Current File : //usr/lib/python3/dist-packages/jinja2/runtime.py
"""The runtime functions and state used by compiled templates."""
import functools
import sys
import typing as t
from collections import abc
from itertools import chain
from markupsafe import escape # noqa: F401
from markupsafe import Markup
from markupsafe import soft_str
from .async_utils import auto_aiter
from .async_utils import auto_await # noqa: F401
from .exceptions import TemplateNotFound # noqa: F401
from .exceptions import TemplateRuntimeError # noqa: F401
from .exceptions import UndefinedError
from .nodes import EvalContext
from .utils import _PassArg
from .utils import concat
from .utils import internalcode
from .utils import missing
from .utils import Namespace # noqa: F401
from .utils import object_type_repr
from .utils import pass_eval_context
V = t.TypeVar("V")
F = t.TypeVar("F", bound=t.Callable[..., t.Any])
if t.TYPE_CHECKING:
import logging
import typing_extensions as te
from .environment import Environment
class LoopRenderFunc(te.Protocol):
def __call__(
self,
reciter: t.Iterable[V],
loop_render_func: "LoopRenderFunc",
depth: int = 0,
) -> str:
...
# these variables are exported to the template runtime
exported = [
"LoopContext",
"TemplateReference",
"Macro",
"Markup",
"TemplateRuntimeError",
"missing",
"concat",
"escape",
"markup_join",
"str_join",
"identity",
"TemplateNotFound",
"Namespace",
"Undefined",
"internalcode",
]
async_exported = [
"AsyncLoopContext",
"auto_aiter",
"auto_await",
]
def identity(x: V) -> V:
"""Returns its argument. Useful for certain things in the
environment.
"""
return x
def markup_join(seq: t.Iterable[t.Any]) -> str:
"""Concatenation that escapes if necessary and converts to string."""
buf = []
iterator = map(soft_str, seq)
for arg in iterator:
buf.append(arg)
if hasattr(arg, "__html__"):
return Markup("").join(chain(buf, iterator))
return concat(buf)
def str_join(seq: t.Iterable[t.Any]) -> str:
"""Simple args to string conversion and concatenation."""
return concat(map(str, seq))
def unicode_join(seq: t.Iterable[t.Any]) -> str:
import warnings
warnings.warn(
"This template must be recompiled with at least Jinja 3.0, or"
" it will fail in Jinja 3.1.",
DeprecationWarning,
stacklevel=2,
)
return str_join(seq)
def new_context(
environment: "Environment",
template_name: t.Optional[str],
blocks: t.Dict[str, t.Callable[["Context"], t.Iterator[str]]],
vars: t.Optional[t.Dict[str, t.Any]] = None,
shared: bool = False,
globals: t.Optional[t.MutableMapping[str, t.Any]] = None,
locals: t.Optional[t.Mapping[str, t.Any]] = None,
) -> "Context":
"""Internal helper for context creation."""
if vars is None:
vars = {}
if shared:
parent = vars
else:
parent = dict(globals or (), **vars)
if locals:
# if the parent is shared a copy should be created because
# we don't want to modify the dict passed
if shared:
parent = dict(parent)
for key, value in locals.items():
if value is not missing:
parent[key] = value
return environment.context_class(
environment, parent, template_name, blocks, globals=globals
)
class TemplateReference:
"""The `self` in templates."""
def __init__(self, context: "Context") -> None:
self.__context = context
def __getitem__(self, name: str) -> t.Any:
blocks = self.__context.blocks[name]
return BlockReference(name, self.__context, blocks, 0)
def __repr__(self) -> str:
return f"<{type(self).__name__} {self.__context.name!r}>"
def _dict_method_all(dict_method: F) -> F:
@functools.wraps(dict_method)
def f_all(self: "Context") -> t.Any:
return dict_method(self.get_all())
return t.cast(F, f_all)
@abc.Mapping.register
class Context:
"""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:`pass_context` 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.
