JezK
Edit File: string.py
"""A collection of string constants. Public module variables: whitespace -- a string containing all ASCII whitespace ascii_lowercase -- a string containing all ASCII lowercase letters ascii_uppercase -- a string containing all ASCII uppercase letters ascii_letters -- a string containing all ASCII letters digits -- a string containing all ASCII decimal digits hexdigits -- a string containing all ASCII hexadecimal digits octdigits -- a string containing all ASCII octal digits punctuation -- a string containing all ASCII punctuation characters printable -- a string containing all ASCII characters considered printable """ __all__ = ["ascii_letters", "ascii_lowercase", "ascii_uppercase", "capwords", "digits", "hexdigits", "octdigits", "printable", "punctuation", "whitespace", "Formatter", "Template"] import _string # Some strings for ctype-style character classification whitespace = ' \t\n\r\v\f' ascii_lowercase = 'abcdefghijklmnopqrstuvwxyz' ascii_uppercase = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ' ascii_letters = ascii_lowercase + ascii_uppercase digits = '0123456789' hexdigits = digits + 'abcdef' + 'ABCDEF' octdigits = '01234567' punctuation = r"""!"#$%&'()*+,-./:;<=>?@[\]^_`{|}~""" printable = digits + ascii_letters + punctuation + whitespace # Functions which aren't available as string methods. # Capitalize the words in a string, e.g. " aBc dEf " -> "Abc Def". def capwords(s, sep=None): """capwords(s [,sep]) -> string Split the argument into words using split, capitalize each word using capitalize, and join the capitalized words using join. If the optional second argument sep is absent or None, runs of whitespace characters are replaced by a single space and leading and trailing whitespace are removed, otherwise sep is used to split and join the words. """ return (sep or ' ').join(x.capitalize() for x in s.split(sep)) #################################################################### import re as _re from collections import ChainMap as _ChainMap class _TemplateMetaclass(type): pattern = r""" %(delim)s(?: (?P<escaped>%(delim)s) | # Escape sequence of two delimiters (?P<named>%(id)s) | # delimiter and a Python identifier {(?P<braced>%(id)s)} | # delimiter and a braced identifier (?P<invalid>) # Other ill-formed delimiter exprs ) """ def __init__(cls, name, bases, dct): super(_TemplateMetaclass, cls).__init__(name, bases, dct) if 'pattern' in dct: pattern = cls.pattern else: pattern = _TemplateMetaclass.pattern % { 'delim' : _re.escape(cls.delimiter), 'id' : cls.idpattern, } cls.pattern = _re.compile(pattern, cls.flags | _re.VERBOSE) class Template(metaclass=_TemplateMetaclass): """A string class for supporting $-substitutions.""" delimiter = '$' idpattern = r'[_a-z][_a-z0-9]*' flags = _re.IGNORECASE def __init__(self, template): self.template = template # Search for $$, $identifier, ${identifier}, and any bare $'s def _invalid(self, mo): i = mo.start('invalid') lines = self.template[:i].splitlines(keepends=True) if not lines: colno = 1 lineno = 1 else: colno = i - len(''.join(lines[:-1])) lineno = len(lines) raise ValueError('Invalid placeholder in string: line %d, col %d' % (lineno, colno)) def substitute(*args, **kws): if not args: raise TypeError("descriptor 'substitute' of 'Template' object " "needs an argument") self, *args = args # allow the "self" keyword be passed if len(args) > 1: raise TypeError('Too many positional arguments') if not args: mapping = kws elif kws: mapping = _ChainMap(kws, args[0]) else: mapping = args[0] # Helper function for .sub() def convert(mo): # Check the most common path first. named = mo.group('named') or mo.group('braced') if named is not None: return str(mapping[named]) if mo.group('escaped') is not None: return self.delimiter if mo.group('invalid') is not None: self._invalid(mo) raise ValueError('Unrecognized named group in pattern', self.pattern) return self.pattern.sub(convert, self.template) def safe_substitute(*args, **kws): if not args: raise TypeError("descriptor 'safe_substitute' of 'Template' object " "needs an argument") self, *args = args # allow the "self" keyword be passed if len(args) > 1: raise TypeError('Too many positional arguments') if not args: mapping = kws elif kws: mapping = _ChainMap(kws, args[0]) else: mapping = args[0] # Helper function for .sub() def convert(mo): named = mo.group('named') or mo.group('braced') if named is not None: try: return str(mapping[named]) except KeyError: return mo.group() if mo.group('escaped') is