Adding pystache to third_party

BUG=734131, 734136

Review-Url: https://codereview.chromium.org/2962783004
Cr-Commit-Position: refs/heads/master@{#488641}

third_party/pystache/LICENSE

+Copyright (C) 2012 Chris Jerdonek.  All rights reserved.
+
+Copyright (c) 2009 Chris Wanstrath
+
+Permission is hereby granted, free of charge, to any person obtaining
+a copy of this software and associated documentation files (the
+"Software"), to deal in the Software without restriction, including
+without limitation the rights to use, copy, modify, merge, publish,
+distribute, sublicense, and/or sell copies of the Software, and to
+permit persons to whom the Software is furnished to do so, subject to
+the following conditions:
+
+The above copyright notice and this permission notice shall be
+included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

third_party/pystache/OWNERS

+hanxi@chromium.org
+pkotwicz@chromium.org
+yfriedman@chromium.org

third_party/pystache/README.chromium

+Name: Pystache, a Python implementation of Mustache templates
+Short Name: Pystache
+URL: https://github.com/defunkt/pystache
+Version: 0.5.4
+Date: June 28, 2017
+Revision: commit 17a5dfdcd56eb76af731d141de395a7632a905b8
+License: MIT
+License File: NOT_SHIPPED
+Security Critical: No
+
+Description:
+Pystache is a Python implementation of Mustache. Mustache is a
+framework-agnostic, logic-free templating system.
+
+Local Modifications: None

third_party/pystache/src/__init__.py

+
+"""
+TODO: add a docstring.
+
+"""
+
+# We keep all initialization code in a separate module.
+
+from pystache.init import parse, render, Renderer, TemplateSpec
+
+__all__ = ['parse', 'render', 'Renderer', 'TemplateSpec']
+
+__version__ = '0.5.4'  # Also change in setup.py.

third_party/pystache/src/common.py

+# coding: utf-8
+
+"""
+Exposes functionality needed throughout the project.
+
+"""
+
+from sys import version_info
+
+def _get_string_types():
+    # TODO: come up with a better solution for this.  One of the issues here
+    #   is that in Python 3 there is no common base class for unicode strings
+    #   and byte strings, and 2to3 seems to convert all of "str", "unicode",
+    #   and "basestring" to Python 3's "str".
+    if version_info < (3, ):
+         return basestring
+    # The latter evaluates to "bytes" in Python 3 -- even after conversion by 2to3.
+    return (unicode, type(u"a".encode('utf-8')))
+
+
+_STRING_TYPES = _get_string_types()
+
+
+def is_string(obj):
+    """
+    Return whether the given object is a byte string or unicode string.
+
+    This function is provided for compatibility with both Python 2 and 3
+    when using 2to3.
+
+    """
+    return isinstance(obj, _STRING_TYPES)
+
+
+# This function was designed to be portable across Python versions -- both
+# with older versions and with Python 3 after applying 2to3.
+def read(path):
+    """
+    Return the contents of a text file as a byte string.
+
+    """
+    # Opening in binary mode is necessary for compatibility across Python
+    # 2 and 3.  In both Python 2 and 3, open() defaults to opening files in
+    # text mode.  However, in Python 2, open() returns file objects whose
+    # read() method returns byte strings (strings of type `str` in Python 2),
+    # whereas in Python 3, the file object returns unicode strings (strings
+    # of type `str` in Python 3).
+    f = open(path, 'rb')
+    # We avoid use of the with keyword for Python 2.4 support.
+    try:
+        return f.read()
+    finally:
+        f.close()
+
+
+class MissingTags(object):
+
+    """Contains the valid values for Renderer.missing_tags."""
+
+    ignore = 'ignore'
+    strict = 'strict'
+
+
+class PystacheError(Exception):
+    """Base class for Pystache exceptions."""
+    pass
+
+
+class TemplateNotFoundError(PystacheError):
+    """An exception raised when a template is not found."""
+    pass

