1 # -*- coding: utf-8 -*-
6 Jinja extensions allow to add custom tags similar to the way django custom
7 tags work. By default two example extensions exist: an i18n and a cache
10 :copyright: (c) 2010 by the Jinja Team.
13 from collections import deque
14 from jinja2 import nodes
15 from jinja2.defaults import *
16 from jinja2.environment import get_spontaneous_environment
17 from jinja2.runtime import Undefined, concat
18 from jinja2.exceptions import TemplateAssertionError, TemplateSyntaxError
19 from jinja2.utils import contextfunction, import_string, Markup, next
22 # the only real useful gettext functions for a Jinja template. Note
23 # that ugettext must be assigned to gettext as Jinja doesn't support
24 # non unicode strings.
25 GETTEXT_FUNCTIONS = ('_', 'gettext', 'ngettext')
28 class ExtensionRegistry(type):
29 """Gives the extension an unique identifier."""
31 def __new__(cls, name, bases, d):
32 rv = type.__new__(cls, name, bases, d)
33 rv.identifier = rv.__module__ + '.' + rv.__name__
37 class Extension(object):
38 """Extensions can be used to add extra functionality to the Jinja template
39 system at the parser level. Custom extensions are bound to an environment
40 but may not store environment specific data on `self`. The reason for
41 this is that an extension can be bound to another environment (for
42 overlays) by creating a copy and reassigning the `environment` attribute.
44 As extensions are created by the environment they cannot accept any
45 arguments for configuration. One may want to work around that by using
46 a factory function, but that is not possible as extensions are identified
47 by their import name. The correct way to configure the extension is
48 storing the configuration values on the environment. Because this way the
49 environment ends up acting as central configuration storage the
50 attributes may clash which is why extensions have to ensure that the names
51 they choose for configuration are not too generic. ``prefix`` for example
52 is a terrible name, ``fragment_cache_prefix`` on the other hand is a good
53 name as includes the name of the extension (fragment cache).
55 __metaclass__ = ExtensionRegistry
57 #: if this extension parses this is the list of tags it's listening to.
60 #: the priority of that extension. This is especially useful for
61 #: extensions that preprocess values. A lower value means higher
64 #: .. versionadded:: 2.4
67 def __init__(self, environment):
68 self.environment = environment
70 def bind(self, environment):
71 """Create a copy of this extension bound to another environment."""
72 rv = object.__new__(self.__class__)
73 rv.__dict__.update(self.__dict__)
74 rv.environment = environment
77 def preprocess(self, source, name, filename=None):
78 """This method is called before the actual lexing and can be used to
79 preprocess the source. The `filename` is optional. The return value
80 must be the preprocessed source.
84 def filter_stream(self, stream):
85 """It's passed a :class:`~jinja2.lexer.TokenStream` that can be used
86 to filter tokens returned. This method has to return an iterable of
87 :class:`~jinja2.lexer.Token`\s, but it doesn't have to return a
88 :class:`~jinja2.lexer.TokenStream`.
90 In the `ext` folder of the Jinja2 source distribution there is a file
91 called `inlinegettext.py` which implements a filter that utilizes this
96 def parse(self, parser):
97 """If any of the :attr:`tags` matched this method is called with the
98 parser as first argument. The token the parser stream is pointing at
99 is the name token that matched. This method has to return one or a
100 list of multiple nodes.
102 raise NotImplementedError()
104 def attr(self, name, lineno=None):
105 """Return an attribute node for the current extension. This is useful
106 to pass constants on extensions to generated template code::
108 self.attr('_my_attribute', lineno=lineno)
110 return nodes.ExtensionAttribute(self.identifier, name, lineno=lineno)
112 def call_method(self, name, args=None, kwargs=None, dyn_args=None,
113 dyn_kwargs=None, lineno=None):
114 """Call a method of the extension. This is a shortcut for
115 :meth:`attr` + :class:`jinja2.nodes.Call`.
121 return nodes.Call(self.attr(name, lineno=lineno), args, kwargs,
122 dyn_args, dyn_kwargs, lineno=lineno)
126 def _gettext_alias(__context, *args, **kwargs):
127 return __context.call(__context.resolve('gettext'), *args, **kwargs)
130 def _make_new_gettext(func):
132 def gettext(__context, __string, **variables):
133 rv = __context.call(func, __string)
134 if __context.eval_ctx.autoescape:
136 return rv % variables
140 def _make_new_ngettext(func):
142 def ngettext(__context, __singular, __plural, num, **variables):
143 variables.setdefault('num', num)
144 rv = __context.call(func, __singular, __plural, num)
145 if __context.eval_ctx.autoescape:
147 return rv % variables
151 class InternationalizationExtension(Extension):
152 """This extension adds gettext support to Jinja2."""
