text: """Classes for managing templates and their runtime and compile time
  options.
  """
  import os
  import sys
  import weakref
  from functools import partial
  from functools import reduce
  from typing import Any
  
  from markupsafe import Markup
  
  from . import nodes
  from .compiler import CodeGenerator
  from .compiler import generate
  from .defaults import BLOCK_END_STRING
  from .defaults import BLOCK_START_STRING
  from .defaults import COMMENT_END_STRING
  from .defaults import COMMENT_START_STRING
  from .defaults import DEFAULT_FILTERS
  from .defaults import DEFAULT_NAMESPACE
  from .defaults import DEFAULT_POLICIES
  from .defaults import DEFAULT_TESTS
  from .defaults import KEEP_TRAILING_NEWLINE
  from .defaults import LINE_COMMENT_PREFIX
  from .defaults import LINE_STATEMENT_PREFIX
  from .defaults import LSTRIP_BLOCKS
  from .defaults import NEWLINE_SEQUENCE
  from .defaults import TRIM_BLOCKS
  from .defaults import VARIABLE_END_STRING
  from .defaults import VARIABLE_START_STRING
  from .exceptions import TemplateNotFound
  from .exceptions import TemplateRuntimeError
  from .exceptions import TemplatesNotFound
  from .exceptions import TemplateSyntaxError
  from .exceptions import UndefinedError
  from .lexer import get_lexer
  from .lexer import TokenStream
  from .nodes import EvalContext
  from .parser import Parser
  from .runtime import Context
  from .runtime import new_context
  from .runtime import Undefined
  from .utils import concat
  from .utils import consume
  from .utils import have_async_gen
  from .utils import import_string
  from .utils import internalcode
  from .utils import LRUCache
  from .utils import missing
  
  # for direct template usage we have up to ten living environments
  _spontaneous_environments = LRUCache(10)
  
  
  def get_spontaneous_environment(cls, *args):
      """Return a new spontaneous environment. A spontaneous environment
      is used for templates created directly rather than through an
      existing environment.
  
      :param cls: Environment class to create.
      :param args: Positional arguments passed to environment.
      """
      key = (cls, args)
  
      try:
          return _spontaneous_environments[key]
      except KeyError:
          _spontaneous_environments[key] = env = cls(*args)
          env.shared = True
          return env
  
  
  def create_cache(size):
      """Return the cache class for the given size."""
      if size == 0:
          return None
      if size < 0:
          return {}
      return LRUCache(size)
  
  
  def copy_cache(cache):
      """Create an empty copy of the given cache."""
      if cache is None:
          return None
      elif type(cache) is dict:
          return {}
      return LRUCache(cache.capacity)
  
  
  def load_extensions(environment, extensions):
      """Load the extensions from the list and bind it to the environment.
      Returns a dict of instantiated environments.
      """
      result = {}
      for extension in extensions:
          if isinstance(extension, str):
              extension = import_string(extension)
          result[extension.identifier] = extension(environment)
      return result
  
  
  def fail_for_missing_callable(thing, name):
      msg = f"no {thing} named {name!r}"
  
      if isinstance(name, Undefined):
          try:
              name._fail_with_undefined_error()
          except Exception as e:
              msg = f"{msg} ({e}; did you forget to quote the callable name?)"
      raise TemplateRuntimeError(msg)
  
  
  def _environment_sanity_check(environment):
      """Perform a sanity check on the environment."""
      assert issubclass(
          environment.undefined, Undefined
      ), "undefined must be a subclass of undefined because filters depend on it."
      assert (
          environment.block_start_string
          != environment.variable_start_string
          != environment.comment_start_string
      ), "block, variable and comment start strings must be different"
      assert environment.newline_sequence in {
          "\r",
          "\r\n",
          "\n",
      }, "newline_sequence set to unknown line ending string."
      return environment
  
  
  class Environment:
      r"""The core component of Jinja is the `Environment`.  It contains
      important shared variables like configuration, filters, tests,
      globals and others.  Instances of this class may be modified if
      they are not shared and if no template was loaded so far.
      Modifications on environments after the first template was loaded
      will lead to surprising effects and undefined behavior.
  
      Here are the possible initialization parameters:
  
          `block_start_string`
              The string marking the beginning of a block.  Defaults to ``'{%'``.
  
          `block_end_string`
              The string marking the end of a block.  Defaults to ``'%}'``.
  
          `variable_start_string`
              The string marking the beginning of a print statement.
              Defaults to ``'{{'``.
  
          `variable_end_string`
              The string marking the end of a print statement.  Defaults to
              ``'}}'``.
  
          `comment_start_string`
              The string marking the beginning of a comment.  Defaults to ``'{#'``.
  
          `comment_end_string`
              The string marking the end of a comment.  Defaults to ``'#}'``.
  
          `line_statement_prefix`
              If given and a string, this will be used as prefix for line based
              statements.  See also :ref:`line-statements`.
  
          `line_comment_prefix`
              If given and a string, this will be used as prefix for line based
              comments.  See also :ref:`line-statements`.
  
