text: # -*- coding: utf-8 -*-
  """
      jinja2.compiler
      ~~~~~~~~~~~~~~~
  
      Compiles nodes into python code.
  
      :copyright: (c) 2010 by the Jinja Team.
      :license: BSD, see LICENSE for more details.
  """
  from cStringIO import StringIO
  from itertools import chain
  from copy import deepcopy
  from jinja2 import nodes
  from jinja2.nodes import EvalContext
  from jinja2.visitor import NodeVisitor, NodeTransformer
  from jinja2.exceptions import TemplateAssertionError
  from jinja2.utils import Markup, concat, escape, is_python_keyword, next
  
  
  operators = {
      'eq':       '==',
      'ne':       '!=',
      'gt':       '>',
      'gteq':     '>=',
      'lt':       '<',
      'lteq':     '<=',
      'in':       'in',
      'notin':    'not in'
  }
  
  try:
      exec '(0 if 0 else 0)'
  except SyntaxError:
      have_condexpr = False
  else:
      have_condexpr = True
  
  
  # what method to iterate over items do we want to use for dict iteration
  # in generated code?  on 2.x let's go with iteritems, on 3.x with items
  if hasattr(dict, 'iteritems'):
      dict_item_iter = 'iteritems'
  else:
      dict_item_iter = 'items'
  
  
  # does if 0: dummy(x) get us x into the scope?
  def unoptimize_before_dead_code():
      x = 42
      def f():
          if 0: dummy(x)
      return f
  unoptimize_before_dead_code = bool(unoptimize_before_dead_code().func_closure)
  
  
  def generate(node, environment, name, filename, stream=None,
               defer_init=False):
      """Generate the python source for a node tree."""
      if not isinstance(node, nodes.Template):
          raise TypeError('Can\'t compile non template nodes')
      generator = CodeGenerator(environment, name, filename, stream, defer_init)
      generator.visit(node)
      if stream is None:
          return generator.stream.getvalue()
  
  
  def has_safe_repr(value):
      """Does the node have a safe representation?"""
      if value is None or value is NotImplemented or value is Ellipsis:
          return True
      if isinstance(value, (bool, int, long, float, complex, basestring,
                            xrange, Markup)):
          return True
      if isinstance(value, (tuple, list, set, frozenset)):
          for item in value:
              if not has_safe_repr(item):
                  return False
          return True
      elif isinstance(value, dict):
          for key, value in value.iteritems():
              if not has_safe_repr(key):
                  return False
              if not has_safe_repr(value):
                  return False
          return True
      return False
  
  
  def find_undeclared(nodes, names):
      """Check if the names passed are accessed undeclared.  The return value
      is a set of all the undeclared names from the sequence of names found.
      """
      visitor = UndeclaredNameVisitor(names)
      try:
          for node in nodes:
              visitor.visit(node)
      except VisitorExit:
          pass
      return visitor.undeclared
  
  
  class Identifiers(object):
      """Tracks the status of identifiers in frames."""
  
      def __init__(self):
          # variables that are known to be declared (probably from outer
          # frames or because they are special for the frame)
          self.declared = set()
  
          # undeclared variables from outer scopes
          self.outer_undeclared = set()
  
          # names that are accessed without being explicitly declared by
          # this one or any of the outer scopes.  Names can appear both in
          # declared and undeclared.
          self.undeclared = set()
  
          # names that are declared locally
          self.declared_locally = set()
  
          # names that are declared by parameters
          self.declared_parameter = set()
  
      def add_special(self, name):
          """Register a special name like `loop`."""
          self.undeclared.discard(name)
          self.declared.add(name)
  
      def is_declared(self, name, local_only=False):
          """Check if a name is declared in this or an outer scope."""
          if name in self.declared_locally or name in self.declared_parameter:
              return True
          if local_only:
              return False
          return name in self.declared
  
      def copy(self):
          return deepcopy(self)
  
  
  class Frame(object):
      """Holds compile time information for us."""
  
      def __init__(self, eval_ctx, parent=None):
          self.eval_ctx = eval_ctx
          self.identifiers = Identifiers()
  
          # a toplevel frame is the root + soft frames such as if conditions.
          self.toplevel = False
  
          # the root frame is basically just the outermost frame, so no if
          # conditions.  This information is used to optimize inheritance
          # situations.
          self.rootlevel = False
  
          # in some dynamic inheritance situations the compiler needs to add
          # write tests around output statements.
          self.require_output_check = parent and parent.require_output_check
  
          # inside some tags we are using a buffer rather than yield statements.
          # this for example affects {% filter %} or {% macro %}.  If a frame
          # is buffered this variable points to the name of the list used as
          # buffer.
          self.buffer = None
  
          # the name of the block we're in, otherwise None.
          self.block = parent and parent.block or None
  
          # a set of actually assigned names
          self.assigned_names = set()
  
          # the parent of this frame
          self.parent = parent
  
          if parent is not None:
              self.identifiers.declared.update(
                  parent.identifiers.declared |
                  parent.identifiers.declared_parameter |
                  parent.assigned_names
              )
              self.identifiers.outer_undeclared.update(
                  parent.identifiers.undeclared -
                  self.identifiers.declared
              )
              self.buffer = parent.buffer
  
      def copy(self):
          """Create a copy of the current one."""
          rv = object.__new__(self.__class__)
          rv.__dict__.update(self.__dict__)
          rv.identifiers = object.__new__(self.identifiers.__class__)
          rv.identifiers.__dict__.update(self.identifiers.__dict__)
          return rv
  
      def inspect(self, nodes, hard_scope=False):
          """Walk the node and check for identifiers.  If the scope is hard (eg:
          enforce on a python level) overrides from outer scopes are tracked
          differently.
          """
          visitor = FrameIdentifierVisitor(self.identifiers, hard_scope)
          for node in nodes:
              visitor.visit(node)
  
      def find_shadowed(self, extra=()):
          """Find all the shadowed names.  extra is an iterable of variables
          that may be defined with `add_special` which may occour scoped.
          """
          i = self.identifiers
          return (i.declared | i.outer_undeclared) & \
                 (i.declared_locally | i.declared_parameter) | \
                 set(x for x in extra if i.is_declared(x))
  
      def inner(self):
          """Return an inner frame."""
          return Frame(self.eval_ctx, self)
  
      def soft(self):
          """Return a soft frame.  A soft frame may not be modified as
          standalone thing as it shares the resources with the frame it
          was created of, but it's not a rootlevel frame any longer.
          """
          rv = self.copy()
          rv.rootlevel = False
          return rv
  
