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1import os
2import sys
3import array
4import textwrap
6from boltons.iterutils import unique, split
8from face.utils import format_flag_label, format_flag_post_doc, format_posargs_label, echo
9from face.parser import Flag
11DEFAULT_HELP_FLAG = Flag('--help', parse_as=True, char='-h', doc='show this help message and exit')
12DEFAULT_MAX_WIDTH = 120
15def _get_termios_winsize():
16 # TLPI, 62.9 (p. 1319)
17 import fcntl
18 import termios
20 winsize = array.array('H', [0, 0, 0, 0])
22 assert not fcntl.ioctl(sys.stdout, termios.TIOCGWINSZ, winsize)
24 ws_row, ws_col, _, _ = winsize
26 return ws_row, ws_col
29def _get_environ_winsize():
30 # the argparse approach. not sure which systems this works or
31 # worked on, if any. ROWS/COLUMNS are special shell variables.
32 try:
33 rows, columns = int(os.environ['ROWS']), int(os.environ['COLUMNS'])
34 except (KeyError, ValueError):
35 rows, columns = None, None
36 return rows, columns
39def get_winsize():
40 rows, cols = None, None
41 try:
42 rows, cols = _get_termios_winsize()
43 except Exception:
44 try:
45 rows, cols = _get_environ_winsize()
46 except Exception:
47 pass
48 return rows, cols
51def get_wrap_width(max_width=DEFAULT_MAX_WIDTH):
52 _, width = get_winsize()
53 if width is None:
54 width = 80
55 width = min(width, max_width)
56 width -= 2
57 return width
60def _wrap_stout_pair(indent, label, sep, doc, doc_start, max_doc_width):
61 # TODO: consider making the fill character configurable (ljust
62 # uses space by default, the just() methods can only take
63 # characters, might be a useful bolton to take a repeating
64 # sequence)
65 ret = []
66 append = ret.append
67 lhs = indent + label
69 if not doc:
70 append(lhs)
71 return ret
73 len_sep = len(sep)
74 wrapped_doc = textwrap.wrap(doc, max_doc_width)
75 if len(lhs) <= doc_start:
76 lhs_f = lhs.ljust(doc_start - len(sep)) + sep
77 append(lhs_f + wrapped_doc[0])
78 else:
79 append(lhs)
80 append((' ' * (doc_start - len_sep)) + sep + wrapped_doc[0])
82 for line in wrapped_doc[1:]:
83 append(' ' * doc_start + line)
85 return ret
88def _wrap_stout_cmd_doc(indent, doc, max_width):
89 """Function for wrapping command description."""
90 parts = []
91 paras = ['\n'.join(para) for para in
92 split(doc.splitlines(), lambda l: not l.lstrip())
93 if para]
94 for para in paras:
95 part = textwrap.fill(text=para,
96 width=(max_width - len(indent)),
97 initial_indent=indent,
98 subsequent_indent=indent)
99 parts.append(part)
100 return '\n\n'.join(parts)
103def get_stout_layout(labels, indent, sep, width=None, max_width=DEFAULT_MAX_WIDTH,
104 min_doc_width=40):
105 width = width or get_wrap_width(max_width=max_width)
107 len_sep = len(sep)
108 len_indent = len(indent)
110 max_label_width = 0
111 max_doc_width = min_doc_width
112 doc_start = width - min_doc_width
113 for label in labels:
114 cur_len = len(label)
115 if cur_len < max_label_width:
116 continue
117 max_label_width = cur_len
118 if (len_indent + cur_len + len_sep + min_doc_width) < width:
119 max_doc_width = width - max_label_width - len_sep - len_indent
120 doc_start = len_indent + cur_len + len_sep
122 return {'width': width,
123 'label_width': max_label_width,
124 'doc_width': max_doc_width,
125 'doc_start': doc_start}
128DEFAULT_CONTEXT = {
129 'usage_label': 'Usage:',
130 'subcmd_section_heading': 'Subcommands: ',
131 'flags_section_heading': 'Flags: ',
132 'posargs_section_heading': 'Positional arguments:',
133 'section_break': '\n',
134 'group_break': '',
135 'subcmd_example': 'subcommand',
136 'width': None,
137 'max_width': 120,
138 'min_doc_width': 50,
139 'format_posargs_label': format_posargs_label,
140 'format_flag_label': format_flag_label,
141 'format_flag_post_doc': format_flag_post_doc,
142 'doc_separator': ' ', # ' + ' is pretty classy as bullet points, too
143 'section_indent': ' ',
144 'pre_doc': '', # TODO: these should go on CommandDisplay
145 'post_doc': '\n',
146}
149def _get_subcmd_groups(parser):
150 """Return a dict mapping group key -> list of (sub_name, subprs).