              .. versionadded:: 2.2
  
          `trim_blocks`
              If this is set to ``True`` the first newline after a block is
              removed (block, not variable tag!).  Defaults to `False`.
  
          `lstrip_blocks`
              If this is set to ``True`` leading spaces and tabs are stripped
              from the start of a line to a block.  Defaults to `False`.
  
          `newline_sequence`
              The sequence that starts a newline.  Must be one of ``'\r'``,
              ``'\n'`` or ``'\r\n'``.  The default is ``'\n'`` which is a
              useful default for Linux and OS X systems as well as web
              applications.
  
          `keep_trailing_newline`
              Preserve the trailing newline when rendering templates.
              The default is ``False``, which causes a single newline,
              if present, to be stripped from the end of the template.
  
              .. versionadded:: 2.7
  
          `extensions`
              List of Jinja extensions to use.  This can either be import paths
              as strings or extension classes.  For more information have a
              look at :ref:`the extensions documentation <jinja-extensions>`.
  
          `optimized`
              should the optimizer be enabled?  Default is ``True``.
  
          `undefined`
              :class:`Undefined` or a subclass of it that is used to represent
              undefined values in the template.
  
          `finalize`
              A callable that can be used to process the result of a variable
              expression before it is output.  For example one can convert
              ``None`` implicitly into an empty string here.
  
          `autoescape`
              If set to ``True`` the XML/HTML autoescaping feature is enabled by
              default.  For more details about autoescaping see
              :class:`~markupsafe.Markup`.  As of Jinja 2.4 this can also
              be a callable that is passed the template name and has to
              return ``True`` or ``False`` depending on autoescape should be
              enabled by default.
  
              .. versionchanged:: 2.4
                 `autoescape` can now be a function
  
          `loader`
              The template loader for this environment.
  
          `cache_size`
              The size of the cache.  Per default this is ``400`` which means
              that if more than 400 templates are loaded the loader will clean
              out the least recently used template.  If the cache size is set to
              ``0`` templates are recompiled all the time, if the cache size is
              ``-1`` the cache will not be cleaned.
  
              .. versionchanged:: 2.8
                 The cache size was increased to 400 from a low 50.
  
          `auto_reload`
              Some loaders load templates from locations where the template
              sources may change (ie: file system or database).  If
              ``auto_reload`` is set to ``True`` (default) every time a template is
              requested the loader checks if the source changed and if yes, it
              will reload the template.  For higher performance it's possible to
              disable that.
  
          `bytecode_cache`
              If set to a bytecode cache object, this object will provide a
              cache for the internal Jinja bytecode so that templates don't
              have to be parsed if they were not changed.
  
              See :ref:`bytecode-cache` for more information.
  
          `enable_async`
              If set to true this enables async template execution which
              allows using async functions and generators.
      """
  
      #: if this environment is sandboxed.  Modifying this variable won't make
      #: the environment sandboxed though.  For a real sandboxed environment
      #: have a look at jinja2.sandbox.  This flag alone controls the code
      #: generation by the compiler.
      sandboxed = False
  
      #: True if the environment is just an overlay
      overlayed = False
  
      #: the environment this environment is linked to if it is an overlay
      linked_to = None
  
      #: shared environments have this set to `True`.  A shared environment
      #: must not be modified
      shared = False
  
      #: the class that is used for code generation.  See
      #: :class:`~jinja2.compiler.CodeGenerator` for more information.
      code_generator_class = CodeGenerator
  
      #: the context class that is used for templates.  See
      #: :class:`~jinja2.runtime.Context` for more information.
      context_class = Context
  
      template_class = Any
  
      def __init__(
          self,
          block_start_string=BLOCK_START_STRING,
          block_end_string=BLOCK_END_STRING,
          variable_start_string=VARIABLE_START_STRING,
          variable_end_string=VARIABLE_END_STRING,
          comment_start_string=COMMENT_START_STRING,
          comment_end_string=COMMENT_END_STRING,
          line_statement_prefix=LINE_STATEMENT_PREFIX,
          line_comment_prefix=LINE_COMMENT_PREFIX,
          trim_blocks=TRIM_BLOCKS,
          lstrip_blocks=LSTRIP_BLOCKS,
          newline_sequence=NEWLINE_SEQUENCE,
          keep_trailing_newline=KEEP_TRAILING_NEWLINE,
          extensions=(),
          optimized=True,
          undefined=Undefined,
          finalize=None,
          autoescape=False,
          loader=None,
          cache_size=400,
          auto_reload=True,
          bytecode_cache=None,
          enable_async=False,
      ):
          # !!Important notice!!
          #   The constructor accepts quite a few arguments that should be
          #   passed by keyword rather than position.  However it's important to
          #   not change the order of arguments because it's used at least
          #   internally in those cases:
          #       -   spontaneous environments (i18n extension and Template)
          #       -   unittests
          #   If parameter changes are required only add parameters at the end
          #   and don't change the arguments (or the defaults!) of the arguments
          #   existing already.
  
