#!/usr/bin/env python  """ Inspect and obtain module structure.  Copyright (C) 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017,               2018, 2019 Paul Boddie <paul@boddie.org.uk>  This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3 of the License, or (at your option) any later version.  This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more details.  You should have received a copy of the GNU General Public License along with this program.  If not, see <http://www.gnu.org/licenses/>. """  from branching import BranchTracker from common import CommonModule, get_argnames, init_item, \                    predefined_constants, privileged_attributes from modules import BasicModule, CacheWritingModule, InspectionNaming from errors import InspectError from referencing import Reference from resolving import NameResolving from results import AccessRef, InstanceRef, InvocationRef, LiteralSequenceRef, \                     LocalNameRef, MultipleRef, NameRef, ResolvedNameRef, \                     Result, VariableRef import compiler import sys  class InspectedModule(BasicModule, CacheWritingModule, NameResolving, InspectionNaming):      "A module inspector."      def __init__(self, name, importer):          "Initialise the module with basic details."          BasicModule.__init__(self, name, importer)          self.in_class = False         self.in_conditional = False          # Accesses to global attributes.          self.global_attr_accesses = {}          # Usage tracking.          self.trackers = []         self.attr_accessor_branches = {}      def __repr__(self):         return "InspectedModule(%r, %r)" % (self.name, self.importer)      # Principal methods.      def parse(self, filename):          "Parse the file having the given 'filename'."          self.parse_file(filename)          # Inspect the module.          self.start_tracking_in_module()          # Detect and record imports and globals declared in the module.          self.process_structure(self.astnode)          # Set the class of the module after the definition has occurred.          ref = self.get_builtin("module")         self.set_name("__class__", ref)         self.set_name("__name__", self.get_constant("string", self.name).reference())         self.set_name("__file__", self.get_constant("string", filename).reference())          # Reserve a constant for the encoding.          if self.encoding:             self.get_constant("string", self.encoding)          # Get module-level attribute usage details.          self.stop_tracking_in_module()          # Collect external name references.          self.collect_names()      def complete(self):          "Complete the module inspection."          # Resolve names not definitively mapped to objects.          self.resolve()          # Propagate to the importer information needed in subsequent activities.          self.propagate()      # Accessory methods.      def collect_names(self):          "Collect the names used by each scope."          for path in self.names_used.keys():             self.collect_names_for_path(path)      def collect_names_for_path(self, path):          """         Collect the names used by the given 'path'. These are propagated to the         importer in advance of any dependency resolution.         """          names = self.names_used.get(path)         if not names:             return          in_function = self.function_locals.has_key(path)          for name in names:             if in_function and name in self.function_locals[path]:                 continue              key = "%s.%s" % (path, name)              # Find local definitions.              ref = self.get_resolved_object(key, True)             if ref:                 self.set_name_reference(key, ref)                 continue              # Find global.              ref = self.get_global(name)             if ref:                 self.set_name_reference(key, ref)                 continue              # Find presumed built-in definitions.              ref = self.get_builtin(name)             self.set_name_reference(key, ref)      def set_name_reference(self, path, ref):          "Map the given name 'path' to 'ref'."          self.importer.all_name_references[path] = self.name_references[path] = ref      # Module structure traversal.      def process_structure_node(self, n):          "Process the individual node 'n'."          path = self.get_namespace_path()          # Module global detection.          if isinstance(n, compiler.ast.Global):             self.process_global_node(n)          # Module import declarations.          elif isinstance(n, compiler.ast.From):             self.process_from_node(n)          elif isinstance(n, compiler.ast.Import):             self.process_import_node(n)          # Nodes using operator module functions.          elif isinstance(n, compiler.ast.Operator):             return self.process_operator_node(n)          elif isinstance(n, compiler.ast.AugAssign):             self.process_augassign_node(n)          elif isinstance(n, compiler.ast.Compare):             return self.process_compare_node(n)          elif isinstance(n, compiler.ast.Slice):             return self.process_slice_node(n)          elif isinstance(n, compiler.ast.Sliceobj):             return self.process_sliceobj_node(n)          elif isinstance(n, compiler.ast.Subscript):             return self.process_subscript_node(n)          # Namespaces within modules.          elif isinstance(n, compiler.ast.Class):             self.process_class_node(n)          elif isinstance(n, compiler.ast.Function):             self.process_function_node(n, n.name)          elif isinstance(n, compiler.ast.Lambda):             return self.process_lambda_node(n)          # Assignments.          elif isinstance(n, compiler.ast.Assign):              # Handle each assignment node.              for node in n.nodes:                 self.process_assignment_node(node, n.expr)          # Assignments within non-Assign nodes.          