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1 # -*- coding: utf-8 -*- | |
2 """ | |
3 jinja2.runtime | |
4 ~~~~~~~~~~~~~~ | |
5 | |
6 Runtime helpers. | |
7 | |
8 :copyright: (c) 2010 by the Jinja Team. | |
9 :license: BSD. | |
10 """ | |
11 from itertools import chain | |
12 from jinja2.nodes import EvalContext, _context_function_types | |
13 from jinja2.utils import Markup, soft_unicode, escape, missing, concat, \ | |
14 internalcode, object_type_repr | |
15 from jinja2.exceptions import UndefinedError, TemplateRuntimeError, \ | |
16 TemplateNotFound | |
17 from jinja2._compat import next, imap, text_type, iteritems, \ | |
18 implements_iterator, implements_to_string, string_types, PY2 | |
19 | |
20 | |
21 # these variables are exported to the template runtime | |
22 __all__ = ['LoopContext', 'TemplateReference', 'Macro', 'Markup', | |
23 'TemplateRuntimeError', 'missing', 'concat', 'escape', | |
24 'markup_join', 'unicode_join', 'to_string', 'identity', | |
25 'TemplateNotFound'] | |
26 | |
27 #: the name of the function that is used to convert something into | |
28 #: a string. We can just use the text type here. | |
29 to_string = text_type | |
30 | |
31 #: the identity function. Useful for certain things in the environment | |
32 identity = lambda x: x | |
33 | |
34 _last_iteration = object() | |
35 | |
36 | |
37 def markup_join(seq): | |
38 """Concatenation that escapes if necessary and converts to unicode.""" | |
39 buf = [] | |
40 iterator = imap(soft_unicode, seq) | |
41 for arg in iterator: | |
42 buf.append(arg) | |
43 if hasattr(arg, '__html__'): | |
44 return Markup(u'').join(chain(buf, iterator)) | |
45 return concat(buf) | |
46 | |
47 | |
48 def unicode_join(seq): | |
49 """Simple args to unicode conversion and concatenation.""" | |
50 return concat(imap(text_type, seq)) | |
51 | |
52 | |
53 def new_context(environment, template_name, blocks, vars=None, | |
54 shared=None, globals=None, locals=None): | |
55 """Internal helper to for context creation.""" | |
56 if vars is None: | |
57 vars = {} | |
58 if shared: | |
59 parent = vars | |
60 else: | |
61 parent = dict(globals or (), **vars) | |
62 if locals: | |
63 # if the parent is shared a copy should be created because | |
64 # we don't want to modify the dict passed | |
65 if shared: | |
66 parent = dict(parent) | |
67 for key, value in iteritems(locals): | |
68 if key[:2] == 'l_' and value is not missing: | |
69 parent[key[2:]] = value | |
70 return Context(environment, parent, template_name, blocks) | |
71 | |
72 | |
73 class TemplateReference(object): | |
74 """The `self` in templates.""" | |
75 | |
76 def __init__(self, context): | |
77 self.__context = context | |
78 | |
79 def __getitem__(self, name): | |
80 blocks = self.__context.blocks[name] | |
81 return BlockReference(name, self.__context, blocks, 0) | |
82 | |
83 def __repr__(self): | |
84 return '<%s %r>' % ( | |
85 self.__class__.__name__, | |
86 self.__context.name | |
87 ) | |
88 | |
89 | |
90 class Context(object): | |
91 """The template context holds the variables of a template. It stores the | |
92 values passed to the template and also the names the template exports. | |
93 Creating instances is neither supported nor useful as it's created | |
94 automatically at various stages of the template evaluation and should not | |
95 be created by hand. | |
96 | |
97 The context is immutable. Modifications on :attr:`parent` **must not** | |
98 happen and modifications on :attr:`vars` are allowed from generated | |
99 template code only. Template filters and global functions marked as | |
100 :func:`contextfunction`\s get the active context passed as first argument | |
101 and are allowed to access the context read-only. | |
102 | |
103 The template context supports read only dict operations (`get`, | |
104 `keys`, `values`, `items`, `iterkeys`, `itervalues`, `iteritems`, | |
105 `__getitem__`, `__contains__`). Additionally there is a :meth:`resolve` | |
106 method that doesn't fail with a `KeyError` but returns an | |
