571 lines
19 KiB
Python
571 lines
19 KiB
Python
# -*- coding: utf-8 -*-
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"""
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jinja2.runtime
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~~~~~~~~~~~~~~
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Runtime helpers.
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:copyright: (c) 2010 by the Jinja Team.
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:license: BSD.
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"""
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from itertools import chain
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from jinja2.nodes import EvalContext, _context_function_types
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from jinja2.utils import Markup, soft_unicode, escape, missing, concat, \
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internalcode, object_type_repr
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from jinja2.exceptions import UndefinedError, TemplateRuntimeError, \
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TemplateNotFound
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from jinja2._compat import next, imap, text_type, iteritems, \
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implements_iterator, implements_to_string, string_types, PY2
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# these variables are exported to the template runtime
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__all__ = ['LoopContext', 'TemplateReference', 'Macro', 'Markup',
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'TemplateRuntimeError', 'missing', 'concat', 'escape',
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'markup_join', 'unicode_join', 'to_string', 'identity',
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'TemplateNotFound']
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#: the name of the function that is used to convert something into
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#: a string. We can just use the text type here.
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to_string = text_type
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#: the identity function. Useful for certain things in the environment
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identity = lambda x: x
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_last_iteration = object()
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def markup_join(seq):
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"""Concatenation that escapes if necessary and converts to unicode."""
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buf = []
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iterator = imap(soft_unicode, seq)
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for arg in iterator:
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buf.append(arg)
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if hasattr(arg, '__html__'):
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return Markup(u'').join(chain(buf, iterator))
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return concat(buf)
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def unicode_join(seq):
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"""Simple args to unicode conversion and concatenation."""
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return concat(imap(text_type, seq))
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def new_context(environment, template_name, blocks, vars=None,
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shared=None, globals=None, locals=None):
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"""Internal helper to for context creation."""
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if vars is None:
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vars = {}
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if shared:
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parent = vars
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else:
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parent = dict(globals or (), **vars)
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if locals:
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# if the parent is shared a copy should be created because
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# we don't want to modify the dict passed
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if shared:
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parent = dict(parent)
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for key, value in iteritems(locals):
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if key[:2] == 'l_' and value is not missing:
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parent[key[2:]] = value
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return Context(environment, parent, template_name, blocks)
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class TemplateReference(object):
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"""The `self` in templates."""
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def __init__(self, context):
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self.__context = context
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def __getitem__(self, name):
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blocks = self.__context.blocks[name]
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return BlockReference(name, self.__context, blocks, 0)
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def __repr__(self):
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return '<%s %r>' % (
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self.__class__.__name__,
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self.__context.name
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)
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class Context(object):
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"""The template context holds the variables of a template. It stores the
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values passed to the template and also the names the template exports.
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Creating instances is neither supported nor useful as it's created
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automatically at various stages of the template evaluation and should not
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be created by hand.
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The context is immutable. Modifications on :attr:`parent` **must not**
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happen and modifications on :attr:`vars` are allowed from generated
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template code only. Template filters and global functions marked as
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:func:`contextfunction`\s get the active context passed as first argument
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and are allowed to access the context read-only.
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The template context supports read only dict operations (`get`,
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`keys`, `values`, `items`, `iterkeys`, `itervalues`, `iteritems`,
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`__getitem__`, `__contains__`). Additionally there is a :meth:`resolve`
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method that doesn't fail with a `KeyError` but returns an
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:class:`Undefined` object for missing variables.
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"""
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__slots__ = ('parent', 'vars', 'environment', 'eval_ctx', 'exported_vars',
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'name', 'blocks', '__weakref__')
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def __init__(self, environment, parent, name, blocks):
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self.parent = parent
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self.vars = {}
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self.environment = environment
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self.eval_ctx = EvalContext(self.environment, name)
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self.exported_vars = set()
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self.name = name
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# create the initial mapping of blocks. Whenever template inheritance
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# takes place the runtime will update this mapping with the new blocks
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# from the template.