elif isinstance(n, compiler.ast.AssName):             raise InspectError("Name assignment appearing outside assignment statement.", path, n)          elif isinstance(n, compiler.ast.AssAttr):             raise InspectError("Attribute assignment appearing outside assignment statement.", path, n)          # Accesses.          elif isinstance(n, compiler.ast.Getattr):             return self.process_attribute_access(n)          # Name recording for later testing.          elif isinstance(n, compiler.ast.Name):             return self.process_name_node(n)          # Conditional statement tracking.          elif isinstance(n, compiler.ast.For):             self.process_for_node(n)          elif isinstance(n, compiler.ast.While):             self.process_while_node(n)          elif isinstance(n, compiler.ast.If):             self.process_if_node(n)          elif isinstance(n, (compiler.ast.And, compiler.ast.Or)):             return self.process_logical_node(n)          # Exception control-flow tracking.          elif isinstance(n, compiler.ast.TryExcept):             self.process_try_node(n)          elif isinstance(n, compiler.ast.TryFinally):             self.process_try_finally_node(n)          # Control-flow modification statements.          elif isinstance(n, compiler.ast.Break):             self.trackers[-1].suspend_broken_branch()          elif isinstance(n, compiler.ast.Continue):             self.trackers[-1].suspend_continuing_branch()          elif isinstance(n, compiler.ast.Raise):             self.process_structure(n)             self.trackers[-1].abandon_branch()          elif isinstance(n, compiler.ast.Return):             self.record_return_value(self.process_structure_node(n.value))             self.trackers[-1].abandon_returning_branch()          # Print statements.          elif isinstance(n, (compiler.ast.Print, compiler.ast.Printnl)):             self.process_print_node(n)          # Invocations.          elif isinstance(n, compiler.ast.CallFunc):             return self.process_invocation_node(n)          # Constant usage.          elif isinstance(n, compiler.ast.Const):             return self.get_literal_instance(n)          elif isinstance(n, compiler.ast.Dict):             return self.get_literal_instance(n, "dict")          elif isinstance(n, compiler.ast.List):             return self.get_literal_instance(n, "list")          elif isinstance(n, compiler.ast.Tuple):             return self.get_literal_instance(n, "tuple")          # All other nodes are processed depth-first.          else:             self.process_structure(n)          # By default, no expression details are returned.          return None      # Specific node handling.      def process_assignment_node(self, n, expr):          "Process the individual node 'n' to be assigned the contents of 'expr'."          # Names and attributes are assigned the entire expression.          if isinstance(n, compiler.ast.AssName):             if n.name == "self":                 raise InspectError("Redefinition of self is not allowed.", self.get_namespace_path(), n)              name_ref = expr and self.process_structure_node(expr)              # Name assignments populate either function namespaces or the             # general namespace hierarchy.              self.assign_general_local(n.name, name_ref)              # Record usage of the name.              self.record_name(n.name)          elif isinstance(n, compiler.ast.AssAttr):             if expr:                 expr = self.process_structure_node(expr)              in_assignment = self.in_assignment             self.in_assignment = True             self.process_attribute_access(n)             self.in_assignment = in_assignment          # Lists and tuples are matched against the expression and their         # items assigned to expression items.          elif isinstance(n, (compiler.ast.AssList, compiler.ast.AssTuple)):             self.process_assignment_node_items(n, expr)          # Slices and subscripts are permitted within assignment nodes.          elif isinstance(n, compiler.ast.Slice):             self.process_slice_node(n, expr)          elif isinstance(n, compiler.ast.Subscript):             self.process_subscript_node(n, expr)      def process_attribute_access(self, n):          "Process the given attribute access node 'n'."          path = self.get_namespace_path()          # Test for access to special privileged attributes.          if isinstance(n, compiler.ast.Getattr) and \            n.attrname in privileged_attributes and not n.privileged:              raise InspectError("Attribute %s is accessed by an unprivileged operation." %                                n.attrname, path, n)          # Obtain any completed chain and return the reference to it.          name_ref = self.process_attribute_chain(n)          if self.have_access_expression(n):             return name_ref          # Where the start of the chain of attributes has been reached, determine         # the complete access.          # Given a non-access node, this chain can be handled in its entirety,         # either being name-based and thus an access rooted on a name, or being         # based on some other node and thus an anonymous access of some kind.          # Start with the the full attribute chain.          remaining = self.attrs         attrnames = ".".join(remaining)          # If the accessor cannot be identified, or where attributes         # remain in an attribute chain, record the anonymous accesses.          if not isinstance(name_ref, NameRef): # includes ResolvedNameRef              init_item(self.attr_accesses, path, set)             self.attr_accesses[path].add(attrnames)              self.record_access_details(None, attrnames, self.in_assignment,                 self.in_invocation)             del self.attrs[0]             return          # Name-based accesses will handle the first attribute in a         # chain.          