[PATCH 2 of 3] revset: split language services to revsetlang module (API)

Yuya Nishihara yuya at tcha.org
Sun Feb 19 08:12:05 EST 2017


# HG changeset patch
# User Yuya Nishihara <yuya at tcha.org>
# Date 1487495973 -32400
#      Sun Feb 19 18:19:33 2017 +0900
# Node ID 85ab530251b2810e18339c13a0f95a4f02d7ab3a
# Parent  211cf331f8cf94d8fa1d2324f7cee5047124e8e6
revset: split language services to revsetlang module (API)

New revsetlang module hosts parser, tokenizer, and miscellaneous functions
working on parsed tree. It does not include functions for evaluation such as
getset() and match().

  2288 mercurial/revset.py
   684 mercurial/revsetlang.py
  2972 total

get*() functions are aliased since they are common in revset.py.

diff --git a/hgext/mq.py b/hgext/mq.py
--- a/hgext/mq.py
+++ b/hgext/mq.py
@@ -89,7 +89,7 @@ from mercurial import (
     phases,
     pycompat,
     registrar,
-    revset,
+    revsetlang,
     scmutil,
     smartset,
     subrepo,
@@ -3568,7 +3568,7 @@ revsetpredicate = registrar.revsetpredic
 def revsetmq(repo, subset, x):
     """Changesets managed by MQ.
     """
-    revset.getargs(x, 0, 0, _("mq takes no arguments"))
+    revsetlang.getargs(x, 0, 0, _("mq takes no arguments"))
     applied = set([repo[r.node].rev() for r in repo.mq.applied])
     return smartset.baseset([r for r in subset if r in applied])
 
diff --git a/mercurial/commands.py b/mercurial/commands.py
--- a/mercurial/commands.py
+++ b/mercurial/commands.py
@@ -44,7 +44,7 @@ from . import (
     patch,
     phases,
     pycompat,
-    revset,
+    revsetlang,
     scmutil,
     server,
     sshserver,
@@ -3414,7 +3414,7 @@ def log(ui, repo, *pats, **opts):
 
     """
     if opts.get('follow') and opts.get('rev'):
-        opts['rev'] = [revset.formatspec('reverse(::%lr)', opts.get('rev'))]
+        opts['rev'] = [revsetlang.formatspec('reverse(::%lr)', opts.get('rev'))]
         del opts['follow']
 
     if opts.get('graph'):
@@ -4093,7 +4093,7 @@ def push(ui, repo, dest=None, **opts):
     elif path.pushrev:
         # It doesn't make any sense to specify ancestor revisions. So limit
         # to DAG heads to make discovery simpler.
-        expr = revset.formatspec('heads(%r)', path.pushrev)
+        expr = revsetlang.formatspec('heads(%r)', path.pushrev)
         revs = scmutil.revrange(repo, [expr])
         revs = [repo[rev].node() for rev in revs]
         if not revs:
diff --git a/mercurial/debugcommands.py b/mercurial/debugcommands.py
--- a/mercurial/debugcommands.py
+++ b/mercurial/debugcommands.py
@@ -52,6 +52,7 @@ from . import (
     repair,
     revlog,
     revset,
+    revsetlang,
     scmutil,
     setdiscovery,
     simplemerge,
@@ -1794,10 +1795,10 @@ def debugrevspec(ui, repo, expr, **opts)
     """
     stages = [
         ('parsed', lambda tree: tree),
-        ('expanded', lambda tree: revset.expandaliases(ui, tree)),
-        ('concatenated', revset.foldconcat),
-        ('analyzed', revset.analyze),
-        ('optimized', revset.optimize),
+        ('expanded', lambda tree: revsetlang.expandaliases(ui, tree)),
+        ('concatenated', revsetlang.foldconcat),
+        ('analyzed', revsetlang.analyze),
+        ('optimized', revsetlang.optimize),
     ]
     if opts['no_optimized']:
         stages = stages[:-1]
@@ -1826,13 +1827,13 @@ def debugrevspec(ui, repo, expr, **opts)
 
     treebystage = {}
     printedtree = None
-    tree = revset.parse(expr, lookup=repo.__contains__)
+    tree = revsetlang.parse(expr, lookup=repo.__contains__)
     for n, f in stages:
         treebystage[n] = tree = f(tree)
         if n in showalways or (n in showchanged and tree != printedtree):
             if opts['show_stage'] or n != 'parsed':
                 ui.write(("* %s:\n") % n)
-            ui.write(revset.prettyformat(tree), "\n")
+            ui.write(revsetlang.prettyformat(tree), "\n")
             printedtree = tree
 
     if opts['verify_optimized']:
diff --git a/mercurial/hgweb/webcommands.py b/mercurial/hgweb/webcommands.py
--- a/mercurial/hgweb/webcommands.py
+++ b/mercurial/hgweb/webcommands.py
@@ -32,6 +32,7 @@ from .. import (
     error,
     graphmod,
     revset,
+    revsetlang,
     scmutil,
     smartset,
     templatefilters,
@@ -239,20 +240,20 @@ def _search(web, req, tmpl):
 
         revdef = 'reverse(%s)' % query
         try:
-            tree = revset.parse(revdef)
+            tree = revsetlang.parse(revdef)
         except error.ParseError:
             # can't parse to a revset tree
             return MODE_KEYWORD, query
 
-        if revset.depth(tree) <= 2:
+        if revsetlang.depth(tree) <= 2:
             # no revset syntax used
             return MODE_KEYWORD, query
 
         if any((token, (value or '')[:3]) == ('string', 're:')
-                    for token, value, pos in revset.tokenize(revdef)):
+               for token, value, pos in revsetlang.tokenize(revdef)):
             return MODE_KEYWORD, query
 
-        funcsused = revset.funcsused(tree)
+        funcsused = revsetlang.funcsused(tree)
         if not funcsused.issubset(revset.safesymbols):
             return MODE_KEYWORD, query
 
diff --git a/mercurial/localrepo.py b/mercurial/localrepo.py
--- a/mercurial/localrepo.py
+++ b/mercurial/localrepo.py
@@ -50,6 +50,7 @@ from . import (
     pushkey,
     repoview,
     revset,
+    revsetlang,
     scmutil,
     store,
     subrepo,
@@ -573,7 +574,7 @@ class localrepository(object):
         '''Find revisions matching a revset.
 
         The revset is specified as a string ``expr`` that may contain
-        %-formatting to escape certain types. See ``revset.formatspec``.
+        %-formatting to escape certain types. See ``revsetlang.formatspec``.
 
         Revset aliases from the configuration are not expanded. To expand
         user aliases, consider calling ``scmutil.revrange()``.
@@ -581,7 +582,7 @@ class localrepository(object):
         Returns a revset.abstractsmartset, which is a list-like interface
         that contains integer revisions.
         '''
-        expr = revset.formatspec(expr, *args)
+        expr = revsetlang.formatspec(expr, *args)
         m = revset.match(None, expr)
         return m(self)
 
diff --git a/mercurial/revset.py b/mercurial/revset.py
--- a/mercurial/revset.py
+++ b/mercurial/revset.py
@@ -9,7 +9,6 @@ from __future__ import absolute_import
 
 import heapq
 import re
-import string
 
 from .i18n import _
 from . import (
@@ -20,16 +19,29 @@ from . import (
     match as matchmod,
     node,
     obsolete as obsmod,
-    parser,
     pathutil,
     phases,
-    pycompat,
     registrar,
     repoview,
+    revsetlang,
     smartset,
     util,
 )
 
+# helpers for processing parsed tree
+getsymbol = revsetlang.getsymbol
+getstring = revsetlang.getstring
+getinteger = revsetlang.getinteger
+getlist = revsetlang.getlist
+getrange = revsetlang.getrange
+getargs = revsetlang.getargs
+getargsdict = revsetlang.getargsdict
+
+# constants used as an argument of match() and matchany()
+anyorder = revsetlang.anyorder
+defineorder = revsetlang.defineorder
+followorder = revsetlang.followorder
+
 baseset = smartset.baseset
 generatorset = smartset.generatorset
 spanset = smartset.spanset
@@ -152,213 +164,8 @@ def reachableroots(repo, roots, heads, i
     revs.sort()
     return revs
 
-elements = {
-    # token-type: binding-strength, primary, prefix, infix, suffix
-    "(": (21, None, ("group", 1, ")"), ("func", 1, ")"), None),
-    "##": (20, None, None, ("_concat", 20), None),
-    "~": (18, None, None, ("ancestor", 18), None),
-    "^": (18, None, None, ("parent", 18), "parentpost"),
-    "-": (5, None, ("negate", 19), ("minus", 5), None),
-    "::": (17, None, ("dagrangepre", 17), ("dagrange", 17), "dagrangepost"),
-    "..": (17, None, ("dagrangepre", 17), ("dagrange", 17), "dagrangepost"),
-    ":": (15, "rangeall", ("rangepre", 15), ("range", 15), "rangepost"),
-    "not": (10, None, ("not", 10), None, None),
-    "!": (10, None, ("not", 10), None, None),
-    "and": (5, None, None, ("and", 5), None),
-    "&": (5, None, None, ("and", 5), None),
-    "%": (5, None, None, ("only", 5), "onlypost"),
-    "or": (4, None, None, ("or", 4), None),
-    "|": (4, None, None, ("or", 4), None),
-    "+": (4, None, None, ("or", 4), None),
-    "=": (3, None, None, ("keyvalue", 3), None),
-    ",": (2, None, None, ("list", 2), None),
-    ")": (0, None, None, None, None),
-    "symbol": (0, "symbol", None, None, None),
-    "string": (0, "string", None, None, None),
-    "end": (0, None, None, None, None),
-}
-
-keywords = set(['and', 'or', 'not'])
-
-# default set of valid characters for the initial letter of symbols
-_syminitletters = set(
-    string.ascii_letters +
-    string.digits + pycompat.sysstr('._@')) | set(map(chr, xrange(128, 256)))
-
-# default set of valid characters for non-initial letters of symbols
-_symletters = _syminitletters | set(pycompat.sysstr('-/'))
-
-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
-
-    if program and lookup:
-        # attempt to parse old-style ranges first to deal with
-        # things like old-tag which contain query metacharacters
-        parts = program.split(':', 1)
-        if all(lookup(sym) for sym in parts if sym):
-            if parts[0]:
-                yield ('symbol', parts[0], 0)
-            if len(parts) > 1:
-                s = len(parts[0])
-                yield (':', None, s)
-                if parts[1]:
-                    yield ('symbol', parts[1], s + 1)
-            yield ('end', None, len(program))
-            return
-
-    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 = parser.unescapestr
-            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)
-
 # helpers
 
