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fancy_getopt.py
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"""distutils.fancy_getopt Wrapper around the standard getopt module that provides the following additional features: * short and long options are tied together * options have help strings, so fancy_getopt could potentially create a complete usage summary * options set attributes of a passed-in object """ import sys import string import re import getopt from .errors import DistutilsGetoptError, DistutilsArgError # Much like command_re in distutils.core, this is close to but not quite # the same as a Python NAME -- except, in the spirit of most GNU # utilities, we use '-' in place of '_'. (The spirit of LISP lives on!) # The similarities to NAME are again not a coincidence... longopt_pat = r'[a-zA-Z](?:[a-zA-Z0-9-]*)' longopt_re = re.compile(r'^%s$' % longopt_pat) # For recognizing "negative alias" options, eg. "quiet=!verbose" neg_alias_re = re.compile("^({})=!({})$".format(longopt_pat, longopt_pat)) # This is used to translate long options to legitimate Python identifiers # (for use as attributes of some object). longopt_xlate = str.maketrans('-', '_') class FancyGetopt: """Wrapper around the standard 'getopt()' module that provides some handy extra functionality: * short and long options are tied together * options have help strings, and help text can be assembled from them * options set attributes of a passed-in object * boolean options can have "negative aliases" -- eg. if --quiet is the "negative alias" of --verbose, then "--quiet" on the command line sets 'verbose' to false """ def __init__(self, option_table=None): # The option table is (currently) a list of tuples. The # tuples may have 3 or four values: # (long_option, short_option, help_string [, repeatable]) # if an option takes an argument, its long_option should have '=' # appended; short_option should just be a single character, no ':' # in any case. If a long_option doesn't have a corresponding # short_option, short_option should be None. All option tuples # must have long options. self.option_table = option_table # 'option_index' maps long option names to entries in the option # table (ie. those 3-tuples). self.option_index = {} if self.option_table: self._build_index() # 'alias' records (duh) alias options; {'foo': 'bar'} means # --foo is an alias for --bar self.alias = {} # 'negative_alias' keeps track of options that are the boolean # opposite of some other option self.negative_alias = {} # These keep track of the information in the option table. We # don't actually populate these structures until we're ready to # parse the command-line, since the 'option_table' passed in here # isn't necessarily the final word. self.short_opts = [] self.long_opts = [] self.short2long = {} self.attr_name = {} self.takes_arg = {} # And 'option_order' is filled up in 'getopt()'; it records the # original order of options (and their values) on the command-line, # but expands short options, converts aliases, etc. self.option_order = [] def _build_index(self): self.option_index.clear() for option in self.option_table: self.option_index[option[0]] = option def set_option_table(self, option_table): self.option_table = option_table self._build_index() def add_option(self, long_option, short_option=None, help_string=None): if long_option in self.option_index: raise DistutilsGetoptError( "option conflict: already an option '%s'" % long_option ) else: option = (long_option, short_option, help_string) self.option_table.append(option) self.option_index[long_option] = option def has_option(self, long_option): """Return true if the option table for this parser has an option with long name 'long_option'.""" return long_option in self.option_index def get_attr_name(self, long_option): """Translate long option name 'long_option' to the form it has as an attribute of some object: ie., translate hyphens to underscores.""" return long_option.translate(longopt_xlate) def _check_alias_dict(self, aliases, what): assert isinstance(aliases, dict) for (alias, opt) in aliases.items(): if alias not in self.option_index: raise DistutilsGetoptError( ("invalid %s '%s': " "option '%s' not defined") % (what, alias, alias) ) if opt not in self.option_index: raise DistutilsGetoptError( ("invalid %s '%s': " "aliased option '%s' not defined") % (what, alias, opt) ) def set_aliases(self, alias): """Set the aliases for this option parser.""" self._check_alias_dict(alias, "alias") self.alias = alias def set_negative_aliases(self, negative_alias): """Set the negative aliases for this option parser. 