1 #!/usr/bin/env python 2 3 """ 4 Import logic. 5 6 Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013, 7 2014, 2015, 2016 Paul Boddie <paul@boddie.org.uk> 8 9 This program is free software; you can redistribute it and/or modify it under 10 the terms of the GNU General Public License as published by the Free Software 11 Foundation; either version 3 of the License, or (at your option) any later 12 version. 13 14 This program is distributed in the hope that it will be useful, but WITHOUT 15 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS 16 FOR A PARTICULAR PURPOSE. See the GNU General Public License for more 17 details. 18 19 You should have received a copy of the GNU General Public License along with 20 this program. If not, see <http://www.gnu.org/licenses/>. 21 """ 22 23 from errors import ProgramError 24 from os.path import exists, extsep, getmtime, join 25 from os import listdir, makedirs, remove 26 from common import init_item, readfile, writefile 27 from modules import CachedModule 28 from referencing import Reference 29 import inspector 30 import sys 31 32 class Importer: 33 34 "An import machine, searching for and loading modules." 35 36 def __init__(self, path, cache=None, verbose=False): 37 38 """ 39 Initialise the importer with the given search 'path' - a list of 40 directories to search for Python modules. 41 42 The optional 'cache' should be the name of a directory used to store 43 cached module information. 44 45 The optional 'verbose' parameter causes output concerning the activities 46 of the object to be produced if set to a true value (not the default). 47 """ 48 49 self.path = path 50 self.cache = cache 51 self.verbose = verbose 52 53 # Module importing queue, required modules, removed modules and active 54 # modules in the final program. 55 56 self.to_import = set() 57 self.required = set(["__main__"]) 58 self.removed = {} 59 self.modules = {} 60 61 # Module relationships and invalidated cached modules. 62 63 self.accessing_modules = {} 64 self.invalidated = set() 65 66 # Basic program information. 67 68 self.objects = {} 69 self.classes = {} 70 self.function_parameters = {} 71 self.function_defaults = {} 72 self.function_locals = {} 73 self.function_targets = {} 74 self.function_arguments = {} 75 76 # Unresolved names. 77 78 self.missing = set() 79 80 # Derived information. 81 82 self.subclasses = {} 83 84 # Attributes of different object types. 85 86 self.all_class_attrs = {} 87 self.all_instance_attrs = {} 88 self.all_instance_attr_constants = {} 89 self.all_combined_attrs = {} 90 self.all_module_attrs = {} 91 self.all_shadowed_attrs = {} 92 93 # References to external names and aliases within program units. 94 95 self.all_name_references = {} 96 self.all_initialised_names = {} 97 self.all_aliased_names = {} 98 99 # General attribute accesses. 100 101 self.all_attr_accesses = {} 102 self.all_const_accesses = {} 103 self.all_attr_access_modifiers = {} 104 105 # Constant literals and values. 106 107 self.all_constants = {} 108 self.all_constant_values = {} 109 110 self.make_cache() 111 112 def make_cache(self): 113 if self.cache and not exists(self.cache): 114 makedirs(self.cache) 115 116 def check_cache(self, details): 117 118 """ 119 Check whether the cache applies for the given 'details', invalidating it 120 if it does not. 121 """ 122 123 recorded_details = self.get_cache_details() 124 125 if recorded_details != details: 126 self.remove_cache() 127 128 writefile(self.get_cache_details_filename(), details) 129 130 def get_cache_details_filename(self): 131 132 "Return the filename for the cache details." 133 134 return join(self.cache, "$details") 135 136 def get_cache_details(self): 137 138 "Return details of the cache." 139 140 details_filename = self.get_cache_details_filename() 141 142 if not exists(details_filename): 143 return None 144 else: 145 return readfile(details_filename) 146 147 def remove_cache(self): 148 149 "Remove the contents of the cache." 150 151 for filename in listdir(self.cache): 152 remove(join(self.cache, filename)) 153 154 def to_cache(self): 155 156 "Write modules to the cache." 