107 :class:`Undefined` object for missing variables. | |
108 """ | |
109 __slots__ = ('parent', 'vars', 'environment', 'eval_ctx', 'exported_vars', | |
110 'name', 'blocks', '__weakref__') | |
111 | |
112 def __init__(self, environment, parent, name, blocks): | |
113 self.parent = parent | |
114 self.vars = {} | |
115 self.environment = environment | |
116 self.eval_ctx = EvalContext(self.environment, name) | |
117 self.exported_vars = set() | |
118 self.name = name | |
119 | |
120 # create the initial mapping of blocks. Whenever template inheritance | |
121 # takes place the runtime will update this mapping with the new blocks | |
122 # from the template. | |
123 self.blocks = dict((k, [v]) for k, v in iteritems(blocks)) | |
124 | |
125 def super(self, name, current): | |
126 """Render a parent block.""" | |
127 try: | |
128 blocks = self.blocks[name] | |
129 index = blocks.index(current) + 1 | |
130 blocks[index] | |
131 except LookupError: | |
132 return self.environment.undefined('there is no parent block ' | |
133 'called %r.' % name, | |
134 name='super') | |
135 return BlockReference(name, self, blocks, index) | |
136 | |
137 def get(self, key, default=None): | |
138 """Returns an item from the template context, if it doesn't exist | |
139 `default` is returned. | |
140 """ | |
141 try: | |
142 return self[key] | |
143 except KeyError: | |
144 return default | |
145 | |
146 def resolve(self, key): | |
147 """Looks up a variable like `__getitem__` or `get` but returns an | |
148 :class:`Undefined` object with the name of the name looked up. | |
149 """ | |
150 if key in self.vars: | |
151 return self.vars[key] | |
152 if key in self.parent: | |
153 return self.parent[key] | |
154 return self.environment.undefined(name=key) | |
155 | |
156 def get_exported(self): | |
157 """Get a new dict with the exported variables.""" | |
158 return dict((k, self.vars[k]) for k in self.exported_vars) | |
159 | |
160 def get_all(self): | |
161 """Return a copy of the complete context as dict including the | |
162 exported variables. | |
163 """ | |
164 return dict(self.parent, **self.vars) | |
165 | |
166 @internalcode | |
167 def call(__self, __obj, *args, **kwargs): | |
168 """Call the callable with the arguments and keyword arguments | |
169 provided but inject the active context or environment as first | |
170 argument if the callable is a :func:`contextfunction` or | |
171 :func:`environmentfunction`. | |
172 """ | |
173 if __debug__: | |
174 __traceback_hide__ = True | |
175 | |
176 # Allow callable classes to take a context | |
177 fn = __obj.__call__ | |
178 for fn_type in ('contextfunction', | |
179 'evalcontextfunction', | |
180 'environmentfunction'): | |
181 if hasattr(fn, fn_type): | |
182 __obj = fn | |
183 break | |
184 | |
185 if isinstance(__obj, _context_function_types): | |
186 if getattr(__obj, 'contextfunction', 0): | |
187 args = (__self,) + args | |
188 elif getattr(__obj, 'evalcontextfunction', 0): | |
189 args = (__self.eval_ctx,) + args | |
190 elif getattr(__obj, 'environmentfunction', 0): | |
191 args = (__self.environment,) + args | |
192 try: | |
193 return __obj(*args, **kwargs) | |
194 except StopIteration: | |
195 return __self.environment.undefined('value was undefined because ' | |
196 'a callable raised a ' | |
197 'StopIteration exception') | |
198 | |
199 def derived(self, locals=None): | |
200 """Internal helper function to create a derived context.""" | |
201 context = new_context(self.environment, self.name, {}, | |
202 self.parent, True, None, locals) | |
203 context.vars.update(self.vars) | |
204 context.eval_ctx = self.eval_ctx | |
205 context.blocks.update((k, list(v)) for k, v in iteritems(self.blocks)) | |
206 return context | |
207 | |
208 def _all(meth): | |
209 proxy = lambda self: getattr(self.get_all(), meth)() | |
210 proxy.__doc__ = getattr(dict, meth).__doc__ | |
211 proxy.__name__ = meth | |
212 return proxy | |
213 | |
214 keys = _all('keys') | |
215 values = _all('values') | |
216 items = _all('items') | |
217 | |
218 # not available on python 3 | |
