enhancement: make ruamel.yaml based backend works w/o PyYAML

Make ruamel.yaml based backend works w/o PyYAML by:

- Introduce anyconfig.backend.yaml.common to move common parts
  from anyconfig.backend.yamlpyyaml
- Remove dependency to anyconfig.backend.yaml.pyyaml from
  anyconfig.backend.yaml.ruamel_yaml and simplify it

This enhanement also might close the issue #99.

anyconfig/backend/yaml/common.py

@@ -0,0 +1,36 @@
+#
+# Copyright (C) 2011 - 2018 Satoru SATOH <ssato @ redhat.com>
+# Copyright (C) 2019 Satoru SATOH <satoru.satoh@gmail.com>
+# License: MIT
+#
+r"""Common parts for YAML backends:
+"""
+from __future__ import absolute_import
+import anyconfig.backend.base
+
+
+def filter_from_options(key, options):
+    """
+    :param key: Key str in options
+    :param options: Mapping object
+    :return:
+        New mapping object from `options` in which the item with `key` filtered
+
+    >>> filter_from_options('a', dict(a=1, b=2))
+    {'b': 2}
+    """
+    return anyconfig.utils.filter_options([k for k in options.keys()
+                                           if k != key], options)
+
+
+class Parser(anyconfig.backend.base.StreamParser):
+    """
+    Parser for YAML files.
+    """
+    _type = "yaml"
+    _extensions = ["yaml", "yml"]
+    _ordered = True
+    _allow_primitives = True
+    _dict_opts = ["ac_dict"]
+
+# vim:sw=4:ts=4:et:

anyconfig/backend/yaml/pyyaml.py

@@ -49,22 +49,10 @@
 import anyconfig.compat
 import anyconfig.utils
 
+from . import common
 
-_MAPPING_TAG = yaml.resolver.BaseResolver.DEFAULT_MAPPING_TAG
-
-
-def filter_from_options(key, options):
-    """
-    :param key: Key str in options
-    :param options: Mapping object
-    :return:
-        New mapping object from `options` in which the item with `key` filtered
 
-    >>> filter_from_options('a', dict(a=1, b=2))
-    {'b': 2}
-    """
-    return anyconfig.utils.filter_options([k for k in options.keys()
-                                           if k != key], options)
+_MAPPING_TAG = yaml.resolver.BaseResolver.DEFAULT_MAPPING_TAG
 
 
 def _customized_loader(container, loader=Loader, mapping_tag=_MAPPING_TAG):
@@ -151,7 +139,7 @@ def yml_fnc(fname, *args, **options):
     """
     key = "ac_safe"
     fnc = getattr(yaml, r"safe_" + fname if options.get(key) else fname)
-    return fnc(*args, **filter_from_options(key, options))
+    return fnc(*args, **common.filter_from_options(key, options))
 
 
 def yml_load(stream, container, yml_fnc=yml_fnc, **options):
@@ -171,7 +159,8 @@ def yml_load(stream, container, yml_fnc=yml_fnc, **options):
 
         options["Loader"] = _customized_loader(container)
 
-    ret = yml_fnc("load", stream, **filter_from_options("ac_dict", options))
+    ret = yml_fnc("load", stream,
+                  **common.filter_from_options("ac_dict", options))
     if ret is None:
         return container()
 
@@ -196,26 +185,21 @@ def yml_dump(data, stream, yml_fnc=yml_fnc, **options):
     if _is_dict:
         # Type information and the order of items are lost on dump currently.
         data = anyconfig.dicts.convert_to(data, ac_dict=dict)
-        options = filter_from_options("ac_dict", options)
+        options = common.filter_from_options("ac_dict", options)
 
     return yml_fnc("dump", data, stream, **options)
 
 
-class Parser(anyconfig.backend.base.StreamParser):
+class Parser(common.Parser):
     """
     Parser for YAML files.
     """
-    _type = "yaml"
     _cid = "pyyaml"
-    _extensions = ["yaml", "yml"]
     _load_opts = ["Loader", "ac_safe", "ac_dict"]
     _dump_opts = ["stream", "ac_safe", "Dumper", "default_style",
                   "default_flow_style", "canonical", "indent", "width",
                   "allow_unicode", "line_break", "encoding", "explicit_start",
                   "explicit_end", "version", "tags"]
-    _ordered = True
-    _allow_primitives = True
-    _dict_opts = ["ac_dict"]
 
     load_from_stream = anyconfig.backend.base.to_method(yml_load)
     dump_to_stream = anyconfig.backend.base.to_method(yml_dump)

anyconfig/backend/yaml/ruamel_yaml.py

@@ -39,9 +39,10 @@
 from __future__ import absolute_import
 
 import ruamel.yaml as ryaml
+import anyconfig.backend.base
 import anyconfig.utils
 
-from . import pyyaml
+from . import common
 
 
 try:
@@ -77,6 +78,8 @@ def yml_fnc(fname, *args, **options):
     :param args: [stream] for load or [cnf, stream] for dump
     :param options: keyword args may contain "ac_safe" to load/dump safely
     """
+    options = common.filter_from_options("ac_dict", options)
+
     if "ac_safe" in options:
         options["typ"] = "safe"  # Override it.
 
@@ -93,16 +96,27 @@ def yml_fnc(fname, *args, **options):
 def yml_load(stream, container, **options):
     """.. seealso:: :func:`anyconfig.backend.yaml.pyyaml.yml_load`
     """
-    return pyyaml.yml_load(stream, container, yml_fnc=yml_fnc, **options)
+    ret = yml_fnc("load", stream, **options)
+    if ret is None:
+        return container()
+
+    return ret
 
 
 def yml_dump(data, stream, **options):
     """.. seealso:: :func:`anyconfig.backend.yaml.pyyaml.yml_dump`
     """
-    return pyyaml.yml_dump(data, stream, yml_fnc=yml_fnc, **options)
+    # .. todo:: Needed?
+    # if anyconfig.utils.is_dict_like(data):
+    #     if options.get("ac_ordered"):
+    #         factory = collections.OrderedDict
+    #     else:
+    #         factory = dict
+    #     data = anyconfig.dicts.convert_to(data, ac_dict=factory)
+    return yml_fnc("dump", data, stream, **options)
 
 
-class Parser(pyyaml.Parser):
+class Parser(common.Parser):
     """Parser for YAML files.
     """
     _cid = "ruamel.yaml"