157 158 if self.cache: 159 for module_name, module in self.modules.items(): 160 module.to_cache(join(self.cache, module_name)) 161 162 # Object retrieval and storage. 163 164 def get_object(self, name): 165 166 """ 167 Return a reference for the given 'name' or None if no such object 168 exists. 169 """ 170 171 return self.objects.get(name) 172 173 def set_object(self, name, value=None): 174 175 "Set the object with the given 'name' and the given 'value'." 176 177 if isinstance(value, Reference): 178 ref = value.alias(name) 179 else: 180 ref = Reference(value, name) 181 182 self.objects[name] = ref 183 184 # Identification of both stored object names and name references. 185 186 def identify(self, name): 187 188 "Identify 'name' using stored object and external name records." 189 190 return self.objects.get(name) or self.all_name_references.get(name) 191 192 # Indirect object retrieval. 193 194 def get_attributes(self, ref, attrname): 195 196 """ 197 Return attributes provided by 'ref' for 'attrname'. Class attributes 198 may be provided by instances. 199 """ 200 201 kind = ref.get_kind() 202 if kind == "<class>": 203 ref = self.get_class_attribute(ref.get_origin(), attrname) 204 return ref and set([ref]) or set() 205 elif kind == "<instance>": 206 return self.get_combined_attributes(ref.get_origin(), attrname) 207 elif kind == "<module>": 208 ref = self.get_module_attribute(ref.get_origin(), attrname) 209 return ref and set([ref]) or set() 210 else: 211 return set() 212 213 def get_class_attribute(self, object_type, attrname): 214 215 "Return from 'object_type' the details of class attribute 'attrname'." 216 217 attrs = self.all_class_attrs.get(object_type) 218 attr = attrs and attrs.get(attrname) 219 return attr and self.get_object(attr) 220 221 def get_instance_attributes(self, object_type, attrname): 222 223 """ 224 Return from 'object_type' the details of instance attribute 'attrname'. 225 """ 226 227 consts = self.all_instance_attr_constants.get(object_type) 228 attrs = set() 229 for attr in self.all_instance_attrs[object_type].get(attrname, []): 230 attrs.add(consts and consts.get(attrname) or Reference("<var>", attr)) 231 return attrs 232 233 def get_combined_attributes(self, object_type, attrname): 234 235 """ 236 Return from 'object_type' the details of class or instance attribute 237 'attrname'. 238 """ 239 240 ref = self.get_class_attribute(object_type, attrname) 241 refs = ref and set([ref]) or set() 242 refs.update(self.get_instance_attributes(object_type, attrname)) 243 return refs 244 245 def get_module_attribute(self, object_type, attrname): 246 247 "Return from 'object_type' the details of module attribute 'attrname'." 248 249 if attrname in self.all_module_attrs[object_type]: 250 return self.get_object("%s.%s" % (object_type, attrname)) 251 else: 252 return None 253 254 # Convenience methods for deducing which kind of object provided an 255 # attribute. 256 257 def get_attribute_provider(self, ref, attrname): 258 259 """ 260 Return the kind of provider of the attribute accessed via 'ref' using 261 'attrname'. 262 """ 263 264 kind = ref.get_kind() 265 266 if kind in ["<class>", "<module>"]: 267 return kind 268 else: 269 return self.get_instance_attribute_provider(ref.get_origin(), attrname) 270 271 def get_instance_attribute_provider(self, object_type, attrname): 272 273 """ 274 Return the kind of provider of the attribute accessed via an instance of 275 'object_type' using 'attrname'. 276 """ 277 278 if self.get_class_attribute(object_type, attrname): 279 return "<class>" 280 else: 281 return "<instance>" 282 283 # Module management. 284 285 def queue_module(self, name, accessor, required=False): 286 287 """ 288 Queue the module with the given 'name' for import from the given 289 'accessor' module. If 'required' is true (it is false by default), the 290 module will be required in the final program. 291 """ 292 293 if not self.modules.has_key(name): 294 self.to_import.add(name) 295 296 if required: 297 self.required.add(name) 298 299 init_item(self.accessing_modules, name, set) 300 self.accessing_modules[name].add(accessor.name) 301 302 def get_modules(self): 303 304 "Return all modules known to the importer." 