152 Group key is a string (named group), int (unnamed visual break),
153 or None (ungrouped). Insertion order preserved: first occurrence
154 of a group determines its position. None-group (ungrouped) is
155 always sorted first regardless of insertion order.
156 """
157 groups = {}
158 for sub_name in unique([sp[0] for sp in parser.subprs_map if sp]):
159 subprs = parser.subprs_map[(sub_name,)]
160 group = subprs.group
161 groups.setdefault(group, []).append((sub_name, subprs))
163 # Move ungrouped (None) to front
164 if None in groups:
165 ungrouped = groups.pop(None)
166 result = {None: ungrouped}
167 result.update(groups)
168 return result
169 return groups
172class StoutHelpFormatter:
173 """This formatter takes :class:`Parser` and :class:`Command` instances
174 and generates help text. The output style is inspired by, but not
175 the same as, argparse's automatic help formatting.
177 Probably what most Pythonists expect, this help text is slightly
178 stouter (conservative with vertical space) than other conventional
179 help messages.
181 The default output looks like::
183 Usage: example.py subcommand [FLAGS]
185 Does a bit of busy work
188 Subcommands:
190 sum Just a lil fun in the sum
191 subtract
192 print
195 Flags:
197 --help / -h show this help message and exit
198 --verbose / -V
201 Due to customizability, the constructor takes a large number of
202 keyword arguments, the most important of which are highlighted
203 here.
205 Args:
206 width (int): The width of the help output in
207 columns/characters. Defaults to the width of the terminal,
208 with a max of *max_width*.
209 max_width (int): The widest the help output will get. Too wide
210 and it can be hard to visually scan. Defaults to 120 columns.
211 min_doc_width (int): The text documentation's minimum width in
212 columns/characters. Puts flags and subcommands on their own
213 lines when they're long or the terminal is narrow. Defaults to
214 50.
215 doc_separator (str): The string to put between a
216 flag/subcommand and its documentation. Defaults to `' '`. (Try
217 `' + '` for a classy bulleted doc style.
219 An instance of StoutHelpFormatter can be passed to
220 :class:`HelpHandler`, which can in turn be passed to
221 :class:`Command` for maximum command customizability.
223 Alternatively, when using :class:`Parser` object directly, you can
224 instantiate this type and pass a :class:`Parser` object to
225 :meth:`get_help_text()` or :meth:`get_usage_line()` to get
226 identically formatted text without sacrificing flow control.
228 HelpFormatters are stateless, in that they can be used more than
229 once, with different Parsers and Commands without needing to be
230 recreated or otherwise reset.
232 """
233 default_context = dict(DEFAULT_CONTEXT)
235 def __init__(self, **kwargs):
236 self.ctx = {}
237 for key, val in self.default_context.items():
238 self.ctx[key] = kwargs.pop(key, val)
239 if kwargs:
240 raise TypeError(f'unexpected formatter arguments: {list(kwargs.keys())!r}')
242 def _get_layout(self, labels):
243 ctx = self.ctx
244 return get_stout_layout(labels=labels,
245 indent=ctx['section_indent'],
246 sep=ctx['doc_separator'],
247 width=ctx['width'],
248 max_width=ctx['max_width'],
249 min_doc_width=ctx['min_doc_width'])
251 def get_help_text(self, parser, subcmds=(), program_name=None):
252 """Turn a :class:`Parser` or :class:`Command` into a multiline
253 formatted help string, suitable for printing. Includes the
254 usage line and trailing newline by default.
256 Args:
257 parser (Parser): A :class:`Parser` or :class:`Command`
258 object to generate help text for.
259 subcmds (tuple): A sequence of subcommand strings
260 specifying the subcommand to generate help text for.
261 Defaults to ``()``.
262 program_name (str): The program name, if it differs from
263 the default ``sys.argv[0]``. (For example,
264 ``example.py``, when running the command ``python
265 example.py --flag val arg``.)
267 """
268 # TODO: incorporate "Arguments" section if posargs has a doc set
269 ctx = self.ctx
271 ret = [self.get_usage_line(parser, subcmds=subcmds, program_name=program_name)]
272 append = ret.append
273 append(ctx['group_break'])
275 shown_flags = parser.get_flags(path=subcmds, with_hidden=False)
276 if subcmds:
277 parser = parser.subprs_map[subcmds]
279 if parser.doc:
280 append(_wrap_stout_cmd_doc(indent=ctx['section_indent'],
281 doc=parser.doc,
282 max_width=ctx['width'] or get_wrap_width(
283 max_width=ctx['max_width'])))
284 append(ctx['section_break'])
286 if parser.subprs_map:
287 subcmd_groups = _get_subcmd_groups(parser)
288 has_named_groups = any(isinstance(g, str) for g in subcmd_groups)
290 # Compute layout across ALL subcommands for consistent doc-column alignment.
291 all_subcmd_names = [n.replace('_', '-') for n in
292 unique([sp[0] for sp in parser.subprs_map if sp])]
293 if has_named_groups:
294 subcmd_layout = get_stout_layout(
295 labels=all_subcmd_names,
296 indent=ctx['section_indent'] * 2,
297 sep=ctx['doc_separator'],
298 width=ctx['width'],
299 max_width=ctx['max_width'],
300 min_doc_width=ctx['min_doc_width'])
301 else:
302 subcmd_layout = self._get_layout(labels=all_subcmd_names)
304 append(ctx['subcmd_section_heading'])
305 append(ctx['group_break'])
307 first_group = True
308 for group_key, group_subcmds in subcmd_groups.items():
309 if not first_group:
310 append('') # blank line between groups
311 first_group = False
313 if isinstance(group_key, str):
314 append(ctx['section_indent'] + group_key + ':')
316 # Ungrouped items use section_indent; grouped items use double indent
317 if has_named_groups and isinstance(group_key, str):
318 item_indent = ctx['section_indent'] * 2
319 else:
320 item_indent = ctx['section_indent']
322 for sub_name, subprs in group_subcmds:
323 subcmd_lines = _wrap_stout_pair(
324 indent=item_indent,
325 label=sub_name.replace('_', '-'),
326 sep=ctx['doc_separator'],
327 doc=subprs.doc,
328 doc_start=subcmd_layout['doc_start'],
329 max_doc_width=subcmd_layout['doc_width'])
330 ret.extend(subcmd_lines)
332 append(ctx['section_break'])
334 if not shown_flags:
335 return '\n'.join(ret)
337 fmt_flag_label = ctx['format_flag_label']
338 flag_labels = [fmt_flag_label(flag) for flag in shown_flags]
339 flag_layout = self._get_layout(labels=flag_labels)
341 fmt_flag_post_doc = ctx['format_flag_post_doc']
342 append(ctx['flags_section_heading'])
343 append(ctx['group_break'])
344 for flag in shown_flags:
345 disp = flag.display
346 if disp.full_doc is not None:
347 doc = disp.full_doc
348 else:
349 _parts = [disp.doc] if disp.doc else []
350 post_doc = disp.post_doc if disp.post_doc else fmt_flag_post_doc(flag)
351 if post_doc:
352 _parts.append(post_doc)
353 doc = ' '.join(_parts)
355 flag_lines = _wrap_stout_pair(indent=ctx['section_indent'],
356 label=fmt_flag_label(flag),
357 sep=ctx['doc_separator'],
358 doc=doc,
359 doc_start=flag_layout['doc_start'],
360 max_doc_width=flag_layout['doc_width'])
362 ret.extend(flag_lines)
364 return ctx['pre_doc'] + '\n'.join(ret) + ctx['post_doc']
366 def get_usage_line(self, parser, subcmds=(), program_name=None):
367 """Get just the top line of automated text output. Arguments are the
368 same as :meth:`get_help_text()`. Basic info about running the
369 command, such as:
371 Usage: example.py subcommand [FLAGS] [args ...]
373 """
374 ctx = self.ctx
375 subcmds = tuple(subcmds or ())
376 parts = [ctx['usage_label']] if ctx['usage_label'] else []
377 append = parts.append
379 program_name = program_name or parser.name
381 append(' '.join((program_name,) + subcmds))
383 # TODO: put () in subprs_map to handle some of this sorta thing
384 if not subcmds and parser.subprs_map:
385 append('subcommand')
386 elif subcmds and parser.subprs_map[subcmds].subprs_map:
387 append('subcommand')
389 # with subcommands out of the way, look up the parser for flags and args
390 if subcmds:
391 parser = parser.subprs_map[subcmds]
393 flags = parser.get_flags(with_hidden=False)
395 if flags:
396 append('[FLAGS]')
398 if not parser.posargs.display.hidden:
399 fmt_posargs_label = ctx['format_posargs_label']
400 append(fmt_posargs_label(parser.posargs))
402 return ' '.join(parts)
406'''
407class AiryHelpFormatter(object):
408 """No wrapping a doc onto the same line as the label. Just left
409 aligned labels + newline, then right align doc. No complicated
410 width calculations either. See https://github.com/kbknapp/clap-rs
411 """
412 pass # TBI
413'''
416class HelpHandler:
417 """The HelpHandler is a one-stop object for that all-important CLI
418 feature: automatic help generation. It ties together the actual
419 help handler with the optional flag and subcommand such that it
420 can be added to any :class:`Command` instance.
422 The :class:`Command` creates a HelpHandler instance by default,
423 and its constructor also accepts an instance of this type to
424 customize a variety of helpful features.
426 Args:
427 flag (face.Flag): The Flag instance to use for triggering a
428 help output in a Command setting. Defaults to the standard
429 ``--help / -h`` flag. Pass ``False`` to disable.
430 subcmd (str): A subcommand name to be added to any
431 :class:`Command` using this HelpHandler. Defaults to
432 ``None``.
433 formatter: A help formatter instance or type. Type will be
434 instantiated with keyword arguments passed to this
435 constructor. Defaults to :class:`StoutHelpFormatter`.
436 func (callable): The actual handler function called on flag
437 presence or subcommand invocation. Defaults to
438 :meth:`HelpHandler.default_help_func()`.
440 All other remaining keyword arguments are used to construct the
441 HelpFormatter, if *formatter* is a type (as is the default). For
442 an example of a formatter, see :class:`StoutHelpFormatter`, the
443 default help formatter.
444 """
445 # Other hooks (besides the help function itself):
446 # * Callbacks for unhandled exceptions
447 # * Callbacks for formatting errors (add a "see --help for more options")
449 def __init__(self, flag=DEFAULT_HELP_FLAG, subcmd=None,
450 formatter=StoutHelpFormatter, func=None, **formatter_kwargs):
451 # subcmd expects a string
452 self.flag = flag
453 self.subcmd = subcmd
454 self.func = func if func is not None else self.default_help_func
455 if not callable(self.func):
456 raise TypeError(f'expected help handler func to be callable, not {func!r}')
458 self.formatter = formatter
459 if not formatter:
460 raise TypeError(f'expected Formatter type or instance, not: {formatter!r}')
461 if isinstance(formatter, type):
462 self.formatter = formatter(**formatter_kwargs)
463 elif formatter_kwargs:
464 raise TypeError('only accepts extra formatter kwargs (%r) if'
465 ' formatter argument is a Formatter type, not: %r'
466 % (sorted(formatter_kwargs.keys()), formatter))
467 _has_get_help_text = callable(getattr(self.formatter, 'get_help_text', None))
468 if not _has_get_help_text:
469 raise TypeError('expected valid formatter, or other object with a'
470 ' get_help_text() method, not %r' % (self.formatter,))
471 return
473 def default_help_func(self, cmd_, subcmds_, args_, command_):
474 """The default help handler function. Called when either the help flag
475 or subcommand is passed.
