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Diffstat (limited to 'python/jinja2/runtime.py')
| -rw-r--r-- | python/jinja2/runtime.py | 813 |
1 files changed, 813 insertions, 0 deletions
diff --git a/python/jinja2/runtime.py b/python/jinja2/runtime.py new file mode 100644 index 0000000..f9d7a68 --- /dev/null +++ b/python/jinja2/runtime.py @@ -0,0 +1,813 @@ +# -*- coding: utf-8 -*- +""" + jinja2.runtime + ~~~~~~~~~~~~~~ + + Runtime helpers. + + :copyright: (c) 2017 by the Jinja Team. + :license: BSD. +""" +import sys + +from itertools import chain +from types import MethodType + +from jinja2.nodes import EvalContext, _context_function_types +from jinja2.utils import Markup, soft_unicode, escape, missing, concat, \ + internalcode, object_type_repr, evalcontextfunction, Namespace +from jinja2.exceptions import UndefinedError, TemplateRuntimeError, \ + TemplateNotFound +from jinja2._compat import imap, text_type, iteritems, \ + implements_iterator, implements_to_string, string_types, PY2, \ + with_metaclass + + +# these variables are exported to the template runtime +__all__ = ['LoopContext', 'TemplateReference', 'Macro', 'Markup', + 'TemplateRuntimeError', 'missing', 'concat', 'escape', + 'markup_join', 'unicode_join', 'to_string', 'identity', + 'TemplateNotFound', 'Namespace'] + +#: 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 + +#: the identity function. Useful for certain things in the environment +identity = lambda x: x + +_first_iteration = object() +_last_iteration = object() + + +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 to 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__(cls, name, bases, d): + rv = type.__new__(cls, 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): + """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__'): + fn = __obj.__call__ + for fn_type in ('contextfunction', + 'evalcontextfunction', + 'environmentfunction'): + if hasattr(fn, fn_type): + __obj = fn + break + + if isinstance(__obj, _context_function_types): + if getattr(__obj, 'contextfunction', 0): + args = (__self,) + args + elif getattr(__obj, 'evalcontextfunction', 0): + args = (__self.eval_ctx,) + args + elif getattr(__obj, 'environmentfunction', 0): + 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): + proxy = lambda self: getattr(self.get_all(), meth)() + proxy.__doc__ = getattr(dict, meth).__doc__ + proxy.__name__ = meth + return proxy + + keys = _all('keys') + values = _all('values') + items = _all('items') + + # 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 + ) + + +# register the context as mapping if possible +try: + from collections import Mapping + Mapping.register(Context) +except ImportError: + pass + + +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 + + +class LoopContextBase(object): + """A loop context for dynamic iteration.""" + + _before = _first_iteration + _current = _first_iteration + _after = _last_iteration + _length = None + + def __init__(self, undefined, recurse=None, depth0=0): + self._undefined = undefined + self._recurse = recurse + self.index0 = -1 + self.depth0 = depth0 + self._last_checked_value = missing + + def cycle(self, *args): + """Cycles among the arguments with the current loop index.""" + if not args: + raise TypeError('no items for cycling given') + return args[self.index0 % len(args)] + + def changed(self, *value): + """Checks whether the value has changed since the last call.""" + if self._last_checked_value != value: + self._last_checked_value = value + return True + return False + + first = property(lambda x: x.index0 == 0) + last = property(lambda x: x._after is _last_iteration) + index = property(lambda x: x.index0 + 1) + revindex = property(lambda x: x.length - x.index0) + revindex0 = property(lambda x: x.length - x.index) + depth = property(lambda x: x.depth0 + 1) + + @property + def previtem(self): + if self._before is _first_iteration: + return self._undefined('there is no previous item') + return self._before + + @property + def nextitem(self): + if self._after is _last_iteration: + return self._undefined('there is no next item') + return self._after + + def __len__(self): + return self.length + + @internalcode + def loop(self, iterable): + if self._recurse is None: + raise TypeError('Tried to call non recursive loop. Maybe you ' + "forgot the 'recursive' modifier.") + return self._recurse(iterable, self._recurse, self.depth0 + 1) + + # a nifty trick to enhance the error message if someone tried to call + # the the loop without or with too many arguments. + __call__ = loop + del loop + + def __repr__(self): + return '<%s %r/%r>' % ( + self.__class__.__name__, + self.index, + self.length + ) + + +class LoopContext(LoopContextBase): + + def __init__(self, iterable, undefined, recurse=None, depth0=0): + LoopContextBase.__init__(self, undefined, recurse, depth0) + self._iterator = iter(iterable) + + # try to get the length of the iterable early. This must be done + # here because there are some broken iterators around where there + # __len__ is the number of iterations left (i'm looking at your + # listreverseiterator!). + try: + self._length = len(iterable) + except (TypeError, AttributeError): + self._length = None + self._after = self._safe_next() + + @property + def length(self): + if self._length is None: + # if was not possible to get the length of the iterator when + # the loop context was created (ie: iterating over a generator) + # we have to convert the iterable into a sequence and use the + # length of that + the number of iterations so far. + iterable = tuple(self._iterator) + self._iterator = iter(iterable) + iterations_done = self.index0 + 2 + self._length = len(iterable) + iterations_done + return self._length + + def __iter__(self): + return LoopContextIterator(self) + + def _safe_next(self): + try: + return next(self._iterator) + except StopIteration: + return _last_iteration + + +@implements_iterator +class LoopContextIterator(object): + """The iterator for a loop context.""" + __slots__ = ('context',) + + def __init__(self, context): + self.context = context + + def __iter__(self): + return self + + def __next__(self): + ctx = self.context + ctx.index0 += 1 + if ctx._after is _last_iteration: + raise StopIteration() + ctx._before = ctx._current + ctx._current = ctx._after + ctx._after = ctx._safe_next() + return ctx._current, ctx + + +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 + # problemtic for macros because if a macro is safe or not not so + # much depends on the escape mode when it was defined but 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 anwyays. 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 idx, name in enumerate(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:`jinja2.exceptions.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 + + @internalcode + def _fail_with_undefined_error(self, *args, **kwargs): + """Regular callback function for undefined objects that raises an + `jinja2.exceptions.UndefinedError` on call. + """ + if self._undefined_hint is None: + if self._undefined_obj is missing: + hint = '%r is undefined' % self._undefined_name + elif not isinstance(self._undefined_name, string_types): + hint = '%s has no element %r' % ( + object_type_repr(self._undefined_obj), + self._undefined_name + ) + else: + hint = '%r has no attribute %r' % ( + object_type_repr(self._undefined_obj), + self._undefined_name + ) + else: + hint = self._undefined_hint + raise self._undefined_exception(hint) + + @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 + + +@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__, DebugUndefined.__slots__, StrictUndefined.__slots__ |