text: # revset.py - revision set queries for mercurial
  #
  # Copyright 2010 Matt Mackall <mpm@selenic.com>
  #
  # This software may be used and distributed according to the terms of the
  # GNU General Public License version 2 or any later version.
  
  import re
  import parser, util, error, hbisect, phases
  import node
  import heapq
  import match as matchmod
  from i18n import _
  import encoding
  import obsolete as obsmod
  import pathutil
  import repoview
  
  def _revancestors(repo, revs, followfirst):
      """Like revlog.ancestors(), but supports followfirst."""
      if followfirst:
          cut = 1
      else:
          cut = None
      cl = repo.changelog
  
      def iterate():
          revqueue, revsnode = None, None
          h = []
  
          revs.sort(reverse=True)
          revqueue = util.deque(revs)
          if revqueue:
              revsnode = revqueue.popleft()
              heapq.heappush(h, -revsnode)
  
          seen = set()
          while h:
              current = -heapq.heappop(h)
              if current not in seen:
                  if revsnode and current == revsnode:
                      if revqueue:
                          revsnode = revqueue.popleft()
                          heapq.heappush(h, -revsnode)
                  seen.add(current)
                  yield current
                  for parent in cl.parentrevs(current)[:cut]:
                      if parent != node.nullrev:
                          heapq.heappush(h, -parent)
  
      return generatorset(iterate(), iterasc=False)
  
  def _revdescendants(repo, revs, followfirst):
      """Like revlog.descendants() but supports followfirst."""
      if followfirst:
          cut = 1
      else:
          cut = None
  
      def iterate():
          cl = repo.changelog
          first = min(revs)
          nullrev = node.nullrev
          if first == nullrev:
              # Are there nodes with a null first parent and a non-null
              # second one? Maybe. Do we care? Probably not.
              for i in cl:
                  yield i
          else:
              seen = set(revs)
              for i in cl.revs(first + 1):
                  for x in cl.parentrevs(i)[:cut]:
                      if x != nullrev and x in seen:
                          seen.add(i)
                          yield i
                          break
  
      return generatorset(iterate(), iterasc=True)
  
  def _revsbetween(repo, roots, heads):
      """Return all paths between roots and heads, inclusive of both endpoint
      sets."""
      if not roots:
          return baseset()
      parentrevs = repo.changelog.parentrevs
      visit = list(heads)
      reachable = set()
      seen = {}
      minroot = min(roots)
      roots = set(roots)
      # open-code the post-order traversal due to the tiny size of
      # sys.getrecursionlimit()
      while visit:
          rev = visit.pop()
          if rev in roots:
              reachable.add(rev)
          parents = parentrevs(rev)
          seen[rev] = parents
          for parent in parents:
              if parent >= minroot and parent not in seen:
                  visit.append(parent)
      if not reachable:
          return baseset()
      for rev in sorted(seen):
          for parent in seen[rev]:
              if parent in reachable:
                  reachable.add(rev)
      return baseset(sorted(reachable))
  
  elements = {
      "(": (21, ("group", 1, ")"), ("func", 1, ")")),
      "##": (20, None, ("_concat", 20)),
      "~": (18, None, ("ancestor", 18)),
      "^": (18, None, ("parent", 18), ("parentpost", 18)),
      "-": (5, ("negate", 19), ("minus", 5)),
      "::": (17, ("dagrangepre", 17), ("dagrange", 17),
             ("dagrangepost", 17)),
      "..": (17, ("dagrangepre", 17), ("dagrange", 17),
             ("dagrangepost", 17)),
      ":": (15, ("rangepre", 15), ("range", 15), ("rangepost", 15)),
      "not": (10, ("not", 10)),
      "!": (10, ("not", 10)),
      "and": (5, None, ("and", 5)),
      "&": (5, None, ("and", 5)),
      "%": (5, None, ("only", 5), ("onlypost", 5)),
      "or": (4, None, ("or", 4)),
      "|": (4, None, ("or", 4)),
      "+": (4, None, ("or", 4)),
      ",": (2, None, ("list", 2)),
      ")": (0, None, None),
      "symbol": (0, ("symbol",), None),
      "string": (0, ("string",), None),
      "end": (0, None, None),
  }
  
  keywords = set(['and', 'or', 'not'])
  
  # default set of valid characters for the initial letter of symbols
  _syminitletters = set(c for c in [chr(i) for i in xrange(256)]
                        if c.isalnum() or c in '._@' or ord(c) > 127)
  
  # default set of valid characters for non-initial letters of symbols
  _symletters = set(c for c in  [chr(i) for i in xrange(256)]
                    if c.isalnum() or c in '-._/@' or ord(c) > 127)
  
  def tokenize(program, lookup=None, syminitletters=None, symletters=None):
      '''
      Parse a revset statement into a stream of tokens
  
      ``syminitletters`` is the set of valid characters for the initial
      letter of symbols.
  
      By default, character ``c`` is recognized as valid for initial
      letter of symbols, if ``c.isalnum() or c in '._@' or ord(c) > 127``.
  
      ``symletters`` is the set of valid characters for non-initial
      letters of symbols.
  
      By default, character ``c`` is recognized as valid for non-initial
      letters of symbols, if ``c.isalnum() or c in '-._/@' or ord(c) > 127``.
  
      Check that @ is a valid unquoted token character (issue3686):
      >>> list(tokenize("@::"))
      [('symbol', '@', 0), ('::', None, 1), ('end', None, 3)]
  
      '''
      if syminitletters is None:
          syminitletters = _syminitletters
      if symletters is None:
          symletters = _symletters
  
      pos, l = 0, len(program)
      while pos < l:
          c = program[pos]
          if c.isspace(): # skip inter-token whitespace
              pass
          elif c == ':' and program[pos:pos + 2] == '::': # look ahead carefully
              yield ('::', None, pos)
              pos += 1 # skip ahead
          elif c == '.' and program[pos:pos + 2] == '..': # look ahead carefully
              yield ('..', None, pos)
              pos += 1 # skip ahead
          elif c == '#' and program[pos:pos + 2] == '##': # look ahead carefully
              yield ('##', None, pos)
              pos += 1 # skip ahead
          elif c in "():,-|&+!~^%": # handle simple operators
              yield (c, None, pos)
          elif (c in '"\'' or c == 'r' and
                program[pos:pos + 2] in ("r'", 'r"')): # handle quoted strings
              if c == 'r':
                  pos += 1
                  c = program[pos]
                  decode = lambda x: x
              else:
                  decode = lambda x: x.decode('string-escape')
              pos += 1
              s = pos
              while pos < l: # find closing quote
                  d = program[pos]
                  if d == '\\': # skip over escaped characters
                      pos += 2
                      continue
                  if d == c:
                      yield ('string', decode(program[s:pos]), s)
                      break
                  pos += 1
              else:
                  raise error.ParseError(_("unterminated string"), s)
          # gather up a symbol/keyword
          elif c in syminitletters:
              s = pos
              pos += 1
              while pos < l: # find end of symbol
                  d = program[pos]
                  if d not in symletters:
                      break
                  if d == '.' and program[pos - 1] == '.': # special case for ..
                      pos -= 1
                      break
                  pos += 1
              sym = program[s:pos]
              if sym in keywords: # operator keywords
                  yield (sym, None, s)
              elif '-' in sym:
                  # some jerk gave us foo-bar-baz, try to check if it's a symbol
                  if lookup and lookup(sym):
                      # looks like a real symbol
                      yield ('symbol', sym, s)
                  else:
                      # looks like an expression
                      parts = sym.split('-')
                      for p in parts[:-1]:
                          if p: # possible consecutive -
                              yield ('symbol', p, s)
                          s += len(p)
                          yield ('-', None, pos)
                          s += 1
                      if parts[-1]: # possible trailing -
                          yield ('symbol', parts[-1], s)
              else:
                  yield ('symbol', sym, s)
              pos -= 1
          else:
              raise error.ParseError(_("syntax error in revset '%s'") %
                                     program, pos)
          pos += 1
      yield ('end', None, pos)
  
  def parseerrordetail(inst):
      """Compose error message from specified ParseError object
      """
      if len(inst.args) > 1:
          return _('at %s: %s') % (inst.args[1], inst.args[0])
      else:
          return inst.args[0]
  
  # helpers
  
  def getstring(x, err):
      if x and (x[0] == 'string' or x[0] == 'symbol'):
          return x[1]
      raise error.ParseError(err)
  
  def getlist(x):
      if not x:
          return []
      if x[0] == 'list':
          return getlist(x[1]) + [x[2]]
      return [x]
  
  def getargs(x, min, max, err):
      l = getlist(x)
      if len(l) < min or (max >= 0 and len(l) > max):
          raise error.ParseError(err)
      return l
  
  def isvalidsymbol(tree):
      """Examine whether specified ``tree`` is valid ``symbol`` or not
      """
      return tree[0] == 'symbol' and len(tree) > 1
  
  def getsymbol(tree):
      """Get symbol name from valid ``symbol`` in ``tree``
  
      This assumes that ``tree`` is already examined by ``isvalidsymbol``.
      """
      return tree[1]
  
  def isvalidfunc(tree):
      """Examine whether specified ``tree`` is valid ``func`` or not
      """
      return tree[0] == 'func' and len(tree) > 1 and isvalidsymbol(tree[1])
  
  def getfuncname(tree):
      """Get function name from valid ``func`` in ``tree``
  
      This assumes that ``tree`` is already examined by ``isvalidfunc``.
      """
      return getsymbol(tree[1])
  
  def getfuncargs(tree):
      """Get list of function arguments from valid ``func`` in ``tree``
  
      This assumes that ``tree`` is already examined by ``isvalidfunc``.
      """
      if len(tree) > 2:
          return getlist(tree[2])
      else:
          return []
  
  def getset(repo, subset, x):
      if not x:
          raise error.ParseError(_("missing argument"))
      s = methods[x[0]](repo, subset, *x[1:])
      if util.safehasattr(s, 'isascending'):
          return s
      return baseset(s)
  
  def _getrevsource(repo, r):
      extra = repo[r].extra()
      for label in ('source', 'transplant_source', 'rebase_source'):
          if label in extra:
              try:
                  return repo[extra[label]].rev()
              except error.RepoLookupError:
                  pass
      return None
  
  # operator methods
  
  def stringset(repo, subset, x):
      x = repo[x].rev()
      if (x in subset
          or x == node.nullrev and isinstance(subset, fullreposet)):
          return baseset([x])
      return baseset()
  
  def symbolset(repo, subset, x):
      if x in symbols:
          raise error.ParseError(_("can't use %s here") % x)
      return stringset(repo, subset, x)
  
  def rangeset(repo, subset, x, y):
      m = getset(repo, fullreposet(repo), x)
      n = getset(repo, fullreposet(repo), y)
  
      if not m or not n:
          return baseset()
      m, n = m.first(), n.last()
  
      if m < n:
          r = spanset(repo, m, n + 1)
      else:
          r = spanset(repo, m, n - 1)
      return r & subset
  
  def dagrange(repo, subset, x, y):
      r = fullreposet(repo)
      xs = _revsbetween(repo, getset(repo, r, x), getset(repo, r, y))
      return xs & subset
  
  def andset(repo, subset, x, y):
      return getset(repo, getset(repo, subset, x), y)
  
  def orset(repo, subset, x, y):
      xl = getset(repo, subset, x)
      yl = getset(repo, subset - xl, y)
      return xl + yl
  
  def notset(repo, subset, x):
      return subset - getset(repo, subset, x)
  
  def listset(repo, subset, a, b):
      raise error.ParseError(_("can't use a list in this context"))
  
  def func(repo, subset, a, b):
      if a[0] == 'symbol' and a[1] in symbols:
          return symbols[a[1]](repo, subset, b)
      raise error.UnknownIdentifier(a[1], symbols.keys())
  
  # functions
  
  def adds(repo, subset, x):
      """``adds(pattern)``
      Changesets that add a file matching pattern.
  
      The pattern without explicit kind like ``glob:`` is expected to be
      relative to the current directory and match against a file or a
      directory.
      """
      # i18n: "adds" is a keyword
      pat = getstring(x, _("adds requires a pattern"))
      return checkstatus(repo, subset, pat, 1)
  
  def ancestor(repo, subset, x):
      """``ancestor(*changeset)``
      A greatest common ancestor of the changesets.
  