305 306 return self.modules.values() 307 308 def get_module(self, name): 309 310 "Return the module with the given 'name'." 311 312 if not self.modules.has_key(name): 313 return None 314 315 return self.modules[name] 316 317 # Program operations. 318 319 def initialise(self, filename, reset=False): 320 321 """ 322 Initialise a program whose main module is 'filename', resetting the 323 cache if 'reset' is true. Return the main module. 324 """ 325 326 if reset: 327 self.remove_cache() 328 self.check_cache(filename) 329 330 # Load the program itself. 331 332 m = self.load_from_file(filename) 333 334 # Load any queued modules. 335 336 while self.to_import: 337 for name in list(self.to_import): # avoid mutation issue 338 self.load(name) 339 340 # Resolve dependencies between modules. 341 342 self.resolve() 343 344 # Record the type of all classes. 345 346 self.type_ref = self.get_object("__builtins__.type") 347 348 # Resolve dependencies within the program. 349 350 for module in self.modules.values(): 351 module.complete() 352 353 # Remove unneeded modules. 354 355 all_modules = self.modules.items() 356 357 for name, module in all_modules: 358 if name not in self.required: 359 module.unpropagate() 360 del self.modules[name] 361 self.removed[name] = module 362 363 # Collect redundant objects. 364 365 for module in self.removed.values(): 366 module.collect() 367 368 # Assert module objects where aliases have been removed. 369 370 for name in self.required: 371 if not self.objects.has_key(name): 372 self.objects[name] = Reference("<module>", name) 373 374 return m 375 376 def finalise(self): 377 378 """ 379 Finalise the inspected program, returning whether the program could be 380 finalised. 381 """ 382 383 if self.missing: 384 return False 385 386 self.finalise_classes() 387 self.to_cache() 388 self.set_class_types() 389 self.define_instantiators() 390 self.collect_constants() 391 392 return True 393 394 # Supporting operations. 395 396 def resolve(self): 397 398 "Resolve dependencies between modules." 399 400 self.waiting = {} 401 self.depends = {} 402 403 for module in self.modules.values(): 404 405 # Resolve all deferred references in each module. 406 407 for ref in module.deferred: 408 found = self.find_dependency(ref) 409 if not found: 410 self.missing.add((module.name, ref.get_origin())) 411 412 # Record the resolved names and identify required modules. 413 414 else: 415 # Find the providing module of this reference. 416 # Where definitive details of the origin cannot be found, 417 # identify the provider using the deferred reference. 418 # NOTE: This may need to test for static origins. 419 420 provider = self.get_module_provider(found.unresolved() and ref or found) 421 ref.mutate(found) 422 423 # Record any external dependency. 424 425 if provider and provider != module.name: 426 427 # Record the provider dependency. 428 429 module.required.add(provider) 430 self.accessing_modules[provider].add(module.name) 431 432 # Postpone any inclusion of the provider until this 433 # module becomes required. 434 435 if module.name not in self.required: 436 init_item(self.waiting, module.name, set) 437 self.waiting[module.name].add(provider) 438 439 # Make this module required in the accessing module. 440 441 elif provider not in self.required: 442 self.required.add(provider) 443 if self.verbose: 444 print >>sys.stderr, "Requiring", provider, "for", ref 445 446 # Record a module ordering dependency. 447 448 if not found.static() or self.uses_dynamic_callable(found): 449 init_item(self.depends, module.name, set) 450 self.depends[module.name].add(provider) 451 452 # Check modules again to see if they are now required and should now 453 # cause the inclusion of other modules providing objects to the program. 454 455 for module_name in self.waiting.keys(): 456 self.require_providers(module_name) 457 458 def require_providers(self, module_name): 459 460 """ 461 Test if 'module_name' is itself required and, if so, require modules 462 containing objects provided to the module. 