219 if PY2: | |
220 iterkeys = _all('iterkeys') | |
221 itervalues = _all('itervalues') | |
222 iteritems = _all('iteritems') | |
223 del _all | |
224 | |
225 def __contains__(self, name): | |
226 return name in self.vars or name in self.parent | |
227 | |
228 def __getitem__(self, key): | |
229 """Lookup a variable or raise `KeyError` if the variable is | |
230 undefined. | |
231 """ | |
232 item = self.resolve(key) | |
233 if isinstance(item, Undefined): | |
234 raise KeyError(key) | |
235 return item | |
236 | |
237 def __repr__(self): | |
238 return '<%s %s of %r>' % ( | |
239 self.__class__.__name__, | |
240 repr(self.get_all()), | |
241 self.name | |
242 ) | |
243 | |
244 | |
245 # register the context as mapping if possible | |
246 try: | |
247 from collections import Mapping | |
248 Mapping.register(Context) | |
249 except ImportError: | |
250 pass | |
251 | |
252 | |
253 class BlockReference(object): | |
254 """One block on a template reference.""" | |
255 | |
256 def __init__(self, name, context, stack, depth): | |
257 self.name = name | |
258 self._context = context | |
259 self._stack = stack | |
260 self._depth = depth | |
261 | |
262 @property | |
263 def super(self): | |
264 """Super the block.""" | |
265 if self._depth + 1 >= len(self._stack): | |
266 return self._context.environment. \ | |
267 undefined('there is no parent block called %r.' % | |
268 self.name, name='super') | |
269 return BlockReference(self.name, self._context, self._stack, | |
270 self._depth + 1) | |
271 | |
272 @internalcode | |
273 def __call__(self): | |
274 rv = concat(self._stack[self._depth](self._context)) | |
275 if self._context.eval_ctx.autoescape: | |
276 rv = Markup(rv) | |
277 return rv | |
278 | |
279 | |
280 class LoopContext(object): | |
281 """A loop context for dynamic iteration.""" | |
282 | |
283 def __init__(self, iterable, recurse=None, depth0=0): | |
284 self._iterator = iter(iterable) | |
285 self._recurse = recurse | |
286 self._after = self._safe_next() | |
287 self.index0 = -1 | |
288 self.depth0 = depth0 | |
289 | |
290 # try to get the length of the iterable early. This must be done | |
291 # here because there are some broken iterators around where there | |
292 # __len__ is the number of iterations left (i'm looking at your | |
293 # listreverseiterator!). | |
294 try: | |
295 self._length = len(iterable) | |
296 except (TypeError, AttributeError): | |
297 self._length = None | |
298 | |
299 def cycle(self, *args): | |
300 """Cycles among the arguments with the current loop index.""" | |
301 if not args: | |
302 raise TypeError('no items for cycling given') | |
303 return args[self.index0 % len(args)] | |
304 | |
305 first = property(lambda x: x.index0 == 0) | |
306 last = property(lambda x: x._after is _last_iteration) | |
307 index = property(lambda x: x.index0 + 1) | |
308 revindex = property(lambda x: x.length - x.index0) | |
309 revindex0 = property(lambda x: x.length - x.index) | |
310 depth = property(lambda x: x.depth0 + 1) | |
311 | |
312 def __len__(self): | |
313 return self.length | |
314 | |
315 def __iter__(self): | |
316 return LoopContextIterator(self) | |
317 | |
318 def _safe_next(self): | |
319 try: | |
320 return next(self._iterator) | |
321 except StopIteration: | |
322 return _last_iteration | |
323 | |
324 @internalcode | |
325 def loop(self, iterable): | |
326 if self._recurse is None: | |
327 raise TypeError('Tried to call non recursive loop. Maybe you ' | |
328 "forgot the 'recursive' modifier.") | |
329 return self._recurse(iterable, self._recurse, self.depth0 + 1) | |
330 | |
331 # a nifty trick to enhance the error message if someone tried to call | |
332 # the the loop without or with too many arguments. | |
333 __call__ = loop | |
334 del loop | |
335 | |
336 @property | |
337 def length(self): | |
338 if self._length is None: | |
339 # if was not possible to get the length of the iterator when | |
340 # the loop context was created (ie: iterating over a generator) | |
341 # we have to convert the iterable into a sequence and use the | |