      Accepts 0 or more changesets.
      Will return empty list when passed no args.
      Greatest common ancestor of a single changeset is that changeset.
      """
      # i18n: "ancestor" is a keyword
      l = getlist(x)
      rl = fullreposet(repo)
      anc = None
  
      # (getset(repo, rl, i) for i in l) generates a list of lists
      for revs in (getset(repo, rl, i) for i in l):
          for r in revs:
              if anc is None:
                  anc = repo[r]
              else:
                  anc = anc.ancestor(repo[r])
  
      if anc is not None and anc.rev() in subset:
          return baseset([anc.rev()])
      return baseset()
  
  def _ancestors(repo, subset, x, followfirst=False):
      heads = getset(repo, fullreposet(repo), x)
      if not heads:
          return baseset()
      s = _revancestors(repo, heads, followfirst)
      return subset & s
  
  def ancestors(repo, subset, x):
      """``ancestors(set)``
      Changesets that are ancestors of a changeset in set.
      """
      return _ancestors(repo, subset, x)
  
  def _firstancestors(repo, subset, x):
      # ``_firstancestors(set)``
      # Like ``ancestors(set)`` but follows only the first parents.
      return _ancestors(repo, subset, x, followfirst=True)
  
  def ancestorspec(repo, subset, x, n):
      """``set~n``
      Changesets that are the Nth ancestor (first parents only) of a changeset
      in set.
      """
      try:
          n = int(n[1])
      except (TypeError, ValueError):
          raise error.ParseError(_("~ expects a number"))
      ps = set()
      cl = repo.changelog
      for r in getset(repo, fullreposet(repo), x):
          for i in range(n):
              r = cl.parentrevs(r)[0]
          ps.add(r)
      return subset & ps
  
  def author(repo, subset, x):
      """``author(string)``
      Alias for ``user(string)``.
      """
      # i18n: "author" is a keyword
      n = encoding.lower(getstring(x, _("author requires a string")))
      kind, pattern, matcher = _substringmatcher(n)
      return subset.filter(lambda x: matcher(encoding.lower(repo[x].user())))
  
  def bisect(repo, subset, x):
      """``bisect(string)``
      Changesets marked in the specified bisect status:
  
      - ``good``, ``bad``, ``skip``: csets explicitly marked as good/bad/skip
      - ``goods``, ``bads``      : csets topologically good/bad
      - ``range``              : csets taking part in the bisection
      - ``pruned``             : csets that are goods, bads or skipped
      - ``untested``           : csets whose fate is yet unknown
      - ``ignored``            : csets ignored due to DAG topology
      - ``current``            : the cset currently being bisected
      """
      # i18n: "bisect" is a keyword
      status = getstring(x, _("bisect requires a string")).lower()
      state = set(hbisect.get(repo, status))
      return subset & state
  
  # Backward-compatibility
  # - no help entry so that we do not advertise it any more
  def bisected(repo, subset, x):
      return bisect(repo, subset, x)
  
  def bookmark(repo, subset, x):
      """``bookmark([name])``
      The named bookmark or all bookmarks.
  
      If `name` starts with `re:`, the remainder of the name is treated as
      a regular expression. To match a bookmark that actually starts with `re:`,
      use the prefix `literal:`.
      """
      # i18n: "bookmark" is a keyword
      args = getargs(x, 0, 1, _('bookmark takes one or no arguments'))
      if args:
          bm = getstring(args[0],
                         # i18n: "bookmark" is a keyword
                         _('the argument to bookmark must be a string'))
          kind, pattern, matcher = _stringmatcher(bm)
          bms = set()
          if kind == 'literal':
              bmrev = repo._bookmarks.get(pattern, None)
              if not bmrev:
                  raise error.RepoLookupError(_("bookmark '%s' does not exist")
                                              % bm)
              bms.add(repo[bmrev].rev())
          else:
              matchrevs = set()
              for name, bmrev in repo._bookmarks.iteritems():
                  if matcher(name):
                      matchrevs.add(bmrev)
              if not matchrevs:
                  raise error.RepoLookupError(_("no bookmarks exist"
                                                " that match '%s'") % pattern)
              for bmrev in matchrevs:
                  bms.add(repo[bmrev].rev())
      else:
          bms = set([repo[r].rev()
                     for r in repo._bookmarks.values()])
      bms -= set([node.nullrev])
      return subset & bms
  
  def branch(repo, subset, x):
      """``branch(string or set)``
      All changesets belonging to the given branch or the branches of the given
      changesets.
  
      If `string` starts with `re:`, the remainder of the name is treated as
      a regular expression. To match a branch that actually starts with `re:`,
      use the prefix `literal:`.
      """
      getbi = repo.revbranchcache().branchinfo
  
      try:
          b = getstring(x, '')
      except error.ParseError:
          # not a string, but another revspec, e.g. tip()
          pass
      else:
          kind, pattern, matcher = _stringmatcher(b)
          if kind == 'literal':
              # note: falls through to the revspec case if no branch with
              # this name exists
              if pattern in repo.branchmap():
                  return subset.filter(lambda r: matcher(getbi(r)[0]))
          else:
              return subset.filter(lambda r: matcher(getbi(r)[0]))
  
      s = getset(repo, fullreposet(repo), x)
      b = set()
      for r in s:
          b.add(getbi(r)[0])
      c = s.__contains__
      return subset.filter(lambda r: c(r) or getbi(r)[0] in b)
  
  def bumped(repo, subset, x):
      """``bumped()``
      Mutable changesets marked as successors of public changesets.
  
      Only non-public and non-obsolete changesets can be `bumped`.
      """
      # i18n: "bumped" is a keyword
      getargs(x, 0, 0, _("bumped takes no arguments"))
      bumped = obsmod.getrevs(repo, 'bumped')
      return subset & bumped
  
  def bundle(repo, subset, x):
      """``bundle()``
      Changesets in the bundle.
  
      Bundle must be specified by the -R option."""
  
      try:
          bundlerevs = repo.changelog.bundlerevs
      except AttributeError:
          raise util.Abort(_("no bundle provided - specify with -R"))
      return subset & bundlerevs
  
  def checkstatus(repo, subset, pat, field):
      hasset = matchmod.patkind(pat) == 'set'
  
      mcache = [None]
      def matches(x):
          c = repo[x]
          if not mcache[0] or hasset:
              mcache[0] = matchmod.match(repo.root, repo.getcwd(), [pat], ctx=c)
          m = mcache[0]
          fname = None
          if not m.anypats() and len(m.files()) == 1:
              fname = m.files()[0]
          if fname is not None:
              if fname not in c.files():
                  return False
          else:
              for f in c.files():
                  if m(f):
                      break
              else:
                  return False
          files = repo.status(c.p1().node(), c.node())[field]
          if fname is not None:
              if fname in files:
                  return True
          else:
              for f in files:
                  if m(f):
                      return True
  
      return subset.filter(matches)
  
  def _children(repo, narrow, parentset):
      cs = set()
      if not parentset:
          return baseset(cs)
      pr = repo.changelog.parentrevs
      minrev = min(parentset)
      for r in narrow:
          if r <= minrev:
              continue
          for p in pr(r):
              if p in parentset:
                  cs.add(r)
      return baseset(cs)
  
  def children(repo, subset, x):
      """``children(set)``
      Child changesets of changesets in set.
      """
      s = getset(repo, fullreposet(repo), x)
      cs = _children(repo, subset, s)
      return subset & cs
  
  def closed(repo, subset, x):
      """``closed()``
      Changeset is closed.
      """
      # i18n: "closed" is a keyword
      getargs(x, 0, 0, _("closed takes no arguments"))
      return subset.filter(lambda r: repo[r].closesbranch())
  
  def contains(repo, subset, x):
      """``contains(pattern)``
      The revision's manifest contains a file matching pattern (but might not
      modify it). See :hg:`help patterns` for information about file patterns.
  
      The pattern without explicit kind like ``glob:`` is expected to be
      relative to the current directory and match against a file exactly
      for efficiency.
      """
      # i18n: "contains" is a keyword
      pat = getstring(x, _("contains requires a pattern"))
  
      def matches(x):
          if not matchmod.patkind(pat):
              pats = pathutil.canonpath(repo.root, repo.getcwd(), pat)
              if pats in repo[x]:
                  return True
          else:
              c = repo[x]
              m = matchmod.match(repo.root, repo.getcwd(), [pat], ctx=c)
              for f in c.manifest():
                  if m(f):
                      return True
          return False
  
      return subset.filter(matches)
  
  def converted(repo, subset, x):
      """``converted([id])``
      Changesets converted from the given identifier in the old repository if
      present, or all converted changesets if no identifier is specified.
      """
  
      # There is exactly no chance of resolving the revision, so do a simple
      # string compare and hope for the best
  
      rev = None
      # i18n: "converted" is a keyword
      l = getargs(x, 0, 1, _('converted takes one or no arguments'))
      if l:
          # i18n: "converted" is a keyword
          rev = getstring(l[0], _('converted requires a revision'))
  
      def _matchvalue(r):
          source = repo[r].extra().get('convert_revision', None)
          return source is not None and (rev is None or source.startswith(rev))
  
      return subset.filter(lambda r: _matchvalue(r))
  
  def date(repo, subset, x):
      """``date(interval)``
      Changesets within the interval, see :hg:`help dates`.
      """
      # i18n: "date" is a keyword
      ds = getstring(x, _("date requires a string"))
      dm = util.matchdate(ds)
      return subset.filter(lambda x: dm(repo[x].date()[0]))
  
  def desc(repo, subset, x):
      """``desc(string)``
      Search commit message for string. The match is case-insensitive.
      """
      # i18n: "desc" is a keyword
      ds = encoding.lower(getstring(x, _("desc requires a string")))
  
      def matches(x):
          c = repo[x]
          return ds in encoding.lower(c.description())
  
      return subset.filter(matches)
  
  def _descendants(repo, subset, x, followfirst=False):
      roots = getset(repo, fullreposet(repo), x)
      if not roots:
          return baseset()
      s = _revdescendants(repo, roots, followfirst)
  
      # Both sets need to be ascending in order to lazily return the union
      # in the correct order.
      base = subset & roots
      desc = subset & s
      result = base + desc
      if subset.isascending():
          result.sort()
      elif subset.isdescending():
          result.sort(reverse=True)
      else:
          result = subset & result
      return result
  
  def descendants(repo, subset, x):
      """``descendants(set)``
      Changesets which are descendants of changesets in set.
      """
      return _descendants(repo, subset, x)
  
  def _firstdescendants(repo, subset, x):
      # ``_firstdescendants(set)``
      # Like ``descendants(set)`` but follows only the first parents.
      return _descendants(repo, subset, x, followfirst=True)
  
  def destination(repo, subset, x):
      """``destination([set])``
      Changesets that were created by a graft, transplant or rebase operation,
      with the given revisions specified as the source.  Omitting the optional set
      is the same as passing all().
      """
      if x is not None:
          sources = getset(repo, fullreposet(repo), x)
      else:
          sources = fullreposet(repo)
  
      dests = set()
  
      # subset contains all of the possible destinations that can be returned, so
      # iterate over them and see if their source(s) were provided in the arg set.
      # Even if the immediate src of r is not in the arg set, src's source (or
      # further back) may be.  Scanning back further than the immediate src allows
      # transitive transplants and rebases to yield the same results as transitive
      # grafts.
      for r in subset:
          src = _getrevsource(repo, r)
          lineage = None
  
          while src is not None:
              if lineage is None:
                  lineage = list()
  
              lineage.append(r)
  
              # The visited lineage is a match if the current source is in the arg
              # set.  Since every candidate dest is visited by way of iterating
              # subset, any dests further back in the lineage will be tested by a
              # different iteration over subset.  Likewise, if the src was already
              # selected, the current lineage can be selected without going back
              # further.
              if src in sources or src in dests:
                  dests.update(lineage)
                  break
  
              r = src
              src = _getrevsource(repo, r)
  
      return subset.filter(dests.__contains__)
  
  def divergent(repo, subset, x):
      """``divergent()``
      Final successors of changesets with an alternative set of final successors.
      """
      # i18n: "divergent" is a keyword
      getargs(x, 0, 0, _("divergent takes no arguments"))
      divergent = obsmod.getrevs(repo, 'divergent')
      return subset & divergent
  
  def draft(repo, subset, x):
      """``draft()``
      Changeset in draft phase."""
      # i18n: "draft" is a keyword
      getargs(x, 0, 0, _("draft takes no arguments"))
      phase = repo._phasecache.phase
      target = phases.draft
      condition = lambda r: phase(repo, r) == target
      return subset.filter(condition, cache=False)
  
  def extinct(repo, subset, x):
      """``extinct()``
      Obsolete changesets with obsolete descendants only.
      """
      # i18n: "extinct" is a keyword
      getargs(x, 0, 0, _("extinct takes no arguments"))
      extincts = obsmod.getrevs(repo, 'extinct')
      return subset & extincts
  
  def extra(repo, subset, x):
      """``extra(label, [value])``
      Changesets with the given label in the extra metadata, with the given
      optional value.
  