else:             attrname = remaining[0]              # Attribute assignments are used to identify instance attributes.              if isinstance(n, compiler.ast.AssAttr) and \                 self.in_class and self.in_function and n.expr.name == "self":                  self.set_instance_attr(attrname)              # Record attribute usage using any name local to this namespace,             # if assigned in the namespace, or using an external name             # (presently just globals within classes).              name = self.get_name_for_tracking(name_ref.name, name_ref)             tracker = self.trackers[-1]              immediate_access = len(self.attrs) == 1             assignment = immediate_access and isinstance(n, compiler.ast.AssAttr)              # Record global-based chains for subsequent resolution.              if name_ref.is_global_name():                 self.record_global_access_details(name, attrnames)              # Make sure the name is being tracked: global names will not             # already be initialised in a branch and must be added             # explicitly.              if not tracker.have_name(name):                 tracker.assign_names([name])                 if self.in_function:                     self.scope_globals[path].add(name)              # Record attribute usage in the tracker, and record the branch             # information for the access.              branches = tracker.use_attribute(name, attrname,                 self.in_invocation is not None, assignment)              if not branches:                 raise InspectError("Name %s is accessed using %s before an assignment." % (                     name, attrname), path, n)              self.record_branches_for_access(branches, name, attrnames)             access_number = self.record_access_details(name, attrnames,                 self.in_assignment, self.in_invocation)              del self.attrs[0]             return AccessRef(name, attrnames, access_number)      def process_class_node(self, n):          "Process the given class node 'n'."          path = self.get_namespace_path()          # To avoid notions of class "versions" where the same definition         # might be parameterised with different state and be referenced         # elsewhere (as base classes, for example), classes in functions or         # conditions are forbidden.          if self.in_function or self.in_conditional:             print >>sys.stderr, "In %s, class %s in function or conditional statement ignored." % (                 path, n.name)             return          # Resolve base classes.          bases = []          for base in n.bases:             base_class = self.get_class(base)              if not base_class:                 print >>sys.stderr, "In %s, class %s has unidentifiable base class: %s" % (                     path, n.name, base)                 return             else:                 bases.append(base_class)          # Detect conflicting definitions. Such definitions cause conflicts in         # the storage of namespace-related information.          class_name = self.get_object_path(n.name)         ref = self.get_object(class_name, defer=False)          if ref and ref.static():             raise InspectError("Multiple definitions for the same name are not permitted.", class_name, n)          # Record bases for the class and retain the class name.         # Note that the function class does not inherit from the object class.          if not bases and class_name != "__builtins__.core.object" and \                          class_name != "__builtins__.core.function":              ref = self.get_object("__builtins__.object")             bases.append(ref)          self.importer.classes[class_name] = self.classes[class_name] = bases         self.importer.subclasses[class_name] = set()         self.scope_globals[class_name] = set()          # Set the definition before entering the namespace rather than         # afterwards because methods may reference it. In normal Python,         # a class is not accessible until the definition is complete, but         # methods can generally reference it since upon being called the         # class will already exist.          self.set_definition(n.name, "<class>")          in_class = self.in_class         self.in_class = class_name         self.set_instance_attr("__class__", Reference("<class>", class_name))         self.enter_namespace(n.name)          # Do not provide the special instantiator attributes on the function         # class. Function instances provide these attributes.          if class_name != "__builtins__.core.function":              self.set_name("__fn__") # special instantiator attribute             self.set_name("__args__") # special instantiator attribute          # Provide leafname, parent and context attributes.          parent, leafname = class_name.rsplit(".", 1)         self.set_name("__name__", self.get_constant("string", leafname).reference())          if class_name != "__builtins__.core.function":             self.set_name("__parent__")          self.process_structure_node(n.code)         self.exit_namespace()         self.in_class = in_class      def process_from_node(self, n):          "Process the given node 'n', importing from another module."          path = self.get_namespace_path()          module_name, names = self.get_module_name(n)         if module_name == self.name:             raise InspectError("Cannot import from the current module.", path, n)          self.queue_module(module_name)          # Attempt to obtain the referenced objects.          for name, alias in n.names:             if name == "*":                 raise InspectError("Only explicitly specified names can be imported from modules.", path, n)              # Explicit names.              