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706 lines
22 KiB
Python
706 lines
22 KiB
Python
#
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# imputil.py
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#
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# Written by Greg Stein. Public Domain.
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# No Copyright, no Rights Reserved, and no Warranties.
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#
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# Utilities to help out with custom import mechanisms.
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#
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# Additional modifications were contribed by Marc-Andre Lemburg and
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# Gordon McMillan.
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#
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# This module is maintained by Greg and is available at:
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# http://www.lyra.org/greg/python/
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#
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# Since this isn't in the Python distribution yet, we'll use the CVS ID
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# for tracking:
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# $Id$
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#
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# note: avoid importing non-builtin modules
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import imp ### not available in JPython?
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import sys
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import strop
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import __builtin__
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# for the DirectoryImporter
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import struct
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import marshal
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_StringType = type('')
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_ModuleType = type(sys) ### doesn't work in JPython...
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class ImportManager:
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"Manage the import process."
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def install(self, namespace=vars(__builtin__)):
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"Install this ImportManager into the specified namespace."
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if isinstance(namespace, _ModuleType):
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namespace = vars(namespace)
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### Note that we have no notion of "uninstall" or "chaining"
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namespace['__import__'] = self._import_hook
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### fix this
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#namespace['reload'] = self._reload_hook
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def add_suffix(self, suffix, importFunc):
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assert callable(importFunc)
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self.fs_imp.add_suffix(suffix, importFunc)
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######################################################################
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#
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# PRIVATE METHODS
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#
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clsFilesystemImporter = None
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def __init__(self, fs_imp=None):
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# we're definitely going to be importing something in the future,
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# so let's just load the OS-related facilities.
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if not _os_stat:
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_os_bootstrap()
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# This is the Importer that we use for grabbing stuff from the
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# filesystem. It defines one more method (import_from_dir) for our use.
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if not fs_imp:
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cls = self.clsFilesystemImporter or _FilesystemImporter
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fs_imp = cls()
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self.fs_imp = fs_imp
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# Initialize the set of suffixes that we recognize and import.
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# The default will import dynamic-load modules first, followed by
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# .py files (or a .py file's cached bytecode)
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for desc in imp.get_suffixes():
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if desc[2] == imp.C_EXTENSION:
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self.add_suffix(desc[0], DynLoadSuffixImporter(desc).import_file)
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self.add_suffix('.py', py_suffix_importer)
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def _import_hook(self, fqname, globals=None, locals=None, fromlist=None):
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"""Python calls this hook to locate and import a module."""
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parts = strop.split(fqname, '.')
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# determine the context of this import
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parent = self._determine_import_context(globals)
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# if there is a parent, then its importer should manage this import
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if parent:
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module = parent.__importer__._do_import(parent, parts, fromlist)
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if module:
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return module
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# has the top module already been imported?
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try:
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top_module = sys.modules[parts[0]]
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except KeyError:
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# look for the topmost module
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top_module = self._import_top_module(parts[0])
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if not top_module:
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# the topmost module wasn't found at all.
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raise ImportError, 'No module named ' + fqname
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# fast-path simple imports
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if len(parts) == 1:
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if not fromlist:
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return top_module
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if not top_module.__dict__.get('__ispkg__'):
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# __ispkg__ isn't defined (the module was not imported by us), or
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# it is zero.
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#
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# In the former case, there is no way that we could import
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# sub-modules that occur in the fromlist (but we can't raise an
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# error because it may just be names) because we don't know how
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# to deal with packages that were imported by other systems.
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#
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# In the latter case (__ispkg__ == 0), there can't be any sub-
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# modules present, so we can just return.
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#
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# In both cases, since len(parts) == 1, the top_module is also
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# the "bottom" which is the defined return when a fromlist exists.
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return top_module
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importer = top_module.__dict__.get('__importer__')
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if importer:
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return importer._finish_import(top_module, parts[1:], fromlist)
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# If the importer does not exist, then we have to bail. A missing importer
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# means that something else imported the module, and we have no knowledge
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# of how to get sub-modules out of the thing.
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raise ImportError, 'No module named ' + fqname
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def _determine_import_context(self, globals):
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"""Returns the context in which a module should be imported.
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The context could be a loaded (package) module and the imported module
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will be looked for within that package. The context could also be None,
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meaning there is no context -- the module should be looked for as a
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"top-level" module.