      If `value` starts with `re:`, the remainder of the value is treated as
      a regular expression. To match a value that actually starts with `re:`,
      use the prefix `literal:`.
      """
  
      # i18n: "extra" is a keyword
      l = getargs(x, 1, 2, _('extra takes at least 1 and at most 2 arguments'))
      # i18n: "extra" is a keyword
      label = getstring(l[0], _('first argument to extra must be a string'))
      value = None
  
      if len(l) > 1:
          # i18n: "extra" is a keyword
          value = getstring(l[1], _('second argument to extra must be a string'))
          kind, value, matcher = _stringmatcher(value)
  
      def _matchvalue(r):
          extra = repo[r].extra()
          return label in extra and (value is None or matcher(extra[label]))
  
      return subset.filter(lambda r: _matchvalue(r))
  
  def filelog(repo, subset, x):
      """``filelog(pattern)``
      Changesets connected to the specified filelog.
  
      For performance reasons, visits only revisions mentioned in the file-level
      filelog, rather than filtering through all changesets (much faster, but
      doesn't include deletes or duplicate changes). For a slower, more accurate
      result, use ``file()``.
  
      The pattern without explicit kind like ``glob:`` is expected to be
      relative to the current directory and match against a file exactly
      for efficiency.
  
      If some linkrev points to revisions filtered by the current repoview, we'll
      work around it to return a non-filtered value.
      """
  
      # i18n: "filelog" is a keyword
      pat = getstring(x, _("filelog requires a pattern"))
      s = set()
      cl = repo.changelog
  
      if not matchmod.patkind(pat):
          f = pathutil.canonpath(repo.root, repo.getcwd(), pat)
          files = [f]
      else:
          m = matchmod.match(repo.root, repo.getcwd(), [pat], ctx=repo[None])
          files = (f for f in repo[None] if m(f))
  
      for f in files:
          backrevref = {}  # final value for: filerev -> changerev
          lowestchild = {} # lowest known filerev child of a filerev
          delayed = []     # filerev with filtered linkrev, for post-processing
          lowesthead = None # cache for manifest content of all head revisions
          fl = repo.file(f)
          for fr in list(fl):
              rev = fl.linkrev(fr)
              if rev not in cl:
                  # changerev pointed in linkrev is filtered
                  # record it for post processing.
                  delayed.append((fr, rev))
                  continue
              for p in fl.parentrevs(fr):
                  if 0 <= p and p not in lowestchild:
                      lowestchild[p] = fr
              backrevref[fr] = rev
              s.add(rev)
  
          # Post-processing of all filerevs we skipped because they were
          # filtered. If such filerevs have known and unfiltered children, this
          # means they have an unfiltered appearance out there. We'll use linkrev
          # adjustment to find one of these appearances. The lowest known child
          # will be used as a starting point because it is the best upper-bound we
          # have.
          #
          # This approach will fail when an unfiltered but linkrev-shadowed
          # appearance exists in a head changeset without unfiltered filerev
          # children anywhere.
          while delayed:
              # must be a descending iteration. To slowly fill lowest child
              # information that is of potential use by the next item.
              fr, rev = delayed.pop()
              lkr = rev
  
              child = lowestchild.get(fr)
  
              if child is None:
                  # search for existence of this file revision in a head revision.
                  # There are three possibilities:
                  # - the revision exists in a head and we can find an
                  #   introduction from there,
                  # - the revision does not exist in a head because it has been
                  #   changed since its introduction: we would have found a child
                  #   and be in the other 'else' clause,
                  # - all versions of the revision are hidden.
                  if lowesthead is None:
                      lowesthead = {}
                      for h in repo.heads():
                          fnode = repo[h].manifest().get(f)
                          if fnode is not None:
                              lowesthead[fl.rev(fnode)] = h
                  headrev = lowesthead.get(fr)
                  if headrev is None:
                      # content is nowhere unfiltered
                      continue
                  rev = repo[headrev][f].introrev()
              else:
                  # the lowest known child is a good upper bound
                  childcrev = backrevref[child]
                  # XXX this does not guarantee returning the lowest
                  # introduction of this revision, but this gives a
                  # result which is a good start and will fit in most
                  # cases. We probably need to fix the multiple
                  # introductions case properly (report each
                  # introduction, even for identical file revisions)
                  # once and for all at some point anyway.
                  for p in repo[childcrev][f].parents():
                      if p.filerev() == fr:
                          rev = p.rev()
                          break
                  if rev == lkr:  # no shadowed entry found
                      # XXX This should never happen unless some manifest points
                      # to biggish file revisions (like a revision that uses a
                      # parent that never appears in the manifest ancestors)
                      continue
  
              # Fill the data for the next iteration.
              for p in fl.parentrevs(fr):
                  if 0 <= p and p not in lowestchild:
                      lowestchild[p] = fr
              backrevref[fr] = rev
              s.add(rev)
  
      return subset & s
  
  def first(repo, subset, x):
      """``first(set, [n])``
      An alias for limit().
      """
      return limit(repo, subset, x)
  
  def _follow(repo, subset, x, name, followfirst=False):
      l = getargs(x, 0, 1, _("%s takes no arguments or a filename") % name)
      c = repo['.']
      if l:
          x = getstring(l[0], _("%s expected a filename") % name)
          if x in c:
              cx = c[x]
              s = set(ctx.rev() for ctx in cx.ancestors(followfirst=followfirst))
              # include the revision responsible for the most recent version
              s.add(cx.introrev())
          else:
              return baseset()
      else:
          s = _revancestors(repo, baseset([c.rev()]), followfirst)
  
      return subset & s
  
  def follow(repo, subset, x):
      """``follow([file])``
      An alias for ``::.`` (ancestors of the working directory's first parent).
      If a filename is specified, the history of the given file is followed,
      including copies.
      """
      return _follow(repo, subset, x, 'follow')
  
  def _followfirst(repo, subset, x):
      # ``followfirst([file])``
      # Like ``follow([file])`` but follows only the first parent of
      # every revision or file revision.
      return _follow(repo, subset, x, '_followfirst', followfirst=True)
  
  def getall(repo, subset, x):
      """``all()``
      All changesets, the same as ``0:tip``.
      """
      # i18n: "all" is a keyword
      getargs(x, 0, 0, _("all takes no arguments"))
      return subset & spanset(repo)  # drop "null" if any
  
  def grep(repo, subset, x):
      """``grep(regex)``
      Like ``keyword(string)`` but accepts a regex. Use ``grep(r'...')``
      to ensure special escape characters are handled correctly. Unlike
      ``keyword(string)``, the match is case-sensitive.
      """
      try:
          # i18n: "grep" is a keyword
          gr = re.compile(getstring(x, _("grep requires a string")))
      except re.error, e:
          raise error.ParseError(_('invalid match pattern: %s') % e)
  
      def matches(x):
          c = repo[x]
          for e in c.files() + [c.user(), c.description()]:
              if gr.search(e):
                  return True
          return False
  
      return subset.filter(matches)
  
  def _matchfiles(repo, subset, x):
      # _matchfiles takes a revset list of prefixed arguments:
      #
      #   [p:foo, i:bar, x:baz]
      #
      # builds a match object from them and filters subset. Allowed
      # prefixes are 'p:' for regular patterns, 'i:' for include
      # patterns and 'x:' for exclude patterns. Use 'r:' prefix to pass
      # a revision identifier, or the empty string to reference the
      # working directory, from which the match object is
      # initialized. Use 'd:' to set the default matching mode, default
      # to 'glob'. At most one 'r:' and 'd:' argument can be passed.
  
      # i18n: "_matchfiles" is a keyword
      l = getargs(x, 1, -1, _("_matchfiles requires at least one argument"))
      pats, inc, exc = [], [], []
      rev, default = None, None
      for arg in l:
          # i18n: "_matchfiles" is a keyword
          s = getstring(arg, _("_matchfiles requires string arguments"))
          prefix, value = s[:2], s[2:]
          if prefix == 'p:':
              pats.append(value)
          elif prefix == 'i:':
              inc.append(value)
          elif prefix == 'x:':
              exc.append(value)
          elif prefix == 'r:':
              if rev is not None:
                  # i18n: "_matchfiles" is a keyword
                  raise error.ParseError(_('_matchfiles expected at most one '
                                           'revision'))
              if value != '': # empty means working directory; leave rev as None
                  rev = value
          elif prefix == 'd:':
              if default is not None:
                  # i18n: "_matchfiles" is a keyword
                  raise error.ParseError(_('_matchfiles expected at most one '
                                           'default mode'))
              default = value
          else:
              # i18n: "_matchfiles" is a keyword
              raise error.ParseError(_('invalid _matchfiles prefix: %s') % prefix)
      if not default:
          default = 'glob'
  
      m = matchmod.match(repo.root, repo.getcwd(), pats, include=inc,
                         exclude=exc, ctx=repo[rev], default=default)
  
      def matches(x):
          for f in repo[x].files():
              if m(f):
                  return True
          return False
  
      return subset.filter(matches)
  
  def hasfile(repo, subset, x):
      """``file(pattern)``
      Changesets affecting files matched by pattern.
  
      For a faster but less accurate result, consider using ``filelog()``
      instead.
  
      This predicate uses ``glob:`` as the default kind of pattern.
      """
      # i18n: "file" is a keyword
      pat = getstring(x, _("file requires a pattern"))
      return _matchfiles(repo, subset, ('string', 'p:' + pat))
  
  def head(repo, subset, x):
      """``head()``
      Changeset is a named branch head.
      """
      # i18n: "head" is a keyword
      getargs(x, 0, 0, _("head takes no arguments"))
      hs = set()
      for b, ls in repo.branchmap().iteritems():
          hs.update(repo[h].rev() for h in ls)
      return baseset(hs).filter(subset.__contains__)
  
  def heads(repo, subset, x):
      """``heads(set)``
      Members of set with no children in set.
      """
      s = getset(repo, subset, x)
      ps = parents(repo, subset, x)
      return s - ps
  
  def hidden(repo, subset, x):
      """``hidden()``
      Hidden changesets.
      """
      # i18n: "hidden" is a keyword
      getargs(x, 0, 0, _("hidden takes no arguments"))
      hiddenrevs = repoview.filterrevs(repo, 'visible')
      return subset & hiddenrevs
  
  def keyword(repo, subset, x):
      """``keyword(string)``
      Search commit message, user name, and names of changed files for
      string. The match is case-insensitive.
      """
      # i18n: "keyword" is a keyword
      kw = encoding.lower(getstring(x, _("keyword requires a string")))
  
      def matches(r):
          c = repo[r]
          return util.any(kw in encoding.lower(t) for t in c.files() + [c.user(),
              c.description()])
  
      return subset.filter(matches)
  
  def limit(repo, subset, x):
      """``limit(set, [n])``
      First n members of set, defaulting to 1.
      """
      # i18n: "limit" is a keyword
      l = getargs(x, 1, 2, _("limit requires one or two arguments"))
      try:
          lim = 1
          if len(l) == 2:
              # i18n: "limit" is a keyword
              lim = int(getstring(l[1], _("limit requires a number")))
      except (TypeError, ValueError):
          # i18n: "limit" is a keyword
          raise error.ParseError(_("limit expects a number"))
      ss = subset
      os = getset(repo, fullreposet(repo), l[0])
      result = []
      it = iter(os)
      for x in xrange(lim):
          try:
              y = it.next()
              if y in ss:
                  result.append(y)
          except (StopIteration):
              break
      return baseset(result)
  
  def last(repo, subset, x):
      """``last(set, [n])``
      Last n members of set, defaulting to 1.
      """
      # i18n: "last" is a keyword
      l = getargs(x, 1, 2, _("last requires one or two arguments"))
      try:
          lim = 1
          if len(l) == 2:
              # i18n: "last" is a keyword
              lim = int(getstring(l[1], _("last requires a number")))
      except (TypeError, ValueError):
          # i18n: "last" is a keyword
          raise error.ParseError(_("last expects a number"))
      ss = subset
      os = getset(repo, fullreposet(repo), l[0])
      os.reverse()
      result = []
      it = iter(os)
      for x in xrange(lim):
          try:
              y = it.next()
              if y in ss:
                  result.append(y)
          except (StopIteration):
              break
      return baseset(result)
  
  def maxrev(repo, subset, x):
      """``max(set)``
      Changeset with highest revision number in set.
      """
      os = getset(repo, fullreposet(repo), x)
      if os:
          m = os.max()
          if m in subset:
              return baseset([m])
      return baseset()
  
  def merge(repo, subset, x):
      """``merge()``
      Changeset is a merge changeset.
      """
      # i18n: "merge" is a keyword
      getargs(x, 0, 0, _("merge takes no arguments"))
      cl = repo.changelog
      return subset.filter(lambda r: cl.parentrevs(r)[1] != -1)
  
  def branchpoint(repo, subset, x):
      """``branchpoint()``
      Changesets with more than one child.
      """
      # i18n: "branchpoint" is a keyword
      getargs(x, 0, 0, _("branchpoint takes no arguments"))
      cl = repo.changelog
      if not subset:
          return baseset()
      baserev = min(subset)
      parentscount = [0]*(len(repo) - baserev)
      for r in cl.revs(start=baserev + 1):
          for p in cl.parentrevs(r):
              if p >= baserev:
                  parentscount[p - baserev] += 1
      return subset.filter(lambda r: parentscount[r - baserev] > 1)
  
  def minrev(repo, subset, x):
      """``min(set)``
      Changeset with lowest revision number in set.
      """
      os = getset(repo, fullreposet(repo), x)
      if os:
          m = os.min()
          if m in subset:
              return baseset([m])
      return baseset()
  
  def modifies(repo, subset, x):
      """``modifies(pattern)``
      Changesets modifying files matched by pattern.
  
