def __init__(self, file_encoding=None, string_encoding=None,
decode_errors=None, search_dirs=None, file_extension=None,
escape=None, partials=None, to_unicode=None,
literal=None):
"""
Construct an instance.
Arguments:
partials: an object (e.g. a dictionary) for custom partial loading
during the rendering process.
The object should have a get() method that accepts a string
and returns the corresponding template as a string, preferably
as a unicode string. If there is no template with that name,
the get() method should either return None (as dict.get() does)
or raise an exception.
If this argument is None, the rendering process will use
the normal procedure of locating and reading templates from
the file system -- using relevant instance attributes like
search_dirs, file_encoding, etc.
decode_errors: the string to pass as the errors argument to the
built-in function unicode() when converting str strings to
unicode. Defaults to the package default.
escape: the function used to escape variable tag values when
rendering a template. The function should accept a unicode
string (or subclass of unicode) and return an escaped string
that is again unicode (or a subclass of unicode).
This function need not handle strings of type `str` because
this class will only pass it unicode strings. The constructor
assigns this function to the constructed instance's escape()
method.
To disable escaping entirely, one can pass `lambda u: u`
as the escape function, for example. One may also wish to
consider using markupsafe's escape function: markupsafe.escape().
This argument defaults to the package default.
file_encoding: the name of the default encoding to use when reading
template files. All templates are converted to unicode prior
to parsing. This encoding is used when reading template files
and converting them to unicode. Defaults to the package default.
file_extension: the template file extension. Pass False for no
extension (i.e. to use extensionless template files).
Defaults to the package default.
search_dirs: the list of directories in which to search when
loading a template by name or file name. If given a string,
the method interprets the string as a single directory.
Defaults to the package default.
string_encoding: the name of the encoding to use when converting
to unicode any strings of type str encountered during the
rendering process. The name will be passed as the encoding
argument to the built-in function unicode(). Defaults to the
package default.
"""
if decode_errors is None:
decode_errors = defaults.DECODE_ERRORS
if escape is None:
escape = defaults.TAG_ESCAPE
if file_encoding is None:
file_encoding = defaults.FILE_ENCODING
if file_extension is None:
file_extension = defaults.TEMPLATE_EXTENSION
if search_dirs is None:
search_dirs = defaults.SEARCH_DIRS
if string_encoding is None:
string_encoding = defaults.STRING_ENCODING
if isinstance(search_dirs, basestring):
search_dirs = [search_dirs]
if to_unicode is None:
to_unicode = self.unicode
if not literal:
literal = self._to_unicode_hard
self._context = None
self.decode_errors = decode_errors
self._escape = escape
self.file_encoding = file_encoding
self.file_extension = file_extension
self.literal = literal
self.loader = Loader(file_encoding=file_encoding,
extension=file_extension,
to_unicode=to_unicode,
search_dirs=search_dirs)
self.partials = partials
self.search_dirs = search_dirs
self.string_encoding = string_encoding
self.parser = Parser(self)
self.load_partial = self._make_load_partial()
class Renderer(object):
"""
A class for rendering mustache templates.
This class supports several rendering options which are described in
the constructor's docstring. Among these, the constructor supports
passing a custom partial loader.
Here is an example of rendering a template using a custom partial loader
that loads partials from a string-string dictionary.
>>> partials = {'partial': 'Hello, {{thing}}!'}
>>> renderer = Renderer(partials=partials)
>>> # We apply print to make the test work in Python 3 after 2to3.
>>> print renderer.render('{{>partial}}', {'thing': 'world'})
Hello, world!
"""
def __init__(self, file_encoding=None, string_encoding=None,
decode_errors=None, search_dirs=None, file_extension=None,
escape=None, partials=None, to_unicode=None,
literal=None):
"""
Construct an instance.
Arguments:
partials: an object (e.g. a dictionary) for custom partial loading
during the rendering process.
The object should have a get() method that accepts a string
and returns the corresponding template as a string, preferably
as a unicode string. If there is no template with that name,
the get() method should either return None (as dict.get() does)
or raise an exception.
If this argument is None, the rendering process will use
the normal procedure of locating and reading templates from
the file system -- using relevant instance attributes like
search_dirs, file_encoding, etc.
decode_errors: the string to pass as the errors argument to the
built-in function unicode() when converting str strings to
unicode. Defaults to the package default.
escape: the function used to escape variable tag values when
rendering a template. The function should accept a unicode
string (or subclass of unicode) and return an escaped string
that is again unicode (or a subclass of unicode).
This function need not handle strings of type `str` because
this class will only pass it unicode strings. The constructor
assigns this function to the constructed instance's escape()
method.
To disable escaping entirely, one can pass `lambda u: u`
as the escape function, for example. One may also wish to
consider using markupsafe's escape function: markupsafe.escape().
This argument defaults to the package default.
file_encoding: the name of the default encoding to use when reading
template files. All templates are converted to unicode prior
to parsing. This encoding is used when reading template files
and converting them to unicode. Defaults to the package default.
file_extension: the template file extension. Pass False for no
extension (i.e. to use extensionless template files).
Defaults to the package default.
search_dirs: the list of directories in which to search when
loading a template by name or file name. If given a string,
the method interprets the string as a single directory.
Defaults to the package default.
string_encoding: the name of the encoding to use when converting
to unicode any strings of type str encountered during the
rendering process. The name will be passed as the encoding
argument to the built-in function unicode(). Defaults to the
package default.