'negative_alias' should be a dictionary mapping option names to option names, both the key and value must already be defined in the option table.""" self._check_alias_dict(negative_alias, "negative alias") self.negative_alias = negative_alias def _grok_option_table(self): # noqa: C901 """Populate the various data structures that keep tabs on the option table. Called by 'getopt()' before it can do anything worthwhile. """ self.long_opts = [] self.short_opts = [] self.short2long.clear() self.repeat = {} for option in self.option_table: if len(option) == 3: long, short, help = option repeat = 0 elif len(option) == 4: long, short, help, repeat = option else: # the option table is part of the code, so simply # assert that it is correct raise ValueError("invalid option tuple: {!r}".format(option)) # Type- and value-check the option names if not isinstance(long, str) or len(long) < 2: raise DistutilsGetoptError( ("invalid long option '%s': " "must be a string of length >= 2") % long ) if not ((short is None) or (isinstance(short, str) and len(short) == 1)): raise DistutilsGetoptError( "invalid short option '%s': " "must a single character or None" % short ) self.repeat[long] = repeat self.long_opts.append(long) if long[-1] == '=': # option takes an argument? if short: short = short + ':' long = long[0:-1] self.takes_arg[long] = 1 else: # Is option is a "negative alias" for some other option (eg. # "quiet" == "!verbose")? alias_to = self.negative_alias.get(long) if alias_to is not None: if self.takes_arg[alias_to]: raise DistutilsGetoptError( "invalid negative alias '%s': " "aliased option '%s' takes a value" % (long, alias_to) ) self.long_opts[-1] = long # XXX redundant?! self.takes_arg[long] = 0 # If this is an alias option, make sure its "takes arg" flag is # the same as the option it's aliased to. alias_to = self.alias.get(long) if alias_to is not None: if self.takes_arg[long] != self.takes_arg[alias_to]: raise DistutilsGetoptError( "invalid alias '%s': inconsistent with " "aliased option '%s' (one of them takes a value, " "the other doesn't" % (long, alias_to) ) # Now enforce some bondage on the long option name, so we can # later translate it to an attribute name on some object. Have # to do this a bit late to make sure we've removed any trailing # '='. if not longopt_re.match(long): raise DistutilsGetoptError( "invalid long option name '%s' " "(must be letters, numbers, hyphens only" % long ) self.attr_name[long] = self.get_attr_name(long) if short: self.short_opts.append(short) self.short2long[short[0]] = long def getopt(self, args=None, object=None): # noqa: C901 """Parse command-line options in args. Store as attributes on object. If 'args' is None or not supplied, uses 'sys.argv[1:]'. If 'object' is None or not supplied, creates a new OptionDummy object, stores option values there, and returns a tuple (args, object). If 'object' is supplied, it is modified in place and 'getopt()' just returns 'args'; in both cases, the returned 'args' is a modified copy of the passed-in 'args' list, which is left untouched. """ if args is None: args = sys.argv[1:] if object is None: object = OptionDummy() created_object = True else: created_object = False self._grok_option_table() short_opts = ' '.join(self.short_opts) try: opts, args = getopt.getopt(args, short_opts, self.long_opts) except getopt.error as msg: raise DistutilsArgError(msg) for opt, val in opts: if len(opt) == 2 and opt[0] == '-': # it's a short option opt = self.short2long[opt[1]] else: assert len(opt) > 2 and opt[:2] == '--' opt = opt[2:] alias = self.alias.get(opt) if alias: opt = alias if not self.takes_arg[opt]: # boolean option? assert val == '', "boolean option can't have value" alias = self.negative_alias.get(opt) if alias: opt = alias val = 0 else: val = 1 attr = self.attr_name[opt] # The only repeating option at the moment is 'verbose'. # It has a negative option -q quiet, which should set verbose = 0. if val and self.repeat.get(attr) is not None: val = getattr(object, attr, 0) + 1 setattr(object, attr, val) self.option_order.append((opt, val)) # for opts if created_object: return args, object else: return args def get_option_order(self): """Returns the list of (option, value) tuples processed by the previous run of 'getopt()'. Raises RuntimeError if 'getopt()' hasn't been called yet. """ if self.option_order is None: raise RuntimeError("'getopt()' hasn't been called yet") else: return self.option_order def generate_help(self, header=None): # noqa: C901 """Generate help text (a list of strings, one per suggested line of output) from the option table for this FancyGetopt object. """ # Blithely assume the option table is good: probably wouldn't