          # lexer / parser information
          self.block_start_string = block_start_string
          self.block_end_string = block_end_string
          self.variable_start_string = variable_start_string
          self.variable_end_string = variable_end_string
          self.comment_start_string = comment_start_string
          self.comment_end_string = comment_end_string
          self.line_statement_prefix = line_statement_prefix
          self.line_comment_prefix = line_comment_prefix
          self.trim_blocks = trim_blocks
          self.lstrip_blocks = lstrip_blocks
          self.newline_sequence = newline_sequence
          self.keep_trailing_newline = keep_trailing_newline
  
          # runtime information
          self.undefined = undefined
          self.optimized = optimized
          self.finalize = finalize
          self.autoescape = autoescape
  
          # defaults
          self.filters = DEFAULT_FILTERS.copy()
          self.tests = DEFAULT_TESTS.copy()
          self.globals = DEFAULT_NAMESPACE.copy()
  
          # set the loader provided
          self.loader = loader
          self.cache = create_cache(cache_size)
          self.bytecode_cache = bytecode_cache
          self.auto_reload = auto_reload
  
          # configurable policies
          self.policies = DEFAULT_POLICIES.copy()
  
          # load extensions
          self.extensions = load_extensions(self, extensions)
  
          self.enable_async = enable_async
          self.is_async = self.enable_async and have_async_gen
          if self.is_async:
              # runs patch_all() to enable async support
              from . import asyncsupport  # noqa: F401
  
          _environment_sanity_check(self)
  
      def add_extension(self, extension):
          """Adds an extension after the environment was created.
  
          .. versionadded:: 2.5
          """
          self.extensions.update(load_extensions(self, [extension]))
  
      def extend(self, **attributes):
          """Add the items to the instance of the environment if they do not exist
          yet.  This is used by :ref:`extensions <writing-extensions>` to register
          callbacks and configuration values without breaking inheritance.
          """
          for key, value in attributes.items():
              if not hasattr(self, key):
                  setattr(self, key, value)
  
      def overlay(
          self,
          block_start_string=missing,
          block_end_string=missing,
          variable_start_string=missing,
          variable_end_string=missing,
          comment_start_string=missing,
          comment_end_string=missing,
          line_statement_prefix=missing,
          line_comment_prefix=missing,
          trim_blocks=missing,
          lstrip_blocks=missing,
          extensions=missing,
          optimized=missing,
          undefined=missing,
          finalize=missing,
          autoescape=missing,
          loader=missing,
          cache_size=missing,
          auto_reload=missing,
          bytecode_cache=missing,
      ):
          """Create a new overlay environment that shares all the data with the
          current environment except for cache and the overridden attributes.
          Extensions cannot be removed for an overlayed environment.  An overlayed
          environment automatically gets all the extensions of the environment it
          is linked to plus optional extra extensions.
  
          Creating overlays should happen after the initial environment was set
          up completely.  Not all attributes are truly linked, some are just
          copied over so modifications on the original environment may not shine
          through.
          """
          args = dict(locals())
          del args["self"], args["cache_size"], args["extensions"]
  
          rv = object.__new__(self.__class__)
          rv.__dict__.update(self.__dict__)
          rv.overlayed = True
          rv.linked_to = self
  
          for key, value in args.items():
              if value is not missing:
                  setattr(rv, key, value)
  
          if cache_size is not missing:
              rv.cache = create_cache(cache_size)
          else:
              rv.cache = copy_cache(self.cache)
  
          rv.extensions = {}
          for key, value in self.extensions.items():
              rv.extensions[key] = value.bind(rv)
          if extensions is not missing:
              rv.extensions.update(load_extensions(rv, extensions))
  
          return _environment_sanity_check(rv)
  
      lexer = property(get_lexer, doc="The lexer for this environment.")
  
      def iter_extensions(self):
          """Iterates over the extensions by priority."""
          return iter(sorted(self.extensions.values(), key=lambda x: x.priority))
  
      def getitem(self, obj, argument):
          """Get an item or attribute of an object but prefer the item."""
          try:
              return obj[argument]
          except (AttributeError, TypeError, LookupError):
              if isinstance(argument, str):
                  try:
                      attr = str(argument)
                  except Exception:
                      pass
                  else:
                      try:
                          return getattr(obj, attr)
                      except AttributeError:
                          pass
              return self.undefined(obj=obj, name=argument)
  
      def getattr(self, obj, attribute):
          """Get an item or attribute of an object but prefer the attribute.
          Unlike :meth:`getitem` the attribute *must* be a bytestring.
          """
          try:
              return getattr(obj, attribute)
          except AttributeError:
              pass
          try:
              return obj[attribute]
          except (TypeError, LookupError, AttributeError):
              return self.undefined(obj=obj, name=attribute)
  
      def call_filter(
          self, name, value, args=None, kwargs=None, context=None, eval_ctx=None
      ):
          """Invokes a filter on a value the same way the compiler does.
  
          This might return a coroutine if the filter is running from an
          environment in async mode and the filter supports async
          execution. It's your responsibility to await this if needed.
  