      The pattern without explicit kind like ``glob:`` is expected to be
      relative to the current directory and match against a file or a
      directory.
      """
      # i18n: "modifies" is a keyword
      pat = getstring(x, _("modifies requires a pattern"))
      return checkstatus(repo, subset, pat, 0)
  
  def named(repo, subset, x):
      """``named(namespace)``
      The changesets in a given namespace.
  
      If `namespace` starts with `re:`, the remainder of the string is treated as
      a regular expression. To match a namespace that actually starts with `re:`,
      use the prefix `literal:`.
      """
      # i18n: "named" is a keyword
      args = getargs(x, 1, 1, _('named requires a namespace argument'))
  
      ns = getstring(args[0],
                     # i18n: "named" is a keyword
                     _('the argument to named must be a string'))
      kind, pattern, matcher = _stringmatcher(ns)
      namespaces = set()
      if kind == 'literal':
          if pattern not in repo.names:
              raise error.RepoLookupError(_("namespace '%s' does not exist")
                                          % ns)
          namespaces.add(repo.names[pattern])
      else:
          for name, ns in repo.names.iteritems():
              if matcher(name):
                  namespaces.add(ns)
          if not namespaces:
              raise error.RepoLookupError(_("no namespace exists"
                                            " that match '%s'") % pattern)
  
      names = set()
      for ns in namespaces:
          for name in ns.listnames(repo):
              if name not in ns.deprecated:
                  names.update(repo[n].rev() for n in ns.nodes(repo, name))
  
      names -= set([node.nullrev])
      return subset & names
  
  def node_(repo, subset, x):
      """``id(string)``
      Revision non-ambiguously specified by the given hex string prefix.
      """
      # i18n: "id" is a keyword
      l = getargs(x, 1, 1, _("id requires one argument"))
      # i18n: "id" is a keyword
      n = getstring(l[0], _("id requires a string"))
      if len(n) == 40:
          try:
              rn = repo.changelog.rev(node.bin(n))
          except (LookupError, TypeError):
              rn = None
      else:
          rn = None
          pm = repo.changelog._partialmatch(n)
          if pm is not None:
              rn = repo.changelog.rev(pm)
  
      if rn is None:
          return baseset()
      result = baseset([rn])
      return result & subset
  
  def obsolete(repo, subset, x):
      """``obsolete()``
      Mutable changeset with a newer version."""
      # i18n: "obsolete" is a keyword
      getargs(x, 0, 0, _("obsolete takes no arguments"))
      obsoletes = obsmod.getrevs(repo, 'obsolete')
      return subset & obsoletes
  
  def only(repo, subset, x):
      """``only(set, [set])``
      Changesets that are ancestors of the first set that are not ancestors
      of any other head in the repo. If a second set is specified, the result
      is ancestors of the first set that are not ancestors of the second set
      (i.e. ::<set1> - ::<set2>).
      """
      cl = repo.changelog
      # i18n: "only" is a keyword
      args = getargs(x, 1, 2, _('only takes one or two arguments'))
      include = getset(repo, fullreposet(repo), args[0])
      if len(args) == 1:
          if not include:
              return baseset()
  
          descendants = set(_revdescendants(repo, include, False))
          exclude = [rev for rev in cl.headrevs()
              if not rev in descendants and not rev in include]
      else:
          exclude = getset(repo, fullreposet(repo), args[1])
  
      results = set(cl.findmissingrevs(common=exclude, heads=include))
      return subset & results
  
  def origin(repo, subset, x):
      """``origin([set])``
      Changesets that were specified as a source for the grafts, transplants or
      rebases that created the given revisions.  Omitting the optional set is the
      same as passing all().  If a changeset created by these operations is itself
      specified as a source for one of these operations, only the source changeset
      for the first operation is selected.
      """
      if x is not None:
          dests = getset(repo, fullreposet(repo), x)
      else:
          dests = fullreposet(repo)
  
      def _firstsrc(rev):
          src = _getrevsource(repo, rev)
          if src is None:
              return None
  
          while True:
              prev = _getrevsource(repo, src)
  
              if prev is None:
                  return src
              src = prev
  
      o = set([_firstsrc(r) for r in dests])
      o -= set([None])
      return subset & o
  
  def outgoing(repo, subset, x):
      """``outgoing([path])``
      Changesets not found in the specified destination repository, or the
      default push location.
      """
      # Avoid cycles.
      import discovery
      import hg
      # i18n: "outgoing" is a keyword
      l = getargs(x, 0, 1, _("outgoing takes one or no arguments"))
      # i18n: "outgoing" is a keyword
      dest = l and getstring(l[0], _("outgoing requires a repository path")) or ''
      dest = repo.ui.expandpath(dest or 'default-push', dest or 'default')
      dest, branches = hg.parseurl(dest)
      revs, checkout = hg.addbranchrevs(repo, repo, branches, [])
      if revs:
          revs = [repo.lookup(rev) for rev in revs]
      other = hg.peer(repo, {}, dest)
      repo.ui.pushbuffer()
      outgoing = discovery.findcommonoutgoing(repo, other, onlyheads=revs)
      repo.ui.popbuffer()
      cl = repo.changelog
      o = set([cl.rev(r) for r in outgoing.missing])
      return subset & o
  
  def p1(repo, subset, x):
      """``p1([set])``
      First parent of changesets in set, or the working directory.
      """
      if x is None:
          p = repo[x].p1().rev()
          if p >= 0:
              return subset & baseset([p])
          return baseset()
  
      ps = set()
      cl = repo.changelog
      for r in getset(repo, fullreposet(repo), x):
          ps.add(cl.parentrevs(r)[0])
      ps -= set([node.nullrev])
      return subset & ps
  
  def p2(repo, subset, x):
      """``p2([set])``
      Second parent of changesets in set, or the working directory.
      """
      if x is None:
          ps = repo[x].parents()
          try:
              p = ps[1].rev()
              if p >= 0:
                  return subset & baseset([p])
              return baseset()
          except IndexError:
              return baseset()
  
      ps = set()
      cl = repo.changelog
      for r in getset(repo, fullreposet(repo), x):
          ps.add(cl.parentrevs(r)[1])
      ps -= set([node.nullrev])
      return subset & ps
  
  def parents(repo, subset, x):
      """``parents([set])``
      The set of all parents for all changesets in set, or the working directory.
      """
      if x is None:
          ps = set(p.rev() for p in repo[x].parents())
      else:
          ps = set()
          cl = repo.changelog
          for r in getset(repo, fullreposet(repo), x):
              ps.update(cl.parentrevs(r))
      ps -= set([node.nullrev])
      return subset & ps
  
  def parentspec(repo, subset, x, n):
      """``set^0``
      The set.
      ``set^1`` (or ``set^``), ``set^2``
      First or second parent, respectively, of all changesets in set.
      """
      try:
          n = int(n[1])
          if n not in (0, 1, 2):
              raise ValueError
      except (TypeError, ValueError):
          raise error.ParseError(_("^ expects a number 0, 1, or 2"))
      ps = set()
      cl = repo.changelog
      for r in getset(repo, fullreposet(repo), x):
          if n == 0:
              ps.add(r)
          elif n == 1:
              ps.add(cl.parentrevs(r)[0])
          elif n == 2:
              parents = cl.parentrevs(r)
              if len(parents) > 1:
                  ps.add(parents[1])
      return subset & ps
  
  def present(repo, subset, x):
      """``present(set)``
      An empty set, if any revision in set isn't found; otherwise,
      all revisions in set.
  
      If any of specified revisions is not present in the local repository,
      the query is normally aborted. But this predicate allows the query
      to continue even in such cases.
      """
      try:
          return getset(repo, subset, x)
      except error.RepoLookupError:
          return baseset()
  
  def public(repo, subset, x):
      """``public()``
      Changeset in public phase."""
      # i18n: "public" is a keyword
      getargs(x, 0, 0, _("public takes no arguments"))
      phase = repo._phasecache.phase
      target = phases.public
      condition = lambda r: phase(repo, r) == target
      return subset.filter(condition, cache=False)
  
  def remote(repo, subset, x):
      """``remote([id [,path]])``
      Local revision that corresponds to the given identifier in a
      remote repository, if present. Here, the '.' identifier is a
      synonym for the current local branch.
      """
  
      import hg # avoid start-up nasties
      # i18n: "remote" is a keyword
      l = getargs(x, 0, 2, _("remote takes one, two or no arguments"))
  
      q = '.'
      if len(l) > 0:
      # i18n: "remote" is a keyword
          q = getstring(l[0], _("remote requires a string id"))
      if q == '.':
          q = repo['.'].branch()
  
      dest = ''
      if len(l) > 1:
          # i18n: "remote" is a keyword
          dest = getstring(l[1], _("remote requires a repository path"))
      dest = repo.ui.expandpath(dest or 'default')
      dest, branches = hg.parseurl(dest)
      revs, checkout = hg.addbranchrevs(repo, repo, branches, [])
      if revs:
          revs = [repo.lookup(rev) for rev in revs]
      other = hg.peer(repo, {}, dest)
      n = other.lookup(q)
      if n in repo:
          r = repo[n].rev()
          if r in subset:
              return baseset([r])
      return baseset()
  
  def removes(repo, subset, x):
      """``removes(pattern)``
      Changesets which remove files matching pattern.
  
      The pattern without explicit kind like ``glob:`` is expected to be
      relative to the current directory and match against a file or a
      directory.
      """
      # i18n: "removes" is a keyword
      pat = getstring(x, _("removes requires a pattern"))
      return checkstatus(repo, subset, pat, 2)
  
  def rev(repo, subset, x):
      """``rev(number)``
      Revision with the given numeric identifier.
      """
      # i18n: "rev" is a keyword
      l = getargs(x, 1, 1, _("rev requires one argument"))
      try:
          # i18n: "rev" is a keyword
          l = int(getstring(l[0], _("rev requires a number")))
      except (TypeError, ValueError):
          # i18n: "rev" is a keyword
          raise error.ParseError(_("rev expects a number"))
      if l not in repo.changelog and l != node.nullrev:
          return baseset()
      return subset & baseset([l])
  
  def matching(repo, subset, x):
      """``matching(revision [, field])``
      Changesets in which a given set of fields match the set of fields in the
      selected revision or set.
  
      To match more than one field pass the list of fields to match separated
      by spaces (e.g. ``author description``).
  
      Valid fields are most regular revision fields and some special fields.
  
      Regular revision fields are ``description``, ``author``, ``branch``,
      ``date``, ``files``, ``phase``, ``parents``, ``substate``, ``user``
      and ``diff``.
      Note that ``author`` and ``user`` are synonyms. ``diff`` refers to the
      contents of the revision. Two revisions matching their ``diff`` will
      also match their ``files``.
  
      Special fields are ``summary`` and ``metadata``:
      ``summary`` matches the first line of the description.
      ``metadata`` is equivalent to matching ``description user date``
      (i.e. it matches the main metadata fields).
  
