diff options
Diffstat (limited to 'lib/python2.7/runpy.py')
| -rw-r--r-- | lib/python2.7/runpy.py | 278 |
1 files changed, 278 insertions, 0 deletions
diff --git a/lib/python2.7/runpy.py b/lib/python2.7/runpy.py new file mode 100644 index 0000000..c4d7cc2 --- /dev/null +++ b/lib/python2.7/runpy.py @@ -0,0 +1,278 @@ +"""runpy.py - locating and running Python code using the module namespace + +Provides support for locating and running Python scripts using the Python +module namespace instead of the native filesystem. + +This allows Python code to play nicely with non-filesystem based PEP 302 +importers when locating support scripts as well as when importing modules. +""" +# Written by Nick Coghlan <ncoghlan at gmail.com> +# to implement PEP 338 (Executing Modules as Scripts) + +import sys +import imp +from pkgutil import read_code +try: + from imp import get_loader +except ImportError: + from pkgutil import get_loader + +__all__ = [ + "run_module", "run_path", +] + +class _TempModule(object): + """Temporarily replace a module in sys.modules with an empty namespace""" + def __init__(self, mod_name): + self.mod_name = mod_name + self.module = imp.new_module(mod_name) + self._saved_module = [] + + def __enter__(self): + mod_name = self.mod_name + try: + self._saved_module.append(sys.modules[mod_name]) + except KeyError: + pass + sys.modules[mod_name] = self.module + return self + + def __exit__(self, *args): + if self._saved_module: + sys.modules[self.mod_name] = self._saved_module[0] + else: + del sys.modules[self.mod_name] + self._saved_module = [] + +class _ModifiedArgv0(object): + def __init__(self, value): + self.value = value + self._saved_value = self._sentinel = object() + + def __enter__(self): + if self._saved_value is not self._sentinel: + raise RuntimeError("Already preserving saved value") + self._saved_value = sys.argv[0] + sys.argv[0] = self.value + + def __exit__(self, *args): + self.value = self._sentinel + sys.argv[0] = self._saved_value + +def _run_code(code, run_globals, init_globals=None, + mod_name=None, mod_fname=None, + mod_loader=None, pkg_name=None): + """Helper to run code in nominated namespace""" + if init_globals is not None: + run_globals.update(init_globals) + run_globals.update(__name__ = mod_name, + __file__ = mod_fname, + __loader__ = mod_loader, + __package__ = pkg_name) + exec code in run_globals + return run_globals + +def _run_module_code(code, init_globals=None, + mod_name=None, mod_fname=None, + mod_loader=None, pkg_name=None): + """Helper to run code in new namespace with sys modified""" + with _TempModule(mod_name) as temp_module, _ModifiedArgv0(mod_fname): + mod_globals = temp_module.module.__dict__ + _run_code(code, mod_globals, init_globals, + mod_name, mod_fname, mod_loader, pkg_name) + # Copy the globals of the temporary module, as they + # may be cleared when the temporary module goes away + return mod_globals.copy() + + +# This helper is needed due to a missing component in the PEP 302 +# loader protocol (specifically, "get_filename" is non-standard) +# Since we can't introduce new features in maintenance releases, +# support was added to zipimporter under the name '_get_filename' +def _get_filename(loader, mod_name): + for attr in ("get_filename", "_get_filename"): + meth = getattr(loader, attr, None) + if meth is not None: + return meth(mod_name) + return None + +# Helper to get the loader, code and filename for a module +def _get_module_details(mod_name): + loader = get_loader(mod_name) + if loader is None: + raise ImportError("No module named %s" % mod_name) + if loader.is_package(mod_name): + if mod_name == "__main__" or mod_name.endswith(".__main__"): + raise ImportError("Cannot use package as __main__ module") + try: + pkg_main_name = mod_name + ".__main__" + return _get_module_details(pkg_main_name) + except ImportError, e: + raise ImportError(("%s; %r is a package and cannot " + + "be directly executed") %(e, mod_name)) + code = loader.get_code(mod_name) + if code is None: + raise ImportError("No code object available for %s" % mod_name) + filename = _get_filename(loader, mod_name) + return mod_name, loader, code, filename + + +def _get_main_module_details(): + # Helper that gives a nicer error message when attempting to + # execute a zipfile or directory by invoking __main__.py + main_name = "__main__" + try: + return _get_module_details(main_name) + except ImportError as exc: + if main_name in str(exc): + raise ImportError("can't find %r module in %r" % + (main_name, sys.path[0])) + raise + +# This function is the actual implementation of the -m switch and direct +# execution of zipfiles and directories and is deliberately kept private. +# This avoids a repeat of the situation where run_module() no longer met the +# needs of mainmodule.c, but couldn't be changed