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: Copyright 2008 by Armin Ronacher.
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
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 def __init__(self, environment):
61 self.environment = environment
63 def bind(self, environment):
64 """Create a copy of this extension bound to another environment."""
65 rv = object.__new__(self.__class__)
66 rv.__dict__.update(self.__dict__)
67 rv.environment = environment
70 def preprocess(self, source, name, filename=None):
71 """This method is called before the actual lexing and can be used to
72 preprocess the source. The `filename` is optional. The return value
73 must be the preprocessed source.
77 def filter_stream(self, stream):
78 """It's passed a :class:`~jinja2.lexer.TokenStream` that can be used
79 to filter tokens returned. This method has to return an iterable of
80 :class:`~jinja2.lexer.Token`\s, but it doesn't have to return a
81 :class:`~jinja2.lexer.TokenStream`.
83 In the `ext` folder of the Jinja2 source distribution there is a file
84 called `inlinegettext.py` which implements a filter that utilizes this
89 def parse(self, parser):
90 """If any of the :attr:`tags` matched this method is called with the
91 parser as first argument. The token the parser stream is pointing at
92 is the name token that matched. This method has to return one or a
93 list of multiple nodes.
95 raise NotImplementedError()
97 def attr(self, name, lineno=None):
98 """Return an attribute node for the current extension. This is useful
99 to pass constants on extensions to generated template code::
101 self.attr('_my_attribute', lineno=lineno)
103 return nodes.ExtensionAttribute(self.identifier, name, lineno=lineno)
105 def call_method(self, name, args=None, kwargs=None, dyn_args=None,
106 dyn_kwargs=None, lineno=None):
107 """Call a method of the extension. This is a shortcut for
108 :meth:`attr` + :class:`jinja2.nodes.Call`.
114 return nodes.Call(self.attr(name, lineno=lineno), args, kwargs,
115 dyn_args, dyn_kwargs, lineno=lineno)
119 def _gettext_alias(context, string):
120 return context.resolve('gettext')(string)
123 class InternationalizationExtension(Extension):
124 """This extension adds gettext support to Jinja2."""
125 tags = set(['trans'])
127 def __init__(self, environment):
128 Extension.__init__(self, environment)
129 environment.globals['_'] = _gettext_alias
131 install_gettext_translations=self._install,
132 install_null_translations=self._install_null,
133 uninstall_gettext_translations=self._uninstall,
134 extract_translations=self._extract
137 def _install(self, translations):
138 self.environment.globals.update(
139 gettext=translations.ugettext,
140 ngettext=translations.ungettext
143 def _install_null(self):
144 self.environment.globals.update(
146 ngettext=lambda s, p, n: (n != 1 and (p,) or (s,))[0]
149 def _uninstall(self, translations):
150 for key in 'gettext', 'ngettext':
151 self.environment.globals.pop(key, None)
153 def _extract(self, source, gettext_functions=GETTEXT_FUNCTIONS):
154 if isinstance(source, basestring):
155 source = self.environment.parse(source)
156 return extract_from_ast(source, gettext_functions)
158 def parse(self, parser):
159 """Parse a translatable tag."""
160 lineno = parser.stream.next().lineno
162 # find all the variables referenced. Additionally a variable can be
163 # defined in the body of the trans block too, but this is checked at
167 while parser.stream.current.type is not 'block_end':
169 parser.stream.expect('comma')
171 # skip colon for python compatibility
172 if parser.stream.skip_if('colon'):
175 name = parser.stream.expect('name')
176 if name.value in variables:
177 parser.fail('translatable variable %r defined twice.' %
178 name.value, name.lineno,
179 exc=TemplateAssertionError)
182 if parser.stream.current.type is 'assign':
184 variables[name.value] = var = parser.parse_expression()
186 variables[name.value] = var = nodes.Name(name.value, 'load')
187 if plural_expr is None:
190 parser.stream.expect('block_end')
192 plural = plural_names = None
196 # now parse until endtrans or pluralize
197 singular_names, singular = self._parse_block(parser, True)
199 referenced.update(singular_names)
200 if plural_expr is None:
201 plural_expr = nodes.Name(singular_names[0], 'load')
203 # if we have a pluralize block, we parse that too
204 if parser.stream.current.test('name:pluralize'):
207 if parser.stream.current.type is not 'block_end':
208 plural_expr = parser.parse_expression()
209 parser.stream.expect('block_end')
210 plural_names, plural = self._parse_block(parser, False)
212 referenced.update(plural_names)
216 # register free names as simple name expressions
217 for var in referenced:
218 if var not in variables:
219 variables[var] = nodes.Name(var, 'load')
221 # no variables referenced? no need to escape
223 singular = singular.replace('%%', '%')
225 plural = plural.replace('%%', '%')
229 elif plural_expr is None:
230 parser.fail('pluralize without variables', lineno)
233 variables = nodes.Dict([nodes.Pair(nodes.Const(x, lineno=lineno), y)
234 for x, y in variables.items()])
238 node = self._make_node(singular, plural, variables, plural_expr)
239 node.set_lineno(lineno)
242 def _parse_block(self, parser, allow_pluralize):
243 """Parse until the next block tag with a given name."""
247 if parser.stream.current.type is 'data':
248 buf.append(parser.stream.current.value.replace('%', '%%'))
250 elif parser.stream.current.type is 'variable_begin':
252 name = parser.stream.expect('name').value
253 referenced.append(name)
254 buf.append('%%(%s)s' % name)
255 parser.stream.expect('variable_end')
256 elif parser.stream.current.type is 'block_begin':
258 if parser.stream.current.test('name:endtrans'):
260 elif parser.stream.current.test('name:pluralize'):
263 parser.fail('a translatable section can have only one '
265 parser.fail('control structures in translatable sections are '
267 elif parser.stream.eos:
268 parser.fail('unclosed translation block')
270 assert False, 'internal parser error'
272 return referenced, concat(buf)
274 def _make_node(self, singular, plural, variables, plural_expr):
275 """Generates a useful node from the data provided."""