"""
_legacy_resolve_mode: t.ClassVar[bool] = False
def __init_subclass__(cls) -> None:
if "resolve_or_missing" in cls.__dict__:
# If the subclass overrides resolve_or_missing it opts in to
# modern mode no matter what.
cls._legacy_resolve_mode = False
elif "resolve" in cls.__dict__ or cls._legacy_resolve_mode:
# If the subclass overrides resolve, or if its base is
# already in legacy mode, warn about legacy behavior.
import warnings
warnings.warn(
"Overriding 'resolve' is deprecated and will not have"
" the expected behavior in Jinja 3.1. Override"
" 'resolve_or_missing' instead ",
DeprecationWarning,
stacklevel=2,
)
cls._legacy_resolve_mode = True
def __init__(
self,
environment: "Environment",
parent: t.Dict[str, t.Any],
name: t.Optional[str],
blocks: t.Dict[str, t.Callable[["Context"], t.Iterator[str]]],
globals: t.Optional[t.MutableMapping[str, t.Any]] = None,
):
self.parent = parent
self.vars: t.Dict[str, t.Any] = {}
self.environment: "Environment" = environment
self.eval_ctx = EvalContext(self.environment, name)
self.exported_vars: t.Set[str] = set()
self.name = name
self.globals_keys = set() if globals is None else set(globals)
# 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 = {k: [v] for k, v in blocks.items()}
def super(
self, name: str, current: t.Callable[["Context"], t.Iterator[str]]
) -> t.Union["BlockReference", "Undefined"]:
"""Render a parent block."""
try:
blocks = self.blocks[name]
index = blocks.index(current) + 1
blocks[index]
except LookupError:
return self.environment.undefined(
f"there is no parent block called {name!r}.", name="super"
)
return BlockReference(name, self, blocks, index)
def get(self, key: str, default: t.Any = None) -> t.Any:
"""Look up a variable by name, or return a default if the key is
not found.
:param key: The variable name to look up.
:param default: The value to return if the key is not found.
"""
try:
return self[key]
except KeyError:
return default
def resolve(self, key: str) -> t.Union[t.Any, "Undefined"]:
"""Look up a variable by name, or return an :class:`Undefined`
object if the key is not found.
If you need to add custom behavior, override
:meth:`resolve_or_missing`, not this method. The various lookup
functions use that method, not this one.
:param key: The variable name to look up.
"""
if self._legacy_resolve_mode:
if key in self.vars:
return self.vars[key]
if key in self.parent:
return self.parent[key]
return self.environment.undefined(name=key)
rv = self.resolve_or_missing(key)
if rv is missing:
return self.environment.undefined(name=key)
return rv
def resolve_or_missing(self, key: str) -> t.Any:
"""Look up a variable by name, or return a ``missing`` sentinel
if the key is not found.
Override this method to add custom lookup behavior.
:meth:`resolve`, :meth:`get`, and :meth:`__getitem__` use this
method. Don't call this method directly.
:param key: The variable name to look up.
"""
if self._legacy_resolve_mode:
rv = self.resolve(key)
if isinstance(rv, Undefined):
return missing
return rv
if key in self.vars:
return self.vars[key]
if key in self.parent:
return self.parent[key]
return missing
def get_exported(self) -> t.Dict[str, t.Any]:
"""Get a new dict with the exported variables."""
return {k: self.vars[k] for k in self.exported_vars}
def get_all(self) -> t.Dict[str, t.Any]:
"""Return the complete context as dict including the exported
variables. For optimizations reasons this might not return an
actual copy so be careful with using it.
"""
if not self.vars:
return self.parent
if not self.parent:
return self.vars
return dict(self.parent, **self.vars)
@internalcode
def call(
__self, __obj: t.Callable, *args: t.Any, **kwargs: t.Any # noqa: B902
) -> t.Union[t.Any, "Undefined"]:
"""Call the callable with the arguments and keyword arguments
provided but inject the active context or environment as first
argument if the callable has :func:`pass_context` or
:func:`pass_environment`.
