templater: allow dynamically switching the default dict/list formatting

'%s' doesn't work nicely on Python 3 because many Python types don't implement
__bytes__().

mercurial/formatter.py

@@ -1,543 +1,547 b''
 # formatter.py - generic output formatting for mercurial
 #
 # Copyright 2012 Matt Mackall <[e-mail]>
 #
 # This software may be used and distributed according to the terms of the
 # GNU General Public License version 2 or any later version.
 
 """Generic output formatting for Mercurial
 
 The formatter provides API to show data in various ways. The following
 functions should be used in place of ui.write():
 
 - fm.write() for unconditional output
 - fm.condwrite() to show some extra data conditionally in plain output
 - fm.context() to provide changectx to template output
 - fm.data() to provide extra data to JSON or template output
 - fm.plain() to show raw text that isn't provided to JSON or template output
 
 To show structured data (e.g. date tuples, dicts, lists), apply fm.format*()
 beforehand so the data is converted to the appropriate data type. Use
 fm.isplain() if you need to convert or format data conditionally which isn't
 supported by the formatter API.
 
 To build nested structure (i.e. a list of dicts), use fm.nested().
 
 See also https://www.mercurial-scm.org/wiki/GenericTemplatingPlan
 
 fm.condwrite() vs 'if cond:':
 
 In most cases, use fm.condwrite() so users can selectively show the data
 in template output. If it's costly to build data, use plain 'if cond:' with
 fm.write().
 
 fm.nested() vs fm.formatdict() (or fm.formatlist()):
 
 fm.nested() should be used to form a tree structure (a list of dicts of
 lists of dicts...) which can be accessed through template keywords, e.g.
 "{foo % "{bar % {...}} {baz % {...}}"}". On the other hand, fm.formatdict()
 exports a dict-type object to template, which can be accessed by e.g.
 "{get(foo, key)}" function.
 
 Doctest helper:
 
 >>> def show(fn, verbose=False, **opts):
 ...     import sys
 ...     from . import ui as uimod
 ...     ui = uimod.ui()
 ...     ui.verbose = verbose
 ...     ui.pushbuffer()
 ...     try:
 ...         return fn(ui, ui.formatter(pycompat.sysbytes(fn.__name__),
 ...                   pycompat.byteskwargs(opts)))
 ...     finally:
 ...         print(pycompat.sysstr(ui.popbuffer()), end='')
 
 Basic example:
 
 >>> def files(ui, fm):
 ...     files = [(b'foo', 123, (0, 0)), (b'bar', 456, (1, 0))]
 ...     for f in files:
 ...         fm.startitem()
 ...         fm.write(b'path', b'%s', f[0])
 ...         fm.condwrite(ui.verbose, b'date', b'  %s',
 ...                      fm.formatdate(f[2], b'%Y-%m-%d %H:%M:%S'))
 ...         fm.data(size=f[1])
 ...         fm.plain(b'\\n')
 ...     fm.end()
 >>> show(files)
 foo
 bar
 >>> show(files, verbose=True)
 foo  1970-01-01 00:00:00
 bar  1970-01-01 00:00:01
 >>> show(files, template=b'json')
 [
  {
   "date": [0, 0],
   "path": "foo",
   "size": 123
  },
  {
   "date": [1, 0],
   "path": "bar",
   "size": 456
  }
 ]
 >>> show(files, template=b'path: {path}\\ndate: {date|rfc3339date}\\n')
 path: foo
 date: 1970-01-01T00:00:00+00:00
 path: bar
 date: 1970-01-01T00:00:01+00:00
 
 Nested example:
 
 >>> def subrepos(ui, fm):
 ...     fm.startitem()
 ...     fm.write(b'reponame', b'[%s]\\n', b'baz')
 ...     files(ui, fm.nested(b'files'))
 ...     fm.end()
 >>> show(subrepos)
 [baz]
 foo
 bar
 >>> show(subrepos, template=b'{reponame}: {join(files % "{path}", ", ")}\\n')
 baz: foo, bar
 """
 
 from __future__ import absolute_import, print_function
 
 import collections
 import contextlib
 import itertools
 import os
 
 from .i18n import _
 from .node import (
     hex,
     short,
 )
 
 from . import (
     error,
     pycompat,
     templatefilters,
     templatekw,
     templater,
     util,
 )
 from .utils import dateutil
 
 pickle = util.pickle
 
 class _nullconverter(object):
     '''convert non-primitive data types to be processed by formatter'''
 
     # set to True if context object should be stored as item
     storecontext = False
 
     @staticmethod
     def formatdate(date, fmt):
         '''convert date tuple to appropriate format'''
         return date
     @staticmethod
     def formatdict(data, key, value, fmt, sep):
         '''convert dict or key-value pairs to appropriate dict format'''
         # use plain dict instead of util.sortdict so that data can be
         # serialized as a builtin dict in pickle output
         return dict(data)
     @staticmethod
     def formatlist(data, name, fmt, sep):
         '''convert iterable to appropriate list format'''
         return list(data)
 
 class baseformatter(object):
     def __init__(self, ui, topic, opts, converter):
         self._ui = ui
         self._topic = topic
         self._style = opts.get("style")
         self._template = opts.get("template")
         self._converter = converter
         self._item = None
         # function to convert node to string suitable for this output
         self.hexfunc = hex
     def __enter__(self):
         return self
     def __exit__(self, exctype, excvalue, traceback):
         if exctype is None:
             self.end()
     def _showitem(self):
         '''show a formatted item once all data is collected'''
     def startitem(self):
         '''begin an item in the format list'''
         if self._item is not None:
             self._showitem()
         self._item = {}
     def formatdate(self, date, fmt='%a %b %d %H:%M:%S %Y %1%2'):
         '''convert date tuple to appropriate format'''
         return self._converter.formatdate(date, fmt)
-    def formatdict(self, data, key='key', value='value', fmt='%s=%s', sep=' '):
+    def formatdict(self, data, key='key', value='value', fmt=None, sep=' '):
         '''convert dict or key-value pairs to appropriate dict format'''
         return self._converter.formatdict(data, key, value, fmt, sep)
-    def formatlist(self, data, name, fmt='%s', sep=' '):
+    def formatlist(self, data, name, fmt=None, sep=' '):
         '''convert iterable to appropriate list format'''
         # name is mandatory argument for now, but it could be optional if
         # we have default template keyword, e.g. {item}
         return self._converter.formatlist(data, name, fmt, sep)
     def context(self, **ctxs):
         '''insert context objects to be used to render template keywords'''
         ctxs = pycompat.byteskwargs(ctxs)
         assert all(k == 'ctx' for k in ctxs)
         if self._converter.storecontext:
             self._item.update(ctxs)
     def data(self, **data):
         '''insert data into item that's not shown in default output'''
         data = pycompat.byteskwargs(data)
         self._item.update(data)
     def write(self, fields, deftext, *fielddata, **opts):
         '''do default text output while assigning data to item'''
         fieldkeys = fields.split()
         assert len(fieldkeys) == len(fielddata)
         self._item.update(zip(fieldkeys, fielddata))
     def condwrite(self, cond, fields, deftext, *fielddata, **opts):
         '''do conditional write (primarily for plain formatter)'''
         fieldkeys = fields.split()
         assert len(fieldkeys) == len(fielddata)
         self._item.update(zip(fieldkeys, fielddata))
     def plain(self, text, **opts):
         '''show raw text for non-templated mode'''
     def isplain(self):
         '''check for plain formatter usage'''
         return False
     def nested(self, field):
         '''sub formatter to store nested data in the specified field'''
         self._item[field] = data = []
         return _nestedformatter(self._ui, self._converter, data)
     def end(self):
         '''end output for the formatter'''
         if self._item is not None:
             self._showitem()
 
