diff options
Diffstat (limited to 'Lib/runpy.py')
| -rwxr-xr-x | Lib/runpy.py | 431 |
1 files changed, 431 insertions, 0 deletions
diff --git a/Lib/runpy.py b/Lib/runpy.py new file mode 100755 index 0000000..afb0098 --- /dev/null +++ b/Lib/runpy.py @@ -0,0 +1,431 @@ +"""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 + +__all__ = [ + "run_module", +] + +try: + _get_loader = imp.get_loader +except AttributeError: + # get_loader() is not provided by the imp module, so emulate it + # as best we can using the PEP 302 import machinery exposed since + # Python 2.3. The emulation isn't perfect, but the differences + # in the way names are shadowed shouldn't matter in practice. + import os.path + import marshal # Handle compiled Python files + + # This helper is needed in order for the PEP 302 emulation to + # correctly handle compiled files + def _read_compiled_file(compiled_file): + magic = compiled_file.read(4) + if magic != imp.get_magic(): + return None + try: + compiled_file.read(4) # Skip timestamp + return marshal.load(compiled_file) + except Exception: + return None + + class _AbsoluteImporter(object): + """PEP 302 importer wrapper for top level import machinery""" + def find_module(self, mod_name, path=None): + if path is not None: + return None + try: + file, filename, mod_info = imp.find_module(mod_name) + except ImportError: + return None + suffix, mode, mod_type = mod_info + if mod_type == imp.PY_SOURCE: + loader = _SourceFileLoader(mod_name, file, + filename, mod_info) + elif mod_type == imp.PY_COMPILED: + loader = _CompiledFileLoader(mod_name, file, + filename, mod_info) + elif mod_type == imp.PKG_DIRECTORY: + loader = _PackageDirLoader(mod_name, file, + filename, mod_info) + elif mod_type == imp.C_EXTENSION: + loader = _FileSystemLoader(mod_name, file, + filename, mod_info) + else: + loader = _BasicLoader(mod_name, file, + filename, mod_info) + return loader + + + class _FileSystemImporter(object): + """PEP 302 importer wrapper for filesystem based imports""" + def __init__(self, path_item=None): + if path_item is not None: + if path_item != '' and not os.path.isdir(path_item): + raise ImportError("%s is not a directory" % path_item) + self.path_dir = path_item + else: + raise ImportError("Filesystem importer requires " + "a directory name") + + def find_module(self, mod_name, path=None): + if path is not None: + return None + path_dir = self.path_dir + if path_dir == '': + path_dir = os.getcwd() + sub_name = mod_name.rsplit(".", 1)[-1] + try: + file, filename, mod_info = imp.find_module(sub_name, + [path_dir]) + except ImportError: + return None + if not filename.startswith(path_dir): + return None + suffix, mode, mod_type = mod_info + if mod_type == imp.PY_SOURCE: + loader = _SourceFileLoader(mod_name, file, + filename, mod_info) + elif mod_type == imp.PY_COMPILED: + loader = _CompiledFileLoader(mod_name, file, + filename, mod_info) + elif mod_type == imp.PKG_DIRECTORY: + loader = _PackageDirLoader(mod_name, file, + filename, mod_info) + elif mod_type == imp.C_EXTENSION: + loader = _FileSystemLoader(mod_name, file, + filename, mod_info) + else: + loader = _BasicLoader(mod_name, file, + filename, mod_info) + return loader + + + class _BasicLoader(object): + """PEP 302 loader wrapper for top level import machinery""" + def __init__(self, mod_name, file, filename, mod_info): + self.mod_name = mod_name + self.file = file + self.filename = filename + self.mod_info = mod_info + + def _fix_name(self, mod_name): + if mod_name is None: + mod_name = self.mod_name + elif mod_name != self.mod_name: + raise ImportError("Loader for module %s cannot handle " + "module %s" % (self.mod_name, mod_name)) + return mod_name + + def load_module(self, mod_name=None): + mod_name = self._fix_name(mod_name) + mod = imp.load_module(mod_name, self.file, + self.filename, self.mod_info) + mod.