      ``metadata`` is the default field which is used when no fields are
      specified. You can match more than one field at a time.
      """
      # i18n: "matching" is a keyword
      l = getargs(x, 1, 2, _("matching takes 1 or 2 arguments"))
  
      revs = getset(repo, fullreposet(repo), l[0])
  
      fieldlist = ['metadata']
      if len(l) > 1:
              fieldlist = getstring(l[1],
                  # i18n: "matching" is a keyword
                  _("matching requires a string "
                  "as its second argument")).split()
  
      # Make sure that there are no repeated fields,
      # expand the 'special' 'metadata' field type
      # and check the 'files' whenever we check the 'diff'
      fields = []
      for field in fieldlist:
          if field == 'metadata':
              fields += ['user', 'description', 'date']
          elif field == 'diff':
              # a revision matching the diff must also match the files
              # since matching the diff is very costly, make sure to
              # also match the files first
              fields += ['files', 'diff']
          else:
              if field == 'author':
                  field = 'user'
              fields.append(field)
      fields = set(fields)
      if 'summary' in fields and 'description' in fields:
          # If a revision matches its description it also matches its summary
          fields.discard('summary')
  
      # We may want to match more than one field
      # Not all fields take the same amount of time to be matched
      # Sort the selected fields in order of increasing matching cost
      fieldorder = ['phase', 'parents', 'user', 'date', 'branch', 'summary',
          'files', 'description', 'substate', 'diff']
      def fieldkeyfunc(f):
          try:
              return fieldorder.index(f)
          except ValueError:
              # assume an unknown field is very costly
              return len(fieldorder)
      fields = list(fields)
      fields.sort(key=fieldkeyfunc)
  
      # Each field will be matched with its own "getfield" function
      # which will be added to the getfieldfuncs array of functions
      getfieldfuncs = []
      _funcs = {
          'user': lambda r: repo[r].user(),
          'branch': lambda r: repo[r].branch(),
          'date': lambda r: repo[r].date(),
          'description': lambda r: repo[r].description(),
          'files': lambda r: repo[r].files(),
          'parents': lambda r: repo[r].parents(),
          'phase': lambda r: repo[r].phase(),
          'substate': lambda r: repo[r].substate,
          'summary': lambda r: repo[r].description().splitlines()[0],
          'diff': lambda r: list(repo[r].diff(git=True),)
      }
      for info in fields:
          getfield = _funcs.get(info, None)
          if getfield is None:
              raise error.ParseError(
                  # i18n: "matching" is a keyword
                  _("unexpected field name passed to matching: %s") % info)
          getfieldfuncs.append(getfield)
      # convert the getfield array of functions into a "getinfo" function
      # which returns an array of field values (or a single value if there
      # is only one field to match)
      getinfo = lambda r: [f(r) for f in getfieldfuncs]
  
      def matches(x):
          for rev in revs:
              target = getinfo(rev)
              match = True
              for n, f in enumerate(getfieldfuncs):
                  if target[n] != f(x):
                      match = False
              if match:
                  return True
          return False
  
      return subset.filter(matches)
  
  def reverse(repo, subset, x):
      """``reverse(set)``
      Reverse order of set.
      """
      l = getset(repo, subset, x)
      l.reverse()
      return l
  
  def roots(repo, subset, x):
      """``roots(set)``
      Changesets in set with no parent changeset in set.
      """
      s = getset(repo, fullreposet(repo), x)
      subset = baseset([r for r in s if r in subset])
      cs = _children(repo, subset, s)
      return subset - cs
  
  def secret(repo, subset, x):
      """``secret()``
      Changeset in secret phase."""
      # i18n: "secret" is a keyword
      getargs(x, 0, 0, _("secret takes no arguments"))
      phase = repo._phasecache.phase
      target = phases.secret
      condition = lambda r: phase(repo, r) == target
      return subset.filter(condition, cache=False)
  
  def sort(repo, subset, x):
      """``sort(set[, [-]key...])``
      Sort set by keys. The default sort order is ascending, specify a key
      as ``-key`` to sort in descending order.
  
      The keys can be:
  
      - ``rev`` for the revision number,
      - ``branch`` for the branch name,
      - ``desc`` for the commit message (description),
      - ``user`` for user name (``author`` can be used as an alias),
      - ``date`` for the commit date
      """
      # i18n: "sort" is a keyword
      l = getargs(x, 1, 2, _("sort requires one or two arguments"))
      keys = "rev"
      if len(l) == 2:
          # i18n: "sort" is a keyword
          keys = getstring(l[1], _("sort spec must be a string"))
  
      s = l[0]
      keys = keys.split()
      l = []
      def invert(s):
          return "".join(chr(255 - ord(c)) for c in s)
      revs = getset(repo, subset, s)
      if keys == ["rev"]:
          revs.sort()
          return revs
      elif keys == ["-rev"]:
          revs.sort(reverse=True)
          return revs
      for r in revs:
          c = repo[r]
          e = []
          for k in keys:
              if k == 'rev':
                  e.append(r)
              elif k == '-rev':
                  e.append(-r)
              elif k == 'branch':
                  e.append(c.branch())
              elif k == '-branch':
                  e.append(invert(c.branch()))
              elif k == 'desc':
                  e.append(c.description())
              elif k == '-desc':
                  e.append(invert(c.description()))
              elif k in 'user author':
                  e.append(c.user())
              elif k in '-user -author':
                  e.append(invert(c.user()))
              elif k == 'date':
                  e.append(c.date()[0])
              elif k == '-date':
                  e.append(-c.date()[0])
              else:
                  raise error.ParseError(_("unknown sort key %r") % k)
          e.append(r)
          l.append(e)
      l.sort()
      return baseset([e[-1] for e in l])
  
  def subrepo(repo, subset, x):
      """``subrepo([pattern])``
      Changesets that add, modify or remove the given subrepo.  If no subrepo
      pattern is named, any subrepo changes are returned.
      """
      # i18n: "subrepo" is a keyword
      args = getargs(x, 0, 1, _('subrepo takes at most one argument'))
      if len(args) != 0:
          pat = getstring(args[0], _("subrepo requires a pattern"))
  
      m = matchmod.exact(repo.root, repo.root, ['.hgsubstate'])
  
      def submatches(names):
          k, p, m = _stringmatcher(pat)
          for name in names:
              if m(name):
                  yield name
  
      def matches(x):
          c = repo[x]
          s = repo.status(c.p1().node(), c.node(), match=m)
  
          if len(args) == 0:
              return s.added or s.modified or s.removed
  
          if s.added:
              return util.any(submatches(c.substate.keys()))
  
          if s.modified:
              subs = set(c.p1().substate.keys())
              subs.update(c.substate.keys())
  
              for path in submatches(subs):
                  if c.p1().substate.get(path) != c.substate.get(path):
                      return True
  
          if s.removed:
              return util.any(submatches(c.p1().substate.keys()))
  
          return False
  
      return subset.filter(matches)
  
  def _stringmatcher(pattern):
      """
      accepts a string, possibly starting with 're:' or 'literal:' prefix.
      returns the matcher name, pattern, and matcher function.
      missing or unknown prefixes are treated as literal matches.
  
      helper for tests:
      >>> def test(pattern, *tests):
      ...     kind, pattern, matcher = _stringmatcher(pattern)
      ...     return (kind, pattern, [bool(matcher(t)) for t in tests])
  
      exact matching (no prefix):
      >>> test('abcdefg', 'abc', 'def', 'abcdefg')
      ('literal', 'abcdefg', [False, False, True])
  
      regex matching ('re:' prefix)
      >>> test('re:a.+b', 'nomatch', 'fooadef', 'fooadefbar')
      ('re', 'a.+b', [False, False, True])
  
      force exact matches ('literal:' prefix)
      >>> test('literal:re:foobar', 'foobar', 're:foobar')
      ('literal', 're:foobar', [False, True])
  
      unknown prefixes are ignored and treated as literals
      >>> test('foo:bar', 'foo', 'bar', 'foo:bar')
      ('literal', 'foo:bar', [False, False, True])
      """
      if pattern.startswith('re:'):
          pattern = pattern[3:]
          try:
              regex = re.compile(pattern)
          except re.error, e:
              raise error.ParseError(_('invalid regular expression: %s')
                                     % e)
          return 're', pattern, regex.search
      elif pattern.startswith('literal:'):
          pattern = pattern[8:]
      return 'literal', pattern, pattern.__eq__
  
  def _substringmatcher(pattern):
      kind, pattern, matcher = _stringmatcher(pattern)
      if kind == 'literal':
          matcher = lambda s: pattern in s
      return kind, pattern, matcher
  
  def tag(repo, subset, x):
      """``tag([name])``
      The specified tag by name, or all tagged revisions if no name is given.
  
      If `name` starts with `re:`, the remainder of the name is treated as
      a regular expression. To match a tag that actually starts with `re:`,
      use the prefix `literal:`.
      """
      # i18n: "tag" is a keyword
      args = getargs(x, 0, 1, _("tag takes one or no arguments"))
      cl = repo.changelog
      if args:
          pattern = getstring(args[0],
                              # i18n: "tag" is a keyword
                              _('the argument to tag must be a string'))
          kind, pattern, matcher = _stringmatcher(pattern)
          if kind == 'literal':
              # avoid resolving all tags
              tn = repo._tagscache.tags.get(pattern, None)
              if tn is None:
                  raise error.RepoLookupError(_("tag '%s' does not exist")
                                              % pattern)
              s = set([repo[tn].rev()])
          else:
              s = set([cl.rev(n) for t, n in repo.tagslist() if matcher(t)])
      else:
          s = set([cl.rev(n) for t, n in repo.tagslist() if t != 'tip'])
      return subset & s
  
  def tagged(repo, subset, x):
      return tag(repo, subset, x)
  
  def unstable(repo, subset, x):
      """``unstable()``
      Non-obsolete changesets with obsolete ancestors.
      """
      # i18n: "unstable" is a keyword
      getargs(x, 0, 0, _("unstable takes no arguments"))
      unstables = obsmod.getrevs(repo, 'unstable')
      return subset & unstables
  
  
  def user(repo, subset, x):
      """``user(string)``
      User name contains string. The match is case-insensitive.
  
      If `string` starts with `re:`, the remainder of the string is treated as
      a regular expression. To match a user that actually contains `re:`, use
      the prefix `literal:`.
      """
      return author(repo, subset, x)
  
  # experimental
  def wdir(repo, subset, x):
      # i18n: "wdir" is a keyword
      getargs(x, 0, 0, _("wdir takes no arguments"))
      if None in subset or isinstance(subset, fullreposet):
          return baseset([None])
      return baseset()
  
  # for internal use
  def _list(repo, subset, x):
      s = getstring(x, "internal error")
      if not s:
          return baseset()
      ls = [repo[r].rev() for r in s.split('\0')]
      s = subset
      return baseset([r for r in ls if r in s])
  
  # for internal use
  def _intlist(repo, subset, x):
      s = getstring(x, "internal error")
      if not s:
          return baseset()
      ls = [int(r) for r in s.split('\0')]
      s = subset
      return baseset([r for r in ls if r in s])
  
  # for internal use
  def _hexlist(repo, subset, x):
      s = getstring(x, "internal error")
      if not s:
          return baseset()
      cl = repo.changelog
      ls = [cl.rev(node.bin(r)) for r in s.split('\0')]
      s = subset
      return baseset([r for r in ls if r in s])
  
  symbols = {
      "adds": adds,
      "all": getall,
      "ancestor": ancestor,
      "ancestors": ancestors,
      "_firstancestors": _firstancestors,
      "author": author,
      "bisect": bisect,
      "bisected": bisected,
      "bookmark": bookmark,
      "branch": branch,
      "branchpoint": branchpoint,
      "bumped": bumped,
      "bundle": bundle,
      "children": children,
      "closed": closed,
      "contains": contains,
      "converted": converted,
      "date": date,
      "desc": desc,
      "descendants": descendants,
      "_firstdescendants": _firstdescendants,
      "destination": destination,
      "divergent": divergent,
      "draft": draft,
      "extinct": extinct,
      "extra": extra,
      "file": hasfile,
      "filelog": filelog,
      "first": first,
      "follow": follow,
      "_followfirst": _followfirst,
      "grep": grep,
      "head": head,
      "heads": heads,
      "hidden": hidden,
      "id": node_,
      "keyword": keyword,
      "last": last,
      "limit": limit,
      "_matchfiles": _matchfiles,
      "max": maxrev,
      "merge": merge,
      "min": minrev,
      "modifies": modifies,
      "named": named,
      "obsolete": obsolete,
      "only": only,
      "origin": origin,
      "outgoing": outgoing,
      "p1": p1,
      "p2": p2,
      "parents": parents,
      "present": present,
      "public": public,
      "remote": remote,
      "removes": removes,
      "rev": rev,
      "reverse": reverse,
      "roots": roots,
      "sort": sort,
      "secret": secret,
      "subrepo": subrepo,
      "matching": matching,
      "tag": tag,
      "tagged": tagged,
      "user": user,
      "unstable": unstable,
      "wdir": wdir,
      "_list": _list,
      "_intlist": _intlist,
      "_hexlist": _hexlist,
  }
  