third_party/pystache/src/defaults.py

+# coding: utf-8
+
+"""
+This module provides a central location for defining default behavior.
+
+Throughout the package, these defaults take effect only when the user
+does not otherwise specify a value.
+
+"""
+
+try:
+    # Python 3.2 adds html.escape() and deprecates cgi.escape().
+    from html import escape
+except ImportError:
+    from cgi import escape
+
+import os
+import sys
+
+from pystache.common import MissingTags
+
+
+# How to handle encoding errors when decoding strings from str to unicode.
+#
+# This value is passed as the "errors" argument to Python's built-in
+# unicode() function:
+#
+#   http://docs.python.org/library/functions.html#unicode
+#
+DECODE_ERRORS = 'strict'
+
+# The name of the encoding to use when converting to unicode any strings of
+# type str encountered during the rendering process.
+STRING_ENCODING = sys.getdefaultencoding()
+
+# The name of the encoding to use when converting file contents to unicode.
+# This default takes precedence over the STRING_ENCODING default for
+# strings that arise from files.
+FILE_ENCODING = sys.getdefaultencoding()
+
+# The delimiters to start with when parsing.
+DELIMITERS = (u'{{', u'}}')
+
+# How to handle missing tags when rendering a template.
+MISSING_TAGS = MissingTags.ignore
+
+# The starting list of directories in which to search for templates when
+# loading a template by file name.
+SEARCH_DIRS = [os.curdir]  # i.e. ['.']
+
+# The escape function to apply to strings that require escaping when
+# rendering templates (e.g. for tags enclosed in double braces).
+# Only unicode strings will be passed to this function.
+#
+# The quote=True argument causes double but not single quotes to be escaped
+# in Python 3.1 and earlier, and both double and single quotes to be
+# escaped in Python 3.2 and later:
+#
+#   http://docs.python.org/library/cgi.html#cgi.escape
+#   http://docs.python.org/dev/library/html.html#html.escape
+#
+TAG_ESCAPE = lambda u: escape(u, quote=True)
+
+# The default template extension, without the leading dot.
+TEMPLATE_EXTENSION = 'mustache'

third_party/pystache/src/init.py

+# encoding: utf-8
+
+"""
+This module contains the initialization logic called by __init__.py.
+
+"""
+
+from pystache.parser import parse
+from pystache.renderer import Renderer
+from pystache.template_spec import TemplateSpec
+
+
+def render(template, context=None, **kwargs):
+    """
+    Return the given template string rendered using the given context.
+
+    """
+    renderer = Renderer()
+    return renderer.render(template, context, **kwargs)

third_party/pystache/src/loader.py

+# coding: utf-8
+
+"""
+This module provides a Loader class for locating and reading templates.
+
+"""
+
+import os
+import sys
+
+from pystache import common
+from pystache import defaults
+from pystache.locator import Locator
+
+
+# We make a function so that the current defaults take effect.
+# TODO: revisit whether this is necessary.
+
+def _make_to_unicode():
+    def to_unicode(s, encoding=None):
+        """
+        Raises a TypeError exception if the given string is already unicode.
+
+        """
+        if encoding is None:
+            encoding = defaults.STRING_ENCODING
+        return unicode(s, encoding, defaults.DECODE_ERRORS)
+    return to_unicode
+
+
+class Loader(object):
+
+    """
+    Loads the template associated to a name or user-defined object.
+
+    All load_*() methods return the template as a unicode string.
+
+    """
+
+    def __init__(self, file_encoding=None, extension=None, to_unicode=None,
+                 search_dirs=None):
+        """
+        Construct a template loader instance.
+
+        Arguments:
+
+          extension: the template file extension, without the leading dot.
+            Pass False for no extension (e.g. to use extensionless template
+            files).  Defaults to the package default.
+
+          file_encoding: the name of the encoding to use when converting file
+            contents to unicode.  Defaults to the package default.
+
+          search_dirs: the list of directories in which to search when loading
+            a template by name or file name.  Defaults to the package default.
+
+          to_unicode: the function to use when converting strings of type
+            str to unicode.  The function should have the signature:
+
+              to_unicode(s, encoding=None)
+
+            It should accept a string of type str and an optional encoding
+            name and return a string of type unicode.  Defaults to calling
+            Python's built-in function unicode() using the package string
+            encoding and decode errors defaults.
+
+        """
+        if extension is None:
+            extension = defaults.TEMPLATE_EXTENSION
+
+        if file_encoding is None:
+            file_encoding = defaults.FILE_ENCODING
+
+        if search_dirs is None:
+            search_dirs = defaults.SEARCH_DIRS
+
+        if to_unicode is None:
+            to_unicode = _make_to_unicode()
+
+        self.extension = extension
+        self.file_encoding = file_encoding
+        # TODO: unit test setting this attribute.
+        self.search_dirs = search_dirs
+        self.to_unicode = to_unicode
+
+    def _make_locator(self):
+        return Locator(extension=self.extension)
+
+    def unicode(self, s, encoding=None):
+        """
+        Convert a string to unicode using the given encoding, and return it.
+
+        This function uses the underlying to_unicode attribute.
+
+        Arguments:
+
+          s: a basestring instance to convert to unicode.  Unlike Python's
+            built-in unicode() function, it is okay to pass unicode strings
+            to this function.  (Passing a unicode string to Python's unicode()
+            with the encoding argument throws the error, "TypeError: decoding
+            Unicode is not supported.")
+
+          encoding: the encoding to pass to the to_unicode attribute.
+            Defaults to None.
+
+        """
+        if isinstance(s, unicode):
+            return unicode(s)
+
+        return self.to_unicode(s, encoding)
+
+    def read(self, path, encoding=None):
+        """
+        Read the template at the given path, and return it as a unicode string.
+
+        """
+        b = common.read(path)
+
+        if encoding is None:
+            encoding = self.file_encoding
+
+        return self.unicode(b, encoding)
+
+    def load_file(self, file_name):
+        """
+        Find and return the template with the given file name.
+
+        Arguments:
+
+          file_name: the file name of the template.
+
+        """
+        locator = self._make_locator()
+
+        path = locator.find_file(file_name, self.search_dirs)
+
+        return self.read(path)
+
+    def load_name(self, name):
+        """
+        Find and return the template with the given template name.
+
+        Arguments:
+
+          name: the name of the template.
+
+        """
+        locator = self._make_locator()
+
+        path = locator.find_name(name, self.search_dirs)
+
+        return self.read(path)
+
+    # TODO: unit-test this method.
+    def load_object(self, obj):
+        """
+        Find and return the template associated to the given object.
+
+        Arguments:
+
+          obj: an instance of a user-defined class.
+
+          search_dirs: the list of directories in which to search.
+
+        """
+        locator = self._make_locator()
+
+        path = locator.find_object(obj, self.search_dirs)
+
+        return self.read(path)