ref = self.import_name_from_module(name, module_name)             value = ResolvedNameRef(alias or name, ref)             self.set_general_local(alias or name, value)      def process_function_node(self, n, name):          """         Process the given function or lambda node 'n' with the given 'name'.         """          is_lambda = isinstance(n, compiler.ast.Lambda)          # Where a function is declared conditionally, use a separate name for         # the definition, and assign the definition to the stated name.          if (self.in_conditional or self.in_function) and not is_lambda:             original_name = name             name = self.get_lambda_name()         else:             original_name = None          # Detect conflicting definitions. Such definitions cause conflicts in         # the storage of namespace-related information.          function_name = self.get_object_path(name)         ref = self.get_object(function_name, defer=False)          if ref and ref.static():             raise InspectError("Multiple definitions for the same name are not permitted.", function_name, n)          # Initialise argument and local records.          argnames = get_argnames(n.argnames)         is_method = self.in_class and not self.in_function          # Remove explicit "self" from method parameters.          if is_method and argnames and argnames[0] == "self":             del argnames[0]          # Convert .name entries in the parameters, provided this is a method.          l = []         attr_initialisers = []          for argname in argnames:             if argname[0] == ".":                 if not is_method:                     raise InspectError("Attribute initialisers are only allowed amongst method parameters.", function_name, n)                  argname = argname[1:]                 attr_initialisers.append(argname)              if argname in l:                 raise InspectError("Argument name %s is repeated." % argname, function_name, n)              l.append(argname)          argnames = l          # Copy and propagate the parameters.          self.importer.function_parameters[function_name] = \             self.function_parameters[function_name] = argnames[:]          self.importer.function_attr_initialisers[function_name] = \             self.function_attr_initialisers[function_name] = attr_initialisers          # Define all arguments/parameters in the local namespace.          locals = \             self.importer.function_locals[function_name] = \             self.function_locals[function_name] = {}          # Insert "self" into method locals.          if is_method:             argnames.insert(0, "self")          # Define "self" in terms of the class if in a method.         # This does not diminish the need for type-narrowing in the deducer.          if argnames:             if self.in_class and not self.in_function and argnames[0] == "self":                 locals[argnames[0]] = Reference("<instance>", self.in_class)             else:                 locals[argnames[0]] = Reference("<var>")          for argname in argnames[1:]:             locals[argname] = Reference("<var>")          globals = self.scope_globals[function_name] = set()          # Process the defaults.          defaults = self.importer.function_defaults[function_name] = \                    self.function_defaults[function_name] = []          for argname, default in compiler.ast.get_defaults(n):             if argname[0] == ".":                 argname = argname[1:]              if default:                  # Obtain any reference for the default.                  name_ref = self.process_structure_node(default)                 defaults.append((argname, name_ref.is_name() and name_ref.reference() or Reference("<var>")))          # Reset conditional tracking to focus on the function contents.          in_conditional = self.in_conditional         self.in_conditional = False          in_function = self.in_function         self.in_function = function_name          self.enter_namespace(name)          # Define a leafname attribute value for the function instance.          ref = self.get_builtin_class("string")         self.reserve_constant(function_name, name, ref.get_origin())          # Track attribute usage within the namespace.          path = self.get_namespace_path()         self.start_tracking(locals)          # Establish attributes for .name entries, provided this is a method.          for argname in attr_initialisers:             self.process_assignment_node(                     compiler.ast.AssAttr(compiler.ast.Name("self"), argname, "OP_ASSIGN"),                     compiler.ast.Name(argname))          self.process_structure_node(n.code)         returns_value = self.stop_tracking()          # Record any null result.          is_initialiser = is_method and name == "__init__"          if not returns_value and not is_initialiser:             self.record_return_value(ResolvedNameRef("None", self.get_builtin("None")))          # Exit to the parent.          self.exit_namespace()          # Update flags.          self.in_function = in_function         self.in_conditional = in_conditional          # Define the function using the appropriate name.          self.set_definition(name, "<function>")          # Where a function is set conditionally, assign the name.          if original_name:             self.process_assignment_for_object(original_name, compiler.ast.Name(name))      def process_global_node(self, n):          """         Process the given "global" node 'n'.         """          path = self.get_namespace_path()          if path != self.name:             self.scope_globals[path].update(n.names)      def process_if_node(self, n):          """         Process the given "if" node 'n'.         """          tracker = self.trackers[-1]         tracker.new_branchpoint()          for test, body in n.tests:             self.process_structure_node(test)              tracker.new_branch()              in_conditional = self.in_conditional             self.in_conditional = True             self.process_structure_node(body)             self.in_conditional = in_conditional              tracker.shelve_branch()          # Maintain a branch for the else clause.          tracker.new_branch()         if n.else_:             self.process_structure_node(n.else_)         tracker.shelve_branch()          tracker.merge_branches()      def process_import_node(self, n):          "Process the given import node 'n'."          path = self.get_namespace_path()          # Load the mentioned module.          for name, alias in n.names:             if name == self.name:                 raise InspectError("Cannot import the current module.", path, n)              self.set_module(alias or name.split(".")[-1], name)             self.queue_module(name, True)      def process_invocation_node(self, n):          "Process the given invocation node 'n'."          path = self.get_namespace_path()          in_invocation = self.in_invocation         self.in_invocation = None          # Process the arguments.          keywords = set()          for arg in n.args:             self.process_structure_node(arg)             if isinstance(arg, compiler.ast.Keyword):                 keywords.add(arg.name)          keywords = list(keywords)         keywords.sort()          # Communicate to the invocation target expression that it forms the         # target of an invocation, potentially affecting attribute accesses.          self.in_invocation = len(n.args), keywords          # Process the expression, obtaining any identified reference.          name_ref = self.process_structure_node(n.node)         self.in_invocation = in_invocation          # Detect class invocations.          if isinstance(name_ref, ResolvedNameRef) and name_ref.has_kind("<class>"):             return InstanceRef(name_ref.reference().instance_of())          elif isinstance(name_ref, (NameRef, AccessRef)):             return InvocationRef(name_ref)          # Provide a general reference to indicate that something is produced         # by the invocation, useful for retaining assignment expression         # details.          return VariableRef()      def process_lambda_node(self, n):          "Process the given lambda node 'n'."          name = self.get_lambda_name()         self.process_function_node(n, name)          origin = self.get_object_path(name)          if self.function_defaults.get(origin):             return None         else:             return ResolvedNameRef(name, Reference("<function>", origin))      def process_logical_node(self, n):          "Process the given operator node 'n'."          return self.process_operator_chain(n.nodes)      def process_name_node(self, n):          "Process the given name node 'n'."          path = self.get_namespace_path()          # Find predefined constant names before anything else.          if n.name in predefined_constants:             ref = self.get_builtin(n.name)             value = ResolvedNameRef(n.name, ref)             return value          # Special names that have already been identified.          if n.name.startswith("$"):             value = self.get_special(n.name)             if value:                 return value          # Special case for operator functions introduced through code         # transformations.          if n.name.startswith("$op"):              # Obtain the location of the actual function defined in the operator             # package.              op = n.name[len("$op"):]              # Attempt to get a reference.              ref = self.import_name_from_module(op, "operator")              # Record the imported name and provide the resolved name reference.              value = ResolvedNameRef(n.name, ref)             self.set_special(n.name, value)             return value          # Special case for sequence length testing.          elif n.name.startswith("$seq"):             op = n.name[len("$seq"):]             ref = self.import_name_from_module(op, "__builtins__.sequence")             value = ResolvedNameRef(n.name, ref)             self.set_special(n.name, value)             return value          # Special case for print operations.          elif n.name.startswith("$print"):              # Attempt to get a reference.              ref = self.get_builtin("print_")              # Record the imported name and provide the resolved name reference.              value = ResolvedNameRef(n.name, ref)             self.set_special(n.name, value)             return value          # Test for self usage, which is only allowed in methods.          if n.name == "self" and not (self.in_function and self.in_class):             raise InspectError("Use of self is only allowed in methods.", path, n)          # Record usage of the name.          self.record_name(n.name)          # Search for unknown names in non-function scopes immediately.         # Temporary names should not be re-used between scopes.         # External names in functions are resolved later.          ref = not n.name.startswith("$t") and self.find_name(n.name) or None          if ref:             self.record_name_access(n.name, True)             return ResolvedNameRef(n.name, ref, is_global=True)          # Explicitly-declared global names.          elif self.in_function and n.name in self.scope_globals[path]:             self.record_name_access(n.name, True)             return NameRef(n.name, is_global=True)          # Examine other names.          else:              # Check local names.              