  # symbols which can't be used for a DoS attack for any given input
  # (e.g. those which accept regexes as plain strings shouldn't be included)
  # functions that just return a lot of changesets (like all) don't count here
  safesymbols = set([
      "adds",
      "all",
      "ancestor",
      "ancestors",
      "_firstancestors",
      "author",
      "bisect",
      "bisected",
      "bookmark",
      "branch",
      "branchpoint",
      "bumped",
      "bundle",
      "children",
      "closed",
      "converted",
      "date",
      "desc",
      "descendants",
      "_firstdescendants",
      "destination",
      "divergent",
      "draft",
      "extinct",
      "extra",
      "file",
      "filelog",
      "first",
      "follow",
      "_followfirst",
      "head",
      "heads",
      "hidden",
      "id",
      "keyword",
      "last",
      "limit",
      "_matchfiles",
      "max",
      "merge",
      "min",
      "modifies",
      "obsolete",
      "only",
      "origin",
      "outgoing",
      "p1",
      "p2",
      "parents",
      "present",
      "public",
      "remote",
      "removes",
      "rev",
      "reverse",
      "roots",
      "sort",
      "secret",
      "matching",
      "tag",
      "tagged",
      "user",
      "unstable",
      "wdir",
      "_list",
      "_intlist",
      "_hexlist",
  ])
  
  methods = {
      "range": rangeset,
      "dagrange": dagrange,
      "string": stringset,
      "symbol": symbolset,
      "and": andset,
      "or": orset,
      "not": notset,
      "list": listset,
      "func": func,
      "ancestor": ancestorspec,
      "parent": parentspec,
      "parentpost": p1,
      "only": only,
  }
  
  def optimize(x, small):
      if x is None:
          return 0, x
  
      smallbonus = 1
      if small:
          smallbonus = .5
  
      op = x[0]
      if op == 'minus':
          return optimize(('and', x[1], ('not', x[2])), small)
      elif op == 'only':
          return optimize(('func', ('symbol', 'only'),
                           ('list', x[1], x[2])), small)
      elif op == 'onlypost':
          return optimize(('func', ('symbol', 'only'), x[1]), small)
      elif op == 'dagrangepre':
          return optimize(('func', ('symbol', 'ancestors'), x[1]), small)
      elif op == 'dagrangepost':
          return optimize(('func', ('symbol', 'descendants'), x[1]), small)
      elif op == 'rangepre':
          return optimize(('range', ('string', '0'), x[1]), small)
      elif op == 'rangepost':
          return optimize(('range', x[1], ('string', 'tip')), small)
      elif op == 'negate':
          return optimize(('string',
                           '-' + getstring(x[1], _("can't negate that"))), small)
      elif op in 'string symbol negate':
          return smallbonus, x # single revisions are small
      elif op == 'and':
          wa, ta = optimize(x[1], True)
          wb, tb = optimize(x[2], True)
  
          # (::x and not ::y)/(not ::y and ::x) have a fast path
          def isonly(revs, bases):
              return (
                  revs[0] == 'func'
                  and getstring(revs[1], _('not a symbol')) == 'ancestors'
                  and bases[0] == 'not'
                  and bases[1][0] == 'func'
                  and getstring(bases[1][1], _('not a symbol')) == 'ancestors')
  
          w = min(wa, wb)
          if isonly(ta, tb):
              return w, ('func', ('symbol', 'only'), ('list', ta[2], tb[1][2]))
          if isonly(tb, ta):
              return w, ('func', ('symbol', 'only'), ('list', tb[2], ta[1][2]))
  
          if wa > wb:
              return w, (op, tb, ta)
          return w, (op, ta, tb)
      elif op == 'or':
          wa, ta = optimize(x[1], False)
          wb, tb = optimize(x[2], False)
          if wb < wa:
              wb, wa = wa, wb
          return max(wa, wb), (op, ta, tb)
      elif op == 'not':
          o = optimize(x[1], not small)
          return o[0], (op, o[1])
      elif op == 'parentpost':
          o = optimize(x[1], small)
          return o[0], (op, o[1])
      elif op == 'group':
          return optimize(x[1], small)
      elif op in 'dagrange range list parent ancestorspec':
          if op == 'parent':
              # x^:y means (x^) : y, not x ^ (:y)
              post = ('parentpost', x[1])
              if x[2][0] == 'dagrangepre':
                  return optimize(('dagrange', post, x[2][1]), small)
              elif x[2][0] == 'rangepre':
                  return optimize(('range', post, x[2][1]), small)
  
          wa, ta = optimize(x[1], small)
          wb, tb = optimize(x[2], small)
          return wa + wb, (op, ta, tb)
      elif op == 'func':
          f = getstring(x[1], _("not a symbol"))
          wa, ta = optimize(x[2], small)
          if f in ("author branch closed date desc file grep keyword "
                   "outgoing user"):
              w = 10 # slow
          elif f in "modifies adds removes":
              w = 30 # slower
          elif f == "contains":
              w = 100 # very slow
          elif f == "ancestor":
              w = 1 * smallbonus
          elif f in "reverse limit first _intlist":
              w = 0
          elif f in "sort":
              w = 10 # assume most sorts look at changelog
          else:
              w = 1
          return w + wa, (op, x[1], ta)
      return 1, x
  
  _aliasarg = ('func', ('symbol', '_aliasarg'))
  def _getaliasarg(tree):
      """If tree matches ('func', ('symbol', '_aliasarg'), ('string', X))
      return X, None otherwise.
      """
      if (len(tree) == 3 and tree[:2] == _aliasarg
          and tree[2][0] == 'string'):
          return tree[2][1]
      return None
  
  def _checkaliasarg(tree, known=None):
      """Check tree contains no _aliasarg construct or only ones which
      value is in known. Used to avoid alias placeholders injection.
      """
      if isinstance(tree, tuple):
          arg = _getaliasarg(tree)
          if arg is not None and (not known or arg not in known):
              raise error.UnknownIdentifier('_aliasarg', [])
          for t in tree:
              _checkaliasarg(t, known)
  
  # the set of valid characters for the initial letter of symbols in
  # alias declarations and definitions
  _aliassyminitletters = set(c for c in [chr(i) for i in xrange(256)]
                             if c.isalnum() or c in '._@$' or ord(c) > 127)
  
  def _tokenizealias(program, lookup=None):
      """Parse alias declaration/definition into a stream of tokens
  
      This allows symbol names to use also ``$`` as an initial letter
      (for backward compatibility), and callers of this function should
      examine whether ``$`` is used also for unexpected symbols or not.
      """
      return tokenize(program, lookup=lookup,
                      syminitletters=_aliassyminitletters)
  
  def _parsealiasdecl(decl):
      """Parse alias declaration ``decl``
  
      This returns ``(name, tree, args, errorstr)`` tuple:
  
      - ``name``: of declared alias (may be ``decl`` itself at error)
      - ``tree``: parse result (or ``None`` at error)
      - ``args``: list of alias argument names (or None for symbol declaration)
      - ``errorstr``: detail about detected error (or None)
  
      >>> _parsealiasdecl('foo')
      ('foo', ('symbol', 'foo'), None, None)
      >>> _parsealiasdecl('$foo')
      ('$foo', None, None, "'$' not for alias arguments")
      >>> _parsealiasdecl('foo::bar')
      ('foo::bar', None, None, 'invalid format')
      >>> _parsealiasdecl('foo bar')
      ('foo bar', None, None, 'at 4: invalid token')
      >>> _parsealiasdecl('foo()')
      ('foo', ('func', ('symbol', 'foo')), [], None)
      >>> _parsealiasdecl('$foo()')
      ('$foo()', None, None, "'$' not for alias arguments")
      >>> _parsealiasdecl('foo($1, $2)')
      ('foo', ('func', ('symbol', 'foo')), ['$1', '$2'], None)
      >>> _parsealiasdecl('foo(bar_bar, baz.baz)')
      ('foo', ('func', ('symbol', 'foo')), ['bar_bar', 'baz.baz'], None)
      >>> _parsealiasdecl('foo($1, $2, nested($1, $2))')
      ('foo($1, $2, nested($1, $2))', None, None, 'invalid argument list')
      >>> _parsealiasdecl('foo(bar($1, $2))')
      ('foo(bar($1, $2))', None, None, 'invalid argument list')
      >>> _parsealiasdecl('foo("string")')
      ('foo("string")', None, None, 'invalid argument list')
      >>> _parsealiasdecl('foo($1, $2')
      ('foo($1, $2', None, None, 'at 10: unexpected token: end')
      >>> _parsealiasdecl('foo("string')
      ('foo("string', None, None, 'at 5: unterminated string')
      >>> _parsealiasdecl('foo($1, $2, $1)')
      ('foo', None, None, 'argument names collide with each other')
      """
      p = parser.parser(_tokenizealias, elements)
      try:
          tree, pos = p.parse(decl)
          if (pos != len(decl)):
              raise error.ParseError(_('invalid token'), pos)
  
          if isvalidsymbol(tree):
              # "name = ...." style
              name = getsymbol(tree)
              if name.startswith('$'):
                  return (decl, None, None, _("'$' not for alias arguments"))
              return (name, ('symbol', name), None, None)
  
          if isvalidfunc(tree):
              # "name(arg, ....) = ...." style
              name = getfuncname(tree)
              if name.startswith('$'):
                  return (decl, None, None, _("'$' not for alias arguments"))
              args = []
              for arg in getfuncargs(tree):
                  if not isvalidsymbol(arg):
                      return (decl, None, None, _("invalid argument list"))
                  args.append(getsymbol(arg))
              if len(args) != len(set(args)):
                  return (name, None, None,
                          _("argument names collide with each other"))
              return (name, ('func', ('symbol', name)), args, None)
  
          return (decl, None, None, _("invalid format"))
      except error.ParseError, inst:
          return (decl, None, None, parseerrordetail(inst))
  
  def _parsealiasdefn(defn, args):
      """Parse alias definition ``defn``
  
      This function also replaces alias argument references in the
      specified definition by ``_aliasarg(ARGNAME)``.
  
      ``args`` is a list of alias argument names, or None if the alias
      is declared as a symbol.
  
      This returns "tree" as parsing result.
  
      >>> args = ['$1', '$2', 'foo']
      >>> print prettyformat(_parsealiasdefn('$1 or foo', args))
      (or
        (func
          ('symbol', '_aliasarg')
          ('string', '$1'))
        (func
          ('symbol', '_aliasarg')
          ('string', 'foo')))
      >>> try:
      ...     _parsealiasdefn('$1 or $bar', args)
      ... except error.ParseError, inst:
      ...     print parseerrordetail(inst)
      at 6: '$' not for alias arguments
      >>> args = ['$1', '$10', 'foo']
      >>> print prettyformat(_parsealiasdefn('$10 or foobar', args))
      (or
        (func
          ('symbol', '_aliasarg')
          ('string', '$10'))
        ('symbol', 'foobar'))
      >>> print prettyformat(_parsealiasdefn('"$1" or "foo"', args))
      (or
        ('string', '$1')
        ('string', 'foo'))
      """
      def tokenizedefn(program, lookup=None):
          if args:
              argset = set(args)
          else:
              argset = set()
  
          for t, value, pos in _tokenizealias(program, lookup=lookup):
              if t == 'symbol':
                  if value in argset:
                      # emulate tokenization of "_aliasarg('ARGNAME')":
                      # "_aliasarg()" is an unknown symbol only used separate
                      # alias argument placeholders from regular strings.
                      yield ('symbol', '_aliasarg', pos)
                      yield ('(', None, pos)
                      yield ('string', value, pos)
                      yield (')', None, pos)
                      continue
                  elif value.startswith('$'):
                      raise error.ParseError(_("'$' not for alias arguments"),
                                             pos)
              yield (t, value, pos)
  
      p = parser.parser(tokenizedefn, elements)
      tree, pos = p.parse(defn)
      if pos != len(defn):
          raise error.ParseError(_('invalid token'), pos)
      return tree
  
  class revsetalias(object):
      # whether own `error` information is already shown or not.
      # this avoids showing same warning multiple times at each `findaliases`.
      warned = False
  
      def __init__(self, name, value):
          '''Aliases like:
  
          h = heads(default)
          b($1) = ancestors($1) - ancestors(default)
          '''
          self.name, self.tree, self.args, self.error = _parsealiasdecl(name)
          if self.error:
              self.error = _('failed to parse the declaration of revset alias'
                             ' "%s": %s') % (self.name, self.error)
              return
  
          try:
              self.replacement = _parsealiasdefn(value, self.args)
              # Check for placeholder injection
              _checkaliasarg(self.replacement, self.args)
          except error.ParseError, inst:
              self.error = _('failed to parse the definition of revset alias'
                             ' "%s": %s') % (self.name, parseerrordetail(inst))
  
  def _getalias(aliases, tree):
      """If tree looks like an unexpanded alias, return it. Return None
      otherwise.
      """
      if isinstance(tree, tuple) and tree:
          if tree[0] == 'symbol' and len(tree) == 2:
              name = tree[1]
              alias = aliases.get(name)
              if alias and alias.args is None and alias.tree == tree:
                  return alias
          if tree[0] == 'func' and len(tree) > 1:
              if tree[1][0] == 'symbol' and len(tree[1]) == 2:
                  name = tree[1][1]
                  alias = aliases.get(name)
                  if alias and alias.args is not None and alias.tree == tree[:2]:
                      return alias
      return None
  
  def _expandargs(tree, args):
      """Replace _aliasarg instances with the substitution value of the
      same name in args, recursively.
      """
      if not tree or not isinstance(tree, tuple):
          return tree
      arg = _getaliasarg(tree)
      if arg is not None:
          return args[arg]
      return tuple(_expandargs(t, args) for t in tree)
  
  def _expandaliases(aliases, tree, expanding, cache):
      """Expand aliases in tree, recursively.
  