third_party/pystache/src/locator.py

+# coding: utf-8
+
+"""
+This module provides a Locator class for finding template files.
+
+"""
+
+import os
+import re
+import sys
+
+from pystache.common import TemplateNotFoundError
+from pystache import defaults
+
+
+class Locator(object):
+
+    def __init__(self, extension=None):
+        """
+        Construct a template locator.
+
+        Arguments:
+
+          extension: the template file extension, without the leading dot.
+            Pass False for no extension (e.g. to use extensionless template
+            files).  Defaults to the package default.
+
+        """
+        if extension is None:
+            extension = defaults.TEMPLATE_EXTENSION
+
+        self.template_extension = extension
+
+    def get_object_directory(self, obj):
+        """
+        Return the directory containing an object's defining class.
+
+        Returns None if there is no such directory, for example if the
+        class was defined in an interactive Python session, or in a
+        doctest that appears in a text file (rather than a Python file).
+
+        """
+        if not hasattr(obj, '__module__'):
+            return None
+
+        module = sys.modules[obj.__module__]
+
+        if not hasattr(module, '__file__'):
+            # TODO: add a unit test for this case.
+            return None
+
+        path = module.__file__
+
+        return os.path.dirname(path)
+
+    def make_template_name(self, obj):
+        """
+        Return the canonical template name for an object instance.
+
+        This method converts Python-style class names (PEP 8's recommended
+        CamelCase, aka CapWords) to lower_case_with_underscords.  Here
+        is an example with code:
+
+        >>> class HelloWorld(object):
+        ...     pass
+        >>> hi = HelloWorld()
+        >>>
+        >>> locator = Locator()
+        >>> locator.make_template_name(hi)
+        'hello_world'
+
+        """
+        template_name = obj.__class__.__name__
+
+        def repl(match):
+            return '_' + match.group(0).lower()
+
+        return re.sub('[A-Z]', repl, template_name)[1:]
+
+    def make_file_name(self, template_name, template_extension=None):
+        """
+        Generate and return the file name for the given template name.
+
+        Arguments:
+
+          template_extension: defaults to the instance's extension.
+
+        """
+        file_name = template_name
+
+        if template_extension is None:
+            template_extension = self.template_extension
+
+        if template_extension is not False:
+            file_name += os.path.extsep + template_extension
+
+        return file_name
+
+    def _find_path(self, search_dirs, file_name):
+        """
+        Search for the given file, and return the path.
+
+        Returns None if the file is not found.
+
+        """
+        for dir_path in search_dirs:
+            file_path = os.path.join(dir_path, file_name)
+            if os.path.exists(file_path):
+                return file_path
+
+        return None
+
+    def _find_path_required(self, search_dirs, file_name):
+        """
+        Return the path to a template with the given file name.
+
+        """
+        path = self._find_path(search_dirs, file_name)
+
+        if path is None:
+            raise TemplateNotFoundError('File %s not found in dirs: %s' %
+                                        (repr(file_name), repr(search_dirs)))
+
+        return path
+
+    def find_file(self, file_name, search_dirs):
+        """
+        Return the path to a template with the given file name.
+
+        Arguments:
+
+          file_name: the file name of the template.
+
+          search_dirs: the list of directories in which to search.
+
+        """
+        return self._find_path_required(search_dirs, file_name)
+
+    def find_name(self, template_name, search_dirs):
+        """
+        Return the path to a template with the given name.
+
+        Arguments:
+
+          template_name: the name of the template.
+
+          search_dirs: the list of directories in which to search.
+
+        """
+        file_name = self.make_file_name(template_name)
+
+        return self._find_path_required(search_dirs, file_name)
+
+    def find_object(self, obj, search_dirs, file_name=None):
+        """
+        Return the path to a template associated with the given object.
+
+        """
+        if file_name is None:
+            # TODO: should we define a make_file_name() method?
+            template_name = self.make_template_name(obj)
+            file_name = self.make_file_name(template_name)
+
+        dir_path = self.get_object_directory(obj)
+
+        if dir_path is not None:
+            search_dirs = [dir_path] + search_dirs
+
+        path = self._find_path_required(search_dirs, file_name)
+
+        return path

third_party/pystache/src/parsed.py

+# coding: utf-8
+
+"""
+Exposes a class that represents a parsed (or compiled) template.
+
+"""
+
+
+class ParsedTemplate(object):
+
+    """
+    Represents a parsed or compiled template.
+
+    An instance wraps a list of unicode strings and node objects.  A node
+    object must have a `render(engine, stack)` method that accepts a
+    RenderEngine instance and a ContextStack instance and returns a unicode
+    string.
+
+    """
+
+    def __init__(self):
+        self._parse_tree = []
+
+    def __repr__(self):
+        return repr(self._parse_tree)
+
+    def add(self, node):
+        """
+        Arguments:
+
+          node: a unicode string or node object instance.  See the class
+            docstring for information.
+
+        """
+        self._parse_tree.append(node)
+
+    def render(self, engine, context):
+        """
+        Returns: a string of type unicode.
+
+        """
+        # We avoid use of the ternary operator for Python 2.4 support.
+        def get_unicode(node):
+            if type(node) is unicode:
+                return node
+            return node.render(engine, context)
+        parts = map(get_unicode, self._parse_tree)
+        s = ''.join(parts)
+
+        return unicode(s)