          .. versionadded:: 2.7
          """
          func = self.filters.get(name)
          if func is None:
              fail_for_missing_callable("filter", name)
          args = [value] + list(args or ())
          if getattr(func, "contextfilter", False) is True:
              if context is None:
                  raise TemplateRuntimeError(
                      "Attempted to invoke context filter without context"
                  )
              args.insert(0, context)
          elif getattr(func, "evalcontextfilter", False) is True:
              if eval_ctx is None:
                  if context is not None:
                      eval_ctx = context.eval_ctx
                  else:
                      eval_ctx = EvalContext(self)
              args.insert(0, eval_ctx)
          elif getattr(func, "environmentfilter", False) is True:
              args.insert(0, self)
          return func(*args, **(kwargs or {}))
  
      def call_test(self, name, value, args=None, kwargs=None):
          """Invokes a test on a value the same way the compiler does it.
  
          .. versionadded:: 2.7
          """
          func = self.tests.get(name)
          if func is None:
              fail_for_missing_callable("test", name)
          return func(value, *(args or ()), **(kwargs or {}))
  
      @internalcode
      def parse(self, source, name=None, filename=None):
          """Parse the sourcecode and return the abstract syntax tree.  This
          tree of nodes is used by the compiler to convert the template into
          executable source- or bytecode.  This is useful for debugging or to
          extract information from templates.
  
          If you are :ref:`developing Jinja extensions <writing-extensions>`
          this gives you a good overview of the node tree generated.
          """
          try:
              return self._parse(source, name, filename)
          except TemplateSyntaxError:
              self.handle_exception(source=source)
  
      def _parse(self, source, name, filename):
          """Internal parsing function used by `parse` and `compile`."""
          return Parser(self, source, name, filename).parse()
  
      def lex(self, source, name=None, filename=None):
          """Lex the given sourcecode and return a generator that yields
          tokens as tuples in the form ``(lineno, token_type, value)``.
          This can be useful for :ref:`extension development <writing-extensions>`
          and debugging templates.
  
          This does not perform preprocessing.  If you want the preprocessing
          of the extensions to be applied you have to filter source through
          the :meth:`preprocess` method.
          """
          source = str(source)
          try:
              return self.lexer.tokeniter(source, name, filename)
          except TemplateSyntaxError:
              self.handle_exception(source=source)
  
      def preprocess(self, source, name=None, filename=None):
          """Preprocesses the source with all extensions.  This is automatically
          called for all parsing and compiling methods but *not* for :meth:`lex`
          because there you usually only want the actual source tokenized.
          """
          return reduce(
              lambda s, e: e.preprocess(s, name, filename),
              self.iter_extensions(),
              str(source),
          )
  
      def _tokenize(self, source, name, filename=None, state=None):
          """Called by the parser to do the preprocessing and filtering
          for all the extensions.  Returns a :class:`~jinja2.lexer.TokenStream`.
          """
          source = self.preprocess(source, name, filename)
          stream = self.lexer.tokenize(source, name, filename, state)
          for ext in self.iter_extensions():
              stream = ext.filter_stream(stream)
              if not isinstance(stream, TokenStream):
                  stream = TokenStream(stream, name, filename)
          return stream
  
      def _generate(self, source, name, filename, defer_init=False):
          """Internal hook that can be overridden to hook a different generate
          method in.
  
          .. versionadded:: 2.5
          """
          return generate(
              source,
              self,
              name,
              filename,
              defer_init=defer_init,
              optimized=self.optimized,
          )
  
      def _compile(self, source, filename):
          """Internal hook that can be overridden to hook a different compile
          method in.
  
          .. versionadded:: 2.5
          """
          return compile(source, filename, "exec")
  
      @internalcode
      def compile(self, source, name=None, filename=None, raw=False, defer_init=False):
          """Compile a node or template source code.  The `name` parameter is
          the load name of the template after it was joined using
          :meth:`join_path` if necessary, not the filename on the file system.
          the `filename` parameter is the estimated filename of the template on
          the file system.  If the template came from a database or memory this
          can be omitted.
  
          The return value of this method is a python code object.  If the `raw`
          parameter is `True` the return value will be a string with python
          code equivalent to the bytecode returned otherwise.  This method is
          mainly used internally.
  
          `defer_init` is use internally to aid the module code generator.  This
          causes the generated code to be able to import without the global
          environment variable to be set.
  
          .. versionadded:: 2.4
             `defer_init` parameter added.
          """
          source_hint = None
          try:
              if isinstance(source, str):
                  source_hint = source
                  source = self._parse(source, name, filename)
              source = self._generate(source, name, filename, defer_init=defer_init)
              if raw:
                  return source
              if filename is None:
                  filename = "<template>"
              return self._compile(source, filename)
          except TemplateSyntaxError:
              self.handle_exception(source=source_hint)
  
      def compile_expression(self, source, undefined_to_none=True):
          """A handy helper method that returns a callable that accepts keyword
          arguments that appear as variables in the expression.  If called it
          returns the result of the expression.
  
          This is useful if applications want to use the same rules as Jinja
          in template "configuration files" or similar situations.
  
          Example usage:
  
          >>> env = Environment()
          >>> expr = env.compile_expression('foo == 42')
          >>> expr(foo=23)
          False
          >>> expr(foo=42)
          True
  
          Per default the return value is converted to `None` if the
          expression returns an undefined value.  This can be changed
          by setting `undefined_to_none` to `False`.
  
