1 # -*- coding: utf-8 -*-
6 Provides a class that holds runtime and parsing time options.
8 :copyright: (c) 2010 by the Jinja Team.
9 :license: BSD, see LICENSE for more details.
12 from jinja2 import nodes
13 from jinja2.defaults import *
14 from jinja2.lexer import get_lexer, TokenStream
15 from jinja2.parser import Parser
16 from jinja2.optimizer import optimize
17 from jinja2.compiler import generate
18 from jinja2.runtime import Undefined, new_context
19 from jinja2.exceptions import TemplateSyntaxError, TemplateNotFound, \
21 from jinja2.utils import import_string, LRUCache, Markup, missing, \
22 concat, consume, internalcode, _encode_filename
25 # for direct template usage we have up to ten living environments
26 _spontaneous_environments = LRUCache(10)
28 # the function to create jinja traceback objects. This is dynamically
29 # imported on the first exception in the exception handler.
30 _make_traceback = None
33 def get_spontaneous_environment(*args):
34 """Return a new spontaneous environment. A spontaneous environment is an
35 unnamed and unaccessible (in theory) environment that is used for
36 templates generated from a string and not from the file system.
39 env = _spontaneous_environments.get(args)
41 return Environment(*args)
44 _spontaneous_environments[args] = env = Environment(*args)
49 def create_cache(size):
50 """Return the cache class for the given size."""
58 def copy_cache(cache):
59 """Create an empty copy of the given cache."""
62 elif type(cache) is dict:
64 return LRUCache(cache.capacity)
67 def load_extensions(environment, extensions):
68 """Load the extensions from the list and bind it to the environment.
69 Returns a dict of instanciated environments.
72 for extension in extensions:
73 if isinstance(extension, basestring):
74 extension = import_string(extension)
75 result[extension.identifier] = extension(environment)
79 def _environment_sanity_check(environment):
80 """Perform a sanity check on the environment."""
81 assert issubclass(environment.undefined, Undefined), 'undefined must ' \
82 'be a subclass of undefined because filters depend on it.'
83 assert environment.block_start_string != \
84 environment.variable_start_string != \
85 environment.comment_start_string, 'block, variable and comment ' \
86 'start strings must be different'
87 assert environment.newline_sequence in ('\r', '\r\n', '\n'), \
88 'newline_sequence set to unknown line ending string.'
92 class Environment(object):
93 r"""The core component of Jinja is the `Environment`. It contains
94 important shared variables like configuration, filters, tests,
95 globals and others. Instances of this class may be modified if
96 they are not shared and if no template was loaded so far.
97 Modifications on environments after the first template was loaded
98 will lead to surprising effects and undefined behavior.
100 Here the possible initialization parameters:
103 The string marking the begin of a block. Defaults to ``'{%'``.
106 The string marking the end of a block. Defaults to ``'%}'``.
108 `variable_start_string`
109 The string marking the begin of a print statement.
110 Defaults to ``'{{'``.
112 `variable_end_string`
113 The string marking the end of a print statement. Defaults to
116 `comment_start_string`
117 The string marking the begin of a comment. Defaults to ``'{#'``.
120 The string marking the end of a comment. Defaults to ``'#}'``.
122 `line_statement_prefix`
123 If given and a string, this will be used as prefix for line based
124 statements. See also :ref:`line-statements`.
126 `line_comment_prefix`
127 If given and a string, this will be used as prefix for line based
128 based comments. See also :ref:`line-statements`.
130 .. versionadded:: 2.2
133 If this is set to ``True`` the first newline after a block is
134 removed (block, not variable tag!). Defaults to `False`.
137 The sequence that starts a newline. Must be one of ``'\r'``,
138 ``'\n'`` or ``'\r\n'``. The default is ``'\n'`` which is a
139 useful default for Linux and OS X systems as well as web
143 List of Jinja extensions to use. This can either be import paths
144 as strings or extension classes. For more information have a
145 look at :ref:`the extensions documentation <jinja-extensions>`.