153 tags = set(['trans'])
155 # TODO: the i18n extension is currently reevaluating values in a few
156 # situations. Take this example:
157 # {% trans count=something() %}{{ count }} foo{% pluralize
158 # %}{{ count }} fooss{% endtrans %}
159 # something is called twice here. One time for the gettext value and
160 # the other time for the n-parameter of the ngettext function.
162 def __init__(self, environment):
163 Extension.__init__(self, environment)
164 environment.globals['_'] = _gettext_alias
166 install_gettext_translations=self._install,
167 install_null_translations=self._install_null,
168 install_gettext_callables=self._install_callables,
169 uninstall_gettext_translations=self._uninstall,
170 extract_translations=self._extract,
171 newstyle_gettext=False
174 def _install(self, translations, newstyle=None):
175 gettext = getattr(translations, 'ugettext', None)
177 gettext = translations.gettext
178 ngettext = getattr(translations, 'ungettext', None)
180 ngettext = translations.ngettext
181 self._install_callables(gettext, ngettext, newstyle)
183 def _install_null(self, newstyle=None):
184 self._install_callables(
186 lambda s, p, n: (n != 1 and (p,) or (s,))[0],
190 def _install_callables(self, gettext, ngettext, newstyle=None):
191 if newstyle is not None:
192 self.environment.newstyle_gettext = newstyle
193 if self.environment.newstyle_gettext:
194 gettext = _make_new_gettext(gettext)
195 ngettext = _make_new_ngettext(ngettext)
196 self.environment.globals.update(
201 def _uninstall(self, translations):
202 for key in 'gettext', 'ngettext':
203 self.environment.globals.pop(key, None)
205 def _extract(self, source, gettext_functions=GETTEXT_FUNCTIONS):
206 if isinstance(source, basestring):
207 source = self.environment.parse(source)
208 return extract_from_ast(source, gettext_functions)
210 def parse(self, parser):
211 """Parse a translatable tag."""
212 lineno = next(parser.stream).lineno
214 # find all the variables referenced. Additionally a variable can be
215 # defined in the body of the trans block too, but this is checked at
219 while parser.stream.current.type != 'block_end':
221 parser.stream.expect('comma')
223 # skip colon for python compatibility
224 if parser.stream.skip_if('colon'):
227 name = parser.stream.expect('name')
228 if name.value in variables:
229 parser.fail('translatable variable %r defined twice.' %
230 name.value, name.lineno,
231 exc=TemplateAssertionError)
234 if parser.stream.current.type == 'assign':
236 variables[name.value] = var = parser.parse_expression()
238 variables[name.value] = var = nodes.Name(name.value, 'load')
239 if plural_expr is None:
242 parser.stream.expect('block_end')
244 plural = plural_names = None
248 # now parse until endtrans or pluralize
249 singular_names, singular = self._parse_block(parser, True)
251 referenced.update(singular_names)
252 if plural_expr is None:
253 plural_expr = nodes.Name(singular_names[0], 'load')
255 # if we have a pluralize block, we parse that too
256 if parser.stream.current.test('name:pluralize'):
259 if parser.stream.current.type != 'block_end':
260 name = parser.stream.expect('name')
261 if name.value not in variables:
262 parser.fail('unknown variable %r for pluralization' %
263 name.value, name.lineno,
264 exc=TemplateAssertionError)
265 plural_expr = variables[name.value]
266 parser.stream.expect('block_end')
267 plural_names, plural = self._parse_block(parser, False)
269 referenced.update(plural_names)
273 # register free names as simple name expressions
274 for var in referenced:
275 if var not in variables:
276 variables[var] = nodes.Name(var, 'load')
278 # no variables referenced? no need to escape
280 singular = singular.replace('%%', '%')
282 plural = plural.replace('%%', '%')
286 elif plural_expr is None:
287 parser.fail('pluralize without variables', lineno)
289 node = self._make_node(singular, plural, variables, plural_expr)
290 node.set_lineno(lineno)
293 def _parse_block(self, parser, allow_pluralize):
294 """Parse until the next block tag with a given name."""