-_notset = object()
-
-def getsymbol(x):
-    if x and x[0] == 'symbol':
-        return x[1]
-    raise error.ParseError(_('not a symbol'))
-
-def getstring(x, err):
-    if x and (x[0] == 'string' or x[0] == 'symbol'):
-        return x[1]
-    raise error.ParseError(err)
-
-def getinteger(x, err, default=_notset):
-    if not x and default is not _notset:
-        return default
-    try:
-        return int(getstring(x, err))
-    except ValueError:
-        raise error.ParseError(err)
-
-def getlist(x):
-    if not x:
-        return []
-    if x[0] == 'list':
-        return list(x[1:])
-    return [x]
-
-def getrange(x, err):
-    if not x:
-        raise error.ParseError(err)
-    op = x[0]
-    if op == 'range':
-        return x[1], x[2]
-    elif op == 'rangepre':
-        return None, x[1]
-    elif op == 'rangepost':
-        return x[1], None
-    elif op == 'rangeall':
-        return None, None
-    raise error.ParseError(err)
-
-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 getargsdict(x, funcname, keys):
-    return parser.buildargsdict(getlist(x), funcname, parser.splitargspec(keys),
-                                keyvaluenode='keyvalue', keynode='symbol')
-
 def getset(repo, subset, x):
     if not x:
         raise error.ParseError(_("missing argument"))
@@ -2412,350 +2219,6 @@ methods = {
     "parentpost": parentpost,
 }
 
-# Constants for ordering requirement, used in _analyze():
-#
-# If 'define', any nested functions and operations can change the ordering of
-# the entries in the set. If 'follow', any nested functions and operations
-# should take the ordering specified by the first operand to the '&' operator.
-#
-# For instance,
-#
-#   X & (Y | Z)
-#   ^   ^^^^^^^
-#   |   follow
-#   define
-#
-# will be evaluated as 'or(y(x()), z(x()))', where 'x()' can change the order
-# of the entries in the set, but 'y()', 'z()' and 'or()' shouldn't.
-#
-# 'any' means the order doesn't matter. For instance,
-#
-#   X & !Y
-#        ^
-#        any
-#
-# 'y()' can either enforce its ordering requirement or take the ordering
-# specified by 'x()' because 'not()' doesn't care the order.
-#
-# Transition of ordering requirement:
-#
-# 1. starts with 'define'
-# 2. shifts to 'follow' by 'x & y'
-# 3. changes back to 'define' on function call 'f(x)' or function-like
-#    operation 'x (f) y' because 'f' may have its own ordering requirement
-#    for 'x' and 'y' (e.g. 'first(x)')
-#
-anyorder = 'any'        # don't care the order
-defineorder = 'define'  # should define the order
-followorder = 'follow'  # must follow the current order
-
-# transition table for 'x & y', from the current expression 'x' to 'y'
-_tofolloworder = {
-    anyorder: anyorder,
-    defineorder: followorder,
-    followorder: followorder,
-}
-
-def _matchonly(revs, bases):
-    """
-    >>> f = lambda *args: _matchonly(*map(parse, args))
-    >>> f('ancestors(A)', 'not ancestors(B)')
-    ('list', ('symbol', 'A'), ('symbol', 'B'))
-    """
-    if (revs is not None
-        and revs[0] == 'func'
-        and getsymbol(revs[1]) == 'ancestors'
-        and bases is not None
-        and bases[0] == 'not'
-        and bases[1][0] == 'func'
-        and getsymbol(bases[1][1]) == 'ancestors'):
-        return ('list', revs[2], bases[1][2])
-
-def _fixops(x):
-    """Rewrite raw parsed tree to resolve ambiguous syntax which cannot be
-    handled well by our simple top-down parser"""
-    if not isinstance(x, tuple):
-        return x
-
-    op = x[0]
-    if op == 'parent':
-        # x^:y means (x^) : y, not x ^ (:y)
-        # x^:  means (x^) :,   not x ^ (:)
-        post = ('parentpost', x[1])
-        if x[2][0] == 'dagrangepre':
-            return _fixops(('dagrange', post, x[2][1]))
-        elif x[2][0] == 'rangepre':
-            return _fixops(('range', post, x[2][1]))
-        elif x[2][0] == 'rangeall':
-            return _fixops(('rangepost', post))
-    elif op == 'or':
-        # make number of arguments deterministic:
-        # x + y + z -> (or x y z) -> (or (list x y z))
-        return (op, _fixops(('list',) + x[1:]))
-
-    return (op,) + tuple(_fixops(y) for y in x[1:])
-
-def _analyze(x, order):
-    if x is None:
-        return x
-
-    op = x[0]
-    if op == 'minus':
-        return _analyze(('and', x[1], ('not', x[2])), order)
-    elif op == 'only':
-        t = ('func', ('symbol', 'only'), ('list', x[1], x[2]))
-        return _analyze(t, order)
-    elif op == 'onlypost':
-        return _analyze(('func', ('symbol', 'only'), x[1]), order)
-    elif op == 'dagrangepre':
-        return _analyze(('func', ('symbol', 'ancestors'), x[1]), order)
-    elif op == 'dagrangepost':
-        return _analyze(('func', ('symbol', 'descendants'), x[1]), order)
-    elif op == 'negate':
-        s = getstring(x[1], _("can't negate that"))
-        return _analyze(('string', '-' + s), order)
-    elif op in ('string', 'symbol'):
-        return x
-    elif op == 'and':
-        ta = _analyze(x[1], order)
-        tb = _analyze(x[2], _tofolloworder[order])
-        return (op, ta, tb, order)
-    elif op == 'or':
-        return (op, _analyze(x[1], order), order)
-    elif op == 'not':
-        return (op, _analyze(x[1], anyorder), order)
-    elif op == 'rangeall':
-        return (op, None, order)
-    elif op in ('rangepre', 'rangepost', 'parentpost'):
-        return (op, _analyze(x[1], defineorder), order)
-    elif op == 'group':
-        return _analyze(x[1], order)
-    elif op in ('dagrange', 'range', 'parent', 'ancestor'):
-        ta = _analyze(x[1], defineorder)
-        tb = _analyze(x[2], defineorder)
-        return (op, ta, tb, order)
-    elif op == 'list':
-        return (op,) + tuple(_analyze(y, order) for y in x[1:])
-    elif op == 'keyvalue':
-        return (op, x[1], _analyze(x[2], order))
-    elif op == 'func':
-        f = getsymbol(x[1])
-        d = defineorder
-        if f == 'present':
-            # 'present(set)' is known to return the argument set with no
-            # modification, so forward the current order to its argument
-            d = order
-        return (op, x[1], _analyze(x[2], d), order)
-    raise ValueError('invalid operator %r' % op)
-
-def analyze(x, order=defineorder):
-    """Transform raw parsed tree to evaluatable tree which can be fed to
-    optimize() or getset()
-
-    All pseudo operations should be mapped to real operations or functions
-    defined in methods or symbols table respectively.
-
-    'order' specifies how the current expression 'x' is ordered (see the
-    constants defined above.)
-    """
-    return _analyze(x, order)
-
-def _optimize(x, small):
-    if x is None:
-        return 0, x
-
-    smallbonus = 1
-    if small:
-        smallbonus = .5
-
-    op = x[0]
-    if op in ('string', 'symbol'):
-        return smallbonus, x # single revisions are small
-    elif op == 'and':
-        wa, ta = _optimize(x[1], True)
-        wb, tb = _optimize(x[2], True)
-        order = x[3]
-        w = min(wa, wb)
-
-        # (::x and not ::y)/(not ::y and ::x) have a fast path
-        tm = _matchonly(ta, tb) or _matchonly(tb, ta)
-        if tm:
-            return w, ('func', ('symbol', 'only'), tm, order)
-
-        if tb is not None and tb[0] == 'not':
-            return wa, ('difference', ta, tb[1], order)
-
-        if wa > wb:
-            return w, (op, tb, ta, order)
-        return w, (op, ta, tb, order)
-    elif op == 'or':
-        # fast path for machine-generated expression, that is likely to have
-        # lots of trivial revisions: 'a + b + c()' to '_list(a b) + c()'
-        order = x[2]
-        ws, ts, ss = [], [], []
-        def flushss():
-            if not ss:
-                return
-            if len(ss) == 1:
-                w, t = ss[0]
-            else:
-                s = '\0'.join(t[1] for w, t in ss)
-                y = ('func', ('symbol', '_list'), ('string', s), order)
-                w, t = _optimize(y, False)
-            ws.append(w)
-            ts.append(t)
-            del ss[:]
-        for y in getlist(x[1]):
-            w, t = _optimize(y, False)
-            if t is not None and (t[0] == 'string' or t[0] == 'symbol'):
-                ss.append((w, t))
-                continue
-            flushss()
-            ws.append(w)
-            ts.append(t)
-        flushss()
-        if len(ts) == 1:
-            return ws[0], ts[0] # 'or' operation is fully optimized out
-        # we can't reorder trees by weight because it would change the order.
-        # ("sort(a + b)" == "sort(b + a)", but "a + b" != "b + a")
-        #   ts = tuple(t for w, t in sorted(zip(ws, ts), key=lambda wt: wt[0]))
-        return max(ws), (op, ('list',) + tuple(ts), order)
-    elif op == 'not':
-        # Optimize not public() to _notpublic() because we have a fast version
-        if x[1][:3] == ('func', ('symbol', 'public'), None):
-            order = x[1][3]
-            newsym = ('func', ('symbol', '_notpublic'), None, order)
-            o = _optimize(newsym, not small)
-            return o[0], o[1]
-        else:
-            o = _optimize(x[1], not small)
-            order = x[2]
-            return o[0], (op, o[1], order)
-    elif op == 'rangeall':
-        return smallbonus, x
-    elif op in ('rangepre', 'rangepost', 'parentpost'):
-        o = _optimize(x[1], small)
-        order = x[2]
-        return o[0], (op, o[1], order)
-    elif op in ('dagrange', 'range', 'parent', 'ancestor'):
-        wa, ta = _optimize(x[1], small)
-        wb, tb = _optimize(x[2], small)
-        order = x[3]
-        return wa + wb, (op, ta, tb, order)
-    elif op == 'list':
-        ws, ts = zip(*(_optimize(y, small) for y in x[1:]))
-        return sum(ws), (op,) + ts
-    elif op == 'keyvalue':
-        w, t = _optimize(x[2], small)
-        return w, (op, x[1], t)
-    elif op == 'func':
-        f = getsymbol(x[1])
-        wa, ta = _optimize(x[2], small)
-        if f in ('author', 'branch', 'closed', 'date', 'desc', 'file', 'grep',
-                 'keyword', 'outgoing', 'user', 'destination'):
-            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', 'wdir', '_intlist'):
-            w = 0
-        elif f == "sort":
-            w = 10 # assume most sorts look at changelog
-        else:
-            w = 1
-        order = x[3]
-        return w + wa, (op, x[1], ta, order)
-    raise ValueError('invalid operator %r' % op)
-
-def optimize(tree):
-    """Optimize evaluatable tree
-
-    All pseudo operations should be transformed beforehand.
-    """
-    _weight, newtree = _optimize(tree, small=True)
-    return newtree
-
-# the set of valid characters for the initial letter of symbols in
-# alias declarations and definitions
-_aliassyminitletters = _syminitletters | set(pycompat.sysstr('$'))
-
-def _parsewith(spec, lookup=None, syminitletters=None):
-    """Generate a parse tree of given spec with given tokenizing options
-
-    >>> _parsewith('foo($1)', syminitletters=_aliassyminitletters)
-    ('func', ('symbol', 'foo'), ('symbol', '$1'))
-    >>> _parsewith('$1')
-    Traceback (most recent call last):
-      ...
-    ParseError: ("syntax error in revset '$1'", 0)
-    >>> _parsewith('foo bar')
-    Traceback (most recent call last):
-      ...
-    ParseError: ('invalid token', 4)
-    """
-    p = parser.parser(elements)
-    tree, pos = p.parse(tokenize(spec, lookup=lookup,
-                                 syminitletters=syminitletters))
-    if pos != len(spec):
-        raise error.ParseError(_('invalid token'), pos)
-    return _fixops(parser.simplifyinfixops(tree, ('list', 'or')))
-
-class _aliasrules(parser.basealiasrules):
-    """Parsing and expansion rule set of revset aliases"""
-    _section = _('revset alias')
-
-    @staticmethod
-    def _parse(spec):
-        """Parse alias declaration/definition ``spec``
-
-        This allows symbol names to use also ``$`` as an initial letter
-        (for backward compatibility), and callers of this function should
-        examine whether ``$`` is used also for unexpected symbols or not.
-        """
-        return _parsewith(spec, syminitletters=_aliassyminitletters)
-
-    @staticmethod
-    def _trygetfunc(tree):
-        if tree[0] == 'func' and tree[1][0] == 'symbol':
-            return tree[1][1], getlist(tree[2])
-
-def expandaliases(ui, tree):
-    aliases = _aliasrules.buildmap(ui.configitems('revsetalias'))
-    tree = _aliasrules.expand(aliases, tree)
-    # warn about problematic (but not referred) aliases
-    for name, alias in sorted(aliases.iteritems()):
-        if alias.error and not alias.warned:
-            ui.warn(_('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):
-    return _parsewith(spec, lookup=lookup)
-
 def posttreebuilthook(tree, repo):
     # hook for extensions to execute code on the optimized tree
     pass
@@ -2785,15 +2248,16 @@ def matchany(ui, specs, repo=None, order
     if repo:
         lookup = repo.__contains__
     if len(specs) == 1:
-        tree = parse(specs[0], lookup)
+        tree = revsetlang.parse(specs[0], lookup)
     else:
-        tree = ('or', ('list',) + tuple(parse(s, lookup) for s in specs))
+        tree = ('or',
+                ('list',) + tuple(revsetlang.parse(s, lookup) for s in specs))
 
