#!/usr/bin/env python  """ Translate programs.  Copyright (C) 2015, 2016, 2017 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 common import CommonModule, CommonOutput, \                    first, get_builtin_class, init_item, is_newer, \                    predefined_constants from encoders import encode_access_instruction, encode_access_instruction_arg, \                      encode_function_pointer, encode_literal_instantiator, \                      encode_instantiator_pointer, encode_path, encode_symbol, \                      encode_type_attribute, is_type_attribute from errors import InspectError, TranslateError from os.path import exists, join from os import makedirs from referencing import Reference, combine_types from results import Result from transresults import TrConstantValueRef, TrInstanceRef, \                          TrLiteralSequenceRef, TrResolvedNameRef, \                          AliasResult, AttrResult, Expression, InstantiationResult, \                          InvocationResult, LogicalOperationResult, \                          LogicalResult, NegationResult, PredefinedConstantRef, \                          ReturnRef from StringIO import StringIO import compiler import sys  class Translator(CommonOutput):      "A program translator."      def __init__(self, importer, deducer, optimiser, output):         self.importer = importer         self.deducer = deducer         self.optimiser = optimiser         self.output = output      def to_output(self, reset=False, debug=False, gc_sections=False):          "Write a program to the configured output directory."          # Make a directory for the final sources.          output = join(self.output, "src")          if not exists(output):             makedirs(output)          # Clean the output directory of irrelevant data.          self.check_output("debug=%r gc_sections=%r" % (debug, gc_sections))          for module in self.importer.modules.values():             output_filename = join(output, "%s.c" % module.name)              # Do not generate modules in the native package. They are provided             # by native functionality source files.              parts = module.name.split(".")              if parts[0] != "native" and \                (reset or is_newer(module.filename, output_filename)):                  tm = TranslatedModule(module.name, self.importer, self.deducer, self.optimiser)                 tm.translate(module.filename, output_filename)    def make_expression(expr):      "Make a new expression from the existing 'expr'."      if isinstance(expr, Result):         return expr     else:         return Expression(str(expr))    # The actual translation process itself.  class TranslatedModule(CommonModule):      "A module translator."      def __init__(self, name, importer, deducer, optimiser):         CommonModule.__init__(self, name, importer)         self.deducer = deducer         self.optimiser = optimiser          # Output stream.          self.out_toplevel = self.out = None         self.indent = 0         self.tabstop = "    "          # Recorded namespaces.          self.namespaces = []         self.in_conditional = False          # Exception raising adjustments.          self.in_try_finally = False         self.in_try_except = False          # Invocation adjustments.          self.in_argument_list = False          # Attribute access and accessor counting.          self.attr_accesses = {}         self.attr_accessors = {}          # Special variable usage.          self.temp_usage = {}          # Initialise some data used for attribute access generation.          self.init_substitutions()      def __repr__(self):         return "TranslatedModule(%r, %r)" % (self.name, self.importer)      def translate(self, filename, output_filename):          """         Parse the file having the given 'filename', writing the translation to         the given 'output_filename'.         """          self.parse_file(filename)          # Collect function namespaces for separate processing.          self.record_namespaces(self.astnode)          # Reset the lambda naming (in order to obtain the same names again) and         # translate the program.          self.reset_lambdas()          self.out_toplevel = self.out = open(output_filename, "w")         try:             self.start_output()              # Process namespaces, writing the translation.              for path, node in self.namespaces:                 self.process_namespace(path, node)              # Process the module namespace including class namespaces.              self.process_namespace([], self.astnode)          finally:             self.out.close()      def have_object(self):          "Return whether a namespace is a recorded object."          return self.importer.objects.get(self.get_namespace_path())      def get_builtin_class(self, name):          "Return a reference to the actual object providing 'name'."          return self.importer.get_object(get_builtin_class(name))      def is_method(self, path):          "Return whether 'path' is a method."          class_name, method_name = path.rsplit(".", 1)         return self.importer.classes.has_key(class_name) and class_name or None      def in_method(self):          "Return whether the current namespace provides a method."          return self.in_function and self.is_method(self.get_namespace_path())      # Namespace recording.      def record_namespaces(self, node):          "Process the program structure 'node', recording namespaces."          for n in node.getChildNodes():             self.record_namespaces_in_node(n)      def record_namespaces_in_node(self, node):          "Process the program structure 'node', recording namespaces."          # Function namespaces within modules, classes and other functions.         # Functions appearing within conditional statements are given arbitrary         # names.          if isinstance(node, compiler.ast.Function):             self.record_function_node(node, (self.in_conditional or self.in_function) and self.get_lambda_name() or node.name)          elif isinstance(node, compiler.ast.Lambda):             self.record_function_node(node, self.get_lambda_name())          # Classes are visited, but may be ignored if inside functions.          elif isinstance(node, compiler.ast.Class):             self.enter_namespace(node.name)             if self.have_object():                 self.record_namespaces(node)             self.exit_namespace()          # Conditional nodes are tracked so that function definitions may be         # handled. Since "for" loops are converted to "while" loops, they are         # included here.          elif isinstance(node, (compiler.ast.For, compiler.ast.If, compiler.ast.While)):             in_conditional = self.in_conditional             self.in_conditional = True             self.record_namespaces(node)             self.in_conditional = in_conditional          # All other nodes are processed depth-first.          else:             self.record_namespaces(node)      def record_function_node(self, n, name):          """         Record the given function, lambda, if expression or list comprehension         node 'n' with the given 'name'.         """          self.in_function = True         self.enter_namespace(name)          if self.have_object():              # Record the namespace path and the node itself.              self.namespaces.append((self.namespace_path[:], n))             self.record_namespaces_in_node(n.code)          self.exit_namespace()         self.in_function = False      # Constant referencing.      def get_literal_instance(self, n, name=None):          """         For node 'n', return a reference for the type of the given 'name', or if         'name' is not specified, deduce the type from the value.         """          # Handle stray None constants (Sliceobj seems to produce them).          