148 should the optimizer be enabled? Default is `True`.
151 :class:`Undefined` or a subclass of it that is used to represent
152 undefined values in the template.
155 A callable that can be used to process the result of a variable
156 expression before it is output. For example one can convert
157 `None` implicitly into an empty string here.
160 If set to true the XML/HTML autoescaping feature is enabled.
161 For more details about auto escaping see
162 :class:`~jinja2.utils.Markup`.
165 The template loader for this environment.
168 The size of the cache. Per default this is ``50`` which means
169 that if more than 50 templates are loaded the loader will clean
170 out the least recently used template. If the cache size is set to
171 ``0`` templates are recompiled all the time, if the cache size is
172 ``-1`` the cache will not be cleaned.
175 Some loaders load templates from locations where the template
176 sources may change (ie: file system or database). If
177 `auto_reload` is set to `True` (default) every time a template is
178 requested the loader checks if the source changed and if yes, it
179 will reload the template. For higher performance it's possible to
183 If set to a bytecode cache object, this object will provide a
184 cache for the internal Jinja bytecode so that templates don't
185 have to be parsed if they were not changed.
187 See :ref:`bytecode-cache` for more information.
190 #: if this environment is sandboxed. Modifying this variable won't make
191 #: the environment sandboxed though. For a real sandboxed environment
192 #: have a look at jinja2.sandbox
195 #: True if the environment is just an overlay
198 #: the environment this environment is linked to if it is an overlay
201 #: shared environments have this set to `True`. A shared environment
202 #: must not be modified
205 #: these are currently EXPERIMENTAL undocumented features.
206 exception_handler = None
207 exception_formatter = None
210 block_start_string=BLOCK_START_STRING,
211 block_end_string=BLOCK_END_STRING,
212 variable_start_string=VARIABLE_START_STRING,
213 variable_end_string=VARIABLE_END_STRING,
214 comment_start_string=COMMENT_START_STRING,
215 comment_end_string=COMMENT_END_STRING,
216 line_statement_prefix=LINE_STATEMENT_PREFIX,
217 line_comment_prefix=LINE_COMMENT_PREFIX,
218 trim_blocks=TRIM_BLOCKS,
219 newline_sequence=NEWLINE_SEQUENCE,
228 bytecode_cache=None):
229 # !!Important notice!!
230 # The constructor accepts quite a few arguments that should be
231 # passed by keyword rather than position. However it's important to
232 # not change the order of arguments because it's used at least
233 # internally in those cases:
234 # - spontaneus environments (i18n extension and Template)
236 # If parameter changes are required only add parameters at the end
237 # and don't change the arguments (or the defaults!) of the arguments
240 # lexer / parser information
241 self.block_start_string = block_start_string
242 self.block_end_string = block_end_string
243 self.variable_start_string = variable_start_string
244 self.variable_end_string = variable_end_string
245 self.comment_start_string = comment_start_string
246 self.comment_end_string = comment_end_string
247 self.line_statement_prefix = line_statement_prefix
248 self.line_comment_prefix = line_comment_prefix
249 self.trim_blocks = trim_blocks
250 self.newline_sequence = newline_sequence
252 # runtime information
253 self.undefined = undefined
254 self.optimized = optimized
255 self.finalize = finalize
256 self.autoescape = autoescape
259 self.filters = DEFAULT_FILTERS.copy()
260 self.tests = DEFAULT_TESTS.copy()
261 self.globals = DEFAULT_NAMESPACE.copy()
263 # set the loader provided
265 self.bytecode_cache = None
266 self.cache = create_cache(cache_size)
267 self.bytecode_cache = bytecode_cache
268 self.auto_reload = auto_reload
271 self.extensions = load_extensions(self, extensions)
273 _environment_sanity_check(self)
275 def extend(self, **attributes):
276 """Add the items to the instance of the environment if they do not exist
277 yet. This is used by :ref:`extensions <writing-extensions>` to register
278 callbacks and configuration values without breaking inheritance.
