pystache/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