access_number = self.record_name_access(n.name)              # Local name.              if access_number is not None:                 return LocalNameRef(n.name, access_number)              # Possible global or built-in name.              else:                 self.record_name_access(n.name, True)                 return NameRef(n.name, is_global=True)      def record_name_access(self, name, is_global=False):          """         Record an access involving 'name' if the name is being tracked, using         'is_global' to indicate whether the name is global.         """          name = self.get_name_for_tracking(name, is_global=is_global)         branches = self.trackers[-1].tracking_name(name)         if branches:             self.record_branches_for_access(branches, name, None)             return self.record_access_details(name, None, self.in_assignment,                                               self.in_invocation)         return None      def process_operator_chain(self, nodes):          """         Process the given chain of 'nodes', processing each node or item.         Each node starts a new conditional region, effectively making a deeply-         nested collection of if-like statements.         """          results = []          tracker = self.trackers[-1]          for item in nodes:             tracker.new_branchpoint()             tracker.new_branch()             result = self.process_structure_node(item)             if result:                 results.append(result)          for item in nodes[:-1]:             tracker.shelve_branch()             tracker.new_branch()             tracker.shelve_branch()             tracker.merge_branches()          tracker.shelve_branch()         tracker.merge_branches()          return MultipleRef(results)      def process_try_node(self, n):          """         Process the given "try...except" node 'n'.         """          self.record_exception_handler()          tracker = self.trackers[-1]         tracker.new_branchpoint()          self.process_structure_node(n.body)          for name, var, handler in n.handlers:             if name is not None:                 self.process_structure_node(name)              # Any abandoned branches from the body can now be resumed in a new             # branch.              tracker.resume_abandoned_branches()              # Establish the local for the handler.              if var is not None:                 self.process_assignment_node(var, None)             if handler is not None:                 self.process_structure_node(handler)              tracker.shelve_branch()          # The else clause maintains the usage from the body but without the         # abandoned branches since they would never lead to the else clause         # being executed.          if n.else_:             tracker.new_branch()             self.process_structure_node(n.else_)             tracker.shelve_branch()          # Without an else clause, a null branch propagates the successful         # outcome.          else:             tracker.new_branch()             tracker.shelve_branch()          tracker.merge_branches()      def process_try_finally_node(self, n):          """         Process the given "try...finally" node 'n'.         """          self.record_exception_handler()          tracker = self.trackers[-1]         self.process_structure_node(n.body)          # Any abandoned branches from the body can now be resumed.          branches = tracker.resume_all_abandoned_branches()         self.process_structure_node(n.final)          # At the end of the finally clause, abandoned branches are discarded.          tracker.restore_active_branches(branches)      def process_while_node(self, n):          "Process the given while node 'n'."          tracker = self.trackers[-1]         tracker.new_branchpoint(loop_node=True)          # Evaluate any test or iterator outside the loop.          self.process_structure_node(n.test)          # Propagate attribute usage to branches.          tracker.new_branch(loop_node=True)          # Enter the loop.          in_conditional = self.in_conditional         self.in_conditional = True         self.process_structure_node(n.body)         self.in_conditional = in_conditional          # Continuing branches are resumed before any test.          tracker.resume_continuing_branches()          # Evaluate any continuation test within the body.          self.process_structure_node(n.test)          tracker.shelve_branch(loop_node=True)          # Support the non-looping condition.          tracker.new_branch()         tracker.shelve_branch()          tracker.merge_branches()          # Evaluate any else clause outside branches.          if n.else_:             self.process_structure_node(n.else_)          # Connect broken branches to the code after any loop.          tracker.resume_broken_branches()      # Branch tracking methods.      def start_tracking(self, names):          """         Start tracking attribute usage for names in the current namespace,         immediately registering the given 'names'.         """          path = self.get_namespace_path()         parent = self.trackers[-1]         tracker = BranchTracker()         self.trackers.append(tracker)          # Record the given names established as new branches.          tracker.assign_names(names)      def assign_name(self, name, name_ref):          "Assign to 'name' the given 'name_ref' in the current namespace."          name = self.get_name_for_tracking(name)         self.trackers[-1].assign_names([name], [name_ref])      def stop_tracking(self):          """         Stop tracking attribute usage, recording computed usage for the current         namespace. Indicate whether a value is always returned from the         namespace.         """          path = self.get_namespace_path()         tracker = self.trackers.pop()         self.record_assignments_for_access(tracker)          self.attr_usage[path] = tracker.get_all_usage()         self.name_initialisers[path] = tracker.get_all_values()          return tracker.returns_value()      def start_tracking_in_module(self):          "Start tracking attribute usage in the module."          