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# mako/runtime.py
# Copyright (C) 2006-2011 the Mako authors and contributors <see AUTHORS file>
#
# This module is part of Mako and is released under
# the MIT License: http://www.opensource.org/licenses/mit-license.php
"""provides runtime services for templates, including Context,
Namespace, and various helper functions."""
from mako import exceptions, util
import __builtin__, inspect, sys
class Context(object):
"""Provides runtime namespace, output buffer, and various
callstacks for templates.
See :ref:`runtime_toplevel` for detail on the usage of
:class:`.Context`.
"""
def __init__(self, buffer, **data):
self._buffer_stack = [buffer]
self._data = data
self._kwargs = data.copy()
self._with_template = None
self._outputting_as_unicode = None
self.namespaces = {}
# "capture" function which proxies to the
# generic "capture" function
self._data['capture'] = util.partial(capture, self)
# "caller" stack used by def calls with content
self.caller_stack = self._data['caller'] = CallerStack()
@property
def lookup(self):
"""Return the :class:`.TemplateLookup` associated
with this :class:`.Context`.
"""
return self._with_template.lookup
@property
def kwargs(self):
"""Return the dictionary of keyword argments associated with this
:class:`.Context`.
"""
return self._kwargs.copy()
def push_caller(self, caller):
"""Pushes a 'caller' callable onto the callstack for
this :class:`.Context`."""
self.caller_stack.append(caller)
def pop_caller(self):
"""Pops a 'caller' callable onto the callstack for this
:class:`.Context`."""
del self.caller_stack[-1]
def keys(self):
"""Return a list of all names established in this :class:`.Context`."""
return self._data.keys()
def __getitem__(self, key):
if key in self._data:
return self._data[key]
else:
return __builtin__.__dict__[key]
def _push_writer(self):
"""push a capturing buffer onto this Context and return
the new writer function."""
buf = util.FastEncodingBuffer()
self._buffer_stack.append(buf)
return buf.write
def _pop_buffer_and_writer(self):
"""pop the most recent capturing buffer from this Context
and return the current writer after the pop.
"""
buf = self._buffer_stack.pop()
return buf, self._buffer_stack[-1].write
def _push_buffer(self):
"""push a capturing buffer onto this Context."""
self._push_writer()
def _pop_buffer(self):
"""pop the most recent capturing buffer from this Context."""
return self._buffer_stack.pop()
def get(self, key, default=None):
"""Return a value from this :class:`.Context`."""
return self._data.get(key,
__builtin__.__dict__.get(key, default)
)
def write(self, string):
"""Write a string to this :class:`.Context` object's
underlying output buffer."""
self._buffer_stack[-1].write(string)
def writer(self):
"""Return the current writer function"""
return self._buffer_stack[-1].write
def _copy(self):
c = Context.__new__(Context)
c._buffer_stack = self._buffer_stack
c._data = self._data.copy()
c._kwargs = self._kwargs
c._with_template = self._with_template
c._outputting_as_unicode = self._outputting_as_unicode
c.namespaces = self.namespaces
c.caller_stack = self.caller_stack
return c
def locals_(self, d):
"""create a new :class:`.Context` with a copy of this
:class:`Context`'s current state, updated with the given dictionary."""
if len(d) == 0:
return self
c = self._copy()
c._data.update(d)
return c
def _clean_inheritance_tokens(self):
"""create a new copy of this :class:`.Context`. with
tokens related to inheritance state removed."""
c = self._copy()
x = c._data
x.pop('self', None)
x.pop('parent', None)
x.pop('next', None)
return c
class CallerStack(list):
def __init__(self):
self.nextcaller = None
def __nonzero__(self):
return self._get_caller() and True or False
def _get_caller(self):
return self[-1]
def __getattr__(self, key):
return getattr(self._get_caller(), key)
def _push_frame(self):
self.append(self.nextcaller or None)
self.nextcaller = None
def _pop_frame(self):
self.nextcaller = self.pop()
class Undefined(object):
"""Represents an undefined value in a template.
All template modules have a constant value
``UNDEFINED`` present which is an instance of this
object.
"""
def __str__(self):
raise NameError("Undefined")
def __nonzero__(self):
return False
UNDEFINED = Undefined()
class _NSAttr(object):
def __init__(self, parent):
self.__parent = parent
def __getattr__(self, key):
ns = self.__parent
while ns:
if hasattr(ns.module, key):
return getattr(ns.module, key)
else:
ns = ns.inherits
raise AttributeError(key)
class Namespace(object):
"""Provides access to collections of rendering methods, which
can be local, from other templates, or from imported modules.
To access a particular rendering method referenced by a
:class:`.Namespace`, use plain attribute access::
${some_namespace.foo(x, y, z)}
:class:`.Namespace` also contains several built-in attributes
described here.