third_party/pystache/src/renderengine.py

+# coding: utf-8
+
+"""
+Defines a class responsible for rendering logic.
+
+"""
+
+import re
+
+from pystache.common import is_string
+from pystache.parser import parse
+
+
+def context_get(stack, name):
+    """
+    Find and return a name from a ContextStack instance.
+
+    """
+    return stack.get(name)
+
+
+class RenderEngine(object):
+
+    """
+    Provides a render() method.
+
+    This class is meant only for internal use.
+
+    As a rule, the code in this class operates on unicode strings where
+    possible rather than, say, strings of type str or markupsafe.Markup.
+    This means that strings obtained from "external" sources like partials
+    and variable tag values are immediately converted to unicode (or
+    escaped and converted to unicode) before being operated on further.
+    This makes maintaining, reasoning about, and testing the correctness
+    of the code much simpler.  In particular, it keeps the implementation
+    of this class independent of the API details of one (or possibly more)
+    unicode subclasses (e.g. markupsafe.Markup).
+
+    """
+
+    # TODO: it would probably be better for the constructor to accept
+    #   and set as an attribute a single RenderResolver instance
+    #   that encapsulates the customizable aspects of converting
+    #   strings and resolving partials and names from context.
+    def __init__(self, literal=None, escape=None, resolve_context=None,
+                 resolve_partial=None, to_str=None):
+        """
+        Arguments:
+
+          literal: the function used to convert unescaped variable tag
+            values to unicode, e.g. the value corresponding to a tag
+            "{{{name}}}".  The function should accept a string of type
+            str or unicode (or a subclass) and return a string of type
+            unicode (but not a proper subclass of unicode).
+                This class will only pass basestring instances to this
+            function.  For example, it will call str() on integer variable
+            values prior to passing them to this function.
+
+          escape: the function used to escape and convert variable tag
+            values to unicode, e.g. the value corresponding to a tag
+            "{{name}}".  The function should obey the same properties
+            described above for the "literal" function argument.
+                This function should take care to convert any str
+            arguments to unicode just as the literal function should, as
+            this class will not pass tag values to literal prior to passing
+            them to this function.  This allows for more flexibility,
+            for example using a custom escape function that handles
+            incoming strings of type markupsafe.Markup differently
+            from plain unicode strings.
+
+          resolve_context: the function to call to resolve a name against
+            a context stack.  The function should accept two positional
+            arguments: a ContextStack instance and a name to resolve.
+
+          resolve_partial: the function to call when loading a partial.
+            The function should accept a template name string and return a
+            template string of type unicode (not a subclass).
+
+          to_str: a function that accepts an object and returns a string (e.g.
+            the built-in function str).  This function is used for string
+            coercion whenever a string is required (e.g. for converting None
+            or 0 to a string).
+
+        """
+        self.escape = escape
+        self.literal = literal
+        self.resolve_context = resolve_context
+        self.resolve_partial = resolve_partial
+        self.to_str = to_str
+
+    # TODO: Rename context to stack throughout this module.
+
+    # From the spec:
+    #
+    #   When used as the data value for an Interpolation tag, the lambda
+    #   MUST be treatable as an arity 0 function, and invoked as such.
+    #   The returned value MUST be rendered against the default delimiters,
+    #   then interpolated in place of the lambda.
+    #
+    def fetch_string(self, context, name):
+        """
+        Get a value from the given context as a basestring instance.
+
+        """
+        val = self.resolve_context(context, name)
+
+        if callable(val):
+            # Return because _render_value() is already a string.
+            return self._render_value(val(), context)
+
+        if not is_string(val):
+            return self.to_str(val)
+
+        return val
+
+    def fetch_section_data(self, context, name):
+        """
+        Fetch the value of a section as a list.
+
+        """
+        data = self.resolve_context(context, name)
+
+        # From the spec:
+        #
+        #   If the data is not of a list type, it is coerced into a list
+        #   as follows: if the data is truthy (e.g. `!!data == true`),
+        #   use a single-element list containing the data, otherwise use
+        #   an empty list.
+        #
+        if not data:
+            data = []
+        else:
+            # The least brittle way to determine whether something
+            # supports iteration is by trying to call iter() on it:
+            #
+            #   http://docs.python.org/library/functions.html#iter
+            #
+            # It is not sufficient, for example, to check whether the item
+            # implements __iter__ () (the iteration protocol).  There is
+            # also __getitem__() (the sequence protocol).  In Python 2,
+            # strings do not implement __iter__(), but in Python 3 they do.
+            try:
+                iter(data)
+            except TypeError:
+                # Then the value does not support iteration.
+                data = [data]
+            else:
+                if is_string(data) or isinstance(data, dict):
+                    # Do not treat strings and dicts (which are iterable) as lists.
+                    data = [data]
+                # Otherwise, treat the value as a list.
+
+        return data
+
+    def _render_value(self, val, context, delimiters=None):
+        """
+        Render an arbitrary value.
+
+        """
+        if not is_string(val):
+            # In case the template is an integer, for example.
+            val = self.to_str(val)
+        if type(val) is not unicode:
+            val = self.literal(val)
+        return self.render(val, context, delimiters)
+
+    def render(self, template, context_stack, delimiters=None):
+        """
+        Render a unicode template string, and return as unicode.
+
+        Arguments:
+
+          template: a template string of type unicode (but not a proper
+            subclass of unicode).
+
+          context_stack: a ContextStack instance.
+
+        """
+        parsed_template = parse(template, delimiters)
+
+        return parsed_template.render(self, context_stack)