     if ui:
-        tree = expandaliases(ui, tree)
-    tree = foldconcat(tree)
-    tree = analyze(tree, order)
-    tree = optimize(tree)
+        tree = revsetlang.expandaliases(ui, tree)
+    tree = revsetlang.foldconcat(tree)
+    tree = revsetlang.analyze(tree, order)
+    tree = revsetlang.optimize(tree)
     posttreebuilthook(tree, repo)
     return makematcher(tree)
 
@@ -2809,121 +2273,6 @@ def makematcher(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 error.Abort(_('unexpected revspec format character %s')
-                                  % d)
-        else:
-            ret += c
-        pos += 1
-
-    return ret
-
-def prettyformat(tree):
-    return parser.prettyformat(tree, ('string', 'symbol'))
-
-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
-
 def loadpredicate(ui, extname, registrarobj):
     """Load revset predicates from specified registrarobj
     """
diff --git a/mercurial/revset.py b/mercurial/revsetlang.py
copy from mercurial/revset.py
copy to mercurial/revsetlang.py
--- a/mercurial/revset.py
+++ b/mercurial/revsetlang.py
@@ -1,4 +1,4 @@
-# revset.py - revision set queries for mercurial
+# revsetlang.py - parser, tokenizer and utility for revision set language
 #
 # Copyright 2010 Matt Mackall <mpm at selenic.com>
 #
@@ -7,151 +7,16 @@
 
 from __future__ import absolute_import
 
-import heapq
-import re
 import string
 
 from .i18n import _
 from . import (
-    destutil,
-    encoding,
     error,
-    hbisect,
-    match as matchmod,
     node,
-    obsolete as obsmod,
     parser,
-    pathutil,
-    phases,
     pycompat,
-    registrar,
-    repoview,
-    smartset,
-    util,
 )
 
-baseset = smartset.baseset
-generatorset = smartset.generatorset
-spanset = smartset.spanset
-fullreposet = smartset.fullreposet
-
-def _revancestors(repo, revs, followfirst):
-    """Like revlog.ancestors(), but supports followfirst."""
-    if followfirst:
-        cut = 1
-    else:
-        cut = None
-    cl = repo.changelog
-
-    def iterate():
-        revs.sort(reverse=True)
-        irevs = iter(revs)
-        h = []
-
-        inputrev = next(irevs, None)
-        if inputrev is not None:
-            heapq.heappush(h, -inputrev)
-
-        seen = set()
-        while h:
-            current = -heapq.heappop(h)
-            if current == inputrev:
-                inputrev = next(irevs, None)
-                if inputrev is not None:
-                    heapq.heappush(h, -inputrev)
-            if current not in seen:
-                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
-        # XXX this should be 'parentset.min()' assuming 'parentset' is a
-        # smartset (and if it is not, it should.)
-        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 _reachablerootspure(repo, minroot, roots, heads, includepath):
-    """return (heads(::<roots> and ::<heads>))
-
-    If includepath is True, return (<roots>::<heads>)."""
-    if not roots:
-        return []
-    parentrevs = repo.changelog.parentrevs
-    roots = set(roots)
-    visit = list(heads)
-    reachable = set()
-    seen = {}
-    # prefetch all the things! (because python is slow)
-    reached = reachable.add
-    dovisit = visit.append
-    nextvisit = visit.pop
-    # open-code the post-order traversal due to the tiny size of
-    # sys.getrecursionlimit()
-    while visit:
-        rev = nextvisit()
-        if rev in roots:
-            reached(rev)
-            if not includepath:
-                continue
-        parents = parentrevs(rev)
-        seen[rev] = parents
-        for parent in parents:
-            if parent >= minroot and parent not in seen:
-                dovisit(parent)
-    if not reachable:
-        return baseset()
-    if not includepath:
-        return reachable
-    for rev in sorted(seen):
-        for parent in seen[rev]:
-            if parent in reachable:
-                reached(rev)
-    return reachable
-
-def reachableroots(repo, roots, heads, includepath=False):
-    """return (heads(::<roots> and ::<heads>))
-
-    If includepath is True, return (<roots>::<heads>)."""
-    if not roots:
-        return baseset()
-    minroot = roots.min()
-    roots = list(roots)
-    heads = list(heads)
-    try:
-        revs = repo.changelog.reachableroots(minroot, heads, roots, includepath)
-    except AttributeError:
-        revs = _reachablerootspure(repo, minroot, roots, heads, includepath)
-    revs = baseset(revs)
-    revs.sort()
-    return revs
-
 elements = {
     # token-type: binding-strength, primary, prefix, infix, suffix
     "(": (21, None, ("group", 1, ")"), ("func", 1, ")"), None),
@@ -359,2059 +224,6 @@ def getargsdict(x, funcname, keys):
     return parser.buildargsdict(getlist(x), funcname, parser.splitargspec(keys),
                                 keyvaluenode='keyvalue', keynode='symbol')
 
