text: # -*- coding: utf-8 -*-
  """
      jinja2.ext
      ~~~~~~~~~~
  
      Jinja extensions allow to add custom tags similar to the way django custom
      tags work.  By default two example extensions exist: an i18n and a cache
      extension.
  
      :copyright: (c) 2010 by the Jinja Team.
      :license: BSD.
  """
  from jinja2 import nodes
  from jinja2.defaults import BLOCK_START_STRING, \
       BLOCK_END_STRING, VARIABLE_START_STRING, VARIABLE_END_STRING, \
       COMMENT_START_STRING, COMMENT_END_STRING, LINE_STATEMENT_PREFIX, \
       LINE_COMMENT_PREFIX, TRIM_BLOCKS, NEWLINE_SEQUENCE, \
       KEEP_TRAILING_NEWLINE, LSTRIP_BLOCKS
  from jinja2.environment import Environment
  from jinja2.runtime import concat
  from jinja2.exceptions import TemplateAssertionError, TemplateSyntaxError
  from jinja2.utils import contextfunction, import_string, Markup
  from jinja2._compat import with_metaclass, string_types, iteritems
  
  
  # the only real useful gettext functions for a Jinja template.  Note
  # that ugettext must be assigned to gettext as Jinja doesn't support
  # non unicode strings.
  GETTEXT_FUNCTIONS = ('_', 'gettext', 'ngettext')
  
  
  class ExtensionRegistry(type):
      """Gives the extension an unique identifier."""
  
      def __new__(cls, name, bases, d):
          rv = type.__new__(cls, name, bases, d)
          rv.identifier = rv.__module__ + '.' + rv.__name__
          return rv
  
  
  class Extension(with_metaclass(ExtensionRegistry, object)):
      """Extensions can be used to add extra functionality to the Jinja template
      system at the parser level.  Custom extensions are bound to an environment
      but may not store environment specific data on `self`.  The reason for
      this is that an extension can be bound to another environment (for
      overlays) by creating a copy and reassigning the `environment` attribute.
  
      As extensions are created by the environment they cannot accept any
      arguments for configuration.  One may want to work around that by using
      a factory function, but that is not possible as extensions are identified
      by their import name.  The correct way to configure the extension is
      storing the configuration values on the environment.  Because this way the
      environment ends up acting as central configuration storage the
      attributes may clash which is why extensions have to ensure that the names
      they choose for configuration are not too generic.  ``prefix`` for example
      is a terrible name, ``fragment_cache_prefix`` on the other hand is a good
      name as includes the name of the extension (fragment cache).
      """
  
      #: if this extension parses this is the list of tags it's listening to.
      tags = set()
  
      #: the priority of that extension.  This is especially useful for
      #: extensions that preprocess values.  A lower value means higher
      #: priority.
      #:
      #: .. versionadded:: 2.4
      priority = 100
  
      def __init__(self, environment):
          self.environment = environment
  
      def bind(self, environment):
          """Create a copy of this extension bound to another environment."""
          rv = object.__new__(self.__class__)
          rv.__dict__.update(self.__dict__)
          rv.environment = environment
          return rv
  
      def preprocess(self, source, name, filename=None):
          """This method is called before the actual lexing and can be used to
          preprocess the source.  The `filename` is optional.  The return value
          must be the preprocessed source.
          """
          return source
  
      def filter_stream(self, stream):
          """It's passed a :class:`~jinja2.lexer.TokenStream` that can be used
          to filter tokens returned.  This method has to return an iterable of
          :class:`~jinja2.lexer.Token`\s, but it doesn't have to return a
          :class:`~jinja2.lexer.TokenStream`.
  
          In the `ext` folder of the Jinja2 source distribution there is a file
          called `inlinegettext.py` which implements a filter that utilizes this
          method.
          """
          return stream
  
      def parse(self, parser):
          """If any of the :attr:`tags` matched this method is called with the
          parser as first argument.  The token the parser stream is pointing at
          is the name token that matched.  This method has to return one or a
          list of multiple nodes.
          """
          raise NotImplementedError()
  
      def attr(self, name, lineno=None):
          """Return an attribute node for the current extension.  This is useful
          to pass constants on extensions to generated template code.
  