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"""
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if not globals or not globals.get('__importer__'):
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# globals does not refer to one of our modules or packages. That
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# implies there is no relative import context (as far as we are
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# concerned), and it should just pick it off the standard path.
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return None
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# The globals refer to a module or package of ours. It will define
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# the context of the new import. Get the module/package fqname.
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parent_fqname = globals['__name__']
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# if a package is performing the import, then return itself (imports
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# refer to pkg contents)
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if globals['__ispkg__']:
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parent = sys.modules[parent_fqname]
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assert globals is parent.__dict__
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return parent
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i = strop.rfind(parent_fqname, '.')
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# a module outside of a package has no particular import context
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if i == -1:
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return None
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# if a module in a package is performing the import, then return the
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# package (imports refer to siblings)
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parent_fqname = parent_fqname[:i]
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parent = sys.modules[parent_fqname]
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assert parent.__name__ == parent_fqname
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return parent
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def _import_top_module(self, name):
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# scan sys.path looking for a location in the filesystem that contains
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# the module, or an Importer object that can import the module.
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for item in sys.path:
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if isinstance(item, _StringType):
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module = self.fs_imp.import_from_dir(item, name)
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else:
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module = item.import_top(name)
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if module:
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return module
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return None
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def _reload_hook(self, module):
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"Python calls this hook to reload a module."
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# reloading of a module may or may not be possible (depending on the
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# importer), but at least we can validate that it's ours to reload
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importer = module.__dict__.get('__importer__')
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if not importer:
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### oops. now what...
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pass
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# okay. it is using the imputil system, and we must delegate it, but
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# we don't know what to do (yet)
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### we should blast the module dict and do another get_code(). need to
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### flesh this out and add proper docco...
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raise SystemError, "reload not yet implemented"
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class Importer:
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"Base class for replacing standard import functions."
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def import_top(self, name):
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"Import a top-level module."
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return self._import_one(None, name, name)
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######################################################################
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#
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# PRIVATE METHODS
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#
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def _finish_import(self, top, parts, fromlist):
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# if "a.b.c" was provided, then load the ".b.c" portion down from
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# below the top-level module.
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bottom = self._load_tail(top, parts)
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# if the form is "import a.b.c", then return "a"
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if not fromlist:
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# no fromlist: return the top of the import tree
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return top
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# the top module was imported by self.
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#
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# this means that the bottom module was also imported by self (just
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# now, or in the past and we fetched it from sys.modules).
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#
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# since we imported/handled the bottom module, this means that we can
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# also handle its fromlist (and reliably use __ispkg__).
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# if the bottom node is a package, then (potentially) import some modules.
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#
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# note: if it is not a package, then "fromlist" refers to names in
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# the bottom module rather than modules.
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# note: for a mix of names and modules in the fromlist, we will
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# import all modules and insert those into the namespace of
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# the package module. Python will pick up all fromlist names
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# from the bottom (package) module; some will be modules that
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# we imported and stored in the namespace, others are expected
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# to be present already.
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if bottom.__ispkg__:
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self._import_fromlist(bottom, fromlist)
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# if the form is "from a.b import c, d" then return "b"
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return bottom
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def _import_one(self, parent, modname, fqname):
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"Import a single module."
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# has the module already been imported?
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try:
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return sys.modules[fqname]
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except KeyError:
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pass
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# load the module's code, or fetch the module itself
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result = self.get_code(parent, modname, fqname)
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if result is None:
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return None
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module = self._process_result(result, fqname)
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# insert the module into its parent
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if parent:
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setattr(parent, modname, module)
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return module
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def _process_result(self, (ispkg, code, values), fqname):
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# did get_code() return an actual module? (rather than a code object)
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is_module = isinstance(code, _ModuleType)
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# use the returned module, or create a new one to exec code into
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if is_module:
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module = code
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else:
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module = imp.new_module(fqname)
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### record packages a bit differently??
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module.__importer__ = self
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module.__ispkg__ = ispkg
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# insert additional values into the module (before executing the code)
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module.__dict__.update(values)
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# the module is almost ready... make it visible
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sys.modules[fqname] = module
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# execute the code within the module's namespace
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if not is_module:
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exec code in module.__dict__
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return module
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def _load_tail(self, m, parts):
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"""Import the rest of the modules, down from the top-level module.
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Returns the last module in the dotted list of modules.