if name is None and n.value is None:             return self.process_name_node(compiler.ast.Name("None"))          if name in ("dict", "list", "tuple"):             ref = self.get_builtin_class(name)             return self.process_literal_sequence_node(n, name, ref, TrLiteralSequenceRef)         else:             value, typename, encoding = self.get_constant_value(n.value, n.literals)             ref = self.get_builtin_class(typename)             value_type = ref.get_origin()              path = self.get_namespace_path()              # Obtain the local numbering of the constant and thus the             # locally-qualified name.              local_number = self.importer.all_constants[path][(value, value_type, encoding)]             constant_name = "$c%d" % local_number             objpath = self.get_object_path(constant_name)              # Obtain the unique identifier for the constant.              number = self.optimiser.constant_numbers[objpath]             return TrConstantValueRef(constant_name, ref.instance_of(), value, number)      # Namespace translation.      def process_namespace(self, path, node):          """         Process the namespace for the given 'path' defined by the given 'node'.         """          self.namespace_path = path          if isinstance(node, (compiler.ast.Function, compiler.ast.Lambda)):             self.in_function = True             self.process_function_body_node(node)         else:             self.in_function = False             self.function_target = 0             self.max_function_targets = 0             self.start_module()             self.process_structure(node)             self.end_module()      def process_structure(self, node):          "Process the given 'node' or result."          # Handle processing requests on results.          if isinstance(node, Result):             return node          # Handle processing requests on nodes.          else:             l = CommonModule.process_structure(self, node)              # Return indications of return statement usage.              if l and isinstance(l[-1], ReturnRef):                 return l[-1]             else:                 return None      def process_structure_node(self, n):          "Process the individual node 'n'."          # Plain statements emit their expressions.          if isinstance(n, compiler.ast.Discard):             expr = self.process_structure_node(n.expr)             self.statement(expr)          # Module import declarations.          elif isinstance(n, compiler.ast.From):             self.process_from_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)          # Classes are visited, but may be ignored if inside functions.          elif isinstance(n, compiler.ast.Class):             self.process_class_node(n)          # Functions within namespaces have any dynamic defaults initialised.          elif isinstance(n, compiler.ast.Function):             self.process_function_node(n)          # Lambdas are replaced with references to separately-generated         # functions.          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)          # Accesses.          elif isinstance(n, compiler.ast.Getattr):             return self.process_attribute_access(n)          # Names.          elif isinstance(n, compiler.ast.Name):             return self.process_name_node(n)          # Loops and conditionals.          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)          elif isinstance(n, compiler.ast.Not):             return self.process_not_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.writestmt("break;")          elif isinstance(n, compiler.ast.Continue):             self.writestmt("continue;")          elif isinstance(n, compiler.ast.Raise):             self.process_raise_node(n)          elif isinstance(n, compiler.ast.Return):             return self.process_return_node(n)          # Print statements.          elif isinstance(n, (compiler.ast.Print, compiler.ast.Printnl)):             self.statement(self.process_print_node(n))          # Invocations.          elif isinstance(n, compiler.ast.CallFunc):             return self.process_invocation_node(n)          elif isinstance(n, compiler.ast.Keyword):             return self.process_structure_node(n.expr)          # 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:             return self.process_structure(n)      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):             name_ref = self.process_name_node(n, self.process_structure_node(expr))             self.statement(name_ref)              # Employ guards after assignments if required.              if expr and name_ref.is_name():                 self.generate_guard(name_ref.name)          elif isinstance(n, compiler.ast.AssAttr):             in_assignment = self.in_assignment             self.in_assignment = self.process_structure_node(expr)             self.statement(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.statement(self.process_slice_node(n, expr))          elif isinstance(n, compiler.ast.Subscript):             self.statement(self.process_subscript_node(n, expr))      def process_attribute_access(self, n):          "Process the given attribute access node 'n'."          # Obtain any completed chain and return the reference to it.          attr_expr = self.process_attribute_chain(n)         if self.have_access_expression(n):             return attr_expr          # Where the start of the chain of attributes has been reached, process         # the complete access.          name_ref = attr_expr and attr_expr.is_name() and attr_expr         name = name_ref and self.get_name_for_tracking(name_ref.name, name_ref) or None          location = self.get_access_location(name, self.attrs)         refs = self.get_referenced_attributes(location)          # Generate access instructions.          subs = {             "<expr>" : attr_expr,             "<name>" : attr_expr,             "<assexpr>" : self.in_assignment,             }          subs.update(self.temp_subs)         subs.update(self.op_subs)          output = []         substituted = set()          # The context set or retrieved will be that used by any enclosing         # invocation.          context_index = self.function_target - 1         context_identity = None         final_identity = None          # Obtain encoded versions of each instruction, accumulating temporary         # variables.          for instruction in self.deducer.access_instructions[location]:              # Intercept a special instruction identifying the context.              if instruction[0] == "<context_identity>":                 context_identity, _substituted = encode_access_instruction_arg(instruction[1], subs, instruction[0], context_index)                 continue              # Intercept a special instruction identifying the target. The value             # is not encoded since it is used internally.              if instruction[0] == "<final_identity>":                 final_identity = instruction[1]                 continue              # Collect the encoded instruction, noting any temporary variables             # required by it.              encoded, _substituted = encode_access_instruction(instruction, subs, context_index)             output.append(encoded)             substituted.update(_substituted)          # Record temporary name usage.          for sub in substituted:             if self.temp_subs.has_key(sub):                 self.record_temp(self.temp_subs[sub])          # Get full final identity details.          if final_identity and not refs:             ref = self.importer.identify(final_identity)             refs = [ref]          del self.attrs[0]         return AttrResult(output, refs, location, context_identity)      def init_substitutions(self):          """         Initialise substitutions, defining temporary variable mappings, some of         which are also used as substitutions, together with operation mappings         used as substitutions in instructions defined by the optimiser.         """          self.temp_subs = {              # Substitutions used by instructions.              "<private_context>" : "__tmp_private_context",             "<accessor>" : "__tmp_value",             "<target_accessor>" : "__tmp_target_value",              # Mappings to be replaced by those given below.              "<context>" : "__tmp_contexts",             "<test_context_revert>" : "__tmp_contexts",             "<test_context_static>" : "__tmp_contexts",             "<set_context>" : "__tmp_contexts",             "<set_private_context>" : "__tmp_private_context",             "<set_accessor>" : "__tmp_value",             "<set_target_accessor>" : "__tmp_target_value",             }          self.op_subs = {             "<context>" : "__get_context",             "<test_context_revert>" : "__test_context_revert",             "<test_context_static>" : "__test_context_static",             "<set_context>" : "__set_context",             "<set_private_context>" : "__set_private_context",             "<set_accessor>" : "__set_accessor",             "<set_target_accessor>" : "__set_target_accessor",             }      def get_referenced_attributes(self, location):          """         Convert 'location' to the form used by the deducer and retrieve any         identified attributes.         """          # Determine whether any deduced references refer to the accessed         # attribute.          path, accessor_name, attrnames, access_number = location         attrnames = attrnames and attrnames.split(".")         remaining = attrnames and len(attrnames) > 1          access_location = self.deducer.const_accesses.get(location)          if remaining and not access_location:             return []          refs = []         l = self.deducer.referenced_attrs.get(access_location or location)         if l:             for attrtype, objpath, attr in l:                 refs.append(attr)         return refs      def get_referenced_attribute_invocations(self, location):          """         Convert 'location' to the form used by the deducer and retrieve any         identified attribute invocation details.         """          access_location = self.deducer.const_accesses.get(location)         return self.deducer.reference_invocations_unsuitable.get(access_location or location)      def get_accessor_kinds(self, location):          "Return the accessor kinds for 'location'."          return self.deducer.accessor_kinds.get(location)      def get_access_location(self, name, attrnames=None):          """         Using the current namespace, the given 'name', and the 'attrnames'         employed in an access, return the access location.         """          path = self.get_path_for_access()          # Get the location used by the deducer and optimiser and find any         # recorded access.          attrnames = attrnames and ".".join(self.attrs)         access_number = self.get_access_number(path, name, attrnames)         self.update_access_number(path, name, attrnames)         return (path, name, attrnames, access_number)      def get_access_number(self, path, name, attrnames):         access = name, attrnames         if self.attr_accesses.has_key(path) and self.attr_accesses[path].has_key(access):             return self.attr_accesses[path][access]         else:             return 0      def update_access_number(self, path, name, attrnames):         access = name, attrnames         if name:             init_item(self.attr_accesses, path, dict)             init_item(self.attr_accesses[path], access, lambda: 0)             self.attr_accesses[path][access] += 1      def get_accessor_location(self, name):          """         Using the current namespace and the given 'name', return the accessor         location.         """          path = self.get_path_for_access()          # Get the location used by the deducer and optimiser and find any         # recorded accessor.          access_number = self.get_accessor_number(path, name)         self.update_accessor_number(path, name)         return (path, name, None, access_number)      def get_accessor_number(self, path, name):         if self.attr_accessors.has_key(path) and self.attr_accessors[path].has_key(name):             return self.attr_accessors[path][name]         else:             return 0      def update_accessor_number(self, path, name):         if name:             init_item(self.attr_accessors, path, dict)             init_item(self.attr_accessors[path], name, lambda: 0)             self.attr_accessors[path][name] += 1      def process_class_node(self, n):          "Process the given class node 'n'."          class_name = self.get_object_path(n.name)          # Where a class is set conditionally or where the name may refer to         # different values, assign the name.          ref = self.importer.identify(class_name)          if not ref.static():             self.process_assignment_for_object(n.name,                 make_expression("__ATTRVALUE(&%s)" % encode_path(class_name)))          self.enter_namespace(n.name)          if self.have_object():             self.write_comment("Class: %s" % class_name)              self.initialise_inherited_members(class_name)              self.process_structure(n)             self.write_comment("End class: %s" % class_name)          self.exit_namespace()      def initialise_inherited_members(self, class_name):          "Initialise members of 'class_name' inherited from its ancestors."          for name, path in self.importer.all_class_attrs[class_name].items():             target = "%s.%s" % (class_name, name)              # Ignore attributes with definitions.              ref = self.importer.identify(target)             if ref:                 continue              # Ignore special type attributes.              if is_type_attribute(name):                 continue              # Reference inherited attributes.              ref = self.importer.identify(path)             if ref and not ref.static():                 parent, attrname = path.rsplit(".", 1)                  self.writestmt("__store_via_object(&%s, %s, __load_via_object(&%s, %s));" % (                     encode_path(class_name), name,                     encode_path(parent), attrname                     ))      def process_from_node(self, n):          "Process the given node 'n', importing from another module."          path = self.get_namespace_path()          # 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)              # Obtain the path of the assigned name.              objpath = self.get_object_path(alias or name)              # Obtain the identity of the name.              ref = self.importer.identify(objpath)              # Where the name is not static, assign the value.              if ref and not ref.static() and ref.get_name():                 self.writestmt("%s;" %                      TrResolvedNameRef(alias or name, Reference("<var>", None, objpath),                                       expr=TrResolvedNameRef(name, ref)))      def process_function_body_node(self, n):          """         Process the given function, lambda, if expression or list comprehension         node 'n', generating the body.         """          function_name = self.get_namespace_path()         self.start_function(function_name)          # Process the function body.          in_conditional = self.in_conditional         self.in_conditional = False         self.function_target = 0         self.max_function_targets = 0          # Volatile locals for exception handling.          self.volatile_locals = set()          # Process any guards defined for the parameters.          for name in self.importer.function_parameters.get(function_name):             self.generate_guard(name)          # Produce the body and any additional return statement.          expr = self.process_structure_node(n.code) or \                self.in_method() and \                    function_name.rsplit(".", 1)[-1] == "__init__" and \                    TrResolvedNameRef("self", self.importer.function_locals[function_name]["self"]) or \                PredefinedConstantRef("None")          if not isinstance(expr, ReturnRef):             self.writestmt("return %s;" % expr)          self.in_conditional = in_conditional          self.end_function(function_name)      def generate_guard(self, name):          """         Get the accessor details for 'name', found in the current namespace, and         generate any guards defined for it.         """          # Obtain the location, keeping track of assignment versions.          location = self.get_accessor_location(name)         test = self.deducer.accessor_guard_tests.get(location)          # Generate any guard from the deduced information.          if test:             guard, guard_type = test              if guard == "specific":                 ref = first(self.deducer.accessor_all_types[location])                 argstr = "&%s" % encode_path(ref.get_origin())             elif guard == "common":                 ref = first(self.deducer.accessor_all_general_types[location])                 argstr = encode_path(encode_type_attribute(ref.get_origin()))             else:                 return              # Write a test that raises a TypeError upon failure.              self.writestmt("if (!__test_%s_%s(__VALUE(%s), %s)) __raise_type_error();" % (                 guard, guard_type, encode_path(name), argstr))      def process_function_node(self, n):          """         Process the given function, lambda, if expression or list comprehension         node 'n', generating any initialisation statements.         """          # Where a function is declared conditionally, use a separate name for         # the definition, and assign the definition to the stated name.          original_name = n.name          if self.in_conditional or self.in_function:             name = self.get_lambda_name()         else:             name = n.name          objpath = self.get_object_path(name)          # Obtain details of the defaults.          defaults = self.process_function_defaults(n, name, objpath)         if defaults:             for default in defaults:                 self.writeline("%s;" % default)          # Where a function is set conditionally or where the name may refer to         # different values, assign the name.          ref = self.importer.identify(objpath)          if self.in_conditional or self.in_function:             self.process_assignment_for_object(original_name, compiler.ast.Name(name))         elif not ref.static():             context = self.is_method(objpath)              self.process_assignment_for_object(original_name,                 make_expression("__ATTRVALUE(&%s)" % encode_path(objpath)))      def process_function_defaults(self, n, name, objpath, instance_name=None):          """         Process the given function or lambda node 'n', initialising defaults         that are dynamically set. The given 'name' indicates the name of the         function. The given 'objpath' indicates the origin of the function.         The given 'instance_name' indicates the name of any separate instance         of the function created to hold the defaults.          Return a list of operations setting defaults on a function instance.         """          function_name = self.get_object_path(name)         function_defaults = self.importer.function_defaults.get(function_name)         if not function_defaults:             return None          # Determine whether any unidentified defaults are involved.          for argname, default in function_defaults:             if not default.static():                 break         else:             return None          # Handle bound methods.          if not instance_name:             instance_name = "&%s" % encode_path(objpath)         else:             instance_name = "__VALUE(%s)" % instance_name          # Where defaults are involved but cannot be identified, obtain a new         # instance of the lambda and populate the defaults.          defaults = []          # Join the original defaults with the inspected defaults.          original_defaults = [(argname, default) for (argname, default) in compiler.ast.get_defaults(n) if default]          for i, (original, inspected) in enumerate(map(None, original_defaults, function_defaults)):              # Obtain any reference for the default.              if original:                 argname, default = original                 name_ref = self.process_structure_node(default)             elif inspected:                 argname, default = inspected                 name_ref = TrResolvedNameRef(argname, default)             else:                 continue              # Generate default initialisers except when constants are employed.             # Constants should be used when populating the function structures.              if name_ref and not isinstance(name_ref, TrConstantValueRef):                 defaults.append("__SETDEFAULT(%s, %s, %s)" % (instance_name, i, name_ref))          return defaults      def process_if_node(self, n):          """         Process the given "if" node 'n'.         """          first = True         for test, body in n.tests:             test_ref = self.process_structure_node(test)             self.start_if(first, test_ref)              in_conditional = self.in_conditional             self.in_conditional = True             self.process_structure_node(body)             self.in_conditional = in_conditional              self.end_if()             first = False          if n.else_:             self.start_else()             self.process_structure_node(n.else_)             self.end_else()          print >>self.out      def process_invocation_node(self, n):          "Process the given invocation node 'n'."          # Any invocations in the expression will store target details in a         # different location.          self.next_target()          in_argument_list = self.in_argument_list         self.in_argument_list = False          # Process the expression.          expr = self.process_structure_node(n.node)          # Reference the current target again.          self.in_argument_list = in_argument_list         self.function_target -= 1          # Obtain details of the invocation expression.          objpath = expr.get_origin()         location = expr.access_location()         refs = expr.references()          # Identified target details.          target = None         target_structure = None          # Specific function target information.          function = None          # Instantiation involvement.          instantiation = False         literal_instantiation = False          # Invocation requirements.          context_required = True         have_access_context = isinstance(expr, AttrResult)         context_identity = have_access_context and expr.context()         parameters = None         num_parameters = None         num_defaults = None          # Obtain details of the callable and of its parameters.          # Literals may be instantiated specially.          if expr.is_name() and expr.name.startswith("$L") and objpath:             instantiation = literal_instantiation = objpath             target = encode_literal_instantiator(objpath)             context_required = False          # Identified targets employ function pointers directly.          elif objpath:             parameters = self.importer.function_parameters.get(objpath)             function_defaults = self.importer.function_defaults.get(objpath)             num_parameters = parameters and len(parameters) or 0             num_defaults = function_defaults and len(function_defaults) or 0              # Class invocation involves instantiators.              if expr.has_kind("<class>"):                 instantiation = objpath                 target = encode_instantiator_pointer(objpath)                 init_ref = self.importer.all_class_attrs[objpath]["__init__"]                 target_structure = "&%s" % encode_path(init_ref)                 context_required = False              # Only plain functions and bound methods employ function pointers.              elif expr.has_kind("<function>"):                 function = objpath                  # Test for functions and methods.                  context_required = self.is_method(objpath)                  accessor_kinds = location and self.get_accessor_kinds(location)                  instance_accessor = accessor_kinds and \                                     len(accessor_kinds) == 1 and \                                     first(accessor_kinds) == "<instance>"                  # Only identify certain bound methods or functions.                  