Brett Cannon | 23cbd8a | 2009-01-18 00:24:28 +0000 | [diff] [blame^] | 1 | """Core implementation of import. |
| 2 | |
| 3 | This module is NOT meant to be directly imported! It has been designed such |
| 4 | that it can be bootstrapped into Python as the implementation of import. As |
| 5 | such it requires the injection of specific modules and attributes in order to |
| 6 | work. One should use importlib as the public-facing version of this module. |
| 7 | |
| 8 | """ |
| 9 | |
| 10 | # Injected modules are '_warnings', 'imp', 'sys', 'marshal', 'errno', and '_os' |
| 11 | # (a.k.a. 'posix', 'nt' or 'os2'). |
| 12 | # Injected attribute is path_sep. |
| 13 | # |
| 14 | # When editing this code be aware that code executed at import time CANNOT |
| 15 | # reference any injected objects! This includes not only global code but also |
| 16 | # anything specified at the class level. |
| 17 | |
| 18 | |
| 19 | # XXX Could also expose Modules/getpath.c:joinpath() |
| 20 | def _path_join(*args): |
| 21 | """Replacement for os.path.join.""" |
| 22 | return path_sep.join(x[:-len(path_sep)] if x.endswith(path_sep) else x |
| 23 | for x in args) |
| 24 | |
| 25 | |
| 26 | def _path_exists(path): |
| 27 | """Replacement for os.path.exists.""" |
| 28 | try: |
| 29 | _os.stat(path) |
| 30 | except OSError: |
| 31 | return False |
| 32 | else: |
| 33 | return True |
| 34 | |
| 35 | |
| 36 | def _path_is_mode_type(path, mode): |
| 37 | """Test whether the path is the specified mode type.""" |
| 38 | try: |
| 39 | stat_info = _os.stat(path) |
| 40 | except OSError: |
| 41 | return False |
| 42 | return (stat_info.st_mode & 0o170000) == mode |
| 43 | |
| 44 | |
| 45 | # XXX Could also expose Modules/getpath.c:isfile() |
| 46 | def _path_isfile(path): |
| 47 | """Replacement for os.path.isfile.""" |
| 48 | return _path_is_mode_type(path, 0o100000) |
| 49 | |
| 50 | |
| 51 | # XXX Could also expose Modules/getpath.c:isdir() |
| 52 | def _path_isdir(path): |
| 53 | """Replacement for os.path.isdir.""" |
| 54 | return _path_is_mode_type(path, 0o040000) |
| 55 | |
| 56 | |
| 57 | def _path_without_ext(path, ext_type): |
| 58 | """Replacement for os.path.splitext()[0].""" |
| 59 | for suffix in suffix_list(ext_type): |
| 60 | if path.endswith(suffix): |
| 61 | return path[:-len(suffix)] |
| 62 | else: |
| 63 | raise ValueError("path is not of the specified type") |
| 64 | |
| 65 | |
| 66 | def _path_absolute(path): |
| 67 | """Replacement for os.path.abspath.""" |
| 68 | if not path: |
| 69 | path = _os.getcwd() |
| 70 | try: |
| 71 | return _os._getfullpathname(path) |
| 72 | except AttributeError: |
| 73 | if path.startswith('/'): |
| 74 | return path |
| 75 | else: |
| 76 | return _path_join(_os.getcwd(), path) |
| 77 | |
| 78 | |
| 79 | class closing: |
| 80 | |
| 81 | """Simple replacement for contextlib.closing.""" |
| 82 | |
| 83 | def __init__(self, obj): |
| 84 | self.obj = obj |
| 85 | |
| 86 | def __enter__(self): |
| 87 | return self.obj |
| 88 | |
| 89 | def __exit__(self, *args): |
| 90 | self.obj.close() |
| 91 | |
| 92 | |
| 93 | class _BuiltinFrozenBaseLoader(object): |
| 94 | |
| 95 | """Base class for meta_path loaders for built-in and frozen modules. |
| 96 | |
| 97 | Subclasses must implement: |
| 98 | |
| 99 | * _find(fullname:str) -> bool |
| 100 | Finder which returns whether the class can handle the module. |
| 101 | |
| 102 | * _load(fullname:str) -> module |
| 103 | Loader which returns the loaded module. The check for sys.modules |
| 104 | does not need to be handled by this method. |
| 105 | |
| 106 | * type_:str |
| 107 | Name of the type of module being handled. Used in error messages. |
| 108 | |
| 109 | """ |
| 110 | |
| 111 | def find_module(self, fullname, path=None): |
| 112 | """Find a module.""" |
| 113 | if not self._find(fullname): |
| 114 | return None |
| 115 | return self |
| 116 | |
| 117 | def load_module(self, fullname): |
| 118 | """Load a module.""" |
| 119 | try: |
| 120 | return sys.modules[fullname] |
| 121 | except KeyError: |
| 122 | pass |
| 123 | mod = self._load(fullname) |
| 124 | if not mod: |
| 125 | raise ImportError("expected {0} module not " |
| 126 | "loaded".format(self.type_)) |
| 127 | return mod |
| 128 | |
| 129 | |
| 130 | class BuiltinImporter(_BuiltinFrozenBaseLoader): |
| 131 | |
| 132 | """Meta path loader for built-in modules.""" |
| 133 | |
| 134 | type_ = "built-in" |
| 135 | |
| 136 | def __init__(self): |
| 137 | """Set the methods needed by the class. |
| 138 | |
| 139 | Cannot be set at the class level because the imp module is not |
| 140 | necessarily injected until after the class is created. |
| 141 | |
| 142 | """ |
| 143 | self._find = imp.is_builtin |
| 144 | self._load = imp.init_builtin |
| 145 | |
| 146 | def find_module(self, fullname, path=None): |
| 147 | """Try to find the built-in module. |
| 148 | |