463 """ 464 465 if module_name in self.required and self.waiting.has_key(module_name): 466 for provider in self.waiting[module_name]: 467 if provider not in self.required: 468 self.required.add(provider) 469 if self.verbose: 470 print >>sys.stderr, "Requiring", provider 471 self.require_providers(provider) 472 473 def uses_dynamic_callable(self, ref): 474 475 """ 476 Return whether 'ref' refers to a callable employing defaults that may 477 need initialising before the callable can be used. 478 """ 479 480 return ref.has_kind("<function>") and self.function_defaults.get(ref.get_origin()) or \ 481 ref.has_kind("<class>") and self.function_defaults.get("%s.__init__" % ref.get_origin()) 482 483 def order_modules(self): 484 485 "Produce a module initialisation ordering." 486 487 self.check_ordering() 488 489 module_names = self.modules.keys() 490 491 # Record the number of modules using or depending on each module. 492 493 usage = {} 494 495 for module_name in module_names: 496 usage[module_name] = 0 497 498 for module_name, depend_names in self.depends.items(): 499 if module_name in module_names: 500 for depend_name in depend_names: 501 if depend_name in module_names: 502 usage[depend_name] += 1 503 504 # Produce an ordering by obtaining exposed modules (required by modules 505 # already processed) and putting them at the start of the list. 506 507 ordered = [] 508 509 while usage: 510 for module_name, n in usage.items(): 511 if n == 0: 512 ordered.insert(0, module_name) 513 module_names = self.depends.get(module_name) 514 515 # Reduce usage of the referenced modules. 516 517 if module_names: 518 for name in module_names: 519 usage[name] -= 1 520 521 del usage[module_name] 522 523 ordered.remove("__main__") 524 ordered.append("__main__") 525 return ordered 526 527 def check_ordering(self): 528 529 "Check the ordering dependencies." 530 531 for module_name, modules in self.depends.items(): 532 for provider in modules: 533 if self.depends.has_key(provider) and module_name in self.depends[provider]: 534 raise ProgramError, "Modules %s and %s may not depend on each other for non-static objects." % (module_name, provider) 535 536 def find_dependency(self, ref): 537 538 "Find the ultimate dependency for 'ref'." 539 540 found = set() 541 while ref and ref.has_kind("<depends>") and not ref in found: 542 found.add(ref) 543 ref = self.identify(ref.get_origin()) 544 return ref 545 546 def get_module_provider(self, ref): 547 548 "Identify the provider of the given 'ref'." 549 550 for ancestor in ref.ancestors(): 551 if self.modules.has_key(ancestor): 552 return ancestor 553 return None 554 555 def finalise_classes(self): 556 557 "Finalise the class relationships and attributes." 558 559 self.derive_inherited_attrs() 560 self.derive_subclasses() 561 self.derive_shadowed_attrs() 562 563 def derive_inherited_attrs(self): 564 565 "Derive inherited attributes for classes throughout the program." 566 567 for name in self.classes.keys(): 568 self.propagate_attrs_for_class(name) 569 570 def propagate_attrs_for_class(self, name, visited=None): 571 572 "Propagate inherited attributes for class 'name'." 573 574 # Visit classes only once. 575 576 if self.all_combined_attrs.has_key(name): 577 return 578 579 visited = visited or [] 580 581 if name in visited: 582 raise ProgramError, "Class %s may not inherit from itself: %s -> %s." % (name, " -> ".join(visited), name) 583 584 visited.append(name) 585 586 class_attrs = {} 587 instance_attrs = {} 588 589 # Aggregate the attributes from base classes, recording the origins of 590 # applicable attributes. 591 592 for base in self.classes[name][::-1]: 593 594 # Get the identity of the class from the reference. 595 596 base = base.get_origin() 597 598 # Define the base class completely before continuing with this 599 # class. 600 601 self.propagate_attrs_for_class(base, visited) 602 class_attrs.update(self.all_class_attrs[base]) 603 604 # Instance attribute origins are combined if different. 605 606 for key, values in self.all_instance_attrs[base].items(): 607 init_item(instance_attrs, key, set) 608 instance_attrs[key].update(values) 609 610 # Class attributes override those defined earlier in the hierarchy. 611 612 class_attrs.update(self.all_class_attrs.get(name, {})) 613 614 # Instance attributes are merely added if not already defined. 615 616 for key in self.all_instance_attrs.get(name, []): 617 if not instance_attrs.has_key(key): 618 instance_attrs[key] = set(["%s.%s" % (name, key)]) 619 620 self.all_class_attrs[name] = class_attrs 621 self.all_instance_attrs[name] = instance_attrs 622 self.all_combined_attrs[name] = set(class_attrs.keys()).union(instance_attrs.keys()) 623 624 def derive_subclasses(self): 625 626 "Derive subclass details for classes." 627 628 for name, bases in self.classes.items(): 629 for base in bases: 630 631 # Get the identity of the class from the reference. 632 633 base = base.get_origin() 634 self.subclasses[base].add(name) 635 636 def derive_shadowed_attrs(self): 637 638 "Derive shadowed attributes for classes." 639 640 for name, attrs in self.all_instance_attrs.items(): 641 attrs = set(attrs.keys()).intersection(self.all_class_attrs[name].keys()) 642 if attrs: 643 self.all_shadowed_attrs[name] = attrs 644 645 def set_class_types(self): 646 647 "Set the type of each class." 648 649 for attrs in self.all_class_attrs.values(): 650 attrs["__class__"] = self.type_ref.get_origin() 651 652 def define_instantiators(self): 653 654 """ 655 Consolidate parameter and default details, incorporating initialiser 656 details to define instantiator signatures. 657 """ 658 659 for cls, attrs in self.all_class_attrs.items(): 660 initialiser = attrs["__init__"] 661 self.function_parameters[cls] = self.function_parameters[initialiser] 662 self.function_defaults[cls] = self.function_defaults[initialiser] 663 664 def collect_constants(self): 665 666 "Get constants from all active modules." 667 668 for module in self.modules.values(): 669 self.all_constants.update(module.constants) 670 671 # Import methods. 672 673 def find_in_path(self, name): 674 675 """ 676 Find the given module 'name' in the search path, returning None where no 677 such module could be found, or a 2-tuple from the 'find' method 678 otherwise. 679 """ 680 681 for d in self.path: 682 m = self.find(d, name) 683 if m: return m 684 return None 685 686 def find(self, d, name): 687 688 """ 689 In the directory 'd', find the given module 'name', where 'name' can 690 either refer to a single file module or to a package. Return None if the 691 'name' cannot be associated with either a file or a package directory, 692 or a 2-tuple from '_find_package' or '_find_module' otherwise. 693 """ 694 695 m = self._find_package(d, name) 696 if m: return m 697 m = self._find_module(d, name) 698 if m: return m 699 return None 700 701 def _find_module(self, d, name): 702 703 """ 704 In the directory 'd', find the given module 'name', returning None where 705 no suitable file exists in the directory, or a 2-tuple consisting of 706 None (indicating that no package directory is involved) and a filename 707 indicating the location of the module. 708 """ 709 710 name_py = name + extsep + "py" 711 filename = self._find_file(d, name_py) 712 if filename: 713 return None, filename 714 return None 715 716 def _find_package(self, d, name): 717 718 """ 719 In the directory 'd', find the given package 'name', returning None 720 where no suitable package directory exists, or a 2-tuple consisting of 721 a directory (indicating the location of the package directory itself) 722 and a filename indicating the location of the __init__.py module which 723 declares the package's top-level contents. 724 """ 725 726 filename = self._find_file(d, name) 727 if filename: 728 init_py = "__init__" + extsep + "py" 729 init_py_filename = self._find_file(filename, init_py) 730 if init_py_filename: 731 return filename, init_py_filename 732 return None 733 734 def _find_file(self, d, filename): 735 736 """ 737 Return the filename obtained when searching the directory 'd' for the 738 given 'filename', or None if no actual file exists for the filename. 