tracker = BranchTracker()         self.trackers.append(tracker)      def stop_tracking_in_module(self):          "Stop tracking attribute usage in the module."          tracker = self.trackers[0]         self.record_assignments_for_access(tracker)         self.attr_usage[self.name] = tracker.get_all_usage()         self.name_initialisers[self.name] = tracker.get_all_values()      def record_assignments_for_access(self, tracker):          """         For the current path, use the given 'tracker' to record assignment         version information for attribute accesses.         """          path = self.get_path_for_access()          if not self.attr_accessor_branches.has_key(path):             return          init_item(self.attr_accessors, path, dict)         attr_accessors = self.attr_accessors[path]          # Obtain the branches applying during each access.          for access, all_branches in self.attr_accessor_branches[path].items():             name, attrnames = access             init_item(attr_accessors, access, list)              # Obtain the assignments applying to each branch.              for branches in all_branches:                 positions = tracker.get_assignment_positions_for_branches(name, branches)                  # Detect missing name information.                  if None in positions:                     globals = self.global_attr_accesses.get(path)                     accesses = globals and globals.get(name)                     if not accesses:                         print >>sys.stderr, "In %s, %s may not be defined when used." % (                             self.get_namespace_path(), name)                     positions.remove(None)                  attr_accessors[access].append(positions)      def record_branches_for_access(self, branches, name, attrnames):          """         Record the given 'branches' for an access involving the given 'name' and         'attrnames'.         """          access = name, attrnames         path = self.get_path_for_access()          init_item(self.attr_accessor_branches, path, dict)         attr_accessor_branches = self.attr_accessor_branches[path]          init_item(attr_accessor_branches, access, list)         attr_accessor_branches[access].append(branches)      def record_access_details(self, name, attrnames, assignment, invocation):          """         For the given 'name' and 'attrnames', record an access indicating         whether an 'assignment' or an 'invocation' is occurring.          These details correspond to accesses otherwise recorded by the attribute         accessor and attribute access dictionaries.         """          access = name, attrnames         path = self.get_path_for_access()          init_item(self.attr_access_modifiers, path, dict)         init_item(self.attr_access_modifiers[path], access, list)          access_number = len(self.attr_access_modifiers[path][access])         self.attr_access_modifiers[path][access].append((assignment, invocation))         return access_number      def record_global_access_details(self, name, attrnames):          """         Record details of a global access via the given 'name' involving the         indicated 'attrnames'.         """          path = self.get_namespace_path()          init_item(self.global_attr_accesses, path, dict)         init_item(self.global_attr_accesses[path], name, set)         self.global_attr_accesses[path][name].add(attrnames)      # Namespace modification.      def record_name(self, name):          "Record the use of 'name' in a namespace."          path = self.get_namespace_path()         init_item(self.names_used, path, set)         self.names_used[path].add(name)      def set_module(self, name, module_name):          """         Set a module in the current namespace using the given 'name' associated         with the corresponding 'module_name'.         """          if name:             self.set_general_local(name, Reference("<module>", module_name))      def set_definition(self, name, kind):          """         Set the definition having the given 'name' and 'kind'.          Definitions are set in the static namespace hierarchy, but they can also         be recorded for function locals.         """          if self.is_global(name):             print >>sys.stderr, "In %s, %s is defined as being global." % (                 self.get_namespace_path(), name)          path = self.get_object_path(name)         self.set_object(path, kind)          ref = self.get_object(path)         if ref.get_kind() == "<var>":             print >>sys.stderr, "In %s, %s is defined more than once." % (                 self.get_namespace_path(), name)          if not self.is_global(name) and self.in_function:             self.set_function_local(name, ref)      def set_function_local(self, name, ref=None):          "Set the local with the given 'name' and optional 'ref'."          path = self.get_namespace_path()         locals = self.function_locals[path]         used = self.names_used.get(path)          if not locals.has_key(name) and used and name in used:             raise InspectError("Name %s assigned locally but used previously." % name, path)          multiple = not ref or locals.has_key(name) and locals[name] != ref         locals[name] = multiple and Reference("<var>") or ref      def assign_general_local(self, name, name_ref):          """         Set for 'name' the given 'name_ref', recording the name for attribute         usage tracking.         """          self.set_general_local(name, name_ref)         self.assign_name(name, name_ref)      def set_general_local(self, name, value=None):          """         Set the 'name' with optional 'value' in any kind of local namespace,         where the 'value' should be a reference if specified.         """          init_value = self.get_initialising_value(value)          # Module global names.          