| 149 | If 'path' is ever specified then the search is considered a failure. |
| 150 | |
| 151 | """ |
| 152 | if path is not None: |
| 153 | return None |
| 154 | return super().find_module(fullname, path) |
| 155 | |
| 156 | def load_module(self, fullname): |
| 157 | """Load a built-in module.""" |
| 158 | if fullname not in sys.builtin_module_names: |
| 159 | raise ImportError("{0} is not a built-in module".format(fullname)) |
| 160 | return super().load_module(fullname) |
| 161 | |
| 162 | |
| 163 | class FrozenImporter(_BuiltinFrozenBaseLoader): |
| 164 | |
| 165 | """Meta path class for importing frozen modules.""" |
| 166 | |
| 167 | type_ = 'frozen' |
| 168 | |
| 169 | def __init__(self): |
| 170 | """Specify the methods needed by the superclass. |
| 171 | |
| 172 | Because imp may not be injected until after class creation these |
| 173 | methods cannot be set at the class level. |
| 174 | |
| 175 | """ |
| 176 | self._find = imp.is_frozen |
| 177 | self._load = imp.init_frozen |
| 178 | |
| 179 | def load_module(self, fullname): |
| 180 | """Load a frozen module.""" |
| 181 | if not self.find_module(fullname): |
| 182 | raise ImportError("{0} is not a frozen module".format(fullname)) |
| 183 | return super().load_module(fullname) |
| 184 | |
| 185 | |
| 186 | class ChainedImporter(object): |
| 187 | |
| 188 | """Finder that sequentially calls other finders.""" |
| 189 | |
| 190 | def __init__(self, *importers): |
| 191 | self._importers = importers |
| 192 | |
| 193 | def find_module(self, fullname, path=None): |
| 194 | for importer in self._importers: |
| 195 | result = importer.find_module(fullname, path) |
| 196 | if result: |
| 197 | return result |
| 198 | else: |
| 199 | return None |
| 200 | |
| 201 | |
| 202 | # XXX Don't make filesystem-specific and instead make generic for any path |
| 203 | # hooks. |
| 204 | def chaining_fs_path_hook(*path_hooks): |
| 205 | """Create a closure which calls the path hooks sequentially looking for |
| 206 | which path hooks can handle a path entry. |
| 207 | |
| 208 | |
| 209 | Passed-in path hooks work as any other path hooks, raising ImportError if |
| 210 | they cannot handle the path, otherwise returning a finder. |
| 211 | |
| 212 | """ |
| 213 | def chained_fs_path_hook(path_entry): |
| 214 | """Closure which sees which of the captured path hooks can handle the |
| 215 | path entry.""" |
| 216 | absolute_path = _path_absolute(path_entry) |
| 217 | if not _path_isdir(absolute_path): |
| 218 | raise ImportError("only directories are supported") |
| 219 | accepted = [] |
| 220 | for path_hook in path_hooks: |
| 221 | try: |
| 222 | accepted.append(path_hook(absolute_path)) |
| 223 | except ImportError: |
| 224 | continue |
| 225 | if not accepted: |
| 226 | raise ImportError("no path hooks could handle %s" % path_entry) |
| 227 | return ChainedImporter(*accepted) |
| 228 | return chained_fs_path_hook |
| 229 | |
| 230 | |
| 231 | def check_name(method): |
| 232 | """Decorator to verify that the module being requested matches the one the |
| 233 | loader can handle. |
| 234 | |
| 235 | The first argument (self) must define _name which the second argument is |
| 236 | comapred against. If the comparison fails then ImportError is raised. |
| 237 | |
| 238 | """ |
| 239 | def inner(self, name, *args, **kwargs): |
| 240 | if self._name != name: |
| 241 | raise ImportError("loader cannot handle %s" % name) |
| 242 | return method(self, name, *args, **kwargs) |
| 243 | inner.__name__ = method.__name__ |
| 244 | inner.__doc__ = method.__doc__ |
| 245 | inner.__dict__.update(method.__dict__) |
| 246 | return inner |
| 247 | |
| 248 | |
| 249 | class _ExtensionFileLoader(object): |
| 250 | |
| 251 | """Loader for extension modules. |
| 252 | |
| 253 | The constructor is designed to work with FileImporter. |
| 254 | |
| 255 | """ |
| 256 | |
| 257 | def __init__(self, name, path, is_pkg): |
| 258 | """Initialize the loader. |
| 259 | |
| 260 | If is_pkg is True then an exception is raised as extension modules |
| 261 | cannot be the __init__ module for an extension module. |
| 262 | |
| 263 | """ |
| 264 | self._name = name |
| 265 | self._path = path |
| 266 | if is_pkg: |
| 267 | raise ValueError("extension modules cannot be packages") |
| 268 | |
| 269 | @check_name |
| 270 | def load_module(self, fullname): |
| 271 | """Load an extension module.""" |
| 272 | assert self._name == fullname |
| 273 | try: |
| 274 | module = imp.load_dynamic(fullname, self._path) |
| 275 | module.__loader__ = self |
| 276 | return module |
| 277 | except: |
| 278 | # If an error occurred, don't leave a partially initialized module. |
| 279 | if fullname in sys.modules: |
| 280 | del sys.modules[fullname] |
| 281 | raise |
| 282 | |
| 283 | @check_name |
| 284 | def is_package(self, fullname): |
| 285 | """Return False as an extension module can never be a package.""" |