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self.blocks = dict((k, [v]) for k, v in iteritems(blocks))
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def super(self, name, current):
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"""Render a parent block."""
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try:
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blocks = self.blocks[name]
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index = blocks.index(current) + 1
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blocks[index]
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except LookupError:
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return self.environment.undefined('there is no parent block '
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'called %r.' % name,
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name='super')
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return BlockReference(name, self, blocks, index)
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def get(self, key, default=None):
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"""Returns an item from the template context, if it doesn't exist
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`default` is returned.
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"""
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try:
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return self[key]
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except KeyError:
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return default
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def resolve(self, key):
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"""Looks up a variable like `__getitem__` or `get` but returns an
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:class:`Undefined` object with the name of the name looked up.
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"""
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if key in self.vars:
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return self.vars[key]
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if key in self.parent:
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return self.parent[key]
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return self.environment.undefined(name=key)
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def get_exported(self):
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"""Get a new dict with the exported variables."""
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return dict((k, self.vars[k]) for k in self.exported_vars)
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def get_all(self):
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"""Return a copy of the complete context as dict including the
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exported variables.
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"""
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return dict(self.parent, **self.vars)
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@internalcode
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def call(__self, __obj, *args, **kwargs):
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"""Call the callable with the arguments and keyword arguments
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provided but inject the active context or environment as first
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argument if the callable is a :func:`contextfunction` or
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:func:`environmentfunction`.
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"""
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if __debug__:
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__traceback_hide__ = True
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# Allow callable classes to take a context
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fn = __obj.__call__
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for fn_type in ('contextfunction',
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'evalcontextfunction',
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'environmentfunction'):
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if hasattr(fn, fn_type):
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__obj = fn
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break
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if isinstance(__obj, _context_function_types):
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if getattr(__obj, 'contextfunction', 0):
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args = (__self,) + args
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elif getattr(__obj, 'evalcontextfunction', 0):
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args = (__self.eval_ctx,) + args
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elif getattr(__obj, 'environmentfunction', 0):
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args = (__self.environment,) + args
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try:
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return __obj(*args, **kwargs)
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except StopIteration:
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return __self.environment.undefined('value was undefined because '
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'a callable raised a '
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'StopIteration exception')
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def derived(self, locals=None):
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"""Internal helper function to create a derived context."""
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context = new_context(self.environment, self.name, {},
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self.parent, True, None, locals)
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context.vars.update(self.vars)
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context.eval_ctx = self.eval_ctx
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context.blocks.update((k, list(v)) for k, v in iteritems(self.blocks))
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return context
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def _all(meth):
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proxy = lambda self: getattr(self.get_all(), meth)()
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proxy.__doc__ = getattr(dict, meth).__doc__
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proxy.__name__ = meth
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return proxy
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keys = _all('keys')
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values = _all('values')
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items = _all('items')
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# not available on python 3
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if PY2:
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iterkeys = _all('iterkeys')
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itervalues = _all('itervalues')
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iteritems = _all('iteritems')
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del _all
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def __contains__(self, name):
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return name in self.vars or name in self.parent
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def __getitem__(self, key):
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"""Lookup a variable or raise `KeyError` if the variable is
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undefined.
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"""
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item = self.resolve(key)
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if isinstance(item, Undefined):
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raise KeyError(key)
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return item
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def __repr__(self):
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return '<%s %s of %r>' % (
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self.__class__.__name__,
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repr(self.get_all()),
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self.name
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)
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# register the context as mapping if possible
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try:
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from collections import Mapping
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Mapping.register(Context)
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except ImportError:
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pass
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class BlockReference(object):
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"""One block on a template reference."""
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def __init__(self, name, context, stack, depth):
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self.name = name
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self._context = context
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self._stack = stack
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self._depth = depth
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@property
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def super(self):
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"""Super the block."""