 def nullformatter(ui, topic):
     '''formatter that prints nothing'''
     return baseformatter(ui, topic, opts={}, converter=_nullconverter)
 
 class _nestedformatter(baseformatter):
     '''build sub items and store them in the parent formatter'''
     def __init__(self, ui, converter, data):
         baseformatter.__init__(self, ui, topic='', opts={}, converter=converter)
         self._data = data
     def _showitem(self):
         self._data.append(self._item)
 
 def _iteritems(data):
     '''iterate key-value pairs in stable order'''
     if isinstance(data, dict):
         return sorted(data.iteritems())
     return data
 
 class _plainconverter(object):
     '''convert non-primitive data types to text'''
 
     storecontext = False
 
     @staticmethod
     def formatdate(date, fmt):
         '''stringify date tuple in the given format'''
         return dateutil.datestr(date, fmt)
     @staticmethod
     def formatdict(data, key, value, fmt, sep):
         '''stringify key-value pairs separated by sep'''
+        if fmt is None:
+            fmt = '%s=%s'
         return sep.join(fmt % (k, v) for k, v in _iteritems(data))
     @staticmethod
     def formatlist(data, name, fmt, sep):
         '''stringify iterable separated by sep'''
+        if fmt is None:
+            fmt = '%s'
         return sep.join(fmt % e for e in data)
 
 class plainformatter(baseformatter):
     '''the default text output scheme'''
     def __init__(self, ui, out, topic, opts):
         baseformatter.__init__(self, ui, topic, opts, _plainconverter)
         if ui.debugflag:
             self.hexfunc = hex
         else:
             self.hexfunc = short
         if ui is out:
             self._write = ui.write
         else:
             self._write = lambda s, **opts: out.write(s)
     def startitem(self):
         pass
     def data(self, **data):
         pass
     def write(self, fields, deftext, *fielddata, **opts):
         self._write(deftext % fielddata, **opts)
     def condwrite(self, cond, fields, deftext, *fielddata, **opts):
         '''do conditional write'''
         if cond:
             self._write(deftext % fielddata, **opts)
     def plain(self, text, **opts):
         self._write(text, **opts)
     def isplain(self):
         return True
     def nested(self, field):
         # nested data will be directly written to ui
         return self
     def end(self):
         pass
 
 class debugformatter(baseformatter):
     def __init__(self, ui, out, topic, opts):
         baseformatter.__init__(self, ui, topic, opts, _nullconverter)
         self._out = out
         self._out.write("%s = [\n" % self._topic)
     def _showitem(self):
         self._out.write('    %s,\n' % pycompat.byterepr(self._item))
     def end(self):
         baseformatter.end(self)
         self._out.write("]\n")
 
 class pickleformatter(baseformatter):
     def __init__(self, ui, out, topic, opts):
         baseformatter.__init__(self, ui, topic, opts, _nullconverter)
         self._out = out
         self._data = []
     def _showitem(self):
         self._data.append(self._item)
     def end(self):
         baseformatter.end(self)
         self._out.write(pickle.dumps(self._data))
 
 class jsonformatter(baseformatter):
     def __init__(self, ui, out, topic, opts):
         baseformatter.__init__(self, ui, topic, opts, _nullconverter)
         self._out = out
         self._out.write("[")
         self._first = True
     def _showitem(self):
         if self._first:
             self._first = False
         else:
             self._out.write(",")
 
         self._out.write("\n {\n")
         first = True
         for k, v in sorted(self._item.items()):
             if first:
                 first = False
             else:
                 self._out.write(",\n")
             u = templatefilters.json(v, paranoid=False)
             self._out.write('  "%s": %s' % (k, u))
         self._out.write("\n }")
     def end(self):
         baseformatter.end(self)
         self._out.write("\n]\n")
 
 class _templateconverter(object):
     '''convert non-primitive data types to be processed by templater'''
 
     storecontext = True
 
     @staticmethod
     def formatdate(date, fmt):
         '''return date tuple'''
         return date
     @staticmethod
     def formatdict(data, key, value, fmt, sep):
         '''build object that can be evaluated as either plain string or dict'''
         data = util.sortdict(_iteritems(data))
         def f():
             yield _plainconverter.formatdict(data, key, value, fmt, sep)
         return templatekw.hybriddict(data, key=key, value=value, fmt=fmt, gen=f)
     @staticmethod
     def formatlist(data, name, fmt, sep):
         '''build object that can be evaluated as either plain string or list'''
         data = list(data)
         def f():
             yield _plainconverter.formatlist(data, name, fmt, sep)
         return templatekw.hybridlist(data, name=name, fmt=fmt, gen=f)
 
 class templateformatter(baseformatter):
     def __init__(self, ui, out, topic, opts):
         baseformatter.__init__(self, ui, topic, opts, _templateconverter)
         self._out = out
         spec = lookuptemplate(ui, topic, opts.get('template', ''))
         self._tref = spec.ref
         self._t = loadtemplater(ui, spec, defaults=templatekw.keywords,
                                 resources=templateresources(ui),
                                 cache=templatekw.defaulttempl)
         self._parts = templatepartsmap(spec, self._t,
                                        ['docheader', 'docfooter', 'separator'])
         self._counter = itertools.count()
         self._renderitem('docheader', {})
 
     def _showitem(self):
         item = self._item.copy()
         item['index'] = index = next(self._counter)
         if index > 0:
             self._renderitem('separator', {})
         self._renderitem(self._tref, item)
 
     def _renderitem(self, part, item):
         if part not in self._parts:
             return
         ref = self._parts[part]
 
         # TODO: add support for filectx
         props = {}
         # explicitly-defined fields precede templatekw
         props.update(item)
         if 'ctx' in item:
             # but template resources must be always available
             props['repo'] = props['ctx'].repo()
             props['revcache'] = {}
         props = pycompat.strkwargs(props)
         g = self._t(ref, **props)
         self._out.write(templater.stringify(g))
 
     def end(self):
         baseformatter.end(self)
         self._renderitem('docfooter', {})
 
 templatespec = collections.namedtuple(r'templatespec',
                                       r'ref tmpl mapfile')
 
 def lookuptemplate(ui, topic, tmpl):
     """Find the template matching the given -T/--template spec 'tmpl'
 
     'tmpl' can be any of the following:
 
      - a literal template (e.g. '{rev}')
      - a map-file name or path (e.g. 'changelog')
      - a reference to [templates] in config file
      - a path to raw template file
 
     A map file defines a stand-alone template environment. If a map file
     selected, all templates defined in the file will be loaded, and the
     template matching the given topic will be rendered. Aliases won't be
     loaded from user config, but from the map file.
 