| 286 | return False |
| 287 | |
| 288 | @check_name |
| 289 | def get_code(self, fullname): |
| 290 | """Return None as an extension module cannot create a code object.""" |
| 291 | return None |
| 292 | |
| 293 | @check_name |
| 294 | def get_source(self, fullname): |
| 295 | """Return None as extension modules have no source code.""" |
| 296 | return None |
| 297 | |
| 298 | |
| 299 | def suffix_list(suffix_type): |
| 300 | """Return a list of file suffixes based on the imp file type.""" |
| 301 | return [suffix[0] for suffix in imp.get_suffixes() |
| 302 | if suffix[2] == suffix_type] |
| 303 | |
| 304 | |
| 305 | # XXX Need a better name. |
| 306 | def get_module(fxn): |
| 307 | """Decorator to handle selecting the proper module for load_module |
| 308 | implementations. |
| 309 | |
| 310 | Decorated modules are passed the module to use instead of the module name. |
| 311 | The module is either from sys.modules if it already exists (for reloading) |
| 312 | or is a new module which has __name__ set. If any exception is raised by |
| 313 | the decorated method then __loader__, __name__, __file__, and __path__ are |
| 314 | all restored on the module to their original values. |
| 315 | |
| 316 | """ |
| 317 | def decorated(self, fullname): |
| 318 | module = sys.modules.get(fullname) |
| 319 | is_reload = bool(module) |
| 320 | if not is_reload: |
| 321 | # This must be done before open() is called as the 'io' module |
| 322 | # implicitly imports 'locale' and would otherwise trigger an |
| 323 | # infinite loop. |
| 324 | module = imp.new_module(fullname) |
| 325 | module.__name__ = fullname |
| 326 | sys.modules[fullname] = module |
| 327 | else: |
| 328 | original_values = {} |
| 329 | modified_attrs = ['__loader__', '__name__', '__file__', '__path__'] |
| 330 | for attr in modified_attrs: |
| 331 | try: |
| 332 | original_values[attr] = getattr(module, attr) |
| 333 | except AttributeError: |
| 334 | pass |
| 335 | try: |
| 336 | return fxn(self, module) |
| 337 | except: |
| 338 | if not is_reload: |
| 339 | del sys.modules[fullname] |
| 340 | else: |
| 341 | for attr in modified_attrs: |
| 342 | if attr in original_values: |
| 343 | setattr(module, attr, original_values[attr]) |
| 344 | elif hasattr(module, attr): |
| 345 | delattr(module, attr) |
| 346 | raise |
| 347 | return decorated |
| 348 | |
| 349 | |
| 350 | class _PyFileLoader(object): |
| 351 | # XXX Still smart to have this as a separate class? Or would it work |
| 352 | # better to integrate with PyFileImporter? Could cache _is_pkg info. |
| 353 | # FileImporter can be changed to return self instead of a specific loader |
| 354 | # call. Otherwise _base_path can be calculated on the fly without issue if |
| 355 | # it is known whether a module should be treated as a path or package to |
| 356 | # minimize stat calls. Could even go as far as to stat the directory the |
| 357 | # importer is in to detect changes and then cache all the info about what |
| 358 | # files were found (if stating directories is platform-dependent). |
| 359 | |
| 360 | """Load a Python source or bytecode file.""" |
| 361 | |
| 362 | def __init__(self, name, path, is_pkg): |
| 363 | self._name = name |
| 364 | self._is_pkg = is_pkg |
| 365 | # Figure out the base path based on whether it was source or bytecode |
| 366 | # that was found. |
| 367 | try: |
| 368 | self._base_path = _path_without_ext(path, imp.PY_SOURCE) |
| 369 | except ValueError: |
| 370 | self._base_path = _path_without_ext(path, imp.PY_COMPILED) |
| 371 | |
| 372 | def _find_path(self, ext_type): |
| 373 | """Find a path from the base path and the specified extension type that |
| 374 | exists, returning None if one is not found.""" |
| 375 | for suffix in suffix_list(ext_type): |
| 376 | path = self._base_path + suffix |
| 377 | if _path_exists(path): |
| 378 | return path |
| 379 | else: |
| 380 | return None |
| 381 | |
| 382 | def _source_path(self): |
| 383 | """Return the path to an existing source file for the module, or None |
| 384 | if one cannot be found.""" |
| 385 | # Not a property so that it is easy to override. |
| 386 | return self._find_path(imp.PY_SOURCE) |
| 387 | |
| 388 | def _bytecode_path(self): |
| 389 | """Return the path to a bytecode file, or None if one does not |
| 390 | exist.""" |
| 391 | # Not a property for easy overriding. |
| 392 | return self._find_path(imp.PY_COMPILED) |
| 393 | |
| 394 | @check_name |
| 395 | @get_module |
| 396 | def load_module(self, module): |
| 397 | """Load a Python source or bytecode module.""" |
| 398 | source_path = self._source_path() |
| 399 | bytecode_path = self._bytecode_path() |
| 400 | code_object = self.get_code(module.__name__) |
| 401 | module.__file__ = source_path if source_path else bytecode_path |
| 402 | module.__loader__ = self |
| 403 | if self._is_pkg: |
| 404 | module.__path__ = [module.__file__.rsplit(path_sep, 1)[0]] |