342 # length of that. | |
343 iterable = tuple(self._iterator) | |
344 self._iterator = iter(iterable) | |
345 self._length = len(iterable) + self.index0 + 1 | |
346 return self._length | |
347 | |
348 def __repr__(self): | |
349 return '<%s %r/%r>' % ( | |
350 self.__class__.__name__, | |
351 self.index, | |
352 self.length | |
353 ) | |
354 | |
355 | |
356 @implements_iterator | |
357 class LoopContextIterator(object): | |
358 """The iterator for a loop context.""" | |
359 __slots__ = ('context',) | |
360 | |
361 def __init__(self, context): | |
362 self.context = context | |
363 | |
364 def __iter__(self): | |
365 return self | |
366 | |
367 def __next__(self): | |
368 ctx = self.context | |
369 ctx.index0 += 1 | |
370 if ctx._after is _last_iteration: | |
371 raise StopIteration() | |
372 next_elem = ctx._after | |
373 ctx._after = ctx._safe_next() | |
374 return next_elem, ctx | |
375 | |
376 | |
377 class Macro(object): | |
378 """Wraps a macro function.""" | |
379 | |
380 def __init__(self, environment, func, name, arguments, defaults, | |
381 catch_kwargs, catch_varargs, caller): | |
382 self._environment = environment | |
383 self._func = func | |
384 self._argument_count = len(arguments) | |
385 self.name = name | |
386 self.arguments = arguments | |
387 self.defaults = defaults | |
388 self.catch_kwargs = catch_kwargs | |
389 self.catch_varargs = catch_varargs | |
390 self.caller = caller | |
391 | |
392 @internalcode | |
393 def __call__(self, *args, **kwargs): | |
394 # try to consume the positional arguments | |
395 arguments = list(args[:self._argument_count]) | |
396 off = len(arguments) | |
397 | |
398 # if the number of arguments consumed is not the number of | |
399 # arguments expected we start filling in keyword arguments | |
400 # and defaults. | |
401 if off != self._argument_count: | |
402 for idx, name in enumerate(self.arguments[len(arguments):]): | |
403 try: | |
404 value = kwargs.pop(name) | |
405 except KeyError: | |
406 try: | |
407 value = self.defaults[idx - self._argument_count + off] | |
408 except IndexError: | |
409 value = self._environment.undefined( | |
410 'parameter %r was not provided' % name, name=name) | |
411 arguments.append(value) | |
412 | |
413 # it's important that the order of these arguments does not change | |
414 # if not also changed in the compiler's `function_scoping` method. | |
415 # the order is caller, keyword arguments, positional arguments! | |
416 if self.caller: | |
417 caller = kwargs.pop('caller', None) | |
418 if caller is None: | |
419 caller = self._environment.undefined('No caller defined', | |
420 name='caller') | |
421 arguments.append(caller) | |
422 if self.catch_kwargs: | |
423 arguments.append(kwargs) | |
424 elif kwargs: | |
425 raise TypeError('macro %r takes no keyword argument %r' % | |
426 (self.name, next(iter(kwargs)))) | |
427 if self.catch_varargs: | |
428 arguments.append(args[self._argument_count:]) | |
429 elif len(args) > self._argument_count: | |
430 raise TypeError('macro %r takes not more than %d argument(s)' % | |
431 (self.name, len(self.arguments))) | |
432 return self._func(*arguments) | |
433 | |
434 def __repr__(self): | |
435 return '<%s %s>' % ( | |
436 self.__class__.__name__, | |
437 self.name is None and 'anonymous' or repr(self.name) | |
438 ) | |
439 | |
440 | |
441 @implements_to_string | |
442 class Undefined(object): | |
443 """The default undefined type. This undefined type can be printed and | |
444 iterated over, but every other access will raise an :exc:`UndefinedError`: | |
445 | |
446 >>> foo = Undefined(name='foo') | |
447 >>> str(foo) | |
448 '' | |
449 >>> not foo | |
450 True | |
451 >>> foo + 42 | |
452 Traceback (most recent call last): | |
453 ... | |
454 UndefinedError: 'foo' is undefined | |
455 """ | |
456 __slots__ = ('_undefined_hint', '_undefined_obj', '_undefined_name', | |
457 '_undefined_exception') | |
458 | |
459 def __init__(self, hint=None, obj=missing, name=None, exc=UndefinedError): | |
460 self._undefined_hint = hint | |