"""
if decode_errors is None:
decode_errors = defaults.DECODE_ERRORS
if escape is None:
escape = defaults.TAG_ESCAPE
if file_encoding is None:
file_encoding = defaults.FILE_ENCODING
if file_extension is None:
file_extension = defaults.TEMPLATE_EXTENSION
if search_dirs is None:
search_dirs = defaults.SEARCH_DIRS
if string_encoding is None:
string_encoding = defaults.STRING_ENCODING
if isinstance(search_dirs, basestring):
search_dirs = [search_dirs]
if to_unicode is None:
to_unicode = self.unicode
if not literal:
literal = self._to_unicode_hard
self._context = None
self.decode_errors = decode_errors
self._escape = escape
self.file_encoding = file_encoding
self.file_extension = file_extension
self.literal = literal
self.loader = Loader(file_encoding=file_encoding,
extension=file_extension,
to_unicode=to_unicode,
search_dirs=search_dirs)
self.partials = partials
self.search_dirs = search_dirs
self.string_encoding = string_encoding
self.parser = Parser(self)
self.load_partial = self._make_load_partial()
# This is an experimental way of giving views access to the current context.
# TODO: consider another approach of not giving access via a property,
# but instead letting the caller pass the initial context to the
# main render() method by reference. This approach would probably
# be less likely to be misused.
@property
def context(self):
"""
Return the current rendering context [experimental].
"""
return self._context
def escape(self, s):
return self._escape_to_unicode(s)
def _to_unicode_soft(self, s):
"""
Convert a basestring to unicode, preserving any unicode subclass.
"""
# We type-check to avoid "TypeError: decoding Unicode is not supported".
# We avoid the Python ternary operator for Python 2.4 support.
if isinstance(s, unicode):
return s
return self.unicode(s)
def _to_unicode_hard(self, s):
"""
Convert a basestring to a string with type unicode (not subclass).
"""
return unicode(self._to_unicode_soft(s))
def _escape_to_unicode(self, s):
"""
Convert a basestring to unicode (preserving any unicode subclass), and
escape it.
Returns a unicode string (not subclass).
"""
return unicode(self._escape(self._to_unicode_soft(s)))
def unicode(self, b, encoding=None):
"""
Convert a byte string to unicode, using string_encoding and
decode_errors.
Arguments:
b: a byte string.
encoding: the name of an encoding. Defaults to the string_encoding
attribute for this instance.
Raises:
TypeError: Because this method calls Python's built-in unicode()
function, this method raises the following exception if the
given string is already unicode:
TypeError: decoding Unicode is not supported
"""
if encoding is None:
encoding = self.string_encoding
# TODO: Wrap UnicodeDecodeErrors with a message about setting
# the string_encoding and decode_errors attributes.
return unicode(b, encoding, self.decode_errors)
def _make_load_partial(self):
"""
Return the load_partial function.
"""
if self.partials is None:
return self.loader.load_name
# Otherwise, create a load_partial function from the custom partial
# loader that satisfies Render requirements (and that provides
# a nicer exception, etc).
partials = self.partials
def load_partial(name):
template = partials.get(name)
if template is None:
raise TemplateNotFoundError(
"Name %s not found in partials: %s" %
(repr(name), type(partials)))
# RenderEngine requires that the return value be unicode.
return self._to_unicode_hard(template)
return load_partial
# TODO: add unit tests for this method.
def load_template(self, template_name):
"""
Load a template by name from the file system.
"""
return self.loader.load_name(template_name)
def _render_string(self, template, *context, **kwargs):
"""
Render the given template string using the given context.
"""
# RenderEngine.render() requires that the template string be unicode.
template = self._to_unicode_hard(template)
context = ContextStack.create(*context, **kwargs)
self._context = context
# We keep this type-check as an added check because this method is
# called with template strings coming from potentially externally-
# supplied functions like self.literal, self.load_partial, etc.
# Beyond this point, we have much better control over the type.
if type(template) is not unicode:
raise Exception("Argument 'template' not unicode: %s: %s" % (
type(template), repr(template)))
parsed_template = self.parser.parse(template=template)
rendered = parsed_template.render(context)
return unicode(rendered)
def _render_object(self, obj, *context, **kwargs):
"""
Render the template associated with the given object.
"""
loader = self.loader
# TODO: consider an approach that does not require using an if
# block here. For example, perhaps this class's loader can be
# a SpecLoader in all cases, and the SpecLoader instance can
# check the object's type. Or perhaps Loader and SpecLoader
# can be refactored to implement the same interface.
if isinstance(obj, TemplateSpec):
loader = SpecLoader(loader)
template = loader.load(obj)
else:
template = loader.load_object(obj)
context = [obj] + list(context)
return self._render_string(template, *context, **kwargs)
def render_path(self, template_path, *context, **kwargs):
"""
Render the template at the given path using the given context.
Read the render() docstring for more information.
"""
loader = self.loader
template = loader.read(template_path)
return self._render_string(template, *context, **kwargs)
def render(self, template, *context, **kwargs):
"""
Render the given template (or template object) using the given context.
Returns the rendering as a unicode string.
Prior to rendering, templates of type str are converted to unicode
using the string_encoding and decode_errors attributes. See the
constructor docstring for more information.
Arguments:
template: a template string of type unicode or str, or an object
instance. If the argument is an object, the function first looks
for the template associated to the object by calling this class's
get_associated_template() method. The rendering process also
uses the passed object as the first element of the context stack
when rendering.
*context: zero or more dictionaries, ContextStack instances, or objects
with which to populate the initial context stack. None
arguments are skipped. Items in the *context list are added to
the context stack in order so that later items in the argument
list take precedence over earlier items.
**kwargs: additional key-value data to add to the context stack.
As these arguments appear after all items in the *context list,
in the case of key conflicts these values take precedence over
all items in the *context list.
"""
if isinstance(template, _STRING_TYPES):
return self._render_string(template, *context, **kwargs)
# Otherwise, we assume the template is an object.
return self._render_object(template, *context, **kwargs)