__loader__ = self # for introspection + return mod + + def get_code(self, mod_name=None): + return None + + def get_source(self, mod_name=None): + return None + + def is_package(self, mod_name=None): + return False + + def close(self): + if self.file: + self.file.close() + + def __del__(self): + self.close() + + + class _FileSystemLoader(_BasicLoader): + """PEP 302 loader wrapper for filesystem based imports""" + def get_code(self, mod_name=None): + mod_name = self._fix_name(mod_name) + return self._get_code(mod_name) + + def get_data(self, pathname): + return open(pathname, "rb").read() + + def get_filename(self, mod_name=None): + mod_name = self._fix_name(mod_name) + return self._get_filename(mod_name) + + def get_source(self, mod_name=None): + mod_name = self._fix_name(mod_name) + return self._get_source(mod_name) + + def is_package(self, mod_name=None): + mod_name = self._fix_name(mod_name) + return self._is_package(mod_name) + + def _get_code(self, mod_name): + return None + + def _get_filename(self, mod_name): + return self.filename + + def _get_source(self, mod_name): + return None + + def _is_package(self, mod_name): + return False + + class _PackageDirLoader(_FileSystemLoader): + """PEP 302 loader wrapper for PKG_DIRECTORY directories""" + def _is_package(self, mod_name): + return True + + + class _SourceFileLoader(_FileSystemLoader): + """PEP 302 loader wrapper for PY_SOURCE modules""" + def _get_code(self, mod_name): + return compile(self._get_source(mod_name), + self.filename, 'exec') + + def _get_source(self, mod_name): + f = self.file + f.seek(0) + return f.read() + + + class _CompiledFileLoader(_FileSystemLoader): + """PEP 302 loader wrapper for PY_COMPILED modules""" + def _get_code(self, mod_name): + f = self.file + f.seek(0) + return _read_compiled_file(f) + + + def _get_importer(path_item): + """Retrieve a PEP 302 importer for the given path item + + The returned importer is cached in sys.path_importer_cache + if it was newly created by a path hook. + + If there is no importer, a wrapper around the basic import + machinery is returned. This wrapper is never inserted into + the importer cache (None is inserted instead). + + The cache (or part of it) can be cleared manually if a + rescan of sys.path_hooks is necessary. + """ + try: + importer = sys.path_importer_cache[path_item] + except KeyError: + for path_hook in sys.path_hooks: + try: + importer = path_hook(path_item) + break + except ImportError: + pass + else: + importer = None + sys.path_importer_cache[path_item] = importer + if importer is None: + try: + importer = _FileSystemImporter(path_item) + except ImportError: + pass + return importer + + + def _get_path_loader(mod_name, path=None): + """Retrieve a PEP 302 loader using a path importer""" + if path is None: + path = sys.path + absolute_loader = _AbsoluteImporter().find_module(mod_name) + if isinstance(absolute_loader, _FileSystemLoader): + # Found in filesystem, so scan path hooks + # before accepting this one as the right one + loader = None + else: + # Not found in filesystem, so use top-level loader + loader = absolute_loader + else: + loader = absolute_loader = None + if loader is None: + for path_item in path: + importer = _get_importer(path_item) + if importer is not None: + loader = importer.find_module(mod_name) + if loader is not None: + # Found a loader for our module + break + else: + # No path hook found, so accept the top level loader + loader = absolute_loader + return loader + + def _get_package(pkg_name): + """Retrieve a named package""" + pkg = __import__(pkg_name) + sub_pkg_names = pkg_name.split(".") + for sub_pkg in sub_pkg_names[1:]: + pkg = getattr(pkg, sub_pkg) + return pkg + + def _get_loader(mod_name, path=None): + """Retrieve a PEP 302 loader for the given module or package + + If the module or package is accessible via the normal import + mechanism, a wrapper around the relevant part of that machinery + is returned. + + Non PEP 302 mechanisms (e.g. the Windows registry) used by the + standard import machinery to find files in alternative locations + are partially supported, but are