if not context_required or instance_accessor:                     target = encode_function_pointer(objpath)                  # Access bound method defaults even if it is not clear whether                 # the accessor is appropriate.                  target_structure = "&%s" % encode_path(objpath)          # Other targets are retrieved at run-time.          else:             if location:                 path, name, attrnames, access_number = location                 attrname = attrnames and attrnames.rsplit(".", 1)[-1]                  # Determine any common aspects of any attribute.                  if attrname:                     all_params = set()                     all_defaults = set()                     min_params = set()                     max_params = set()                     refs = set()                      # Obtain parameters and defaults for each possible target.                      for ref in self.get_attributes_for_attrname(attrname):                         origin = ref.get_origin()                         params = self.importer.function_parameters.get(origin)                          defaults = self.importer.function_defaults.get(origin)                         if defaults is not None:                             all_defaults.add(tuple(defaults))                          if params is not None:                             all_params.add(tuple(params))                             min_params.add(len(params) - (defaults and len(defaults) or 0))                             max_params.add(len(params))                             refs.add(ref)                         else:                             refs = set()                             break                      # Where the parameters and defaults are always the same,                     # permit populating them in advance.                      if refs:                         if self.uses_keyword_arguments(n):                             if len(all_params) == 1 and (not all_defaults or len(all_defaults) == 1):                                 parameters = first(all_params)                                 function_defaults = all_defaults and first(all_defaults) or []                                 num_parameters = parameters and len(parameters) or 0                                 num_defaults = function_defaults and len(function_defaults) or 0                         else:                             if len(min_params) == 1 and len(max_params) == 1:                                 num_parameters = first(max_params)                                 num_defaults = first(max_params) - first(min_params)              # Some information about the target may be available and be used to             # provide warnings about argument compatibility.              if self.importer.give_warning("args"):                 unsuitable = self.get_referenced_attribute_invocations(location)                  if unsuitable:                     for ref in unsuitable:                         _objpath = ref.get_origin()                         print >>sys.stderr, \                             "In %s, at line %d, inappropriate number of " \                             "arguments given. Need %d arguments to call %s." % (                             self.get_namespace_path(), n.lineno,                             len(self.importer.function_parameters[_objpath]),                             _objpath)          # Determine any readily-accessible target identity.          target_named = expr.is_name() and str(expr) or None         target_stored = "__tmp_targets[%d]" % self.function_target          target_identity = target or target_named         target_var = target_identity or target_stored         context_var = target_named or target_stored          if not target_identity:             self.record_temp("__tmp_targets")          if context_identity:             if context_identity.startswith("__tmp_contexts"):                 self.record_temp("__tmp_contexts")          # Arguments are presented in a temporary frame array with any context         # always being the first argument. Where it would be unused, it may be         # set to null.          known_parameters = num_parameters is not None          if context_required:             if have_access_context:                 args = [context_identity]             else:                 args = ["__CONTEXT_AS_VALUE(%s)" % context_var]         else:             args = ["__NULL"]          # Complete the array with null values, permitting tests for a complete         # set of arguments.          args += [None] * (num_parameters is None and len(n.args) or num_parameters is not None and num_parameters or 0)         kwcodes = []         kwargs = []          # Any invocations in the arguments will store target details in a         # different location.          function_target = self.function_target          if not target_identity:             self.next_target()          in_argument_list = self.in_argument_list         self.in_argument_list = True          for i, arg in enumerate(n.args):             argexpr = self.process_structure_node(arg)              # Store a keyword argument, either in the argument list or             # in a separate keyword argument list for subsequent lookup.              if isinstance(arg, compiler.ast.Keyword):                  # With knowledge of the target, store the keyword                 # argument directly.                  if parameters:                     try:                         argnum = parameters.index(arg.name)                     except ValueError:                         raise TranslateError("Argument %s is not recognised." % arg.name,                                              self.get_namespace_path(), n)                     args[argnum+1] = str(argexpr)                  # Otherwise, store the details in a separate collection.                  else:                     kwargs.append(str(argexpr))                     kwcodes.append("{%s, %s}" % (                         encode_ppos(arg.name), encode_pcode(arg.name)))              # Store non-keyword arguments in the argument list, rejecting             # superfluous arguments.              else:                 try:                     args[i+1] = str(argexpr)                 except IndexError:                     raise TranslateError("Too many arguments specified.",                                          self.get_namespace_path(), n)          # Reference the current target again.          self.in_argument_list = in_argument_list          if not self.in_argument_list:             self.function_target = function_target          # Defaults are added to the frame where arguments are missing.          if parameters and function_defaults:              # Visit each default and set any missing arguments. Where keyword             # arguments have been used, the defaults must be inspected and, if             # necessary, inserted into gaps in the argument list.              for i, (argname, default) in enumerate(function_defaults):                 argnum = parameters.index(argname)                 if not args[argnum+1]:                     args[argnum+1] = "__GETDEFAULT(%s, %d)" % (target_structure, i)          elif known_parameters:              # No specific parameter details are provided, but no keyword             # arguments are used. Thus, defaults can be supplied using position             # information only.              i = len(n.args)             pos = i - (num_parameters - num_defaults)             while i < num_parameters:                 args[i+1] = "__GETDEFAULT(%s.value, %d)" % (target_var, pos)                 i += 1                 pos += 1          # Test for missing arguments.          if None in args:             raise TranslateError("Not all arguments supplied.",                                  self.get_namespace_path(), n)          # Encode the arguments.          # Where literal instantiation is occurring, add an argument indicating         # the number of values. The context is excluded.          