477 Prints the output of the help formatter instance attached to
478 this HelpHandler and exits with exit code 0.
480 """
481 echo(self.formatter.get_help_text(command_, subcmds=subcmds_, program_name=cmd_))
484"""Usage: cmd_name sub_cmd [..as many subcommands as the max] --flags args ...
486Possible commands:
488(One of the possible styles below)
490Flags:
491 Group name (if grouped):
492 -F, --flag VALUE Help text goes here. (integer, defaults to 3)
494Flag help notes:
496* don't display parenthetical if it's string/None
497* Also need to indicate required and mutual exclusion ("not with")
498* Maybe experimental / deprecated support
499* General flag listing should also include flags up the chain
501Subcommand listing styles:
503* Grouped, one-deep, flag overview on each
504* One-deep, grouped or alphabetical, help string next to each
505* Grouped by tree (new group whenever a subtree of more than one
506 member finishes), with help next to each.
508What about extra lines in the help (like zfs) (maybe each individual
509line can be a template string?)
511TODO: does face need built-in support for version subcommand/flag,
512basically identical to help?
514Group names can be ints or strings. When, group names are strings,
515flags are indented under a heading consisting of the string followed
516by a colon. All ungrouped flags go under a 'General Flags' group
517name. When group names are ints, groups are not indented, but a
518newline is still emitted by each group.
520Alphabetize should be an option, otherwise everything stays in
521insertion order.
523Subcommands without handlers should not be displayed in help. Also,
524their implicit handler prints the help.
526Subcommand groups could be Commands with name='', and they can only be
527added to other commands, where they would embed as siblings instead of
528as subcommands. Similar to how clastic subapplications can be mounted
529without necessarily adding to the path.
531Is it better to delegate representations out or keep them all within
532the help builder?
534---
536Help needs: a flag (and a way to disable it), as well as a renderer.
538Usage:
540Doc
542Subcommands:
544... ...
546Flags:
548...
550Postdoc
553{usage_label} {cmd_name} {subcmd_path} {subcmd_blank} {flags_blank} {posargs_label}
555{cmd.doc}
557{subcmd_heading}
559 {subcmd.name} {subcmd.doc} {subcmd.post_doc}
561{flags_heading}
563 {group_name}:
565 {flag_label} {flag.doc} {flag.post_doc}
567{cmd.post_doc}
570--------
572# Grouping
574Effectively sorted on: (group_name, group_index, sort_order, label)
576But group names should be based on insertion order, with the
577default-grouped/ungrouped items showing up in the last group.
579# Wrapping / Alignment
581Docs start at the position after the longest "left-hand side"
582(LHS/"key") item that would not cause the first line of the docs to be
583narrower than the minimum doc width.
585LHSes which do extend beyond this point will be on their own line,
586with the doc starting on the line below.
588# Window width considerations
590With better termios-based logic in place to get window size, there are
591going to be a lot of wider-than-80-char help messages.
593The goal of help message alignment is to help eyes track across from a
594flag or subcommand to its corresponding doc. Rather than maximizing
595width usage or topping out at a max width limit, we should be
596balancing or at least limiting the amount of whitespace between the
597shortest flag and its doc. (TODO)
599A width limit might still make sense because reading all the way
600across the screen can be tiresome, too.
602TODO: padding_top and padding_bottom attributes on various displays
603(esp FlagDisplay) to enable finer grained whitespace control without
604complicated group setups.
606"""