| """ |
| Import utilities |
| |
| Exported classes: |
| ImportManager Manage the import process |
| |
| Importer Base class for replacing standard import functions |
| BuiltinImporter Emulate the import mechanism for builtin and frozen modules |
| |
| DynLoadSuffixImporter |
| """ |
| from warnings import warnpy3k |
| warnpy3k("the imputil module has been removed in Python 3.0", stacklevel=2) |
| del warnpy3k |
| |
| # note: avoid importing non-builtin modules |
| import imp ### not available in Jython? |
| import sys |
| import __builtin__ |
| |
| # for the DirectoryImporter |
| import struct |
| import marshal |
| |
| __all__ = ["ImportManager","Importer","BuiltinImporter"] |
| |
| _StringType = type('') |
| _ModuleType = type(sys) ### doesn't work in Jython... |
| |
| class ImportManager: |
| "Manage the import process." |
| |
| def install(self, namespace=vars(__builtin__)): |
| "Install this ImportManager into the specified namespace." |
| |
| if isinstance(namespace, _ModuleType): |
| namespace = vars(namespace) |
| |
| # Note: we have no notion of "chaining" |
| |
| # Record the previous import hook, then install our own. |
| self.previous_importer = namespace['__import__'] |
| self.namespace = namespace |
| namespace['__import__'] = self._import_hook |
| |
| ### fix this |
| #namespace['reload'] = self._reload_hook |
| |
| def uninstall(self): |
| "Restore the previous import mechanism." |
| self.namespace['__import__'] = self.previous_importer |
| |
| def add_suffix(self, suffix, importFunc): |
| assert hasattr(importFunc, '__call__') |
| self.fs_imp.add_suffix(suffix, importFunc) |
| |
| ###################################################################### |
| # |
| # PRIVATE METHODS |
| # |
| |
| clsFilesystemImporter = None |
| |
| def __init__(self, fs_imp=None): |
| # we're definitely going to be importing something in the future, |
| # so let's just load the OS-related facilities. |
| if not _os_stat: |
| _os_bootstrap() |
| |
| # This is the Importer that we use for grabbing stuff from the |
| # filesystem. It defines one more method (import_from_dir) for our use. |
| if fs_imp is None: |
| cls = self.clsFilesystemImporter or _FilesystemImporter |
| fs_imp = cls() |
| self.fs_imp = fs_imp |
| |
| # Initialize the set of suffixes that we recognize and import. |
| # The default will import dynamic-load modules first, followed by |
| # .py files (or a .py file's cached bytecode) |
| for desc in imp.get_suffixes(): |
| if desc[2] == imp.C_EXTENSION: |
| self.add_suffix(desc[0], |
| DynLoadSuffixImporter(desc).import_file) |
| self.add_suffix('.py', py_suffix_importer) |
| |
| def _import_hook(self, fqname, globals=None, locals=None, fromlist=None): |
| """Python calls this hook to locate and import a module.""" |
| |
| parts = fqname.split('.') |
| |
| # determine the context of this import |
| parent = self._determine_import_context(globals) |
| |
| # if there is a parent, then its importer should manage this import |
| if parent: |
| module = parent.__importer__._do_import(parent, parts, fromlist) |
| if module: |
| return module |
| |
| # has the top module already been imported? |
| try: |
| top_module = sys.modules[parts[0]] |
| except KeyError: |
| |
| # look for the topmost module |
| top_module = self._import_top_module(parts[0]) |
| if not top_module: |
| # the topmost module wasn't found at all. |
| raise ImportError, 'No module named ' + fqname |
| |
| # fast-path simple imports |
| if len(parts) == 1: |
| if not fromlist: |
| return top_module |
| |
| if not top_module.__dict__.get('__ispkg__'): |
| # __ispkg__ isn't defined (the module was not imported by us), |
| # or it is zero. |
| # |
| # In the former case, there is no way that we could import |
| # sub-modules that occur in the fromlist (but we can't raise an |
| # error because it may just be names) because we don't know how |
| # to deal with packages that were imported by other systems. |
| # |
| # In the latter case (__ispkg__ == 0), there can't be any sub- |
| # modules present, so we can just return. |
| # |
| # In both cases, since len(parts) == 1, the top_module is also |
| # the "bottom" which is the defined return when a fromlist |
| # exists. |
| return top_module |
| |
| importer = top_module.__dict__.get('__importer__') |
| if importer: |
| return importer._finish_import(top_module, parts[1:], fromlist) |
| |
| # Grrr, some people "import os.path" or do "from os.path import ..." |
| if len(parts) == 2 and hasattr(top_module, parts[1]): |
| if fromlist: |
| return getattr(top_module, parts[1]) |
| else: |
| return top_module |
| |