if self.is_global(name):             path = self.get_global_path(name)             self.set_object(path, init_value)          # Function local names.          elif self.in_function:             self.set_function_local(name, init_value)          # Other namespaces (classes).          else:             self.set_name(name, init_value)      def set_name(self, name, ref=None):          "Attach the 'name' with optional 'ref' to the current namespace."          self.set_object(self.get_object_path(name), ref)      def set_instance_attr(self, name, ref=None):          """         Add an instance attribute of the given 'name' to the current class,         using the optional 'ref'.         """          self._set_instance_attr(self.in_class, name, ref)      def _set_instance_attr(self, path, name, ref=None):          init_item(self.instance_attrs, path, set)         self.instance_attrs[path].add(name)          if ref:             init_item(self.instance_attr_constants, path, dict)             self.instance_attr_constants[path][name] = ref      def get_initialising_value(self, value):          "Return a suitable initialiser reference for 'value'."          if isinstance(value, Result):             return value.reference()         else:             return value      # Static, program-relative naming.      def find_name(self, name):          """         Return the qualified name for the given 'name' used in the current         non-function namespace.         """          path = self.get_namespace_path()         ref = None          if not self.in_function and name not in predefined_constants:             if self.in_class:                 ref = self.get_object(self.get_object_path(name), False)             if not ref:                 ref = self.get_global_or_builtin(name)          return ref      def get_class(self, node):          """         Use the given 'node' to obtain the identity of a class. Return a         reference for the class. Unresolved dependencies are permitted and must         be resolved later.         """          ref = self._get_class(node)         return ref.has_kind(["<class>", "<depends>"]) and ref or None      def _get_class(self, node):          """         Use the given 'node' to find a class definition. Return a reference to         the class.         """          if isinstance(node, compiler.ast.Getattr):              # Obtain the identity of the access target.              ref = self._get_class(node.expr)              # Where the target is a class or module, obtain the identity of the             # attribute.              if ref.has_kind(["<function>", "<var>"]):                 return None             else:                 attrname = "%s.%s" % (ref.get_origin(), node.attrname)                 return self.get_object(attrname)          # Names can be module-level or built-in.          elif isinstance(node, compiler.ast.Name):              # Record usage of the name and attempt to identify it.              self.record_name(node.name)             return self.find_name(node.name)         else:             return None      def get_constant(self, name, value):          "Return a constant reference for the given type 'name' and 'value'."          ref = self.get_builtin_class(name)         return self.get_constant_reference(ref, value)      def get_literal_instance(self, n, name=None):          """         For node 'n', return a reference to an instance of 'name', or if 'name'         is not specified, deduce the type from the value.         """          # Handle stray None constants (Sliceobj seems to produce them).          if name == "NoneType":             return self.process_name_node(compiler.ast.Name("None"))          # Obtain the details of the literal itself.         # An alias to the type is generated for sequences.          if name in ("dict", "list", "tuple"):             ref = self.get_builtin_class(name)             self.set_special_literal(name, ref)             return self.process_literal_sequence_node(n, name, ref, LiteralSequenceRef)          # Constant values are independently recorded.          else:             value, typename, encoding = self.get_constant_value(n.value, n.literals)             ref = self.get_builtin_class(typename)             return self.get_constant_reference(ref, value, encoding)      # Special names.      def get_special(self, name):          "Return any stored value for the given special 'name'."          value = self.special.get(name)         if value:             ref, paths = value         else:             ref = None         return ref      def set_special(self, name, value):          """         Set a special 'name' that merely tracks the use of an implicit object         'value'.         """          if not self.special.has_key(name):             paths = set()             self.special[name] = value, paths         else:             _ref, paths = self.special[name]          paths.add(self.get_namespace_path())      def set_special_literal(self, name, ref):          """         Set a special name for the literal type 'name' having type 'ref'. Such         special names provide a way of referring to literal object types.         """          literal_name = "$L%s" % name         value = ResolvedNameRef(literal_name, ref)         self.set_special(literal_name, value)      # Exceptions.      def record_exception_handler(self):          "Record the current namespace as employing an exception handler."          self.exception_namespaces.add(self.get_namespace_path())      # Return values.      def record_return_value(self, expr):          "Record the given return 'expr'."          path = self.get_namespace_path()         l = init_item(self.return_values, path, list)         l.append(expr)         if not self.importer.all_return_values.has_key(path):             self.importer.all_return_values[path] = l  # vim: tabstop=4 expandtab shiftwidth=4