-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
-    # else case should not happen, because all non-func are internal,
-    # ignoring for now.
-    if x[0] == 'func' and x[1][0] == 'symbol' and x[1][1] in symbols:
-        repo.ui.deprecwarn('revset "%s" uses list instead of smartset'
-                           % x[1][1],
-                           '3.9')
-    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 rangeset(repo, subset, x, y, order):
-    m = getset(repo, fullreposet(repo), x)
-    n = getset(repo, fullreposet(repo), y)
-
-    if not m or not n:
-        return baseset()
-    return _makerangeset(repo, subset, m.first(), n.last(), order)
-
-def rangeall(repo, subset, x, order):
-    assert x is None
-    return _makerangeset(repo, subset, 0, len(repo) - 1, order)
-
-def rangepre(repo, subset, y, order):
-    # ':y' can't be rewritten to '0:y' since '0' may be hidden
-    n = getset(repo, fullreposet(repo), y)
-    if not n:
-        return baseset()
-    return _makerangeset(repo, subset, 0, n.last(), order)
-
-def rangepost(repo, subset, x, order):
-    m = getset(repo, fullreposet(repo), x)
-    if not m:
-        return baseset()
-    return _makerangeset(repo, subset, m.first(), len(repo) - 1, order)
-
-def _makerangeset(repo, subset, m, n, order):
-    if m == n:
-        r = baseset([m])
-    elif n == node.wdirrev:
-        r = spanset(repo, m, len(repo)) + baseset([n])
-    elif m == node.wdirrev:
-        r = baseset([m]) + spanset(repo, len(repo) - 1, n - 1)
-    elif m < n:
-        r = spanset(repo, m, n + 1)
-    else:
-        r = spanset(repo, m, n - 1)
-
-    if order == defineorder:
-        return r & subset
-    else:
-        # carrying the sorting over when possible would be more efficient
-        return subset & r
-
-def dagrange(repo, subset, x, y, order):
-    r = fullreposet(repo)
-    xs = reachableroots(repo, getset(repo, r, x), getset(repo, r, y),
-                         includepath=True)
-    return subset & xs
-
-def andset(repo, subset, x, y, order):
-    return getset(repo, getset(repo, subset, x), y)
-
-def differenceset(repo, subset, x, y, order):
-    return getset(repo, subset, x) - getset(repo, subset, y)
-
-def _orsetlist(repo, subset, xs):
-    assert xs
-    if len(xs) == 1:
-        return getset(repo, subset, xs[0])
-    p = len(xs) // 2
-    a = _orsetlist(repo, subset, xs[:p])
-    b = _orsetlist(repo, subset, xs[p:])
-    return a + b
-
-def orset(repo, subset, x, order):
-    xs = getlist(x)
-    if order == followorder:
-        # slow path to take the subset order
-        return subset & _orsetlist(repo, fullreposet(repo), xs)
-    else:
-        return _orsetlist(repo, subset, xs)
-
-def notset(repo, subset, x, order):
-    return subset - getset(repo, subset, x)
-
-def listset(repo, subset, *xs):
-    raise error.ParseError(_("can't use a list in this context"),
-                           hint=_('see hg help "revsets.x or y"'))
-
-def keyvaluepair(repo, subset, k, v):
-    raise error.ParseError(_("can't use a key-value pair in this context"))
-
-def func(repo, subset, a, b, order):
-    f = getsymbol(a)
-    if f in symbols:
-        func = symbols[f]
-        if getattr(func, '_takeorder', False):
-            return func(repo, subset, b, order)
-        return func(repo, subset, b)
-
-    keep = lambda fn: getattr(fn, '__doc__', None) is not None
-
-    syms = [s for (s, fn) in symbols.items() if keep(fn)]
-    raise error.UnknownIdentifier(f, syms)
-
-# functions
-
-# symbols are callables like:
-#   fn(repo, subset, x)
-# with:
-#   repo - current repository instance
-#   subset - of revisions to be examined
-#   x - argument in tree form
-symbols = {}
-
-# 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()
-
-predicate = registrar.revsetpredicate()
-
- at predicate('_destupdate')
-def _destupdate(repo, subset, x):
-    # experimental revset for update destination
-    args = getargsdict(x, 'limit', 'clean')
-    return subset & baseset([destutil.destupdate(repo, **args)[0]])
-
- at predicate('_destmerge')
-def _destmerge(repo, subset, x):
-    # experimental revset for merge destination
-    sourceset = None
-    if x is not None:
-        sourceset = getset(repo, fullreposet(repo), x)
-    return subset & baseset([destutil.destmerge(repo, sourceset=sourceset)])
-
- at predicate('adds(pattern)', safe=True)
-def adds(repo, subset, x):
-    """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)
-
- at predicate('ancestor(*changeset)', safe=True)
-def ancestor(repo, subset, x):
-    """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
-
- at predicate('ancestors(set)', safe=True)
-def ancestors(repo, subset, x):
-    """Changesets that are ancestors of a changeset in set.
-    """
-    return _ancestors(repo, subset, x)
-
- at predicate('_firstancestors', safe=True)
-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, order):
-    """``set~n``
-    Changesets that are the Nth ancestor (first parents only) of a changeset
-    in set.
-    """
-    n = getinteger(n, _("~ 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
-
- at predicate('author(string)', safe=True)
-def author(repo, subset, x):
-    """Alias for ``user(string)``.
-    """
-    # i18n: "author" is a keyword
-    n = getstring(x, _("author requires a string"))
-    kind, pattern, matcher = _substringmatcher(n, casesensitive=False)
-    return subset.filter(lambda x: matcher(repo[x].user()),
-                         condrepr=('<user %r>', n))
-
- at predicate('bisect(string)', safe=True)
-def bisect(repo, subset, x):
-    """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
- at predicate('bisected', safe=True)
-def bisected(repo, subset, x):
-    return bisect(repo, subset, x)
-
- at predicate('bookmark([name])', safe=True)
-def bookmark(repo, subset, x):
-    """The named bookmark or all bookmarks.
-
-    Pattern matching is supported for `name`. See :hg:`help revisions.patterns`.
-    """
-    # 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 = util.stringmatcher(bm)
-        bms = set()
-        if kind == 'literal':
-            bmrev = repo._bookmarks.get(pattern, None)
-            if not bmrev:
-                raise error.RepoLookupError(_("bookmark '%s' does not exist")
-                                            % pattern)
-            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
-
- at predicate('branch(string or set)', safe=True)
-def branch(repo, subset, x):
-    """
-    All changesets belonging to the given branch or the branches of the given
-    changesets.
-
-    Pattern matching is supported for `string`. See
-    :hg:`help revisions.patterns`.
-    """
-    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 = util.stringmatcher(b)
-        if kind == 'literal':
-            # note: falls through to the revspec case if no branch with
-            # this name exists and pattern kind is not specified explicitly
-            if pattern in repo.branchmap():
-                return subset.filter(lambda r: matcher(getbi(r)[0]),
-                                     condrepr=('<branch %r>', b))
-            if b.startswith('literal:'):
-                raise error.RepoLookupError(_("branch '%s' does not exist")
-                                            % pattern)
-        else:
-            return subset.filter(lambda r: matcher(getbi(r)[0]),
-                                 condrepr=('<branch %r>', b))
-
-    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,
-                         condrepr=lambda: '<branch %r>' % sorted(b))
-
- at predicate('bumped()', safe=True)
-def bumped(repo, subset, x):
-    """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
-
- at predicate('bundle()', safe=True)
-def bundle(repo, subset, x):
-    """Changesets in the bundle.
-
-    Bundle must be specified by the -R option."""
-
-    try:
-        bundlerevs = repo.changelog.bundlerevs
-    except AttributeError:
-        raise error.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, condrepr=('<status[%r] %r>', field, pat))
-
-def _children(repo, subset, parentset):
-    if not parentset:
-        return baseset()
-    cs = set()
-    pr = repo.changelog.parentrevs
-    minrev = parentset.min()
-    nullrev = node.nullrev
-    for r in subset:
-        if r <= minrev:
-            continue
-        p1, p2 = pr(r)
-        if p1 in parentset:
-            cs.add(r)
-        if p2 != nullrev and p2 in parentset:
-            cs.add(r)
-    return baseset(cs)
-
- at predicate('children(set)', safe=True)
-def children(repo, subset, x):
-    """Child changesets of changesets in set.
-    """
-    s = getset(repo, fullreposet(repo), x)
-    cs = _children(repo, subset, s)
-    return subset & cs
-
- at predicate('closed()', safe=True)
-def closed(repo, subset, x):
-    """Changeset is closed.
-    """
-    # i18n: "closed" is a keyword
-    getargs(x, 0, 0, _("closed takes no arguments"))
-    return subset.filter(lambda r: repo[r].closesbranch(),
-                         condrepr='<branch closed>')
-
- at predicate('contains(pattern)')
-def contains(repo, subset, x):
-    """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, condrepr=('<contains %r>', pat))
-
- at predicate('converted([id])', safe=True)
-def converted(repo, subset, x):
-    """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),
-                         condrepr=('<converted %r>', rev))
-
- at predicate('date(interval)', safe=True)
-def date(repo, subset, x):
-    """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]),
-                         condrepr=('<date %r>', ds))
-
- at predicate('desc(string)', safe=True)
-def desc(repo, subset, x):
-    """Search commit message for string. The match is case-insensitive.
-
-    Pattern matching is supported for `string`. See
-    :hg:`help revisions.patterns`.
-    """
-    # i18n: "desc" is a keyword
-    ds = getstring(x, _("desc requires a string"))
-
-    kind, pattern, matcher = _substringmatcher(ds, casesensitive=False)
-
-    return subset.filter(lambda r: matcher(repo[r].description()),
-                         condrepr=('<desc %r>', ds))
-
-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
-
- at predicate('descendants(set)', safe=True)
-def descendants(repo, subset, x):
-    """Changesets which are descendants of changesets in set.
-    """
-    return _descendants(repo, subset, x)
-
- at predicate('_firstdescendants', safe=True)
-def _firstdescendants(repo, subset, x):
-    # ``_firstdescendants(set)``
-    # Like ``descendants(set)`` but follows only the first parents.
-    return _descendants(repo, subset, x, followfirst=True)
-
- at predicate('destination([set])', safe=True)
-def destination(repo, subset, x):
-    """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__,
-                         condrepr=lambda: '<destination %r>' % sorted(dests))
-
- at predicate('divergent()', safe=True)
-def divergent(repo, subset, x):
-    """
-    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
-
- at predicate('extinct()', safe=True)
-def extinct(repo, subset, x):
-    """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
-
- at predicate('extra(label, [value])', safe=True)
-def extra(repo, subset, x):
-    """Changesets with the given label in the extra metadata, with the given
-    optional value.
-
-    Pattern matching is supported for `value`. See
-    :hg:`help revisions.patterns`.
-    """
-    args = getargsdict(x, 'extra', 'label value')
-    if 'label' not in args:
-        # i18n: "extra" is a keyword
-        raise error.ParseError(_('extra takes at least 1 argument'))
-    # i18n: "extra" is a keyword
-    label = getstring(args['label'], _('first argument to extra must be '
-                                       'a string'))
-    value = None
-
-    if 'value' in args:
-        # i18n: "extra" is a keyword
-        value = getstring(args['value'], _('second argument to extra must be '
-                                           'a string'))
-        kind, value, matcher = util.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),
-                         condrepr=('<extra[%r] %r>', label, value))
-
- at predicate('filelog(pattern)', safe=True)
-def filelog(repo, subset, x):
-    """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:
-        fl = repo.file(f)
-        known = {}
-        scanpos = 0
-        for fr in list(fl):
-            fn = fl.node(fr)
-            if fn in known:
-                s.add(known[fn])
-                continue
-
-            lr = fl.linkrev(fr)
-            if lr in cl:
-                s.add(lr)
-            elif scanpos is not None:
-                # lowest matching changeset is filtered, scan further
-                # ahead in changelog
-                start = max(lr, scanpos) + 1
-                scanpos = None
-                for r in cl.revs(start):
-                    # minimize parsing of non-matching entries
-                    if f in cl.revision(r) and f in cl.readfiles(r):
-                        try:
-                            # try to use manifest delta fastpath
-                            n = repo[r].filenode(f)
-                            if n not in known:
-                                if n == fn:
-                                    s.add(r)
-                                    scanpos = r
-                                    break
-                                else:
-                                    known[n] = r
-                        except error.ManifestLookupError:
-                            # deletion in changelog
-                            continue
-
-    return subset & s
-
- at predicate('first(set, [n])', safe=True)
-def first(repo, subset, x):
-    """An alias for limit().
-    """
-    return limit(repo, subset, x)
-
-def _follow(repo, subset, x, name, followfirst=False):
-    l = getargs(x, 0, 2, _("%s takes no arguments or a pattern "
-                           "and an optional revset") % name)
-    c = repo['.']
-    if l:
-        x = getstring(l[0], _("%s expected a pattern") % name)
-        rev = None
-        if len(l) >= 2:
-            revs = getset(repo, fullreposet(repo), l[1])
-            if len(revs) != 1:
-                raise error.RepoLookupError(
-                        _("%s expected one starting revision") % name)
-            rev = revs.last()
-            c = repo[rev]
-        matcher = matchmod.match(repo.root, repo.getcwd(), [x],
-                                 ctx=repo[rev], default='path')
-
-        files = c.manifest().walk(matcher)
-
-        s = set()
-        for fname in files:
-            fctx = c[fname]
-            s = s.union(set(c.rev() for c in fctx.ancestors(followfirst)))
-            # include the revision responsible for the most recent version
-            s.add(fctx.introrev())
-    else:
-        s = _revancestors(repo, baseset([c.rev()]), followfirst)
-
-    return subset & s
-
- at predicate('follow([pattern[, startrev]])', safe=True)
-def follow(repo, subset, x):
-    """
-    An alias for ``::.`` (ancestors of the working directory's first parent).
-    If pattern is specified, the histories of files matching given
-    pattern in the revision given by startrev are followed, including copies.
-    """
-    return _follow(repo, subset, x, 'follow')
-
- at predicate('_followfirst', safe=True)
-def _followfirst(repo, subset, x):
-    # ``followfirst([pattern[, startrev]])``