280 for key, value in attributes.iteritems():
281 if not hasattr(self, key):
282 setattr(self, key, value)
284 def overlay(self, block_start_string=missing, block_end_string=missing,
285 variable_start_string=missing, variable_end_string=missing,
286 comment_start_string=missing, comment_end_string=missing,
287 line_statement_prefix=missing, line_comment_prefix=missing,
288 trim_blocks=missing, extensions=missing, optimized=missing,
289 undefined=missing, finalize=missing, autoescape=missing,
290 loader=missing, cache_size=missing, auto_reload=missing,
291 bytecode_cache=missing):
292 """Create a new overlay environment that shares all the data with the
293 current environment except of cache and the overridden attributes.
294 Extensions cannot be removed for an overlayed environment. An overlayed
295 environment automatically gets all the extensions of the environment it
296 is linked to plus optional extra extensions.
298 Creating overlays should happen after the initial environment was set
299 up completely. Not all attributes are truly linked, some are just
300 copied over so modifications on the original environment may not shine
303 args = dict(locals())
304 del args['self'], args['cache_size'], args['extensions']
306 rv = object.__new__(self.__class__)
307 rv.__dict__.update(self.__dict__)
311 for key, value in args.iteritems():
312 if value is not missing:
313 setattr(rv, key, value)
315 if cache_size is not missing:
316 rv.cache = create_cache(cache_size)
318 rv.cache = copy_cache(self.cache)
321 for key, value in self.extensions.iteritems():
322 rv.extensions[key] = value.bind(rv)
323 if extensions is not missing:
324 rv.extensions.update(load_extensions(extensions))
326 return _environment_sanity_check(rv)
328 lexer = property(get_lexer, doc="The lexer for this environment.")
330 def getitem(self, obj, argument):
331 """Get an item or attribute of an object but prefer the item."""
334 except (TypeError, LookupError):
335 if isinstance(argument, basestring):
342 return getattr(obj, attr)
343 except AttributeError:
345 return self.undefined(obj=obj, name=argument)
347 def getattr(self, obj, attribute):
348 """Get an item or attribute of an object but prefer the attribute.
349 Unlike :meth:`getitem` the attribute *must* be a bytestring.
352 return getattr(obj, attribute)
353 except AttributeError:
356 return obj[attribute]
357 except (TypeError, LookupError, AttributeError):
358 return self.undefined(obj=obj, name=attribute)
361 def parse(self, source, name=None, filename=None):
362 """Parse the sourcecode and return the abstract syntax tree. This
363 tree of nodes is used by the compiler to convert the template into
364 executable source- or bytecode. This is useful for debugging or to
365 extract information from templates.
367 If you are :ref:`developing Jinja2 extensions <writing-extensions>`
368 this gives you a good overview of the node tree generated.
371 return self._parse(source, name, filename)
372 except TemplateSyntaxError:
373 exc_info = sys.exc_info()
374 self.handle_exception(exc_info, source_hint=source)
376 def _parse(self, source, name, filename):
377 """Internal parsing function used by `parse` and `compile`."""
378 return Parser(self, source, name, _encode_filename(filename)).parse()
380 def lex(self, source, name=None, filename=None):
381 """Lex the given sourcecode and return a generator that yields
382 tokens as tuples in the form ``(lineno, token_type, value)``.
383 This can be useful for :ref:`extension development <writing-extensions>`
384 and debugging templates.
386 This does not perform preprocessing. If you want the preprocessing
387 of the extensions to be applied you have to filter source through
388 the :meth:`preprocess` method.
