diff -r d02888308235 -r 0906b85bf222 mercurial/demandimport.py --- a/mercurial/demandimport.py Sun May 21 12:09:01 2017 -0700 +++ /dev/null Thu Jan 01 00:00:00 1970 +0000 @@ -1,332 +0,0 @@ -# demandimport.py - global demand-loading of modules for Mercurial -# -# Copyright 2006, 2007 Matt Mackall -# -# This software may be used and distributed according to the terms of the -# GNU General Public License version 2 or any later version. - -''' -demandimport - automatic demandloading of modules - -To enable this module, do: - - import demandimport; demandimport.enable() - -Imports of the following forms will be demand-loaded: - - import a, b.c - import a.b as c - from a import b,c # a will be loaded immediately - -These imports will not be delayed: - - from a import * - b = __import__(a) -''' - -from __future__ import absolute_import - -import contextlib -import os -import sys - -# __builtin__ in Python 2, builtins in Python 3. -try: - import __builtin__ as builtins -except ImportError: - import builtins - -contextmanager = contextlib.contextmanager - -_origimport = __import__ - -nothing = object() - -# Python 3 doesn't have relative imports nor level -1. -level = -1 -if sys.version_info[0] >= 3: - level = 0 -_import = _origimport - -def _hgextimport(importfunc, name, globals, *args, **kwargs): - try: - return importfunc(name, globals, *args, **kwargs) - except ImportError: - if not globals: - raise - # extensions are loaded with "hgext_" prefix - hgextname = 'hgext_%s' % name - nameroot = hgextname.split('.', 1)[0] - contextroot = globals.get('__name__', '').split('.', 1)[0] - if nameroot != contextroot: - raise - # retry to import with "hgext_" prefix - return importfunc(hgextname, globals, *args, **kwargs) - -class _demandmod(object): - """module demand-loader and proxy - - Specify 1 as 'level' argument at construction, to import module - relatively. - """ - def __init__(self, name, globals, locals, level): - if '.' in name: - head, rest = name.split('.', 1) - after = [rest] - else: - head = name - after = [] - object.__setattr__(self, r"_data", - (head, globals, locals, after, level, set())) - object.__setattr__(self, r"_module", None) - def _extend(self, name): - """add to the list of submodules to load""" - self._data[3].append(name) - - def _addref(self, name): - """Record that the named module ``name`` imports this module. - - References to this proxy class having the name of this module will be - replaced at module load time. We assume the symbol inside the importing - module is identical to the "head" name of this module. We don't - actually know if "as X" syntax is being used to change the symbol name - because this information isn't exposed to __import__. - """ - self._data[5].add(name) - - def _load(self): - if not self._module: - head, globals, locals, after, level, modrefs = self._data - mod = _hgextimport(_import, head, globals, locals, None, level) - if mod is self: - # In this case, _hgextimport() above should imply - # _demandimport(). Otherwise, _hgextimport() never - # returns _demandmod. This isn't intentional behavior, - # in fact. (see also issue5304 for detail) - # - # If self._module is already bound at this point, self - # should be already _load()-ed while _hgextimport(). - # Otherwise, there is no way to import actual module - # as expected, because (re-)invoking _hgextimport() - # should cause same result. - # This is reason why _load() returns without any more - # setup but assumes self to be already bound. - mod = self._module - assert mod and mod is not self, "%s, %s" % (self, mod) - return - - # load submodules - def subload(mod, p): - h, t = p, None - if '.' in p: - h, t = p.split('.', 1) - if getattr(mod, h, nothing) is nothing: - setattr(mod, h, _demandmod(p, mod.__dict__, mod.__dict__, - level=1)) - elif t: - subload(getattr(mod, h), t) - - for x in after: - subload(mod, x) - - # Replace references to this proxy instance with the actual module. - if locals and locals.get(head) == self: - locals[head] = mod - - for modname in modrefs: - modref = sys.modules.get(modname, None) - if modref and getattr(modref, head, None) == self: - setattr(modref, head, mod) - - object.__setattr__(self, r"_module", mod) - - def __repr__(self): - if self._module: - return "" % self._data[0] - return "" % self._data[0] - def __call__(self, *args, **kwargs): - raise TypeError("%s object is not callable" % repr(self)) - def __getattribute__(self, attr): - if attr in ('_data', '_extend', '_load', '_module', '_addref'): - return object.__getattribute__(self, attr) - self._load() - return getattr(self._module, attr) - def __setattr__(self, attr, val): - self._load() - setattr(self._module, attr, val) - -_pypy = '__pypy__' in sys.builtin_module_names - -def _demandimport(name, globals=None, locals=None, fromlist=None, level=level): - if locals is None or name in ignore or fromlist == ('*',): - # these cases we can't really delay - return _hgextimport(_import, name, globals, locals, fromlist, level) - elif not fromlist: - # import a [as b] - if '.' in name: # a.b - base, rest = name.split('.', 1) - # email.