          >>> env.compile_expression('var')() is None
          True
          >>> env.compile_expression('var', undefined_to_none=False)()
          Undefined
  
          .. versionadded:: 2.1
          """
          parser = Parser(self, source, state="variable")
          try:
              expr = parser.parse_expression()
              if not parser.stream.eos:
                  raise TemplateSyntaxError(
                      "chunk after expression", parser.stream.current.lineno, None, None
                  )
              expr.set_environment(self)
          except TemplateSyntaxError:
              if sys.exc_info() is not None:
                  self.handle_exception(source=source)
  
          body = [nodes.Assign(nodes.Name("result", "store"), expr, lineno=1)]
          template = self.from_string(nodes.Template(body, lineno=1))
          return TemplateExpression(template, undefined_to_none)
  
      def compile_templates(
          self,
          target,
          extensions=None,
          filter_func=None,
          zip="deflated",
          log_function=None,
          ignore_errors=True,
      ):
          """Finds all the templates the loader can find, compiles them
          and stores them in `target`.  If `zip` is `None`, instead of in a
          zipfile, the templates will be stored in a directory.
          By default a deflate zip algorithm is used. To switch to
          the stored algorithm, `zip` can be set to ``'stored'``.
  
          `extensions` and `filter_func` are passed to :meth:`list_templates`.
          Each template returned will be compiled to the target folder or
          zipfile.
  
          By default template compilation errors are ignored.  In case a
          log function is provided, errors are logged.  If you want template
          syntax errors to abort the compilation you can set `ignore_errors`
          to `False` and you will get an exception on syntax errors.
  
          .. versionadded:: 2.4
          """
          from .loaders import ModuleLoader
  
          if log_function is None:
  
              def log_function(x):
                  pass
  
          def write_file(filename, data):
              if zip:
                  info = ZipInfo(filename)
                  info.external_attr = 0o755 << 16
                  zip_file.writestr(info, data)
              else:
                  if isinstance(data, str):
                      data = data.encode("utf8")
  
                  with open(os.path.join(target, filename), "wb") as f:
                      f.write(data)
  
          if zip is not None:
              from zipfile import ZipFile, ZipInfo, ZIP_DEFLATED, ZIP_STORED
  
              zip_file = ZipFile(
                  target, "w", dict(deflated=ZIP_DEFLATED, stored=ZIP_STORED)[zip]
              )
              log_function(f"Compiling into Zip archive {target!r}")
          else:
              if not os.path.isdir(target):
                  os.makedirs(target)
              log_function(f"Compiling into folder {target!r}")
  
          try:
              for name in self.list_templates(extensions, filter_func):
                  source, filename, _ = self.loader.get_source(self, name)
                  try:
                      code = self.compile(source, name, filename, True, True)
                  except TemplateSyntaxError as e:
                      if not ignore_errors:
                          raise
                      log_function(f'Could not compile "{name}": {e}')
                      continue
  
                  filename = ModuleLoader.get_module_filename(name)
  
                  write_file(filename, code)
                  log_function(f'Compiled "{name}" as {filename}')
          finally:
              if zip:
                  zip_file.close()
  
          log_function("Finished compiling templates")
  
      def list_templates(self, extensions=None, filter_func=None):
          """Returns a list of templates for this environment.  This requires
          that the loader supports the loader's
          :meth:`~BaseLoader.list_templates` method.
  
          If there are other files in the template folder besides the
          actual templates, the returned list can be filtered.  There are two
          ways: either `extensions` is set to a list of file extensions for
          templates, or a `filter_func` can be provided which is a callable that
          is passed a template name and should return `True` if it should end up
          in the result list.
  
          If the loader does not support that, a :exc:`TypeError` is raised.
  
          .. versionadded:: 2.4
          """
          names = self.loader.list_templates()
  
          if extensions is not None:
              if filter_func is not None:
                  raise TypeError(
                      "either extensions or filter_func can be passed, but not both"
                  )
  
              def filter_func(x):
                  return "." in x and x.rsplit(".", 1)[1] in extensions
  
          if filter_func is not None:
              names = [name for name in names if filter_func(name)]
  
          return names
  
      def handle_exception(self, source=None):
          """Exception handling helper.  This is used internally to either raise
          rewritten exceptions or return a rendered traceback for the template.
          """
          from .debug import rewrite_traceback_stack
  
          raise rewrite_traceback_stack(source=source)
  
      def join_path(self, template, parent):
          """Join a template with the parent.  By default all the lookups are
          relative to the loader root so this method returns the `template`
          parameter unchanged, but if the paths should be relative to the
          parent template, this function can be used to calculate the real
          template name.
  