"""
def __init__(self, name, context,
callables=None, inherits=None,
populate_self=True, calling_uri=None):
self.name = name
self.context = context
self.inherits = inherits
if callables is not None:
self.callables = dict([(c.func_name, c) for c in callables])
callables = ()
module = None
"""The Python module referenced by this Namespace.
If the namespace references a :class:`.Template`, then
this module is the equivalent of ``template.module``,
i.e. the generated module for the template.
"""
template = None
"""The :class:`.Template` object referenced by this
:class:`.Namespace`, if any.
"""
context = None
"""The :class:`.Context` object for this namespace.
Namespaces are often created with copies of contexts that
contain slightly different data, particularly in inheritance
scenarios. Using the :class:`.Context` off of a :class:`.Namespace` one
can traverse an entire chain of templates that inherit from
one-another.
"""
filename = None
"""The path of the filesystem file used for this
Namespace's module or template.
If this is a pure module-based
Namespace, this evaluates to ``module.__file__``. If a
template-based namespace, it evaluates to the original
template file location.
"""
uri = None
"""The uri for this Namespace's template.
I.e. whatever was sent to :meth:`.TemplateLookup.get_template()`.
This is the equivalent of :attr:`Template.uri`.
"""
_templateuri = None
@util.memoized_property
def attr(self):
"""Access module level attributes by name.
This accessor allows templates to supply "scalar"
attributes which are particularly handy in inheritance
relationships. See the example in
:ref:`inheritance_toplevel`.
"""
return _NSAttr(self)
def get_namespace(self, uri):
"""Return a :class:`.Namespace` corresponding to the given uri.
If the given uri is a relative uri (i.e. it does not
contain ia leading slash ``/``), the uri is adjusted to
be relative to the uri of the namespace itself. This
method is therefore mostly useful off of the built-in
``local`` namespace, described in :ref:`namespace_local`
In
most cases, a template wouldn't need this function, and
should instead use the ``<%namespace>`` tag to load
namespaces. However, since all ``<%namespace>`` tags are
evaulated before the body of a template ever runs,
this method can be used to locate namespaces using
expressions that were generated within the body code of
the template, or to conditionally use a particular
namespace.
"""
key = (self, uri)
if key in self.context.namespaces:
return self.context.namespaces[key]
else:
ns = TemplateNamespace(uri, self.context._copy(),
templateuri=uri,
calling_uri=self._templateuri)
self.context.namespaces[key] = ns
return ns
def get_template(self, uri):
"""Return a :class:`.Template` from the given uri.
The uri resolution is relative to the uri of this :class:`.Namespace`
object's :class:`.Template`.
"""
return _lookup_template(self.context, uri, self._templateuri)
def get_cached(self, key, **kwargs):
"""Return a value from the :class:`.Cache` referenced by this
:class:`.Namespace` object's :class:`.Template`.
The advantage to this method versus direct access to the
:class:`.Cache` is that the configuration parameters
declared in ``<%page>`` take effect here, thereby calling
up the same configured backend as that configured
by ``<%page>``.
"""
if self.template:
if not self.template.cache_enabled:
createfunc = kwargs.get('createfunc', None)
if createfunc:
return createfunc()
else:
return None
if self.template.cache_dir:
kwargs.setdefault('data_dir', self.template.cache_dir)
if self.template.cache_type:
kwargs.setdefault('type', self.template.cache_type)
if self.template.cache_url:
kwargs.setdefault('url', self.template.cache_url)
return self.cache.get(key, **kwargs)
@property
def cache(self):
"""Return the :class:`.Cache` object referenced
by this :class:`.Namespace` object's
:class:`.Template`.
"""
return self.template.cache
def include_file(self, uri, **kwargs):
"""Include a file at the given uri"""
_include_file(self.context, uri, self._templateuri, **kwargs)
def _populate(self, d, l):
for ident in l:
if ident == '*':
for (k, v) in self._get_star():
d[k] = v
else:
d[ident] = getattr(self, ident)
def _get_star(self):
if self.callables:
for key in self.callables:
yield (key, self.callables[key])
def __getattr__(self, key):
if key in self.callables:
val = self.callables[key]
elif self.inherits:
val = getattr(self.inherits, key)
else:
raise AttributeError(
"Namespace '%s' has no member '%s'" %
(self.name, key))
setattr(self, key, val)
return val
class TemplateNamespace(Namespace):
"""A :class:`.Namespace` specific to a :class:`.Template` instance."""
def __init__(self, name, context, template=None, templateuri=None,
callables=None, inherits=None,
populate_self=True, calling_uri=None):
self.name = name
self.context = context
self.inherits = inherits
if callables is not None:
self.callables = dict([(c.func_name, c) for c in callables])
if templateuri is not None:
self.template = _lookup_template(context, templateuri,
calling_uri)
self._templateuri = self.template.module._template_uri
elif template is not None:
self.template = template
self._templateuri = template.module._template_uri
else:
raise TypeError("'template' argument is required.")
if populate_self:
lclcallable, lclcontext = \
_populate_self_namespace(context, self.template,
self_ns=self)
@property
def module(self):
"""The Python module referenced by this Namespace.