      __copy__ = copy
  
  
  class VisitorExit(RuntimeError):
      """Exception used by the `UndeclaredNameVisitor` to signal a stop."""
  
  
  class DependencyFinderVisitor(NodeVisitor):
      """A visitor that collects filter and test calls."""
  
      def __init__(self):
          self.filters = set()
          self.tests = set()
  
      def visit_Filter(self, node):
          self.generic_visit(node)
          self.filters.add(node.name)
  
      def visit_Test(self, node):
          self.generic_visit(node)
          self.tests.add(node.name)
  
      def visit_Block(self, node):
          """Stop visiting at blocks."""
  
  
  class UndeclaredNameVisitor(NodeVisitor):
      """A visitor that checks if a name is accessed without being
      declared.  This is different from the frame visitor as it will
      not stop at closure frames.
      """
  
      def __init__(self, names):
          self.names = set(names)
          self.undeclared = set()
  
      def visit_Name(self, node):
          if node.ctx == 'load' and node.name in self.names:
              self.undeclared.add(node.name)
              if self.undeclared == self.names:
                  raise VisitorExit()
          else:
              self.names.discard(node.name)
  
      def visit_Block(self, node):
          """Stop visiting a blocks."""
  
  
  class FrameIdentifierVisitor(NodeVisitor):
      """A visitor for `Frame.inspect`."""
  
      def __init__(self, identifiers, hard_scope):
          self.identifiers = identifiers
          self.hard_scope = hard_scope
  
      def visit_Name(self, node):
          """All assignments to names go through this function."""
          if node.ctx == 'store':
              self.identifiers.declared_locally.add(node.name)
          elif node.ctx == 'param':
              self.identifiers.declared_parameter.add(node.name)
          elif node.ctx == 'load' and not \
               self.identifiers.is_declared(node.name, self.hard_scope):
              self.identifiers.undeclared.add(node.name)
  
      def visit_If(self, node):
          self.visit(node.test)
          real_identifiers = self.identifiers
  
          old_names = real_identifiers.declared_locally | \
                      real_identifiers.declared_parameter
  
          def inner_visit(nodes):
              if not nodes:
                  return set()
              self.identifiers = real_identifiers.copy()
              for subnode in nodes:
                  self.visit(subnode)
              rv = self.identifiers.declared_locally - old_names
              # we have to remember the undeclared variables of this branch
              # because we will have to pull them.
              real_identifiers.undeclared.update(self.identifiers.undeclared)
              self.identifiers = real_identifiers
              return rv
  
          body = inner_visit(node.body)
          else_ = inner_visit(node.else_ or ())
  
          # the differences between the two branches are also pulled as
          # undeclared variables
          real_identifiers.undeclared.update(body.symmetric_difference(else_) -
                                             real_identifiers.declared)
  
          # remember those that are declared.
          real_identifiers.declared_locally.update(body | else_)
  
      def visit_Macro(self, node):
          self.identifiers.declared_locally.add(node.name)
  
      def visit_Import(self, node):
          self.generic_visit(node)
          self.identifiers.declared_locally.add(node.target)
  
      def visit_FromImport(self, node):
          self.generic_visit(node)
          for name in node.names:
              if isinstance(name, tuple):
                  self.identifiers.declared_locally.add(name[1])
              else:
                  self.identifiers.declared_locally.add(name)
  
      def visit_Assign(self, node):
          """Visit assignments in the correct order."""
          self.visit(node.node)
          self.visit(node.target)
  
      def visit_For(self, node):
          """Visiting stops at for blocks.  However the block sequence
          is visited as part of the outer scope.
          """
          self.visit(node.iter)
  
      def visit_CallBlock(self, node):
          self.visit(node.call)
  
      def visit_FilterBlock(self, node):
          self.visit(node.filter)
  
      def visit_Scope(self, node):
          """Stop visiting at scopes."""
  
      def visit_Block(self, node):
          """Stop visiting at blocks."""
  
  
  class CompilerExit(Exception):
      """Raised if the compiler encountered a situation where it just
      doesn't make sense to further process the code.  Any block that
      raises such an exception is not further processed.
      """
  
  
  class CodeGenerator(NodeVisitor):
  
      def __init__(self, environment, name, filename, stream=None,
                   defer_init=False):
          if stream is None:
              stream = StringIO()
          self.environment = environment
          self.name = name
          self.filename = filename
          self.stream = stream
          self.created_block_context = False
          self.defer_init = defer_init
  
          # aliases for imports
          self.import_aliases = {}
  
          # a registry for all blocks.  Because blocks are moved out
          # into the global python scope they are registered here
          self.blocks = {}
  
          # the number of extends statements so far
          self.extends_so_far = 0
  
          # some templates have a rootlevel extends.  In this case we
          # can safely assume that we're a child template and do some
          # more optimizations.
          self.has_known_extends = False
  
          # the current line number
          self.code_lineno = 1
  
          # registry of all filters and tests (global, not block local)
          self.tests = {}
          self.filters = {}
  
          # the debug information
          self.debug_info = []
          self._write_debug_info = None
  
          # the number of new lines before the next write()
          self._new_lines = 0
  
          # the line number of the last written statement
          self._last_line = 0
  
          # true if nothing was written so far.
          self._first_write = True
  
          # used by the `temporary_identifier` method to get new
          # unique, temporary identifier
          self._last_identifier = 0
  
          # the current indentation
          self._indentation = 0
  
      # -- Various compilation helpers
  
      def fail(self, msg, lineno):
          """Fail with a :exc:`TemplateAssertionError`."""
          raise TemplateAssertionError(msg, lineno, self.name, self.filename)
  
      def temporary_identifier(self):
          """Get a new unique identifier."""
          self._last_identifier += 1
          return 't_%d' % self._last_identifier
  
      def buffer(self, frame):
          """Enable buffering for the frame from that point onwards."""
          frame.buffer = self.temporary_identifier()
          self.writeline('%s = []' % frame.buffer)
  
      def return_buffer_contents(self, frame):
          """Return the buffer contents of the frame."""
          if frame.eval_ctx.volatile:
              self.writeline('if context.eval_ctx.autoescape:')
              self.indent()
              self.writeline('return Markup(concat(%s))' % frame.buffer)
              self.outdent()
              self.writeline('else:')
              self.indent()
              self.writeline('return concat(%s)' % frame.buffer)
              self.outdent()
          elif frame.eval_ctx.autoescape:
              self.writeline('return Markup(concat(%s))' % frame.buffer)
          else:
              self.writeline('return concat(%s)' % frame.buffer)
  
      def indent(self):
          """Indent by one."""
          self._indentation += 1
  