          Subclasses may override this method and implement template path
          joining here.
          """
          return template
  
      @internalcode
      def _load_template(self, name, globals):
          if self.loader is None:
              raise TypeError("no loader for this environment specified")
          cache_key = (weakref.ref(self.loader), name)
          if self.cache is not None:
              template = self.cache.get(cache_key)
              if template is not None and (
                  not self.auto_reload or template.is_up_to_date
              ):
                  return template
          template = self.loader.load(self, name, globals)
          if self.cache is not None:
              self.cache[cache_key] = template
          return template
  
      @internalcode
      def get_template(self, name, parent=None, globals=None):
          """Load a template from the loader.  If a loader is configured this
          method asks the loader for the template and returns a :class:`Template`.
          If the `parent` parameter is not `None`, :meth:`join_path` is called
          to get the real template name before loading.
  
          The `globals` parameter can be used to provide template wide globals.
          These variables are available in the context at render time.
  
          If the template does not exist a :exc:`TemplateNotFound` exception is
          raised.
  
          .. versionchanged:: 2.4
             If `name` is a :class:`Template` object it is returned from the
             function unchanged.
          """
          if isinstance(name, Template):
              return name
          if parent is not None:
              name = self.join_path(name, parent)
          return self._load_template(name, self.make_globals(globals))
  
      @internalcode
      def select_template(self, names, parent=None, globals=None):
          """Works like :meth:`get_template` but tries a number of templates
          before it fails.  If it cannot find any of the templates, it will
          raise a :exc:`TemplatesNotFound` exception.
  
          .. versionchanged:: 2.11
              If names is :class:`Undefined`, an :exc:`UndefinedError` is
              raised instead. If no templates were found and names
              contains :class:`Undefined`, the message is more helpful.
  
          .. versionchanged:: 2.4
             If `names` contains a :class:`Template` object it is returned
             from the function unchanged.
  
          .. versionadded:: 2.3
          """
          if isinstance(names, Undefined):
              names._fail_with_undefined_error()
  
          if not names:
              raise TemplatesNotFound(
                  message="Tried to select from an empty list of templates."
              )
          globals = self.make_globals(globals)
          for name in names:
              if isinstance(name, Template):
                  return name
              if parent is not None:
                  name = self.join_path(name, parent)
              try:
                  return self._load_template(name, globals)
              except (TemplateNotFound, UndefinedError):
                  pass
          raise TemplatesNotFound(names)
  
      @internalcode
      def get_or_select_template(self, template_name_or_list, parent=None, globals=None):
          """Does a typecheck and dispatches to :meth:`select_template`
          if an iterable of template names is given, otherwise to
          :meth:`get_template`.
  
          .. versionadded:: 2.3
          """
          if isinstance(template_name_or_list, (str, Undefined)):
              return self.get_template(template_name_or_list, parent, globals)
          elif isinstance(template_name_or_list, Template):
              return template_name_or_list
          return self.select_template(template_name_or_list, parent, globals)
  
      def from_string(self, source, globals=None, template_class=None):
          """Load a template from a string.  This parses the source given and
          returns a :class:`Template` object.
          """
          globals = self.make_globals(globals)
          cls = template_class or self.template_class
          return cls.from_code(self, self.compile(source), globals, None)
  
      def make_globals(self, d):
          """Return a dict for the globals."""
          if not d:
              return self.globals
          return dict(self.globals, **d)
  
  
  class Template:
      """The central template object.  This class represents a compiled template
      and is used to evaluate it.
  
      Normally the template object is generated from an :class:`Environment` but
      it also has a constructor that makes it possible to create a template
      instance directly using the constructor.  It takes the same arguments as
      the environment constructor but it's not possible to specify a loader.
  
      Every template object has a few methods and members that are guaranteed
      to exist.  However it's important that a template object should be
      considered immutable.  Modifications on the object are not supported.
  
      Template objects created from the constructor rather than an environment
      do have an `environment` attribute that points to a temporary environment
      that is probably shared with other templates created with the constructor
      and compatible settings.
  
      >>> template = Template('Hello {{ name }}!')
      >>> template.render(name='John Doe') == u'Hello John Doe!'
      True
      >>> stream = template.stream(name='John Doe')
      >>> next(stream) == u'Hello John Doe!'
      True
      >>> next(stream)
      Traceback (most recent call last):
          ...
      StopIteration
      """
  
      #: Type of environment to create when creating a template directly
      #: rather than through an existing environment.
      environment_class = Environment
  
      def __new__(
          cls,
          source,
          block_start_string=BLOCK_START_STRING,
          block_end_string=BLOCK_END_STRING,
          variable_start_string=VARIABLE_START_STRING,
          variable_end_string=VARIABLE_END_STRING,
          comment_start_string=COMMENT_START_STRING,
          comment_end_string=COMMENT_END_STRING,
          line_statement_prefix=LINE_STATEMENT_PREFIX,
          line_comment_prefix=LINE_COMMENT_PREFIX,
          trim_blocks=TRIM_BLOCKS,
          lstrip_blocks=LSTRIP_BLOCKS,
          newline_sequence=NEWLINE_SEQUENCE,
          keep_trailing_newline=KEEP_TRAILING_NEWLINE,
          extensions=(),
          optimized=True,
          undefined=Undefined,
          finalize=None,
          autoescape=False,
          enable_async=False,
      ):
          env = get_spontaneous_environment(
              cls.environment_class,
              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,
              lstrip_blocks,
              newline_sequence,
              keep_trailing_newline,
              frozenset(extensions),
              optimized,
              undefined,
              finalize,
              autoescape,
              None,
              0,
              False,
              None,
              enable_async,
          )
          return env.from_string(source, template_class=cls)
  