     If no map file selected, all templates in [templates] section will be
     available as well as aliases in [templatealias].
     """
 
     # looks like a literal template?
     if '{' in tmpl:
         return templatespec('', tmpl, None)
 
     # perhaps a stock style?
     if not os.path.split(tmpl)[0]:
         mapname = (templater.templatepath('map-cmdline.' + tmpl)
                    or templater.templatepath(tmpl))
         if mapname and os.path.isfile(mapname):
             return templatespec(topic, None, mapname)
 
     # perhaps it's a reference to [templates]
     if ui.config('templates', tmpl):
         return templatespec(tmpl, None, None)
 
     if tmpl == 'list':
         ui.write(_("available styles: %s\n") % templater.stylelist())
         raise error.Abort(_("specify a template"))
 
     # perhaps it's a path to a map or a template
     if ('/' in tmpl or '\\' in tmpl) and os.path.isfile(tmpl):
         # is it a mapfile for a style?
         if os.path.basename(tmpl).startswith("map-"):
             return templatespec(topic, None, os.path.realpath(tmpl))
         with util.posixfile(tmpl, 'rb') as f:
             tmpl = f.read()
         return templatespec('', tmpl, None)
 
     # constant string?
     return templatespec('', tmpl, None)
 
 def templatepartsmap(spec, t, partnames):
     """Create a mapping of {part: ref}"""
     partsmap = {spec.ref: spec.ref}  # initial ref must exist in t
     if spec.mapfile:
         partsmap.update((p, p) for p in partnames if p in t)
     elif spec.ref:
         for part in partnames:
             ref = '%s:%s' % (spec.ref, part)  # select config sub-section
             if ref in t:
                 partsmap[part] = ref
     return partsmap
 
 def loadtemplater(ui, spec, defaults=None, resources=None, cache=None):
     """Create a templater from either a literal template or loading from
     a map file"""
     assert not (spec.tmpl and spec.mapfile)
     if spec.mapfile:
         frommapfile = templater.templater.frommapfile
         return frommapfile(spec.mapfile, defaults=defaults, resources=resources,
                            cache=cache)
     return maketemplater(ui, spec.tmpl, defaults=defaults, resources=resources,
                          cache=cache)
 
 def maketemplater(ui, tmpl, defaults=None, resources=None, cache=None):
     """Create a templater from a string template 'tmpl'"""
     aliases = ui.configitems('templatealias')
     t = templater.templater(defaults=defaults, resources=resources,
                             cache=cache, aliases=aliases)
     t.cache.update((k, templater.unquotestring(v))
                    for k, v in ui.configitems('templates'))
     if tmpl:
         t.cache[''] = tmpl
     return t
 
 def templateresources(ui, repo=None):
     """Create a dict of template resources designed for the default templatekw
     and function"""
     return {
         'cache': {},  # for templatekw/funcs to store reusable data
         'ctx': None,
         'repo': repo,
         'revcache': None,  # per-ctx cache; set later
         'ui': ui,
     }
 
 def formatter(ui, out, topic, opts):
     template = opts.get("template", "")
     if template == "json":
         return jsonformatter(ui, out, topic, opts)
     elif template == "pickle":
         return pickleformatter(ui, out, topic, opts)
     elif template == "debug":
         return debugformatter(ui, out, topic, opts)
     elif template != "":
         return templateformatter(ui, out, topic, opts)
     # developer config: ui.formatdebug
     elif ui.configbool('ui', 'formatdebug'):
         return debugformatter(ui, out, topic, opts)
     # deprecated config: ui.formatjson
     elif ui.configbool('ui', 'formatjson'):
         return jsonformatter(ui, out, topic, opts)
     return plainformatter(ui, out, topic, opts)
 
 @contextlib.contextmanager
 def openformatter(ui, filename, topic, opts):
     """Create a formatter that writes outputs to the specified file
 
     Must be invoked using the 'with' statement.
     """
     with util.posixfile(filename, 'wb') as out:
         with formatter(ui, out, topic, opts) as fm:
             yield fm
 
 @contextlib.contextmanager
 def _neverending(fm):
     yield fm
 
 def maybereopen(fm, filename, opts):
     """Create a formatter backed by file if filename specified, else return
     the given formatter
 
     Must be invoked using the 'with' statement. This will never call fm.end()
     of the given formatter.
     """
     if filename:
         return openformatter(fm._ui, filename, fm._topic, opts)
     else:
         return _neverending(fm)

mercurial/templatekw.py

@@ -1,995 +1,999 b''
 # templatekw.py - common changeset template keywords
 #
 # Copyright 2005-2009 Matt Mackall <[e-mail]>
 #
 # This software may be used and distributed according to the terms of the
 # GNU General Public License version 2 or any later version.
 
 from __future__ import absolute_import
 
 from .i18n import _
 from .node import (
     hex,
     nullid,
 )
 
 from . import (
     encoding,
     error,
     hbisect,
     i18n,
     obsutil,
     patch,
     pycompat,
     registrar,
     scmutil,
     util,
 )
 
 class _hybrid(object):
     """Wrapper for list or dict to support legacy template
 
     This class allows us to handle both:
     - "{files}" (legacy command-line-specific list hack) and
     - "{files % '{file}\n'}" (hgweb-style with inlining and function support)
     and to access raw values:
     - "{ifcontains(file, files, ...)}", "{ifcontains(key, extras, ...)}"
     - "{get(extras, key)}"
     - "{files|json}"
     """
 
     def __init__(self, gen, values, makemap, joinfmt, keytype=None):
         if gen is not None:
             self.gen = gen  # generator or function returning generator
         self._values = values
         self._makemap = makemap
         self.joinfmt = joinfmt
         self.keytype = keytype  # hint for 'x in y' where type(x) is unresolved
     def gen(self):
         """Default generator to stringify this as {join(self, ' ')}"""
         for i, x in enumerate(self._values):
             if i > 0:
                 yield ' '
             yield self.joinfmt(x)
     def itermaps(self):
         makemap = self._makemap
         for x in self._values:
             yield makemap(x)
     def __contains__(self, x):
         return x in self._values
     def __getitem__(self, key):
         return self._values[key]
     def __len__(self):
         return len(self._values)
     def __iter__(self):
         return iter(self._values)
     def __getattr__(self, name):
         if name not in (r'get', r'items', r'iteritems', r'iterkeys',
                         r'itervalues', r'keys', r'values'):
             raise AttributeError(name)
         return getattr(self._values, name)
 
 class _mappable(object):
     """Wrapper for non-list/dict object to support map operation
 
     This class allows us to handle both:
     - "{manifest}"
     - "{manifest % '{rev}:{node}'}"
     - "{manifest.rev}"
 