277 if plural_expr is None:
278 gettext = nodes.Name('gettext', 'load')
279 node = nodes.Call(gettext, [nodes.Const(singular)],
282 # singular and plural
284 ngettext = nodes.Name('ngettext', 'load')
285 node = nodes.Call(ngettext, [
286 nodes.Const(singular),
291 # mark the return value as safe if we are in an
292 # environment with autoescaping turned on
293 if self.environment.autoescape:
294 node = nodes.MarkSafe(node)
297 node = nodes.Mod(node, variables)
298 return nodes.Output([node])
301 class ExprStmtExtension(Extension):
302 """Adds a `do` tag to Jinja2 that works like the print statement just
303 that it doesn't print the return value.
307 def parse(self, parser):
308 node = nodes.ExprStmt(lineno=parser.stream.next().lineno)
309 node.node = parser.parse_tuple()
313 class LoopControlExtension(Extension):
314 """Adds break and continue to the template engine."""
315 tags = set(['break', 'continue'])
317 def parse(self, parser):
318 token = parser.stream.next()
319 if token.value == 'break':
320 return nodes.Break(lineno=token.lineno)
321 return nodes.Continue(lineno=token.lineno)
324 def extract_from_ast(node, gettext_functions=GETTEXT_FUNCTIONS,
326 """Extract localizable strings from the given template node. Per
327 default this function returns matches in babel style that means non string
328 parameters as well as keyword arguments are returned as `None`. This
329 allows Babel to figure out what you really meant if you are using
330 gettext functions that allow keyword arguments for placeholder expansion.
331 If you don't want that behavior set the `babel_style` parameter to `False`
332 which causes only strings to be returned and parameters are always stored
333 in tuples. As a consequence invalid gettext calls (calls without a single
334 string parameter or string parameters after non-string parameters) are
337 This example explains the behavior:
339 >>> from jinja2 import Environment
340 >>> env = Environment()
341 >>> node = env.parse('{{ (_("foo"), _(), ngettext("foo", "bar", 42)) }}')
342 >>> list(extract_from_ast(node))
343 [(1, '_', 'foo'), (1, '_', ()), (1, 'ngettext', ('foo', 'bar', None))]
344 >>> list(extract_from_ast(node, babel_style=False))
345 [(1, '_', ('foo',)), (1, 'ngettext', ('foo', 'bar'))]
347 For every string found this function yields a ``(lineno, function,
348 message)`` tuple, where:
350 * ``lineno`` is the number of the line on which the string was found,
351 * ``function`` is the name of the ``gettext`` function used (if the
352 string was extracted from embedded Python code), and
353 * ``message`` is the string itself (a ``unicode`` object, or a tuple
354 of ``unicode`` objects for functions with multiple string arguments).
356 for node in node.find_all(nodes.Call):
357 if not isinstance(node.node, nodes.Name) or \
358 node.node.name not in gettext_functions:
362 for arg in node.args:
363 if isinstance(arg, nodes.Const) and \
364 isinstance(arg.value, basestring):
365 strings.append(arg.value)
369 for arg in node.kwargs:
371 if node.dyn_args is not None:
373 if node.dyn_kwargs is not None:
377 strings = tuple(x for x in strings if x is not None)
381 if len(strings) == 1:
384 strings = tuple(strings)
385 yield node.lineno, node.node.name, strings
388 def babel_extract(fileobj, keywords, comment_tags, options):
389 """Babel extraction method for Jinja templates.
391 :param fileobj: the file-like object the messages should be extracted from
392 :param keywords: a list of keywords (i.e. function names) that should be
393 recognized as translation functions
394 :param comment_tags: a list of translator tags to search for and include
395 in the results. (Unused)
396 :param options: a dictionary of additional options (optional)
397 :return: an iterator over ``(lineno, funcname, message, comments)`` tuples.
398 (comments will be empty currently)
401 for extension in options.get('extensions', '').split(','):
402 extension = extension.strip()
405 extensions.add(import_string(extension))
406 if InternationalizationExtension not in extensions:
407 extensions.add(InternationalizationExtension)
409 environment = get_spontaneous_environment(
410 options.get('block_start_string', BLOCK_START_STRING),
411 options.get('block_end_string', BLOCK_END_STRING),
412 options.get('variable_start_string', VARIABLE_START_STRING),
413 options.get('variable_end_string', VARIABLE_END_STRING),
414 options.get('comment_start_string', COMMENT_START_STRING),
415 options.get('comment_end_string', COMMENT_END_STRING),
416 options.get('line_statement_prefix') or LINE_STATEMENT_PREFIX,
417 str(options.get('trim_blocks', TRIM_BLOCKS)).lower() in \
418 ('1', 'on', 'yes', 'true'),
419 NEWLINE_SEQUENCE, frozenset(extensions),
420 # fill with defaults so that environments are shared
421 # with other spontaneus environments. The rest of the
422 # arguments are optimizer, undefined, finalize, autoescape,
423 # loader, cache size and auto reloading setting
424 True, Undefined, None, False, None, 0, False
427 source = fileobj.read().decode(options.get('encoding', 'utf-8'))
429 node = environment.parse(source)
430 except TemplateSyntaxError, e:
431 # skip templates with syntax errors
433 for lineno, func, message in extract_from_ast(node, keywords):
434 yield lineno, func, message, []
437 #: nicer import names
438 i18n = InternationalizationExtension
439 do = ExprStmtExtension
440 loopcontrols = LoopControlExtension