formatter: add nullformatter

This can be used as a placeholder variable.

mercurial/formatter.py

@@ -1,461 +1,465
 # 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.fout = sys.stdout  # redirect to doctest
 ...     ui.verbose = verbose
 ...     return fn(ui, ui.formatter(fn.__name__, opts))
 
 Basic example:
 
 >>> def files(ui, fm):
 ...     files = [('foo', 123, (0, 0)), ('bar', 456, (1, 0))]
 ...     for f in files:
 ...         fm.startitem()
 ...         fm.write('path', '%s', f[0])
 ...         fm.condwrite(ui.verbose, 'date', '  %s',
 ...                      fm.formatdate(f[2], '%Y-%m-%d %H:%M:%S'))
 ...         fm.data(size=f[1])
 ...         fm.plain('\\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='json')
 [
  {
   "date": [0, 0],
   "path": "foo",
   "size": 123
  },
  {
   "date": [1, 0],
   "path": "bar",
   "size": 456
  }
 ]
 >>> show(files, template='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('repo', '[%s]\\n', 'baz')
 ...     files(ui, fm.nested('files'))
 ...     fm.end()
 >>> show(subrepos)
 [baz]
 foo
 bar
 >>> show(subrepos, template='{repo}: {join(files % "{path}", ", ")}\\n')
 baz: foo, bar
 """
 
 from __future__ import absolute_import
 
 import contextlib
 import itertools
 import os
 
 from .i18n import _
 from .node import (
     hex,
     short,
 )
 
 from . import (
     error,
     pycompat,
     templatefilters,
     templatekw,
     templater,
     util,
 )
 
 pickle = util.pickle
 
 class _nullconverter(object):
     '''convert non-primitive data types to be processed by formatter'''
     @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'''
         pass
     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=' '):
         '''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=' '):
         '''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'''
         pass
     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'''
         pass
     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'''
     @staticmethod
     def formatdate(date, fmt):
         '''stringify date tuple in the given format'''
         return util.datestr(date, fmt)
     @staticmethod
     def formatdict(data, key, value, fmt, sep):
         '''stringify key-value pairs separated by sep'''
         return sep.join(fmt % (k, v) for k, v in _iteritems(data))
     @staticmethod
     def formatlist(data, name, fmt, sep):
         '''stringify iterable separated by sep'''
         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("    " + repr(self._item) + ",\n")
     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'''
     @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
         self._topic = topic
         self._t = gettemplater(ui, topic, opts.get('template', ''),
                                cache=templatekw.defaulttempl)
         self._counter = itertools.count()
         self._cache = {}  # for templatekw/funcs to store reusable data
     def context(self, **ctxs):
         '''insert context objects to be used to render template keywords'''
         assert all(k == 'ctx' for k in ctxs)
         self._item.update(ctxs)
     def _showitem(self):
         # TODO: add support for filectx. probably each template keyword or
         # function will have to declare dependent resources. e.g.
         # @templatekeyword(..., requires=('ctx',))
         props = {}
         if 'ctx' in self._item:
             props.update(templatekw.keywords)
         props['index'] = next(self._counter)
         # explicitly-defined fields precede templatekw
         props.update(self._item)
         if 'ctx' in self._item:
             # but template resources must be always available
             props['templ'] = self._t
             props['repo'] = props['ctx'].repo()
             props['revcache'] = {}
         g = self._t(self._topic, ui=self._ui, cache=self._cache, **props)
         self._out.write(templater.stringify(g))
 
 def lookuptemplate(ui, topic, tmpl):
     # looks like a literal template?
     if '{' in tmpl:
         return 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 None, mapname
 
     # perhaps it's a reference to [templates]
     t = ui.config('templates', tmpl)
     if t:
         return templater.unquotestring(t), 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 None, os.path.realpath(tmpl)
         tmpl = open(tmpl).read()
         return tmpl, None
 
     # constant string?
     return tmpl, None
 
 def gettemplater(ui, topic, spec, cache=None):
     tmpl, mapfile = lookuptemplate(ui, topic, spec)
     assert not (tmpl and mapfile)
     if mapfile:
         return templater.templater.frommapfile(mapfile, cache=cache)
     return maketemplater(ui, topic, tmpl, cache=cache)
 
 def maketemplater(ui, topic, tmpl, cache=None):
     """Create a templater from a string template 'tmpl'"""
     aliases = ui.configitems('templatealias')
     t = templater.templater(cache=cache, aliases=aliases)
     if tmpl:
         t.cache[topic] = tmpl
     return t
 
 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)