     Unlike a _hybrid, this does not simulate the behavior of the underling
     value. Use unwrapvalue() or unwraphybrid() to obtain the inner object.
     """
 
     def __init__(self, gen, key, value, makemap):
         if gen is not None:
             self.gen = gen  # generator or function returning generator
         self._key = key
         self._value = value  # may be generator of strings
         self._makemap = makemap
 
     def gen(self):
         yield pycompat.bytestr(self._value)
 
     def tomap(self):
         return self._makemap(self._key)
 
     def itermaps(self):
         yield self.tomap()
 
-def hybriddict(data, key='key', value='value', fmt='%s=%s', gen=None):
+def hybriddict(data, key='key', value='value', fmt=None, gen=None):
     """Wrap data to support both dict-like and string-like operations"""
+    if fmt is None:
+        fmt = '%s=%s'
     return _hybrid(gen, data, lambda k: {key: k, value: data[k]},
                    lambda k: fmt % (k, data[k]))
 
-def hybridlist(data, name, fmt='%s', gen=None):
+def hybridlist(data, name, fmt=None, gen=None):
     """Wrap data to support both list-like and string-like operations"""
+    if fmt is None:
+        fmt = '%s'
     return _hybrid(gen, data, lambda x: {name: x}, lambda x: fmt % x)
 
 def unwraphybrid(thing):
     """Return an object which can be stringified possibly by using a legacy
     template"""
     gen = getattr(thing, 'gen', None)
     if gen is None:
         return thing
     if callable(gen):
         return gen()
     return gen
 
 def unwrapvalue(thing):
     """Move the inner value object out of the wrapper"""
     if not util.safehasattr(thing, '_value'):
         return thing
     return thing._value
 
 def wraphybridvalue(container, key, value):
     """Wrap an element of hybrid container to be mappable
 
     The key is passed to the makemap function of the given container, which
     should be an item generated by iter(container).
     """
     makemap = getattr(container, '_makemap', None)
     if makemap is None:
         return value
     if util.safehasattr(value, '_makemap'):
         # a nested hybrid list/dict, which has its own way of map operation
         return value
     return _mappable(None, key, value, makemap)
 
 def compatdict(context, mapping, name, data, key='key', value='value',
-               fmt='%s=%s', plural=None, separator=' '):
+               fmt=None, plural=None, separator=' '):
     """Wrap data like hybriddict(), but also supports old-style list template
 
     This exists for backward compatibility with the old-style template. Use
     hybriddict() for new template keywords.
     """
     c = [{key: k, value: v} for k, v in data.iteritems()]
     t = context.resource(mapping, 'templ')
     f = _showlist(name, c, t, mapping, plural, separator)
     return hybriddict(data, key=key, value=value, fmt=fmt, gen=f)
 
-def compatlist(context, mapping, name, data, element=None, fmt='%s',
+def compatlist(context, mapping, name, data, element=None, fmt=None,
                plural=None, separator=' '):
     """Wrap data like hybridlist(), but also supports old-style list template
 
     This exists for backward compatibility with the old-style template. Use
     hybridlist() for new template keywords.
     """
     t = context.resource(mapping, 'templ')
     f = _showlist(name, data, t, mapping, plural, separator)
     return hybridlist(data, name=element or name, fmt=fmt, gen=f)
 
 def showdict(name, data, mapping, plural=None, key='key', value='value',
-             fmt='%s=%s', separator=' '):
+             fmt=None, separator=' '):
     ui = mapping.get('ui')
     if ui:
         ui.deprecwarn("templatekw.showdict() is deprecated, use compatdict()",
                       '4.6')
     c = [{key: k, value: v} for k, v in data.iteritems()]
     f = _showlist(name, c, mapping['templ'], mapping, plural, separator)
     return hybriddict(data, key=key, value=value, fmt=fmt, gen=f)
 
 def showlist(name, values, mapping, plural=None, element=None, separator=' '):
     ui = mapping.get('ui')
     if ui:
         ui.deprecwarn("templatekw.showlist() is deprecated, use compatlist()",
                       '4.6')
     if not element:
         element = name
     f = _showlist(name, values, mapping['templ'], mapping, plural, separator)
     return hybridlist(values, name=element, gen=f)
 
 def _showlist(name, values, templ, mapping, plural=None, separator=' '):
     '''expand set of values.
     name is name of key in template map.
     values is list of strings or dicts.
     plural is plural of name, if not simply name + 's'.
     separator is used to join values as a string
 
     expansion works like this, given name 'foo'.
 
     if values is empty, expand 'no_foos'.
 
     if 'foo' not in template map, return values as a string,
     joined by 'separator'.
 
     expand 'start_foos'.
 
     for each value, expand 'foo'. if 'last_foo' in template
     map, expand it instead of 'foo' for last key.
 
     expand 'end_foos'.
     '''
     strmapping = pycompat.strkwargs(mapping)
     if not plural:
         plural = name + 's'
     if not values:
         noname = 'no_' + plural
         if noname in templ:
             yield templ(noname, **strmapping)
         return
     if name not in templ:
         if isinstance(values[0], bytes):
             yield separator.join(values)
         else:
             for v in values:
                 r = dict(v)
                 r.update(mapping)
                 yield r
         return
     startname = 'start_' + plural
     if startname in templ:
         yield templ(startname, **strmapping)
     vmapping = mapping.copy()
     def one(v, tag=name):
         try:
             vmapping.update(v)
         # Python 2 raises ValueError if the type of v is wrong. Python
         # 3 raises TypeError.
         except (AttributeError, TypeError, ValueError):
             try:
                 # Python 2 raises ValueError trying to destructure an e.g.
                 # bytes. Python 3 raises TypeError.
                 for a, b in v:
                     vmapping[a] = b
             except (TypeError, ValueError):
                 vmapping[name] = v
         return templ(tag, **pycompat.strkwargs(vmapping))
     lastname = 'last_' + name
     if lastname in templ:
         last = values.pop()
     else:
         last = None
     for v in values:
         yield one(v)
     if last is not None:
         yield one(last, tag=lastname)
     endname = 'end_' + plural
     if endname in templ:
         yield templ(endname, **strmapping)
 
 def getlatesttags(context, mapping, pattern=None):
     '''return date, distance and name for the latest tag of rev'''
     repo = context.resource(mapping, 'repo')
     ctx = context.resource(mapping, 'ctx')
     cache = context.resource(mapping, 'cache')
 
     cachename = 'latesttags'
     if pattern is not None:
         cachename += '-' + pattern
         match = util.stringmatcher(pattern)[2]
     else:
         match = util.always
 
     if cachename not in cache:
         # Cache mapping from rev to a tuple with tag date, tag
         # distance and tag name
         cache[cachename] = {-1: (0, 0, ['null'])}
     latesttags = cache[cachename]
 