because it was public +def _run_module_as_main(mod_name, alter_argv=True): + """Runs the designated module in the __main__ namespace + + Note that the executed module will have full access to the + __main__ namespace. If this is not desirable, the run_module() + function should be used to run the module code in a fresh namespace. + + At the very least, these variables in __main__ will be overwritten: + __name__ + __file__ + __loader__ + __package__ + """ + try: + if alter_argv or mod_name != "__main__": # i.e. -m switch + mod_name, loader, code, fname = _get_module_details(mod_name) + else: # i.e. directory or zipfile execution + mod_name, loader, code, fname = _get_main_module_details() + except ImportError as exc: + msg = "%s: %s" % (sys.executable, str(exc)) + sys.exit(msg) + pkg_name = mod_name.rpartition('.')[0] + main_globals = sys.modules["__main__"].__dict__ + if alter_argv: + sys.argv[0] = fname + return _run_code(code, main_globals, None, + "__main__", fname, loader, pkg_name) + +def run_module(mod_name, init_globals=None, + run_name=None, alter_sys=False): + """Execute a module's code without importing it + + Returns the resulting top level namespace dictionary + """ + mod_name, loader, code, fname = _get_module_details(mod_name) + if run_name is None: + run_name = mod_name + pkg_name = mod_name.rpartition('.')[0] + if alter_sys: + return _run_module_code(code, init_globals, run_name, + fname, loader, pkg_name) + else: + # Leave the sys module alone + return _run_code(code, {}, init_globals, run_name, + fname, loader, pkg_name) + + +# XXX (ncoghlan): Perhaps expose the C API function +# as imp.get_importer instead of reimplementing it in Python? +def _get_importer(path_name): + """Python version of PyImport_GetImporter C API function""" + cache = sys.path_importer_cache + try: + importer = cache[path_name] + except KeyError: + # Not yet cached. Flag as using the + # standard machinery until we finish + # checking the hooks + cache[path_name] = None + for hook in sys.path_hooks: + try: + importer = hook(path_name) + break + except ImportError: + pass + else: + # The following check looks a bit odd. The trick is that + # NullImporter raises ImportError if the supplied path is a + # *valid* directory entry (and hence able to be handled + # by the standard import machinery) + try: + importer = imp.NullImporter(path_name) + except ImportError: + return None + cache[path_name] = importer + return importer + +def _get_code_from_file(fname): + # Check for a compiled file first + with open(fname, "rb") as f: + code = read_code(f) + if code is None: + # That didn't work, so try it as normal source code + with open(fname, "rU") as f: + code = compile(f.read(), fname, 'exec') + return code + +def run_path(path_name, init_globals=None, run_name=None): + """Execute code located at the specified filesystem location + + Returns the resulting top level namespace dictionary + + The file path may refer directly to a Python script (i.e. + one that could be directly executed with execfile) or else + it may refer to a zipfile or directory containing a top + level __main__.py script. + """ + if run_name is None: + run_name = "<run_path>" + importer = _get_importer(path_name) + if isinstance(importer, imp.NullImporter): + # Not a valid sys.path entry, so run the code directly + # execfile() doesn't help as we want to allow compiled files + code = _get_code_from_file(path_name) + return _run_module_code(code, init_globals, run_name, path_name) + else: + # Importer is defined for path, so add it to + # the start of sys.path + sys.path.insert(0, path_name) + try: + # Here's where things are a little different from the run_module + # case. There, we only had to replace the module in sys while the + # code was running and doing so was somewhat optional. Here, we + # have no choice and we have to remove it even while we read the + # code. If we don't do this, a __loader__ attribute in the + # existing __main__ module may prevent location of the new module. + main_name = "__main__" + saved_main = sys.modules[main_name] + del sys.modules[main_name] + try: + mod_name, loader, code, fname = _get_main_module_details() + finally: + sys.modules[main_name] = saved_main + pkg_name = "" + with _TempModule(run_name) as temp_module, \ + _ModifiedArgv0(path_name): + mod_globals = temp_module.module.__dict__ + return _run_code(code, mod_globals, init_globals, + run_name, fname, loader, pkg_name).copy() + finally: + try: + sys.path.remove(path_name) + except ValueError: + pass + + +if __name__ == "__main__": + # Run the module specified as the next command line argument + if len(sys.argv) < 2: + print >> sys.stderr, "No module specified for execution" + else: + del sys.argv[0] # Make the requested module sys.argv[0] + _run_module_as_main(sys.argv[0]) |