cpython/Lib/importlib/__init__.py

125 lines
3.1 KiB
Python

"""A pure Python implementation of import.
References on import:
* Language reference
http://docs.python.org/ref/import.html
* __import__ function
http://docs.python.org/lib/built-in-funcs.html
* Packages
http://www.python.org/doc/essays/packages.html
* PEP 235: Import on Case-Insensitive Platforms
http://www.python.org/dev/peps/pep-0235
* PEP 275: Import Modules from Zip Archives
http://www.python.org/dev/peps/pep-0273
* PEP 302: New Import Hooks
http://www.python.org/dev/peps/pep-0302/
* PEP 328: Imports: Multi-line and Absolute/Relative
http://www.python.org/dev/peps/pep-0328
"""
__all__ = ['__import__', 'import_module']
from . import _bootstrap
import os
import re
import tokenize
# Bootstrap help #####################################################
def _case_ok(directory, check):
"""Check if the directory contains something matching 'check'.
No check is done if the file/directory exists or not.
"""
if 'PYTHONCASEOK' in os.environ:
return True
elif check in os.listdir(directory):
return True
return False
def _w_long(x):
"""Convert a 32-bit integer to little-endian.
XXX Temporary until marshal's long functions are exposed.
"""
x = int(x)
int_bytes = []
int_bytes.append(x & 0xFF)
int_bytes.append((x >> 8) & 0xFF)
int_bytes.append((x >> 16) & 0xFF)
int_bytes.append((x >> 24) & 0xFF)
return bytearray(int_bytes)
def _r_long(int_bytes):
"""Convert 4 bytes in little-endian to an integer.
XXX Temporary until marshal's long function are exposed.
"""
x = int_bytes[0]
x |= int_bytes[1] << 8
x |= int_bytes[2] << 16
x |= int_bytes[3] << 24
return x
# Required built-in modules.
try:
import posix as _os
except ImportError:
try:
import nt as _os
except ImportError:
try:
import os2 as _os
except ImportError:
raise ImportError('posix, nt, or os2 module required for importlib')
_bootstrap._os = _os
import imp, sys, marshal, errno, _io
_bootstrap.imp = imp
_bootstrap.sys = sys
_bootstrap.marshal = marshal
_bootstrap.errno = errno
_bootstrap._io = _io
import _warnings
_bootstrap._warnings = _warnings
from os import sep
# For os.path.join replacement; pull from Include/osdefs.h:SEP .
_bootstrap.path_sep = sep
_bootstrap._case_ok = _case_ok
marshal._w_long = _w_long
marshal._r_long = _r_long
# Public API #########################################################
from ._bootstrap import __import__
def import_module(name, package=None):
"""Import a module.
The 'package' argument is required when performing a relative import. It
specifies the package to use as the anchor point from which to resolve the
relative import to an absolute import.
"""
level = 0
if name.startswith('.'):
if not package:
raise TypeError("relative imports require the 'package' argument")
for character in name:
if character != '.':
break
level += 1
return _bootstrap._gcd_import(name[level:], package, level)