739 """ 740 741 filename = join(d, filename) 742 if exists(filename): 743 return filename 744 else: 745 return None 746 747 def load(self, name): 748 749 """ 750 Load the module or package with the given 'name'. Return an object 751 referencing the loaded module or package, or None if no such module or 752 package exists. 753 """ 754 755 # Loaded modules are returned immediately. 756 # Modules may be known but not yet loading (having been registered as 757 # submodules), loading, loaded, or completely unknown. 758 759 module = self.get_module(name) 760 761 if module: 762 return self.modules[name] 763 764 # Otherwise, modules are loaded. 765 766 # Split the name into path components, and try to find the uppermost in 767 # the search path. 768 769 path = name.split(".") 770 path_so_far = [] 771 module = None 772 773 for p in path: 774 775 # Get the module's filesystem details. 776 777 if not path_so_far: 778 m = self.find_in_path(p) 779 elif d: 780 m = self.find(d, p) 781 else: 782 m = None 783 784 path_so_far.append(p) 785 module_name = ".".join(path_so_far) 786 787 # Return None if the module could not be located. 788 789 if not m: 790 if self.verbose: 791 print >>sys.stderr, "Not found (%s)" % name 792 return None 793 794 # Get the directory and module filename. 795 796 d, filename = m 797 798 # Get the module itself. 799 800 return self.load_from_file(filename, module_name) 801 802 def load_from_file(self, filename, module_name=None): 803 804 "Load the module from the given 'filename'." 805 806 if module_name is None: 807 module_name = "__main__" 808 809 module = self.modules.get(module_name) 810 811 if not module: 812 813 # Try to load from cache. 814 815 module = self.load_from_cache(filename, module_name) 816 if module: 817 return module 818 819 # If no cache entry exists, load from file. 820 821 module = inspector.InspectedModule(module_name, self) 822 self.add_module(module_name, module) 823 self.update_cache_validity(module) 824 825 self._load(module, module_name, lambda m: m.parse, filename) 826 827 return module 828 829 def update_cache_validity(self, module): 830 831 "Make 'module' valid in the cache, but invalidate accessing modules." 832 833 accessing = self.accessing_modules.get(module.name) 834 if accessing: 835 self.invalidated.update(accessing) 836 if module.name in self.invalidated: 837 self.invalidated.remove(module.name) 838 839 def source_is_new(self, filename, module_name): 840 841 "Return whether 'filename' is newer than the cached 'module_name'." 842 843 if self.cache: 844 cache_filename = join(self.cache, module_name) 845 return not exists(cache_filename) or \ 846 getmtime(filename) > getmtime(cache_filename) or \ 847 module_name in self.invalidated 848 else: 849 return True 850 851 def load_from_cache(self, filename, module_name): 852 853 "Return a module residing in the cache." 854 855 module = self.modules.get(module_name) 856 857 if not module and not self.source_is_new(filename, module_name): 858 module = CachedModule(module_name, self) 859 self.add_module(module_name, module) 860 861 filename = join(self.cache, module_name) 862 self._load(module, module_name, lambda m: m.from_cache, filename) 863 864 return module 865 866 def _load(self, module, module_name, fn, filename): 867 868 """ 869 Load 'module' for the given 'module_name', and with 'fn' performing an 870 invocation on the module with the given 'filename'. 871 """ 872 873 # Load the module. 874 875 if self.verbose: 876 print >>sys.stderr, module_name in self.required and "Required" or "Loading", module_name, "from", filename 877 fn(module)(filename) 878 879 # Add the module object if not already defined. 880 881 if not self.objects.has_key(module_name): 882 self.objects[module_name] = Reference("<module>", module_name) 883 884 def add_module(self, module_name, module): 885 886 """ 887 Return the module with the given 'module_name', adding a new module 888 object if one does not already exist. 889 """ 890 891 self.modules[module_name] = module 892 if module_name in self.to_import: 893 self.to_import.remove(module_name) 894 895 # vim: tabstop=4 expandtab shiftwidth=4