"""Utilities to support packages.""" from collections import namedtuple from functools import singledispatch as simplegeneric import importlib import importlib.util import importlib.machinery import os import os.path import re import sys from types import ModuleType import warnings __all__ = [ 'get_importer', 'iter_importers', 'get_loader', 'find_loader', 'walk_packages', 'iter_modules', 'get_data', 'ImpImporter', 'ImpLoader', 'read_code', 'extend_path', 'ModuleInfo', ] ModuleInfo = namedtuple('ModuleInfo', 'module_finder name ispkg') ModuleInfo.__doc__ = 'A namedtuple with minimal info about a module.' def _get_spec(finder, name): """Return the finder-specific module spec.""" # Works with legacy finders. try: find_spec = finder.find_spec except AttributeError: loader = finder.find_module(name) if loader is None: return None return importlib.util.spec_from_loader(name, loader) else: return find_spec(name) def read_code(stream): # This helper is needed in order for the PEP 302 emulation to # correctly handle compiled files import marshal magic = stream.read(4) if magic != importlib.util.MAGIC_NUMBER: return None stream.read(12) # Skip rest of the header return marshal.load(stream) def walk_packages(path=None, prefix='', onerror=None): """Yields ModuleInfo for all modules recursively on path, or, if path is None, all accessible modules. 'path' should be either None or a list of paths to look for modules in. 'prefix' is a string to output on the front of every module name on output. Note that this function must import all *packages* (NOT all modules!) on the given path, in order to access the __path__ attribute to find submodules. 'onerror' is a function which gets called with one argument (the name of the package which was being imported) if any exception occurs while trying to import a package. If no onerror function is supplied, ImportErrors are caught and ignored, while all other exceptions are propagated, terminating the search. Examples: # list all modules python can access walk_packages() # list all submodules of ctypes walk_packages(ctypes.__path__, ctypes.__name__+'.') """ def seen(p, m={}): if p in m: return True m[p] = True for info in iter_modules(path, prefix): yield info if info.ispkg: try: __import__(info.name) except ImportError: if onerror is not None: onerror(info.name) except Exception: if onerror is not None: onerror(info.name) else: raise else: path = getattr(sys.modules[info.name], '__path__', None) or [] # don't traverse path items we've seen before path = [p for p in path if not seen(p)] yield from walk_packages(path, info.name+'.', onerror) def iter_modules(path=None, prefix=''): """Yields ModuleInfo for all submodules on path, or, if path is None, all top-level modules on sys.path. 'path' should be either None or a list of paths to look for modules in. 'prefix' is a string to output on the front of every module name on output. """ if path is None: importers = iter_importers() elif isinstance(path, str): raise ValueError("path must be None or list of paths to look for " "modules in") else: importers = map(get_importer, path) yielded = {} for i in importers: for name, ispkg in iter_importer_modules(i, prefix): if name not in yielded: yielded[name] = 1 yield ModuleInfo(i, name, ispkg) @simplegeneric def iter_importer_modules(importer, prefix=''): if not hasattr(importer, 'iter_modules'): return [] return importer.iter_modules(prefix) # Implement a file walker for the normal importlib path hook def _iter_file_finder_modules(importer, prefix=''): if importer.path is None or not os.path.isdir(importer.path): return yielded = {} import inspect try: filenames = os.listdir(importer.path) except OSError: # ignore unreadable directories like import does filenames = [] filenames.sort() # handle packages before same-named modules for fn in filenames: modname = inspect.getmodulename(fn) if modname=='__init__' or modname in yielded: continue path = os.path.join(importer.path, fn) ispkg = False if not modname and os.path.isdir(path) and '.' not in fn: modname = fn try: dircontents = os.listdir(path) except OSError: # ignore unreadable directories like import does dircontents = [] for fn in dircontents: subname = inspect.getmodulename(fn) if subname=='__init__': ispkg = True break else: continue # not a package if modname and '.' not in modname: yielded[modname] = 1 yield prefix + modname, ispkg iter_importer_modules.register( importlib.machinery.FileFinder, _iter_file_finder_modules) def _import_imp(): global imp with warnings.catch_warnings(): warnings.simplefilter('ignore', DeprecationWarning) imp = importlib.import_module('imp') class ImpImporter: """PEP 302 Finder that wraps Python's "classic" import algorithm ImpImporter(dirname) produces a PEP 302 finder that searches that directory. ImpImporter(None) produces a PEP 302 finder that searches the current sys.path, plus any modules that are frozen or built-in. Note that ImpImporter does not currently support being used by placement on sys.meta_path. """ def __init__(self, path=None): global imp warnings.warn("This emulation is deprecated, use 'importlib' instead", DeprecationWarning) _import_imp() self.path = path def find_module(self, fullname, path=None): # Note: we ignore 'path' argument since it is only used via meta_path subname = fullname.split(".")