      def outdent(self, step=1):
          """Outdent by step."""
          self._indentation -= step
  
      def start_write(self, frame, node=None):
          """Yield or write into the frame buffer."""
          if frame.buffer is None:
              self.writeline('yield ', node)
          else:
              self.writeline('%s.append(' % frame.buffer, node)
  
      def end_write(self, frame):
          """End the writing process started by `start_write`."""
          if frame.buffer is not None:
              self.write(')')
  
      def simple_write(self, s, frame, node=None):
          """Simple shortcut for start_write + write + end_write."""
          self.start_write(frame, node)
          self.write(s)
          self.end_write(frame)
  
      def blockvisit(self, nodes, frame):
          """Visit a list of nodes as block in a frame.  If the current frame
          is no buffer a dummy ``if 0: yield None`` is written automatically
          unless the force_generator parameter is set to False.
          """
          if frame.buffer is None:
              self.writeline('if 0: yield None')
          else:
              self.writeline('pass')
          try:
              for node in nodes:
                  self.visit(node, frame)
          except CompilerExit:
              pass
  
      def write(self, x):
          """Write a string into the output stream."""
          if self._new_lines:
              if not self._first_write:
                  self.stream.write('\n' * self._new_lines)
                  self.code_lineno += self._new_lines
                  if self._write_debug_info is not None:
                      self.debug_info.append((self._write_debug_info,
                                              self.code_lineno))
                      self._write_debug_info = None
              self._first_write = False
              self.stream.write('    ' * self._indentation)
              self._new_lines = 0
          self.stream.write(x)
  
      def writeline(self, x, node=None, extra=0):
          """Combination of newline and write."""
          self.newline(node, extra)
          self.write(x)
  
      def newline(self, node=None, extra=0):
          """Add one or more newlines before the next write."""
          self._new_lines = max(self._new_lines, 1 + extra)
          if node is not None and node.lineno != self._last_line:
              self._write_debug_info = node.lineno
              self._last_line = node.lineno
  
      def signature(self, node, frame, extra_kwargs=None):
          """Writes a function call to the stream for the current node.
          A leading comma is added automatically.  The extra keyword
          arguments may not include python keywords otherwise a syntax
          error could occour.  The extra keyword arguments should be given
          as python dict.
          """
          # if any of the given keyword arguments is a python keyword
          # we have to make sure that no invalid call is created.
          kwarg_workaround = False
          for kwarg in chain((x.key for x in node.kwargs), extra_kwargs or ()):
              if is_python_keyword(kwarg):
                  kwarg_workaround = True
                  break
  
          for arg in node.args:
              self.write(', ')
              self.visit(arg, frame)
  
          if not kwarg_workaround:
              for kwarg in node.kwargs:
                  self.write(', ')
                  self.visit(kwarg, frame)
              if extra_kwargs is not None:
                  for key, value in extra_kwargs.iteritems():
                      self.write(', %s=%s' % (key, value))
          if node.dyn_args:
              self.write(', *')
              self.visit(node.dyn_args, frame)
  
          if kwarg_workaround:
              if node.dyn_kwargs is not None:
                  self.write(', **dict({')
              else:
                  self.write(', **{')
              for kwarg in node.kwargs:
                  self.write('%r: ' % kwarg.key)
                  self.visit(kwarg.value, frame)
                  self.write(', ')
              if extra_kwargs is not None:
                  for key, value in extra_kwargs.iteritems():
                      self.write('%r: %s, ' % (key, value))
              if node.dyn_kwargs is not None:
                  self.write('}, **')
                  self.visit(node.dyn_kwargs, frame)
                  self.write(')')
              else:
                  self.write('}')
  
          elif node.dyn_kwargs is not None:
              self.write(', **')
              self.visit(node.dyn_kwargs, frame)
  
      def pull_locals(self, frame):
          """Pull all the references identifiers into the local scope."""
          for name in frame.identifiers.undeclared:
              self.writeline('l_%s = context.resolve(%r)' % (name, name))
  
      def pull_dependencies(self, nodes):
          """Pull all the dependencies."""
          visitor = DependencyFinderVisitor()
          for node in nodes:
              visitor.visit(node)
          for dependency in 'filters', 'tests':
              mapping = getattr(self, dependency)
              for name in getattr(visitor, dependency):
                  if name not in mapping:
                      mapping[name] = self.temporary_identifier()
                  self.writeline('%s = environment.%s[%r]' %
                                 (mapping[name], dependency, name))
  
      def unoptimize_scope(self, frame):
          """Disable Python optimizations for the frame."""
          # XXX: this is not that nice but it has no real overhead.  It
          # mainly works because python finds the locals before dead code
          # is removed.  If that breaks we have to add a dummy function
          # that just accepts the arguments and does nothing.
          if frame.identifiers.declared:
              self.writeline('%sdummy(%s)' % (
                  unoptimize_before_dead_code and 'if 0: ' or '',
                  ', '.join('l_' + name for name in frame.identifiers.declared)
              ))
  
      def push_scope(self, frame, extra_vars=()):
          """This function returns all the shadowed variables in a dict
          in the form name: alias and will write the required assignments
          into the current scope.  No indentation takes place.
  
          This also predefines locally declared variables from the loop
          body because under some circumstances it may be the case that
  
          `extra_vars` is passed to `Frame.find_shadowed`.
          """
          aliases = {}
          for name in frame.find_shadowed(extra_vars):
              aliases[name] = ident = self.temporary_identifier()
              self.writeline('%s = l_%s' % (ident, name))
          to_declare = set()
          for name in frame.identifiers.declared_locally:
              if name not in aliases:
                  to_declare.add('l_' + name)
          if to_declare:
              self.writeline(' = '.join(to_declare) + ' = missing')
          return aliases
  
      def pop_scope(self, aliases, frame):
          """Restore all aliases and delete unused variables."""
          for name, alias in aliases.iteritems():
              self.writeline('l_%s = %s' % (name, alias))
          to_delete = set()
          for name in frame.identifiers.declared_locally:
              if name not in aliases:
                  to_delete.add('l_' + name)
          if to_delete:
              # we cannot use the del statement here because enclosed
              # scopes can trigger a SyntaxError:
              #   a = 42; b = lambda: a; del a
              self.writeline(' = '.join(to_delete) + ' = missing')
  
      def function_scoping(self, node, frame, children=None,
                           find_special=True):
          """In Jinja a few statements require the help of anonymous
          functions.  Those are currently macros and call blocks and in
          the future also recursive loops.  As there is currently
          technical limitation that doesn't allow reading and writing a
          variable in a scope where the initial value is coming from an
          outer scope, this function tries to fall back with a common
          error message.  Additionally the frame passed is modified so
          that the argumetns are collected and callers are looked up.
  