390 source = unicode(source)
392 return self.lexer.tokeniter(source, name, filename)
393 except TemplateSyntaxError:
394 exc_info = sys.exc_info()
395 self.handle_exception(exc_info, source_hint=source)
397 def preprocess(self, source, name=None, filename=None):
398 """Preprocesses the source with all extensions. This is automatically
399 called for all parsing and compiling methods but *not* for :meth:`lex`
400 because there you usually only want the actual source tokenized.
402 return reduce(lambda s, e: e.preprocess(s, name, filename),
403 self.extensions.itervalues(), unicode(source))
405 def _tokenize(self, source, name, filename=None, state=None):
406 """Called by the parser to do the preprocessing and filtering
407 for all the extensions. Returns a :class:`~jinja2.lexer.TokenStream`.
409 source = self.preprocess(source, name, filename)
410 stream = self.lexer.tokenize(source, name, filename, state)
411 for ext in self.extensions.itervalues():
412 stream = ext.filter_stream(stream)
413 if not isinstance(stream, TokenStream):
414 stream = TokenStream(stream, name, filename)
418 def compile(self, source, name=None, filename=None, raw=False):
419 """Compile a node or template source code. The `name` parameter is
420 the load name of the template after it was joined using
421 :meth:`join_path` if necessary, not the filename on the file system.
422 the `filename` parameter is the estimated filename of the template on
423 the file system. If the template came from a database or memory this
426 The return value of this method is a python code object. If the `raw`
427 parameter is `True` the return value will be a string with python
428 code equivalent to the bytecode returned otherwise. This method is
429 mainly used internally.
433 if isinstance(source, basestring):
435 source = self._parse(source, name, filename)
437 source = optimize(source, self)
438 source = generate(source, self, name, filename)
442 filename = '<template>'
444 filename = _encode_filename(filename)
445 return compile(source, filename, 'exec')
446 except TemplateSyntaxError:
447 exc_info = sys.exc_info()
448 self.handle_exception(exc_info, source_hint=source)
450 def compile_expression(self, source, undefined_to_none=True):
451 """A handy helper method that returns a callable that accepts keyword
452 arguments that appear as variables in the expression. If called it
453 returns the result of the expression.
455 This is useful if applications want to use the same rules as Jinja
456 in template "configuration files" or similar situations.
460 >>> env = Environment()
461 >>> expr = env.compile_expression('foo == 42')
467 Per default the return value is converted to `None` if the
468 expression returns an undefined value. This can be changed
469 by setting `undefined_to_none` to `False`.
471 >>> env.compile_expression('var')() is None
473 >>> env.compile_expression('var', undefined_to_none=False)()
476 .. versionadded:: 2.1
478 parser = Parser(self, source, state='variable')
481 expr = parser.parse_expression()
482 if not parser.stream.eos:
483 raise TemplateSyntaxError('chunk after expression',
484 parser.stream.current.lineno,
486 except TemplateSyntaxError:
487 exc_info = sys.exc_info()
488 if exc_info is not None:
489 self.handle_exception(exc_info, source_hint=source)
490 body = [nodes.Assign(nodes.Name('result', 'store'), expr, lineno=1)]
491 template = self.from_string(nodes.Template(body, lineno=1))
492 return TemplateExpression(template, undefined_to_none)
494 def handle_exception(self, exc_info=None, rendered=False, source_hint=None):
495 """Exception handling helper. This is used internally to either raise
496 rewritten exceptions or return a rendered traceback for the template.
498 global _make_traceback
500 exc_info = sys.exc_info()
502 # the debugging module is imported when it's used for the first time.