     rev = ctx.rev()
     todo = [rev]
     while todo:
         rev = todo.pop()
         if rev in latesttags:
             continue
         ctx = repo[rev]
         tags = [t for t in ctx.tags()
                 if (repo.tagtype(t) and repo.tagtype(t) != 'local'
                     and match(t))]
         if tags:
             latesttags[rev] = ctx.date()[0], 0, [t for t in sorted(tags)]
             continue
         try:
             ptags = [latesttags[p.rev()] for p in ctx.parents()]
             if len(ptags) > 1:
                 if ptags[0][2] == ptags[1][2]:
                     # The tuples are laid out so the right one can be found by
                     # comparison in this case.
                     pdate, pdist, ptag = max(ptags)
                 else:
                     def key(x):
                         changessincetag = len(repo.revs('only(%d, %s)',
                                                         ctx.rev(), x[2][0]))
                         # Smallest number of changes since tag wins. Date is
                         # used as tiebreaker.
                         return [-changessincetag, x[0]]
                     pdate, pdist, ptag = max(ptags, key=key)
             else:
                 pdate, pdist, ptag = ptags[0]
         except KeyError:
             # Cache miss - recurse
             todo.append(rev)
             todo.extend(p.rev() for p in ctx.parents())
             continue
         latesttags[rev] = pdate, pdist + 1, ptag
     return latesttags[rev]
 
 def getrenamedfn(repo, endrev=None):
     rcache = {}
     if endrev is None:
         endrev = len(repo)
 
     def getrenamed(fn, rev):
         '''looks up all renames for a file (up to endrev) the first
         time the file is given. It indexes on the changerev and only
         parses the manifest if linkrev != changerev.
         Returns rename info for fn at changerev rev.'''
         if fn not in rcache:
             rcache[fn] = {}
             fl = repo.file(fn)
             for i in fl:
                 lr = fl.linkrev(i)
                 renamed = fl.renamed(fl.node(i))
                 rcache[fn][lr] = renamed
                 if lr >= endrev:
                     break
         if rev in rcache[fn]:
             return rcache[fn][rev]
 
         # If linkrev != rev (i.e. rev not found in rcache) fallback to
         # filectx logic.
         try:
             return repo[rev][fn].renamed()
         except error.LookupError:
             return None
 
     return getrenamed
 
 def getlogcolumns():
     """Return a dict of log column labels"""
     _ = pycompat.identity  # temporarily disable gettext
     # i18n: column positioning for "hg log"
     columns = _('bookmark:    %s\n'
                 'branch:      %s\n'
                 'changeset:   %s\n'
                 'copies:      %s\n'
                 'date:        %s\n'
                 'extra:       %s=%s\n'
                 'files+:      %s\n'
                 'files-:      %s\n'
                 'files:       %s\n'
                 'instability: %s\n'
                 'manifest:    %s\n'
                 'obsolete:    %s\n'
                 'parent:      %s\n'
                 'phase:       %s\n'
                 'summary:     %s\n'
                 'tag:         %s\n'
                 'user:        %s\n')
     return dict(zip([s.split(':', 1)[0] for s in columns.splitlines()],
                     i18n._(columns).splitlines(True)))
 
 # default templates internally used for rendering of lists
 defaulttempl = {
     'parent': '{rev}:{node|formatnode} ',
     'manifest': '{rev}:{node|formatnode}',
     'file_copy': '{name} ({source})',
     'envvar': '{key}={value}',
     'extra': '{key}={value|stringescape}'
 }
 # filecopy is preserved for compatibility reasons
 defaulttempl['filecopy'] = defaulttempl['file_copy']
 
 # keywords are callables (see registrar.templatekeyword for details)
 keywords = {}
 templatekeyword = registrar.templatekeyword(keywords)
 
 @templatekeyword('author', requires={'ctx'})
 def showauthor(context, mapping):
     """String. The unmodified author of the changeset."""
     ctx = context.resource(mapping, 'ctx')
     return ctx.user()
 
 @templatekeyword('bisect', requires={'repo', 'ctx'})
 def showbisect(context, mapping):
     """String. The changeset bisection status."""
     repo = context.resource(mapping, 'repo')
     ctx = context.resource(mapping, 'ctx')
     return hbisect.label(repo, ctx.node())
 
 @templatekeyword('branch', requires={'ctx'})
 def showbranch(context, mapping):
     """String. The name of the branch on which the changeset was
     committed.
     """
     ctx = context.resource(mapping, 'ctx')
     return ctx.branch()
 
 @templatekeyword('branches', requires={'ctx', 'templ'})
 def showbranches(context, mapping):
     """List of strings. The name of the branch on which the
     changeset was committed. Will be empty if the branch name was
     default. (DEPRECATED)
     """
     ctx = context.resource(mapping, 'ctx')
     branch = ctx.branch()
     if branch != 'default':
         return compatlist(context, mapping, 'branch', [branch],
                           plural='branches')
     return compatlist(context, mapping, 'branch', [], plural='branches')
 
 @templatekeyword('bookmarks', requires={'repo', 'ctx', 'templ'})
 def showbookmarks(context, mapping):
     """List of strings. Any bookmarks associated with the
     changeset. Also sets 'active', the name of the active bookmark.
     """
     repo = context.resource(mapping, 'repo')
     ctx = context.resource(mapping, 'ctx')
     templ = context.resource(mapping, 'templ')
     bookmarks = ctx.bookmarks()
     active = repo._activebookmark
     makemap = lambda v: {'bookmark': v, 'active': active, 'current': active}
     f = _showlist('bookmark', bookmarks, templ, mapping)
     return _hybrid(f, bookmarks, makemap, pycompat.identity)
 
 @templatekeyword('children', requires={'ctx', 'templ'})
 def showchildren(context, mapping):
     """List of strings. The children of the changeset."""
     ctx = context.resource(mapping, 'ctx')
     childrevs = ['%d:%s' % (cctx.rev(), cctx) for cctx in ctx.children()]
     return compatlist(context, mapping, 'children', childrevs, element='child')
 
 # Deprecated, but kept alive for help generation a purpose.
 @templatekeyword('currentbookmark', requires={'repo', 'ctx'})
 def showcurrentbookmark(context, mapping):
     """String. The active bookmark, if it is associated with the changeset.
     (DEPRECATED)"""
     return showactivebookmark(context, mapping)
 
 @templatekeyword('activebookmark', requires={'repo', 'ctx'})
 def showactivebookmark(context, mapping):
     """String. The active bookmark, if it is associated with the changeset."""
     repo = context.resource(mapping, 'repo')
     ctx = context.resource(mapping, 'ctx')
     active = repo._activebookmark
     if active and active in ctx.bookmarks():
         return active
     return ''
 
 @templatekeyword('date', requires={'ctx'})
 def showdate(context, mapping):
     """Date information. The date when the changeset was committed."""
     ctx = context.resource(mapping, 'ctx')
     return ctx.date()
 
 @templatekeyword('desc', requires={'ctx'})
 def showdescription(context, mapping):
     """String. The text of the changeset description."""
     ctx = context.resource(mapping, 'ctx')
     s = ctx.description()
     if isinstance(s, encoding.localstr):
         # try hard to preserve utf-8 bytes
         return encoding.tolocal(encoding.fromlocal(s).strip())
     else:
         return s.strip()
 
 @templatekeyword('diffstat', requires={'ctx'})
 def showdiffstat(context, mapping):
     """String. Statistics of changes with the following format:
     "modified files: +added/-removed lines"
     """
     ctx = context.resource(mapping, 'ctx')
     stats = patch.diffstatdata(util.iterlines(ctx.diff(noprefix=False)))
     maxname, maxtotal, adds, removes, binary = patch.diffstatsum(stats)
     return '%d: +%d/-%d' % (len(stats), adds, removes)
 