          This will return the modified frame.
          """
          # we have to iterate twice over it, make sure that works
          if children is None:
              children = node.iter_child_nodes()
          children = list(children)
          func_frame = frame.inner()
          func_frame.inspect(children, hard_scope=True)
  
          # variables that are undeclared (accessed before declaration) and
          # declared locally *and* part of an outside scope raise a template
          # assertion error. Reason: we can't generate reasonable code from
          # it without aliasing all the variables.
          # this could be fixed in Python 3 where we have the nonlocal
          # keyword or if we switch to bytecode generation
          overriden_closure_vars = (
              func_frame.identifiers.undeclared &
              func_frame.identifiers.declared &
              (func_frame.identifiers.declared_locally |
               func_frame.identifiers.declared_parameter)
          )
          if overriden_closure_vars:
              self.fail('It\'s not possible to set and access variables '
                        'derived from an outer scope! (affects: %s)' %
                        ', '.join(sorted(overriden_closure_vars)), node.lineno)
  
          # remove variables from a closure from the frame's undeclared
          # identifiers.
          func_frame.identifiers.undeclared -= (
              func_frame.identifiers.undeclared &
              func_frame.identifiers.declared
          )
  
          # no special variables for this scope, abort early
          if not find_special:
              return func_frame
  
          func_frame.accesses_kwargs = False
          func_frame.accesses_varargs = False
          func_frame.accesses_caller = False
          func_frame.arguments = args = ['l_' + x.name for x in node.args]
  
          undeclared = find_undeclared(children, ('caller', 'kwargs', 'varargs'))
  
          if 'caller' in undeclared:
              func_frame.accesses_caller = True
              func_frame.identifiers.add_special('caller')
              args.append('l_caller')
          if 'kwargs' in undeclared:
              func_frame.accesses_kwargs = True
              func_frame.identifiers.add_special('kwargs')
              args.append('l_kwargs')
          if 'varargs' in undeclared:
              func_frame.accesses_varargs = True
              func_frame.identifiers.add_special('varargs')
              args.append('l_varargs')
          return func_frame
  
      def macro_body(self, node, frame, children=None):
          """Dump the function def of a macro or call block."""
          frame = self.function_scoping(node, frame, children)
          # macros are delayed, they never require output checks
          frame.require_output_check = False
          args = frame.arguments
          # XXX: this is an ugly fix for the loop nesting bug
          # (tests.test_old_bugs.test_loop_call_bug).  This works around
          # a identifier nesting problem we have in general.  It's just more
          # likely to happen in loops which is why we work around it.  The
          # real solution would be "nonlocal" all the identifiers that are
          # leaking into a new python frame and might be used both unassigned
          # and assigned.
          if 'loop' in frame.identifiers.declared:
              args = args + ['l_loop=l_loop']
          self.writeline('def macro(%s):' % ', '.join(args), node)
          self.indent()
          self.buffer(frame)
          self.pull_locals(frame)
          self.blockvisit(node.body, frame)
          self.return_buffer_contents(frame)
          self.outdent()
          return frame
  
      def macro_def(self, node, frame):
          """Dump the macro definition for the def created by macro_body."""
          arg_tuple = ', '.join(repr(x.name) for x in node.args)
          name = getattr(node, 'name', None)
          if len(node.args) == 1:
              arg_tuple += ','
          self.write('Macro(environment, macro, %r, (%s), (' %
                     (name, arg_tuple))
          for arg in node.defaults:
              self.visit(arg, frame)
              self.write(', ')
          self.write('), %r, %r, %r)' % (
              bool(frame.accesses_kwargs),
              bool(frame.accesses_varargs),
              bool(frame.accesses_caller)
          ))
  
      def position(self, node):
          """Return a human readable position for the node."""
          rv = 'line %d' % node.lineno
          if self.name is not None:
              rv += ' in ' + repr(self.name)
          return rv
  
      # -- Statement Visitors
  
      def visit_Template(self, node, frame=None):
          assert frame is None, 'no root frame allowed'
          eval_ctx = EvalContext(self.environment, self.name)
  
          from jinja2.runtime import __all__ as exported
          self.writeline('from __future__ import division')
          self.writeline('from jinja2.runtime import ' + ', '.join(exported))
          if not unoptimize_before_dead_code:
              self.writeline('dummy = lambda *x: None')
  
          # if we want a deferred initialization we cannot move the
          # environment into a local name
          envenv = not self.defer_init and ', environment=environment' or ''
  
          # do we have an extends tag at all?  If not, we can save some
          # overhead by just not processing any inheritance code.
          have_extends = node.find(nodes.Extends) is not None
  
          # find all blocks
          for block in node.find_all(nodes.Block):
              if block.name in self.blocks:
                  self.fail('block %r defined twice' % block.name, block.lineno)
              self.blocks[block.name] = block
  
          # find all imports and import them
          for import_ in node.find_all(nodes.ImportedName):
              if import_.importname not in self.import_aliases:
                  imp = import_.importname
                  self.import_aliases[imp] = alias = self.temporary_identifier()
                  if '.' in imp:
                      module, obj = imp.rsplit('.', 1)
                      self.writeline('from %s import %s as %s' %
                                     (module, obj, alias))
                  else:
                      self.writeline('import %s as %s' % (imp, alias))
  
          # add the load name
          self.writeline('name = %r' % self.name)
  
          # generate the root render function.
          self.writeline('def root(context%s):' % envenv, extra=1)
  
          # process the root
          frame = Frame(eval_ctx)
          frame.inspect(node.body)
          frame.toplevel = frame.rootlevel = True
          frame.require_output_check = have_extends and not self.has_known_extends
          self.indent()
          if have_extends:
              self.writeline('parent_template = None')
          if 'self' in find_undeclared(node.body, ('self',)):
              frame.identifiers.add_special('self')
              self.writeline('l_self = TemplateReference(context)')
          self.pull_locals(frame)
          self.pull_dependencies(node.body)
          self.blockvisit(node.body, frame)
          self.outdent()
  
          # make sure that the parent root is called.
          if have_extends:
              if not self.has_known_extends:
                  self.indent()
                  self.writeline('if parent_template is not None:')
              self.indent()
              self.writeline('for event in parent_template.'
                             'root_render_func(context):')
              self.indent()
              self.writeline('yield event')
              self.outdent(2 + (not self.has_known_extends))
  