| 405 | module.__package__ = module.__name__ |
| 406 | elif '.' in module.__name__: |
| 407 | module.__package__ = module.__name__.rsplit('.', 1)[0] |
| 408 | else: |
| 409 | module.__package__ = None |
| 410 | exec(code_object, module.__dict__) |
| 411 | return module |
| 412 | |
| 413 | @check_name |
| 414 | def source_mtime(self, name): |
| 415 | """Return the modification time of the source for the specified |
| 416 | module.""" |
| 417 | source_path = self._source_path() |
| 418 | if not source_path: |
| 419 | return None |
| 420 | return int(_os.stat(source_path).st_mtime) |
| 421 | |
| 422 | @check_name |
| 423 | def get_source(self, fullname): |
| 424 | """Return the source for the module as a string. |
| 425 | |
| 426 | Return None if the source is not available. Raise ImportError if the |
| 427 | laoder cannot handle the specified module. |
| 428 | |
| 429 | """ |
| 430 | source_path = self._source_path() |
| 431 | if source_path is None: |
| 432 | return None |
| 433 | import tokenize |
| 434 | with closing(_fileio_FileIO(source_path, 'r')) as file: |
| 435 | encoding, lines = tokenize.detect_encoding(file.readline) |
| 436 | # XXX Will fail when passed to compile() if the encoding is |
| 437 | # anything other than UTF-8. |
| 438 | return open(source_path, encoding=encoding).read() |
| 439 | |
| 440 | @check_name |
| 441 | def read_source(self, fullname): |
| 442 | """Return the source for the specified module as bytes along with the |
| 443 | path where the source came from. |
| 444 | |
| 445 | The returned path is used by 'compile' for error messages. |
| 446 | |
| 447 | """ |
| 448 | source_path = self._source_path() |
| 449 | if source_path is None: |
| 450 | return None |
| 451 | with closing(_fileio._FileIO(source_path, 'r')) as bytes_file: |
| 452 | return bytes_file.read(), source_path |
| 453 | |
| 454 | @check_name |
| 455 | def read_bytecode(self, name): |
| 456 | """Return the magic number, timestamp, and the module bytecode for the |
| 457 | module. |
| 458 | |
| 459 | Raises ImportError (just like get_source) if the laoder cannot handle |
| 460 | the module. Returns None if there is no bytecode. |
| 461 | |
| 462 | """ |
| 463 | path = self._bytecode_path() |
| 464 | if path is None: |
| 465 | return None |
| 466 | file = _fileio._FileIO(path, 'r') |
| 467 | try: |
| 468 | with closing(file) as bytecode_file: |
| 469 | data = bytecode_file.read() |
| 470 | return data[:4], marshal._r_long(data[4:8]), data[8:] |
| 471 | except AttributeError: |
| 472 | return None |
| 473 | |
| 474 | @check_name |
| 475 | def write_bytecode(self, name, magic, timestamp, data): |
| 476 | """Write out 'data' for the specified module using the specific |
| 477 | timestamp, returning a boolean |
| 478 | signifying if the write-out actually occurred. |
| 479 | |
| 480 | Raises ImportError (just like get_source) if the specified module |
| 481 | cannot be handled by the loader. |
| 482 | |
| 483 | """ |
| 484 | bytecode_path = self._bytecode_path() |
| 485 | if not bytecode_path: |
| 486 | bytecode_path = self._base_path + suffix_list(imp.PY_COMPILED)[0] |
| 487 | file = _fileio._FileIO(bytecode_path, 'w') |
| 488 | try: |
| 489 | with closing(file) as bytecode_file: |
| 490 | bytecode_file.write(magic) |
| 491 | bytecode_file.write(marshal._w_long(timestamp)) |
| 492 | bytecode_file.write(data) |
| 493 | return True |
| 494 | except IOError as exc: |
| 495 | if exc.errno == errno.EACCES: |
| 496 | return False |
| 497 | else: |
| 498 | raise |
| 499 | |
| 500 | # XXX Take an optional argument to flag whether to write bytecode? |
| 501 | @check_name |
| 502 | def get_code(self, name): |
| 503 | """Return the code object for the module. |
| 504 | |
| 505 | 'self' must implement: |
| 506 | |
| 507 | * read_bytecode(name:str) -> (int, int, bytes) or None |
| 508 | Return the magic number, timestamp, and bytecode for the |
| 509 | module. None is returned if not bytecode is available. |
| 510 | |
| 511 | * source_mtime(name:str) -> int |
| 512 | Return the last modification time for the source of the module. |
| 513 | Returns None if their is no source. |
| 514 | |
| 515 | * read_source(name:str) -> (bytes, str) |
| 516 | Return the source code for the module and the path to use in |
| 517 | the call to 'compile'. Not called if source_mtime returned |
| 518 | None. |
| 519 | |
| 520 | * write_bytecode(name:str, magic:bytes, timestamp:int, data:str) |
| 521 | Write out bytecode for the module with the specified magic |
| 522 | number and timestamp. Not called if sys.dont_write_bytecode is |
| 523 | True. |
| 524 | |
| 525 | """ |
| 526 | # XXX Care enough to make sure this call does not happen if the magic |
| 527 | # number is bad? |
| 528 | source_timestamp = self.source_mtime(name) |
| 529 | # Try to use bytecode if it is available. |
| 530 | bytecode_tuple = self.read_bytecode(name) |