searched AFTER sys.path. Normally, + these locations are searched BEFORE sys.path, preventing sys.path + entries from shadowing them. + For this to cause a visible difference in behaviour, there must + be a module or package name that is accessible via both sys.path + and one of the non PEP 302 file system mechanisms. In this case, + the emulation will find the former version, while the builtin + import mechanism will find the latter. + Items of the following types can be affected by this discrepancy: + imp.C_EXTENSION + imp.PY_SOURCE + imp.PY_COMPILED + imp.PKG_DIRECTORY + """ + try: + loader = sys.modules[mod_name].__loader__ + except (KeyError, AttributeError): + loader = None + if loader is None: + imp.acquire_lock() + try: + # Module not in sys.modules, or uses an unhooked loader + parts = mod_name.rsplit(".", 1) + if len(parts) == 2: + # Sub package, so use parent package's path + pkg_name, sub_name = parts + if pkg_name and pkg_name[0] != '.': + if path is not None: + raise ImportError("Path argument must be None " + "for a dotted module name") + pkg = _get_package(pkg_name) + try: + path = pkg.__path__ + except AttributeError: + raise ImportError(pkg_name + + " is not a package") + else: + raise ImportError("Relative import syntax is not " + "supported by _get_loader()") + else: + # Top level module, so stick with default path + sub_name = mod_name + + for importer in sys.meta_path: + loader = importer.find_module(mod_name, path) + if loader is not None: + # Found a metahook to handle the module + break + else: + # Handling via the standard path mechanism + loader = _get_path_loader(mod_name, path) + finally: + imp.release_lock() + return loader + + +# This helper is needed due to a missing component in the PEP 302 +# loader protocol (specifically, "get_filename" is non-standard) +def _get_filename(loader, mod_name): + try: + get_filename = loader.get_filename + except AttributeError: + return None + else: + return get_filename(mod_name) + +# ------------------------------------------------------------ +# Done with the import machinery emulation, on with the code! + +def _run_code(code, run_globals, init_globals, + mod_name, mod_fname, mod_loader): + """Helper for _run_module_code""" + if init_globals is not None: + run_globals.update(init_globals) + run_globals.update(__name__ = mod_name, + __file__ = mod_fname, + __loader__ = mod_loader) + 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, alter_sys=False): + """Helper for run_module""" + # Set up the top level namespace dictionary + if alter_sys: + # Modify sys.argv[0] and sys.module[mod_name] + temp_module = imp.new_module(mod_name) + mod_globals = temp_module.__dict__ + saved_argv0 = sys.argv[0] + restore_module = mod_name in sys.modules + if restore_module: + saved_module = sys.modules[mod_name] + imp.acquire_lock() + try: + sys.argv[0] = mod_fname + sys.modules[mod_name] = temp_module + try: + _run_code(code, mod_globals, init_globals, + mod_name, mod_fname, mod_loader) + finally: + sys.argv[0] = saved_argv0 + if restore_module: + sys.modules[mod_name] = saved_module + else: + del sys.modules[mod_name] + finally: + imp.release_lock() + # Copy the globals of the temporary module, as they + # may be cleared when the temporary module goes away + return mod_globals.copy() + else: + # Leave the sys module alone + return _run_code(code, {}, init_globals, + mod_name, mod_fname, mod_loader) + + +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 + """ + loader = _get_loader(mod_name) + if loader is None: + raise ImportError("No module named " + mod_name) + code = loader.get_code(mod_name) + if code is None: + raise ImportError("No code object available for " + mod_name) + filename = _get_filename(loader, mod_name) + if run_name is None: + run_name = mod_name + return _run_module_code(code, init_globals, run_name, + filename, loader, alter_sys) + + +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(sys.argv[0], run_name="__main__", alter_sys=True) |