-    # Like ``follow([pattern[, startrev]])`` but follows only the first parent
-    # of every revisions or files revisions.
-    return _follow(repo, subset, x, '_followfirst', followfirst=True)
-
- at predicate('followlines(file, fromline:toline[, startrev=.])', safe=True)
-def followlines(repo, subset, x):
-    """Changesets modifying `file` in line range ('fromline', 'toline').
-
-    Line range corresponds to 'file' content at 'startrev' and should hence be
-    consistent with file size. If startrev is not specified, working directory's
-    parent is used.
-    """
-    from . import context  # avoid circular import issues
-
-    args = getargsdict(x, 'followlines', 'file *lines startrev')
-    if len(args['lines']) != 1:
-        raise error.ParseError(_("followlines requires a line range"))
-
-    rev = '.'
-    if 'startrev' in args:
-        revs = getset(repo, fullreposet(repo), args['startrev'])
-        if len(revs) != 1:
-            raise error.ParseError(
-                _("followlines expects exactly one revision"))
-        rev = revs.last()
-
-    pat = getstring(args['file'], _("followlines requires a pattern"))
-    if not matchmod.patkind(pat):
-        fname = pathutil.canonpath(repo.root, repo.getcwd(), pat)
-    else:
-        m = matchmod.match(repo.root, repo.getcwd(), [pat], ctx=repo[rev])
-        files = [f for f in repo[rev] if m(f)]
-        if len(files) != 1:
-            raise error.ParseError(_("followlines expects exactly one file"))
-        fname = files[0]
-
-    lr = getrange(args['lines'][0], _("followlines expects a line range"))
-    fromline, toline = [getinteger(a, _("line range bounds must be integers"))
-                        for a in lr]
-    if toline - fromline < 0:
-        raise error.ParseError(_("line range must be positive"))
-    if fromline < 1:
-        raise error.ParseError(_("fromline must be strictly positive"))
-    fromline -= 1
-
-    fctx = repo[rev].filectx(fname)
-    revs = (c.rev() for c in context.blockancestors(fctx, fromline, toline))
-    return subset & generatorset(revs, iterasc=False)
-
- at predicate('all()', safe=True)
-def getall(repo, subset, x):
-    """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
-
- at predicate('grep(regex)')
-def grep(repo, subset, x):
-    """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 as 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, condrepr=('<grep %r>', gr.pattern))
-
- at predicate('_matchfiles', safe=True)
-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.
-
-    l = getargs(x, 1, -1, "_matchfiles requires at least one argument")
-    pats, inc, exc = [], [], []
-    rev, default = None, None
-    for arg in l:
-        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:
-                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:
-                raise error.ParseError('_matchfiles expected at most one '
-                                       'default mode')
-            default = value
-        else:
-            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)
-
-    # This directly read the changelog data as creating changectx for all
-    # revisions is quite expensive.
-    getfiles = repo.changelog.readfiles
-    wdirrev = node.wdirrev
-    def matches(x):
-        if x == wdirrev:
-            files = repo[x].files()
-        else:
-            files = getfiles(x)
-        for f in files:
-            if m(f):
-                return True
-        return False
-
-    return subset.filter(matches,
-                         condrepr=('<matchfiles patterns=%r, include=%r '
-                                   'exclude=%r, default=%r, rev=%r>',
-                                   pats, inc, exc, default, rev))
-
- at predicate('file(pattern)', safe=True)
-def hasfile(repo, subset, x):
-    """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))
-
- at predicate('head()', safe=True)
-def head(repo, subset, x):
-    """Changeset is a named branch head.
-    """
-    # i18n: "head" is a keyword
-    getargs(x, 0, 0, _("head takes no arguments"))
-    hs = set()
-    cl = repo.changelog
-    for ls in repo.branchmap().itervalues():
-        hs.update(cl.rev(h) for h in ls)
-    return subset & baseset(hs)
-
- at predicate('heads(set)', safe=True)
-def heads(repo, subset, x):
-    """Members of set with no children in set.
-    """
-    s = getset(repo, subset, x)
-    ps = parents(repo, subset, x)
-    return s - ps
-
- at predicate('hidden()', safe=True)
-def hidden(repo, subset, x):
-    """Hidden changesets.
-    """
-    # i18n: "hidden" is a keyword
-    getargs(x, 0, 0, _("hidden takes no arguments"))
-    hiddenrevs = repoview.filterrevs(repo, 'visible')
-    return subset & hiddenrevs
-
- at predicate('keyword(string)', safe=True)
-def keyword(repo, subset, x):
-    """Search commit message, user name, and names of changed files for
-    string. The match is case-insensitive.
-
-    For a regular expression or case sensitive search of these fields, use
-    ``grep(regex)``.
-    """
-    # i18n: "keyword" is a keyword
-    kw = encoding.lower(getstring(x, _("keyword requires a string")))
-
-    def matches(r):
-        c = repo[r]
-        return any(kw in encoding.lower(t)
-                   for t in c.files() + [c.user(), c.description()])
-
-    return subset.filter(matches, condrepr=('<keyword %r>', kw))
-
- at predicate('limit(set[, n[, offset]])', safe=True)
-def limit(repo, subset, x):
-    """First n members of set, defaulting to 1, starting from offset.
-    """
-    args = getargsdict(x, 'limit', 'set n offset')
-    if 'set' not in args:
-        # i18n: "limit" is a keyword
-        raise error.ParseError(_("limit requires one to three arguments"))
-    # i18n: "limit" is a keyword
-    lim = getinteger(args.get('n'), _("limit expects a number"), default=1)
-    # i18n: "limit" is a keyword
-    ofs = getinteger(args.get('offset'), _("limit expects a number"), default=0)
-    if ofs < 0:
-        raise error.ParseError(_("negative offset"))
-    os = getset(repo, fullreposet(repo), args['set'])
-    result = []
-    it = iter(os)
-    for x in xrange(ofs):
-        y = next(it, None)
-        if y is None:
-            break
-    for x in xrange(lim):
-        y = next(it, None)
-        if y is None:
-            break
-        elif y in subset:
-            result.append(y)
-    return baseset(result, datarepr=('<limit n=%d, offset=%d, %r, %r>',
-                                     lim, ofs, subset, os))
-
- at predicate('last(set, [n])', safe=True)
-def last(repo, subset, x):
-    """Last n members of set, defaulting to 1.
-    """
-    # i18n: "last" is a keyword
-    l = getargs(x, 1, 2, _("last requires one or two arguments"))
-    lim = 1
-    if len(l) == 2:
-        # i18n: "last" is a keyword
-        lim = getinteger(l[1], _("last expects a number"))
-    os = getset(repo, fullreposet(repo), l[0])
-    os.reverse()
-    result = []
-    it = iter(os)
-    for x in xrange(lim):
-        y = next(it, None)
-        if y is None:
-            break
-        elif y in subset:
-            result.append(y)
-    return baseset(result, datarepr=('<last n=%d, %r, %r>', lim, subset, os))
-
- at predicate('max(set)', safe=True)
-def maxrev(repo, subset, x):
-    """Changeset with highest revision number in set.
-    """
-    os = getset(repo, fullreposet(repo), x)
-    try:
-        m = os.max()
-        if m in subset:
-            return baseset([m], datarepr=('<max %r, %r>', subset, os))
-    except ValueError:
-        # os.max() throws a ValueError when the collection is empty.
-        # Same as python's max().
-        pass
-    return baseset(datarepr=('<max %r, %r>', subset, os))
-
- at predicate('merge()', safe=True)
-def merge(repo, subset, x):
-    """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,
-                         condrepr='<merge>')
-
- at predicate('branchpoint()', safe=True)
-def branchpoint(repo, subset, x):
-    """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()
-    # XXX this should be 'parentset.min()' assuming 'parentset' is a smartset
-    # (and if it is not, it should.)
-    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,
-                         condrepr='<branchpoint>')
-
- at predicate('min(set)', safe=True)
-def minrev(repo, subset, x):
-    """Changeset with lowest revision number in set.
-    """
-    os = getset(repo, fullreposet(repo), x)
-    try:
-        m = os.min()
-        if m in subset:
-            return baseset([m], datarepr=('<min %r, %r>', subset, os))
-    except ValueError:
-        # os.min() throws a ValueError when the collection is empty.
-        # Same as python's min().
-        pass
-    return baseset(datarepr=('<min %r, %r>', subset, os))
-
- at predicate('modifies(pattern)', safe=True)
-def modifies(repo, subset, x):
-    """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)
-
- at predicate('named(namespace)')
-def named(repo, subset, x):
-    """The changesets in a given namespace.
-
-    Pattern matching is supported for `namespace`. See
-    :hg:`help revisions.patterns`.
-    """
-    # 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 = util.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
-
- at predicate('id(string)', safe=True)
-def node_(repo, subset, x):
-    """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
-
- at predicate('obsolete()', safe=True)
-def obsolete(repo, subset, x):
-    """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
-
- at predicate('only(set, [set])', safe=True)
-def only(repo, subset, x):
-    """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))
-    # XXX we should turn this into a baseset instead of a set, smartset may do
-    # some optimizations from the fact this is a baseset.
-    return subset & results
-
- at predicate('origin([set])', safe=True)
-def origin(repo, subset, x):
-    """
-    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])
-    # XXX we should turn this into a baseset instead of a set, smartset may do
-    # some optimizations from the fact this is a baseset.
-    return subset & o
-
- at predicate('outgoing([path])', safe=False)
-def outgoing(repo, subset, x):
-    """Changesets not found in the specified destination repository, or the
-    default push location.
-    """
-    # Avoid cycles.
-    from . import (
-        discovery,
-        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
-
- at predicate('p1([set])', safe=True)
-def p1(repo, subset, x):
-    """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])
-    # XXX we should turn this into a baseset instead of a set, smartset may do
-    # some optimizations from the fact this is a baseset.
-    return subset & ps
-
- at predicate('p2([set])', safe=True)
-def p2(repo, subset, x):
-    """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])
-    # XXX we should turn this into a baseset instead of a set, smartset may do
-    # some optimizations from the fact this is a baseset.
-    return subset & ps
-
-def parentpost(repo, subset, x, order):
-    return p1(repo, subset, x)
-
- at predicate('parents([set])', safe=True)
-def parents(repo, subset, x):
-    """
-    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
-        up = ps.update
-        parentrevs = cl.parentrevs
-        for r in getset(repo, fullreposet(repo), x):
-            if r == node.wdirrev:
-                up(p.rev() for p in repo[r].parents())
-            else:
-                up(parentrevs(r))
-    ps -= set([node.nullrev])
-    return subset & ps
-
-def _phase(repo, subset, *targets):
-    """helper to select all rev in <targets> phases"""
-    s = repo._phasecache.getrevset(repo, targets)
-    return subset & s
-
- at predicate('draft()', safe=True)
-def draft(repo, subset, x):
-    """Changeset in draft phase."""
-    # i18n: "draft" is a keyword
-    getargs(x, 0, 0, _("draft takes no arguments"))
-    target = phases.draft
-    return _phase(repo, subset, target)
-
- at predicate('secret()', safe=True)
-def secret(repo, subset, x):
-    """Changeset in secret phase."""
-    # i18n: "secret" is a keyword
-    getargs(x, 0, 0, _("secret takes no arguments"))
-    target = phases.secret
-    return _phase(repo, subset, target)
-
-def parentspec(repo, subset, x, n, order):
-    """``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 parents[1] != node.nullrev:
-                ps.add(parents[1])
-    return subset & ps
-
- at predicate('present(set)', safe=True)
-def present(repo, subset, x):
-    """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()
-
-# for internal use
- at predicate('_notpublic', safe=True)
-def _notpublic(repo, subset, x):
-    getargs(x, 0, 0, "_notpublic takes no arguments")
-    return _phase(repo, subset, phases.draft, phases.secret)
-
- at predicate('public()', safe=True)
-def public(repo, subset, x):
-    """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, condrepr=('<phase %r>', target),
-                         cache=False)
-
- at predicate('remote([id [,path]])', safe=False)
-def remote(repo, subset, x):
-    """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.
-    """
-
-    from . import hg # avoid start-up nasties
-    # i18n: "remote" is a keyword
-    l = getargs(x, 0, 2, _("remote takes zero, one, or two 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()
-
- at predicate('removes(pattern)', safe=True)
-def removes(repo, subset, x):
-    """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)
-
- at predicate('rev(number)', safe=True)
-def rev(repo, subset, x):
-    """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])
-
- at predicate('matching(revision [, field])', safe=True)
-def matching(repo, subset, x):
-    """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, condrepr=('<matching%r %r>', fields, revs))
-
- at predicate('reverse(set)', safe=True, takeorder=True)
-def reverse(repo, subset, x, order):
-    """Reverse order of set.
-    """
-    l = getset(repo, subset, x)
-    if order == defineorder:
-        l.reverse()
-    return l
-
- at predicate('roots(set)', safe=True)
-def roots(repo, subset, x):
-    """Changesets in set with no parent changeset in set.
-    """
-    s = getset(repo, fullreposet(repo), x)
-    parents = repo.changelog.parentrevs
-    def filter(r):
-        for p in parents(r):
-            if 0 <= p and p in s:
-                return False
-        return True
-    return subset & s.filter(filter, condrepr='<roots>')
-
-_sortkeyfuncs = {
-    'rev': lambda c: c.rev(),
-    'branch': lambda c: c.branch(),
-    'desc': lambda c: c.description(),
-    'user': lambda c: c.user(),
-    'author': lambda c: c.user(),
-    'date': lambda c: c.date()[0],
-}
-
-def _getsortargs(x):
-    """Parse sort options into (set, [(key, reverse)], opts)"""
-    args = getargsdict(x, 'sort', 'set keys topo.firstbranch')
-    if 'set' not in args:
-        # i18n: "sort" is a keyword
-        raise error.ParseError(_('sort requires one or two arguments'))
-    keys = "rev"
-    if 'keys' in args:
-        # i18n: "sort" is a keyword
-        keys = getstring(args['keys'], _("sort spec must be a string"))
-
-    keyflags = []
-    for k in keys.split():
-        fk = k
-        reverse = (k[0] == '-')
-        if reverse:
-            k = k[1:]
-        if k not in _sortkeyfuncs and k != 'topo':
-            raise error.ParseError(_("unknown sort key %r") % fk)
-        keyflags.append((k, reverse))
-
