# -*- coding: utf-8 -*- """The runtime functions and state used by compiled templates.""" import sys from itertools import chain from types import MethodType from markupsafe import escape # noqa: F401 from markupsafe import Markup from markupsafe import soft_unicode from ._compat import abc from ._compat import imap from ._compat import implements_iterator from ._compat import implements_to_string from ._compat import iteritems from ._compat import PY2 from ._compat import string_types from ._compat import text_type from ._compat import with_metaclass from .exceptions import TemplateNotFound # noqa: F401 from .exceptions import TemplateRuntimeError # noqa: F401 from .exceptions import UndefinedError from .nodes import EvalContext from .utils import concat from .utils import evalcontextfunction from .utils import internalcode from .utils import missing from .utils import Namespace # noqa: F401 from .utils import object_type_repr # these variables are exported to the template runtime exported = [ "LoopContext", "TemplateReference", "Macro", "Markup", "TemplateRuntimeError", "missing", "concat", "escape", "markup_join", "unicode_join", "to_string", "identity", "TemplateNotFound", "Namespace", "Undefined", ] #: the name of the function that is used to convert something into #: a string. We can just use the text type here. to_string = text_type def identity(x): """Returns its argument. Useful for certain things in the environment. """ return x def markup_join(seq): """Concatenation that escapes if necessary and converts to unicode.""" buf = [] iterator = imap(soft_unicode, seq) for arg in iterator: buf.append(arg) if hasattr(arg, "__html__"): return Markup(u"").join(chain(buf, iterator)) return concat(buf) def unicode_join(seq): """Simple args to unicode conversion and concatenation.""" return concat(imap(text_type, seq)) def new_context( environment, template_name, blocks, vars=None, shared=None, globals=None, locals=None, ): """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 iteritems(locals): if value is not missing: parent[key] = value return environment.context_class(environment, parent, template_name, blocks) class TemplateReference(object): """The `self` in templates.""" def __init__(self, context): self.__context = context def __getitem__(self, name): blocks = self.__context.blocks[name] return BlockReference(name, self.__context, blocks, 0) def __repr__(self): return "<%s %r>" % (self.__class__.__name__, self.__context.name) def _get_func(x): return getattr(x, "__func__", x) class ContextMeta(type): def __new__(mcs, name, bases, d): rv = type.__new__(mcs, name, bases, d) if bases == (): return rv resolve = _get_func(rv.resolve) default_resolve = _get_func(Context.resolve) resolve_or_missing = _get_func(rv.resolve_or_missing) default_resolve_or_missing = _get_func(Context.resolve_or_missing) # If we have a changed resolve but no changed default or missing # resolve we invert the call logic. if ( resolve is not default_resolve and resolve_or_missing is default_resolve_or_missing ): rv._legacy_resolve_mode = True elif ( resolve is default_resolve and resolve_or_missing is default_resolve_or_missing ): rv._fast_resolve_mode = True return rv def resolve_or_missing(context, key, missing=missing): if key in context.vars: return context.vars[key] if key in context.parent: return context.parent[key] return missing class Context(with_metaclass(ContextMeta)): """The template context holds the variables of a template. It stores the values passed to the template and also the names the template exports. Creating instances is neither supported nor useful as it's created automatically at various stages of the template evaluation and should not be created by hand. The context is immutable. Modifications on :attr:`parent` **must not** happen and modifications on :attr:`vars` are allowed from generated template code only. Template filters and global functions marked as :func:`contextfunction`\\s get the active context passed as first argument and are allowed to access the context read-only. The template context supports read only dict operations (`get`, `keys`, `values`, `items`, `iterkeys`, `itervalues`, `iteritems`, `__getitem__`, `__contains__`). Additionally there is a :meth:`resolve` method that doesn't fail with a `KeyError` but returns an :class:`Undefined` object for missing variables. """ # XXX: we want to eventually make this be a deprecation warning and # remove it. _legacy_resolve_mode = False _fast_resolve_mode = False def __init__(self, environment, parent, name, blocks): self.parent = parent self.vars = {} self.environment = environment self.eval_ctx = EvalContext(self.environment, name) self.exported_vars = set() self.name = name # create the initial mapping of blocks. Whenever template inheritance # takes place the runtime will update this mapping with the new blocks # from the template. self.blocks = dict((k, [v]) for k, v in iteritems(blocks)) # In case we detect the fast resolve mode we can set up an alias # here that bypasses the legacy code logic. if self._fast_resolve_mode: self.resolve_or_missing = MethodType(resolve_or_missing, self) def super(self, name, current): """Render a parent block.""" try: blocks = self.blocks[name] index = blocks.index(current) + 1 blocks[index] except LookupError: return self.environment.undefined( "there is no parent block called %r." % name, name="super" ) return