__init__ loading email.mime - if globals and globals.get('__name__', None) == base: - return _import(name, globals, locals, fromlist, level) - # if a is already demand-loaded, add b to its submodule list - if base in locals: - if isinstance(locals[base], _demandmod): - locals[base]._extend(rest) - return locals[base] - return _demandmod(name, globals, locals, level) - else: - # There is a fromlist. - # from a import b,c,d - # from . import b,c,d - # from .a import b,c,d - - # level == -1: relative and absolute attempted (Python 2 only). - # level >= 0: absolute only (Python 2 w/ absolute_import and Python 3). - # The modern Mercurial convention is to use absolute_import everywhere, - # so modern Mercurial code will have level >= 0. - - # The name of the module the import statement is located in. - globalname = globals.get('__name__') - - def processfromitem(mod, attr): - """Process an imported symbol in the import statement. - - If the symbol doesn't exist in the parent module, and if the - parent module is a package, it must be a module. We set missing - modules up as _demandmod instances. - """ - symbol = getattr(mod, attr, nothing) - nonpkg = getattr(mod, '__path__', nothing) is nothing - if symbol is nothing: - if nonpkg: - # do not try relative import, which would raise ValueError, - # and leave unknown attribute as the default __import__() - # would do. the missing attribute will be detected later - # while processing the import statement. - return - mn = '%s.%s' % (mod.__name__, attr) - if mn in ignore: - importfunc = _origimport - else: - importfunc = _demandmod - symbol = importfunc(attr, mod.__dict__, locals, level=1) - setattr(mod, attr, symbol) - - # Record the importing module references this symbol so we can - # replace the symbol with the actual module instance at load - # time. - if globalname and isinstance(symbol, _demandmod): - symbol._addref(globalname) - - def chainmodules(rootmod, modname): - # recurse down the module chain, and return the leaf module - mod = rootmod - for comp in modname.split('.')[1:]: - if getattr(mod, comp, nothing) is nothing: - setattr(mod, comp, _demandmod(comp, mod.__dict__, - mod.__dict__, level=1)) - mod = getattr(mod, comp) - return mod - - if level >= 0: - if name: - # "from a import b" or "from .a import b" style - rootmod = _hgextimport(_origimport, name, globals, locals, - level=level) - mod = chainmodules(rootmod, name) - elif _pypy: - # PyPy's __import__ throws an exception if invoked - # with an empty name and no fromlist. Recreate the - # desired behaviour by hand. - mn = globalname - mod = sys.modules[mn] - if getattr(mod, '__path__', nothing) is nothing: - mn = mn.rsplit('.', 1)[0] - mod = sys.modules[mn] - if level > 1: - mn = mn.rsplit('.', level - 1)[0] - mod = sys.modules[mn] - else: - mod = _hgextimport(_origimport, name, globals, locals, - level=level) - - for x in fromlist: - processfromitem(mod, x) - - return mod - - # But, we still need to support lazy loading of standard library and 3rd - # party modules. So handle level == -1. - mod = _hgextimport(_origimport, name, globals, locals) - mod = chainmodules(mod, name) - - for x in fromlist: - processfromitem(mod, x) - - return mod - -ignore = [ - '__future__', - '_hashlib', - # ImportError during pkg_resources/__init__.py:fixup_namespace_package - '_imp', - '_xmlplus', - 'fcntl', - 'nt', # pathlib2 tests the existence of built-in 'nt' module - 'win32com.gen_py', - 'win32com.shell', # 'appdirs' tries to import win32com.shell - '_winreg', # 2.7 mimetypes needs immediate ImportError - 'pythoncom', - # imported by tarfile, not available under Windows - 'pwd', - 'grp', - # imported by profile, itself imported by hotshot.stats, - # not available under Windows - 'resource', - # this trips up many extension authors - 'gtk', - # setuptools' pkg_resources.py expects "from __main__ import x" to - # raise ImportError if x not defined - '__main__', - '_ssl', # conditional imports in the stdlib, issue1964 - '_sre', # issue4920 - 'rfc822', - 'mimetools', - 'sqlalchemy.events', # has import-time side effects (issue5085) - # setuptools 8 expects this module to explode early when not on windows - 'distutils.msvc9compiler', - '__builtin__', - 'builtins', - 'urwid.command_map', # for pudb - ] - -if _pypy: - ignore.extend([ - # _ctypes.pointer is shadowed by "from ... import pointer" (PyPy 5) - '_ctypes.pointer', - ]) - -def isenabled(): - return builtins.__import__ == _demandimport - -def enable(): - "enable global demand-loading of modules" - if os.environ.get('HGDEMANDIMPORT') != 'disable': - builtins.__import__ = _demandimport - -def disable(): - "disable global demand-loading of modules" - builtins.__import__ = _origimport - -@contextmanager -def deactivated(): - "context manager for disabling demandimport in 'with' blocks" - demandenabled = isenabled() - if demandenabled: - disable() - - try: - yield - finally: - if demandenabled: - enable()