298 if parser.stream.current.type == 'data':
299 buf.append(parser.stream.current.value.replace('%', '%%'))
301 elif parser.stream.current.type == 'variable_begin':
303 name = parser.stream.expect('name').value
304 referenced.append(name)
305 buf.append('%%(%s)s' % name)
306 parser.stream.expect('variable_end')
307 elif parser.stream.current.type == 'block_begin':
309 if parser.stream.current.test('name:endtrans'):
311 elif parser.stream.current.test('name:pluralize'):
314 parser.fail('a translatable section can have only one '
316 parser.fail('control structures in translatable sections are '
318 elif parser.stream.eos:
319 parser.fail('unclosed translation block')
321 assert False, 'internal parser error'
323 return referenced, concat(buf)
325 def _make_node(self, singular, plural, variables, plural_expr):
326 """Generates a useful node from the data provided."""
328 if plural_expr is None:
329 gettext = nodes.Name('gettext', 'load')
330 node = nodes.Call(gettext, [nodes.Const(singular)],
333 # singular and plural
335 ngettext = nodes.Name('ngettext', 'load')
336 node = nodes.Call(ngettext, [
337 nodes.Const(singular),
342 # in case newstyle gettext is used, the method is powerful
343 # enough to handle the variable expansion and autoescape
345 if self.environment.newstyle_gettext:
346 for key, value in variables.iteritems():
347 node.kwargs.append(nodes.Keyword(key, value))
349 # otherwise do that here
351 # mark the return value as safe if we are in an
352 # environment with autoescaping turned on
353 node = nodes.MarkSafeIfAutoescape(node)
355 node = nodes.Mod(node, nodes.Dict([
356 nodes.Pair(nodes.Const(key), value)
357 for key, value in variables.items()
359 return nodes.Output([node])
362 class ExprStmtExtension(Extension):
363 """Adds a `do` tag to Jinja2 that works like the print statement just
364 that it doesn't print the return value.
368 def parse(self, parser):
369 node = nodes.ExprStmt(lineno=next(parser.stream).lineno)
370 node.node = parser.parse_tuple()
374 class LoopControlExtension(Extension):
375 """Adds break and continue to the template engine."""
376 tags = set(['break', 'continue'])
378 def parse(self, parser):
379 token = next(parser.stream)
380 if token.value == 'break':
381 return nodes.Break(lineno=token.lineno)
382 return nodes.Continue(lineno=token.lineno)
385 class WithExtension(Extension):
386 """Adds support for a django-like with block."""
389 def parse(self, parser):
390 node = nodes.Scope(lineno=next(parser.stream).lineno)
392 while parser.stream.current.type != 'block_end':
393 lineno = parser.stream.current.lineno
395 parser.stream.expect('comma')
396 target = parser.parse_assign_target()
397 parser.stream.expect('assign')
398 expr = parser.parse_expression()
399 assignments.append(nodes.Assign(target, expr, lineno=lineno))
400 node.body = assignments + \
401 list(parser.parse_statements(('name:endwith',),
406 class AutoEscapeExtension(Extension):
407 """Changes auto escape rules for a scope."""
408 tags = set(['autoescape'])
410 def parse(self, parser):
411 node = nodes.ScopedEvalContextModifier(lineno=next(parser.stream).lineno)
413 nodes.Keyword('autoescape', parser.parse_expression())
415 node.body = parser.parse_statements(('name:endautoescape',),
417 return nodes.Scope([node])
420 def extract_from_ast(node, gettext_functions=GETTEXT_FUNCTIONS,
422 """Extract localizable strings from the given template node. Per
423 default this function returns matches in babel style that means non string
424 parameters as well as keyword arguments are returned as `None`. This
425 allows Babel to figure out what you really meant if you are using
426 gettext functions that allow keyword arguments for placeholder expansion.
427 If you don't want that behavior set the `babel_style` parameter to `False`
428 which causes only strings to be returned and parameters are always stored
429 in tuples. As a consequence invalid gettext calls (calls without a single
430 string parameter or string parameters after non-string parameters) are
433 This example explains the behavior:
435 >>> from jinja2 import Environment
436 >>> env = Environment()
437 >>> node = env.parse('{{ (_("foo"), _(), ngettext("foo", "bar", 42)) }}')
438 >>> list(extract_from_ast(node))
439 [(1, '_', 'foo'), (1, '_', ()), (1, 'ngettext', ('foo', 'bar', None))]
440 >>> list(extract_from_ast(node, babel_style=False))
441 [(1, '_', ('foo',)), (1, 'ngettext', ('foo', 'bar'))]
443 For every string found this function yields a ``(lineno, function,
444 message)`` tuple, where:
446 * ``lineno`` is the number of the line on which the string was found,
447 * ``function`` is the name of the ``gettext`` function used (if the
448 string was extracted from embedded Python code), and
449 * ``message`` is the string itself (a ``unicode`` object, or a tuple
450 of ``unicode`` objects for functions with multiple string arguments).