[-1] if subname != fullname and self.path is None: return None if self.path is None: path = None else: path = [os.path.realpath(self.path)] try: file, filename, etc = imp.find_module(subname, path) except ImportError: return None return ImpLoader(fullname, file, filename, etc) def iter_modules(self, prefix=''): if self.path is None or not os.path.isdir(self.path): return yielded = {} import inspect try: filenames = os.listdir(self.path) except OSError: # ignore unreadable directories like import does filenames = [] filenames.sort() # handle packages before same-named modules for fn in filenames: modname = inspect.getmodulename(fn) if modname=='__init__' or modname in yielded: continue path = os.path.join(self.path, fn) ispkg = False if not modname and os.path.isdir(path) and '.' not in fn: modname = fn try: dircontents = os.listdir(path) except OSError: # ignore unreadable directories like import does dircontents = [] for fn in dircontents: subname = inspect.getmodulename(fn) if subname=='__init__': ispkg = True break else: continue # not a package if modname and '.' not in modname: yielded[modname] = 1 yield prefix + modname, ispkg class ImpLoader: """PEP 302 Loader that wraps Python's "classic" import algorithm """ code = source = None def __init__(self, fullname, file, filename, etc): warnings.warn("This emulation is deprecated, use 'importlib' instead", DeprecationWarning) _import_imp() self.file = file self.filename = filename self.fullname = fullname self.etc = etc def load_module(self, fullname): self._reopen() try: mod = imp.load_module(fullname, self.file, self.filename, self.etc) finally: if self.file: self.file.close() # Note: we don't set __loader__ because we want the module to look # normal; i.e. this is just a wrapper for standard import machinery return mod def get_data(self, pathname): with open(pathname, "rb") as file: return file.read() def _reopen(self): if self.file and self.file.closed: mod_type = self.etc[2] if mod_type==imp.PY_SOURCE: self.file = open(self.filename, 'r') elif mod_type in (imp.PY_COMPILED, imp.C_EXTENSION): self.file = open(self.filename, 'rb') def _fix_name(self, fullname): if fullname is None: fullname = self.fullname elif fullname != self.fullname: raise ImportError("Loader for module %s cannot handle " "module %s" % (self.fullname, fullname)) return fullname def is_package(self, fullname): fullname = self._fix_name(fullname) return self.etc[2]==imp.PKG_DIRECTORY def get_code(self, fullname=None): fullname = self._fix_name(fullname) if self.code is None: mod_type = self.etc[2] if mod_type==imp.PY_SOURCE: source = self.get_source(fullname) self.code = compile(source, self.filename, 'exec') elif mod_type==imp.PY_COMPILED: self._reopen() try: self.code = read_code(self.file) finally: self.file.close() elif mod_type==imp.PKG_DIRECTORY: self.code = self._get_delegate().get_code() return self.code def get_source(self, fullname=None): fullname = self._fix_name(fullname) if self.source is None: mod_type = self.etc[2] if mod_type==imp.PY_SOURCE: self._reopen() try: self.source = self.file.read() finally: self.file.close() elif mod_type==imp.PY_COMPILED: if os.path.exists(self.filename[:-1]): with open(self.filename[:-1], 'r') as f: self.source = f.read() elif mod_type==imp.PKG_DIRECTORY: self.source = self._get_delegate().get_source() return self.source def _get_delegate(self): finder = ImpImporter(self.filename) spec = _get_spec(finder, '__init__') return spec.loader def get_filename(self, fullname=None): fullname = self._fix_name(fullname) mod_type = self.etc[2] if mod_type==imp.PKG_DIRECTORY: return self._get_delegate().get_filename() elif mod_type in (imp.PY_SOURCE, imp.PY_COMPILED, imp.C_EXTENSION): return self.filename return None try: import zipimport from zipimport import zipimporter def iter_zipimport_modules(importer, prefix=''): dirlist = sorted(zipimport._zip_directory_cache[importer.archive]) _prefix = importer.prefix plen = len(_prefix) yielded = {} import inspect for fn in dirlist: if not fn.startswith(_prefix): continue fn = fn[plen:].split(os.sep) if len(fn)==2 and fn[1].startswith('__init__.py'): if fn[0] not in yielded: yielded[fn[0]] = 1 yield prefix + fn[0], True if len(fn)!