          # at this point we now have the blocks collected and can visit them too.
          for name, block in self.blocks.iteritems():
              block_frame = Frame(eval_ctx)
              block_frame.inspect(block.body)
              block_frame.block = name
              self.writeline('def block_%s(context%s):' % (name, envenv),
                             block, 1)
              self.indent()
              undeclared = find_undeclared(block.body, ('self', 'super'))
              if 'self' in undeclared:
                  block_frame.identifiers.add_special('self')
                  self.writeline('l_self = TemplateReference(context)')
              if 'super' in undeclared:
                  block_frame.identifiers.add_special('super')
                  self.writeline('l_super = context.super(%r, '
                                 'block_%s)' % (name, name))
              self.pull_locals(block_frame)
              self.pull_dependencies(block.body)
              self.blockvisit(block.body, block_frame)
              self.outdent()
  
          self.writeline('blocks = {%s}' % ', '.join('%r: block_%s' % (x, x)
                                                     for x in self.blocks),
                         extra=1)
  
          # add a function that returns the debug info
          self.writeline('debug_info = %r' % '&'.join('%s=%s' % x for x
                                                      in self.debug_info))
  
      def visit_Block(self, node, frame):
          """Call a block and register it for the template."""
          level = 1
          if frame.toplevel:
              # if we know that we are a child template, there is no need to
              # check if we are one
              if self.has_known_extends:
                  return
              if self.extends_so_far > 0:
                  self.writeline('if parent_template is None:')
                  self.indent()
                  level += 1
          context = node.scoped and 'context.derived(locals())' or 'context'
          self.writeline('for event in context.blocks[%r][0](%s):' % (
                         node.name, context), node)
          self.indent()
          self.simple_write('event', frame)
          self.outdent(level)
  
      def visit_Extends(self, node, frame):
          """Calls the extender."""
          if not frame.toplevel:
              self.fail('cannot use extend from a non top-level scope',
                        node.lineno)
  
          # if the number of extends statements in general is zero so
          # far, we don't have to add a check if something extended
          # the template before this one.
          if self.extends_so_far > 0:
  
              # if we have a known extends we just add a template runtime
              # error into the generated code.  We could catch that at compile
              # time too, but i welcome it not to confuse users by throwing the
              # same error at different times just "because we can".
              if not self.has_known_extends:
                  self.writeline('if parent_template is not None:')
                  self.indent()
              self.writeline('raise TemplateRuntimeError(%r)' %
                             'extended multiple times')
              self.outdent()
  
              # if we have a known extends already we don't need that code here
              # as we know that the template execution will end here.
              if self.has_known_extends:
                  raise CompilerExit()
  
          self.writeline('parent_template = environment.get_template(', node)
          self.visit(node.template, frame)
          self.write(', %r)' % self.name)
          self.writeline('for name, parent_block in parent_template.'
                         'blocks.%s():' % dict_item_iter)
          self.indent()
          self.writeline('context.blocks.setdefault(name, []).'
                         'append(parent_block)')
          self.outdent()
  
          # if this extends statement was in the root level we can take
          # advantage of that information and simplify the generated code
          # in the top level from this point onwards
          if frame.rootlevel:
              self.has_known_extends = True
  
          # and now we have one more
          self.extends_so_far += 1
  
      def visit_Include(self, node, frame):
          """Handles includes."""
          if node.with_context:
              self.unoptimize_scope(frame)
          if node.ignore_missing:
              self.writeline('try:')
              self.indent()
  
          func_name = 'get_or_select_template'
          if isinstance(node.template, nodes.Const):
              if isinstance(node.template.value, basestring):
                  func_name = 'get_template'
              elif isinstance(node.template.value, (tuple, list)):
                  func_name = 'select_template'
          elif isinstance(node.template, (nodes.Tuple, nodes.List)):
              func_name = 'select_template'
  
          self.writeline('template = environment.%s(' % func_name, node)
          self.visit(node.template, frame)
          self.write(', %r)' % self.name)
          if node.ignore_missing:
              self.outdent()
              self.writeline('except TemplateNotFound:')
              self.indent()
              self.writeline('pass')
              self.outdent()
              self.writeline('else:')
              self.indent()
  
          if node.with_context:
              self.writeline('for event in template.root_render_func('
                             'template.new_context(context.parent, True, '
                             'locals())):')
          else:
              self.writeline('for event in template.module._body_stream:')
  
          self.indent()
          self.simple_write('event', frame)
          self.outdent()
  
          if node.ignore_missing:
              self.outdent()
  
      def visit_Import(self, node, frame):
          """Visit regular imports."""
          if node.with_context:
              self.unoptimize_scope(frame)
          self.writeline('l_%s = ' % node.target, node)
          if frame.toplevel:
              self.write('context.vars[%r] = ' % node.target)
          self.write('environment.get_template(')
          self.visit(node.template, frame)
          self.write(', %r).' % self.name)
          if node.with_context:
              self.write('make_module(context.parent, True, locals())')
          else:
              self.write('module')
          if frame.toplevel and not node.target.startswith('_'):
              self.writeline('context.exported_vars.discard(%r)' % node.target)
          frame.assigned_names.add(node.target)
  
      def visit_FromImport(self, node, frame):
          """Visit named imports."""
          self.newline(node)
          self.write('included_template = environment.get_template(')
          self.visit(node.template, frame)
          self.write(', %r).' % self.name)
          if node.with_context:
              self.write('make_module(context.parent, True)')
          else:
              self.write('module')
  
          var_names = []
          discarded_names = []
          for name in node.names:
              if isinstance(name, tuple):
                  name, alias = name
              else:
                  alias = name
              self.writeline('l_%s = getattr(included_template, '
                             '%r, missing)' % (alias, name))
              self.writeline('if l_%s is missing:' % alias)
              self.indent()
              self.writeline('l_%s = environment.undefined(%r %% '
                             'included_template.__name__, '
                             'name=%r)' %
                             (alias, 'the template %%r (imported on %s) does '
                             'not export the requested name %s' % (
                                  self.position(node),
                                  repr(name)
                             ), name))
              self.outdent()
              if frame.toplevel:
                  var_names.append(alias)
                  if not alias.startswith('_'):
                      discarded_names.append(alias)
              frame.assigned_names.add(alias)
  
          if var_names:
              if len(var_names) == 1:
                  name = var_names[0]
                  self.writeline('context.vars[%r] = l_%s' % (name, name))
              else:
                  self.writeline('context.vars.update({%s})' % ', '.join(
                      '%r: l_%s' % (name, name) for name in var_names
                  ))
          if discarded_names:
              if len(discarded_names) == 1:
                  self.writeline('context.exported_vars.discard(%r)' %
                                 discarded_names[0])
              else:
                  self.writeline('context.exported_vars.difference_'
                                 'update((%s))' % ', '.join(map(repr, discarded_names)))
  
      def visit_For(self, node, frame):
          # when calculating the nodes for the inner frame we have to exclude
          # the iterator contents from it
          children = node.iter_child_nodes(exclude=('iter',))
          if node.recursive:
              loop_frame = self.function_scoping(node, frame, children,
                                                 find_special=False)
          else:
              loop_frame = frame.inner()
              loop_frame.inspect(children)
  
