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# demandimport.py - global demand-loading of modules for Mercurial
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#
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# Copyright 2006, 2007 Matt Mackall <mpm@selenic.com>
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#
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# This software may be used and distributed according to the terms
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# of the GNU General Public License, incorporated herein by reference.
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'''
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demandimport - automatic demandloading of modules
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To enable this module, do:
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import demandimport; demandimport.enable()
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Imports of the following forms will be demand-loaded:
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import a, b.c
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import a.b as c
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from a import b,c # a will be loaded immediately
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These imports will not be delayed:
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from a import *
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b = __import__(a)
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'''
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_origimport = __import__
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class _demandmod(object):
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"""module demand-loader and proxy"""
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def __init__(self, name, globals, locals):
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if '.' in name:
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head, rest = name.split('.', 1)
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after = [rest]
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else:
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head = name
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after = []
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object.__setattr__(self, "_data", (head, globals, locals, after))
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object.__setattr__(self, "_module", None)
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def _extend(self, name):
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"""add to the list of submodules to load"""
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self._data[3].append(name)
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def _load(self):
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if not self._module:
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head, globals, locals, after = self._data
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mod = _origimport(head, globals, locals)
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# load submodules
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def subload(mod, p):
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h, t = p, None
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if '.' in p:
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h, t = p.split('.', 1)
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if not hasattr(mod, h):
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setattr(mod, h, _demandmod(p, mod.__dict__, mod.__dict__))
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elif t:
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subload(getattr(mod, h), t)
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for x in after:
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subload(mod, x)
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# are we in the locals dictionary still?
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if locals and locals.get(head) == self:
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locals[head] = mod
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object.__setattr__(self, "_module", mod)
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def __repr__(self):
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if self._module:
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return "<proxied module '%s'>" % self._data[0]
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return "<unloaded module '%s'>" % self._data[0]
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def __call__(self, *args, **kwargs):
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raise TypeError("%s object is not callable" % repr(self))
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def __getattribute__(self, attr):
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if attr in ('_data', '_extend', '_load', '_module'):
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return object.__getattribute__(self, attr)
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self._load()
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return getattr(self._module, attr)
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def __setattr__(self, attr, val):
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self._load()
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setattr(self._module, attr, val)
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def _demandimport(name, globals=None, locals=None, fromlist=None):
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if not locals or name in ignore or fromlist == ('*',):
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# these cases we can't really delay
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return _origimport(name, globals, locals, fromlist)
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elif not fromlist:
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# import a [as b]
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if '.' in name: # a.b
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base, rest = name.split('.', 1)
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# email.__init__ loading email.mime
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if globals and globals.get('__name__', None) == base:
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return _origimport(name, globals, locals, fromlist)
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# if a is already demand-loaded, add b to its submodule list
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if base in locals:
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if isinstance(locals[base], _demandmod):
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locals[base]._extend(rest)
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return locals[base]
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return _demandmod(name, globals, locals)
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else:
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# from a import b,c,d
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mod = _origimport(name, globals, locals)
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# recurse down the module chain
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for comp in name.split('.')[1:]:
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if not hasattr(mod, comp):
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setattr(mod, comp, _demandmod(comp, mod.__dict__, mod.__dict__))
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mod = getattr(mod, comp)
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for x in fromlist:
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# set requested submodules for demand load
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if not(hasattr(mod, x)):
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setattr(mod, x, _demandmod(x, mod.__dict__, locals))
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return mod
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ignore = [
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'_hashlib',
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'_xmlplus',
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'fcntl',
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'win32com.gen_py',
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# imported by tarfile, not available under Windows
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'pwd',
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'grp',
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# imported by profile, itself imported by hotshot.stats,
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# not available under Windows
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'resource',
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]
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def enable():
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"enable global demand-loading of modules"
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__builtins__["__import__"] = _demandimport
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def disable():
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"disable global demand-loading of modules"
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__builtins__["__import__"] = _origimport
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