text: # -*- coding: utf-8 -*-
  """
      jinja2.runtime
      ~~~~~~~~~~~~~~
  
      Runtime helpers.
  
      :copyright: Copyright 2008 by Armin Ronacher.
      :license: BSD.
  """
  import sys
  from itertools import chain, imap
  from jinja2.utils import Markup, partial, soft_unicode, escape, missing, \
       concat, MethodType, FunctionType
  from jinja2.exceptions import UndefinedError, TemplateRuntimeError
  
  
  # these variables are exported to the template runtime
  __all__ = ['LoopContext', 'Context', 'TemplateReference', 'Macro', 'Markup',
             'TemplateRuntimeError', 'missing', 'concat', 'escape',
             'markup_join', 'unicode_join']
  
  
  #: the types we support for context functions
  _context_function_types = (FunctionType, MethodType)
  
  
  def markup_join(seq):
      """Concatenation that escapes if necessary and converts to unicode."""
      buf = []
      iterator = imap(soft_unicode, seq)
      for arg in iterator:
          buf.append(arg)
          if hasattr(arg, '__html__'):
              return Markup(u'').join(chain(buf, iterator))
      return concat(buf)
  
  
  def unicode_join(seq):
      """Simple args to unicode conversion and concatenation."""
      return concat(imap(unicode, seq))
  
  
  class Context(object):
      """The template context holds the variables of a template.  It stores the
      values passed to the template and also the names the template exports.
      Creating instances is neither supported nor useful as it's created
      automatically at various stages of the template evaluation and should not
      be created by hand.
  
      The context is immutable.  Modifications on :attr:`parent` **must not**
      happen and modifications on :attr:`vars` are allowed from generated
      template code only.  Template filters and global functions marked as
      :func:`contextfunction`\s get the active context passed as first argument
      and are allowed to access the context read-only.
  
      The template context supports read only dict operations (`get`,
      `keys`, `values`, `items`, `iterkeys`, `itervalues`, `iteritems`,
      `__getitem__`, `__contains__`).  Additionally there is a :meth:`resolve`
      method that doesn't fail with a `KeyError` but returns an
      :class:`Undefined` object for missing variables.
      """
      __slots__ = ('parent', 'vars', 'environment', 'exported_vars', 'name',
                   'blocks', '__weakref__')
  
      def __init__(self, environment, parent, name, blocks):
          self.parent = parent
          self.vars = vars = {}
          self.environment = environment
          self.exported_vars = set()
          self.name = name
  
          # create the initial mapping of blocks.  Whenever template inheritance
          # takes place the runtime will update this mapping with the new blocks
          # from the template.
          self.blocks = dict((k, [v]) for k, v in blocks.iteritems())
  
      def super(self, name, current):
          """Render a parent block."""
          try:
              blocks = self.blocks[name]
              index = blocks.index(current) + 1
              blocks[index]
          except LookupError:
              return self.environment.undefined('there is no parent block '
                                                'called %r.' % name,
                                                name='super')
          return BlockReference(name, self, blocks, index)
  
      def get(self, key, default=None):
          """Returns an item from the template context, if it doesn't exist
          `default` is returned.
          """
          try:
              return self[key]
          except KeyError:
              return default
  
      def resolve(self, key):
          """Looks up a variable like `__getitem__` or `get` but returns an
          :class:`Undefined` object with the name of the name looked up.
          """
          if key in self.vars:
              return self.vars[key]
          if key in self.parent:
              return self.parent[key]
          return self.environment.undefined(name=key)
  
      def get_exported(self):
          """Get a new dict with the exported variables."""
          return dict((k, self.vars[k]) for k in self.exported_vars)
  
      def get_all(self):
          """Return a copy of the complete context as dict including the
          exported variables.
          """
          return dict(self.parent, **self.vars)
  
      def call(__self, __obj, *args, **kwargs):
          """Call the callable with the arguments and keyword arguments
          provided but inject the active context or environment as first
          argument if the callable is a :func:`contextfunction` or
          :func:`environmentfunction`.
          """
          if __debug__:
              __traceback_hide__ = True
          if isinstance(__obj, _context_function_types):
              if getattr(__obj, 'contextfunction', 0):
                  args = (__self,) + args
              elif getattr(__obj, 'environmentfunction', 0):
                  args = (__self.environment,) + args
          return __obj(*args, **kwargs)
  
      def _all(meth):
          proxy = lambda self: getattr(self.get_all(), meth)()
          proxy.__doc__ = getattr(dict, meth).__doc__
          proxy.__name__ = meth
          return proxy
  
      keys = _all('keys')
      values = _all('values')
      items = _all('items')
      iterkeys = _all('iterkeys')
      itervalues = _all('itervalues')
      iteritems = _all('iteritems')
      del _all
  
      def __contains__(self, name):
          return name in self.vars or name in self.parent
  
      def __getitem__(self, key):
          """Lookup a variable or raise `KeyError` if the variable is
          undefined.
          """
          item = self.resolve(key)
          if isinstance(item, Undefined):
              raise KeyError(key)
          return item
  
      def __repr__(self):
          return '<%s %s of %r>' % (
              self.__class__.__name__,
              repr(self.get_all()),
              self.name
          )
  