"""
if __debug__:
__traceback_hide__ = True # noqa
# Allow callable classes to take a context
if (
hasattr(__obj, "__call__") # noqa: B004
and _PassArg.from_obj(__obj.__call__) is not None # type: ignore
):
__obj = __obj.__call__ # type: ignore
pass_arg = _PassArg.from_obj(__obj)
if pass_arg is _PassArg.context:
# the active context should have access to variables set in
# loops and blocks without mutating the context itself
if kwargs.get("_loop_vars"):
__self = __self.derived(kwargs["_loop_vars"])
if kwargs.get("_block_vars"):
__self = __self.derived(kwargs["_block_vars"])
args = (__self,) + args
elif pass_arg is _PassArg.eval_context:
args = (__self.eval_ctx,) + args
elif pass_arg is _PassArg.environment:
args = (__self.environment,) + args
kwargs.pop("_block_vars", None)
kwargs.pop("_loop_vars", None)
try:
return __obj(*args, **kwargs)
except StopIteration:
return __self.environment.undefined(
"value was undefined because a callable raised a"
" StopIteration exception"
)
def derived(self, locals: t.Optional[t.Dict[str, t.Any]] = None) -> "Context":
"""Internal helper function to create a derived context. This is
used in situations where the system needs a new context in the same
template that is independent.
"""
context = new_context(
self.environment, self.name, {}, self.get_all(), True, None, locals
)
context.eval_ctx = self.eval_ctx
context.blocks.update((k, list(v)) for k, v in self.blocks.items())
return context
keys = _dict_method_all(dict.keys)
values = _dict_method_all(dict.values)
items = _dict_method_all(dict.items)
def __contains__(self, name: str) -> bool:
return name in self.vars or name in self.parent
def __getitem__(self, key: str) -> t.Any:
"""Look up a variable by name with ``[]`` syntax, or raise a
``KeyError`` if the key is not found.
"""
item = self.resolve_or_missing(key)
if item is missing:
raise KeyError(key)
return item
def __repr__(self) -> str:
return f"<{type(self).__name__} {self.get_all()!r} of {self.name!r}>"
class BlockReference:
"""One block on a template reference."""
def __init__(
self,
name: str,
context: "Context",
stack: t.List[t.Callable[["Context"], t.Iterator[str]]],
depth: int,
) -> None:
self.name = name
self._context = context
self._stack = stack
self._depth = depth
@property
def super(self) -> t.Union["BlockReference", "Undefined"]:
"""Super the block."""
if self._depth + 1 >= len(self._stack):
return self._context.environment.undefined(
f"there is no parent block called {self.name!r}.", name="super"
)
return BlockReference(self.name, self._context, self._stack, self._depth + 1)
@internalcode
async def _async_call(self) -> str:
rv = concat(
[x async for x in self._stack[self._depth](self._context)] # type: ignore
)
if self._context.eval_ctx.autoescape:
return Markup(rv)
return rv
@internalcode
def __call__(self) -> str:
if self._context.environment.is_async:
return self._async_call() # type: ignore
rv = concat(self._stack[self._depth](self._context))
if self._context.eval_ctx.autoescape:
return Markup(rv)
return rv
class LoopContext:
"""A wrapper iterable for dynamic ``for`` loops, with information
about the loop and iteration.
"""
#: Current iteration of the loop, starting at 0.
index0 = -1
_length: t.Optional[int] = None
_after: t.Any = missing
_current: t.Any = missing
_before: t.Any = missing
_last_changed_value: t.Any = missing
def __init__(
self,
iterable: t.Iterable[V],
undefined: t.Type["Undefined"],
recurse: t.Optional["LoopRenderFunc"] = None,
depth0: int = 0,
) -> None:
"""
:param iterable: Iterable to wrap.