      'aliases' is a dictionary mapping user defined aliases to
      revsetalias objects.
      """
      if not isinstance(tree, tuple):
          # Do not expand raw strings
          return tree
      alias = _getalias(aliases, tree)
      if alias is not None:
          if alias.error:
              raise util.Abort(alias.error)
          if alias in expanding:
              raise error.ParseError(_('infinite expansion of revset alias "%s" '
                                       'detected') % alias.name)
          expanding.append(alias)
          if alias.name not in cache:
              cache[alias.name] = _expandaliases(aliases, alias.replacement,
                                                 expanding, cache)
          result = cache[alias.name]
          expanding.pop()
          if alias.args is not None:
              l = getlist(tree[2])
              if len(l) != len(alias.args):
                  raise error.ParseError(
                      _('invalid number of arguments: %s') % len(l))
              l = [_expandaliases(aliases, a, [], cache) for a in l]
              result = _expandargs(result, dict(zip(alias.args, l)))
      else:
          result = tuple(_expandaliases(aliases, t, expanding, cache)
                         for t in tree)
      return result
  
  def findaliases(ui, tree, showwarning=None):
      _checkaliasarg(tree)
      aliases = {}
      for k, v in ui.configitems('revsetalias'):
          alias = revsetalias(k, v)
          aliases[alias.name] = alias
      tree = _expandaliases(aliases, tree, [], {})
      if showwarning:
          # warn about problematic (but not referred) aliases
          for name, alias in sorted(aliases.iteritems()):
              if alias.error and not alias.warned:
                  showwarning(_('warning: %s\n') % (alias.error))
                  alias.warned = True
      return tree
  
  def foldconcat(tree):
      """Fold elements to be concatenated by `##`
      """
      if not isinstance(tree, tuple) or tree[0] in ('string', 'symbol'):
          return tree
      if tree[0] == '_concat':
          pending = [tree]
          l = []
          while pending:
              e = pending.pop()
              if e[0] == '_concat':
                  pending.extend(reversed(e[1:]))
              elif e[0] in ('string', 'symbol'):
                  l.append(e[1])
              else:
                  msg = _("\"##\" can't concatenate \"%s\" element") % (e[0])
                  raise error.ParseError(msg)
          return ('string', ''.join(l))
      else:
          return tuple(foldconcat(t) for t in tree)
  
  def parse(spec, lookup=None):
      p = parser.parser(tokenize, elements)
      return p.parse(spec, lookup=lookup)
  
  def posttreebuilthook(tree, repo):
      # hook for extensions to execute code on the optimized tree
      pass
  
  def match(ui, spec, repo=None):
      if not spec:
          raise error.ParseError(_("empty query"))
      lookup = None
      if repo:
          lookup = repo.__contains__
      tree, pos = parse(spec, lookup)
      if (pos != len(spec)):
          raise error.ParseError(_("invalid token"), pos)
      if ui:
          tree = findaliases(ui, tree, showwarning=ui.warn)
      tree = foldconcat(tree)
      weight, tree = optimize(tree, True)
      posttreebuilthook(tree, repo)
      def mfunc(repo, subset=None):
          if subset is None:
              subset = fullreposet(repo)
          if util.safehasattr(subset, 'isascending'):
              result = getset(repo, subset, tree)
          else:
              result = getset(repo, baseset(subset), tree)
          return result
      return mfunc
  
  def formatspec(expr, *args):
      '''
      This is a convenience function for using revsets internally, and
      escapes arguments appropriately. Aliases are intentionally ignored
      so that intended expression behavior isn't accidentally subverted.
  
      Supported arguments:
  
      %r = revset expression, parenthesized
      %d = int(arg), no quoting
      %s = string(arg), escaped and single-quoted
      %b = arg.branch(), escaped and single-quoted
      %n = hex(arg), single-quoted
      %% = a literal '%'
  
      Prefixing the type with 'l' specifies a parenthesized list of that type.
  
      >>> formatspec('%r:: and %lr', '10 or 11', ("this()", "that()"))
      '(10 or 11):: and ((this()) or (that()))'
      >>> formatspec('%d:: and not %d::', 10, 20)
      '10:: and not 20::'
      >>> formatspec('%ld or %ld', [], [1])
      "_list('') or 1"
      >>> formatspec('keyword(%s)', 'foo\\xe9')
      "keyword('foo\\\\xe9')"
      >>> b = lambda: 'default'
      >>> b.branch = b
      >>> formatspec('branch(%b)', b)
      "branch('default')"
      >>> formatspec('root(%ls)', ['a', 'b', 'c', 'd'])
      "root(_list('a\\x00b\\x00c\\x00d'))"
      '''
  
      def quote(s):
          return repr(str(s))
  
      def argtype(c, arg):
          if c == 'd':
              return str(int(arg))
          elif c == 's':
              return quote(arg)
          elif c == 'r':
              parse(arg) # make sure syntax errors are confined
              return '(%s)' % arg
          elif c == 'n':
              return quote(node.hex(arg))
          elif c == 'b':
              return quote(arg.branch())
  
      def listexp(s, t):
          l = len(s)
          if l == 0:
              return "_list('')"
          elif l == 1:
              return argtype(t, s[0])
          elif t == 'd':
              return "_intlist('%s')" % "\0".join(str(int(a)) for a in s)
          elif t == 's':
              return "_list('%s')" % "\0".join(s)
          elif t == 'n':
              return "_hexlist('%s')" % "\0".join(node.hex(a) for a in s)
          elif t == 'b':
              return "_list('%s')" % "\0".join(a.branch() for a in s)
  
          m = l // 2
          return '(%s or %s)' % (listexp(s[:m], t), listexp(s[m:], t))
  
      ret = ''
      pos = 0
      arg = 0
      while pos < len(expr):
          c = expr[pos]
          if c == '%':
              pos += 1
              d = expr[pos]
              if d == '%':
                  ret += d
              elif d in 'dsnbr':
                  ret += argtype(d, args[arg])
                  arg += 1
              elif d == 'l':
                  # a list of some type
                  pos += 1
                  d = expr[pos]
                  ret += listexp(list(args[arg]), d)
                  arg += 1
              else:
                  raise util.Abort('unexpected revspec format character %s' % d)
          else:
              ret += c
          pos += 1
  
      return ret
  
  def prettyformat(tree):
      def _prettyformat(tree, level, lines):
          if not isinstance(tree, tuple) or tree[0] in ('string', 'symbol'):
              lines.append((level, str(tree)))
          else:
              lines.append((level, '(%s' % tree[0]))
              for s in tree[1:]:
                  _prettyformat(s, level + 1, lines)
              lines[-1:] = [(lines[-1][0], lines[-1][1] + ')')]
  
      lines = []
      _prettyformat(tree, 0, lines)
      output = '\n'.join(('  '*l + s) for l, s in lines)
      return output
  
  def depth(tree):
      if isinstance(tree, tuple):
          return max(map(depth, tree)) + 1
      else:
          return 0
  
  def funcsused(tree):
      if not isinstance(tree, tuple) or tree[0] in ('string', 'symbol'):
          return set()
      else:
          funcs = set()
          for s in tree[1:]:
              funcs |= funcsused(s)
          if tree[0] == 'func':
              funcs.add(tree[1][1])
          return funcs
  
  class abstractsmartset(object):
  
      def __nonzero__(self):
          """True if the smartset is not empty"""
          raise NotImplementedError()
  
      def __contains__(self, rev):
          """provide fast membership testing"""
          raise NotImplementedError()
  
      def __iter__(self):
          """iterate the set in the order it is supposed to be iterated"""
          raise NotImplementedError()
  
      # Attributes containing a function to perform a fast iteration in a given
      # direction. A smartset can have none, one, or both defined.
      #
      # Default value is None instead of a function returning None to avoid
      # initializing an iterator just for testing if a fast method exists.
      fastasc = None
      fastdesc = None
  
      def isascending(self):
          """True if the set will iterate in ascending order"""
          raise NotImplementedError()
  
      def isdescending(self):
          """True if the set will iterate in descending order"""
          raise NotImplementedError()
  
      def min(self):
          """return the minimum element in the set"""
          if self.fastasc is not None:
              for r in self.fastasc():
                  return r
              raise ValueError('arg is an empty sequence')
          return min(self)
  
      def max(self):
          """return the maximum element in the set"""
          if self.fastdesc is not None:
              for r in self.fastdesc():
                  return r
              raise ValueError('arg is an empty sequence')
          return max(self)
  
      def first(self):
          """return the first element in the set (user iteration perspective)
  
          Return None if the set is empty"""
          raise NotImplementedError()
  
      def last(self):
          """return the last element in the set (user iteration perspective)
  
          Return None if the set is empty"""
          raise NotImplementedError()
  
      def __len__(self):
          """return the length of the smartsets
  
          This can be expensive on smartset that could be lazy otherwise."""
          raise NotImplementedError()
  
      def reverse(self):
          """reverse the expected iteration order"""
          raise NotImplementedError()
  
      def sort(self, reverse=True):
          """get the set to iterate in an ascending or descending order"""
          raise NotImplementedError()
  
      def __and__(self, other):
          """Returns a new object with the intersection of the two collections.
  
          This is part of the mandatory API for smartset."""
          if isinstance(other, fullreposet):
              return self
          return self.filter(other.__contains__, cache=False)
  
      def __add__(self, other):
          """Returns a new object with the union of the two collections.
  
          This is part of the mandatory API for smartset."""
          return addset(self, other)
  
      def __sub__(self, other):
          """Returns a new object with the substraction of the two collections.
  
          This is part of the mandatory API for smartset."""
          c = other.__contains__
          return self.filter(lambda r: not c(r), cache=False)
  
      def filter(self, condition, cache=True):
          """Returns this smartset filtered by condition as a new smartset.
  
          `condition` is a callable which takes a revision number and returns a
          boolean.
  
          This is part of the mandatory API for smartset."""
          # builtin cannot be cached. but do not needs to
          if cache and util.safehasattr(condition, 'func_code'):
              condition = util.cachefunc(condition)
          return filteredset(self, condition)
  
  class baseset(abstractsmartset):
      """Basic data structure that represents a revset and contains the basic
      operation that it should be able to perform.
  
      Every method in this class should be implemented by any smartset class.
      """
      def __init__(self, data=()):
          if not isinstance(data, list):
              data = list(data)
          self._list = data
          self._ascending = None
  
      @util.propertycache
      def _set(self):
          return set(self._list)
  
      @util.propertycache
      def _asclist(self):
          asclist = self._list[:]
          asclist.sort()
          return asclist
  
      def __iter__(self):
          if self._ascending is None:
              return iter(self._list)
          elif self._ascending:
              return iter(self._asclist)
          else:
              return reversed(self._asclist)
  
      def fastasc(self):
          return iter(self._asclist)
  
      def fastdesc(self):
          return reversed(self._asclist)
  
      @util.propertycache
      def __contains__(self):
          return self._set.__contains__
  
      def __nonzero__(self):
          return bool(self._list)
  
      def sort(self, reverse=False):
          self._ascending = not bool(reverse)
  
      def reverse(self):
          if self._ascending is None:
              self._list.reverse()
          else:
              self._ascending = not self._ascending
  
      def __len__(self):
          return len(self._list)
  
      def isascending(self):
          """Returns True if the collection is ascending order, False if not.
  
          This is part of the mandatory API for smartset."""
          if len(self) <= 1:
              return True
          return self._ascending is not None and self._ascending
  
      def isdescending(self):
          """Returns True if the collection is descending order, False if not.
  
          This is part of the mandatory API for smartset."""
          if len(self) <= 1:
              return True
          return self._ascending is not None and not self._ascending
  
      def first(self):
          if self:
              if self._ascending is None:
                  return self._list[0]
              elif self._ascending:
                  return self._asclist[0]
              else:
                  return self._asclist[-1]
          return None
  
      def last(self):
          if self:
              if self._ascending is None:
                  return self._list[-1]
              elif self._ascending:
                  return self._asclist[-1]
              else:
                  return self._asclist[0]
          return None
  
      def __repr__(self):
          d = {None: '', False: '-', True: '+'}[self._ascending]
          return '<%s%s %r>' % (type(self).__name__, d, self._list)
  
  class filteredset(abstractsmartset):
      """Duck type for baseset class which iterates lazily over the revisions in
      the subset and contains a function which tests for membership in the
      revset
      """
      def __init__(self, subset, condition=lambda x: True):
          """
          condition: a function that decide whether a revision in the subset
                     belongs to the revset or not.
          """
          self._subset = subset
          self._condition = condition
          self._cache = {}
  
      def __contains__(self, x):
          c = self._cache
          if x not in c:
              v = c[x] = x in self._subset and self._condition(x)
              return v
          return c[x]
  
      def __iter__(self):
          return self._iterfilter(self._subset)
  
      def _iterfilter(self, it):
          cond = self._condition
          for x in it:
              if cond(x):
                  yield x
  
      @property
      def fastasc(self):
          it = self._subset.fastasc
          if it is None:
              return None
          return lambda: self._iterfilter(it())
  
      @property
      def fastdesc(self):
          it = self._subset.fastdesc
          if it is None:
              return None
          return lambda: self._iterfilter(it())
  
      def __nonzero__(self):
          for r in self:
              return True
          return False
  
      def __len__(self):
          # Basic implementation to be changed in future patches.
          l = baseset([r for r in self])
          return len(l)
  
      def sort(self, reverse=False):
          self._subset.sort(reverse=reverse)
  
      def reverse(self):
          self._subset.reverse()
  
      def isascending(self):
          return self._subset.isascending()
  
      def isdescending(self):
          return self._subset.isdescending()
  
      def first(self):
          for x in self:
              return x
          return None
  
      def last(self):
          it = None
          if self._subset.isascending:
              it = self.fastdesc
          elif self._subset.isdescending:
              it = self.fastdesc
          if it is None:
              # slowly consume everything. This needs improvement
              it = lambda: reversed(list(self))
          for x in it():
              return x
          return None
  
      def __repr__(self):
          return '<%s %r>' % (type(self).__name__, self._subset)
  
  class addset(abstractsmartset):
      """Represent the addition of two sets
  
      Wrapper structure for lazily adding two structures without losing much
      performance on the __contains__ method
  
      If the ascending attribute is set, that means the two structures are
      ordered in either an ascending or descending way. Therefore, we can add
      them maintaining the order by iterating over both at the same time
      """
      def __init__(self, revs1, revs2, ascending=None):
          self._r1 = revs1
          self._r2 = revs2
          self._iter = None
          self._ascending = ascending
          self._genlist = None
          self._asclist = None
  
      def __len__(self):
          return len(self._list)
  
      def __nonzero__(self):
          return bool(self._r1) or bool(self._r2)
  
      @util.propertycache
      def _list(self):
          if not self._genlist:
              self._genlist = baseset(self._iterator())
          return self._genlist
  
      def _iterator(self):
          """Iterate over both collections without repeating elements
  
          If the ascending attribute is not set, iterate over the first one and
          then over the second one checking for membership on the first one so we
          dont yield any duplicates.
  