  
  # register the context as mapping if possible
  try:
      from collections import Mapping
      Mapping.register(Context)
  except ImportError:
      pass
  
  
  class TemplateReference(object):
      """The `self` in templates."""
  
      def __init__(self, context):
          self.__context = context
  
      def __getitem__(self, name):
          blocks = self.__context.blocks[name]
          wrap = self.__context.environment.autoescape and \
                 Markup or (lambda x: x)
          return BlockReference(name, self.__context, blocks, 0)
  
      def __repr__(self):
          return '<%s %r>' % (
              self.__class__.__name__,
              self.__context.name
          )
  
  
  class BlockReference(object):
      """One block on a template reference."""
  
      def __init__(self, name, context, stack, depth):
          self.name = name
          self._context = context
          self._stack = stack
          self._depth = depth
  
      @property
      def super(self):
          """Super the block."""
          if self._depth + 1 >= len(self._stack):
              return self._context.environment. \
                  undefined('there is no parent block called %r.' %
                            self.name, name='super')
          return BlockReference(self.name, self._context, self._stack,
                                self._depth + 1)
  
      def __call__(self):
          rv = concat(self._stack[self._depth](self._context))
          if self._context.environment.autoescape:
              rv = Markup(rv)
          return rv
  
  
  class LoopContext(object):
      """A loop context for dynamic iteration."""
  
      def __init__(self, iterable, recurse=None):
          self._iterator = iter(iterable)
          self._recurse = recurse
          self.index0 = -1
  
          # try to get the length of the iterable early.  This must be done
          # here because there are some broken iterators around where there
          # __len__ is the number of iterations left (i'm looking at your
          # listreverseiterator!).
          try:
              self._length = len(iterable)
          except (TypeError, AttributeError):
              self._length = None
  
      def cycle(self, *args):
          """Cycles among the arguments with the current loop index."""
          if not args:
              raise TypeError('no items for cycling given')
          return args[self.index0 % len(args)]
  
      first = property(lambda x: x.index0 == 0)
      last = property(lambda x: x.index0 + 1 == x.length)
      index = property(lambda x: x.index0 + 1)
      revindex = property(lambda x: x.length - x.index0)
      revindex0 = property(lambda x: x.length - x.index)
  
      def __len__(self):
          return self.length
  
      def __iter__(self):
          return LoopContextIterator(self)
  
      def loop(self, iterable):
          if self._recurse is None:
              raise TypeError('Tried to call non recursive loop.  Maybe you '
                              "forgot the 'recursive' modifier.")
          return self._recurse(iterable, self._recurse)
  
      # a nifty trick to enhance the error message if someone tried to call
      # the the loop without or with too many arguments.
      __call__ = loop; del loop
  
      @property
      def length(self):
          if self._length is None:
              # if was not possible to get the length of the iterator when
              # the loop context was created (ie: iterating over a generator)
              # we have to convert the iterable into a sequence and use the
              # length of that.
              iterable = tuple(self._iterator)
              self._iterator = iter(iterable)
              self._length = len(iterable) + self.index0 + 1
          return self._length
  
      def __repr__(self):
          return '<%s %r/%r>' % (
              self.__class__.__name__,
              self.index,
              self.length
          )
  
  
  class LoopContextIterator(object):
      """The iterator for a loop context."""
      __slots__ = ('context',)
  
      def __init__(self, context):
          self.context = context
  
      def __iter__(self):
          return self
  
      def next(self):
          ctx = self.context
          ctx.index0 += 1
          return ctx._iterator.next(), ctx
  
  
  class Macro(object):
      """Wraps a macro."""
  
      def __init__(self, environment, func, name, arguments, defaults,
                   catch_kwargs, catch_varargs, caller):
          self._environment = environment
          self._func = func
          self._argument_count = len(arguments)
          self.name = name
          self.arguments = arguments
          self.defaults = defaults
          self.catch_kwargs = catch_kwargs
          self.catch_varargs = catch_varargs
          self.caller = caller
  
      def __call__(self, *args, **kwargs):
          arguments = []
          for idx, name in enumerate(self.arguments):
              try:
                  value = args[idx]
              except:
                  try:
                      value = kwargs.pop(name)
                  except:
                      try:
                          value = self.defaults[idx - self._argument_count]
                      except:
                          value = self._environment.undefined(
                              'parameter %r was not provided' % name, name=name)
              arguments.append(value)
  