=1: continue modname = inspect.getmodulename(fn[0]) if modname=='__init__': continue if modname and '.' not in modname and modname not in yielded: yielded[modname] = 1 yield prefix + modname, False iter_importer_modules.register(zipimporter, iter_zipimport_modules) except ImportError: pass def get_importer(path_item): """Retrieve a finder for the given path item The returned finder is cached in sys.path_importer_cache if it was newly created by a path hook. 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) sys.path_importer_cache.setdefault(path_item, importer) break except ImportError: pass else: importer = None return importer def iter_importers(fullname=""): """Yield finders for the given module name If fullname contains a '.', the finders will be for the package containing fullname, otherwise they will be all registered top level finders (i.e. those on both sys.meta_path and sys.path_hooks). If the named module is in a package, that package is imported as a side effect of invoking this function. If no module name is specified, all top level finders are produced. """ if fullname.startswith('.'): msg = "Relative module name {!r} not supported".format(fullname) raise ImportError(msg) if '.' in fullname: # Get the containing package's __path__ pkg_name = fullname.rpartition(".")[0] pkg = importlib.import_module(pkg_name) path = getattr(pkg, '__path__', None) if path is None: return else: yield from sys.meta_path path = sys.path for item in path: yield get_importer(item) def get_loader(module_or_name): """Get a "loader" object for module_or_name Returns None if the module cannot be found or imported. If the named module is not already imported, its containing package (if any) is imported, in order to establish the package __path__. """ if module_or_name in sys.modules: module_or_name = sys.modules[module_or_name] if module_or_name is None: return None if isinstance(module_or_name, ModuleType): module = module_or_name loader = getattr(module, '__loader__', None) if loader is not None: return loader if getattr(module, '__spec__', None) is None: return None fullname = module.__name__ else: fullname = module_or_name return find_loader(fullname) def find_loader(fullname): """Find a "loader" object for fullname This is a backwards compatibility wrapper around importlib.util.find_spec that converts most failures to ImportError and only returns the loader rather than the full spec """ if fullname.startswith('.'): msg = "Relative module name {!r} not supported".format(fullname) raise ImportError(msg) try: spec = importlib.util.find_spec(fullname) except (ImportError, AttributeError, TypeError, ValueError) as ex: # This hack fixes an impedance mismatch between pkgutil and # importlib, where the latter raises other errors for cases where # pkgutil previously raised ImportError msg = "Error while finding loader for {!r} ({}: {})" raise ImportError(msg.format(fullname, type(ex), ex)) from ex return spec.loader if spec is not None else None def extend_path(path, name): """Extend a package's path. Intended use is to place the following code in a package's __init__.py: from pkgutil import extend_path __path__ = extend_path(__path__, __name__) This will add to the package's __path__ all subdirectories of directories on sys.path named after the package. This is useful if one wants to distribute different parts of a single logical package as multiple directories. It also looks for *.pkg files beginning where * matches the name argument. This feature is similar to *.pth files (see site.py), except that it doesn't special-case lines starting with 'import'. A *.pkg file is trusted at face value: apart from checking for duplicates, all entries found in a *.pkg file are added to the path, regardless of whether they are exist the filesystem. (This is a feature.) If the input path is not a list (as is the case for frozen packages) it is returned unchanged. The input path is not modified; an extended copy is returned. Items are only appended to the copy at the end. It is assumed that sys.path is a sequence. Items of sys.path that are not (unicode or 8-bit) strings referring to existing directories are ignored. Unicode items of sys.path that cause errors when used as filenames may cause this function to raise an exception (in line with os.path.isdir() behavior). """ if not isinstance(path, list): # This could happen e.g. when this is called from inside a # frozen package. Return the path unchanged in that case. return path sname_pkg = name + ".pkg" path = path[:] # Start with a copy of the existing path parent_package, _, final_name = name.rpartition('.') if parent_package: try: search_path = sys.modules[parent_package].