| # If the importer does not exist, then we have to bail. A missing |
| # importer means that something else imported the module, and we have |
| # no knowledge of how to get sub-modules out of the thing. |
| raise ImportError, 'No module named ' + fqname |
| |
| def _determine_import_context(self, globals): |
| """Returns the context in which a module should be imported. |
| |
| The context could be a loaded (package) module and the imported module |
| will be looked for within that package. The context could also be None, |
| meaning there is no context -- the module should be looked for as a |
| "top-level" module. |
| """ |
| |
| if not globals or not globals.get('__importer__'): |
| # globals does not refer to one of our modules or packages. That |
| # implies there is no relative import context (as far as we are |
| # concerned), and it should just pick it off the standard path. |
| return None |
| |
| # The globals refer to a module or package of ours. It will define |
| # the context of the new import. Get the module/package fqname. |
| parent_fqname = globals['__name__'] |
| |
| # if a package is performing the import, then return itself (imports |
| # refer to pkg contents) |
| if globals['__ispkg__']: |
| parent = sys.modules[parent_fqname] |
| assert globals is parent.__dict__ |
| return parent |
| |
| i = parent_fqname.rfind('.') |
| |
| # a module outside of a package has no particular import context |
| if i == -1: |
| return None |
| |
| # if a module in a package is performing the import, then return the |
| # package (imports refer to siblings) |
| parent_fqname = parent_fqname[:i] |
| parent = sys.modules[parent_fqname] |
| assert parent.__name__ == parent_fqname |
| return parent |
| |
| def _import_top_module(self, name): |
| # scan sys.path looking for a location in the filesystem that contains |
| # the module, or an Importer object that can import the module. |
| for item in sys.path: |
| if isinstance(item, _StringType): |
| module = self.fs_imp.import_from_dir(item, name) |
| else: |
| module = item.import_top(name) |
| if module: |
| return module |
| return None |
| |
| def _reload_hook(self, module): |
| "Python calls this hook to reload a module." |
| |
| # reloading of a module may or may not be possible (depending on the |
| # importer), but at least we can validate that it's ours to reload |
| importer = module.__dict__.get('__importer__') |
| if not importer: |
| ### oops. now what... |
| pass |
| |
| # okay. it is using the imputil system, and we must delegate it, but |
| # we don't know what to do (yet) |
| ### we should blast the module dict and do another get_code(). need to |
| ### flesh this out and add proper docco... |
| raise SystemError, "reload not yet implemented" |
| |
| |
| class Importer: |
| "Base class for replacing standard import functions." |
| |
| def import_top(self, name): |
| "Import a top-level module." |
| return self._import_one(None, name, name) |
| |
| ###################################################################### |
| # |
| # PRIVATE METHODS |
| # |
| def _finish_import(self, top, parts, fromlist): |
| # if "a.b.c" was provided, then load the ".b.c" portion down from |
| # below the top-level module. |
| bottom = self._load_tail(top, parts) |
| |
| # if the form is "import a.b.c", then return "a" |
| if not fromlist: |
| # no fromlist: return the top of the import tree |
| return top |
| |
| # the top module was imported by self. |
| # |
| # this means that the bottom module was also imported by self (just |
| # now, or in the past and we fetched it from sys.modules). |
| # |
| # since we imported/handled the bottom module, this means that we can |
| # also handle its fromlist (and reliably use __ispkg__). |
| |
| # if the bottom node is a package, then (potentially) import some |
| # modules. |
| # |
| # note: if it is not a package, then "fromlist" refers to names in |
| # the bottom module rather than modules. |
| # note: for a mix of names and modules in the fromlist, we will |
| # import all modules and insert those into the namespace of |
| # the package module. Python will pick up all fromlist names |
| # from the bottom (package) module; some will be modules that |
| # we imported and stored in the namespace, others are expected |
| # to be present already. |
| if bottom.__ispkg__: |
| self._import_fromlist(bottom, fromlist) |
| |
| # if the form is "from a.b import c, d" then return "b" |
| return bottom |
| |
| def _import_one(self, parent, modname, fqname): |
| "Import a single module." |
| |
| # has the module already been imported? |
| try: |
| return sys.modules[fqname] |
| except KeyError: |