if literal_instantiation:             argstr = "__ARGS(%s), %d" % (", ".join(args[1:]), len(args) - 1)         else:             argstr = ", ".join(args)          kwargstr = kwargs and ("__ARGS(%s)" % ", ".join(kwargs)) or "0"         kwcodestr = kwcodes and ("__KWARGS(%s)" % ", ".join(kwcodes)) or "0"          # First, the invocation expression is presented.          stages = []          # Without a known specific callable, the expression provides the target.          if not target or context_required:              # The context is set in the expression.              if target and not target_named:                  # Test whether the expression provides anything.                  if expr:                     stages.append(str(expr))              elif not target_identity:                 stages.append("%s = %s" % (target_var, expr))          # Any specific callable is then obtained for invocation.          if target:             stages.append(target)          # Methods accessed via unidentified accessors are obtained for         # invocation.          elif function:             if context_required:                 if have_access_context:                     stages.append("__get_function(%s, %s)" % (                         context_identity, target_var))                 else:                     stages.append("__get_function(__CONTEXT_AS_VALUE(%s), %s)" % (                         context_var, target_var))             else:                 stages.append("__load_via_object(__VALUE(%s), __fn__).fn" % target_var)          # With known parameters, the target can be tested.          elif known_parameters:             context_arg = context_required and args[0] or "__NULL"             if self.always_callable(refs):                 stages.append("__get_function(%s, %s)" % (context_arg, target_var))             else:                 stages.append("__check_and_get_function(%s, %s)" % (context_arg, target_var))          # With a known target, the function is obtained directly and called.         # By putting the invocation at the end of the final element in the         # instruction sequence (the stages), the result becomes the result of         # the sequence. Moreover, the parameters become part of the sequence         # and thereby participate in a guaranteed evaluation order.          if target or function or known_parameters:             stages[-1] += "(%s)" % argstr             if instantiation:                 return InstantiationResult(instantiation, stages)             else:                 return InvocationResult(stages)          # With unknown targets, the generic invocation function is applied to         # the callable and argument collections.          else:             stages.append("__invoke(\n%s,\n%d, %d, %s, %s,\n%d, %s\n)" % (                 target_var,                 self.always_callable(refs) and 1 or 0,                 len(kwargs), kwcodestr, kwargstr,                 len(args), "__ARGS(%s)" % argstr))             return InvocationResult(stages)      def next_target(self):          "Allocate the next function target storage."          self.function_target += 1         self.max_function_targets = max(self.function_target, self.max_function_targets)      def always_callable(self, refs):          "Determine whether all 'refs' are callable."          if not refs:             return False          for ref in refs:             if not ref.has_kind("<function>") and not self.importer.get_attributes(ref, "__fn__"):                 return False          return True      def need_default_arguments(self, objpath, nargs):          """         Return whether any default arguments are needed when invoking the object         given by 'objpath'.         """          parameters = self.importer.function_parameters.get(objpath)         return nargs < len(parameters)      def uses_keyword_arguments(self, n):          "Return whether invocation node 'n' uses keyword arguments."          for arg in enumerate(n.args):             if isinstance(arg, compiler.ast.Keyword):                 return True          return False      def get_attributes_for_attrname(self, attrname):          "Return a set of all attributes exposed by 'attrname'."          usage = [(attrname, True, False)]         class_types = self.deducer.get_class_types_for_usage(usage)         instance_types = self.deducer.get_instance_types_for_usage(usage)         module_types = self.deducer.get_module_types_for_usage(usage)         attrs = set()          for ref in combine_types(class_types, instance_types, module_types):             attrs.update(self.importer.get_attributes(ref, attrname))          return attrs      def process_lambda_node(self, n):          "Process the given lambda node 'n'."          name = self.get_lambda_name()         function_name = self.get_object_path(name)          defaults = self.process_function_defaults(n, name, function_name, "__tmp_value")          # Without defaults, produce an attribute referring to the function.          if not defaults:             return make_expression("__ATTRVALUE(&%s)" % encode_path(function_name))          # With defaults, copy the function structure and set the defaults on the         # copy.          else:             self.record_temp("__tmp_value")             return make_expression("(__tmp_value = __ATTRVALUE(__COPY(&%s, sizeof(%s))), %s, __tmp_value)" % (                 encode_path(function_name),                 encode_symbol("obj", function_name),                 ", ".join(defaults)))      def process_logical_node(self, n):          "Process the given operator node 'n'."          self.record_temp("__tmp_result")          conjunction = isinstance(n, compiler.ast.And)         results = []          for node in n.nodes:             results.append(self.process_structure_node(node))          return LogicalOperationResult(results, conjunction)      def process_name_node(self, n, expr=None):          "Process the given name node 'n' with the optional assignment 'expr'."          # Determine whether the name refers to a static external entity.          if n.name in predefined_constants:             return PredefinedConstantRef(n.name, expr)          # Convert literal references, operator function names, and print         # function names to references.          elif n.name.startswith("$L") or n.name.startswith("$op") or \              n.name.startswith("$print"):              ref, paths = self.importer.get_module(self.name).special[n.name]             return TrResolvedNameRef(n.name, ref)          # Get the appropriate name for the name reference, using the same method         # as in the inspector.          path = self.get_namespace_path()         objpath = self.get_object_path(n.name)          # Determine any assigned globals.          globals = self.importer.get_module(self.name).scope_globals.get(path)          # Explicitly declared globals.          if globals and n.name in globals:             objpath = self.get_global_path(n.name)             is_global = True          # Implicitly referenced globals in functions.          elif self.in_function:             is_global = n.name not in self.importer.function_locals[path]          # Implicitly referenced globals elsewhere.          else:             namespace = self.importer.identify(path)             is_global = not self.importer.get_attributes(namespace, n.name)          # Get the static identity of the name.          ref = self.importer.identify(objpath)         if ref and not ref.get_name():             ref = ref.alias(objpath)          # Obtain any resolved names for non-assignment names.          if not expr and not ref and self.in_function:             locals = self.importer.function_locals.get(path)             ref = locals and locals.get(n.name)          # Determine whether the name refers to a parameter. The generation of         # parameter references is different from other names.          parameters = self.importer.function_parameters.get(path)         parameter = n.name == "self" and self.in_method() or \                     parameters and n.name in parameters          # Find any invocation or alias details.          name = self.get_name_for_tracking(n.name, is_global=is_global)         location = not expr and self.get_access_location(name) or None          # Mark any local assignments as volatile in exception blocks.          