          ::
  
              self.attr('_my_attribute', lineno=lineno)
          """
          return nodes.ExtensionAttribute(self.identifier, name, lineno=lineno)
  
      def call_method(self, name, args=None, kwargs=None, dyn_args=None,
                      dyn_kwargs=None, lineno=None):
          """Call a method of the extension.  This is a shortcut for
          :meth:`attr` + :class:`jinja2.nodes.Call`.
          """
          if args is None:
              args = []
          if kwargs is None:
              kwargs = []
          return nodes.Call(self.attr(name, lineno=lineno), args, kwargs,
                            dyn_args, dyn_kwargs, lineno=lineno)
  
  
  @contextfunction
  def _gettext_alias(__context, *args, **kwargs):
      return __context.call(__context.resolve('gettext'), *args, **kwargs)
  
  
  def _make_new_gettext(func):
      @contextfunction
      def gettext(__context, __string, **variables):
          rv = __context.call(func, __string)
          if __context.eval_ctx.autoescape:
              rv = Markup(rv)
          return rv % variables
      return gettext
  
  
  def _make_new_ngettext(func):
      @contextfunction
      def ngettext(__context, __singular, __plural, __num, **variables):
          variables.setdefault('num', __num)
          rv = __context.call(func, __singular, __plural, __num)
          if __context.eval_ctx.autoescape:
              rv = Markup(rv)
          return rv % variables
      return ngettext
  
  
  class InternationalizationExtension(Extension):
      """This extension adds gettext support to Jinja2."""
      tags = set(['trans'])
  
      # TODO: the i18n extension is currently reevaluating values in a few
      # situations.  Take this example:
      #   {% trans count=something() %}{{ count }} foo{% pluralize
      #     %}{{ count }} fooss{% endtrans %}
      # something is called twice here.  One time for the gettext value and
      # the other time for the n-parameter of the ngettext function.
  
      def __init__(self, environment):
          Extension.__init__(self, environment)
          environment.globals['_'] = _gettext_alias
          environment.extend(
              install_gettext_translations=self._install,
              install_null_translations=self._install_null,
              install_gettext_callables=self._install_callables,
              uninstall_gettext_translations=self._uninstall,
              extract_translations=self._extract,
              newstyle_gettext=False
          )
  
      def _install(self, translations, newstyle=None):
          gettext = getattr(translations, 'ugettext', None)
          if gettext is None:
              gettext = translations.gettext
          ngettext = getattr(translations, 'ungettext', None)
          if ngettext is None:
              ngettext = translations.ngettext
          self._install_callables(gettext, ngettext, newstyle)
  
      def _install_null(self, newstyle=None):
          self._install_callables(
              lambda x: x,
              lambda s, p, n: (n != 1 and (p,) or (s,))[0],
              newstyle
          )
  
      def _install_callables(self, gettext, ngettext, newstyle=None):
          if newstyle is not None:
              self.environment.newstyle_gettext = newstyle
          if self.environment.newstyle_gettext:
              gettext = _make_new_gettext(gettext)
              ngettext = _make_new_ngettext(ngettext)
          self.environment.globals.update(
              gettext=gettext,
              ngettext=ngettext
          )
  
      def _uninstall(self, translations):
          for key in 'gettext', 'ngettext':
              self.environment.globals.pop(key, None)
  
      def _extract(self, source, gettext_functions=GETTEXT_FUNCTIONS):
          if isinstance(source, string_types):
              source = self.environment.parse(source)
          return extract_from_ast(source, gettext_functions)
  
      def parse(self, parser):
          """Parse a translatable tag."""
          lineno = next(parser.stream).lineno
          num_called_num = False
  
          # find all the variables referenced.  Additionally a variable can be
          # defined in the body of the trans block too, but this is checked at
          # a later state.
          plural_expr = None
          plural_expr_assignment = None
          variables = {}
          while parser.stream.current.type != 'block_end':
              if variables:
                  parser.stream.expect('comma')
  
              # skip colon for python compatibility
              if parser.stream.skip_if('colon'):
                  break
  
              name = parser.stream.expect('name')
              if name.value in variables:
                  parser.fail('translatable variable %r defined twice.' %
                              name.value, name.lineno,
                              exc=TemplateAssertionError)
  
              # expressions
              if parser.stream.current.type == 'assign':
                  next(parser.stream)
                  variables[name.value] = var = parser.parse_expression()
              else:
                  variables[name.value] = var = nodes.Name(name.value, 'load')
  
              if plural_expr is None:
                  if isinstance(var, nodes.Call):
                      plural_expr = nodes.Name('_trans', 'load')
                      variables[name.value] = plural_expr
                      plural_expr_assignment = nodes.Assign(
                          nodes.Name('_trans', 'store'), var)
                  else:
                      plural_expr = var
                  num_called_num = name.value == 'num'
  
          parser.stream.expect('block_end')
  
          plural = plural_names = None
          have_plural = False
          referenced = set()
  