:param undefined: :class:`Undefined` class to use for next and
previous items.
:param recurse: The function to render the loop body when the
loop is marked recursive.
:param depth0: Incremented when looping recursively.
"""
self._iterable = iterable
self._iterator = self._to_iterator(iterable)
self._undefined = undefined
self._recurse = recurse
#: How many levels deep a recursive loop currently is, starting at 0.
self.depth0 = depth0
@staticmethod
def _to_iterator(iterable: t.Iterable[V]) -> t.Iterator[V]:
return iter(iterable)
@property
def length(self) -> int:
"""Length of the iterable.
If the iterable is a generator or otherwise does not have a
size, it is eagerly evaluated to get a size.
"""
if self._length is not None:
return self._length
try:
self._length = len(self._iterable) # type: ignore
except TypeError:
iterable = list(self._iterator)
self._iterator = self._to_iterator(iterable)
self._length = len(iterable) + self.index + (self._after is not missing)
return self._length
def __len__(self) -> int:
return self.length
@property
def depth(self) -> int:
"""How many levels deep a recursive loop currently is, starting at 1."""
return self.depth0 + 1
@property
def index(self) -> int:
"""Current iteration of the loop, starting at 1."""
return self.index0 + 1
@property
def revindex0(self) -> int:
"""Number of iterations from the end of the loop, ending at 0.
Requires calculating :attr:`length`.
"""
return self.length - self.index
@property
def revindex(self) -> int:
"""Number of iterations from the end of the loop, ending at 1.
Requires calculating :attr:`length`.
"""
return self.length - self.index0
@property
def first(self) -> bool:
"""Whether this is the first iteration of the loop."""
return self.index0 == 0
def _peek_next(self) -> t.Any:
"""Return the next element in the iterable, or :data:`missing`
if the iterable is exhausted. Only peeks one item ahead, caching
the result in :attr:`_last` for use in subsequent checks. The
cache is reset when :meth:`__next__` is called.
"""
if self._after is not missing:
return self._after
self._after = next(self._iterator, missing)
return self._after
@property
def last(self) -> bool:
"""Whether this is the last iteration of the loop.
Causes the iterable to advance early. See
:func:`itertools.groupby` for issues this can cause.
The :func:`groupby` filter avoids that issue.
"""
return self._peek_next() is missing
@property
def previtem(self) -> t.Union[t.Any, "Undefined"]:
"""The item in the previous iteration. Undefined during the
first iteration.
"""
if self.first:
return self._undefined("there is no previous item")
return self._before
@property
def nextitem(self) -> t.Union[t.Any, "Undefined"]:
"""The item in the next iteration. Undefined during the last
iteration.
Causes the iterable to advance early. See
:func:`itertools.groupby` for issues this can cause.
The :func:`jinja-filters.groupby` filter avoids that issue.
"""
rv = self._peek_next()
if rv is missing:
return self._undefined("there is no next item")
return rv
def cycle(self, *args: V) -> V:
"""Return a value from the given args, cycling through based on
the current :attr:`index0`.
:param args: One or more values to cycle through.
"""
if not args:
raise TypeError("no items for cycling given")
return args[self.index0 % len(args)]
def changed(self, *value: t.Any) -> bool:
"""Return ``True`` if previously called with a different value
(including when called for the first time).
:param value: One or more values to compare to the last call.
"""
if self._last_changed_value != value:
self._last_changed_value = value
return True
return False
def __iter__(self) -> "LoopContext":
return self
def __next__(self) -> t.Tuple[t.Any, "LoopContext"]:
if self._after is not missing:
rv = self._after
self._after = missing
else:
rv = next(self._iterator)
self.index0 += 1
self._before = self._current
self._current = rv
return rv, self
@internalcode
def __call__(self, iterable: t.Iterable[V]) -> str:
"""When iterating over nested data, render the body of the loop
recursively with the given inner iterable data.
The loop must have the ``recursive`` marker for this to work.