call # 'generate_help()' unless you've already called 'getopt()'. # First pass: determine maximum length of long option names max_opt = 0 for option in self.option_table: long = option[0] short = option[1] ell = len(long) if long[-1] == '=': ell = ell - 1 if short is not None: ell = ell + 5 # " (-x)" where short == 'x' if ell > max_opt: max_opt = ell opt_width = max_opt + 2 + 2 + 2 # room for indent + dashes + gutter # Typical help block looks like this: # --foo controls foonabulation # Help block for longest option looks like this: # --flimflam set the flim-flam level # and with wrapped text: # --flimflam set the flim-flam level (must be between # 0 and 100, except on Tuesdays) # Options with short names will have the short name shown (but # it doesn't contribute to max_opt): # --foo (-f) controls foonabulation # If adding the short option would make the left column too wide, # we push the explanation off to the next line # --flimflam (-l) # set the flim-flam level # Important parameters: # - 2 spaces before option block start lines # - 2 dashes for each long option name # - min. 2 spaces between option and explanation (gutter) # - 5 characters (incl. space) for short option name # Now generate lines of help text. (If 80 columns were good enough # for Jesus, then 78 columns are good enough for me!) line_width = 78 text_width = line_width - opt_width big_indent = ' ' * opt_width if header: lines = [header] else: lines = ['Option summary:'] for option in self.option_table: long, short, help = option[:3] text = wrap_text(help, text_width) if long[-1] == '=': long = long[0:-1] # Case 1: no short option at all (makes life easy) if short is None: if text: lines.append(" --%-*s %s" % (max_opt, long, text[0])) else: lines.append(" --%-*s " % (max_opt, long)) # Case 2: we have a short option, so we have to include it # just after the long option else: opt_names = "{} (-{})".format(long, short) if text: lines.append(" --%-*s %s" % (max_opt, opt_names, text[0])) else: lines.append(" --%-*s" % opt_names) for ell in text[1:]: lines.append(big_indent + ell) return lines def print_help(self, header=None, file=None): if file is None: file = sys.stdout for line in self.generate_help(header): file.write(line + "\n") def fancy_getopt(options, negative_opt, object, args): parser = FancyGetopt(options) parser.set_negative_aliases(negative_opt) return parser.getopt(args, object) WS_TRANS = {ord(_wschar): ' ' for _wschar in string.whitespace} def wrap_text(text, width): """wrap_text(text : string, width : int) -> [string] Split 'text' into multiple lines of no more than 'width' characters each, and return the list of strings that results. """ if text is None: return [] if len(text) <= width: return [text] text = text.expandtabs() text = text.translate(WS_TRANS) chunks = re.split(r'( +|-+)', text) chunks = [ch for ch in chunks if ch] # ' - ' results in empty strings lines = [] while chunks: cur_line = [] # list of chunks (to-be-joined) cur_len = 0 # length of current line while chunks: ell = len(chunks[0]) if cur_len + ell <= width: # can squeeze (at least) this chunk in cur_line.append(chunks[0]) del chunks[0] cur_len = cur_len + ell else: # this line is full # drop last chunk if all space if cur_line and cur_line[-1][0] == ' ': del cur_line[-1] break if chunks: # any chunks left to process? # if the current line is still empty, then we had a single # chunk that's too big too fit on a line -- so we break # down and break it up at the line width if cur_len == 0: cur_line.append(chunks[0][0:width]) chunks[0] = chunks[0][width:] # all-whitespace chunks at the end of a line can be discarded # (and we know from the re.split above that if a chunk has # *any* whitespace, it is *all* whitespace) if chunks[0][0] == ' ': del chunks[0] # and store this line in the list-of-all-lines -- as a single # string, of course! lines.append(''.join(cur_line)) return lines def translate_longopt(opt): """Convert a long option name to a valid Python identifier by changing "-" to "_". """ return opt.translate(longopt_xlate) class OptionDummy: """Dummy class just used as a place to hold command-line option values as instance attributes.""" def __init__(self, options=[]): """Create a new OptionDummy instance. The attributes listed in 'options' will be initialized to None.""" for opt in options: setattr(self, opt, None) if __name__ == "__main__": text = """\ Tra-la-la, supercalifragilisticexpialidocious. How *do* you spell that odd word, anyways? (Someone ask Mary -- she'll know [or she'll say, "How should I know?"].)""" for w in (10, 20, 30, 40): print("width: %d" % w) print("\n".join(wrap_text(text, w))) print()