 @templatekeyword('envvars', requires={'ui', 'templ'})
 def showenvvars(context, mapping):
     """A dictionary of environment variables. (EXPERIMENTAL)"""
     ui = context.resource(mapping, 'ui')
     env = ui.exportableenviron()
     env = util.sortdict((k, env[k]) for k in sorted(env))
     return compatdict(context, mapping, 'envvar', env, plural='envvars')
 
 @templatekeyword('extras', requires={'ctx', 'templ'})
 def showextras(context, mapping):
     """List of dicts with key, value entries of the 'extras'
     field of this changeset."""
     ctx = context.resource(mapping, 'ctx')
     templ = context.resource(mapping, 'templ')
     extras = ctx.extra()
     extras = util.sortdict((k, extras[k]) for k in sorted(extras))
     makemap = lambda k: {'key': k, 'value': extras[k]}
     c = [makemap(k) for k in extras]
     f = _showlist('extra', c, templ, mapping, plural='extras')
     return _hybrid(f, extras, makemap,
                    lambda k: '%s=%s' % (k, util.escapestr(extras[k])))
 
 def _showfilesbystat(context, mapping, name, index):
     repo = context.resource(mapping, 'repo')
     ctx = context.resource(mapping, 'ctx')
     revcache = context.resource(mapping, 'revcache')
     if 'files' not in revcache:
         revcache['files'] = repo.status(ctx.p1(), ctx)[:3]
     files = revcache['files'][index]
     return compatlist(context, mapping, name, files, element='file')
 
 @templatekeyword('file_adds', requires={'repo', 'ctx', 'revcache', 'templ'})
 def showfileadds(context, mapping):
     """List of strings. Files added by this changeset."""
     return _showfilesbystat(context, mapping, 'file_add', 1)
 
 @templatekeyword('file_copies',
                  requires={'repo', 'ctx', 'cache', 'revcache', 'templ'})
 def showfilecopies(context, mapping):
     """List of strings. Files copied in this changeset with
     their sources.
     """
     repo = context.resource(mapping, 'repo')
     ctx = context.resource(mapping, 'ctx')
     cache = context.resource(mapping, 'cache')
     copies = context.resource(mapping, 'revcache').get('copies')
     if copies is None:
         if 'getrenamed' not in cache:
             cache['getrenamed'] = getrenamedfn(repo)
         copies = []
         getrenamed = cache['getrenamed']
         for fn in ctx.files():
             rename = getrenamed(fn, ctx.rev())
             if rename:
                 copies.append((fn, rename[0]))
 
     copies = util.sortdict(copies)
     return compatdict(context, mapping, 'file_copy', copies,
                       key='name', value='source', fmt='%s (%s)',
                       plural='file_copies')
 
 # showfilecopiesswitch() displays file copies only if copy records are
 # provided before calling the templater, usually with a --copies
 # command line switch.
 @templatekeyword('file_copies_switch', requires={'revcache', 'templ'})
 def showfilecopiesswitch(context, mapping):
     """List of strings. Like "file_copies" but displayed
     only if the --copied switch is set.
     """
     copies = context.resource(mapping, 'revcache').get('copies') or []
     copies = util.sortdict(copies)
     return compatdict(context, mapping, 'file_copy', copies,
                       key='name', value='source', fmt='%s (%s)',
                       plural='file_copies')
 
 @templatekeyword('file_dels', requires={'repo', 'ctx', 'revcache', 'templ'})
 def showfiledels(context, mapping):
     """List of strings. Files removed by this changeset."""
     return _showfilesbystat(context, mapping, 'file_del', 2)
 
 @templatekeyword('file_mods', requires={'repo', 'ctx', 'revcache', 'templ'})
 def showfilemods(context, mapping):
     """List of strings. Files modified by this changeset."""
     return _showfilesbystat(context, mapping, 'file_mod', 0)
 
 @templatekeyword('files', requires={'ctx', 'templ'})
 def showfiles(context, mapping):
     """List of strings. All files modified, added, or removed by this
     changeset.
     """
     ctx = context.resource(mapping, 'ctx')
     return compatlist(context, mapping, 'file', ctx.files())
 
 @templatekeyword('graphnode', requires={'repo', 'ctx'})
 def showgraphnode(context, mapping):
     """String. The character representing the changeset node in an ASCII
     revision graph."""
     repo = context.resource(mapping, 'repo')
     ctx = context.resource(mapping, 'ctx')
     return getgraphnode(repo, ctx)
 
 def getgraphnode(repo, ctx):
     wpnodes = repo.dirstate.parents()
     if wpnodes[1] == nullid:
         wpnodes = wpnodes[:1]
     if ctx.node() in wpnodes:
         return '@'
     elif ctx.obsolete():
         return 'x'
     elif ctx.isunstable():
         return '*'
     elif ctx.closesbranch():
         return '_'
     else:
         return 'o'
 
 @templatekeyword('graphwidth', requires=())
 def showgraphwidth(context, mapping):
     """Integer. The width of the graph drawn by 'log --graph' or zero."""
     # just hosts documentation; should be overridden by template mapping
     return 0
 
 @templatekeyword('index', requires=())
 def showindex(context, mapping):
     """Integer. The current iteration of the loop. (0 indexed)"""
     # just hosts documentation; should be overridden by template mapping
     raise error.Abort(_("can't use index in this context"))
 
 @templatekeyword('latesttag', requires={'repo', 'ctx', 'cache', 'templ'})
 def showlatesttag(context, mapping):
     """List of strings. The global tags on the most recent globally
     tagged ancestor of this changeset.  If no such tags exist, the list
     consists of the single string "null".
     """
     return showlatesttags(context, mapping, None)
 
 def showlatesttags(context, mapping, pattern):
     """helper method for the latesttag keyword and function"""
     latesttags = getlatesttags(context, mapping, pattern)
 
     # latesttag[0] is an implementation detail for sorting csets on different
     # branches in a stable manner- it is the date the tagged cset was created,
     # not the date the tag was created.  Therefore it isn't made visible here.
     makemap = lambda v: {
         'changes': _showchangessincetag,
         'distance': latesttags[1],
         'latesttag': v,   # BC with {latesttag % '{latesttag}'}
         'tag': v
     }
 
     tags = latesttags[2]
     templ = context.resource(mapping, 'templ')
     f = _showlist('latesttag', tags, templ, mapping, separator=':')
     return _hybrid(f, tags, makemap, pycompat.identity)
 
 @templatekeyword('latesttagdistance', requires={'repo', 'ctx', 'cache'})
 def showlatesttagdistance(context, mapping):
     """Integer. Longest path to the latest tag."""
     return getlatesttags(context, mapping)[1]
 