| 531 | if bytecode_tuple: |
| 532 | magic, pyc_timestamp, bytecode = bytecode_tuple |
| 533 | try: |
| 534 | # Verify that the magic number is valid. |
| 535 | if imp.get_magic() != magic: |
| 536 | raise ImportError("bad magic number") |
| 537 | # Verify that the bytecode is not stale (only matters when |
| 538 | # there is source to fall back on. |
| 539 | if source_timestamp: |
| 540 | if pyc_timestamp < source_timestamp: |
| 541 | raise ImportError("bytcode is stale") |
| 542 | except ImportError: |
| 543 | # If source is available give it a shot. |
| 544 | if source_timestamp is not None: |
| 545 | pass |
| 546 | else: |
| 547 | raise |
| 548 | else: |
| 549 | # Bytecode seems fine, so try to use it. |
| 550 | # XXX If the bytecode is ill-formed, would it be beneficial to |
| 551 | # try for using source if available and issue a warning? |
| 552 | return marshal.loads(bytecode) |
| 553 | elif source_timestamp is None: |
| 554 | raise ImportError("no source or bytecode available to create code " |
| 555 | "object for {0!r}".format(name)) |
| 556 | # Use the source. |
| 557 | source, source_path = self.read_source(name) |
| 558 | # Convert to universal newlines. |
| 559 | line_endings = b'\n' |
| 560 | for index, c in enumerate(source): |
| 561 | if c == ord(b'\n'): |
| 562 | break |
| 563 | elif c == ord(b'\r'): |
| 564 | line_endings = b'\r' |
| 565 | try: |
| 566 | if source[index+1] == ord(b'\n'): |
| 567 | line_endings += b'\n' |
| 568 | except IndexError: |
| 569 | pass |
| 570 | break |
| 571 | if line_endings != b'\n': |
| 572 | source = source.replace(line_endings, b'\n') |
| 573 | code_object = compile(source, source_path, 'exec', dont_inherit=True) |
| 574 | # Generate bytecode and write it out. |
| 575 | if not sys.dont_write_bytecode: |
| 576 | data = marshal.dumps(code_object) |
| 577 | self.write_bytecode(name, imp.get_magic(), source_timestamp, data) |
| 578 | return code_object |
| 579 | |
| 580 | def get_data(self, path): |
| 581 | """Return the data from path as raw bytes.""" |
| 582 | return _fileio._FileIO(path, 'r').read() |
| 583 | |
| 584 | @check_name |
| 585 | def is_package(self, fullname): |
| 586 | """Return a boolean based on whether the module is a package. |
| 587 | |
| 588 | Raises ImportError (like get_source) if the loader cannot handle the |
| 589 | package. |
| 590 | |
| 591 | """ |
| 592 | return self._is_pkg |
| 593 | |
| 594 | |
| 595 | class FileImporter(object): |
| 596 | |
| 597 | """Base class for file importers. |
| 598 | |
| 599 | Subclasses are expected to define the following attributes: |
| 600 | |
| 601 | * _suffixes |
| 602 | Sequence of file suffixes whose order will be followed. |
| 603 | |
| 604 | * _possible_package |
| 605 | True if importer should check for packages. |
| 606 | |
| 607 | * _loader |
| 608 | A callable that takes the module name, a file path, and whether |
| 609 | the path points to a package and returns a loader for the module |
| 610 | found at that path. |
| 611 | |
| 612 | """ |
| 613 | |
| 614 | def __init__(self, path_entry): |
| 615 | """Initialize an importer for the passed-in sys.path entry (which is |
| 616 | assumed to have already been verified as an existing directory). |
| 617 | |
| 618 | Can be used as an entry on sys.path_hook. |
| 619 | |
| 620 | """ |
| 621 | self._path_entry = path_entry |
| 622 | |
| 623 | def find_module(self, fullname, path=None): |
| 624 | tail_module = fullname.rsplit('.', 1)[-1] |
| 625 | package_directory = None |
| 626 | if self._possible_package: |
| 627 | for ext in self._suffixes: |
| 628 | package_directory = _path_join(self._path_entry, tail_module) |
| 629 | init_filename = '__init__' + ext |
| 630 | package_init = _path_join(package_directory, init_filename) |
| 631 | if (_path_isfile(package_init) and |
| 632 | _case_ok(self._path_entry, tail_module) and |
| 633 | _case_ok(package_directory, init_filename)): |
| 634 | return self._loader(fullname, package_init, True) |
| 635 | for ext in self._suffixes: |
| 636 | file_name = tail_module + ext |
| 637 | file_path = _path_join(self._path_entry, file_name) |
| 638 | if (_path_isfile(file_path) and |
| 639 | _case_ok(self._path_entry, file_name)): |
| 640 | return self._loader(fullname, file_path, False) |
| 641 | else: |
| 642 | # Raise a warning if it matches a directory w/o an __init__ file. |
| 643 | if (package_directory is not None and |
| 644 | _path_isdir(package_directory) and |
| 645 | _case_ok(self._path_entry, tail_module)): |
| 646 | _warnings.warn("Not importing directory %s: missing __init__" |
| 647 | % package_directory, ImportWarning) |
| 648 | return None |
| 649 | |
| 650 | |
| 651 | class ExtensionFileImporter(FileImporter): |
| 652 | |
| 653 | """Importer for extension files.""" |
| 654 | |
| 655 | _possible_package = False |
| 656 | _loader = _ExtensionFileLoader |
| 657 | |