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"""
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for part in parts:
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fqname = "%s.%s" % (m.__name__, part)
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m = self._import_one(m, part, fqname)
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if not m:
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raise ImportError, "No module named " + fqname
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return m
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def _import_fromlist(self, package, fromlist):
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'Import any sub-modules in the "from" list.'
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# if '*' is present in the fromlist, then look for the '__all__' variable
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# to find additional items (modules) to import.
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if '*' in fromlist:
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fromlist = list(fromlist) + list(package.__dict__.get('__all__', []))
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for sub in fromlist:
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# if the name is already present, then don't try to import it (it
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# might not be a module!).
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if sub != '*' and not hasattr(package, sub):
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subname = "%s.%s" % (package.__name__, sub)
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submod = self._import_one(package, sub, subname)
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if not submod:
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raise ImportError, "cannot import name " + subname
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def _do_import(self, parent, parts, fromlist):
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"""Attempt to import the module relative to parent.
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This method is used when the import context specifies that <self>
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imported the parent module.
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"""
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top_name = parts[0]
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top_fqname = parent.__name__ + '.' + top_name
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top_module = self._import_one(parent, top_name, top_fqname)
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if not top_module:
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# this importer and parent could not find the module (relatively)
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return None
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return self._finish_import(top_module, parts[1:], fromlist)
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######################################################################
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#
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# METHODS TO OVERRIDE
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#
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def get_code(self, parent, modname, fqname):
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"""Find and retrieve the code for the given module.
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parent specifies a parent module to define a context for importing. It
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may be None, indicating no particular context for the search.
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modname specifies a single module (not dotted) within the parent.
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fqname specifies the fully-qualified module name. This is a (potentially)
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dotted name from the "root" of the module namespace down to the modname.
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If there is no parent, then modname==fqname.
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This method should return None, or a 3-tuple.
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* If the module was not found, then None should be returned.
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* The first item of the 2- or 3-tuple should be the integer 0 or 1,
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specifying whether the module that was found is a package or not.
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* The second item is the code object for the module (it will be
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executed within the new module's namespace). This item can also
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be a fully-loaded module object (e.g. loaded from a shared lib).
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* The third item is a dictionary of name/value pairs that will be
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inserted into new module before the code object is executed. This
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is provided in case the module's code expects certain values (such
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as where the module was found). When the second item is a module
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object, then these names/values will be inserted *after* the module
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has been loaded/initialized.
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"""
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raise RuntimeError, "get_code not implemented"
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######################################################################
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#
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# Some handy stuff for the Importers
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#
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# byte-compiled file suffix character
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_suffix_char = __debug__ and 'c' or 'o'
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# byte-compiled file suffix
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_suffix = '.py' + _suffix_char
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def _compile(pathname, timestamp):
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"""Compile (and cache) a Python source file.
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The file specified by <pathname> is compiled to a code object and
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returned.
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Presuming the appropriate privileges exist, the bytecodes will be
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saved back to the filesystem for future imports. The source file's
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modification timestamp must be provided as a Long value.
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"""
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codestring = open(pathname, 'r').read()
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if codestring and codestring[-1] != '\n':
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codestring = codestring + '\n'
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code = __builtin__.compile(codestring, pathname, 'exec')
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# try to cache the compiled code
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try:
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f = open(pathname + _suffix_char, 'wb')
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except IOError:
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pass
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else:
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f.write('\0\0\0\0')
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f.write(struct.pack('<I', timestamp))
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marshal.dump(code, f)
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f.flush()
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f.seek(0, 0)
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f.write(imp.get_magic())
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f.close()
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return code
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_os_stat = _os_path_join = None
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def _os_bootstrap():
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"Set up 'os' module replacement functions for use during import bootstrap."
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names = sys.builtin_module_names
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join = None
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if 'posix' in names:
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sep = '/'
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from posix import stat
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elif 'nt' in names:
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sep = '\\'
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from nt import stat
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elif 'dos' in names:
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sep = '\\'
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from dos import stat
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elif 'os2' in names:
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sep = '\\'
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from os2 import stat
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elif 'mac' in names:
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from mac import stat
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def join(a, b):
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if a == '':
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return b
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path = s
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if ':' not in a:
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a = ':' + a
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if a[-1:] <> ':':
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a = a + ':'
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return a + b
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else:
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raise ImportError, 'no os specific module found'
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if join is None:
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def join(a, b, sep=sep):
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if a == '':
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return b
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lastchar = a[-1:]
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if lastchar == '/' or lastchar == sep:
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return a + b
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return a + sep + b
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global _os_stat
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_os_stat = stat
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global _os_path_join
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_os_path_join = join
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def _os_path_isdir(pathname):
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"Local replacement for os.path.isdir()."