BlockReference(name, self, blocks, index) def get(self, key, default=None): """Returns an item from the template context, if it doesn't exist `default` is returned. """ try: return self[key] except KeyError: return default def resolve(self, key): """Looks up a variable like `__getitem__` or `get` but returns an :class:`Undefined` object with the name of the name looked up. """ if self._legacy_resolve_mode: rv = resolve_or_missing(self, key) else: rv = self.resolve_or_missing(key) if rv is missing: return self.environment.undefined(name=key) return rv def resolve_or_missing(self, key): """Resolves a variable like :meth:`resolve` but returns the special `missing` value if it cannot be found. """ if self._legacy_resolve_mode: rv = self.resolve(key) if isinstance(rv, Undefined): rv = missing return rv return resolve_or_missing(self, key) def get_exported(self): """Get a new dict with the exported variables.""" return dict((k, self.vars[k]) for k in self.exported_vars) def get_all(self): """Return 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, *args, **kwargs): # noqa: B902 """Call the callable with the arguments and keyword arguments provided but inject the active context or environment as first argument if the callable is a :func:`contextfunction` or :func:`environmentfunction`. """ if __debug__: __traceback_hide__ = True # noqa # Allow callable classes to take a context if hasattr(__obj, "__call__"): # noqa: B004 fn = __obj.__call__ for fn_type in ( "contextfunction", "evalcontextfunction", "environmentfunction", ): if hasattr(fn, fn_type): __obj = fn break if callable(__obj): if getattr(__obj, "contextfunction", False) is True: args = (__self,) + args elif getattr(__obj, "evalcontextfunction", False) is True: args = (__self.eval_ctx,) + args elif getattr(__obj, "environmentfunction", False) is True: args = (__self.environment,) + args 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=None): """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 iteritems(self.blocks)) return context def _all(meth): # noqa: B902 def proxy(self): return getattr(self.get_all(), meth)() proxy.__doc__ = getattr(dict, meth).__doc__ proxy.__name__ = meth return proxy keys = _all("keys") values = _all("values") items = _all("items") # not available on python 3 if PY2: iterkeys = _all("iterkeys") itervalues = _all("itervalues") iteritems = _all("iteritems") del _all def __contains__(self, name): return name in self.vars or name in self.parent def __getitem__(self, key): """Lookup a variable or raise `KeyError` if the variable is undefined. """ item = self.resolve_or_missing(key) if item is missing: raise KeyError(key) return item def __repr__(self): return "<%s %s of %r>" % ( self.__class__.__name__, repr(self.get_all()), self.name, ) abc.Mapping.register(Context) class BlockReference(object): """One block on a template reference.""" def __init__(self, name, context, stack, depth): self.name = name self._context = context self._stack = stack self._depth = depth @property def super(self): """Super the block.""" if self._depth + 1 >= len(self._stack): return self._context.environment.undefined( "there is no parent block called %r." % self.name, name="super" ) return BlockReference(self.name, self._context, self._stack, self._depth + 1) @internalcode def __call__(self): rv = concat(self._stack[self._depth](self._context)) if self._context.eval_ctx.autoescape: rv = Markup(rv) return rv @implements_iterator 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 = None _after = missing _current = missing _before = missing _last_changed_value = missing def __init__(self, iterable, undefined, recurse=None, depth0=0): """ :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): return iter(iterable) @property def length(self): """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) 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): return self.length @property def depth(self): """How many levels deep a recursive loop currently is, starting at 1.""" return self.depth0 + 1 @property def index(self): """Current iteration of the loop, starting at 1.""" return self.index0 + 1 @property def revindex0(self): """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): """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): """Whether this is the first iteration of the loop.""" return self.index0 == 0 def _peek_next(self): """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): """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): """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): """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:`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): """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): """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): return self def __next__(self): 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): """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): return "<%s %d/%d>" % (self.__class__.