          # now parse until endtrans or pluralize
          singular_names, singular = self._parse_block(parser, True)
          if singular_names:
              referenced.update(singular_names)
              if plural_expr is None:
                  plural_expr = nodes.Name(singular_names[0], 'load')
                  num_called_num = singular_names[0] == 'num'
  
          # if we have a pluralize block, we parse that too
          if parser.stream.current.test('name:pluralize'):
              have_plural = True
              next(parser.stream)
              if parser.stream.current.type != 'block_end':
                  name = parser.stream.expect('name')
                  if name.value not in variables:
                      parser.fail('unknown variable %r for pluralization' %
                                  name.value, name.lineno,
                                  exc=TemplateAssertionError)
                  plural_expr = variables[name.value]
                  num_called_num = name.value == 'num'
              parser.stream.expect('block_end')
              plural_names, plural = self._parse_block(parser, False)
              next(parser.stream)
              referenced.update(plural_names)
          else:
              next(parser.stream)
  
          # register free names as simple name expressions
          for var in referenced:
              if var not in variables:
                  variables[var] = nodes.Name(var, 'load')
  
          if not have_plural:
              plural_expr = None
          elif plural_expr is None:
              parser.fail('pluralize without variables', lineno)
  
          node = self._make_node(singular, plural, variables, plural_expr,
                                 bool(referenced),
                                 num_called_num and have_plural)
          node.set_lineno(lineno)
          if plural_expr_assignment is not None:
              return [plural_expr_assignment, node]
          else:
              return node
  
      def _parse_block(self, parser, allow_pluralize):
          """Parse until the next block tag with a given name."""
          referenced = []
          buf = []
          while 1:
              if parser.stream.current.type == 'data':
                  buf.append(parser.stream.current.value.replace('%', '%%'))
                  next(parser.stream)
              elif parser.stream.current.type == 'variable_begin':
                  next(parser.stream)
                  name = parser.stream.expect('name').value
                  referenced.append(name)
                  buf.append('%%(%s)s' % name)
                  parser.stream.expect('variable_end')
              elif parser.stream.current.type == 'block_begin':
                  next(parser.stream)
                  if parser.stream.current.test('name:endtrans'):
                      break
                  elif parser.stream.current.test('name:pluralize'):
                      if allow_pluralize:
                          break
                      parser.fail('a translatable section can have only one '
                                  'pluralize section')
                  parser.fail('control structures in translatable sections are '
                              'not allowed')
              elif parser.stream.eos:
                  parser.fail('unclosed translation block')
              else:
                  assert False, 'internal parser error'
  
          return referenced, concat(buf)
  
      def _make_node(self, singular, plural, variables, plural_expr,
                     vars_referenced, num_called_num):
          """Generates a useful node from the data provided."""
          # no variables referenced?  no need to escape for old style
          # gettext invocations only if there are vars.
          if not vars_referenced and not self.environment.newstyle_gettext:
              singular = singular.replace('%%', '%')
              if plural:
                  plural = plural.replace('%%', '%')
  
          # singular only:
          if plural_expr is None:
              gettext = nodes.Name('gettext', 'load')
              node = nodes.Call(gettext, [nodes.Const(singular)],
                                [], None, None)
  
          # singular and plural
          else:
              ngettext = nodes.Name('ngettext', 'load')
              node = nodes.Call(ngettext, [
                  nodes.Const(singular),
                  nodes.Const(plural),
                  plural_expr
              ], [], None, None)
  
          # in case newstyle gettext is used, the method is powerful
          # enough to handle the variable expansion and autoescape
          # handling itself
          if self.environment.newstyle_gettext:
              for key, value in iteritems(variables):
                  # the function adds that later anyways in case num was
                  # called num, so just skip it.
                  if num_called_num and key == 'num':
                      continue
                  node.kwargs.append(nodes.Keyword(key, value))
  