-    if len(keyflags) > 1 and any(k == 'topo' for k, reverse in keyflags):
-        # i18n: "topo" is a keyword
-        raise error.ParseError(_('topo sort order cannot be combined '
-                                 'with other sort keys'))
-
-    opts = {}
-    if 'topo.firstbranch' in args:
-        if any(k == 'topo' for k, reverse in keyflags):
-            opts['topo.firstbranch'] = args['topo.firstbranch']
-        else:
-            # i18n: "topo" and "topo.firstbranch" are keywords
-            raise error.ParseError(_('topo.firstbranch can only be used '
-                                     'when using the topo sort key'))
-
-    return args['set'], keyflags, opts
-
- at predicate('sort(set[, [-]key... [, ...]])', safe=True, takeorder=True)
-def sort(repo, subset, x, order):
-    """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
-    - ``topo`` for a reverse topographical sort
-
-    The ``topo`` sort order cannot be combined with other sort keys. This sort
-    takes one optional argument, ``topo.firstbranch``, which takes a revset that
-    specifies what topographical branches to prioritize in the sort.
-
-    """
-    s, keyflags, opts = _getsortargs(x)
-    revs = getset(repo, subset, s)
-
-    if not keyflags or order != defineorder:
-        return revs
-    if len(keyflags) == 1 and keyflags[0][0] == "rev":
-        revs.sort(reverse=keyflags[0][1])
-        return revs
-    elif keyflags[0][0] == "topo":
-        firstbranch = ()
-        if 'topo.firstbranch' in opts:
-            firstbranch = getset(repo, subset, opts['topo.firstbranch'])
-        revs = baseset(_toposort(revs, repo.changelog.parentrevs, firstbranch),
-                       istopo=True)
-        if keyflags[0][1]:
-            revs.reverse()
-        return revs
-
-    # sort() is guaranteed to be stable
-    ctxs = [repo[r] for r in revs]
-    for k, reverse in reversed(keyflags):
-        ctxs.sort(key=_sortkeyfuncs[k], reverse=reverse)
-    return baseset([c.rev() for c in ctxs])
-
-def _toposort(revs, parentsfunc, firstbranch=()):
-    """Yield revisions from heads to roots one (topo) branch at a time.
-
-    This function aims to be used by a graph generator that wishes to minimize
-    the number of parallel branches and their interleaving.
-
-    Example iteration order (numbers show the "true" order in a changelog):
-
-      o  4
-      |
-      o  1
-      |
-      | o  3
-      | |
-      | o  2
-      |/
-      o  0
-
-    Note that the ancestors of merges are understood by the current
-    algorithm to be on the same branch. This means no reordering will
-    occur behind a merge.
-    """
-
-    ### Quick summary of the algorithm
-    #
-    # This function is based around a "retention" principle. We keep revisions
-    # in memory until we are ready to emit a whole branch that immediately
-    # "merges" into an existing one. This reduces the number of parallel
-    # branches with interleaved revisions.
-    #
-    # During iteration revs are split into two groups:
-    # A) revision already emitted
-    # B) revision in "retention". They are stored as different subgroups.
-    #
-    # for each REV, we do the following logic:
-    #
-    #   1) if REV is a parent of (A), we will emit it. If there is a
-    #   retention group ((B) above) that is blocked on REV being
-    #   available, we emit all the revisions out of that retention
-    #   group first.
-    #
-    #   2) else, we'll search for a subgroup in (B) awaiting for REV to be
-    #   available, if such subgroup exist, we add REV to it and the subgroup is
-    #   now awaiting for REV.parents() to be available.
-    #
-    #   3) finally if no such group existed in (B), we create a new subgroup.
-    #
-    #
-    # To bootstrap the algorithm, we emit the tipmost revision (which
-    # puts it in group (A) from above).
-
-    revs.sort(reverse=True)
-
-    # Set of parents of revision that have been emitted. They can be considered
-    # unblocked as the graph generator is already aware of them so there is no
-    # need to delay the revisions that reference them.
-    #
-    # If someone wants to prioritize a branch over the others, pre-filling this
-    # set will force all other branches to wait until this branch is ready to be
-    # emitted.
-    unblocked = set(firstbranch)
-
-    # list of groups waiting to be displayed, each group is defined by:
-    #
-    #   (revs:    lists of revs waiting to be displayed,
-    #    blocked: set of that cannot be displayed before those in 'revs')
-    #
-    # The second value ('blocked') correspond to parents of any revision in the
-    # group ('revs') that is not itself contained in the group. The main idea
-    # of this algorithm is to delay as much as possible the emission of any
-    # revision.  This means waiting for the moment we are about to display
-    # these parents to display the revs in a group.
-    #
-    # This first implementation is smart until it encounters a merge: it will
-    # emit revs as soon as any parent is about to be emitted and can grow an
-    # arbitrary number of revs in 'blocked'. In practice this mean we properly
-    # retains new branches but gives up on any special ordering for ancestors
-    # of merges. The implementation can be improved to handle this better.
-    #
-    # The first subgroup is special. It corresponds to all the revision that
-    # were already emitted. The 'revs' lists is expected to be empty and the
-    # 'blocked' set contains the parents revisions of already emitted revision.
-    #
-    # You could pre-seed the <parents> set of groups[0] to a specific
-    # changesets to select what the first emitted branch should be.
-    groups = [([], unblocked)]
-    pendingheap = []
-    pendingset = set()
-
-    heapq.heapify(pendingheap)
-    heappop = heapq.heappop
-    heappush = heapq.heappush
-    for currentrev in revs:
-        # Heap works with smallest element, we want highest so we invert
-        if currentrev not in pendingset:
-            heappush(pendingheap, -currentrev)
-            pendingset.add(currentrev)
-        # iterates on pending rev until after the current rev have been
-        # processed.
-        rev = None
-        while rev != currentrev:
-            rev = -heappop(pendingheap)
-            pendingset.remove(rev)
-
-            # Seek for a subgroup blocked, waiting for the current revision.
-            matching = [i for i, g in enumerate(groups) if rev in g[1]]
-
-            if matching:
-                # The main idea is to gather together all sets that are blocked
-                # on the same revision.
-                #
-                # Groups are merged when a common blocking ancestor is
-                # observed. For example, given two groups:
-                #
-                # revs [5, 4] waiting for 1
-                # revs [3, 2] waiting for 1
-                #
-                # These two groups will be merged when we process
-                # 1. In theory, we could have merged the groups when
-                # we added 2 to the group it is now in (we could have
-                # noticed the groups were both blocked on 1 then), but
-                # the way it works now makes the algorithm simpler.
-                #
-                # We also always keep the oldest subgroup first. We can
-                # probably improve the behavior by having the longest set
-                # first. That way, graph algorithms could minimise the length
-                # of parallel lines their drawing. This is currently not done.
-                targetidx = matching.pop(0)
-                trevs, tparents = groups[targetidx]
-                for i in matching:
-                    gr = groups[i]
-                    trevs.extend(gr[0])
-                    tparents |= gr[1]
-                # delete all merged subgroups (except the one we kept)
-                # (starting from the last subgroup for performance and
-                # sanity reasons)
-                for i in reversed(matching):
-                    del groups[i]
-            else:
-                # This is a new head. We create a new subgroup for it.
-                targetidx = len(groups)
-                groups.append(([], set([rev])))
-
-            gr = groups[targetidx]
-
-            # We now add the current nodes to this subgroups. This is done
-            # after the subgroup merging because all elements from a subgroup
-            # that relied on this rev must precede it.
-            #
-            # we also update the <parents> set to include the parents of the
-            # new nodes.
-            if rev == currentrev: # only display stuff in rev
-                gr[0].append(rev)
-            gr[1].remove(rev)
-            parents = [p for p in parentsfunc(rev) if p > node.nullrev]
-            gr[1].update(parents)
-            for p in parents:
-                if p not in pendingset:
-                    pendingset.add(p)
-                    heappush(pendingheap, -p)
-
-            # Look for a subgroup to display
-            #
-            # When unblocked is empty (if clause), we were not waiting for any
-            # revisions during the first iteration (if no priority was given) or
-            # if we emitted a whole disconnected set of the graph (reached a
-            # root).  In that case we arbitrarily take the oldest known
-            # subgroup. The heuristic could probably be better.
-            #
-            # Otherwise (elif clause) if the subgroup is blocked on
-            # a revision we just emitted, we can safely emit it as
-            # well.
-            if not unblocked:
-                if len(groups) > 1:  # display other subset
-                    targetidx = 1
-                    gr = groups[1]
-            elif not gr[1] & unblocked:
-                gr = None
-
-            if gr is not None:
-                # update the set of awaited revisions with the one from the
-                # subgroup
-                unblocked |= gr[1]
-                # output all revisions in the subgroup
-                for r in gr[0]:
-                    yield r
-                # delete the subgroup that you just output
-                # unless it is groups[0] in which case you just empty it.
-                if targetidx:
-                    del groups[targetidx]
-                else:
-                    gr[0][:] = []
-    # Check if we have some subgroup waiting for revisions we are not going to
-    # iterate over
-    for g in groups:
-        for r in g[0]:
-            yield r
-
- at predicate('subrepo([pattern])')
-def subrepo(repo, subset, x):
-    """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'))
-    pat = None
-    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 = util.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 pat is None:
-            return s.added or s.modified or s.removed
-
-        if s.added:
-            return 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 any(submatches(c.p1().substate.keys()))
-
-        return False
-
-    return subset.filter(matches, condrepr=('<subrepo %r>', pat))
-
-def _substringmatcher(pattern, casesensitive=True):
-    kind, pattern, matcher = util.stringmatcher(pattern,
-                                                casesensitive=casesensitive)
-    if kind == 'literal':
-        if not casesensitive:
-            pattern = encoding.lower(pattern)
-            matcher = lambda s: pattern in encoding.lower(s)
-        else:
-            matcher = lambda s: pattern in s
-    return kind, pattern, matcher
-
- at predicate('tag([name])', safe=True)
-def tag(repo, subset, x):
-    """The specified tag by name, or all tagged revisions if no name is given.
-
-    Pattern matching is supported for `name`. See
-    :hg:`help revisions.patterns`.
-    """
-    # 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 = util.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
-
- at predicate('tagged', safe=True)
-def tagged(repo, subset, x):
-    return tag(repo, subset, x)
-
- at predicate('unstable()', safe=True)
-def unstable(repo, subset, x):
-    """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
-
-
- at predicate('user(string)', safe=True)
-def user(repo, subset, x):
-    """User name contains string. The match is case-insensitive.
-
-    Pattern matching is supported for `string`. See
-    :hg:`help revisions.patterns`.
-    """
-    return author(repo, subset, x)
-
- at predicate('wdir', safe=True)
-def wdir(repo, subset, x):
-    """Working directory. (EXPERIMENTAL)"""
-    # i18n: "wdir" is a keyword
-    getargs(x, 0, 0, _("wdir takes no arguments"))
-    if node.wdirrev in subset or isinstance(subset, fullreposet):
-        return baseset([node.wdirrev])
-    return baseset()
-
-def _orderedlist(repo, subset, x):
-    s = getstring(x, "internal error")
-    if not s:
-        return baseset()
-    # remove duplicates here. it's difficult for caller to deduplicate sets
-    # because different symbols can point to the same rev.
-    cl = repo.changelog
-    ls = []
-    seen = set()
-    for t in s.split('\0'):
-        try:
-            # fast path for integer revision
-            r = int(t)
-            if str(r) != t or r not in cl:
-                raise ValueError
-            revs = [r]
-        except ValueError:
-            revs = stringset(repo, subset, t)
-
-        for r in revs:
-            if r in seen:
-                continue
-            if (r in subset
-                or r == node.nullrev and isinstance(subset, fullreposet)):
-                ls.append(r)
-            seen.add(r)
-    return baseset(ls)
-
-# for internal use
- at predicate('_list', safe=True, takeorder=True)
-def _list(repo, subset, x, order):
-    if order == followorder:
-        # slow path to take the subset order
-        return subset & _orderedlist(repo, fullreposet(repo), x)
-    else:
-        return _orderedlist(repo, subset, x)
-
-def _orderedintlist(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
- at predicate('_intlist', safe=True, takeorder=True)
-def _intlist(repo, subset, x, order):
-    if order == followorder:
-        # slow path to take the subset order
-        return subset & _orderedintlist(repo, fullreposet(repo), x)
-    else:
-        return _orderedintlist(repo, subset, x)
-
-def _orderedhexlist(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])
-
-# for internal use
- at predicate('_hexlist', safe=True, takeorder=True)
-def _hexlist(repo, subset, x, order):
-    if order == followorder:
-        # slow path to take the subset order
-        return subset & _orderedhexlist(repo, fullreposet(repo), x)
-    else:
-        return _orderedhexlist(repo, subset, x)
-
-methods = {
-    "range": rangeset,
-    "rangeall": rangeall,
-    "rangepre": rangepre,
-    "rangepost": rangepost,
-    "dagrange": dagrange,
-    "string": stringset,
-    "symbol": stringset,
-    "and": andset,
-    "or": orset,
-    "not": notset,
-    "difference": differenceset,
-    "list": listset,
-    "keyvalue": keyvaluepair,
-    "func": func,
-    "ancestor": ancestorspec,
-    "parent": parentspec,
-    "parentpost": parentpost,
-}
-
 # Constants for ordering requirement, used in _analyze():
 #
 # If 'define', any nested functions and operations can change the ordering of
@@ -2756,59 +568,6 @@ def foldconcat(tree):
 def parse(spec, lookup=None):
     return _parsewith(spec, lookup=lookup)
 