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try:
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s = _os_stat(pathname)
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except OSError:
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return None
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return (s[0] & 0170000) == 0040000
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def _timestamp(pathname):
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"Return the file modification time as a Long."
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try:
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s = _os_stat(pathname)
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except OSError:
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return None
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return long(s[8])
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######################################################################
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#
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# Emulate the import mechanism for builtin and frozen modules
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#
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class BuiltinImporter(Importer):
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def get_code(self, parent, modname, fqname):
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if parent:
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# these modules definitely do not occur within a package context
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return None
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# look for the module
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if imp.is_builtin(modname):
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type = imp.C_BUILTIN
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elif imp.is_frozen(modname):
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type = imp.PY_FROZEN
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else:
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# not found
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return None
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# got it. now load and return it.
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module = imp.load_module(modname, None, modname, ('', '', type))
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return 0, module, { }
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######################################################################
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#
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# Internal importer used for importing from the filesystem
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#
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class _FilesystemImporter(Importer):
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def __init__(self):
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self.suffixes = [ ]
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def add_suffix(self, suffix, importFunc):
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assert callable(importFunc)
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self.suffixes.append((suffix, importFunc))
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def import_from_dir(self, dir, fqname):
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result = self._import_pathname(_os_path_join(dir, fqname), fqname)
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if result:
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return self._process_result(result, fqname)
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return None
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def get_code(self, parent, modname, fqname):
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# This importer is never used with an empty parent. Its existence is
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# private to the ImportManager. The ImportManager uses the
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# import_from_dir() method to import top-level modules/packages.
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# This method is only used when we look for a module within a package.
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assert parent
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return self._import_pathname(_os_path_join(parent.__pkgdir__, modname),
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fqname)
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|
def _import_pathname(self, pathname, fqname):
|
|
if _os_path_isdir(pathname):
|
|
result = self._import_pathname(_os_path_join(pathname, '__init__'),
|
|
fqname)
|
|
if result:
|
|
values = result[2]
|
|
values['__pkgdir__'] = pathname
|
|
values['__path__'] = [ pathname ]
|
|
return 1, result[1], values
|
|
return None
|
|
|
|
for suffix, importFunc in self.suffixes:
|
|
filename = pathname + suffix
|
|
try:
|
|
finfo = _os_stat(filename)
|
|
except OSError:
|
|
pass
|
|
else:
|
|
return importFunc(filename, finfo, fqname)
|
|
return None
|
|
|
|
######################################################################
|
|
#
|
|
# SUFFIX-BASED IMPORTERS
|
|
#
|
|
|
|
def py_suffix_importer(filename, finfo, fqname):
|
|
file = filename[:-3] + _suffix
|
|
t_py = long(finfo[8])
|
|
t_pyc = _timestamp(file)
|
|
|
|
code = None
|
|
if t_pyc is not None and t_pyc >= t_py:
|
|
f = open(file, 'rb')
|
|
if f.read(4) == imp.get_magic():
|
|
t = struct.unpack('<I', f.read(4))[0]
|
|
if t == t_py:
|
|
code = marshal.load(f)
|
|
f.close()
|
|
if code is None:
|
|
file = filename
|
|
code = _compile(file, t_py)
|
|
|
|
return 0, code, { '__file__' : file }
|
|
|
|
class DynLoadSuffixImporter:
|
|
def __init__(self, desc):
|
|
self.desc = desc
|
|
|
|
def import_file(self, filename, finfo, fqname):
|
|
fp = open(filename, self.desc[1])
|
|
module = imp.load_module(fqname, fp, filename, self.desc)
|
|
module.__file__ = filename
|
|
return 0, module, { }
|
|
|
|
|
|
######################################################################
|
|
|
|
def _print_importers():
|
|
items = sys.modules.items()
|
|
items.sort()
|
|
for name, module in items:
|
|
if module:
|
|
print name, module.__dict__.get('__importer__', '-- no importer')
|
|
else:
|
|
print name, '-- non-existent module'
|
|
|
|
def _test_revamp():
|
|
ImportManager().install()
|
|
sys.path.insert(0, BuiltinImporter())