| 658 | def __init__(self, path_entry): |
| 659 | # Assigning to _suffixes here instead of at the class level because |
| 660 | # imp is not imported at the time of class creation. |
| 661 | self._suffixes = suffix_list(imp.C_EXTENSION) |
| 662 | super(ExtensionFileImporter, self).__init__(path_entry) |
| 663 | |
| 664 | |
| 665 | class PyFileImporter(FileImporter): |
| 666 | |
| 667 | """Importer for source/bytecode files.""" |
| 668 | |
| 669 | _possible_package = True |
| 670 | _loader = _PyFileLoader |
| 671 | |
| 672 | def __init__(self, path_entry): |
| 673 | # Lack of imp during class creation means _suffixes is set here. |
| 674 | # Make sure that Python source files are listed first! Needed for an |
| 675 | # optimization by the loader. |
| 676 | self._suffixes = suffix_list(imp.PY_SOURCE) |
| 677 | self._suffixes += suffix_list(imp.PY_COMPILED) |
| 678 | super(PyFileImporter, self).__init__(path_entry) |
| 679 | |
| 680 | |
| 681 | class ImportLockContext(object): |
| 682 | |
| 683 | """Context manager for the import lock.""" |
| 684 | |
| 685 | def __enter__(self): |
| 686 | """Acquire the import lock.""" |
| 687 | imp.acquire_lock() |
| 688 | |
| 689 | def __exit__(self, exc_type, exc_value, exc_traceback): |
| 690 | """Release the import lock regardless of any raised exceptions.""" |
| 691 | imp.release_lock() |
| 692 | |
| 693 | |
| 694 | class Import(object): |
| 695 | |
| 696 | """Class that implements the __import__ interface. |
| 697 | |
| 698 | Backwards compatibility is maintained by extending sys.meta_path |
| 699 | interally (for handling built-in and frozen modules) and providing a |
| 700 | default path hooks entry for extension modules, .py, and .pyc |
| 701 | files. Both are controlled during instance initialization. |
| 702 | |
| 703 | """ |
| 704 | |
| 705 | def __init__(self, default_path_hook=None, |
| 706 | extended_meta_path=None): |
| 707 | """Store a default path hook entry and a sequence to internally extend |
| 708 | sys.meta_path by (passing in None uses default importers).""" |
| 709 | if extended_meta_path is None: |
| 710 | self.extended_meta_path = BuiltinImporter(), FrozenImporter() |
| 711 | else: |
| 712 | self.extended_meta_path = extended_meta_path |
| 713 | self.default_path_hook = default_path_hook |
| 714 | if self.default_path_hook is None: |
| 715 | # Create a handler to deal with extension modules, .py, and .pyc |
| 716 | # files. Built-in and frozen modules are handled by sys.meta_path |
| 717 | # entries. |
| 718 | importers = [ExtensionFileImporter, PyFileImporter] |
| 719 | self.default_path_hook = chaining_fs_path_hook(*importers) |
| 720 | |
| 721 | def _search_meta_path(self, name, path=None): |
| 722 | """Check the importers on sys.meta_path for a loader along with the |
| 723 | extended meta path sequence stored within this instance. |
| 724 | |
| 725 | The extended sys.meta_path entries are searched after the entries on |
| 726 | sys.meta_path. |
| 727 | |
| 728 | """ |
| 729 | for entry in (tuple(sys.meta_path) + self.extended_meta_path): |
| 730 | loader = entry.find_module(name, path) |
| 731 | if loader: |
| 732 | return loader |
| 733 | else: |
| 734 | raise ImportError("No module named %s" % name) |
| 735 | |
| 736 | def _sys_path_importer(self, path_entry): |
| 737 | """Return the importer for the specified path, from |
| 738 | sys.path_importer_cache if possible. |
| 739 | |
| 740 | If None is stored in sys.path_importer_cache then use the default path |
| 741 | hook. |
| 742 | |
| 743 | """ |
| 744 | try: |
| 745 | # See if an importer is cached. |
| 746 | importer = sys.path_importer_cache[path_entry] |
| 747 | # If None was returned, use default importer factory. |
| 748 | if importer is None: |
| 749 | return self.default_path_hook(path_entry) |
| 750 | else: |
| 751 | return importer |
| 752 | except KeyError: |
| 753 | # No cached importer found; try to get a new one from |
| 754 | # sys.path_hooks or imp.NullImporter. |
| 755 | for importer_factory in (sys.path_hooks + [imp.NullImporter]): |
| 756 | try: |
| 757 | importer = importer_factory(path_entry) |
| 758 | sys.path_importer_cache[path_entry] = importer |
| 759 | return importer |
| 760 | except ImportError: |
| 761 | continue |
| 762 | else: |
| 763 | # No importer factory on sys.path_hooks works; use the default |
| 764 | # importer factory and store None in sys.path_importer_cache. |
| 765 | try: |
| 766 | importer = self.default_path_hook(path_entry) |
| 767 | sys.path_importer_cache[path_entry] = None |
| 768 | return importer |
| 769 | except ImportError: |
| 770 | raise ImportError("no importer found for %s" % path_entry) |
| 771 | |
| 772 | def _search_std_path(self, name, path=None): |
| 773 | """Check sys.path or 'path' (depending if 'path' is set) for the |
| 774 | named module and return its loader.""" |
| 775 | if path: |
| 776 | search_paths = path |
