Source code for leo.external.concurrent.futures._compat

from keyword import iskeyword as _iskeyword
from operator import itemgetter as _itemgetter
import sys as _sys


[docs]def namedtuple(typename, field_names): """Returns a new subclass of tuple with named fields. >>> Point = namedtuple('Point', 'x y') >>> Point.__doc__ # docstring for the new class 'Point(x, y)' >>> p = Point(11, y=22) # instantiate with positional args or keywords >>> p[0] + p[1] # indexable like a plain tuple 33 >>> x, y = p # unpack like a regular tuple >>> x, y (11, 22) >>> p.x + p.y # fields also accessable by name 33 >>> d = p._asdict() # convert to a dictionary >>> d['x'] 11 >>> Point(**d) # convert from a dictionary Point(x=11, y=22) >>> p._replace(x=100) # _replace() is like str.replace() but targets named fields Point(x=100, y=22) """ # Parse and validate the field names. Validation serves two purposes, # generating informative error messages and preventing template injection attacks. if isinstance(field_names, basestring): field_names = field_names.replace(',', ' ').split() # names separated by whitespace and/or commas field_names = tuple(map(str, field_names)) for name in (typename,) + field_names: if not all(c.isalnum() or c=='_' for c in name): raise ValueError('Type names and field names can only contain alphanumeric characters and underscores: %r' % name) if _iskeyword(name): raise ValueError('Type names and field names cannot be a keyword: %r' % name) if name[0].isdigit(): raise ValueError('Type names and field names cannot start with a number: %r' % name) seen_names = set() for name in field_names: if name.startswith('_'): raise ValueError('Field names cannot start with an underscore: %r' % name) if name in seen_names: raise ValueError('Encountered duplicate field name: %r' % name) seen_names.add(name) # Create and fill-in the class template numfields = len(field_names) argtxt = repr(field_names).replace("'", "")[1:-1] # tuple repr without parens or quotes reprtxt = ', '.join('%s=%%r' % name for name in field_names) dicttxt = ', '.join('%r: t[%d]' % (name, pos) for pos, name in enumerate(field_names)) template = '''class %(typename)s(tuple): '%(typename)s(%(argtxt)s)' \n __slots__ = () \n _fields = %(field_names)r \n def __new__(_cls, %(argtxt)s): return _tuple.__new__(_cls, (%(argtxt)s)) \n @classmethod def _make(cls, iterable, new=tuple.__new__, len=len): 'Make a new %(typename)s object from a sequence or iterable' result = new(cls, iterable) if len(result) != %(numfields)d: raise TypeError('Expected %(numfields)d arguments, got %%d' %% len(result)) return result \n def __repr__(self): return '%(typename)s(%(reprtxt)s)' %% self \n def _asdict(t): 'Return a new dict which maps field names to their values' return {%(dicttxt)s} \n def _replace(_self, **kwds): 'Return a new %(typename)s object replacing specified fields with new values' result = _self._make(map(kwds.pop, %(field_names)r, _self)) if kwds: raise ValueError('Got unexpected field names: %%r' %% kwds.keys()) return result \n def __getnewargs__(self): return tuple(self) \n\n''' % locals() for i, name in enumerate(field_names): template += ' %s = _property(_itemgetter(%d))\n' % (name, i) # Execute the template string in a temporary namespace and # support tracing utilities by setting a value for frame.f_globals['__name__'] namespace = dict(_itemgetter=_itemgetter, __name__='namedtuple_%s' % typename, _property=property, _tuple=tuple) try: exec(template, namespace) except SyntaxError: e = _sys.exc_info()[1] raise SyntaxError(e.message + ':\n' + template) result = namespace[typename] # For pickling to work, the __module__ variable needs to be set to the frame # where the named tuple is created. Bypass this step in enviroments where # sys._getframe is not defined (Jython for example). if hasattr(_sys, '_getframe'): result.__module__ = _sys._getframe(1).f_globals.get('__name__', '__main__') return result