not None: return self.delimiter if mo.group('invalid') is not None: return mo.group() raise ValueError('Unrecognized named group in pattern', self.pattern) return self.pattern.sub(convert, self.template) ######################################################################## # the Formatter class # see PEP 3101 for details and purpose of this class # The hard parts are reused from the C implementation. They're exposed as "_" # prefixed methods of str. # The overall parser is implemented in _string.formatter_parser. # The field name parser is implemented in _string.formatter_field_name_split class Formatter: def format(*args, **kwargs): if not args: raise TypeError("descriptor 'format' of 'Formatter' object " "needs an argument") self, *args = args # allow the "self" keyword be passed try: format_string, *args = args # allow the "format_string" keyword be passed except ValueError: if 'format_string' in kwargs: format_string = kwargs.pop('format_string') import warnings warnings.warn("Passing 'format_string' as keyword argument is " "deprecated", DeprecationWarning, stacklevel=2) else: raise TypeError("format() missing 1 required positional " "argument: 'format_string'") from None return self.vformat(format_string, args, kwargs) def vformat(self, format_string, args, kwargs): used_args = set() result, _ = self._vformat(format_string, args, kwargs, used_args, 2) self.check_unused_args(used_args, args, kwargs) return result def _vformat(self, format_string, args, kwargs, used_args, recursion_depth, auto_arg_index=0): if recursion_depth < 0: raise ValueError('Max string recursion exceeded') result = [] for literal_text, field_name, format_spec, conversion in \ self.parse(format_string): # output the literal text if literal_text: result.append(literal_text) # if there's a field, output it if field_name is not None: # this is some markup, find the object and do # the formatting # handle arg indexing when empty field_names are given. if field_name == '': if auto_arg_index is False: raise ValueError('cannot switch from manual field ' 'specification to automatic field ' 'numbering') field_name = str(auto_arg_index) auto_arg_index += 1 elif field_name.isdigit(): if auto_arg_index: raise ValueError('cannot switch from manual field ' 'specification to automatic field ' 'numbering') # disable auto arg incrementing, if it gets # used later on, then an exception will be raised auto_arg_index = False # given the field_name, find the object it references # and the argument it came from obj, arg_used = self.get_field(field_name, args, kwargs) used_args.add(arg_used) # do any conversion on the resulting object obj = self.convert_field(obj, conversion) # expand the format spec, if needed format_spec, auto_arg_index = self._vformat( format_spec, args, kwargs, used_args, recursion_depth-1, auto_arg_index=auto_arg_index) # format the object and append to the result result.append(self.format_field(obj, format_spec)) return ''.join(result), auto_arg_index def get_value(self, key, args, kwargs): if isinstance(key, int): return args[key] else: return kwargs[key] def check_unused_args(self, used_args, args, kwargs): pass def format_field(self, value, format_spec): return format(value, format_spec) def convert_field(self, value, conversion): # do any conversion on the resulting object if conversion is None: return value elif conversion == 's': return str(value) elif conversion == 'r': return repr(value) elif conversion == 'a': return ascii(value) raise ValueError("Unknown conversion specifier {0!s}".format(conversion)) # returns an iterable that contains tuples of the form: # (literal_text, field_name, format_spec, conversion) # literal_text can be zero length # field_name can be None, in which case there's no # object to format and output # if field_name is not None, it is looked up, formatted # with format_spec and conversion and then used def parse(self, format_string): return _string.formatter_parser(format_string) # given a field_name, find the object it references. # field_name: the field being looked up, e.g. "0.name" # or "lookup[3]" # used_args: a set of which args have been used # args, kwargs: as passed in to vformat def get_field(self, field_name, args, kwargs): first, rest = _string.formatter_field_name_split(field_name) obj = self.get_value(first, args, kwargs) # loop through the rest of the field_name, doing # getattr or getitem as needed for is_attr, i in rest: if is_attr: obj = getattr(obj, i) else: obj = obj[i] return obj, first