503 # we're doing a lot of stuff there and for applications that do not
504 # get any exceptions in template rendering there is no need to load
506 if _make_traceback is None:
507 from jinja2.debug import make_traceback as _make_traceback
508 traceback = _make_traceback(exc_info, source_hint)
509 if rendered and self.exception_formatter is not None:
510 return self.exception_formatter(traceback)
511 if self.exception_handler is not None:
512 self.exception_handler(traceback)
513 exc_type, exc_value, tb = traceback.standard_exc_info
514 raise exc_type, exc_value, tb
516 def join_path(self, template, parent):
517 """Join a template with the parent. By default all the lookups are
518 relative to the loader root so this method returns the `template`
519 parameter unchanged, but if the paths should be relative to the
520 parent template, this function can be used to calculate the real
523 Subclasses may override this method and implement template path
529 def _load_template(self, name, globals):
530 if self.loader is None:
531 raise TypeError('no loader for this environment specified')
532 if self.cache is not None:
533 template = self.cache.get(name)
534 if template is not None and (not self.auto_reload or \
535 template.is_up_to_date):
537 template = self.loader.load(self, name, globals)
538 if self.cache is not None:
539 self.cache[name] = template
543 def get_template(self, name, parent=None, globals=None):
544 """Load a template from the loader. If a loader is configured this
545 method ask the loader for the template and returns a :class:`Template`.
546 If the `parent` parameter is not `None`, :meth:`join_path` is called
547 to get the real template name before loading.
549 The `globals` parameter can be used to provide template wide globals.
550 These variables are available in the context at render time.
552 If the template does not exist a :exc:`TemplateNotFound` exception is
555 .. versionchanged:: 2.4
556 If `name` is a :class:`Template` object it is returned from the
559 if isinstance(name, Template):
561 if parent is not None:
562 name = self.join_path(name, parent)
563 return self._load_template(name, self.make_globals(globals))
566 def select_template(self, names, parent=None, globals=None):
567 """Works like :meth:`get_template` but tries a number of templates
568 before it fails. If it cannot find any of the templates, it will
569 raise a :exc:`TemplatesNotFound` exception.
571 .. versionadded:: 2.3
573 .. versionchanged:: 2.4
574 If `names` contains a :class:`Template` object it is returned
575 from the function unchanged.
578 raise TemplatesNotFound(message=u'Tried to select from an empty list '
580 globals = self.make_globals(globals)
582 if isinstance(name, Template):
584 if parent is not None:
585 name = self.join_path(name, parent)
587 return self._load_template(name, globals)
588 except TemplateNotFound:
590 raise TemplatesNotFound(names)
593 def get_or_select_template(self, template_name_or_list,
594 parent=None, globals=None):
595 """Does a typecheck and dispatches to :meth:`select_template`
596 if an iterable of template names is given, otherwise to
597 :meth:`get_template`.
599 .. versionadded:: 2.3
601 if isinstance(template_name_or_list, basestring):
602 return self.get_template(template_name_or_list, parent, globals)
603 elif isinstance(template_name_or_list, Template):
604 return template_name_or_list
605 return self.select_template(template_name_or_list, parent, globals)
607 def from_string(self, source, globals=None, template_class=None):
608 """Load a template from a string. This parses the source given and
609 returns a :class:`Template` object.
611 globals = self.make_globals(globals)
612 cls = template_class or self.template_class
613 return cls.from_code(self, self.compile(source), globals, None)
615 def make_globals(self, d):
616 """Return a dict for the globals."""
619 return dict(self.globals, **d)
622 class Template(object):
623 """The central template object. This class represents a compiled template
624 and is used to evaluate it.
626 Normally the template object is generated from an :class:`Environment` but
627 it also has a constructor that makes it possible to create a template
628 instance directly using the constructor. It takes the same arguments as
629 the environment constructor but it's not possible to specify a loader.
631 Every template object has a few methods and members that are guaranteed
632 to exist. However it's important that a template object should be
633 considered immutable. Modifications on the object are not supported.
635 Template objects created from the constructor rather than an environment
636 do have an `environment` attribute that points to a temporary environment
637 that is probably shared with other templates created with the constructor
638 and compatible settings.
640 >>> template = Template('Hello {{ name }}!')