third_party/pystache/src/specloader.py

+# coding: utf-8
+
+"""
+This module supports customized (aka special or specified) template loading.
+
+"""
+
+import os.path
+
+from pystache.loader import Loader
+
+
+# TODO: add test cases for this class.
+class SpecLoader(object):
+
+    """
+    Supports loading custom-specified templates (from TemplateSpec instances).
+
+    """
+
+    def __init__(self, loader=None):
+        if loader is None:
+            loader = Loader()
+
+        self.loader = loader
+
+    def _find_relative(self, spec):
+        """
+        Return the path to the template as a relative (dir, file_name) pair.
+
+        The directory returned is relative to the directory containing the
+        class definition of the given object.  The method returns None for
+        this directory if the directory is unknown without first searching
+        the search directories.
+
+        """
+        if spec.template_rel_path is not None:
+            return os.path.split(spec.template_rel_path)
+        # Otherwise, determine the file name separately.
+
+        locator = self.loader._make_locator()
+
+        # We do not use the ternary operator for Python 2.4 support.
+        if spec.template_name is not None:
+            template_name = spec.template_name
+        else:
+            template_name = locator.make_template_name(spec)
+
+        file_name = locator.make_file_name(template_name, spec.template_extension)
+
+        return (spec.template_rel_directory, file_name)
+
+    def _find(self, spec):
+        """
+        Find and return the path to the template associated to the instance.
+
+        """
+        if spec.template_path is not None:
+            return spec.template_path
+
+        dir_path, file_name = self._find_relative(spec)
+
+        locator = self.loader._make_locator()
+
+        if dir_path is None:
+            # Then we need to search for the path.
+            path = locator.find_object(spec, self.loader.search_dirs, file_name=file_name)
+        else:
+            obj_dir = locator.get_object_directory(spec)
+            path = os.path.join(obj_dir, dir_path, file_name)
+
+        return path
+
+    def load(self, spec):
+        """
+        Find and return the template associated to a TemplateSpec instance.
+
+        Returns the template as a unicode string.
+
+        Arguments:
+
+          spec: a TemplateSpec instance.
+
+        """
+        if spec.template is not None:
+            return self.loader.unicode(spec.template, spec.template_encoding)
+
+        path = self._find(spec)
+
+        return self.loader.read(path, spec.template_encoding)

third_party/pystache/src/template_spec.py

+# coding: utf-8
+
+"""
+Provides a class to customize template information on a per-view basis.
+
+To customize template properties for a particular view, create that view
+from a class that subclasses TemplateSpec.  The "spec" in TemplateSpec
+stands for "special" or "specified" template information.
+
+"""
+
+class TemplateSpec(object):
+
+    """
+    A mixin or interface for specifying custom template information.
+
+    The "spec" in TemplateSpec can be taken to mean that the template
+    information is either "specified" or "special."
+
+    A view should subclass this class only if customized template loading
+    is needed.  The following attributes allow one to customize/override
+    template information on a per view basis.  A None value means to use
+    default behavior for that value and perform no customization.  All
+    attributes are initialized to None.
+
+    Attributes:
+
+      template: the template as a string.
+
+      template_encoding: the encoding used by the template.
+
+      template_extension: the template file extension.  Defaults to "mustache".
+        Pass False for no extension (i.e. extensionless template files).
+
+      template_name: the name of the template.
+
+      template_path: absolute path to the template.
+
+      template_rel_directory: the directory containing the template file,
+        relative to the directory containing the module defining the class.
+
+      template_rel_path: the path to the template file, relative to the
+        directory containing the module defining the class.
+
+    """
+
+    template = None
+    template_encoding = None
+    template_extension = None
+    template_name = None
+    template_path = None
+    template_rel_directory = None
+    template_rel_path = None