          # otherwise do that here
          else:
              # mark the return value as safe if we are in an
              # environment with autoescaping turned on
              node = nodes.MarkSafeIfAutoescape(node)
              if variables:
                  node = nodes.Mod(node, nodes.Dict([
                      nodes.Pair(nodes.Const(key), value)
                      for key, value in variables.items()
                  ]))
          return nodes.Output([node])
  
  
  class ExprStmtExtension(Extension):
      """Adds a `do` tag to Jinja2 that works like the print statement just
      that it doesn't print the return value.
      """
      tags = set(['do'])
  
      def parse(self, parser):
          node = nodes.ExprStmt(lineno=next(parser.stream).lineno)
          node.node = parser.parse_tuple()
          return node
  
  
  class LoopControlExtension(Extension):
      """Adds break and continue to the template engine."""
      tags = set(['break', 'continue'])
  
      def parse(self, parser):
          token = next(parser.stream)
          if token.value == 'break':
              return nodes.Break(lineno=token.lineno)
          return nodes.Continue(lineno=token.lineno)
  
  
  class WithExtension(Extension):
      """Adds support for a django-like with block."""
      tags = set(['with'])
  
      def parse(self, parser):
          node = nodes.Scope(lineno=next(parser.stream).lineno)
          assignments = []
          while parser.stream.current.type != 'block_end':
              lineno = parser.stream.current.lineno
              if assignments:
                  parser.stream.expect('comma')
              target = parser.parse_assign_target()
              parser.stream.expect('assign')
              expr = parser.parse_expression()
              assignments.append(nodes.Assign(target, expr, lineno=lineno))
          node.body = assignments + \
              list(parser.parse_statements(('name:endwith',),
                                           drop_needle=True))
          return node
  
  
  class AutoEscapeExtension(Extension):
      """Changes auto escape rules for a scope."""
      tags = set(['autoescape'])
  
      def parse(self, parser):
          node = nodes.ScopedEvalContextModifier(lineno=next(parser.stream).lineno)
          node.options = [
              nodes.Keyword('autoescape', parser.parse_expression())
          ]
          node.body = parser.parse_statements(('name:endautoescape',),
                                              drop_needle=True)
          return nodes.Scope([node])
  
  
  def extract_from_ast(node, gettext_functions=GETTEXT_FUNCTIONS,
                       babel_style=True):
      """Extract localizable strings from the given template node.  Per
      default this function returns matches in babel style that means non string
      parameters as well as keyword arguments are returned as `None`.  This
      allows Babel to figure out what you really meant if you are using
      gettext functions that allow keyword arguments for placeholder expansion.
      If you don't want that behavior set the `babel_style` parameter to `False`
      which causes only strings to be returned and parameters are always stored
      in tuples.  As a consequence invalid gettext calls (calls without a single
      string parameter or string parameters after non-string parameters) are
      skipped.
  
      This example explains the behavior:
  
      >>> from jinja2 import Environment
      >>> env = Environment()
      >>> node = env.parse('{{ (_("foo"), _(), ngettext("foo", "bar", 42)) }}')
      >>> list(extract_from_ast(node))
      [(1, '_', 'foo'), (1, '_', ()), (1, 'ngettext', ('foo', 'bar', None))]
      >>> list(extract_from_ast(node, babel_style=False))
      [(1, '_', ('foo',)), (1, 'ngettext', ('foo', 'bar'))]
  
      For every string found this function yields a ``(lineno, function,
      message)`` tuple, where:
  
      * ``lineno`` is the number of the line on which the string was found,
      * ``function`` is the name of the ``gettext`` function used (if the
        string was extracted from embedded Python code), and
      *  ``message`` is the string itself (a ``unicode`` object, or a tuple
         of ``unicode`` objects for functions with multiple string arguments).
  
      This extraction function operates on the AST and is because of that unable
      to extract any comments.  For comment support you have to use the babel
      extraction interface or extract comments yourself.
      """
      for node in node.find_all(nodes.Call):
          if not isinstance(node.node, nodes.Name) or \
             node.node.name not in gettext_functions:
              continue
  
          strings = []
          for arg in node.args:
              if isinstance(arg, nodes.Const) and \
                 isinstance(arg.value, string_types):
                  strings.append(arg.value)
              else:
                  strings.append(None)
  
          for arg in node.kwargs:
              strings.append(None)
          if node.dyn_args is not None:
              strings.append(None)
          if node.dyn_kwargs is not None:
              strings.append(None)
  
          if not babel_style:
              strings = tuple(x for x in strings if x is not None)
              if not strings:
                  continue
          else:
              if len(strings) == 1:
                  strings = strings[0]
              else:
                  strings = tuple(strings)
          yield node.lineno, node.node.name, strings
  