| 777 | else: |
| 778 | search_paths = sys.path |
| 779 | for entry in search_paths: |
| 780 | try: |
| 781 | importer = self._sys_path_importer(entry) |
| 782 | except ImportError: |
| 783 | continue |
| 784 | loader = importer.find_module(name) |
| 785 | if loader: |
| 786 | return loader |
| 787 | else: |
| 788 | raise ImportError("No module named %s" % name) |
| 789 | |
| 790 | def module_from_cache(self, name): |
| 791 | """Try to return the named module from sys.modules. |
| 792 | |
| 793 | Return False if the module is not in the cache. |
| 794 | """ |
| 795 | if name in sys.modules: |
| 796 | return sys.modules[name] |
| 797 | else: |
| 798 | return False |
| 799 | |
| 800 | def post_import(self, module): |
| 801 | """Perform any desired post-import processing on the module.""" |
| 802 | return module |
| 803 | |
| 804 | def _import_module(self, name, path=None): |
| 805 | """Import the specified module with no handling of parent modules. |
| 806 | |
| 807 | If None is set for a value in sys.modules (to signify that a relative |
| 808 | import was attempted and failed) then ImportError is raised. |
| 809 | |
| 810 | """ |
| 811 | cached_module = self.module_from_cache(name) |
| 812 | if cached_module is not False: |
| 813 | if cached_module is None: |
| 814 | raise ImportError("relative import redirect") |
| 815 | else: |
| 816 | return cached_module |
| 817 | try: |
| 818 | # Attempt to find a loader on sys.meta_path. |
| 819 | loader = self._search_meta_path(name, path) |
| 820 | except ImportError: |
| 821 | # sys.meta_path search failed. Attempt to find a loader on |
| 822 | # sys.path. If this fails then module cannot be found. |
| 823 | loader = self._search_std_path(name, path) |
| 824 | # A loader was found. It is the loader's responsibility to have put an |
| 825 | # entry in sys.modules. |
| 826 | module = self.post_import(loader.load_module(name)) |
| 827 | # 'module' could be something like None. |
| 828 | if not hasattr(module, '__name__'): |
| 829 | return module |
| 830 | # Set __package__. |
| 831 | if not hasattr(module, '__package__') or module.__package__ is None: |
| 832 | if hasattr(module, '__path__'): |
| 833 | module.__package__ = module.__name__ |
| 834 | elif '.' in module.__name__: |
| 835 | pkg_name = module.__name__.rsplit('.', 1)[0] |
| 836 | module.__package__ = pkg_name |
| 837 | else: |
| 838 | module.__package__ = None |
| 839 | return module |
| 840 | |
| 841 | |
| 842 | def _import_full_module(self, name): |
| 843 | """Import a module and set it on its parent if needed.""" |
| 844 | path_list = None |
| 845 | parent_name = name.rsplit('.', 1)[0] |
| 846 | parent = None |
| 847 | if parent_name != name: |
| 848 | parent = sys.modules[parent_name] |
| 849 | try: |
| 850 | path_list = parent.__path__ |
| 851 | except AttributeError: |
| 852 | pass |
| 853 | self._import_module(name, path_list) |
| 854 | module = sys.modules[name] |
| 855 | if parent: |
| 856 | tail = name.rsplit('.', 1)[-1] |
| 857 | setattr(parent, tail, module) |
| 858 | |
| 859 | def _find_package(self, name, has_path): |
| 860 | """Return the package that the caller is in or None.""" |
| 861 | if has_path: |
| 862 | return name |
| 863 | elif '.' in name: |
| 864 | return name.rsplit('.', 1)[0] |
| 865 | else: |
| 866 | return None |
| 867 | |
| 868 | @staticmethod |
| 869 | def _resolve_name(name, package, level): |
| 870 | """Return the absolute name of the module to be imported.""" |
| 871 | level -= 1 |
| 872 | try: |
| 873 | if package.count('.') < level: |
| 874 | raise ValueError("attempted relative import beyond top-level " |
| 875 | "package") |
| 876 | except AttributeError: |
| 877 | raise ValueError("__package__ not set to a string") |
| 878 | base = package.rsplit('.', level)[0] |
| 879 | if name: |
| 880 | return "{0}.{1}".format(base, name) |
| 881 | else: |
| 882 | return base |
| 883 | |
| 884 | def _return_module(self, absolute_name, relative_name, fromlist): |
| 885 | """Return the proper module based on what module was requested (and its |
| 886 | absolute module name), who is requesting it, and whether any specific |
| 887 | attributes were specified. |
| 888 | |
| 889 | The semantics of this method revolve around 'fromlist'. When it is |
| 890 | empty, the module up to the first dot is to be returned. When the |
| 891 | module being requested is an absolute name this is simple (and |
| 892 | relative_name is an empty string). But if the requested module was |
| 893 | a relative import (as signaled by relative_name having a non-false |
| 894 | value), then the name up to the first dot in the relative name resolved |
| 895 | to an absolute name is to be returned. |
| 896 | |
| 897 | When fromlist is not empty and the module being imported is a package, |
| 898 | then the values |
| 899 | in fromlist need to be checked for. If a value is not a pre-existing |
