1 # Copyright (C) 2010 W. Trevor King <wking@drexel.edu>
3 # This file is part of Hooke.
5 # Hooke is free software: you can redistribute it and/or
6 # modify it under the terms of the GNU Lesser General Public
7 # License as published by the Free Software Foundation, either
8 # version 3 of the License, or (at your option) any later version.
10 # Hooke is distributed in the hope that it will be useful,
11 # but WITHOUT ANY WARRANTY; without even the implied warranty of
12 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 # GNU Lesser General Public License for more details.
15 # You should have received a copy of the GNU Lesser General Public
16 # License along with Hooke. If not, see
17 # <http://www.gnu.org/licenses/>.
19 """The `command` module provides :class:`Command`\s and
20 :class:`Argument`\s for defining commands.
22 It also provides :class:`CommandExit` and subclasses for communicating
23 command completion information between
24 :class:`hooke.engine.CommandEngine`\s and
25 :class:`hooke.ui.UserInterface`\s.
34 class CommandExit (Exception):
37 class Success (CommandExit):
41 """The command requests an end to the interpreter session.
45 class Failure (CommandExit):
48 class UncaughtException (Failure):
49 def __init__(self, exception, traceback_string=None):
50 super(UncaughtException, self).__init__()
51 if traceback_string == None:
52 traceback_string = traceback.format_exc()
54 self.exception = exception
55 self.traceback = traceback_string
56 self.__setstate__(self.__getstate__())
58 def __getstate__(self):
59 """Return a picklable representation of the objects state.
61 :mod:`pickle`'s doesn't call a :meth:`__init__` when
62 rebuilding a class instance. To preserve :attr:`args` through
63 a pickle cycle, we use :meth:`__getstate__` and
66 See `pickling class instances`_ and `pickling examples`_.
68 .. _pickling class instances:
69 http://docs.python.org/library/pickle.html#pickling-and-unpickling-normal-class-instances
70 .. _pickling examples:
71 http://docs.python.org/library/pickle.html#example
73 return {'exception':self.exception, 'traceback':self.traceback}
75 def __setstate__(self, state):
76 """Apply the picklable state from :meth:`__getstate__` to
77 reconstruct the instance.
79 for key,value in state.items():
80 setattr(self, key, value)
81 self.args = (self.traceback + str(self.exception),)
84 class Command (object):
85 """One-line command description here.
87 >>> c = Command(name='test', help='An example Command.')
89 >>> status = c.run(hooke, NullQueue(), PrintQueue(),
90 ... help=True) # doctest: +REPORT_UDIFF
96 help BOOL (bool) Print a help message.
102 def __init__(self, name, aliases=None, arguments=[], help=''):
103 # TODO: see_also=[other,command,instances,...]
107 self.aliases = aliases
109 Argument(name='help', type='bool', default=False, count=1,
110 help='Print a help message.'),
114 def run(self, hooke, inqueue=None, outqueue=None, **kwargs):
115 """`Normalize inputs and handle <Argument help> before punting
119 inqueue = NullQueue()
121 outqueue = NullQueue()
123 params = self.handle_arguments(hooke, inqueue, outqueue, kwargs)
124 if params['help'] == True:
125 outqueue.put(self.help())
127 self._run(hooke, inqueue, outqueue, params)
128 except CommandExit, e:
129 if isinstance(e, Failure):
132 # other CommandExit subclasses fall through to the end
134 x = UncaughtException(e)
142 def _run(self, inqueue, outqueue, params):
143 """This is where the command-specific magic will happen.
147 def handle_arguments(self, hooke, inqueue, outqueue, params):
148 """Normalize and validate input parameters (:class:`Argument` values).
150 for argument in self.arguments:
151 names = [argument.name] + argument.aliases
152 settings = [(name,v) for name,v in params.items() if name in names]
153 num_provided = len(settings)
154 if num_provided == 0:
155 if argument.optional == True or argument.count == 0:
156 settings = [(argument.name, argument.default)]
158 raise Failure('Required argument %s not set.'
161 raise Failure('Multiple settings for %s:\n %s'
163 '\n '.join(['%s: %s' % (name,value)
164 for name,value in sorted(settings)])))
165 name,value = settings[0]
166 if num_provided == 0:
167 params[argument.name] = value
169 if name != argument.name:
171 params[argument.name] = value
172 if argument.callback != None:
173 value = argument.callback(hooke, self, argument, value)
174 params[argument.name] = value
175 argument.validate(value)
178 def help(self, name_fn=lambda name:name):
179 """Return a help message describing the `Command`.
181 `name_fn(internal_name) -> external_name` gives calling
182 :class:`hooke.ui.UserInterface`\s a means of changing the
183 display names if it wants (e.g. to remove spaces from command
186 name_part = 'Command: %s' % name_fn(self.name)
187 if len(self.aliases) > 0:
188 name_part += ' (%s)' % ', '.join(
189 [name_fn(n) for n in self.aliases])
191 if len(self.arguments) > 0:
192 argument_part = ['Arguments:', '']
193 for a in self.arguments:
194 argument_part.append(textwrap.fill(
197 subsequent_indent=" "))
198 argument_part = '\n'.join(argument_part)
199 parts.append(argument_part)
200 parts.append(self._help) # help part
201 return '\n\n'.join(parts)
203 class Argument (object):
204 """Structured user input for :class:`Command`\s.
206 TODO: ranges for `count`?
208 def __init__(self, name, aliases=None, type='string', metavar=None,
209 default=None, optional=True, count=1,
210 completion_callback=None, callback=None, help=''):
214 self.aliases = aliases
217 metavar = type.upper()
218 self.metavar = metavar
219 self.default = default
220 self.optional = optional
222 self.completion_callback = completion_callback
223 self.callback = callback
227 return '<%s %s>' % (self.__class__.__name__, self.name)
230 return self.__str__()
232 def help(self, name_fn=lambda name:name):
233 """Return a help message describing the `Argument`.
235 `name_fn(internal_name) -> external_name` gives calling
236 :class:`hooke.ui.UserInterface`\s a means of changing the
237 display names if it wants (e.g. to remove spaces from command
240 parts = ['%s ' % name_fn(self.name)]
241 if self.metavar != None:
242 parts.append('%s ' % self.metavar)
243 parts.extend(['(%s) ' % self.type, self._help])
244 return ''.join(parts)
246 def validate(self, value):
247 """If `value` is not appropriate, raise `ValueError`.
249 pass # TODO: validation
251 # TODO: type conversion
253 # TODO: type extensions?
257 class StoreValue (object):
258 def __init__(self, value):
260 def __call__(self, hooke, command, argument, fragment=None):
263 class NullQueue (queue.Queue):
264 """The :class:`queue.Queue` equivalent of `/dev/null`.
266 This is a bottomless pit. Items go in, but never come out.
268 def get(self, block=True, timeout=None):
269 """Raise queue.Empty.
271 There's really no need to override the base Queue.get, but I
272 want to know if someone tries to read from a NullQueue. With
273 the default implementation they would just block silently
278 def put(self, item, block=True, timeout=None):
279 """Dump an item into the void.
281 Block and timeout are meaningless, because there is always a
282 free slot available in a bottomless pit.
286 class PrintQueue (NullQueue):
287 """Debugging :class:`NullQueue` that prints items before dropping
290 def put(self, item, block=True, timeout=None):
291 """Print `item` and then dump it into the void.
293 print 'ITEM:\n%s' % item