__path__ except (KeyError, AttributeError): # We can't do anything: find_loader() returns None when # passed a dotted name. return path else: search_path = sys.path for dir in search_path: if not isinstance(dir, str): continue finder = get_importer(dir) if finder is not None: portions = [] if hasattr(finder, 'find_spec'): spec = finder.find_spec(final_name) if spec is not None: portions = spec.submodule_search_locations or [] # Is this finder PEP 420 compliant? elif hasattr(finder, 'find_loader'): _, portions = finder.find_loader(final_name) for portion in portions: # XXX This may still add duplicate entries to path on # case-insensitive filesystems if portion not in path: path.append(portion) # XXX Is this the right thing for subpackages like zope.app? # It looks for a file named "zope.app.pkg" pkgfile = os.path.join(dir, sname_pkg) if os.path.isfile(pkgfile): try: f = open(pkgfile) except OSError as msg: sys.stderr.write("Can't open %s: %s\n" % (pkgfile, msg)) else: with f: for line in f: line = line.rstrip('\n') if not line or line.startswith('#'): continue path.append(line) # Don't check for existence! return path def get_data(package, resource): """Get a resource from a package. This is a wrapper round the PEP 302 loader get_data API. The package argument should be the name of a package, in standard module format (foo.bar). The resource argument should be in the form of a relative filename, using '/' as the path separator. The parent directory name '..' is not allowed, and nor is a rooted name (starting with a '/'). The function returns a binary string, which is the contents of the specified resource. For packages located in the filesystem, which have already been imported, this is the rough equivalent of d = os.path.dirname(sys.modules[package].__file__) data = open(os.path.join(d, resource), 'rb').read() If the package cannot be located or loaded, or it uses a PEP 302 loader which does not support get_data(), then None is returned. """ spec = importlib.util.find_spec(package) if spec is None: return None loader = spec.loader if loader is None or not hasattr(loader, 'get_data'): return None # XXX needs test mod = (sys.modules.get(package) or importlib._bootstrap._load(spec)) if mod is None or not hasattr(mod, '__file__'): return None # Modify the resource name to be compatible with the loader.get_data # signature - an os.path format "filename" starting with the dirname of # the package's __file__ parts = resource.split('/') parts.insert(0, os.path.dirname(mod.__file__)) resource_name = os.path.join(*parts) return loader.get_data(resource_name) _DOTTED_WORDS = r'(?!\d)(\w+)(\.(?!\d)(\w+))*' _NAME_PATTERN = re.compile(f'^(?P<pkg>{_DOTTED_WORDS})(?P<cln>:(?P<obj>{_DOTTED_WORDS})?)?$', re.U) del _DOTTED_WORDS def resolve_name(name): """ Resolve a name to an object. It is expected that `name` will be a string in one of the following formats, where W is shorthand for a valid Python identifier and dot stands for a literal period in these pseudo-regexes: W(.W)* W(.W)*:(W(.W)*)? The first form is intended for backward compatibility only. It assumes that some part of the dotted name is a package, and the rest is an object somewhere within that package, possibly nested inside other objects. Because the place where the package stops and the object hierarchy starts can't be inferred by inspection, repeated attempts to import must be done with this form. In the second form, the caller makes the division point clear through the provision of a single colon: the dotted name to the left of the colon is a package to be imported, and the dotted name to the right is the object hierarchy within that package. Only one import is needed in this form. If it ends with the colon, then a module object is returned. The function will return an object (which might be a module), or raise one of the following exceptions: ValueError - if `name` isn't in a recognised format ImportError - if an import failed when it shouldn't have AttributeError - if a failure occurred when traversing the object hierarchy within the imported package to get to the desired object) """ m = _NAME_PATTERN.match(name) if not m: raise ValueError(f'invalid format: {name!r}') gd = m.groupdict() if gd.get('cln'): # there is a colon - a one-step import is all that's needed mod = importlib.import_module(gd['pkg']) parts = gd.get('obj') parts = parts.split('.') if parts else [] else: # no colon - have to iterate to find the package boundary parts = name.split('.') modname = parts.pop(0) # first part *must* be a module/package. mod = importlib.import_module(modname) while parts: p = parts[0] s = f'{modname}.{p}' try: mod = importlib.import_module(s) parts.pop(0) modname = s except ImportError: break # if we reach this point, mod is the module, already imported, and # parts is the list of parts in the object hierarchy to be traversed, or # an empty list if just the module is wanted. result = mod for p in parts: result = getattr(result, p) return result