          # try to figure out if we have an extended loop.  An extended loop
          # is necessary if the loop is in recursive mode if the special loop
          # variable is accessed in the body.
          extended_loop = node.recursive or 'loop' in \
                          find_undeclared(node.iter_child_nodes(
                              only=('body',)), ('loop',))
  
          # if we don't have an recursive loop we have to find the shadowed
          # variables at that point.  Because loops can be nested but the loop
          # variable is a special one we have to enforce aliasing for it.
          if not node.recursive:
              aliases = self.push_scope(loop_frame, ('loop',))
  
          # otherwise we set up a buffer and add a function def
          else:
              self.writeline('def loop(reciter, loop_render_func):', node)
              self.indent()
              self.buffer(loop_frame)
              aliases = {}
  
          # make sure the loop variable is a special one and raise a template
          # assertion error if a loop tries to write to loop
          if extended_loop:
              loop_frame.identifiers.add_special('loop')
          for name in node.find_all(nodes.Name):
              if name.ctx == 'store' and name.name == 'loop':
                  self.fail('Can\'t assign to special loop variable '
                            'in for-loop target', name.lineno)
  
          self.pull_locals(loop_frame)
          if node.else_:
              iteration_indicator = self.temporary_identifier()
              self.writeline('%s = 1' % iteration_indicator)
  
          # Create a fake parent loop if the else or test section of a
          # loop is accessing the special loop variable and no parent loop
          # exists.
          if 'loop' not in aliases and 'loop' in find_undeclared(
             node.iter_child_nodes(only=('else_', 'test')), ('loop',)):
              self.writeline("l_loop = environment.undefined(%r, name='loop')" %
                  ("'loop' is undefined. the filter section of a loop as well "
                   "as the else block doesn't have access to the special 'loop'"
                   " variable of the current loop.  Because there is no parent "
                   "loop it's undefined.  Happened in loop on %s" %
                   self.position(node)))
  
          self.writeline('for ', node)
          self.visit(node.target, loop_frame)
          self.write(extended_loop and ', l_loop in LoopContext(' or ' in ')
  
          # if we have an extened loop and a node test, we filter in the
          # "outer frame".
          if extended_loop and node.test is not None:
              self.write('(')
              self.visit(node.target, loop_frame)
              self.write(' for ')
              self.visit(node.target, loop_frame)
              self.write(' in ')
              if node.recursive:
                  self.write('reciter')
              else:
                  self.visit(node.iter, loop_frame)
              self.write(' if (')
              test_frame = loop_frame.copy()
              self.visit(node.test, test_frame)
              self.write('))')
  
          elif node.recursive:
              self.write('reciter')
          else:
              self.visit(node.iter, loop_frame)
  
          if node.recursive:
              self.write(', recurse=loop_render_func):')
          else:
              self.write(extended_loop and '):' or ':')
  
          # tests in not extended loops become a continue
          if not extended_loop and node.test is not None:
              self.indent()
              self.writeline('if not ')
              self.visit(node.test, loop_frame)
              self.write(':')
              self.indent()
              self.writeline('continue')
              self.outdent(2)
  
          self.indent()
          self.blockvisit(node.body, loop_frame)
          if node.else_:
              self.writeline('%s = 0' % iteration_indicator)
          self.outdent()
  
          if node.else_:
              self.writeline('if %s:' % iteration_indicator)
              self.indent()
              self.blockvisit(node.else_, loop_frame)
              self.outdent()
  
          # reset the aliases if there are any.
          if not node.recursive:
              self.pop_scope(aliases, loop_frame)
  
          # if the node was recursive we have to return the buffer contents
          # and start the iteration code
          if node.recursive:
              self.return_buffer_contents(loop_frame)
              self.outdent()
              self.start_write(frame, node)
              self.write('loop(')
              self.visit(node.iter, frame)
              self.write(', loop)')
              self.end_write(frame)
  
      def visit_If(self, node, frame):
          if_frame = frame.soft()
          self.writeline('if ', node)
          self.visit(node.test, if_frame)
          self.write(':')
          self.indent()
          self.blockvisit(node.body, if_frame)
          self.outdent()
          if node.else_:
              self.writeline('else:')
              self.indent()
              self.blockvisit(node.else_, if_frame)
              self.outdent()
  
      def visit_Macro(self, node, frame):
          macro_frame = self.macro_body(node, frame)
          self.newline()
          if frame.toplevel:
              if not node.name.startswith('_'):
                  self.write('context.exported_vars.add(%r)' % node.name)
              self.writeline('context.vars[%r] = ' % node.name)
          self.write('l_%s = ' % node.name)
          self.macro_def(node, macro_frame)
          frame.assigned_names.add(node.name)
  
      def visit_CallBlock(self, node, frame):
          children = node.iter_child_nodes(exclude=('call',))
          call_frame = self.macro_body(node, frame, children)
          self.writeline('caller = ')
          self.macro_def(node, call_frame)
          self.start_write(frame, node)
          self.visit_Call(node.call, call_frame, forward_caller=True)
          self.end_write(frame)
  
      def visit_FilterBlock(self, node, frame):
          filter_frame = frame.inner()
          filter_frame.inspect(node.iter_child_nodes())
          aliases = self.push_scope(filter_frame)
          self.pull_locals(filter_frame)
          self.buffer(filter_frame)
          self.blockvisit(node.body, filter_frame)
          self.start_write(frame, node)
          self.visit_Filter(node.filter, filter_frame)
          self.end_write(frame)
          self.pop_scope(aliases, filter_frame)
  
      def visit_ExprStmt(self, node, frame):
          self.newline(node)
          self.visit(node.node, frame)
  
      def visit_Output(self, node, frame):
          # if we have a known extends statement, we don't output anything
          # if we are in a require_output_check section
          if self.has_known_extends and frame.require_output_check:
              return
  
          if self.environment.finalize:
              finalize = lambda x: unicode(self.environment.finalize(x))
          else:
              finalize = unicode
  