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if self._depth + 1 >= len(self._stack):
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return self._context.environment. \
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undefined('there is no parent block called %r.' %
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self.name, name='super')
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return BlockReference(self.name, self._context, self._stack,
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self._depth + 1)
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@internalcode
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def __call__(self):
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rv = concat(self._stack[self._depth](self._context))
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if self._context.eval_ctx.autoescape:
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rv = Markup(rv)
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return rv
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class LoopContext(object):
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"""A loop context for dynamic iteration."""
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def __init__(self, iterable, recurse=None, depth0=0):
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self._iterator = iter(iterable)
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self._recurse = recurse
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self._after = self._safe_next()
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self.index0 = -1
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self.depth0 = depth0
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# try to get the length of the iterable early. This must be done
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# here because there are some broken iterators around where there
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# __len__ is the number of iterations left (i'm looking at your
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# listreverseiterator!).
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try:
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self._length = len(iterable)
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except (TypeError, AttributeError):
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self._length = None
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def cycle(self, *args):
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"""Cycles among the arguments with the current loop index."""
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if not args:
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raise TypeError('no items for cycling given')
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return args[self.index0 % len(args)]
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first = property(lambda x: x.index0 == 0)
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last = property(lambda x: x._after is _last_iteration)
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index = property(lambda x: x.index0 + 1)
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revindex = property(lambda x: x.length - x.index0)
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revindex0 = property(lambda x: x.length - x.index)
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depth = property(lambda x: x.depth0 + 1)
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def __len__(self):
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return self.length
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def __iter__(self):
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return LoopContextIterator(self)
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def _safe_next(self):
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try:
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return next(self._iterator)
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except StopIteration:
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return _last_iteration
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@internalcode
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def loop(self, iterable):
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if self._recurse is None:
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raise TypeError('Tried to call non recursive loop. Maybe you '
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"forgot the 'recursive' modifier.")
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return self._recurse(iterable, self._recurse, self.depth0 + 1)
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# a nifty trick to enhance the error message if someone tried to call
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# the the loop without or with too many arguments.
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__call__ = loop
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del loop
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@property
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def length(self):
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if self._length is None:
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# if was not possible to get the length of the iterator when
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# the loop context was created (ie: iterating over a generator)
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# we have to convert the iterable into a sequence and use the
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# length of that.
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iterable = tuple(self._iterator)
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self._iterator = iter(iterable)
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self._length = len(iterable) + self.index0 + 1
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return self._length
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def __repr__(self):
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return '<%s %r/%r>' % (
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self.__class__.__name__,
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self.index,
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self.length
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)
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@implements_iterator
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class LoopContextIterator(object):
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"""The iterator for a loop context."""
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__slots__ = ('context',)
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def __init__(self, context):
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self.context = context
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def __iter__(self):
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return self
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def __next__(self):
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ctx = self.context
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ctx.index0 += 1
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if ctx._after is _last_iteration:
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raise StopIteration()
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next_elem = ctx._after
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ctx._after = ctx._safe_next()
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return next_elem, ctx
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class Macro(object):
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"""Wraps a macro function."""
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def __init__(self, environment, func, name, arguments, defaults,
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catch_kwargs, catch_varargs, caller):
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self._environment = environment
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self._func = func
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self._argument_count = len(arguments)
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self.name = name
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self.arguments = arguments
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self.defaults = defaults
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self.catch_kwargs = catch_kwargs
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self.catch_varargs = catch_varargs
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self.caller = caller
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@internalcode
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def __call__(self, *args, **kwargs):
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# try to consume the positional arguments
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arguments = list(args[:self._argument_count])
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off = len(arguments)
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# if the number of arguments consumed is not the number of
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# arguments expected we start filling in keyword arguments
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# and defaults.
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if off != self._argument_count:
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for idx, name in enumerate(self.arguments[len(arguments):]):
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try:
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value = kwargs.pop(name)
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except KeyError:
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try:
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value = self.defaults[idx - self._argument_count + off]
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except IndexError:
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value = self._environment.undefined(
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'parameter %r was not provided' % name, name=name)
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arguments.append(value)
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# it's important that the order of these arguments does not change
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# if not also changed in the compiler's `function_scoping` method.
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# the order is caller, keyword arguments, positional arguments!