| 900 | attribute a relative import is attempted. If it fails then suppressed |
| 901 | the failure silently. |
| 902 | |
| 903 | """ |
| 904 | if not fromlist: |
| 905 | if relative_name: |
| 906 | absolute_base = absolute_name.rpartition(relative_name)[0] |
| 907 | relative_head = relative_name.split('.', 1)[0] |
| 908 | to_return = absolute_base + relative_head |
| 909 | else: |
| 910 | to_return = absolute_name.split('.', 1)[0] |
| 911 | return sys.modules[to_return] |
| 912 | # When fromlist is not empty, return the actual module specified in |
| 913 | # the import. |
| 914 | else: |
| 915 | module = sys.modules[absolute_name] |
| 916 | if hasattr(module, '__path__') and hasattr(module, '__name__'): |
| 917 | # When fromlist has a value and the imported module is a |
| 918 | # package, then if a name in fromlist is not found as an |
| 919 | # attribute on module, try a relative import to find it. |
| 920 | # Failure is fine and the exception is suppressed. |
| 921 | check_for = list(fromlist) |
| 922 | if '*' in check_for and hasattr(module, '__all__'): |
| 923 | check_for.extend(module.__all__) |
| 924 | for item in check_for: |
| 925 | if item == '*': |
| 926 | continue |
| 927 | if not hasattr(module, item): |
| 928 | resolved_name = self._resolve_name(item, |
| 929 | module.__name__, 1) |
| 930 | try: |
| 931 | self._import_full_module(resolved_name) |
| 932 | except ImportError: |
| 933 | pass |
| 934 | return module |
| 935 | |
| 936 | def __call__(self, name, globals={}, locals={}, fromlist=[], level=0): |
| 937 | """Import a module. |
| 938 | |
| 939 | The 'name' argument is the name of the module to be imported (e.g., |
| 940 | 'foo' in ``import foo`` or ``from foo import ...``). |
| 941 | |
| 942 | 'globals' and 'locals' are the global and local namespace dictionaries |
| 943 | of the module where the import statement appears. 'globals' is used to |
| 944 | introspect the __path__ and __name__ attributes of the module making |
| 945 | the call. 'local's is ignored. |
| 946 | |
| 947 | 'fromlist' lists any specific objects that are to eventually be put |
| 948 | into the namespace (e.g., ``from for.bar import baz`` would have 'baz' |
| 949 | in the fromlist, and this includes '*'). An entry of '*' will lead to |
| 950 | a check for __all__ being defined on the module. If it is defined then |
| 951 | the values in __all__ will be checked to make sure that all values are |
| 952 | attributes on the module, attempting a module import relative to 'name' |
| 953 | to set that attribute. |
| 954 | |
| 955 | When 'name' is a dotted name, there are two different situations to |
| 956 | consider for the return value. One is when the fromlist is empty. |
| 957 | In this situation the import statement imports and returns the name up |
| 958 | to the first dot. All subsequent names are imported but set as |
| 959 | attributes as needed on parent modules. When fromlist is not empty |
| 960 | then the module represented by the full dotted name is returned. |
| 961 | |
| 962 | 'level' represents possible relative imports. |
| 963 | A value of 0 is for absolute module names. Any positive value |
| 964 | represents the number of dots listed in the relative import statement |
| 965 | (e.g. has a value of 2 for ``from .. import foo``). |
| 966 | |
| 967 | """ |
| 968 | if not name and level < 1: |
| 969 | raise ValueError("Empty module name") |
| 970 | is_pkg = True if '__path__' in globals else False |
| 971 | caller_name = globals.get('__name__') |
| 972 | package = globals.get('__package__') |
| 973 | if caller_name and not package: |
| 974 | package = self._find_package(caller_name, '__path__' in globals) |
| 975 | if package and package not in sys.modules: |
| 976 | if not hasattr(package, 'rsplit'): |
| 977 | raise ValueError("__package__ not set to a string") |
| 978 | msg = ("Parent module {0!r} not loaded, " |
| 979 | "cannot perform relative import") |
| 980 | raise SystemError(msg.format(package)) |
| 981 | with ImportLockContext(): |
| 982 | if level: |
| 983 | imported_name = self._resolve_name(name, package, level) |
| 984 | else: |
| 985 | imported_name = name |
| 986 | parent_name = imported_name.rsplit('.', 1)[0] |
| 987 | if parent_name != imported_name and parent_name not in sys.modules: |
| 988 | self.__call__(parent_name, level=0) |
| 989 | # This call will also handle setting the attribute on the |
| 990 | # package. |
| 991 | self._import_full_module(imported_name) |
| 992 | relative_name = '' if imported_name == name else name |
| 993 | return self._return_module(imported_name, relative_name, fromlist) |
| 994 | |
| 995 | # XXX Eventually replace with a proper __all__ value (i.e., don't expose os |
| 996 | # replacements but do expose _ExtensionFileLoader, etc. for testing). |
| 997 | __all__ = [obj for obj in globals().keys() if not obj.startswith('__')] |