          # if we are inside a frame that requires output checking, we do so
          outdent_later = False
          if frame.require_output_check:
              self.writeline('if parent_template is None:')
              self.indent()
              outdent_later = True
  
          # try to evaluate as many chunks as possible into a static
          # string at compile time.
          body = []
          for child in node.nodes:
              try:
                  const = child.as_const(frame.eval_ctx)
              except nodes.Impossible:
                  body.append(child)
                  continue
              # the frame can't be volatile here, becaus otherwise the
              # as_const() function would raise an Impossible exception
              # at that point.
              try:
                  if frame.eval_ctx.autoescape:
                      if hasattr(const, '__html__'):
                          const = const.__html__()
                      else:
                          const = escape(const)
                  const = finalize(const)
              except:
                  # if something goes wrong here we evaluate the node
                  # at runtime for easier debugging
                  body.append(child)
                  continue
              if body and isinstance(body[-1], list):
                  body[-1].append(const)
              else:
                  body.append([const])
  
          # if we have less than 3 nodes or a buffer we yield or extend/append
          if len(body) < 3 or frame.buffer is not None:
              if frame.buffer is not None:
                  # for one item we append, for more we extend
                  if len(body) == 1:
                      self.writeline('%s.append(' % frame.buffer)
                  else:
                      self.writeline('%s.extend((' % frame.buffer)
                  self.indent()
              for item in body:
                  if isinstance(item, list):
                      val = repr(concat(item))
                      if frame.buffer is None:
                          self.writeline('yield ' + val)
                      else:
                          self.writeline(val + ', ')
                  else:
                      if frame.buffer is None:
                          self.writeline('yield ', item)
                      else:
                          self.newline(item)
                      close = 1
                      if frame.eval_ctx.volatile:
                          self.write('(context.eval_ctx.autoescape and'
                                     ' escape or to_string)(')
                      elif frame.eval_ctx.autoescape:
                          self.write('escape(')
                      else:
                          self.write('to_string(')
                      if self.environment.finalize is not None:
                          self.write('environment.finalize(')
                          close += 1
                      self.visit(item, frame)
                      self.write(')' * close)
                      if frame.buffer is not None:
                          self.write(', ')
              if frame.buffer is not None:
                  # close the open parentheses
                  self.outdent()
                  self.writeline(len(body) == 1 and ')' or '))')
  
          # otherwise we create a format string as this is faster in that case
          else:
              format = []
              arguments = []
              for item in body:
                  if isinstance(item, list):
                      format.append(concat(item).replace('%', '%%'))
                  else:
                      format.append('%s')
                      arguments.append(item)
              self.writeline('yield ')
              self.write(repr(concat(format)) + ' % (')
              idx = -1
              self.indent()
              for argument in arguments:
                  self.newline(argument)
                  close = 0
                  if frame.eval_ctx.volatile:
                      self.write('(context.eval_ctx.autoescape and'
                                 ' escape or to_string)(')
                      close += 1
                  elif frame.eval_ctx.autoescape:
                      self.write('escape(')
                      close += 1
                  if self.environment.finalize is not None:
                      self.write('environment.finalize(')
                      close += 1
                  self.visit(argument, frame)
                  self.write(')' * close + ', ')
              self.outdent()
              self.writeline(')')
  
          if outdent_later:
              self.outdent()
  
      def visit_Assign(self, node, frame):
          self.newline(node)
          # toplevel assignments however go into the local namespace and
          # the current template's context.  We create a copy of the frame
          # here and add a set so that the Name visitor can add the assigned
          # names here.
          if frame.toplevel:
              assignment_frame = frame.copy()
              assignment_frame.toplevel_assignments = set()
          else:
              assignment_frame = frame
          self.visit(node.target, assignment_frame)
          self.write(' = ')
          self.visit(node.node, frame)
  
          # make sure toplevel assignments are added to the context.
          if frame.toplevel:
              public_names = [x for x in assignment_frame.toplevel_assignments
                              if not x.startswith('_')]
              if len(assignment_frame.toplevel_assignments) == 1:
                  name = next(iter(assignment_frame.toplevel_assignments))
                  self.writeline('context.vars[%r] = l_%s' % (name, name))
              else:
                  self.writeline('context.vars.update({')
                  for idx, name in enumerate(assignment_frame.toplevel_assignments):
                      if idx:
                          self.write(', ')
                      self.write('%r: l_%s' % (name, name))
                  self.write('})')
              if public_names:
                  if len(public_names) == 1:
                      self.writeline('context.exported_vars.add(%r)' %
                                     public_names[0])
                  else:
                      self.writeline('context.exported_vars.update((%s))' %
                                     ', '.join(map(repr, public_names)))
  
      # -- Expression Visitors
  
      def visit_Name(self, node, frame):
          if node.ctx == 'store' and frame.toplevel:
              frame.toplevel_assignments.add(node.name)
          self.write('l_' + node.name)
          frame.assigned_names.add(node.name)
  
      def visit_Const(self, node, frame):
          val = node.value
          if isinstance(val, float):
              self.write(str(val))
          else:
              self.write(repr(val))
  
      def visit_TemplateData(self, node, frame):
          try:
              self.write(repr(node.as_const(frame.eval_ctx)))
          except nodes.Impossible:
              self.write('(context.eval_ctx.autoescape and Markup or identity)(%r)'
                         % node.data)
  
      def visit_Tuple(self, node, frame):
          self.write('(')
          idx = -1
          for idx, item in enumerate(node.items):
              if idx:
                  self.write(', ')
              self.visit(item, frame)
          self.write(idx == 0 and ',)' or ')')
  
      def visit_List(self, node, frame):
          self.write('[')
          for idx, item in enumerate(node.items):
              if idx:
                  self.write(', ')
              self.visit(item, frame)
          self.write(']')
  
      def visit_Dict(self, node, frame):
          self.write('{')
          for idx, item in enumerate(node.items):
              if idx:
                  self.write(', ')
              self.visit(item.key, frame)
              self.write(': ')
              self.visit(item.value, frame)
          self.write('}')
  
      def binop(operator):
          def visitor(self, node, frame):
              self.write('(')
              self.visit(node.left, frame)
              self.write(' %s ' % operator)
              self.visit(node.right, frame)
              self.write(')')
          return visitor
  
      def uaop(operator):
          def visitor(self, node, frame):
              self.write('(' + operator)
              self.visit(node.node, frame)
              self.write(')')
          return visitor
  
      visit_Add = binop('+')
      visit_Sub = binop('-')
      visit_Mul = binop('*')
      visit_Div = binop('/')
      visit_FloorDiv = binop('//')
      visit_Pow = binop('**')
      visit_Mod = binop('%')
      visit_And = binop('and')
      visit_Or = binop('or')
      visit_Pos = uaop('+')
      visit_Neg = uaop('-')
      visit_Not = uaop('not ')
      del binop, uaop
  