"""
if self._recurse is None:
raise TypeError(
"The loop must have the 'recursive' marker to be called recursively."
)
return self._recurse(iterable, self._recurse, depth=self.depth)
def __repr__(self) -> str:
return f"<{type(self).__name__} {self.index}/{self.length}>"
class AsyncLoopContext(LoopContext):
_iterator: t.AsyncIterator[t.Any] # type: ignore
@staticmethod
def _to_iterator( # type: ignore
iterable: t.Union[t.Iterable[V], t.AsyncIterable[V]]
) -> t.AsyncIterator[V]:
return auto_aiter(iterable)
@property
async def length(self) -> int: # type: ignore
if self._length is not None:
return self._length
try:
self._length = len(self._iterable) # type: ignore
except TypeError:
iterable = [x async for x in self._iterator]
self._iterator = self._to_iterator(iterable)
self._length = len(iterable) + self.index + (self._after is not missing)
return self._length
@property
async def revindex0(self) -> int: # type: ignore
return await self.length - self.index
@property
async def revindex(self) -> int: # type: ignore
return await self.length - self.index0
async def _peek_next(self) -> t.Any:
if self._after is not missing:
return self._after
try:
self._after = await self._iterator.__anext__()
except StopAsyncIteration:
self._after = missing
return self._after
@property
async def last(self) -> bool: # type: ignore
return await self._peek_next() is missing
@property
async def nextitem(self) -> t.Union[t.Any, "Undefined"]:
rv = await self._peek_next()
if rv is missing:
return self._undefined("there is no next item")
return rv
def __aiter__(self) -> "AsyncLoopContext":
return self
async def __anext__(self) -> t.Tuple[t.Any, "AsyncLoopContext"]:
if self._after is not missing:
rv = self._after
self._after = missing
else:
rv = await self._iterator.__anext__()
self.index0 += 1
self._before = self._current
self._current = rv
return rv, self
class Macro:
"""Wraps a macro function."""
def __init__(
self,
environment: "Environment",
func: t.Callable[..., str],
name: str,
arguments: t.List[str],
catch_kwargs: bool,
catch_varargs: bool,
caller: bool,
default_autoescape: t.Optional[bool] = None,
):
self._environment = environment
self._func = func
self._argument_count = len(arguments)
self.name = name
self.arguments = arguments
self.catch_kwargs = catch_kwargs
self.catch_varargs = catch_varargs
self.caller = caller
self.explicit_caller = "caller" in arguments
if default_autoescape is None:
if callable(environment.autoescape):
default_autoescape = environment.autoescape(None)
else:
default_autoescape = environment.autoescape
self._default_autoescape = default_autoescape
@internalcode
@pass_eval_context
def __call__(self, *args: t.Any, **kwargs: t.Any) -> str:
# This requires a bit of explanation, In the past we used to
# decide largely based on compile-time information if a macro is
# safe or unsafe. While there was a volatile mode it was largely
# unused for deciding on escaping. This turns out to be
# problematic for macros because whether a macro is safe depends not
# on the escape mode when it was defined, but rather when it was used.
#
# Because however we export macros from the module system and
# there are historic callers that do not pass an eval context (and
# will continue to not pass one), we need to perform an instance
# check here.
#
# This is considered safe because an eval context is not a valid
# argument to callables otherwise anyway. Worst case here is
# that if no eval context is passed we fall back to the compile
# time autoescape flag.
if args and isinstance(args[0], EvalContext):
autoescape = args[0].autoescape
args = args[1:]
else:
autoescape = self._default_autoescape
# try to consume the positional arguments
arguments = list(args[: self._argument_count])
off = len(arguments)
# For information why this is necessary refer to the handling
# of caller in the `macro_body` handler in the compiler.
found_caller = False
# if the number of arguments consumed is not the number of
# arguments expected we start filling in keyword arguments
# and defaults.
if off != self._argument_count:
for name in self.arguments[len(arguments) :]:
try:
value = kwargs.pop(name)
except KeyError:
value = missing
if name == "caller":
found_caller = True
arguments.append(value)
else:
found_caller = self.explicit_caller
# 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 and not found_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:
if "caller" in kwargs:
raise TypeError(
f"macro {self.name!r} was invoked with two values for the special"
" caller argument. This is most likely a bug."
