support PyYAML 4.1.0

.travis.yml

@@ -11,12 +11,17 @@ python:
   - "pypy"
   - "pypy3.5"
 
+env:
+  - PYYAML_VERSION="3.12"
+  - PYYAML_VERSION="4.1"
+
 matrix:
   fast_finish: true
   allow_failures:
   - python: "nightly"
 
 install: 
+  - pip install pyyaml~=$PYYAML_VERSION
   - pip install --editable .
   - pip install pytest-cov coveralls
 

oyaml.py

@@ -15,11 +15,18 @@ def map_constructor(loader, node):
     loader.flatten_mapping(node)
     return OrderedDict(loader.construct_pairs(node))
 
-
-pyyaml.add_representer(dict, map_representer)
-pyyaml.add_representer(OrderedDict, map_representer)
-pyyaml.add_representer(dict, map_representer, Dumper=pyyaml.dumper.SafeDumper)
-pyyaml.add_representer(OrderedDict, map_representer, Dumper=pyyaml.dumper.SafeDumper)
+if pyyaml.safe_dump is pyyaml.dump:
+    # PyYAML >= 4
+    SafeDumper = pyyaml.dumper.Dumper
+    DangerDumper = pyyaml.dumper.DangerDumper
+else:
+    SafeDumper = pyyaml.dumper.SafeDumper
+    DangerDumper = pyyaml.dumper.Dumper
+
+pyyaml.add_representer(dict, map_representer, Dumper=SafeDumper)
+pyyaml.add_representer(OrderedDict, map_representer, Dumper=SafeDumper)
+pyyaml.add_representer(dict, map_representer, Dumper=DangerDumper)
+pyyaml.add_representer(OrderedDict, map_representer, Dumper=DangerDumper)
 
 
 if sys.version_info < (3, 7):

setup.py

@@ -2,7 +2,7 @@
 
 setup(
     name='oyaml',
-    version='0.4',
+    version='0.5',
     description='Ordered YAML: drop-in replacement for PyYAML which preserves dict ordering',
     long_description=open('README.rst').read(),
     author='Wim Glenn',

test_oyaml.py

@@ -58,18 +58,28 @@ def test_loads_to_std_dict():
     assert isinstance(loaded, dict)
 
 
-def test_subclass_dump():
+class MyOrderedDict(OrderedDict):
+    pass
 
-    class MyOrderedDict(OrderedDict):
-        pass
 
+@pytest.mark.skipif(yaml.pyyaml.__version__ >= '4', reason="requires PyYAML version < 4")
+def test_subclass_dump_pyyaml3():
     data = MyOrderedDict([('x', 1), ('y', 2)])
     assert '!!python/object/apply:test_oyaml.MyOrderedDict' in yaml.dump(data)
     with pytest.raises(yaml.pyyaml.representer.RepresenterError) as cm:
         yaml.safe_dump(data)
     assert str(cm.value) == "cannot represent an object: MyOrderedDict([('x', 1), ('y', 2)])"
 
 
+@pytest.mark.skipif(yaml.pyyaml.__version__ < '4', reason="requires PyYAML version >= 4")
+def test_subclass_dump_pyyaml4():
+    data = MyOrderedDict([('x', 1), ('y', 2)])
+    assert '!!python/object/apply:test_oyaml.MyOrderedDict' in yaml.danger_dump(data)
+    with pytest.raises(yaml.pyyaml.representer.RepresenterError) as cm:
+        yaml.dump(data)
+    assert str(cm.value) == "('cannot represent an object', MyOrderedDict([('x', 1), ('y', 2)]))"
+
+
 def test_anchors_and_references():
     text = '''
         defaults: