Make backend implementations not depends on container class.

- Parser class of backends just process dict or OrderedDict objects now.
- Conversion from dict or OrderedDict to m9dicts's dict object to
  support recursive merge operations are done in .api.*load explicitly.
- .backend.base.to_container_fn was deprecated and replaced with
  .backend.base.Parser._container_fn which selects dict class used for
  loaded results from dict and OrderedDict based on Parser.ordered()
  (Parser._ordered) and ac_ordered argument passed to Parser.*load*.

anyconfig/api.py

@@ -244,7 +244,7 @@ def single_load(path_or_stream, ac_parser=None, ac_template=False,
             LOGGER.warning("Failed to compile %s, fallback to no template "
                            "mode, exc=%r", path_or_stream, exc)
 
-    cnf = psr.load(path_or_stream, **options)
+    cnf = to_container(psr.load(path_or_stream, **options), **options)
     return _maybe_validated(cnf, schema, **options)
 
 
@@ -321,6 +321,8 @@ def multi_load(paths, ac_parser=None, ac_template=False, ac_context=None,
         if cups:
             cnf.update(cups)
 
+    # Disabled for a while: convert to normal dicts, dict or OrderedDict.
+    # cnf = anyconfig.mdicts.convert_to(cnf, **options)
     return _maybe_validated(cnf, schema, **options)
 
 

anyconfig/backend/base.py

@@ -3,7 +3,7 @@
 # License: MIT
 #
 # pylint: disable=unused-argument
-"""Abstract implementation of backend modules.
+r"""Abstract implementation of backend modules:
 
 Backend module must implement a parser class inherits :class:`Parser` or its
 children classes of this module and override all or some of the methods as
@@ -16,12 +16,18 @@
   - :meth:`dump_to_stream`: Dump config to a file or file-like object
   - :meth:`dump_to_path`: Dump config to a file of given path
 
-History:
+Changelog:
+
+.. versionchanged:: 0.8.3
+
+   - Add `_ordered` membmer and a class method :meth:` ordered to the class
+     :class:`Parser`.
 
 .. versionchanged:: 0.2
-   The methods :meth:`load_impl`, :meth:`dump_impl` are deprecated and replaced
-   with :meth:`load_from_stream` and :meth:`load_from_path`,
-   :meth:`dump_to_string` and :meth:`dump_to_path` respectively.
+
+   - The methods :meth:`load_impl`, :meth:`dump_impl` are deprecated and
+     replaced with :meth:`load_from_stream` and :meth:`load_from_path`,
+     :meth:`dump_to_string` and :meth:`dump_to_path` respectively.
 """
 from __future__ import absolute_import
 
@@ -81,16 +87,6 @@ def wrapper(*args, **kwargs):
     return wrapper
 
 
-def to_container_fn(**options):
-    """
-    :param options:
-        Keyword options will be passed to :func:`to_container` in
-        :mod:`anyconfig.mdicts` to decide which merge-able dict to
-        wrap configurations.
-    """
-    return functools.partial(anyconfig.mdicts.to_container, **options)
-
-
 class Parser(object):
     """
     Abstract parser to provide basic implementation of some methods, interfaces
@@ -102,6 +98,7 @@ class Parser(object):
     _load_opts = []
     _dump_opts = []
     _open_flags = ('r', 'w')
+    _ordered = False
 
     @classmethod
     def type(cls):
@@ -124,6 +121,13 @@ def extensions(cls):
         """
         return cls._extensions
 
+    @classmethod
+    def ordered(cls):
+        """
+        :return: True if parser can keep the order of keys else False.
+        """
+        return cls._ordered
+
     @classmethod
     def ropen(cls, filepath, **kwargs):
         """
@@ -144,6 +148,16 @@ def _load_options(self, **kwargs):
         """
         return mk_opt_args(self._load_opts, kwargs)
 
+    def _container_fn(self, **options):
+        """
+        :param options: Keyword options may contain 'ac_ordered'.
+        :return: Factory (class or function) to make an container.
+        """
+        if self.ordered() and options.get("ac_ordered", False):
+            return anyconfig.compat.OrderedDict
+        else:
+            return dict
+
     def load_from_string(self, content, to_container, **kwargs):
         """
         Load config from given string `content`.
@@ -192,7 +206,7 @@ def loads(self, content, **options):
 
         :return: dict or dict-like object holding configurations
         """
-        to_container = to_container_fn(**options)
+        to_container = self._container_fn(**options)
         if not content or content is None:
             return to_container()
 
@@ -216,7 +230,7 @@ def load(self, path_or_stream, ignore_missing=False, **options):
 
         :return: dict or dict-like object holding configurations
         """
-        to_container = to_container_fn(**options)
+        to_container = self._container_fn(**options)
         options = self._load_options(**options)
 
         if isinstance(path_or_stream, anyconfig.compat.STR_TYPES):

anyconfig/backend/bson.py

@@ -49,6 +49,7 @@ class Parser(anyconfig.backend.base.FromStringLoader,
     _load_opts = [] if bson.has_c() else ["tz_aware", "uuid_subtype"]
     _dump_opts = ["check_keys", "uuid_subtype"]
     _open_flags = ('rb', 'wb')
+    _ordered = not bson.has_c()
 
     dump_to_string = anyconfig.backend.base.to_method(bson.BSON.encode)
 

anyconfig/backend/configobj.py

@@ -81,6 +81,7 @@ class Parser(anyconfig.backend.base.FromStreamLoader,
     _load_opts = _LOAD_OPTS  # options on dump will be just ignored.
     _dump_opts = _LOAD_OPTS  # Likewise.
     _open_flags = ('rb', 'wb')
+    _ordered = True
 