)
raise TypeError(
f"macro {self.name!r} takes no keyword argument {next(iter(kwargs))!r}"
)
if self.catch_varargs:
arguments.append(args[self._argument_count :])
elif len(args) > self._argument_count:
raise TypeError(
f"macro {self.name!r} takes not more than"
f" {len(self.arguments)} argument(s)"
)
return self._invoke(arguments, autoescape)
async def _async_invoke(self, arguments: t.List[t.Any], autoescape: bool) -> str:
rv = await self._func(*arguments) # type: ignore
if autoescape:
return Markup(rv)
return rv # type: ignore
def _invoke(self, arguments: t.List[t.Any], autoescape: bool) -> str:
if self._environment.is_async:
return self._async_invoke(arguments, autoescape) # type: ignore
rv = self._func(*arguments)
if autoescape:
rv = Markup(rv)
return rv
def __repr__(self) -> str:
name = "anonymous" if self.name is None else repr(self.name)
return f"<{type(self).__name__} {name}>"
class Undefined:
"""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):
...
jinja2.exceptions.UndefinedError: 'foo' is undefined
"""
__slots__ = (
"_undefined_hint",
"_undefined_obj",
"_undefined_name",
"_undefined_exception",
)
def __init__(
self,
hint: t.Optional[str] = None,
obj: t.Any = missing,
name: t.Optional[str] = None,
exc: t.Type[TemplateRuntimeError] = UndefinedError,
) -> None:
self._undefined_hint = hint
self._undefined_obj = obj
self._undefined_name = name
self._undefined_exception = exc
@property
def _undefined_message(self) -> str:
"""Build a message about the undefined value based on how it was
accessed.
"""
if self._undefined_hint:
return self._undefined_hint
if self._undefined_obj is missing:
return f"{self._undefined_name!r} is undefined"
if not isinstance(self._undefined_name, str):
return (
f"{object_type_repr(self._undefined_obj)} has no"
f" element {self._undefined_name!r}"
)
return (
f"{object_type_repr(self._undefined_obj)!r} has no"
f" attribute {self._undefined_name!r}"
)
@internalcode
def _fail_with_undefined_error(
self, *args: t.Any, **kwargs: t.Any
) -> "te.NoReturn":
"""Raise an :exc:`UndefinedError` when operations are performed
on the undefined value.
"""
raise self._undefined_exception(self._undefined_message)
@internalcode
def __getattr__(self, name: str) -> t.Any:
if name[:2] == "__":
raise AttributeError(name)
return self._fail_with_undefined_error()
__add__ = __radd__ = __sub__ = __rsub__ = _fail_with_undefined_error
__mul__ = __rmul__ = __div__ = __rdiv__ = _fail_with_undefined_error
__truediv__ = __rtruediv__ = _fail_with_undefined_error
__floordiv__ = __rfloordiv__ = _fail_with_undefined_error
__mod__ = __rmod__ = _fail_with_undefined_error
__pos__ = __neg__ = _fail_with_undefined_error
__call__ = __getitem__ = _fail_with_undefined_error
__lt__ = __le__ = __gt__ = __ge__ = _fail_with_undefined_error
__int__ = __float__ = __complex__ = _fail_with_undefined_error
__pow__ = __rpow__ = _fail_with_undefined_error
def __eq__(self, other: t.Any) -> bool:
return type(self) is type(other)
def __ne__(self, other: t.Any) -> bool:
return not self.__eq__(other)
def __hash__(self) -> int:
return id(type(self))
def __str__(self) -> str:
return ""
def __len__(self) -> int:
return 0
def __iter__(self) -> t.Iterator[t.Any]:
yield from ()
async def __aiter__(self) -> t.AsyncIterator[t.Any]:
for _ in ():
yield
def __bool__(self) -> bool:
return False
def __repr__(self) -> str:
return "Undefined"
def make_logging_undefined(
logger: t.Optional["logging.Logger"] = None, base: t.Type[Undefined] = Undefined
) -> t.Type[Undefined]:
"""Given a logger object this returns a new undefined class that will
log certain failures. It will log iterations and printing. If no
logger is given a default logger is created.