461 self._undefined_obj = obj | |
462 self._undefined_name = name | |
463 self._undefined_exception = exc | |
464 | |
465 @internalcode | |
466 def _fail_with_undefined_error(self, *args, **kwargs): | |
467 """Regular callback function for undefined objects that raises an | |
468 `UndefinedError` on call. | |
469 """ | |
470 if self._undefined_hint is None: | |
471 if self._undefined_obj is missing: | |
472 hint = '%r is undefined' % self._undefined_name | |
473 elif not isinstance(self._undefined_name, string_types): | |
474 hint = '%s has no element %r' % ( | |
475 object_type_repr(self._undefined_obj), | |
476 self._undefined_name | |
477 ) | |
478 else: | |
479 hint = '%r has no attribute %r' % ( | |
480 object_type_repr(self._undefined_obj), | |
481 self._undefined_name | |
482 ) | |
483 else: | |
484 hint = self._undefined_hint | |
485 raise self._undefined_exception(hint) | |
486 | |
487 @internalcode | |
488 def __getattr__(self, name): | |
489 if name[:2] == '__': | |
490 raise AttributeError(name) | |
491 return self._fail_with_undefined_error() | |
492 | |
493 __add__ = __radd__ = __mul__ = __rmul__ = __div__ = __rdiv__ = \ | |
494 __truediv__ = __rtruediv__ = __floordiv__ = __rfloordiv__ = \ | |
495 __mod__ = __rmod__ = __pos__ = __neg__ = __call__ = \ | |
496 __getitem__ = __lt__ = __le__ = __gt__ = __ge__ = __int__ = \ | |
497 __float__ = __complex__ = __pow__ = __rpow__ = \ | |
498 _fail_with_undefined_error | |
499 | |
500 def __eq__(self, other): | |
501 return type(self) is type(other) | |
502 | |
503 def __ne__(self, other): | |
504 return not self.__eq__(other) | |
505 | |
506 def __hash__(self): | |
507 return id(type(self)) | |
508 | |
509 def __str__(self): | |
510 return u'' | |
511 | |
512 def __len__(self): | |
513 return 0 | |
514 | |
515 def __iter__(self): | |
516 if 0: | |
517 yield None | |
518 | |
519 def __nonzero__(self): | |
520 return False | |
521 | |
522 def __repr__(self): | |
523 return 'Undefined' | |
524 | |
525 | |
526 @implements_to_string | |
527 class DebugUndefined(Undefined): | |
528 """An undefined that returns the debug info when printed. | |
529 | |
530 >>> foo = DebugUndefined(name='foo') | |
531 >>> str(foo) | |
532 '{{ foo }}' | |
533 >>> not foo | |
534 True | |
535 >>> foo + 42 | |
536 Traceback (most recent call last): | |
537 ... | |
538 UndefinedError: 'foo' is undefined | |
539 """ | |
540 __slots__ = () | |
541 | |
542 def __str__(self): | |
543 if self._undefined_hint is None: | |
544 if self._undefined_obj is missing: | |
545 return u'{{ %s }}' % self._undefined_name | |
546 return '{{ no such element: %s[%r] }}' % ( | |
547 object_type_repr(self._undefined_obj), | |
548 self._undefined_name | |
549 ) | |
550 return u'{{ undefined value printed: %s }}' % self._undefined_hint | |
551 | |
552 | |
553 @implements_to_string | |
554 class StrictUndefined(Undefined): | |
555 """An undefined that barks on print and iteration as well as boolean | |
556 tests and all kinds of comparisons. In other words: you can do nothing | |
557 with it except checking if it's defined using the `defined` test. | |
558 | |
559 >>> foo = StrictUndefined(name='foo') | |
560 >>> str(foo) | |
561 Traceback (most recent call last): | |
562 ... | |
563 UndefinedError: 'foo' is undefined | |
564 >>> not foo | |
565 Traceback (most recent call last): | |
566 ... | |
567 UndefinedError: 'foo' is undefined | |
568 >>> foo + 42 | |
569 Traceback (most recent call last): | |
570 ... | |
571 UndefinedError: 'foo' is undefined | |
572 """ | |
573 __slots__ = () | |
574 __iter__ = __str__ = __len__ = __nonzero__ = __eq__ = \ | |
575 __ne__ = __bool__ = __hash__ = \ | |
576 Undefined._fail_with_undefined_error | |
577 | |
578 | |
579 # remove remaining slots attributes, after the metaclass did the magic they | |
580 # are unneeded and irritating as they contain wrong data for the subclasses. | |
581 del Undefined.__slots__, DebugUndefined.__slots__, StrictUndefined.__slots__ | |
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