = repo.opener('tags.cache', 'w', atomictemp=True)
     except (OSError, IOError):
         return
     _debug(ui, 'writing cache file %s\n' % cachefile.name)
 
     realheads = repo.heads()            # for sanity checks below
     for head in heads:
         # temporary sanity checks; these can probably be removed
         # once this code has been in crew for a few weeks
         assert head in repo.changelog.nodemap, \
                'trying to write non-existent node %s to tag cache' % short(head)
         assert head in realheads, \
                'trying to write non-head %s to tag cache' % short(head)
         assert head != nullid, \
                'trying to write nullid to tag cache'
 
         # This can't fail because of the first assert above.  When/if we
         # remove that assert, we might want to catch LookupError here
         # and downgrade it to a warning.
         rev = repo.changelog.rev(head)
 
         fnode = tagfnode.get(head)
         if fnode:
             cachefile.write('%d %s %s\n' % (rev, hex(head), hex(fnode)))
         else:
             cachefile.write('%d %s\n' % (rev, hex(head)))
 
     # Tag names in the cache are in UTF-8 -- which is the whole reason
     # we keep them in UTF-8 throughout this module.  If we converted
     # them local encoding on input, we would lose info writing them to
     # the cache.
     cachefile.write('\n')
     for (name, (node, hist)) in cachetags.iteritems():
         cachefile.write("%s %s\n" % (hex(node), name))
 
     cachefile.rename()
     cachefile.close()