641 >>> template.render(name='John Doe')
644 >>> stream = template.stream(name='John Doe')
648 Traceback (most recent call last):
653 def __new__(cls, source,
654 block_start_string=BLOCK_START_STRING,
655 block_end_string=BLOCK_END_STRING,
656 variable_start_string=VARIABLE_START_STRING,
657 variable_end_string=VARIABLE_END_STRING,
658 comment_start_string=COMMENT_START_STRING,
659 comment_end_string=COMMENT_END_STRING,
660 line_statement_prefix=LINE_STATEMENT_PREFIX,
661 line_comment_prefix=LINE_COMMENT_PREFIX,
662 trim_blocks=TRIM_BLOCKS,
663 newline_sequence=NEWLINE_SEQUENCE,
669 env = get_spontaneous_environment(
670 block_start_string, block_end_string, variable_start_string,
671 variable_end_string, comment_start_string, comment_end_string,
672 line_statement_prefix, line_comment_prefix, trim_blocks,
673 newline_sequence, frozenset(extensions), optimized, undefined,
674 finalize, autoescape, None, 0, False, None)
675 return env.from_string(source, template_class=cls)
678 def from_code(cls, environment, code, globals, uptodate=None):
679 """Creates a template object from compiled code and the globals. This
680 is used by the loaders and environment to create a template object.
682 t = object.__new__(cls)
684 'environment': environment,
685 '__jinja_template__': t
687 exec code in namespace
688 t.environment = environment
690 t.name = namespace['name']
691 t.filename = code.co_filename
692 t.blocks = namespace['blocks']
694 # render function and module
695 t.root_render_func = namespace['root']
698 # debug and loader helpers
699 t._debug_info = namespace['debug_info']
700 t._uptodate = uptodate
704 def render(self, *args, **kwargs):
705 """This method accepts the same arguments as the `dict` constructor:
706 A dict, a dict subclass or some keyword arguments. If no arguments
707 are given the context will be empty. These two calls do the same::
709 template.render(knights='that say nih')
710 template.render({'knights': 'that say nih'})
712 This will return the rendered template as unicode string.
714 vars = dict(*args, **kwargs)
716 return concat(self.root_render_func(self.new_context(vars)))
718 exc_info = sys.exc_info()
719 return self.environment.handle_exception(exc_info, True)
721 def stream(self, *args, **kwargs):
722 """Works exactly like :meth:`generate` but returns a
723 :class:`TemplateStream`.
725 return TemplateStream(self.generate(*args, **kwargs))
727 def generate(self, *args, **kwargs):
728 """For very large templates it can be useful to not render the whole
729 template at once but evaluate each statement after another and yield
730 piece for piece. This method basically does exactly that and returns
731 a generator that yields one item after another as unicode strings.
733 It accepts the same arguments as :meth:`render`.
735 vars = dict(*args, **kwargs)
737 for event in self.root_render_func(self.new_context(vars)):
740 exc_info = sys.exc_info()
743 yield self.environment.handle_exception(exc_info, True)
745 def new_context(self, vars=None, shared=False, locals=None):
746 """Create a new :class:`Context` for this template. The vars
747 provided will be passed to the template. Per default the globals
748 are added to the context. If shared is set to `True` the data
749 is passed as it to the context without adding the globals.
751 `locals` can be a dict of local variables for internal usage.
753 return new_context(self.environment, self.name, self.blocks,
754 vars, shared, self.globals, locals)
756 def make_module(self, vars=None, shared=False, locals=None):
757 """This method works like the :attr:`module` attribute when called
758 without arguments but it will evaluate the template on every call
759 rather than caching it. It's also possible to provide
760 a dict which is then used as context. The arguments are the same
761 as for the :meth:`new_context` method.