     load_from_path = load_from_stream = anyconfig.backend.base.to_method(load)
 

anyconfig/backend/json.py

@@ -58,6 +58,7 @@ class Parser(anyconfig.backend.base.FromStreamLoader,
     _extensions = ["json", "jsn", "js"]
     _load_opts = _LOAD_OPTS
     _dump_opts = _DUMP_OPTS
+    _ordered = True
 
     dump_to_string = anyconfig.backend.base.to_method(json.dumps)
     dump_to_stream = anyconfig.backend.base.to_method(json.dump)
@@ -73,7 +74,7 @@ def _load(self, load_fn, content_or_strm, to_container, **opts):
         :return: Dict-like object holding configuration
         """
         if "object_pairs_hook" in self._load_opts:
-            opts["object_pairs_hook"] = anyconfig.compat.OrderedDict
+            opts["object_pairs_hook"] = self._container_fn(**opts)
             return to_container(load_fn(content_or_strm, **opts))
         else:
             return load_fn(content_or_strm, object_hook=to_container, **opts)

anyconfig/backend/msgpack.py

@@ -42,6 +42,7 @@ class Parser(anyconfig.backend.base.FromStreamLoader,
     _dump_opts = ["default", "encoding", "unicode_errors", "use_single_float",
                   "autoreset", "use_bin_type"]
     _open_flags = ('rb', 'wb')
+    _ordered = True
 
     dump_to_string = to_method(msgpack.packb)
     dump_to_stream = to_method(msgpack.pack)

anyconfig/backend/properties.py

@@ -198,6 +198,7 @@ class Parser(anyconfig.backend.base.FromStreamLoader,
     """
     _type = "properties"
     _extensions = ["properties"]
+    _ordered = True
 
     def load_from_stream(self, stream, to_container, **kwargs):
         """

anyconfig/backend/shellvars.py

@@ -107,6 +107,7 @@ class Parser(anyconfig.backend.base.FromStreamLoader,
     Parser for Shell variable definition files.
     """
     _type = "shellvars"
+    _ordered = True
 
     def load_from_stream(self, stream, to_container, **kwargs):
         """

anyconfig/backend/toml.py

@@ -34,6 +34,7 @@ class Parser(anyconfig.backend.base.FromStreamLoader,
     """
     _type = "toml"
     _extensions = ["toml"]
+    _ordered = True
 
     dump_to_string = to_method(toml.dumps)
     dump_to_stream = to_method(toml.dump)

anyconfig/backend/xml.py

@@ -443,6 +443,7 @@ class Parser(anyconfig.backend.base.ToStreamDumper):
     _extensions = ["xml"]
     _open_flags = ('rb', 'wb')
     _load_opts = _dump_opts = ["tags", "merge_attrs", "ac_parse_value"]
+    _ordered = True
 
     def load_from_string(self, content, to_container, **opts):
         """

tests/backend/base.py

@@ -13,7 +13,7 @@
 import tests.common
 
 
-MZERO = TT.to_container_fn()()
+MZERO = TT.Parser()._container_fn()()
 
 
 class Test00(unittest.TestCase):

tests/backend/cbor.py

@@ -19,7 +19,6 @@ class Test10(tests.backend.ini.Test10):
         cnf = dict(a=0, b="bbb", c=5, sect0=dict(d=["x", "y", "z"]))
         cnf_s = TT.cbor.dumps(cnf)
         load_options = dump_options = dict(sort_keys=False)
-        is_order_kept = False
 
         def setUp(self):
             self.psr = TT.Parser()

tests/backend/ini.py

@@ -12,7 +12,6 @@
 import tests.common
 
 from anyconfig.compat import OrderedDict as ODict
-from anyconfig.mdicts import UpdateWithReplaceDict
 from tests.common import dicts_equal
 
 
@@ -39,7 +38,7 @@ class Test10(unittest.TestCase):
     cnf_s = CNF_0_S
     load_options = dict(allow_no_value=False, defaults=None)
     dump_options = dict()
-    is_order_kept = True
+    is_order_kept = TT.Parser.ordered()
 
     def setUp(self):
         self.psr = TT.Parser()
@@ -48,7 +47,8 @@ def _assert_dicts_equal(self, cnf, ordered=False, instance_check=False):
         self.assertTrue(dicts_equal(cnf, self.cnf, ordered=ordered),
                         "\n %r\nvs.\n %r" % (cnf, self.cnf))
         if instance_check:
-            self.assertTrue(isinstance(cnf, UpdateWithReplaceDict))
+            cls = ODict if self.is_order_kept and ordered else dict
+            self.assertTrue(isinstance(cnf, cls))
 
     def test_10_loads(self):
         cnf = self.psr.loads(self.cnf_s)
@@ -136,10 +136,12 @@ def setUp(self):
     def tearDown(self):
         tests.common.cleanup_workdir(self.workdir)
 
-    def _assert_dicts_equal(self, cnf):
+    def _assert_dicts_equal(self, cnf, ordered=False, instance_check=False):
         self.assertTrue(dicts_equal(cnf, self.cnf),
                         "\n %r\nvs.\n %r" % (cnf, self.cnf))
-        self.assertTrue(isinstance(cnf, UpdateWithReplaceDict))
+        if instance_check:
+            cls = ODict if self.is_order_kept and ordered else dict
+            self.assertTrue(isinstance(cnf, cls))
 
     def test_10_load(self):
         cnf = self.psr.load(self.cpath)