if expr and self.in_function and not is_global and self.in_try_except:             self.make_volatile(n.name)          # Qualified names are used for resolved static references or for         # static namespace members. The reference should be configured to return         # such names.          name_ref = TrResolvedNameRef(n.name, ref, expr=expr, is_global=is_global,                                      location=location)         return not expr and self.get_aliases(name_ref) or name_ref      def get_aliases(self, name_ref):          "Return alias references for the given 'name_ref'."          location = name_ref.access_location()          refs = self.deducer.referenced_objects.get(location)         refs = refs or self.deducer.accessor_all_types.get(location)         return AliasResult(name_ref, refs or set(), location)      def make_volatile(self, name):          "Record 'name' as volatile in the current namespace."          self.volatile_locals.add(name)      def process_not_node(self, n):          "Process the given operator node 'n'."          return self.make_negation(self.process_structure_node(n.expr))      def process_raise_node(self, n):          "Process the given raise node 'n'."          # NOTE: Determine which raise statement variants should be permitted.          if n.expr1:              # Names with accompanying arguments are treated like invocations.              if n.expr2:                 call = compiler.ast.CallFunc(n.expr1, [n.expr2])                 exc = self.process_structure_node(call)                 self.writestmt("__Raise(%s);" % exc)              # Raise instances, testing the kind at run-time if necessary and             # instantiating any non-instance.              else:                 exc = self.process_structure_node(n.expr1)                  if isinstance(exc, TrInstanceRef):                     self.writestmt("__Raise(%s);" % exc)                 else:                     self.writestmt("__Raise(__ensure_instance(%s));" % exc)         else:             self.writestmt("__Throw(__tmp_exc);")      def process_return_node(self, n):          "Process the given return node 'n'."          expr = self.process_structure_node(n.value) or PredefinedConstantRef("None")         if self.in_try_finally or self.in_try_except:             self.writestmt("__Return(%s);" % expr)         else:             self.writestmt("return %s;" % expr)          return ReturnRef()      def process_try_node(self, n):          """         Process the given "try...except" node 'n'.         """          in_try_except = self.in_try_except         self.in_try_except = True          # Use macros to implement exception handling.          self.writestmt("__Try")         self.writeline("{")         self.indent += 1         self.process_structure_node(n.body)          # Put the else statement in another try block that handles any raised         # exceptions and converts them to exceptions that will not be handled by         # the main handling block.          if n.else_:             self.writestmt("__Try")             self.writeline("{")             self.indent += 1             self.process_structure_node(n.else_)             self.indent -= 1             self.writeline("}")             self.writeline("__Catch (__tmp_exc)")             self.writeline("{")             self.indent += 1             self.writeline("if (__tmp_exc.raising) __RaiseElse(__tmp_exc.arg);")             self.writeline("else if (__tmp_exc.completing) __Throw(__tmp_exc);")             self.indent -= 1             self.writeline("}")          # Complete the try block and enter the finally block, if appropriate.          if self.in_try_finally:             self.writestmt("__Complete;")          self.indent -= 1         self.writeline("}")          self.in_try_except = in_try_except          # Handlers are tests within a common handler block.          self.writeline("__Catch (__tmp_exc)")         self.writeline("{")         self.indent += 1          # Introduce an if statement to handle the completion of a try block.          self.process_try_completion()          # Handle exceptions in else blocks converted to __RaiseElse, converting         # them back to normal exceptions.          if n.else_:             self.writeline("else if (__tmp_exc.raising_else) __Raise(__tmp_exc.arg);")          # Exception handling.          for name, var, handler in n.handlers:              # Test for specific exceptions.              if name is not None:                 name_ref = self.process_structure_node(name)                 self.writeline("else if (__ISINSTANCE(__tmp_exc.arg, %s))" % name_ref)             else:                 self.writeline("else if (1)")              self.writeline("{")             self.indent += 1              # Establish the local for the handler.              if var is not None:                 self.writestmt("%s;" % self.process_name_node(var, make_expression("__tmp_exc.arg")))              if handler is not None:                 self.process_structure_node(handler)              self.indent -= 1             self.writeline("}")          # Re-raise unhandled exceptions.          self.writeline("else __Throw(__tmp_exc);")          # End the handler block.          self.indent -= 1         self.writeline("}")         print >>self.out      def process_try_finally_node(self, n):          """         Process the given "try...finally" node 'n'.         """          in_try_finally = self.in_try_finally         self.in_try_finally = True          # Use macros to implement exception handling.          self.writestmt("__Try")         self.writeline("{")         self.indent += 1         self.process_structure_node(n.body)         self.indent -= 1         self.writeline("}")          self.in_try_finally = in_try_finally          # Finally clauses handle special exceptions.          self.writeline("__Catch (__tmp_exc)")         self.writeline("{")         self.indent += 1         self.process_structure_node(n.final)          # Introduce an if statement to handle the completion of a try block.          self.process_try_completion()         self.writeline("else __Throw(__tmp_exc);")          self.indent -= 1         self.writeline("}")         print >>self.out      def process_try_completion(self):          "Generate a test for the completion of a try block."          self.writestmt("if (__tmp_exc.completing)")         self.writeline("{")         self.indent += 1          # Do not return anything at the module level.          if self.get_namespace_path() != self.name:              # Only use the normal return statement if no surrounding try blocks             # apply.              if not self.in_try_finally and not self.in_try_except:                 self.writeline("if (!__ISNULL(__tmp_exc.arg)) return __tmp_exc.arg;")             else:                 self.writeline("if (!__ISNULL(__tmp_exc.arg)) __Throw(__tmp_exc);")          self.indent -= 1         self.writeline("}")      def process_while_node(self, n):          "Process the given while node 'n'."          self.writeline("while (1)")         self.writeline("{")         self.indent += 1         test = self.process_structure_node(n.test)          # Emit the loop termination condition unless "while <true value>" is         # indicated.          if not (isinstance(test, PredefinedConstantRef) and test.value):              # Emit a negated test of the continuation condition.              self.start_if(True, self.make_negation(test))             if n.else_:                 self.process_structure_node(n.else_)             self.writestmt("break;")             self.end_if()          in_conditional = self.in_conditional         self.in_conditional = True         self.process_structure_node(n.body)         self.in_conditional = in_conditional          self.indent -= 1         self.writeline("}")         print >>self.out      # Special variable usage.      def get_temp_path(self):          """         Return the appropriate namespace path for temporary names in the current         namespace.         """          if self.in_function:             return self.get_namespace_path()         else:             return self.name      def record_temp(self, name):          """         Record the use of the temporary 'name' in the current namespace. At the         class or module level, the temporary name is associated with the module,         since the variable will then be allocated in the module's own main         program.         """          path = self.get_temp_path()          init_item(self.temp_usage, path, list)         self.temp_usage[path].append(name)      def remove_temps(self, names):          """         Remove 'names' from temporary storage allocations, each instance         removing each request for storage.         """          path = self.get_temp_path()          for name in names:             if self.uses_temp(path, name):                 self.temp_usage[path].remove(name)      def uses_temp(self, path, name):          """         Return whether the given namespace 'path' employs a temporary variable         with the given 'name'. Note that 'path' should only be a module or a         function or method, not a class.         """          return self.temp_usage.has_key(path) and name in self.temp_usage[path]      def make_negation(self, expr):          "Return a negated form of 'expr'."          result = NegationResult(expr)          # Negation discards the temporary results of its operand.          temps = expr.discards_temporary()         if temps:             self.remove_temps(temps)          return result      # Output generation.      def start_output(self):          "Write the declarations at the top of each source file."          print >>self.out, """\ #include "types.h" #include "exceptions.h" #include "ops.h" #include "progconsts.h" #include "progops.h" #include "progtypes.h" #include "main.h" """      def start_unit(self):          "Record output within a generated function for later use."          self.out = StringIO()      def end_unit(self):          "Restore the output stream."          out = self.out         self.out = self.out_toplevel         return out      def flush_unit(self, name, out):          "Add declarations and generated code."          self.write_temporaries(name)         print >>self.out         out.seek(0)         self.out.write(out.read())      def start_module(self):          "Write the start of each module's main function."          print >>self.out, "void __main_%s()" % encode_path(self.name)         print >>self.out, "{"         self.indent += 1          # Define temporary variables, excluded from the module structure itself.          tempnames = []          for n in self.importer.all_module_attrs[self.name]:             if n.startswith("$t"):                 tempnames.append(encode_path(n))          if tempnames:             tempnames.sort()             self.writeline("__attr %s;" % ", ".join(tempnames))          self.start_unit()      def end_module(self):          "End each module by closing its main function."          out = self.end_unit()         self.flush_unit(self.name, out)          self.indent -= 1         print >>self.out, "}"      def start_function(self, name):          "Start the function having the given 'name'."          self.indent += 1          self.start_unit()      def end_function(self, name):          "End the function having the given 'name'."          out = self.end_unit()          # Write the signature at the top indentation level.          self.indent -= 1         self.write_parameters(name)         print >>self.out, "{"          # Obtain local names from parameters.          parameters = self.importer.function_parameters[name]         locals = self.importer.function_locals[name].keys()         names = []         volatile_names = []          for n in locals:              # Filter out special names and parameters. Note that self is a local             # regardless of whether it originally appeared in the parameters or             # not.              if n.startswith("$l") or n in parameters or n == "self":                 continue             if n in self.volatile_locals:                 volatile_names.append(encode_path(n))             else:                 names.append(encode_path(n))          # Emit required local names at the function indentation level.          self.indent += 1          if names:             names.sort()             self.writeline("__attr %s;" % ", ".join(names))          if volatile_names:             volatile_names.sort()             self.writeline("volatile __attr %s;" % ", ".join(volatile_names))          self.flush_unit(name, out)          self.indent -= 1         print >>self.out, "}"         print >>self.out      def write_parameters(self, name):          """         For the function having the given 'name', write definitions of         parameters found in the arguments array.         """          # Generate any self reference.          l = []          if self.is_method(name):             l.append("__attr self")         else:             l.append("__attr __self")          # Generate aliases for the parameters.          for parameter in self.importer.function_parameters[name]:             l.append("%s__attr %s" % (                 parameter in self.volatile_locals and "volatile " or "",                 encode_path(parameter)))          self.writeline("__attr %s(%s)" % (             encode_function_pointer(name), ", ".join(l)))      def write_temporaries(self, name):          "Write temporary storage employed by 'name'."          # Provide space for the given number of targets.          targets = self.max_function_targets          if self.uses_temp(name, "__tmp_targets"):             self.writeline("__attr __tmp_targets[%d];" % targets)         if self.uses_temp(name, "__tmp_contexts"):             self.writeline("__attr __tmp_contexts[%d];" % targets)          # Add temporary variable usage details.          if self.uses_temp(name, "__tmp_private_context"):             self.writeline("__attr __tmp_private_context;")         if self.uses_temp(name, "__tmp_value"):             self.writeline("__attr __tmp_value;")         if self.uses_temp(name, "__tmp_target_value"):             self.writeline("__attr __tmp_target_value;")         if self.uses_temp(name, "__tmp_result"):             self.writeline("__attr __tmp_result;")          module = self.importer.get_module(self.name)          if name in module.exception_namespaces:             self.writeline("__exc __tmp_exc;")      def start_if(self, first, test_ref):         statement = "%sif" % (not first and "else " or "")          # Consume logical results directly.          if isinstance(test_ref, LogicalResult):             self.writeline("%s %s" % (statement, test_ref.apply_test()))             temps = test_ref.discards_temporary()             if temps:                 self.remove_temps(temps)         else:             self.writeline("%s (__BOOL(%s))" % (statement, test_ref))          self.writeline("{")         self.indent += 1      def end_if(self):         self.indent -= 1         self.writeline("}")      def start_else(self):         self.writeline("else")         self.writeline("{")         self.indent += 1      def end_else(self):         self.indent -= 1         self.writeline("}")      def statement(self, expr):         s = str(expr)         if s:             self.writestmt("%s;" % s)      def statements(self, results):         for result in results:             self.statement(result)      def writeline(self, s):         print >>self.out, "%s%s" % (self.pad(), self.indenttext(s, self.indent + 1))      def writestmt(self, s):         self.writeline(s)      def write_comment(self, s):         self.writestmt("/* %s */" % s)      def pad(self, extra=0):         return (self.indent + extra) * self.tabstop      def indenttext(self, s, levels):         lines = s.split("\n")         out = [lines[0]]         for line in lines[1:]:             out.append(levels * self.tabstop + line)             if line.endswith("("):                 levels += 1             elif line.startswith(")"):                 levels -= 1         return "\n".join(out)  # vim: tabstop=4 expandtab shiftwidth=4