If the namespace references a :class:`.Template`, then
this module is the equivalent of ``template.module``,
i.e. the generated module for the template.
"""
return self.template.module
@property
def filename(self):
"""The path of the filesystem file used for this
Namespace's module or template.
"""
return self.template.filename
@property
def uri(self):
"""The uri for this Namespace's template.
I.e. whatever was sent to :meth:`.TemplateLookup.get_template()`.
This is the equivalent of :attr:`Template.uri`.
"""
return self.template.uri
def _get_star(self):
if self.callables:
for key in self.callables:
yield (key, self.callables[key])
def get(key):
callable_ = self.template._get_def_callable(key)
return util.partial(callable_, self.context)
for k in self.template.module._exports:
yield (k, get(k))
def __getattr__(self, key):
if key in self.callables:
val = self.callables[key]
elif self.template.has_def(key):
callable_ = self.template._get_def_callable(key)
val = util.partial(callable_, self.context)
elif self.inherits:
val = getattr(self.inherits, key)
else:
raise AttributeError(
"Namespace '%s' has no member '%s'" %
(self.name, key))
setattr(self, key, val)
return val
class ModuleNamespace(Namespace):
"""A :class:`.Namespace` specific to a Python module instance."""
def __init__(self, name, context, module,
callables=None, inherits=None,
populate_self=True, calling_uri=None):
self.name = name
self.context = context
self.inherits = inherits
if callables is not None:
self.callables = dict([(c.func_name, c) for c in callables])
mod = __import__(module)
for token in module.split('.')[1:]:
mod = getattr(mod, token)
self.module = mod
@property
def filename(self):
"""The path of the filesystem file used for this
Namespace's module or template.
"""
return self.module.__file__
def _get_star(self):
if self.callables:
for key in self.callables:
yield (key, self.callables[key])
def get(key):
callable_ = getattr(self.module, key)
return util.partial(callable_, self.context)
for k in dir(self.module):
if k[0] != '_':
yield (k, get(k))
def __getattr__(self, key):
if key in self.callables:
val = self.callables[key]
elif hasattr(self.module, key):
callable_ = getattr(self.module, key)
val = util.partial(callable_, self.context)
elif self.inherits:
val = getattr(self.inherits, key)
else:
raise AttributeError(
"Namespace '%s' has no member '%s'" %
(self.name, key))
setattr(self, key, val)
return val
def supports_caller(func):
"""Apply a caller_stack compatibility decorator to a plain
Python function.
See the example in :ref:`namespaces_python_modules`.
"""
def wrap_stackframe(context, *args, **kwargs):
context.caller_stack._push_frame()
try:
return func(context, *args, **kwargs)
finally:
context.caller_stack._pop_frame()
return wrap_stackframe
def capture(context, callable_, *args, **kwargs):
"""Execute the given template def, capturing the output into
a buffer.
See the example in :ref:`namespaces_python_modules`.
"""
if not callable(callable_):
raise exceptions.RuntimeException(
"capture() function expects a callable as "
"its argument (i.e. capture(func, *args, **kwargs))"
)
context._push_buffer()
try:
callable_(*args, **kwargs)
finally:
buf = context._pop_buffer()
return buf.getvalue()
def _decorate_toplevel(fn):
def decorate_render(render_fn):
def go(context, *args, **kw):
def y(*args, **kw):
return render_fn(context, *args, **kw)
try:
y.__name__ = render_fn.__name__[7:]
except TypeError:
# < Python 2.4
pass
return fn(y)(context, *args, **kw)
return go
return decorate_render
def _decorate_inline(context, fn):
def decorate_render(render_fn):
dec = fn(render_fn)
def go(*args, **kw):
return dec(context, *args, **kw)
return go
return decorate_render
def _include_file(context, uri, calling_uri, **kwargs):
"""locate the template from the given uri and include it in
the current output."""
template = _lookup_template(context, uri, calling_uri)
(callable_, ctx) = _populate_self_namespace(
context._clean_inheritance_tokens(),
template)
callable_(ctx, **_kwargs_for_include(callable_, context._data, **kwargs))
def _inherit_from(context, uri, calling_uri):
"""called by the _inherit method in template modules to set
up the inheritance chain at the start of a template's
execution."""