  
  class _CommentFinder(object):
      """Helper class to find comments in a token stream.  Can only
      find comments for gettext calls forwards.  Once the comment
      from line 4 is found, a comment for line 1 will not return a
      usable value.
      """
  
      def __init__(self, tokens, comment_tags):
          self.tokens = tokens
          self.comment_tags = comment_tags
          self.offset = 0
          self.last_lineno = 0
  
      def find_backwards(self, offset):
          try:
              for _, token_type, token_value in \
                      reversed(self.tokens[self.offset:offset]):
                  if token_type in ('comment', 'linecomment'):
                      try:
                          prefix, comment = token_value.split(None, 1)
                      except ValueError:
                          continue
                      if prefix in self.comment_tags:
                          return [comment.rstrip()]
              return []
          finally:
              self.offset = offset
  
      def find_comments(self, lineno):
          if not self.comment_tags or self.last_lineno > lineno:
              return []
          for idx, (token_lineno, _, _) in enumerate(self.tokens[self.offset:]):
              if token_lineno > lineno:
                  return self.find_backwards(self.offset + idx)
          return self.find_backwards(len(self.tokens))
  
  
  def babel_extract(fileobj, keywords, comment_tags, options):
      """Babel extraction method for Jinja templates.
  
      .. versionchanged:: 2.3
         Basic support for translation comments was added.  If `comment_tags`
         is now set to a list of keywords for extraction, the extractor will
         try to find the best preceeding comment that begins with one of the
         keywords.  For best results, make sure to not have more than one
         gettext call in one line of code and the matching comment in the
         same line or the line before.
  
      .. versionchanged:: 2.5.1
         The `newstyle_gettext` flag can be set to `True` to enable newstyle
         gettext calls.
  
      .. versionchanged:: 2.7
         A `silent` option can now be provided.  If set to `False` template
         syntax errors are propagated instead of being ignored.
  
      :param fileobj: the file-like object the messages should be extracted from
      :param keywords: a list of keywords (i.e. function names) that should be
                       recognized as translation functions
      :param comment_tags: a list of translator tags to search for and include
                           in the results.
      :param options: a dictionary of additional options (optional)
      :return: an iterator over ``(lineno, funcname, message, comments)`` tuples.
               (comments will be empty currently)
      """
      extensions = set()
      for extension in options.get('extensions', '').split(','):
          extension = extension.strip()
          if not extension:
              continue
          extensions.add(import_string(extension))
      if InternationalizationExtension not in extensions:
          extensions.add(InternationalizationExtension)
  
      def getbool(options, key, default=False):
          return options.get(key, str(default)).lower() in \
              ('1', 'on', 'yes', 'true')
  
      silent = getbool(options, 'silent', True)
      environment = Environment(
          options.get('block_start_string', BLOCK_START_STRING),
          options.get('block_end_string', BLOCK_END_STRING),
          options.get('variable_start_string', VARIABLE_START_STRING),
          options.get('variable_end_string', VARIABLE_END_STRING),
          options.get('comment_start_string', COMMENT_START_STRING),
          options.get('comment_end_string', COMMENT_END_STRING),
          options.get('line_statement_prefix') or LINE_STATEMENT_PREFIX,
          options.get('line_comment_prefix') or LINE_COMMENT_PREFIX,
          getbool(options, 'trim_blocks', TRIM_BLOCKS),
          getbool(options, 'lstrip_blocks', LSTRIP_BLOCKS),
          NEWLINE_SEQUENCE,
          getbool(options, 'keep_trailing_newline', KEEP_TRAILING_NEWLINE),
          frozenset(extensions),
          cache_size=0,
          auto_reload=False
      )
  
      if getbool(options, 'newstyle_gettext'):
          environment.newstyle_gettext = True
  
      source = fileobj.read().decode(options.get('encoding', 'utf-8'))
      try:
          node = environment.parse(source)
          tokens = list(environment.lex(environment.preprocess(source)))
      except TemplateSyntaxError as e:
          if not silent:
              raise
          # skip templates with syntax errors
          return
  
      finder = _CommentFinder(tokens, comment_tags)
      for lineno, func, message in extract_from_ast(node, keywords):
          yield lineno, func, message, finder.find_comments(lineno)
  
  
  #: nicer import names
  i18n = InternationalizationExtension
  do = ExprStmtExtension
  loopcontrols = LoopControlExtension
  with_ = WithExtension
  autoescape = AutoEscapeExtension
  