Example::
logger = logging.getLogger(__name__)
LoggingUndefined = make_logging_undefined(
logger=logger,
base=Undefined
)
.. versionadded:: 2.8
:param logger: the logger to use. If not provided, a default logger
is created.
:param base: the base class to add logging functionality to. This
defaults to :class:`Undefined`.
"""
if logger is None:
import logging
logger = logging.getLogger(__name__)
logger.addHandler(logging.StreamHandler(sys.stderr))
def _log_message(undef: Undefined) -> None:
logger.warning( # type: ignore
"Template variable warning: %s", undef._undefined_message
)
class LoggingUndefined(base): # type: ignore
__slots__ = ()
def _fail_with_undefined_error( # type: ignore
self, *args: t.Any, **kwargs: t.Any
) -> "te.NoReturn":
try:
super()._fail_with_undefined_error(*args, **kwargs)
except self._undefined_exception as e:
logger.error("Template variable error: %s", e) # type: ignore
raise e
def __str__(self) -> str:
_log_message(self)
return super().__str__() # type: ignore
def __iter__(self) -> t.Iterator[t.Any]:
_log_message(self)
return super().__iter__() # type: ignore
def __bool__(self) -> bool:
_log_message(self)
return super().__bool__() # type: ignore
return LoggingUndefined
class ChainableUndefined(Undefined):
"""An undefined that is chainable, where both ``__getattr__`` and
``__getitem__`` return itself rather than raising an
:exc:`UndefinedError`.
>>> foo = ChainableUndefined(name='foo')
>>> str(foo.bar['baz'])
''
>>> foo.bar['baz'] + 42
Traceback (most recent call last):
...
jinja2.exceptions.UndefinedError: 'foo' is undefined
.. versionadded:: 2.11.0
"""
__slots__ = ()
def __html__(self) -> str:
return str(self)
def __getattr__(self, _: str) -> "ChainableUndefined":
return self
__getitem__ = __getattr__ # type: ignore
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):
...
jinja2.exceptions.UndefinedError: 'foo' is undefined
"""
__slots__ = ()
def __str__(self) -> str:
if self._undefined_hint:
message = f"undefined value printed: {self._undefined_hint}"
elif self._undefined_obj is missing:
message = self._undefined_name # type: ignore
else:
message = (
f"no such element: {object_type_repr(self._undefined_obj)}"
f"[{self._undefined_name!r}]"
)
return f"{{{{ {message} }}}}"
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):
...
jinja2.exceptions.UndefinedError: 'foo' is undefined
>>> not foo
Traceback (most recent call last):
...
jinja2.exceptions.UndefinedError: 'foo' is undefined
>>> foo + 42
Traceback (most recent call last):
...
jinja2.exceptions.UndefinedError: 'foo' is undefined
"""
__slots__ = ()
__iter__ = __str__ = __len__ = Undefined._fail_with_undefined_error
__eq__ = __ne__ = __bool__ = __hash__ = Undefined._fail_with_undefined_error
__contains__ = Undefined._fail_with_undefined_error
# Remove slots attributes, after the metaclass is applied they are
# unneeded and contain wrong data for subclasses.
del (
Undefined.__slots__,
ChainableUndefined.__slots__,
DebugUndefined.__slots__,
StrictUndefined.__slots__,
)
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