 @templatekeyword('changessincelatesttag', requires={'repo', 'ctx', 'cache'})
 def showchangessincelatesttag(context, mapping):
     """Integer. All ancestors not in the latest tag."""
     mapping = mapping.copy()
     mapping['tag'] = getlatesttags(context, mapping)[2][0]
     return _showchangessincetag(context, mapping)
 
 def _showchangessincetag(context, mapping):
     repo = context.resource(mapping, 'repo')
     ctx = context.resource(mapping, 'ctx')
     offset = 0
     revs = [ctx.rev()]
     tag = context.symbol(mapping, 'tag')
 
     # The only() revset doesn't currently support wdir()
     if ctx.rev() is None:
         offset = 1
         revs = [p.rev() for p in ctx.parents()]
 
     return len(repo.revs('only(%ld, %s)', revs, tag)) + offset
 
 # teach templater latesttags.changes is switched to (context, mapping) API
 _showchangessincetag._requires = {'repo', 'ctx'}
 
 @templatekeyword('manifest', requires={'repo', 'ctx', 'templ'})
 def showmanifest(context, mapping):
     repo = context.resource(mapping, 'repo')
     ctx = context.resource(mapping, 'ctx')
     templ = context.resource(mapping, 'templ')
     mnode = ctx.manifestnode()
     if mnode is None:
         # just avoid crash, we might want to use the 'ff...' hash in future
         return
     mrev = repo.manifestlog._revlog.rev(mnode)
     mhex = hex(mnode)
     mapping = mapping.copy()
     mapping.update({'rev': mrev, 'node': mhex})
     f = templ('manifest', **pycompat.strkwargs(mapping))
     # TODO: perhaps 'ctx' should be dropped from mapping because manifest
     # rev and node are completely different from changeset's.
     return _mappable(f, None, f, lambda x: {'rev': mrev, 'node': mhex})
 
 @templatekeyword('obsfate', requires={'ui', 'repo', 'ctx', 'templ'})
 def showobsfate(context, mapping):
     # this function returns a list containing pre-formatted obsfate strings.
     #
     # This function will be replaced by templates fragments when we will have
     # the verbosity templatekw available.
     succsandmarkers = showsuccsandmarkers(context, mapping)
 
     ui = context.resource(mapping, 'ui')
     values = []
 
     for x in succsandmarkers:
         values.append(obsutil.obsfateprinter(x['successors'], x['markers'], ui))
 
     return compatlist(context, mapping, "fate", values)
 
 def shownames(context, mapping, namespace):
     """helper method to generate a template keyword for a namespace"""
     repo = context.resource(mapping, 'repo')
     ctx = context.resource(mapping, 'ctx')
     ns = repo.names[namespace]
     names = ns.names(repo, ctx.node())
     return compatlist(context, mapping, ns.templatename, names,
                       plural=namespace)
 
 @templatekeyword('namespaces', requires={'repo', 'ctx', 'templ'})
 def shownamespaces(context, mapping):
     """Dict of lists. Names attached to this changeset per
     namespace."""
     repo = context.resource(mapping, 'repo')
     ctx = context.resource(mapping, 'ctx')
     templ = context.resource(mapping, 'templ')
 
     namespaces = util.sortdict()
     def makensmapfn(ns):
         # 'name' for iterating over namespaces, templatename for local reference
         return lambda v: {'name': v, ns.templatename: v}
 
     for k, ns in repo.names.iteritems():
         names = ns.names(repo, ctx.node())
         f = _showlist('name', names, templ, mapping)
         namespaces[k] = _hybrid(f, names, makensmapfn(ns), pycompat.identity)
 
     f = _showlist('namespace', list(namespaces), templ, mapping)
 
     def makemap(ns):
         return {
             'namespace': ns,
             'names': namespaces[ns],
             'builtin': repo.names[ns].builtin,
             'colorname': repo.names[ns].colorname,
         }
 
     return _hybrid(f, namespaces, makemap, pycompat.identity)
 
 @templatekeyword('node', requires={'ctx'})
 def shownode(context, mapping):
     """String. The changeset identification hash, as a 40 hexadecimal
     digit string.
     """
     ctx = context.resource(mapping, 'ctx')
     return ctx.hex()
 
 @templatekeyword('obsolete', requires={'ctx'})
 def showobsolete(context, mapping):
     """String. Whether the changeset is obsolete. (EXPERIMENTAL)"""
     ctx = context.resource(mapping, 'ctx')
     if ctx.obsolete():
         return 'obsolete'
     return ''
 
 @templatekeyword('peerurls', requires={'repo'})
 def showpeerurls(context, mapping):
     """A dictionary of repository locations defined in the [paths] section
     of your configuration file."""
     repo = context.resource(mapping, 'repo')
     # see commands.paths() for naming of dictionary keys
     paths = repo.ui.paths
     urls = util.sortdict((k, p.rawloc) for k, p in sorted(paths.iteritems()))
     def makemap(k):
         p = paths[k]
         d = {'name': k, 'url': p.rawloc}
         d.update((o, v) for o, v in sorted(p.suboptions.iteritems()))
         return d
     return _hybrid(None, urls, makemap, lambda k: '%s=%s' % (k, urls[k]))
 
 @templatekeyword("predecessors", requires={'repo', 'ctx'})
 def showpredecessors(context, mapping):
     """Returns the list if the closest visible successors. (EXPERIMENTAL)"""
     repo = context.resource(mapping, 'repo')
     ctx = context.resource(mapping, 'ctx')
     predecessors = sorted(obsutil.closestpredecessors(repo, ctx.node()))
     predecessors = map(hex, predecessors)
 
     return _hybrid(None, predecessors,
                    lambda x: {'ctx': repo[x], 'revcache': {}},
                    lambda x: scmutil.formatchangeid(repo[x]))
 
 @templatekeyword('reporoot', requires={'repo'})
 def showreporoot(context, mapping):
     """String. The root directory of the current repository."""
     repo = context.resource(mapping, 'repo')
     return repo.root
 
 @templatekeyword("successorssets", requires={'repo', 'ctx'})
 def showsuccessorssets(context, mapping):
     """Returns a string of sets of successors for a changectx. Format used
     is: [ctx1, ctx2], [ctx3] if ctx has been splitted into ctx1 and ctx2
     while also diverged into ctx3. (EXPERIMENTAL)"""
     repo = context.resource(mapping, 'repo')
     ctx = context.resource(mapping, 'ctx')
     if not ctx.obsolete():
         return ''
 
     ssets = obsutil.successorssets(repo, ctx.node(), closest=True)
     ssets = [[hex(n) for n in ss] for ss in ssets]
 
     data = []
     for ss in ssets:
         h = _hybrid(None, ss, lambda x: {'ctx': repo[x], 'revcache': {}},
                     lambda x: scmutil.formatchangeid(repo[x]))
         data.append(h)
 
     # Format the successorssets
     def render(d):
         t = []
         for i in d.gen():
             t.append(i)
         return "".join(t)
 
     def gen(data):
         yield "; ".join(render(d) for d in data)
 
     return _hybrid(gen(data), data, lambda x: {'successorset': x},
                    pycompat.identity)
 