if uri is None:
return None
template = _lookup_template(context, uri, calling_uri)
self_ns = context['self']
ih = self_ns
while ih.inherits is not None:
ih = ih.inherits
lclcontext = context.locals_({'next':ih})
ih.inherits = TemplateNamespace("self:%s" % template.uri,
lclcontext,
template = template,
populate_self=False)
context._data['parent'] = lclcontext._data['local'] = ih.inherits
callable_ = getattr(template.module, '_mako_inherit', None)
if callable_ is not None:
ret = callable_(template, lclcontext)
if ret:
return ret
gen_ns = getattr(template.module, '_mako_generate_namespaces', None)
if gen_ns is not None:
gen_ns(context)
return (template.callable_, lclcontext)
def _lookup_template(context, uri, relativeto):
lookup = context._with_template.lookup
if lookup is None:
raise exceptions.TemplateLookupException(
"Template '%s' has no TemplateLookup associated" %
context._with_template.uri)
uri = lookup.adjust_uri(uri, relativeto)
try:
return lookup.get_template(uri)
except exceptions.TopLevelLookupException, e:
raise exceptions.TemplateLookupException(str(e))
def _populate_self_namespace(context, template, self_ns=None):
if self_ns is None:
self_ns = TemplateNamespace('self:%s' % template.uri,
context, template=template,
populate_self=False)
context._data['self'] = context._data['local'] = self_ns
if hasattr(template.module, '_mako_inherit'):
ret = template.module._mako_inherit(template, context)
if ret:
return ret
return (template.callable_, context)
def _render(template, callable_, args, data, as_unicode=False):
"""create a Context and return the string
output of the given template and template callable."""
if as_unicode:
buf = util.FastEncodingBuffer(unicode=True)
elif template.bytestring_passthrough:
buf = util.StringIO()
else:
buf = util.FastEncodingBuffer(
unicode=as_unicode,
encoding=template.output_encoding,
errors=template.encoding_errors)
context = Context(buf, **data)
context._outputting_as_unicode = as_unicode
context._with_template = template
_render_context(template, callable_, context, *args,
**_kwargs_for_callable(callable_, data))
return context._pop_buffer().getvalue()
def _kwargs_for_callable(callable_, data):
argspec = util.inspect_func_args(callable_)
# for normal pages, **pageargs is usually present
if argspec[2]:
return data
# for rendering defs from the top level, figure out the args
namedargs = argspec[0] + [v for v in argspec[1:3] if v is not None]
kwargs = {}
for arg in namedargs:
if arg != 'context' and arg in data and arg not in kwargs:
kwargs[arg] = data[arg]
return kwargs
def _kwargs_for_include(callable_, data, **kwargs):
argspec = util.inspect_func_args(callable_)
namedargs = argspec[0] + [v for v in argspec[1:3] if v is not None]
for arg in namedargs:
if arg != 'context' and arg in data and arg not in kwargs:
kwargs[arg] = data[arg]
return kwargs
def _render_context(tmpl, callable_, context, *args, **kwargs):
import mako.template as template
# create polymorphic 'self' namespace for this
# template with possibly updated context
if not isinstance(tmpl, template.DefTemplate):
# if main render method, call from the base of the inheritance stack
(inherit, lclcontext) = _populate_self_namespace(context, tmpl)
_exec_template(inherit, lclcontext, args=args, kwargs=kwargs)
else:
# otherwise, call the actual rendering method specified
(inherit, lclcontext) = _populate_self_namespace(context, tmpl.parent)
_exec_template(callable_, context, args=args, kwargs=kwargs)
def _exec_template(callable_, context, args=None, kwargs=None):
"""execute a rendering callable given the callable, a
Context, and optional explicit arguments
the contextual Template will be located if it exists, and
the error handling options specified on that Template will
be interpreted here.
"""
template = context._with_template
if template is not None and \
(template.format_exceptions or template.error_handler):
error = None
try:
callable_(context, *args, **kwargs)
except Exception, e:
_render_error(template, context, e)
except:
e = sys.exc_info()[0]
_render_error(template, context, e)
else:
callable_(context, *args, **kwargs)
def _render_error(template, context, error):
if template.error_handler:
result = template.error_handler(context, error)
if not result:
raise error
else:
error_template = exceptions.html_error_template()
if context._outputting_as_unicode:
context._buffer_stack[:] = [util.FastEncodingBuffer(unicode=True)]
else:
context._buffer_stack[:] = [util.FastEncodingBuffer(
error_template.output_encoding,
error_template.encoding_errors)]
context._with_template = error_template
error_template.render_context(context, error=error)
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