Python 2.5 compatibility

- Made sassutils.utils module for compatibility layer
- is_mapping(): alternative to collections.Mapping
- relpath(): alternative to os.path.relpath()

Author: dahlia

docs/sassutils.rst

@@ -6,4 +6,5 @@
 
       sassutils/builder
       sassutils/distutils
+      sassutils/utils
       sassutils/wsgi

docs/sassutils/utils.rst

@@ -0,0 +1,3 @@
+
+.. automodule:: sassutils.utils
+   :members:

sassutils/builder.py

@@ -4,12 +4,12 @@
 """
 from __future__ import with_statement
 
-import collections
 import os
 import os.path
 import re
 
 from sass import compile
+from .utils import is_mapping, relpath
 
 __all__ = 'SUFFIXES', 'SUFFIX_PATTERN', 'Manifest', 'build_directory'
 
@@ -49,8 +49,8 @@ def build_directory(sass_path, css_path, _root_sass=None, _root_css=None):
             css = compile(filename=sass_fullname, include_paths=[_root_sass])
             with open(css_fullname, 'w') as css_file:
                 css_file.write(css)
-            result[os.path.relpath(sass_fullname, _root_sass)] = \
-                os.path.relpath(css_fullname, _root_css)
+            result[relpath(sass_fullname, _root_sass)] = \
+                relpath(css_fullname, _root_css)
         elif os.path.isdir(sass_fullname):
             css_fullname = os.path.join(css_path, name)
             subresult = build_directory(sass_fullname, css_fullname,
@@ -75,7 +75,7 @@ class Manifest(object):
     def normalize_manifests(cls, manifests):
         if manifests is None:
             manifests = {}
-        elif isinstance(manifests, collections.Mapping):
+        elif is_mapping(manifests):
             manifests = dict(manifests)
         else:
             raise TypeError('manifests must be a mapping object, not ' +

sassutils/utils.py

@@ -0,0 +1,53 @@
+""":mod:`sassutils.utils` --- Utilities for internal use
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+"""
+import collections
+import functools
+import os.path
+
+
+__all__ = 'is_mapping', 'relpath'
+
+
+def is_mapping(value):
+    """The predicate method equivalent to::
+
+        isinstance(value, collections.Mapping)
+
+    This function works on Python 2.5 as well.
+
+    :param value: a value to test its type
+    :returns: ``True`` only if ``value`` is a mapping object
+    :rtype: :class:`bool`
+
+    """
+    return isinstance(value, collections.Mapping)
+
+
+if not hasattr(collections, 'Mapping'):
+    @functools.wraps(is_mapping)
+    def is_mapping(value):
+        return (callable(getattr(value, 'keys', None)) and
+                callable(getattr(value, 'values', None)) and
+                callable(getattr(value, 'items', None)) and
+                callable(getattr(value, '__getitem__', None)))
+
+
+def relpath(path, start=os.path.curdir):
+    """Equivalent to :func:`os.path.relpath()` except it's for
+    Python 2.5.
+
+    """
+    start_list = os.path.abspath(start).split(os.path.sep)
+    path_list = os.path.abspath(path).split(os.path.sep)
+    # Work out how much of the filepath is shared by start and path.
+    i = len(os.path.commonprefix([start_list, path_list]))
+    rel_list = [os.path.pardir] * (len(start_list)-i) + path_list[i:]
+    if not rel_list:
+        return os.path.curdir
+    return os.path.join(*rel_list)
+
+
+if hasattr(os.path, 'relpath'):
+    relpath = os.path.relpath

sassutils/wsgi.py

@@ -4,14 +4,14 @@
 """
 from __future__ import absolute_import, with_statement
 
-import collections
 import os
 import os.path
 
 import pkg_resources
 
 from sass import CompileError
 from .builder import Manifest
+from .utils import is_mapping
 
 __all__ = 'SassMiddleware',
 
@@ -41,7 +41,7 @@ def __init__(self, app, manifests, package_dir={},
                             'not ' + repr(app))
         self.app = app
         self.manifests = Manifest.normalize_manifests(manifests)
-        if not isinstance(package_dir, collections.Mapping):
+        if not is_mapping(package_dir):
             raise TypeError('package_dir must be a mapping object, not ' +
                             repr(package_dir))
         self.error_status = error_status
@@ -73,7 +73,7 @@ def __call__(self, environ, start_response):
                     result = manifest.build_one(package_dir, sass_filename)
                 except (IOError, OSError):
                     break
-                except CompileError as e:
+                except CompileError, e:
                     start_response(self.error_status,
                                    [('Content-Type', 'text/css')])
                     return [