452 This extraction function operates on the AST and is because of that unable
453 to extract any comments. For comment support you have to use the babel
454 extraction interface or extract comments yourself.
456 for node in node.find_all(nodes.Call):
457 if not isinstance(node.node, nodes.Name) or \
458 node.node.name not in gettext_functions:
462 for arg in node.args:
463 if isinstance(arg, nodes.Const) and \
464 isinstance(arg.value, basestring):
465 strings.append(arg.value)
469 for arg in node.kwargs:
471 if node.dyn_args is not None:
473 if node.dyn_kwargs is not None:
477 strings = tuple(x for x in strings if x is not None)
481 if len(strings) == 1:
484 strings = tuple(strings)
485 yield node.lineno, node.node.name, strings
488 class _CommentFinder(object):
489 """Helper class to find comments in a token stream. Can only
490 find comments for gettext calls forwards. Once the comment
491 from line 4 is found, a comment for line 1 will not return a
495 def __init__(self, tokens, comment_tags):
497 self.comment_tags = comment_tags
501 def find_backwards(self, offset):
503 for _, token_type, token_value in \
504 reversed(self.tokens[self.offset:offset]):
505 if token_type in ('comment', 'linecomment'):
507 prefix, comment = token_value.split(None, 1)
510 if prefix in self.comment_tags:
511 return [comment.rstrip()]
516 def find_comments(self, lineno):
517 if not self.comment_tags or self.last_lineno > lineno:
519 for idx, (token_lineno, _, _) in enumerate(self.tokens[self.offset:]):
520 if token_lineno > lineno:
521 return self.find_backwards(self.offset + idx)
522 return self.find_backwards(len(self.tokens))
525 def babel_extract(fileobj, keywords, comment_tags, options):
526 """Babel extraction method for Jinja templates.
528 .. versionchanged:: 2.3
529 Basic support for translation comments was added. If `comment_tags`
530 is now set to a list of keywords for extraction, the extractor will
531 try to find the best preceeding comment that begins with one of the
532 keywords. For best results, make sure to not have more than one
533 gettext call in one line of code and the matching comment in the
534 same line or the line before.
536 :param fileobj: the file-like object the messages should be extracted from
537 :param keywords: a list of keywords (i.e. function names) that should be
538 recognized as translation functions
539 :param comment_tags: a list of translator tags to search for and include
541 :param options: a dictionary of additional options (optional)
542 :return: an iterator over ``(lineno, funcname, message, comments)`` tuples.
543 (comments will be empty currently)
546 for extension in options.get('extensions', '').split(','):
547 extension = extension.strip()
550 extensions.add(import_string(extension))
551 if InternationalizationExtension not in extensions:
552 extensions.add(InternationalizationExtension)
554 environment = get_spontaneous_environment(
555 options.get('block_start_string', BLOCK_START_STRING),
556 options.get('block_end_string', BLOCK_END_STRING),
557 options.get('variable_start_string', VARIABLE_START_STRING),
558 options.get('variable_end_string', VARIABLE_END_STRING),
559 options.get('comment_start_string', COMMENT_START_STRING),
560 options.get('comment_end_string', COMMENT_END_STRING),
561 options.get('line_statement_prefix') or LINE_STATEMENT_PREFIX,
562 options.get('line_comment_prefix') or LINE_COMMENT_PREFIX,
563 str(options.get('trim_blocks', TRIM_BLOCKS)).lower() in \
564 ('1', 'on', 'yes', 'true'),
565 NEWLINE_SEQUENCE, frozenset(extensions),
566 # fill with defaults so that environments are shared
567 # with other spontaneus environments. The rest of the
568 # arguments are optimizer, undefined, finalize, autoescape,
569 # loader, cache size, auto reloading setting and the
571 True, Undefined, None, False, None, 0, False, None
574 source = fileobj.read().decode(options.get('encoding', 'utf-8'))
576 node = environment.parse(source)
577 tokens = list(environment.lex(environment.preprocess(source)))
578 except TemplateSyntaxError, e:
579 # skip templates with syntax errors
582 finder = _CommentFinder(tokens, comment_tags)
583 for lineno, func, message in extract_from_ast(node, keywords):
584 yield lineno, func, message, finder.find_comments(lineno)
587 #: nicer import names
588 i18n = InternationalizationExtension
589 do = ExprStmtExtension
590 loopcontrols = LoopControlExtension
591 with_ = WithExtension
592 autoescape = AutoEscapeExtension