      @classmethod
      def from_code(cls, environment, code, globals, uptodate=None):
          """Creates a template object from compiled code and the globals.  This
          is used by the loaders and environment to create a template object.
          """
          namespace = {"environment": environment, "__file__": code.co_filename}
          exec(code, namespace)
          rv = cls._from_namespace(environment, namespace, globals)
          rv._uptodate = uptodate
          return rv
  
      @classmethod
      def from_module_dict(cls, environment, module_dict, globals):
          """Creates a template object from a module.  This is used by the
          module loader to create a template object.
  
          .. versionadded:: 2.4
          """
          return cls._from_namespace(environment, module_dict, globals)
  
      @classmethod
      def _from_namespace(cls, environment, namespace, globals):
          t = object.__new__(cls)
          t.environment = environment
          t.globals = globals
          t.name = namespace["name"]
          t.filename = namespace["__file__"]
          t.blocks = namespace["blocks"]
  
          # render function and module
          t.root_render_func = namespace["root"]
          t._module = None
  
          # debug and loader helpers
          t._debug_info = namespace["debug_info"]
          t._uptodate = None
  
          # store the reference
          namespace["environment"] = environment
          namespace["__jinja_template__"] = t
  
          return t
  
      def render(self, *args, **kwargs):
          """This method accepts the same arguments as the `dict` constructor:
          A dict, a dict subclass or some keyword arguments.  If no arguments
          are given the context will be empty.  These two calls do the same::
  
              template.render(knights='that say nih')
              template.render({'knights': 'that say nih'})
  
          This will return the rendered template as a string.
          """
          vars = dict(*args, **kwargs)
          try:
              return concat(self.root_render_func(self.new_context(vars)))
          except Exception:
              self.environment.handle_exception()
  
      def render_async(self, *args, **kwargs):
          """This works similar to :meth:`render` but returns a coroutine
          that when awaited returns the entire rendered template string.  This
          requires the async feature to be enabled.
  
          Example usage::
  
              await template.render_async(knights='that say nih; asynchronously')
          """
          # see asyncsupport for the actual implementation
          raise NotImplementedError(
              "This feature is not available for this version of Python"
          )
  
      def stream(self, *args, **kwargs):
          """Works exactly like :meth:`generate` but returns a
          :class:`TemplateStream`.
          """
          return TemplateStream(self.generate(*args, **kwargs))
  
      def generate(self, *args, **kwargs):
          """For very large templates it can be useful to not render the whole
          template at once but evaluate each statement after another and yield
          piece for piece.  This method basically does exactly that and returns
          a generator that yields one item after another as strings.
  
          It accepts the same arguments as :meth:`render`.
          """
          vars = dict(*args, **kwargs)
          try:
              yield from self.root_render_func(self.new_context(vars))
          except Exception:
              yield self.environment.handle_exception()
  
      def generate_async(self, *args, **kwargs):
          """An async version of :meth:`generate`.  Works very similarly but
          returns an async iterator instead.
          """
          # see asyncsupport for the actual implementation
          raise NotImplementedError(
              "This feature is not available for this version of Python"
          )
  
      def new_context(self, vars=None, shared=False, locals=None):
          """Create a new :class:`Context` for this template.  The vars
          provided will be passed to the template.  Per default the globals
          are added to the context.  If shared is set to `True` the data
          is passed as is to the context without adding the globals.
  
          `locals` can be a dict of local variables for internal usage.
          """
          return new_context(
              self.environment, self.name, self.blocks, vars, shared, self.globals, locals
          )
  
      def make_module(self, vars=None, shared=False, locals=None):
          """This method works like the :attr:`module` attribute when called
          without arguments but it will evaluate the template on every call
          rather than caching it.  It's also possible to provide
          a dict which is then used as context.  The arguments are the same
          as for the :meth:`new_context` method.
          """
          return TemplateModule(self, self.new_context(vars, shared, locals))
  
      def make_module_async(self, vars=None, shared=False, locals=None):
          """As template module creation can invoke template code for
          asynchronous executions this method must be used instead of the
          normal :meth:`make_module` one.  Likewise the module attribute
          becomes unavailable in async mode.
          """
          # see asyncsupport for the actual implementation
          raise NotImplementedError(
              "This feature is not available for this version of Python"
          )
  
      @internalcode
      def _get_default_module(self, ctx=None):
          """If a context is passed in, this means that the template was
          imported.  Imported templates have access to the current template's
          globals by default, but they can only be accessed via the context
          during runtime.
  