|
|
|
|
######################################################################
|
|
|
|
#
|
|
# TODO
|
|
#
|
|
# from Finn Bock:
|
|
# remove use of "strop" -- not available in JPython
|
|
# type(sys) is not a module in JPython. what to use instead?
|
|
# imp.C_EXTENSION is not in JPython. same for get_suffixes and new_module
|
|
#
|
|
# given foo.py of:
|
|
# import sys
|
|
# sys.modules['foo'] = sys
|
|
#
|
|
# ---- standard import mechanism
|
|
# >>> import foo
|
|
# >>> foo
|
|
# <module 'sys' (built-in)>
|
|
#
|
|
# ---- revamped import mechanism
|
|
# >>> import imputil
|
|
# >>> imputil._test_revamp()
|
|
# >>> import foo
|
|
# >>> foo
|
|
# <module 'foo' from 'foo.py'>
|
|
#
|
|
#
|
|
# from MAL:
|
|
# should BuiltinImporter exist in sys.path or hard-wired in ImportManager?
|
|
# need __path__ processing
|
|
# performance
|
|
# move chaining to a subclass [gjs: it's been nuked]
|
|
# avoid strop
|
|
# deinstall should be possible
|
|
# query mechanism needed: is a specific Importer installed?
|
|
# py/pyc/pyo piping hooks to filter/process these files
|
|
# wish list:
|
|
# distutils importer hooked to list of standard Internet repositories
|
|
# module->file location mapper to speed FS-based imports
|
|
# relative imports
|
|
# keep chaining so that it can play nice with other import hooks
|
|
#
|
|
# from Gordon:
|
|
# push MAL's mapper into sys.path[0] as a cache (hard-coded for apps)
|
|
#
|
|
# from Guido:
|
|
# need to change sys.* references for rexec environs
|
|
# need hook for MAL's walk-me-up import strategy, or Tim's absolute strategy
|
|
# watch out for sys.modules[...] == None
|
|
# flag to force absolute imports? (speeds _determine_import_context and
|
|
# checking for a relative module)
|
|
# insert names of archives into sys.path (see quote below)
|
|
# note: reload does NOT blast module dict
|
|
# shift import mechanisms and policies around; provide for hooks, overrides
|
|
# (see quote below)
|
|
# add get_source stuff
|
|
# get_topcode and get_subcode
|
|
# CRLF handling in _compile
|
|
# race condition in _compile
|
|
# refactoring of os.py to deal with _os_bootstrap problem
|
|
# any special handling to do for importing a module with a SyntaxError?
|
|
# (e.g. clean up the traceback)
|
|
# implement "domain" for path-type functionality using pkg namespace
|
|
# (rather than FS-names like __path__)
|
|
# don't use the word "private"... maybe "internal"
|
|
#
|
|
#
|
|
# Guido's comments on sys.path caching:
|
|
#
|
|
# We could cache this in a dictionary: the ImportManager can have a
|
|
# cache dict mapping pathnames to importer objects, and a separate
|
|
# method for coming up with an importer given a pathname that's not yet
|
|
# in the cache. The method should do a stat and/or look at the
|
|
# extension to decide which importer class to use; you can register new
|
|
# importer classes by registering a suffix or a Boolean function, plus a
|
|
# class. If you register a new importer class, the cache is zapped.
|
|
# The cache is independent from sys.path (but maintained per
|
|
# ImportManager instance) so that rearrangements of sys.path do the
|
|
# right thing. If a path is dropped from sys.path the corresponding
|
|
# cache entry is simply no longer used.
|
|
#
|
|
# My/Guido's comments on factoring ImportManager and Importer:
|
|
#
|
|
# > However, we still have a tension occurring here:
|
|
# >
|
|
# > 1) implementing policy in ImportManager assists in single-point policy
|
|
# > changes for app/rexec situations
|
|
# > 2) implementing policy in Importer assists in package-private policy
|
|
# > changes for normal, operating conditions
|
|
# >
|
|
# > I'll see if I can sort out a way to do this. Maybe the Importer class will
|
|
# > implement the methods (which can be overridden to change policy) by
|
|
# > delegating to ImportManager.
|
|
#
|
|
# Maybe also think about what kind of policies an Importer would be
|
|
# likely to want to change. I have a feeling that a lot of the code
|
|
# there is actually not so much policy but a *necessity* to get things
|
|
# working given the calling conventions for the __import__ hook: whether
|
|
# to return the head or tail of a dotted name, or when to do the "finish
|
|
# fromlist" stuff.
|
|
#
|