      def visit_Concat(self, node, frame):
          if frame.eval_ctx.volatile:
              func_name = '(context.eval_ctx.volatile and' \
                          ' markup_join or unicode_join)'
          elif frame.eval_ctx.autoescape:
              func_name = 'markup_join'
          else:
              func_name = 'unicode_join'
          self.write('%s((' % func_name)
          for arg in node.nodes:
              self.visit(arg, frame)
              self.write(', ')
          self.write('))')
  
      def visit_Compare(self, node, frame):
          self.visit(node.expr, frame)
          for op in node.ops:
              self.visit(op, frame)
  
      def visit_Operand(self, node, frame):
          self.write(' %s ' % operators[node.op])
          self.visit(node.expr, frame)
  
      def visit_Getattr(self, node, frame):
          self.write('environment.getattr(')
          self.visit(node.node, frame)
          self.write(', %r)' % node.attr)
  
      def visit_Getitem(self, node, frame):
          # slices bypass the environment getitem method.
          if isinstance(node.arg, nodes.Slice):
              self.visit(node.node, frame)
              self.write('[')
              self.visit(node.arg, frame)
              self.write(']')
          else:
              self.write('environment.getitem(')
              self.visit(node.node, frame)
              self.write(', ')
              self.visit(node.arg, frame)
              self.write(')')
  
      def visit_Slice(self, node, frame):
          if node.start is not None:
              self.visit(node.start, frame)
          self.write(':')
          if node.stop is not None:
              self.visit(node.stop, frame)
          if node.step is not None:
              self.write(':')
              self.visit(node.step, frame)
  
      def visit_Filter(self, node, frame):
          self.write(self.filters[node.name] + '(')
          func = self.environment.filters.get(node.name)
          if func is None:
              self.fail('no filter named %r' % node.name, node.lineno)
          if getattr(func, 'contextfilter', False):
              self.write('context, ')
          elif getattr(func, 'evalcontextfilter', False):
              self.write('context.eval_ctx, ')
          elif getattr(func, 'environmentfilter', False):
              self.write('environment, ')
  
          # if the filter node is None we are inside a filter block
          # and want to write to the current buffer
          if node.node is not None:
              self.visit(node.node, frame)
          elif frame.eval_ctx.volatile:
              self.write('(context.eval_ctx.autoescape and'
                         ' Markup(concat(%s)) or concat(%s))' %
                         (frame.buffer, frame.buffer))
          elif frame.eval_ctx.autoescape:
              self.write('Markup(concat(%s))' % frame.buffer)
          else:
              self.write('concat(%s)' % frame.buffer)
          self.signature(node, frame)
          self.write(')')
  
      def visit_Test(self, node, frame):
          self.write(self.tests[node.name] + '(')
          if node.name not in self.environment.tests:
              self.fail('no test named %r' % node.name, node.lineno)
          self.visit(node.node, frame)
          self.signature(node, frame)
          self.write(')')
  
      def visit_CondExpr(self, node, frame):
          def write_expr2():
              if node.expr2 is not None:
                  return self.visit(node.expr2, frame)
              self.write('environment.undefined(%r)' % ('the inline if-'
                         'expression on %s evaluated to false and '
                         'no else section was defined.' % self.position(node)))
  
          if not have_condexpr:
              self.write('((')
              self.visit(node.test, frame)
              self.write(') and (')
              self.visit(node.expr1, frame)
              self.write(',) or (')
              write_expr2()
              self.write(',))[0]')
          else:
              self.write('(')
              self.visit(node.expr1, frame)
              self.write(' if ')
              self.visit(node.test, frame)
              self.write(' else ')
              write_expr2()
              self.write(')')
  
      def visit_Call(self, node, frame, forward_caller=False):
          if self.environment.sandboxed:
              self.write('environment.call(context, ')
          else:
              self.write('context.call(')
          self.visit(node.node, frame)
          extra_kwargs = forward_caller and {'caller': 'caller'} or None
          self.signature(node, frame, extra_kwargs)
          self.write(')')
  
      def visit_Keyword(self, node, frame):
          self.write(node.key + '=')
          self.visit(node.value, frame)
  
      # -- Unused nodes for extensions
  
      def visit_MarkSafe(self, node, frame):
          self.write('Markup(')
          self.visit(node.expr, frame)
          self.write(')')
  
      def visit_MarkSafeIfAutoescape(self, node, frame):
          self.write('(context.eval_ctx.autoescape and Markup or identity)(')
          self.visit(node.expr, frame)
          self.write(')')
  
      def visit_EnvironmentAttribute(self, node, frame):
          self.write('environment.' + node.name)
  
      def visit_ExtensionAttribute(self, node, frame):
          self.write('environment.extensions[%r].%s' % (node.identifier, node.name))
  
      def visit_ImportedName(self, node, frame):
          self.write(self.import_aliases[node.importname])
  
      def visit_InternalName(self, node, frame):
          self.write(node.name)
  
      def visit_ContextReference(self, node, frame):
          self.write('context')
  
      def visit_Continue(self, node, frame):
          self.writeline('continue', node)
  
      def visit_Break(self, node, frame):
          self.writeline('break', node)
  
      def visit_Scope(self, node, frame):
          scope_frame = frame.inner()
          scope_frame.inspect(node.iter_child_nodes())
          aliases = self.push_scope(scope_frame)
          self.pull_locals(scope_frame)
          self.blockvisit(node.body, scope_frame)
          self.pop_scope(aliases, scope_frame)
  
      def visit_EvalContextModifier(self, node, frame):
          for keyword in node.options:
              self.writeline('context.eval_ctx.%s = ' % keyword.key)
              self.visit(keyword.value, frame)
              try:
                  val = keyword.value.as_const(frame.eval_ctx)
              except nodes.Impossible:
                  frame.eval_ctx.volatile = True
              else:
                  setattr(frame.eval_ctx, keyword.key, val)
  
      def visit_ScopedEvalContextModifier(self, node, frame):
          old_ctx_name = self.temporary_identifier()
          safed_ctx = frame.eval_ctx.save()
          self.writeline('%s = context.eval_ctx.save()' % old_ctx_name)
          self.visit_EvalContextModifier(node, frame)
          for child in node.body:
              self.visit(child, frame)
          frame.eval_ctx.revert(safed_ctx)
          self.writeline('context.eval_ctx.revert(%s)' % old_ctx_name)
  