          If there are new globals, we need to create a new
          module because the cached module is already rendered and will not have
          access to globals from the current context.  This new module is not
          cached as :attr:`_module` because the template can be imported elsewhere,
          and it should have access to only the current template's globals.
          """
          if ctx is not None:
              globals = {
                  key: ctx.parent[key] for key in ctx.globals_keys - self.globals.keys()
              }
              if globals:
                  return self.make_module(globals)
          if self._module is not None:
              return self._module
          self._module = rv = self.make_module()
          return rv
  
      @property
      def module(self):
          """The template as module.  This is used for imports in the
          template runtime but is also useful if one wants to access
          exported template variables from the Python layer:
  
          >>> t = Template('{% macro foo() %}42{% endmacro %}23')
          >>> str(t.module)
          '23'
          >>> t.module.foo() == u'42'
          True
  
          This attribute is not available if async mode is enabled.
          """
          return self._get_default_module()
  
      def get_corresponding_lineno(self, lineno):
          """Return the source line number of a line number in the
          generated bytecode as they are not in sync.
          """
          for template_line, code_line in reversed(self.debug_info):
              if code_line <= lineno:
                  return template_line
          return 1
  
      @property
      def is_up_to_date(self):
          """If this variable is `False` there is a newer version available."""
          if self._uptodate is None:
              return True
          return self._uptodate()
  
      @property
      def debug_info(self):
          """The debug info mapping."""
          if self._debug_info:
              return [tuple(map(int, x.split("="))) for x in self._debug_info.split("&")]
          return []
  
      def __repr__(self):
          if self.name is None:
              name = f"memory:{id(self):x}"
          else:
              name = repr(self.name)
          return f"<{self.__class__.__name__} {name}>"
  
  
  class TemplateModule:
      """Represents an imported template.  All the exported names of the
      template are available as attributes on this object.  Additionally
      converting it into a string renders the contents.
      """
  
      def __init__(self, template, context, body_stream=None):
          if body_stream is None:
              if context.environment.is_async:
                  raise RuntimeError(
                      "Async mode requires a body stream "
                      "to be passed to a template module.  Use "
                      "the async methods of the API you are "
                      "using."
                  )
              body_stream = list(template.root_render_func(context))
          self._body_stream = body_stream
          self.__dict__.update(context.get_exported())
          self.__name__ = template.name
  
      def __html__(self):
          return Markup(concat(self._body_stream))
  
      def __str__(self):
          return concat(self._body_stream)
  
      def __repr__(self):
          if self.__name__ is None:
              name = f"memory:{id(self):x}"
          else:
              name = repr(self.__name__)
          return f"<{self.__class__.__name__} {name}>"
  
  
  class TemplateExpression:
      """The :meth:`jinja2.Environment.compile_expression` method returns an
      instance of this object.  It encapsulates the expression-like access
      to the template with an expression it wraps.
      """
  
      def __init__(self, template, undefined_to_none):
          self._template = template
          self._undefined_to_none = undefined_to_none
  
      def __call__(self, *args, **kwargs):
          context = self._template.new_context(dict(*args, **kwargs))
          consume(self._template.root_render_func(context))
          rv = context.vars["result"]
          if self._undefined_to_none and isinstance(rv, Undefined):
              rv = None
          return rv
  
  
  class TemplateStream:
      """A template stream works pretty much like an ordinary python generator
      but it can buffer multiple items to reduce the number of total iterations.
      Per default the output is unbuffered which means that for every unbuffered
      instruction in the template one string is yielded.
  
      If buffering is enabled with a buffer size of 5, five items are combined
      into a new string.  This is mainly useful if you are streaming
      big templates to a client via WSGI which flushes after each iteration.
      """
  
      def __init__(self, gen):
          self._gen = gen
          self.disable_buffering()
  
      def dump(self, fp, encoding=None, errors="strict"):
          """Dump the complete stream into a file or file-like object.
          Per default strings are written, if you want to encode
          before writing specify an `encoding`.
  
          Example usage::
  
              Template('Hello {{ name }}!').stream(name='foo').dump('hello.html')
          """
          close = False
          if isinstance(fp, str):
              if encoding is None:
                  encoding = "utf-8"
              fp = open(fp, "wb")
              close = True
          try:
              if encoding is not None:
                  iterable = (x.encode(encoding, errors) for x in self)
              else:
                  iterable = self
              if hasattr(fp, "writelines"):
                  fp.writelines(iterable)
              else:
                  for item in iterable:
                      fp.write(item)
          finally:
              if close:
                  fp.close()
  
      def disable_buffering(self):
          """Disable the output buffering."""
          self._next = partial(next, self._gen)
          self.buffered = False
  
      def _buffered_generator(self, size):
          buf = []
          c_size = 0
          push = buf.append
  
          while 1:
              try:
                  while c_size < size:
                      c = next(self._gen)
                      push(c)
                      if c:
                          c_size += 1
              except StopIteration:
                  if not c_size:
                      return
              yield concat(buf)
              del buf[:]
              c_size = 0
  
      def enable_buffering(self, size=5):
          """Enable buffering.  Buffer `size` items before yielding them."""
          if size <= 1:
              raise ValueError("buffer size too small")
  
          self.buffered = True
          self._next = partial(next, self._buffered_generator(size))
  
      def __iter__(self):
          return self
  
      def __next__(self):
          return self._next()
  
  
  # hook in default template class.  if anyone reads this comment: ignore that
  # it's possible to use custom templates ;-)
  Environment.template_class = Template
  