          If the ascending attribute is set, iterate over both collections at the
          same time, yielding only one value at a time in the given order.
          """
          if self._ascending is None:
              def gen():
                  for r in self._r1:
                      yield r
                  inr1 = self._r1.__contains__
                  for r in self._r2:
                      if not inr1(r):
                          yield r
              gen = gen()
          else:
              iter1 = iter(self._r1)
              iter2 = iter(self._r2)
              gen = self._iterordered(self._ascending, iter1, iter2)
          return gen
  
      def __iter__(self):
          if self._ascending is None:
              if self._genlist:
                  return iter(self._genlist)
              return iter(self._iterator())
          self._trysetasclist()
          if self._ascending:
              it = self.fastasc
          else:
              it = self.fastdesc
          if it is None:
              # consume the gen and try again
              self._list
              return iter(self)
          return it()
  
      def _trysetasclist(self):
          """populate the _asclist attribute if possible and necessary"""
          if self._genlist is not None and self._asclist is None:
              self._asclist = sorted(self._genlist)
  
      @property
      def fastasc(self):
          self._trysetasclist()
          if self._asclist is not None:
              return self._asclist.__iter__
          iter1 = self._r1.fastasc
          iter2 = self._r2.fastasc
          if None in (iter1, iter2):
              return None
          return lambda: self._iterordered(True, iter1(), iter2())
  
      @property
      def fastdesc(self):
          self._trysetasclist()
          if self._asclist is not None:
              return self._asclist.__reversed__
          iter1 = self._r1.fastdesc
          iter2 = self._r2.fastdesc
          if None in (iter1, iter2):
              return None
          return lambda: self._iterordered(False, iter1(), iter2())
  
      def _iterordered(self, ascending, iter1, iter2):
          """produce an ordered iteration from two iterators with the same order
  
          The ascending is used to indicated the iteration direction.
          """
          choice = max
          if ascending:
              choice = min
  
          val1 = None
          val2 = None
  
          choice = max
          if ascending:
              choice = min
          try:
              # Consume both iterators in an ordered way until one is
              # empty
              while True:
                  if val1 is None:
                      val1 = iter1.next()
                  if val2 is None:
                      val2 = iter2.next()
                  next = choice(val1, val2)
                  yield next
                  if val1 == next:
                      val1 = None
                  if val2 == next:
                      val2 = None
          except StopIteration:
              # Flush any remaining values and consume the other one
              it = iter2
              if val1 is not None:
                  yield val1
                  it = iter1
              elif val2 is not None:
                  # might have been equality and both are empty
                  yield val2
              for val in it:
                  yield val
  
      def __contains__(self, x):
          return x in self._r1 or x in self._r2
  
      def sort(self, reverse=False):
          """Sort the added set
  
          For this we use the cached list with all the generated values and if we
          know they are ascending or descending we can sort them in a smart way.
          """
          self._ascending = not reverse
  
      def isascending(self):
          return self._ascending is not None and self._ascending
  
      def isdescending(self):
          return self._ascending is not None and not self._ascending
  
      def reverse(self):
          if self._ascending is None:
              self._list.reverse()
          else:
              self._ascending = not self._ascending
  
      def first(self):
          for x in self:
              return x
          return None
  
      def last(self):
          self.reverse()
          val = self.first()
          self.reverse()
          return val
  
      def __repr__(self):
          d = {None: '', False: '-', True: '+'}[self._ascending]
          return '<%s%s %r, %r>' % (type(self).__name__, d, self._r1, self._r2)
  
  class generatorset(abstractsmartset):
      """Wrap a generator for lazy iteration
  
      Wrapper structure for generators that provides lazy membership and can
      be iterated more than once.
      When asked for membership it generates values until either it finds the
      requested one or has gone through all the elements in the generator
      """
      def __init__(self, gen, iterasc=None):
          """
          gen: a generator producing the values for the generatorset.
          """
          self._gen = gen
          self._asclist = None
          self._cache = {}
          self._genlist = []
          self._finished = False
          self._ascending = True
          if iterasc is not None:
              if iterasc:
                  self.fastasc = self._iterator
                  self.__contains__ = self._asccontains
              else:
                  self.fastdesc = self._iterator
                  self.__contains__ = self._desccontains
  
      def __nonzero__(self):
          for r in self:
              return True
          return False
  
      def __contains__(self, x):
          if x in self._cache:
              return self._cache[x]
  
          # Use new values only, as existing values would be cached.
          for l in self._consumegen():
              if l == x:
                  return True
  
          self._cache[x] = False
          return False
  
      def _asccontains(self, x):
          """version of contains optimised for ascending generator"""
          if x in self._cache:
              return self._cache[x]
  
          # Use new values only, as existing values would be cached.
          for l in self._consumegen():
              if l == x:
                  return True
              if l > x:
                  break
  
          self._cache[x] = False
          return False
  
      def _desccontains(self, x):
          """version of contains optimised for descending generator"""
          if x in self._cache:
              return self._cache[x]
  
          # Use new values only, as existing values would be cached.
          for l in self._consumegen():
              if l == x:
                  return True
              if l < x:
                  break
  
          self._cache[x] = False
          return False
  
      def __iter__(self):
          if self._ascending:
              it = self.fastasc
          else:
              it = self.fastdesc
          if it is not None:
              return it()
          # we need to consume the iterator
          for x in self._consumegen():
              pass
          # recall the same code
          return iter(self)
  
      def _iterator(self):
          if self._finished:
              return iter(self._genlist)
  
          # We have to use this complex iteration strategy to allow multiple
          # iterations at the same time. We need to be able to catch revision
          # removed from _consumegen and added to genlist in another instance.
          #
          # Getting rid of it would provide an about 15% speed up on this
          # iteration.
          genlist = self._genlist
          nextrev = self._consumegen().next
          _len = len # cache global lookup
          def gen():
              i = 0
              while True:
                  if i < _len(genlist):
                      yield genlist[i]
                  else:
                      yield nextrev()
                  i += 1
          return gen()
  
      def _consumegen(self):
          cache = self._cache
          genlist = self._genlist.append
          for item in self._gen:
              cache[item] = True
              genlist(item)
              yield item
          if not self._finished:
              self._finished = True
              asc = self._genlist[:]
              asc.sort()
              self._asclist = asc
              self.fastasc = asc.__iter__
              self.fastdesc = asc.__reversed__
  
      def __len__(self):
          for x in self._consumegen():
              pass
          return len(self._genlist)
  
      def sort(self, reverse=False):
          self._ascending = not reverse
  
      def reverse(self):
          self._ascending = not self._ascending
  
      def isascending(self):
          return self._ascending
  
      def isdescending(self):
          return not self._ascending
  
      def first(self):
          if self._ascending:
              it = self.fastasc
          else:
              it = self.fastdesc
          if it is None:
              # we need to consume all and try again
              for x in self._consumegen():
                  pass
              return self.first()
          if self:
              return it().next()
          return None
  
      def last(self):
          if self._ascending:
              it = self.fastdesc
          else:
              it = self.fastasc
          if it is None:
              # we need to consume all and try again
              for x in self._consumegen():
                  pass
              return self.first()
          if self:
              return it().next()
          return None
  
      def __repr__(self):
          d = {False: '-', True: '+'}[self._ascending]
          return '<%s%s>' % (type(self).__name__, d)
  
  class spanset(abstractsmartset):
      """Duck type for baseset class which represents a range of revisions and
      can work lazily and without having all the range in memory
  
      Note that spanset(x, y) behave almost like xrange(x, y) except for two
      notable points:
      - when x < y it will be automatically descending,
      - revision filtered with this repoview will be skipped.
  
      """
      def __init__(self, repo, start=0, end=None):
          """
          start: first revision included the set
                 (default to 0)
          end:   first revision excluded (last+1)
                 (default to len(repo)
  
          Spanset will be descending if `end` < `start`.
          """
          if end is None:
              end = len(repo)
          self._ascending = start <= end
          if not self._ascending:
              start, end = end + 1, start +1
          self._start = start
          self._end = end
          self._hiddenrevs = repo.changelog.filteredrevs
  
      def sort(self, reverse=False):
          self._ascending = not reverse
  
      def reverse(self):
          self._ascending = not self._ascending
  
      def _iterfilter(self, iterrange):
          s = self._hiddenrevs
          for r in iterrange:
              if r not in s:
                  yield r
  
      def __iter__(self):
          if self._ascending:
              return self.fastasc()
          else:
              return self.fastdesc()
  
      def fastasc(self):
          iterrange = xrange(self._start, self._end)
          if self._hiddenrevs:
              return self._iterfilter(iterrange)
          return iter(iterrange)
  
      def fastdesc(self):
          iterrange = xrange(self._end - 1, self._start - 1, -1)
          if self._hiddenrevs:
              return self._iterfilter(iterrange)
          return iter(iterrange)
  
      def __contains__(self, rev):
          hidden = self._hiddenrevs
          return ((self._start <= rev < self._end)
                  and not (hidden and rev in hidden))
  
      def __nonzero__(self):
          for r in self:
              return True
          return False
  
      def __len__(self):
          if not self._hiddenrevs:
              return abs(self._end - self._start)
          else:
              count = 0
              start = self._start
              end = self._end
              for rev in self._hiddenrevs:
                  if (end < rev <= start) or (start <= rev < end):
                      count += 1
              return abs(self._end - self._start) - count
  
      def isascending(self):
          return self._ascending
  
      def isdescending(self):
          return not self._ascending
  
      def first(self):
          if self._ascending:
              it = self.fastasc
          else:
              it = self.fastdesc
          for x in it():
              return x
          return None
  
      def last(self):
          if self._ascending:
              it = self.fastdesc
          else:
              it = self.fastasc
          for x in it():
              return x
          return None
  
      def __repr__(self):
          d = {False: '-', True: '+'}[self._ascending]
          return '<%s%s %d:%d>' % (type(self).__name__, d,
                                   self._start, self._end - 1)
  
  class fullreposet(spanset):
      """a set containing all revisions in the repo
  
      This class exists to host special optimization and magic to handle virtual
      revisions such as "null".
      """
  
      def __init__(self, repo):
          super(fullreposet, self).__init__(repo)
  
      def __and__(self, other):
          """As self contains the whole repo, all of the other set should also be
          in self. Therefore `self & other = other`.
  
          This boldly assumes the other contains valid revs only.
          """
          # other not a smartset, make is so
          if not util.safehasattr(other, 'isascending'):
              # filter out hidden revision
              # (this boldly assumes all smartset are pure)
              #
              # `other` was used with "&", let's assume this is a set like
              # object.
              other = baseset(other - self._hiddenrevs)
  
          other.sort(reverse=self.isdescending())
          return other
  
  def prettyformatset(revs):
      lines = []
      rs = repr(revs)
      p = 0
      while p < len(rs):
          q = rs.find('<', p + 1)
          if q < 0:
              q = len(rs)
          l = rs.count('<', 0, p) - rs.count('>', 0, p)
          assert l >= 0
          lines.append((l, rs[p:q].rstrip()))
          p = q
      return '\n'.join('  ' * l + s for l, s in lines)
  
  # tell hggettext to extract docstrings from these functions:
  i18nfunctions = symbols.values()
  