__name__, self.index, self.length) class Macro(object): """Wraps a macro function.""" def __init__( self, environment, func, name, arguments, catch_kwargs, catch_varargs, caller, default_autoescape=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: default_autoescape = environment.autoescape self._default_autoescape = default_autoescape @internalcode @evalcontextfunction def __call__(self, *args, **kwargs): # 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( "macro %r was invoked with two values for " "the special caller argument. This is " "most likely a bug." % self.name ) raise TypeError( "macro %r takes no keyword argument %r" % (self.name, next(iter(kwargs))) ) if self.catch_varargs: arguments.append(args[self._argument_count :]) elif len(args) > self._argument_count: raise TypeError( "macro %r takes not more than %d argument(s)" % (self.name, len(self.arguments)) ) return self._invoke(arguments, autoescape) def _invoke(self, arguments, autoescape): """This method is being swapped out by the async implementation.""" rv = self._func(*arguments) if autoescape: rv = Markup(rv) return rv def __repr__(self): return "<%s %s>" % ( self.__class__.__name__, self.name is None and "anonymous" or repr(self.name), ) @implements_to_string class Undefined(object): """The default undefined type. This undefined type can be printed and iterated over, but every other access will raise an :exc:`UndefinedError`: >>> foo = Undefined(name='foo') >>> str(foo) '' >>> not foo True >>> foo + 42 Traceback (most recent call last): ... jinja2.exceptions.UndefinedError: 'foo' is undefined """ __slots__ = ( "_undefined_hint", "_undefined_obj", "_undefined_name", "_undefined_exception", ) def __init__(self, hint=None, obj=missing, name=None, exc=UndefinedError): self._undefined_hint = hint self._undefined_obj = obj self._undefined_name = name self._undefined_exception = exc @property def _undefined_message(self): """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 "%r is undefined" % self._undefined_name if not isinstance(self._undefined_name, string_types): return "%s has no element %r" % ( object_type_repr(self._undefined_obj), self._undefined_name, ) return "%r has no attribute %r" % ( object_type_repr(self._undefined_obj), self._undefined_name, ) @internalcode def _fail_with_undefined_error(self, *args, **kwargs): """Raise an :exc:`UndefinedError` when operations are performed on the undefined value. """ raise self._undefined_exception(self._undefined_message) @internalcode def __getattr__(self, name): if name[:2] == "__": raise AttributeError(name) return self._fail_with_undefined_error() __add__ = ( __radd__ ) = ( __mul__ ) = ( __rmul__ ) = ( __div__ ) = ( __rdiv__ ) = ( __truediv__ ) = ( __rtruediv__ ) = ( __floordiv__ ) = ( __rfloordiv__ ) = ( __mod__ ) = ( __rmod__ ) = ( __pos__ ) = ( __neg__ ) = ( __call__ ) = ( __getitem__ ) = ( __lt__ ) = ( __le__ ) = ( __gt__ ) = ( __ge__ ) = ( __int__ ) = ( __float__ ) = ( __complex__ ) = __pow__ = __rpow__ = __sub__ = __rsub__ = _fail_with_undefined_error def __eq__(self, other): return type(self) is type(other) def __ne__(self, other): return not self.__eq__(other) def __hash__(self): return id(type(self)) def __str__(self): return u"" def __len__(self): return 0 def __iter__(self): if 0: yield None def __nonzero__(self): return False __bool__ = __nonzero__ def __repr__(self): return "Undefined" def make_logging_undefined(logger=None, base=None): """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)) if base is None: base = Undefined def _log_message(undef): if undef._undefined_hint is None: if undef._undefined_obj is missing: hint = "%s is undefined" % undef._undefined_name elif not isinstance(undef._undefined_name, string_types): hint = "%s has no element %s" % ( object_type_repr(undef._undefined_obj), undef._undefined_name, ) else: hint = "%s has no attribute %s" % ( object_type_repr(undef._undefined_obj), undef._undefined_name, ) else: hint = undef._undefined_hint logger.warning("Template variable warning: %s", hint) class LoggingUndefined(base): def _fail_with_undefined_error(self, *args, **kwargs): try: return base._fail_with_undefined_error(self, *args, **kwargs) except self._undefined_exception as e: logger.error("Template variable error: %s", str(e)) raise e def __str__(self): rv = base.__str__(self) _log_message(self) return rv def __iter__(self): rv = base.__iter__(self) _log_message(self) return rv if PY2: def __nonzero__(self): rv = base.__nonzero__(self) _log_message(self) return rv def __unicode__(self): rv = base.__unicode__(self) _log_message(self) return rv else: def __bool__(self): rv = base.__bool__(self) _log_message(self) return rv return LoggingUndefined # No @implements_to_string decorator here because __str__ # is not overwritten from Undefined in this class. # This would cause a recursion error in Python 2. 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): return self.__str__() def __getattr__(self, _): return self __getitem__ = __getattr__ @implements_to_string 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): if self._undefined_hint is None: if self._undefined_obj is missing: return u"{{ %s }}" % self._undefined_name return "{{ no such element: %s[%r] }}" % ( object_type_repr(self._undefined_obj), self._undefined_name, ) return u"{{ undefined value printed: %s }}" % self._undefined_hint @implements_to_string 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__ ) = ( __nonzero__ ) = __eq__ = __ne__ = __bool__ = __hash__ = Undefined._fail_with_undefined_error # remove remaining slots attributes, after the metaclass did the magic they # are unneeded and irritating as they contain wrong data for the subclasses. del ( Undefined.__slots__, ChainableUndefined.__slots__, DebugUndefined.__slots__, StrictUndefined.__slots__, )