blob: 7791c645afe997d45e75355fddad384f9d525d94 [file] [log] [blame]
# -*- coding: utf-8 -*-
Runtime helpers.
:copyright: (c) 2010 by the Jinja Team.
:license: BSD.
from itertools import chain
from jinja2.nodes import EvalContext, _context_function_types
from jinja2.utils import Markup, soft_unicode, escape, missing, concat, \
internalcode, object_type_repr
from jinja2.exceptions import UndefinedError, TemplateRuntimeError, \
from jinja2._compat import next, imap, text_type, iteritems, \
implements_iterator, implements_to_string, string_types, PY2
# these variables are exported to the template runtime
__all__ = ['LoopContext', 'TemplateReference', 'Macro', 'Markup',
'TemplateRuntimeError', 'missing', 'concat', 'escape',
'markup_join', 'unicode_join', 'to_string', 'identity',
#: 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
_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:
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
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 key[:2] == 'l_' and value is not missing:
parent[key[2:]] = value
return Context(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>' % (
class Context(object):
"""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.
__slots__ = ('parent', 'vars', 'environment', 'eval_ctx', 'exported_vars',
'name', 'blocks', '__weakref__')
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() = 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))
def super(self, name, current):
"""Render a parent block."""
blocks = self.blocks[name]
index = blocks.index(current) + 1
except LookupError:
return self.environment.undefined('there is no parent block '
'called %r.' % name,
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.
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 key in self.vars:
return self.vars[key]
if key in self.parent:
return self.parent[key]
return self.environment.undefined(name=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 a copy of the complete context as dict including the
exported variables.
return dict(self.parent, **self.vars)
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
if __debug__:
__traceback_hide__ = True
# Allow callable classes to take a context
fn = __obj.__call__
for fn_type in ('contextfunction',
if hasattr(fn, fn_type):
__obj = fn
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
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."""
context = new_context(self.environment,, {},
self.parent, 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
item = self.resolve(key)
if isinstance(item, Undefined):
raise KeyError(key)
return item
def __repr__(self):
return '<%s %s of %r>' % (
# register the context as mapping if possible
from collections import Mapping
except ImportError:
class BlockReference(object):
"""One block on a template reference."""
def __init__(self, name, context, stack, depth): = name
self._context = context
self._stack = stack
self._depth = depth
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.' %, name='super')
return BlockReference(, self._context, self._stack,
self._depth + 1)
def __call__(self):
rv = concat(self._stack[self._depth](self._context))
if self._context.eval_ctx.autoescape:
rv = Markup(rv)
return rv
class LoopContext(object):
"""A loop context for dynamic iteration."""
def __init__(self, iterable, recurse=None, depth0=0):
self._iterator = iter(iterable)
self._recurse = recurse
self._after = self._safe_next()
self.index0 = -1
self.depth0 = depth0
# 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!).
self._length = len(iterable)
except (TypeError, AttributeError):
self._length = None
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)]
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)
def __len__(self):
return self.length
def __iter__(self):
return LoopContextIterator(self)
def _safe_next(self):
return next(self._iterator)
except StopIteration:
return _last_iteration
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 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.
iterable = tuple(self._iterator)
self._iterator = iter(iterable)
self._length = len(iterable) + self.index0 + 1
return self._length
def __repr__(self):
return '<%s %r/%r>' % (
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()
next_elem = ctx._after
ctx._after = ctx._safe_next()
return next_elem, ctx
class Macro(object):
"""Wraps a macro function."""
def __init__(self, environment, func, name, arguments, defaults,
catch_kwargs, catch_varargs, caller):
self._environment = environment
self._func = func
self._argument_count = len(arguments) = name
self.arguments = arguments
self.defaults = defaults
self.catch_kwargs = catch_kwargs
self.catch_varargs = catch_varargs
self.caller = caller
def __call__(self, *args, **kwargs):
# try to consume the positional arguments
arguments = list(args[:self._argument_count])
off = len(arguments)
# 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):]):
value = kwargs.pop(name)
except KeyError:
value = self.defaults[idx - self._argument_count + off]
except IndexError:
value = self._environment.undefined(
'parameter %r was not provided' % name, name=name)
# 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:
caller = kwargs.pop('caller', None)
if caller is None:
caller = self._environment.undefined('No caller defined',
if self.catch_kwargs:
elif kwargs:
raise TypeError('macro %r takes no keyword argument %r' %
(, next(iter(kwargs))))
if self.catch_varargs:
elif len(args) > self._argument_count:
raise TypeError('macro %r takes not more than %d argument(s)' %
(, len(self.arguments)))
return self._func(*arguments)
def __repr__(self):
return '<%s %s>' % (
self.__class__.__name__, is None and 'anonymous' or repr(
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
>>> foo + 42
Traceback (most recent call last):
UndefinedError: 'foo' is undefined
__slots__ = ('_undefined_hint', '_undefined_obj', '_undefined_name',
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
def _fail_with_undefined_error(self, *args, **kwargs):
"""Regular callback function for undefined objects that raises an
`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' % (
hint = '%r has no attribute %r' % (
hint = self._undefined_hint
raise self._undefined_exception(hint)
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__ = \
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
def __repr__(self):
return 'Undefined'
class DebugUndefined(Undefined):
"""An undefined that returns the debug info when printed.
>>> foo = DebugUndefined(name='foo')
>>> str(foo)
'{{ foo }}'
>>> not foo
>>> foo + 42
Traceback (most recent call last):
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] }}' % (
return u'{{ undefined value printed: %s }}' % self._undefined_hint
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):
UndefinedError: 'foo' is undefined
>>> not foo
Traceback (most recent call last):
UndefinedError: 'foo' is undefined
>>> foo + 42
Traceback (most recent call last):
UndefinedError: 'foo' is undefined
__slots__ = ()
__iter__ = __str__ = __len__ = __nonzero__ = __eq__ = \
__ne__ = __bool__ = __hash__ = \
# 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__