| pass |
| |
| # load the module's code, or fetch the module itself |
| result = self.get_code(parent, modname, fqname) |
| if result is None: |
| return None |
| |
| module = self._process_result(result, fqname) |
| |
| # insert the module into its parent |
| if parent: |
| setattr(parent, modname, module) |
| return module |
| |
| def _process_result(self, result, fqname): |
| ispkg, code, values = result |
| # did get_code() return an actual module? (rather than a code object) |
| is_module = isinstance(code, _ModuleType) |
| |
| # use the returned module, or create a new one to exec code into |
| if is_module: |
| module = code |
| else: |
| module = imp.new_module(fqname) |
| |
| ### record packages a bit differently?? |
| module.__importer__ = self |
| module.__ispkg__ = ispkg |
| |
| # insert additional values into the module (before executing the code) |
| module.__dict__.update(values) |
| |
| # the module is almost ready... make it visible |
| sys.modules[fqname] = module |
| |
| # execute the code within the module's namespace |
| if not is_module: |
| try: |
| exec code in module.__dict__ |
| except: |
| if fqname in sys.modules: |
| del sys.modules[fqname] |
| raise |
| |
| # fetch from sys.modules instead of returning module directly. |
| # also make module's __name__ agree with fqname, in case |
| # the "exec code in module.__dict__" played games on us. |
| module = sys.modules[fqname] |
| module.__name__ = fqname |
| return module |
| |
| def _load_tail(self, m, parts): |
| """Import the rest of the modules, down from the top-level module. |
| |
| Returns the last module in the dotted list of modules. |
| """ |
| for part in parts: |
| fqname = "%s.%s" % (m.__name__, part) |
| m = self._import_one(m, part, fqname) |
| if not m: |
| raise ImportError, "No module named " + fqname |
| return m |
| |
| def _import_fromlist(self, package, fromlist): |
| 'Import any sub-modules in the "from" list.' |
| |
| # if '*' is present in the fromlist, then look for the '__all__' |
| # variable to find additional items (modules) to import. |
| if '*' in fromlist: |
| fromlist = list(fromlist) + \ |
| list(package.__dict__.get('__all__', [])) |
| |
| for sub in fromlist: |
| # if the name is already present, then don't try to import it (it |
| # might not be a module!). |
| if sub != '*' and not hasattr(package, sub): |
| subname = "%s.%s" % (package.__name__, sub) |
| submod = self._import_one(package, sub, subname) |
| if not submod: |
| raise ImportError, "cannot import name " + subname |
| |
| def _do_import(self, parent, parts, fromlist): |
| """Attempt to import the module relative to parent. |
| |
| This method is used when the import context specifies that <self> |
| imported the parent module. |
| """ |
| top_name = parts[0] |
| top_fqname = parent.__name__ + '.' + top_name |
| top_module = self._import_one(parent, top_name, top_fqname) |
| if not top_module: |
| # this importer and parent could not find the module (relatively) |
| return None |
| |
| return self._finish_import(top_module, parts[1:], fromlist) |
| |
| ###################################################################### |
| # |
| # METHODS TO OVERRIDE |
| # |
| def get_code(self, parent, modname, fqname): |
| """Find and retrieve the code for the given module. |
| |
| parent specifies a parent module to define a context for importing. It |
| may be None, indicating no particular context for the search. |
| |
| modname specifies a single module (not dotted) within the parent. |
| |
| fqname specifies the fully-qualified module name. This is a |
| (potentially) dotted name from the "root" of the module namespace |
| down to the modname. |
| If there is no parent, then modname==fqname. |
| |
| This method should return None, or a 3-tuple. |
| |
| * If the module was not found, then None should be returned. |
| |
| * The first item of the 2- or 3-tuple should be the integer 0 or 1, |
| specifying whether the module that was found is a package or not. |
| |
| * The second item is the code object for the module (it will be |
| executed within the new module's namespace). This item can also |
| be a fully-loaded module object (e.g. loaded from a shared lib). |
| |
| * The third item is a dictionary of name/value pairs that will be |
| inserted into new module before the code object is executed. This |
| is provided in case the module's code expects certain values (such |
| as where the module was found). When the second item is a module |
| object, then these names/values will be inserted *after* the module |
| has been loaded/initialized. |
| """ |
| raise RuntimeError, "get_code not implemented" |