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if self.caller:
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caller = kwargs.pop('caller', None)
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if caller is None:
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caller = self._environment.undefined('No caller defined',
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name='caller')
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arguments.append(caller)
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if self.catch_kwargs:
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arguments.append(kwargs)
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elif kwargs:
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raise TypeError('macro %r takes no keyword argument %r' %
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(self.name, next(iter(kwargs))))
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if self.catch_varargs:
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arguments.append(args[self._argument_count:])
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elif len(args) > self._argument_count:
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raise TypeError('macro %r takes not more than %d argument(s)' %
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(self.name, len(self.arguments)))
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return self._func(*arguments)
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def __repr__(self):
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return '<%s %s>' % (
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self.__class__.__name__,
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self.name is None and 'anonymous' or repr(self.name)
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)
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@implements_to_string
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class Undefined(object):
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"""The default undefined type. This undefined type can be printed and
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iterated over, but every other access will raise an :exc:`UndefinedError`:
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>>> foo = Undefined(name='foo')
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>>> str(foo)
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''
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>>> not foo
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True
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>>> foo + 42
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Traceback (most recent call last):
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...
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UndefinedError: 'foo' is undefined
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"""
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__slots__ = ('_undefined_hint', '_undefined_obj', '_undefined_name',
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'_undefined_exception')
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def __init__(self, hint=None, obj=missing, name=None, exc=UndefinedError):
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self._undefined_hint = hint
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self._undefined_obj = obj
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self._undefined_name = name
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self._undefined_exception = exc
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@internalcode
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def _fail_with_undefined_error(self, *args, **kwargs):
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"""Regular callback function for undefined objects that raises an
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`UndefinedError` on call.
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"""
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if self._undefined_hint is None:
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if self._undefined_obj is missing:
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hint = '%r is undefined' % self._undefined_name
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elif not isinstance(self._undefined_name, string_types):
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hint = '%s has no element %r' % (
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object_type_repr(self._undefined_obj),
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self._undefined_name
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)
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else:
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hint = '%r has no attribute %r' % (
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object_type_repr(self._undefined_obj),
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self._undefined_name
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)
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else:
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hint = self._undefined_hint
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raise self._undefined_exception(hint)
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@internalcode
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def __getattr__(self, name):
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if name[:2] == '__':
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raise AttributeError(name)
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return self._fail_with_undefined_error()
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__add__ = __radd__ = __mul__ = __rmul__ = __div__ = __rdiv__ = \
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__truediv__ = __rtruediv__ = __floordiv__ = __rfloordiv__ = \
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__mod__ = __rmod__ = __pos__ = __neg__ = __call__ = \
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__getitem__ = __lt__ = __le__ = __gt__ = __ge__ = __int__ = \
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__float__ = __complex__ = __pow__ = __rpow__ = \
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_fail_with_undefined_error
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def __str__(self):
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return u''
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def __len__(self):
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return 0
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def __iter__(self):
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if 0:
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yield None
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def __nonzero__(self):
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return False
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def __repr__(self):
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return 'Undefined'
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@implements_to_string
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class DebugUndefined(Undefined):
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"""An undefined that returns the debug info when printed.
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>>> foo = DebugUndefined(name='foo')
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>>> str(foo)
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'{{ foo }}'
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>>> not foo
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True
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>>> foo + 42
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Traceback (most recent call last):
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...
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UndefinedError: 'foo' is undefined
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"""
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__slots__ = ()
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def __str__(self):
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if self._undefined_hint is None:
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if self._undefined_obj is missing:
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return u'{{ %s }}' % self._undefined_name
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return '{{ no such element: %s[%r] }}' % (
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object_type_repr(self._undefined_obj),
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self._undefined_name
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)
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return u'{{ undefined value printed: %s }}' % self._undefined_hint
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@implements_to_string
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class StrictUndefined(Undefined):
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"""An undefined that barks on print and iteration as well as boolean
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tests and all kinds of comparisons. In other words: you can do nothing
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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__ = 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__
|