          # it's important that the order of these arguments does not change
          # if not also changed in the compiler's `function_scoping` method.
          # the order is caller, keyword arguments, positional arguments!
          if self.caller:
              caller = kwargs.pop('caller', None)
              if caller is None:
                  caller = self._environment.undefined('No caller defined',
                                                       name='caller')
              arguments.append(caller)
          if self.catch_kwargs:
              arguments.append(kwargs)
          elif kwargs:
              raise TypeError('macro %r takes no keyword argument %r' %
                              (self.name, iter(kwargs).next()))
          if self.catch_varargs:
              arguments.append(args[self._argument_count:])
          elif len(args) > self._argument_count:
              raise TypeError('macro %r takes not more than %d argument(s)' %
                              (self.name, len(self.arguments)))
          return self._func(*arguments)
  
      def __repr__(self):
          return '<%s %s>' % (
              self.__class__.__name__,
              self.name is None and 'anonymous' or repr(self.name)
          )
  
  
  class Undefined(object):
      """The default undefined type.  This undefined type can be printed and
      iterated over, but every other access will raise an :exc:`UndefinedError`:
  
      >>> foo = Undefined(name='foo')
      >>> str(foo)
      ''
      >>> not foo
      True
      >>> foo + 42
      Traceback (most recent call last):
        ...
      UndefinedError: 'foo' is undefined
      """
      __slots__ = ('_undefined_hint', '_undefined_obj', '_undefined_name',
                   '_undefined_exception')
  
      def __init__(self, hint=None, obj=None, name=None, exc=UndefinedError):
          self._undefined_hint = hint
          self._undefined_obj = obj
          self._undefined_name = name
          self._undefined_exception = exc
  
      def _fail_with_undefined_error(self, *args, **kwargs):
          """Regular callback function for undefined objects that raises an
          `UndefinedError` on call.
          """
          if self._undefined_hint is None:
              if self._undefined_obj is None:
                  hint = '%r is undefined' % self._undefined_name
              elif not isinstance(self._undefined_name, basestring):
                  hint = '%r object has no element %r' % (
                      self._undefined_obj.__class__.__name__,
                      self._undefined_name
                  )
              else:
                  hint = '%r object has no attribute %r' % (
                      self._undefined_obj.__class__.__name__,
                      self._undefined_name
                  )
          else:
              hint = self._undefined_hint
          raise self._undefined_exception(hint)
  
      __add__ = __radd__ = __mul__ = __rmul__ = __div__ = __rdiv__ = \
      __truediv__ = __rtruediv__ = __floordiv__ = __rfloordiv__ = \
      __mod__ = __rmod__ = __pos__ = __neg__ = __call__ = \
      __getattr__ = __getitem__ = __lt__ = __le__ = __gt__ = __ge__ = \
      __int__ = __float__ = __complex__ = __pow__ = __rpow__ = \
          _fail_with_undefined_error
  
      def __str__(self):
          return unicode(self).encode('utf-8')
  
      def __unicode__(self):
          return u''
  
      def __len__(self):
          return 0
  
      def __iter__(self):
          if 0:
              yield None
  
      def __nonzero__(self):
          return False
  
      def __repr__(self):
          return 'Undefined'
  
  
  class DebugUndefined(Undefined):
      """An undefined that returns the debug info when printed.
  
      >>> foo = DebugUndefined(name='foo')
      >>> str(foo)
      '{{ foo }}'
      >>> not foo
      True
      >>> foo + 42
      Traceback (most recent call last):
        ...
      UndefinedError: 'foo' is undefined
      """
      __slots__ = ()
  
      def __unicode__(self):
          if self._undefined_hint is None:
              if self._undefined_obj is None:
                  return u'{{ %s }}' % self._undefined_name
              return '{{ no such element: %s[%r] }}' % (
                  self._undefined_obj.__class__.__name__,
                  self._undefined_name
              )
          return u'{{ undefined value printed: %s }}' % self._undefined_hint
  
  
  class StrictUndefined(Undefined):
      """An undefined that barks on print and iteration as well as boolean
      tests and all kinds of comparisons.  In other words: you can do nothing
      with it except checking if it's defined using the `defined` test.
  
      >>> foo = StrictUndefined(name='foo')
      >>> str(foo)
      Traceback (most recent call last):
        ...
      UndefinedError: 'foo' is undefined
      >>> not foo
      Traceback (most recent call last):
        ...
      UndefinedError: 'foo' is undefined
      >>> foo + 42
      Traceback (most recent call last):
        ...
      UndefinedError: 'foo' is undefined
      """
      __slots__ = ()
      __iter__ = __unicode__ = __len__ = __nonzero__ = __eq__ = __ne__ = \
          Undefined._fail_with_undefined_error
  
  
  # remove remaining slots attributes, after the metaclass did the magic they
  # are unneeded and irritating as they contain wrong data for the subclasses.
  del Undefined.__slots__, DebugUndefined.__slots__, StrictUndefined.__slots__
  