-def posttreebuilthook(tree, repo):
-    # hook for extensions to execute code on the optimized tree
-    pass
-
-def match(ui, spec, repo=None, order=defineorder):
-    """Create a matcher for a single revision spec
-
-    If order=followorder, a matcher takes the ordering specified by the input
-    set.
-    """
-    return matchany(ui, [spec], repo=repo, order=order)
-
-def matchany(ui, specs, repo=None, order=defineorder):
-    """Create a matcher that will include any revisions matching one of the
-    given specs
-
-    If order=followorder, a matcher takes the ordering specified by the input
-    set.
-    """
-    if not specs:
-        def mfunc(repo, subset=None):
-            return baseset()
-        return mfunc
-    if not all(specs):
-        raise error.ParseError(_("empty query"))
-    lookup = None
-    if repo:
-        lookup = repo.__contains__
-    if len(specs) == 1:
-        tree = parse(specs[0], lookup)
-    else:
-        tree = ('or', ('list',) + tuple(parse(s, lookup) for s in specs))
-
-    if ui:
-        tree = expandaliases(ui, tree)
-    tree = foldconcat(tree)
-    tree = analyze(tree, order)
-    tree = optimize(tree)
-    posttreebuilthook(tree, repo)
-    return makematcher(tree)
-
-def makematcher(tree):
-    """Create a matcher from an evaluatable tree"""
-    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
@@ -2923,17 +682,3 @@ def funcsused(tree):
         if tree[0] == 'func':
             funcs.add(tree[1][1])
         return funcs
-
-def loadpredicate(ui, extname, registrarobj):
-    """Load revset predicates from specified registrarobj
-    """
-    for name, func in registrarobj._table.iteritems():
-        symbols[name] = func
-        if func._safe:
-            safesymbols.add(name)
-
-# load built-in predicates explicitly to setup safesymbols
-loadpredicate(None, None, predicate)
-
-# tell hggettext to extract docstrings from these functions:
-i18nfunctions = symbols.values()
diff --git a/mercurial/scmutil.py b/mercurial/scmutil.py
--- a/mercurial/scmutil.py
+++ b/mercurial/scmutil.py
@@ -30,6 +30,7 @@ from . import (
     phases,
     pycompat,
     revset,
+    revsetlang,
     similar,
     util,
 )
@@ -890,7 +891,7 @@ def revsingle(repo, revspec, default='.'
     return repo[l.last()]
 
