mirror of
https://github.com/python/cpython.git
synced 2024-11-25 19:03:49 +08:00
113 lines
4.4 KiB
Python
113 lines
4.4 KiB
Python
__all__ = ['deque', 'defaultdict', 'namedtuple']
|
|
|
|
from _collections import deque, defaultdict
|
|
from operator import itemgetter as _itemgetter
|
|
from keyword import iskeyword as _iskeyword
|
|
import sys as _sys
|
|
|
|
# For bootstrapping reasons, the collection ABCs are defined in _abcoll.py.
|
|
# They should however be considered an integral part of collections.py.
|
|
from _abcoll import *
|
|
import _abcoll
|
|
__all__ += _abcoll.__all__
|
|
|
|
def namedtuple(typename, field_names, verbose=False):
|
|
"""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] # works just like the tuple (11, 22)
|
|
33
|
|
>>> x, y = p # unpacks just like a 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
|
|
if isinstance(field_names, str):
|
|
field_names = field_names.replace(',', ' ').split() # names separated by whitespace and/or commas
|
|
field_names = tuple(field_names)
|
|
for name in (typename,) + field_names:
|
|
if not name.replace('_', '').isalnum():
|
|
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('__') and name.endswith('__'):
|
|
raise ValueError('Field names cannot start and end with double underscores: %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
|
|
argtxt = repr(field_names).replace("'", "")[1:-1] # tuple repr without parens or quotes
|
|
reprtxt = ', '.join('%s=%%r' % name for name in field_names)
|
|
template = '''class %(typename)s(tuple):
|
|
'%(typename)s(%(argtxt)s)'
|
|
__slots__ = ()
|
|
__fields__ = property(lambda self: %(field_names)r)
|
|
def __new__(cls, %(argtxt)s):
|
|
return tuple.__new__(cls, (%(argtxt)s))
|
|
def __repr__(self):
|
|
return '%(typename)s(%(reprtxt)s)' %% self
|
|
def __asdict__(self, dict=dict, zip=zip):
|
|
'Return a new dict mapping field names to their values'
|
|
return dict(zip(%(field_names)r, self))
|
|
def __replace__(self, **kwds):
|
|
'Return a new %(typename)s object replacing specified fields with new values'
|
|
return %(typename)s(**dict(list(zip(%(field_names)r, self)) + list(kwds.items()))) \n''' % locals()
|
|
for i, name in enumerate(field_names):
|
|
template += ' %s = property(itemgetter(%d))\n' % (name, i)
|
|
if verbose:
|
|
print(template)
|
|
|
|
# Execute the template string in a temporary namespace
|
|
namespace = dict(itemgetter=_itemgetter)
|
|
try:
|
|
exec(template, namespace)
|
|
except SyntaxError as e:
|
|
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['__name__']
|
|
|
|
return result
|
|
|
|
|
|
|
|
|
|
|
|
if __name__ == '__main__':
|
|
# verify that instances can be pickled
|
|
from pickle import loads, dumps
|
|
Point = namedtuple('Point', 'x, y', True)
|
|
p = Point(x=10, y=20)
|
|
assert p == loads(dumps(p))
|
|
|
|
# test and demonstrate ability to override methods
|
|
Point.__repr__ = lambda self: 'Point(%.3f, %.3f)' % self
|
|
print(p)
|
|
|
|
import doctest
|
|
TestResults = namedtuple('TestResults', 'failed attempted')
|
|
print(TestResults(*doctest.testmod()))
|