| |
| |
| ###################################################################### |
| # |
| # Some handy stuff for the Importers |
| # |
| |
| # byte-compiled file suffix character |
| _suffix_char = __debug__ and 'c' or 'o' |
| |
| # byte-compiled file suffix |
| _suffix = '.py' + _suffix_char |
| |
| def _compile(pathname, timestamp): |
| """Compile (and cache) a Python source file. |
| |
| The file specified by <pathname> is compiled to a code object and |
| returned. |
| |
| Presuming the appropriate privileges exist, the bytecodes will be |
| saved back to the filesystem for future imports. The source file's |
| modification timestamp must be provided as a Long value. |
| """ |
| codestring = open(pathname, 'rU').read() |
| if codestring and codestring[-1] != '\n': |
| codestring = codestring + '\n' |
| code = __builtin__.compile(codestring, pathname, 'exec') |
| |
| # try to cache the compiled code |
| try: |
| f = open(pathname + _suffix_char, 'wb') |
| except IOError: |
| pass |
| else: |
| f.write('\0\0\0\0') |
| f.write(struct.pack('<I', timestamp)) |
| marshal.dump(code, f) |
| f.flush() |
| f.seek(0, 0) |
| f.write(imp.get_magic()) |
| f.close() |
| |
| return code |
| |
| _os_stat = _os_path_join = None |
| def _os_bootstrap(): |
| "Set up 'os' module replacement functions for use during import bootstrap." |
| |
| names = sys.builtin_module_names |
| |
| join = None |
| if 'posix' in names: |
| sep = '/' |
| from posix import stat |
| elif 'nt' in names: |
| sep = '\\' |
| from nt import stat |
| elif 'dos' in names: |
| sep = '\\' |
| from dos import stat |
| elif 'os2' in names: |
| sep = '\\' |
| from os2 import stat |
| else: |
| raise ImportError, 'no os specific module found' |
| |
| if join is None: |
| def join(a, b, sep=sep): |
| if a == '': |
| return b |
| lastchar = a[-1:] |
| if lastchar == '/' or lastchar == sep: |
| return a + b |
| return a + sep + b |
| |
| global _os_stat |
| _os_stat = stat |
| |
| global _os_path_join |
| _os_path_join = join |
| |
| def _os_path_isdir(pathname): |
| "Local replacement for os.path.isdir()." |
| try: |
| s = _os_stat(pathname) |
| except OSError: |
| return None |
| return (s.st_mode & 0170000) == 0040000 |
| |
| def _timestamp(pathname): |
| "Return the file modification time as a Long." |
| try: |
| s = _os_stat(pathname) |
| except OSError: |
| return None |
| return long(s.st_mtime) |
| |
| |
| ###################################################################### |
| # |
| # Emulate the import mechanism for builtin and frozen modules |
| # |
| class BuiltinImporter(Importer): |
| def get_code(self, parent, modname, fqname): |
| if parent: |
| # these modules definitely do not occur within a package context |
| return None |
| |
| # look for the module |
| if imp.is_builtin(modname): |
| type = imp.C_BUILTIN |
| elif imp.is_frozen(modname): |
| type = imp.PY_FROZEN |
| else: |
| # not found |
| return None |
| |
| # got it. now load and return it. |
| module = imp.load_module(modname, None, modname, ('', '', type)) |
| return 0, module, { } |
| |
| |
| ###################################################################### |
| # |
| # Internal importer used for importing from the filesystem |
| # |
| class _FilesystemImporter(Importer): |
| def __init__(self): |
| self.suffixes = [ ] |
| |
| def add_suffix(self, suffix, importFunc): |
| assert hasattr(importFunc, '__call__') |
| self.suffixes.append((suffix, importFunc)) |
| |
| def import_from_dir(self, dir, fqname): |
| result = self._import_pathname(_os_path_join(dir, fqname), fqname) |
| if result: |
| return self._process_result(result, fqname) |
| return None |
| |
| def get_code(self, parent, modname, fqname): |
| # This importer is never used with an empty parent. Its existence is |
| # private to the ImportManager. The ImportManager uses the |
| # import_from_dir() method to import top-level modules/packages. |
| # This method is only used when we look for a module within a package. |
| assert parent |
| |
| for submodule_path in parent.__path__: |
| code = self._import_pathname(_os_path_join(submodule_path, modname), fqname) |
| if code is not None: |
| return code |
| return self._import_pathname(_os_path_join(parent.__pkgdir__, modname), |
| fqname) |
| |
| 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: |
| # type(sys) is not a module in Jython. what to use instead? |
| # imp.C_EXTENSION is not in Jython. 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] |
| # 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[...] is 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. |
| # |
