Implement none-behavior strategies

README.rst

@@ -139,6 +139,11 @@ kwargs
 
 - ``mergelists``: boolean try to merge lists of dict (default: ``True``)
 
+- ``none_behavior``: bit (one of the listed below):
+
+   -  ``hiyapyco.NONE_BEHAVIOR_DEFAULT``: attempt to merge the value with ``None`` and fail if this is not possible (default method)
+   -  ``hiyapyco.NONE_BEHAVIOR_OVERRIDE``: ``None`` always overrides any other value.
+
 -  ``interpolate``: boolean : perform interpolation after the merge
    (default: ``False``)
 

hiyapyco/__init__.py

@@ -65,6 +65,10 @@ class HiYaPyCoImplementationException(Exception):
 METHOD_MERGE = METHODS['METHOD_MERGE']
 METHOD_SUBSTITUTE = METHODS['METHOD_SUBSTITUTE']
 
+NONE_BEHAVIORS = {"NONE_BEHAVIOR_DEFAULT": 0x0001, "NONE_BEHAVIOR_OVERRIDE": 0x0002}
+NONE_BEHAVIOR_DEFAULT = NONE_BEHAVIORS["NONE_BEHAVIOR_DEFAULT"]
+NONE_BEHAVIOR_OVERRIDE = NONE_BEHAVIORS["NONE_BEHAVIOR_OVERRIDE"]
+
 
 class HiYaPyCo:
     """Main class"""
@@ -77,6 +81,7 @@ def __init__(self, *args, **kwargs):
             hiyapyco.METHOD_SIMPLE | hiyapyco.METHOD_MERGE | hiyapyco.METHOD_SUBSTITUTE
           * mergelists: boolean (default: True) try to merge lists
             (only makes sense if hiyapyco.METHOD_MERGE or hiyapyco.METHOD_SUBSTITUTE)
+          * none_behavior: one of hiyapyco.NONE_BEHAVIOR_DEFAULT | hiyapyco.NONE_BEHAVIOR_OVERRIDE
           * interpolate: boolean (default: False)
           * castinterpolated: boolean (default: False) try to cast values after interpolating
           * usedefaultyamlloader: boolean (default: False)
@@ -122,6 +127,19 @@ def __init__(self, *args, **kwargs):
             self.mergelists = kwargs['mergelists']
             del kwargs['mergelists']
 
+        self.none_behavior = None
+        if "none_behavior" in kwargs:
+            logger.debug("parse kwarg method: %s ..." % kwargs["none_behavior"])
+            if kwargs["none_behavior"] not in NONE_BEHAVIORS.values():
+                raise HiYaPyCoInvocationException(
+                    "undefined method used, must be one of: %s"
+                    % " ".join(NONE_BEHAVIORS.keys())
+                )
+            self.none_behavior = kwargs["none_behavior"]
+            del kwargs["none_behavior"]
+        if self.none_behavior is None:
+            self.none_behavior = NONE_BEHAVIOR_DEFAULT
+
         self.interpolate = False
         self.castinterpolated = False
         if 'interpolate' in kwargs:
@@ -333,8 +351,12 @@ def _simplemerge(self, a, b):
             a = copy.deepcopy(a)
             b = copy.deepcopy(b)
         logger.debug('simplemerge %s (%s) and %s (%s)' % (a, type(a), b, type(b),))
-        # FIXME: make None usage configurable
         if b is None:
+            # override -> None replaces object, no matter what.
+            if self.none_behavior == NONE_BEHAVIOR_OVERRIDE:
+                logger.debug('b is None + none_behavior in use => return None')
+                return None
+            # default behavior is to attempt merge or fail
             logger.debug('pass as b is None')
             pass
         elif isinstance(b, primitiveTypes):
@@ -374,6 +396,12 @@ def _substmerge(self, a, b):
         logger.debug('substmerge %s and %s' % (a, b,))
         # FIXME: make None usage configurable
         if b is None:
+            logger.debug('pass as b is None')
+            # override -> None replaces object, no matter what.
+            if self.none_behavior == NONE_BEHAVIOR_OVERRIDE:
+                logger.debug('b is None + none_behavior in use => return None')
+                return None
+            # default behavior is to attempt merge or fail
             logger.debug('pass as b is None')
             pass
 
@@ -429,6 +457,11 @@ def _deepmerge(self, a, b, context = None):
         logger.debug('deepmerge %s and %s' % (a, b,))
         # FIXME: make None usage configurable
         if b is None:
+            logger.debug('pass as b is None')
+            # override -> None replaces object, no matter what.
+            if self.none_behavior == NONE_BEHAVIOR_OVERRIDE:
+                return None
+            # default behavior is to attempt merge or fail
             logger.debug('pass as b is None')
             pass
         if a is None or isinstance(b, primitiveTypes):

test/base_none_behavior.yaml

@@ -0,0 +1,15 @@
+# vim: tabstop=4 expandtab shiftwidth=4 softtabstop=4 smartindent
+singel: null
+int: null
+array: null
+hash: null
+deeplist:
+    - d1: null
+    - d2:
+        d2k1: null
+        d2k2: x2
+deepmap:
+    l1k1:
+        l2k1: null
+        l2k2: abc
+    l1k2: null

test/test_merge.py

@@ -173,6 +173,65 @@
 except KeyError as e:
     assert '%s' % e == '\'nosuchelement\''
 
-print('passed test %s' % __file__)
+
+logger.info("test none behavior DEFAULT ...")
+for method in [hiyapyco.METHOD_MERGE, hiyapyco.METHOD_SUBSTITUTE]:
+    try:
+        conf = hiyapyco.load(
+            os.path.join(basepath, "base.yaml"),
+            os.path.join(basepath, "base_none_behavior.yaml"),
+            method=method,
+            failonmissingfiles=True,
+        )
+    except hiyapyco.HiYaPyCoImplementationException:
+        pass
+    else:
+        raise AssertionError("Default None behavior is expected to fail on this merge")
+
+logger.info("test none behavior OVERRIDE ...")
+for method in hiyapyco.METHODS.values():
+    conf = hiyapyco.load(
+        os.path.join(basepath, "base.yaml"),
+        os.path.join(basepath, "base_none_behavior.yaml"),
+        none_behavior=hiyapyco.NONE_BEHAVIOR_OVERRIDE,
+        method=hiyapyco.METHOD_MERGE,
+        failonmissingfiles=True,
+    )
+
+    t = conf["singel"]
+    logger.info("test single val ... %s" % t)
+    assert t is None
+
+    t = conf["int"]
+    logger.info("test int val ... %s" % t)
+    assert t is None
+
+    t = conf["array"]
+    logger.info("test list val ... %s" % t)
+    assert t is None
+
+    t = conf["hash"]
+    logger.info("test simple dict ... %s" % t)
+    assert t is None
+
+    t = conf["deeplist"]
+    logger.info("test deeplist ... %s" % t)
+    assert t == [
+        {"d1": None},
+        {"d2": {"d2k2": "x2", "d2k1": None}},
+        {
+            "d32": {"a": "A2", "b": "B2"},
+            "d31": {"a": "A", "c": "C", "b": "B"},
+        },
+    ]
+
+    t = conf["deepmap"]
+    logger.info("test deepmap ... %s" % t)
+    assert t == {
+        "l1k1": {"l2k1": None, "l2k2": "abc"},
+        "l1k2": None,
+    }
+
+print("passed test %s" % __file__)
 
 # vim: tabstop=4 expandtab shiftwidth=4 softtabstop=4 smartindent nu