 @templatekeyword("succsandmarkers", requires={'repo', 'ctx', 'templ'})
 def showsuccsandmarkers(context, mapping):
     """Returns a list of dict for each final successor of ctx. The dict
     contains successors node id in "successors" keys and the list of
     obs-markers from ctx to the set of successors in "markers".
     (EXPERIMENTAL)
     """
     repo = context.resource(mapping, 'repo')
     ctx = context.resource(mapping, 'ctx')
     templ = context.resource(mapping, 'templ')
 
     values = obsutil.successorsandmarkers(repo, ctx)
 
     if values is None:
         values = []
 
     # Format successors and markers to avoid exposing binary to templates
     data = []
     for i in values:
         # Format successors
         successors = i['successors']
 
         successors = [hex(n) for n in successors]
         successors = _hybrid(None, successors,
                              lambda x: {'ctx': repo[x], 'revcache': {}},
                              lambda x: scmutil.formatchangeid(repo[x]))
 
         # Format markers
         finalmarkers = []
         for m in i['markers']:
             hexprec = hex(m[0])
             hexsucs = tuple(hex(n) for n in m[1])
             hexparents = None
             if m[5] is not None:
                 hexparents = tuple(hex(n) for n in m[5])
             newmarker = (hexprec, hexsucs) + m[2:5] + (hexparents,) + m[6:]
             finalmarkers.append(newmarker)
 
         data.append({'successors': successors, 'markers': finalmarkers})
 
     f = _showlist('succsandmarkers', data, templ, mapping)
     return _hybrid(f, data, lambda x: x, pycompat.identity)
 
 @templatekeyword('p1rev', requires={'ctx'})
 def showp1rev(context, mapping):
     """Integer. The repository-local revision number of the changeset's
     first parent, or -1 if the changeset has no parents."""
     ctx = context.resource(mapping, 'ctx')
     return ctx.p1().rev()
 
 @templatekeyword('p2rev', requires={'ctx'})
 def showp2rev(context, mapping):
     """Integer. The repository-local revision number of the changeset's
     second parent, or -1 if the changeset has no second parent."""
     ctx = context.resource(mapping, 'ctx')
     return ctx.p2().rev()
 
 @templatekeyword('p1node', requires={'ctx'})
 def showp1node(context, mapping):
     """String. The identification hash of the changeset's first parent,
     as a 40 digit hexadecimal string. If the changeset has no parents, all
     digits are 0."""
     ctx = context.resource(mapping, 'ctx')
     return ctx.p1().hex()
 
 @templatekeyword('p2node', requires={'ctx'})
 def showp2node(context, mapping):
     """String. The identification hash of the changeset's second
     parent, as a 40 digit hexadecimal string. If the changeset has no second
     parent, all digits are 0."""
     ctx = context.resource(mapping, 'ctx')
     return ctx.p2().hex()
 
 @templatekeyword('parents', requires={'repo', 'ctx', 'templ'})
 def showparents(context, mapping):
     """List of strings. The parents of the changeset in "rev:node"
     format. If the changeset has only one "natural" parent (the predecessor
     revision) nothing is shown."""
     repo = context.resource(mapping, 'repo')
     ctx = context.resource(mapping, 'ctx')
     templ = context.resource(mapping, 'templ')
     pctxs = scmutil.meaningfulparents(repo, ctx)
     prevs = [p.rev() for p in pctxs]
     parents = [[('rev', p.rev()),
                 ('node', p.hex()),
                 ('phase', p.phasestr())]
                for p in pctxs]
     f = _showlist('parent', parents, templ, mapping)
     return _hybrid(f, prevs, lambda x: {'ctx': repo[x], 'revcache': {}},
                    lambda x: scmutil.formatchangeid(repo[x]), keytype=int)
 
 @templatekeyword('phase', requires={'ctx'})
 def showphase(context, mapping):
     """String. The changeset phase name."""
     ctx = context.resource(mapping, 'ctx')
     return ctx.phasestr()
 
 @templatekeyword('phaseidx', requires={'ctx'})
 def showphaseidx(context, mapping):
     """Integer. The changeset phase index. (ADVANCED)"""
     ctx = context.resource(mapping, 'ctx')
     return ctx.phase()
 
 @templatekeyword('rev', requires={'ctx'})
 def showrev(context, mapping):
     """Integer. The repository-local changeset revision number."""
     ctx = context.resource(mapping, 'ctx')
     return scmutil.intrev(ctx)
 
 def showrevslist(context, mapping, name, revs):
     """helper to generate a list of revisions in which a mapped template will
     be evaluated"""
     repo = context.resource(mapping, 'repo')
     templ = context.resource(mapping, 'templ')
     f = _showlist(name, ['%d' % r for r in revs], templ, mapping)
     return _hybrid(f, revs,
                    lambda x: {name: x, 'ctx': repo[x], 'revcache': {}},
                    pycompat.identity, keytype=int)
 
 @templatekeyword('subrepos', requires={'ctx', 'templ'})
 def showsubrepos(context, mapping):
     """List of strings. Updated subrepositories in the changeset."""
     ctx = context.resource(mapping, 'ctx')
     substate = ctx.substate
     if not substate:
         return compatlist(context, mapping, 'subrepo', [])
     psubstate = ctx.parents()[0].substate or {}
     subrepos = []
     for sub in substate:
         if sub not in psubstate or substate[sub] != psubstate[sub]:
             subrepos.append(sub) # modified or newly added in ctx
     for sub in psubstate:
         if sub not in substate:
             subrepos.append(sub) # removed in ctx
     return compatlist(context, mapping, 'subrepo', sorted(subrepos))
 
 # don't remove "showtags" definition, even though namespaces will put
 # a helper function for "tags" keyword into "keywords" map automatically,
 # because online help text is built without namespaces initialization
 @templatekeyword('tags', requires={'repo', 'ctx', 'templ'})
 def showtags(context, mapping):
     """List of strings. Any tags associated with the changeset."""
     return shownames(context, mapping, 'tags')
 
 @templatekeyword('termwidth', requires={'ui'})
 def showtermwidth(context, mapping):
     """Integer. The width of the current terminal."""
     ui = context.resource(mapping, 'ui')
     return ui.termwidth()
 
 @templatekeyword('instabilities', requires={'ctx', 'templ'})
 def showinstabilities(context, mapping):
     """List of strings. Evolution instabilities affecting the changeset.
     (EXPERIMENTAL)
     """
     ctx = context.resource(mapping, 'ctx')
     return compatlist(context, mapping, 'instability', ctx.instabilities(),
                       plural='instabilities')
 
 @templatekeyword('verbosity', requires={'ui'})
 def showverbosity(context, mapping):
     """String. The current output verbosity in 'debug', 'quiet', 'verbose',
     or ''."""
     ui = context.resource(mapping, 'ui')
     # see logcmdutil.changesettemplater for priority of these flags
     if ui.debugflag:
         return 'debug'
     elif ui.quiet:
         return 'quiet'
     elif ui.verbose:
         return 'verbose'
     return ''
 
 def loadkeyword(ui, extname, registrarobj):
     """Load template keyword from specified registrarobj
     """
     for name, func in registrarobj._table.iteritems():
         keywords[name] = func
 
 # tell hggettext to extract docstrings from these functions:
 i18nfunctions = keywords.values()