 def _pairspec(revspec):
-    tree = revset.parse(revspec)
+    tree = revsetlang.parse(revspec)
     return tree and tree[0] in ('range', 'rangepre', 'rangepost', 'rangeall')
 
 def revpair(repo, revs):
@@ -936,7 +937,7 @@ def revrange(repo, specs):
     revision numbers.
 
     It is assumed the revsets are already formatted. If you have arguments
-    that need to be expanded in the revset, call ``revset.formatspec()``
+    that need to be expanded in the revset, call ``revsetlang.formatspec()``
     and pass the result as an element of ``specs``.
 
     Specifying a single revset is allowed.
@@ -947,7 +948,7 @@ def revrange(repo, specs):
     allspecs = []
     for spec in specs:
         if isinstance(spec, int):
-            spec = revset.formatspec('rev(%d)', spec)
+            spec = revsetlang.formatspec('rev(%d)', spec)
         allspecs.append(spec)
     m = revset.matchany(repo.ui, allspecs, repo)
     return m(repo)
diff --git a/mercurial/templater.py b/mercurial/templater.py
--- a/mercurial/templater.py
+++ b/mercurial/templater.py
@@ -20,6 +20,7 @@ from . import (
     pycompat,
     registrar,
     revset as revsetmod,
+    revsetlang,
     templatefilters,
     templatekw,
     util,
@@ -778,7 +779,7 @@ def revset(context, mapping, args):
 
     if len(args) > 1:
         formatargs = [evalfuncarg(context, mapping, a) for a in args[1:]]
-        revs = query(revsetmod.formatspec(raw, *formatargs))
+        revs = query(revsetlang.formatspec(raw, *formatargs))
         revs = list(revs)
     else:
         revsetcache = mapping['cache'].setdefault("revsetcache", {})
diff --git a/tests/test-doctest.py b/tests/test-doctest.py
--- a/tests/test-doctest.py
+++ b/tests/test-doctest.py
@@ -28,7 +28,7 @@ testmod('mercurial.minirst')
 testmod('mercurial.patch')
 testmod('mercurial.pathutil')
 testmod('mercurial.parser')
-testmod('mercurial.revset')
+testmod('mercurial.revsetlang')
 testmod('mercurial.smartset')
 testmod('mercurial.store')
 testmod('mercurial.subrepo')
diff --git a/tests/test-glog.t b/tests/test-glog.t
--- a/tests/test-glog.t
+++ b/tests/test-glog.t
@@ -82,18 +82,18 @@ o  (0) root
   > }
 
   $ cat > printrevset.py <<EOF
-  > from mercurial import extensions, revset, commands, cmdutil
+  > from mercurial import extensions, revsetlang, commands, cmdutil
   > 
   > def uisetup(ui):
   >     def printrevset(orig, ui, repo, *pats, **opts):
   >         if opts.get('print_revset'):
   >             expr = cmdutil.getgraphlogrevs(repo, pats, opts)[1]
   >             if expr:
-  >                 tree = revset.parse(expr)
+  >                 tree = revsetlang.parse(expr)
   >             else:
   >                 tree = []
   >             ui.write('%r\n' % (opts.get('rev', []),))
-  >             ui.write(revset.prettyformat(tree) + '\n')
+  >             ui.write(revsetlang.prettyformat(tree) + '\n')
   >             return 0
   >         return orig(ui, repo, *pats, **opts)
   >     entry = extensions.wrapcommand(commands.table, 'log', printrevset)
diff --git a/tests/test-revset.t b/tests/test-revset.t
--- a/tests/test-revset.t
+++ b/tests/test-revset.t
@@ -40,6 +40,7 @@ these predicates use '\0' as a separator
   >     cmdutil,
   >     node as nodemod,
   >     revset,
+  >     revsetlang,
   >     smartset,
   > )
   > cmdtable = {}
@@ -50,13 +51,14 @@ these predicates use '\0' as a separator
   > def debugrevlistspec(ui, repo, fmt, *args, **opts):
   >     if opts['bin']:
   >         args = map(nodemod.bin, args)
-  >     expr = revset.formatspec(fmt, list(args))
+  >     expr = revsetlang.formatspec(fmt, list(args))
   >     if ui.verbose:
-  >         tree = revset.parse(expr, lookup=repo.__contains__)
-  >         ui.note(revset.prettyformat(tree), "\n")
+  >         tree = revsetlang.parse(expr, lookup=repo.__contains__)
+  >         ui.note(revsetlang.prettyformat(tree), "\n")
   >         if opts["optimize"]:
-  >             opttree = revset.optimize(revset.analyze(tree))
-  >             ui.note("* optimized:\n", revset.prettyformat(opttree), "\n")
+  >             opttree = revsetlang.optimize(revsetlang.analyze(tree))
+  >             ui.note("* optimized:\n", revsetlang.prettyformat(opttree),
+  >                     "\n")
   >     func = revset.match(ui, expr, repo)
   >     revs = func(repo)
   >     if ui.verbose:


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