763 return TemplateModule(self, self.new_context(vars, shared, locals))
767 """The template as module. This is used for imports in the
768 template runtime but is also useful if one wants to access
769 exported template variables from the Python layer:
771 >>> t = Template('{% macro foo() %}42{% endmacro %}23')
772 >>> unicode(t.module)
777 if self._module is not None:
779 self._module = rv = self.make_module()
782 def get_corresponding_lineno(self, lineno):
783 """Return the source line number of a line number in the
784 generated bytecode as they are not in sync.
786 for template_line, code_line in reversed(self.debug_info):
787 if code_line <= lineno:
792 def is_up_to_date(self):
793 """If this variable is `False` there is a newer version available."""
794 if self._uptodate is None:
796 return self._uptodate()
799 def debug_info(self):
800 """The debug info mapping."""
801 return [tuple(map(int, x.split('='))) for x in
802 self._debug_info.split('&')]
805 if self.name is None:
806 name = 'memory:%x' % id(self)
808 name = repr(self.name)
809 return '<%s %s>' % (self.__class__.__name__, name)
812 class TemplateModule(object):
813 """Represents an imported template. All the exported names of the
814 template are available as attributes on this object. Additionally
815 converting it into an unicode- or bytestrings renders the contents.
818 def __init__(self, template, context):
819 self._body_stream = list(template.root_render_func(context))
820 self.__dict__.update(context.get_exported())
821 self.__name__ = template.name
824 return Markup(concat(self._body_stream))
827 return unicode(self).encode('utf-8')
829 # unicode goes after __str__ because we configured 2to3 to rename
830 # __unicode__ to __str__. because the 2to3 tree is not designed to
831 # remove nodes from it, we leave the above __str__ around and let
832 # it override at runtime.
833 def __unicode__(self):
834 return concat(self._body_stream)
837 if self.__name__ is None:
838 name = 'memory:%x' % id(self)
840 name = repr(self.__name__)
841 return '<%s %s>' % (self.__class__.__name__, name)
844 class TemplateExpression(object):
845 """The :meth:`jinja2.Environment.compile_expression` method returns an
846 instance of this object. It encapsulates the expression-like access
847 to the template with an expression it wraps.
850 def __init__(self, template, undefined_to_none):
851 self._template = template
852 self._undefined_to_none = undefined_to_none
854 def __call__(self, *args, **kwargs):
855 context = self._template.new_context(dict(*args, **kwargs))
856 consume(self._template.root_render_func(context))
857 rv = context.vars['result']
858 if self._undefined_to_none and isinstance(rv, Undefined):
863 class TemplateStream(object):
864 """A template stream works pretty much like an ordinary python generator
865 but it can buffer multiple items to reduce the number of total iterations.
866 Per default the output is unbuffered which means that for every unbuffered
867 instruction in the template one unicode string is yielded.
869 If buffering is enabled with a buffer size of 5, five items are combined
870 into a new unicode string. This is mainly useful if you are streaming
871 big templates to a client via WSGI which flushes after each iteration.
874 def __init__(self, gen):
876 self.disable_buffering()
878 def dump(self, fp, encoding=None, errors='strict'):
879 """Dump the complete stream into a file or file-like object.
880 Per default unicode strings are written, if you want to encode
881 before writing specifiy an `encoding`.
885 Template('Hello {{ name }}!').stream(name='foo').dump('hello.html')
888 if isinstance(fp, basestring):
892 if encoding is not None:
893 iterable = (x.encode(encoding, errors) for x in self)
896 if hasattr(fp, 'writelines'):
897 fp.writelines(iterable)
899 for item in iterable:
905 def disable_buffering(self):
906 """Disable the output buffering."""
907 self._next = self._gen.next
908 self.buffered = False
910 def enable_buffering(self, size=5):
911 """Enable buffering. Buffer `size` items before yielding them."""
913 raise ValueError('buffer size too small')
927 except StopIteration:
935 self._next = generator(self._gen.next).next
944 # hook in default template class. if anyone reads this comment: ignore that
945 # it's possible to use custom templates ;-)
946 Environment.template_class = Template