# runtime.py
# Copyright (C) 2006, 2007, 2008, 2009, 2010 Michael Bayer mike_mp@zzzcomputing.com
#
# 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."""
def __init__(self, buffer, **data):
self._buffer_stack = [buffer]
self._orig = data # original data, minus the builtins
self._data = __builtin__.__dict__.copy() # the context data which includes builtins
self._data.update(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'] = lambda x, *args, **kwargs: capture(self, x, *args, **kwargs)
# "caller" stack used by def calls with content
self.caller_stack = self._data['caller'] = CallerStack()
@property
def lookup(self):
return self._with_template.lookup
@property
def kwargs(self):
return self._kwargs.copy()
def push_caller(self, caller):
self.caller_stack.append(caller)
def pop_caller(self):
del self.caller_stack[-1]
def keys(self):
return self._data.keys()
def __getitem__(self, key):
return self._data[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 self._data.get(key, default)
def write(self, string):
"""write a string to this Context'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._orig = self._orig
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 Context with a copy of this 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 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."""
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"""
def __init__(self, name, context, module=None,
template=None, templateuri=None,
callables=None, inherits=None,
populate_self=True, calling_uri=None):
self.name = name
if module is not None:
mod = __import__(module)
for token in module.split('.')[1:]:
mod = getattr(mod, token)
self._module = mod
else:
self._module = None
if templateuri is not None:
self.template = _lookup_template(context, templateuri, calling_uri)
self._templateuri = self.template.module._template_uri
else:
self.template = template
if self.template is not None:
self._templateuri = self.template.module._template_uri
self.context = context
self.inherits = inherits
if callables is not None:
self.callables = dict([(c.func_name, c) for c in callables])
else:
self.callables = None
if populate_self and self.template is not None:
(lclcallable, lclcontext) = _populate_self_namespace(context, self.template, self_ns=self)
@property
def module(self):
return self._module or self.template.module
@property
def filename(self):
if self._module:
return self._module.__file__
else:
return self.template.filename
@property
def uri(self):
return self.template.uri
@property
def attr(self):
if not hasattr(self, '_attr'):
self._attr = _NSAttr(self)
return self._attr
def get_namespace(self, uri):
"""return a namespace corresponding to the given template uri.
if a relative uri, it is adjusted to that of the template of this namespace"""
key = (self, uri)
if self.context.namespaces.has_key(key):
return self.context.namespaces[key]
else:
ns = Namespace(uri, self.context._copy(), templateuri=uri, calling_uri=self._templateuri)
self.context.namespaces[key] = ns
return ns
def get_template(self, uri):
return _lookup_template(self.context, uri, self._templateuri)
def get_cached(self, key, **kwargs):
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 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])
if self.template:
def get(key):
callable_ = self.template._get_def_callable(key)
return lambda *args, **kwargs:callable_(self.context, *args, **kwargs)
for k in self.template.module._exports:
yield (k, get(k))
if self._module:
def get(key):
callable_ = getattr(self._module, key)
return lambda *args, **kwargs:callable_(self.context, *args, **kwargs)
for k in dir(self._module):
if k[0] != '_':
yield (k, get(k))
def __getattr__(self, key):
if self.callables and key in self.callables:
return self.callables[key]
if self.template and self.template.has_def(key):
callable_ = self.template._get_def_callable(key)
return lambda *args, **kwargs:callable_(self.context, *args, **kwargs)
if self._module and hasattr(self._module, key):
callable_ = getattr(self._module, key)
return lambda *args, **kwargs:callable_(self.context, *args, **kwargs)
if self.inherits is not None:
return getattr(self.inherits, key)
raise AttributeError("Namespace '%s' has no member '%s'" % (self.name, key))
def supports_caller(func):
"""apply a caller_stack compatibility decorator to a plain Python function."""
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."""
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._orig, **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 = Namespace("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 = Namespace('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.output_encoding:
buf = util.FastEncodingBuffer(
unicode=as_unicode,
encoding=template.output_encoding,
errors=template.encoding_errors)
else:
buf = util.StringIO()
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 = inspect.getargspec(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 = inspect.getargspec(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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