Added pop() method to ConfigTree and added KeyError to ConfigMissingException

pyhocon/config_tree.py

@@ -204,6 +204,34 @@ def get_string(self, key, default=UndefinedKey):
             return string_value.lower()
         return string_value
 
+    def pop(self, key, default=UndefinedKey):
+        """Remove specified key and return the corresponding value.
+        If key is not found, default is returned if given, otherwise ConfigMissingException is raised
+
+        This method assumes the user wants to remove the last value in the chain so it parses via parse_key
+        and pops the last value out of the dict.
+
+        :param key: key to use (dot separated). E.g., a.b.c
+        :type key: basestring
+        :param default: default value if key not found
+        :type default: object
+        :param default: default value if key not found
+        :return: value in the tree located at key
+        """
+        value = self.get(key, default)
+        if value == default:
+            return default
+
+        lst = ConfigTree.parse_key(key)
+        parent = self.KEY_SEP.join(lst[0:-1])
+        child = lst[-1]
+
+        if parent:
+            self.get(parent).__delitem__(child)
+        else:
+            self.__delitem__(child)
+        return value
+
     def get_int(self, key, default=UndefinedKey):
         """Return int representation of value found at key
 

pyhocon/exceptions.py

@@ -5,7 +5,7 @@ def __init__(self, message, ex=None):
         self._exception = ex
 
 
-class ConfigMissingException(ConfigException):
+class ConfigMissingException(ConfigException, KeyError):
     pass
 
 

tests/test_config_tree.py

@@ -216,3 +216,58 @@ def test_contains_with_quoted_keys(self):
         assert 'a.c' not in config_tree
         assert 'a.b."c.d"' in config_tree
         assert 'a.b.c.d' not in config_tree
+
+    def test_configtree_pop(self):
+        config_tree = ConfigTree()
+        config_tree.put("string", "string")
+        assert config_tree.pop("string", "default") == "string"
+        assert config_tree.pop("string-new", "default") == "default"
+        assert config_tree == ConfigTree()
+
+        with pytest.raises(ConfigMissingException):
+            assert config_tree.pop("string-new")
+
+        config_tree.put("list", [1, 2, 3])
+        assert config_tree.pop("list", [4]) == [1, 2, 3]
+        assert config_tree.pop("list-new", [4]) == [4]
+        assert config_tree == ConfigTree()
+
+        config_tree.put("config", {'a': 5})
+        assert config_tree.pop("config", {'b': 1}) == {'a': 5}
+        assert config_tree.pop("config-new", {'b': 1}) == {'b': 1}
+        assert config_tree == ConfigTree()
+
+        config_tree = ConfigTree()
+        config_tree.put('a.b.c.one', 1)
+        config_tree.put('a.b.c.two', 2)
+        config_tree.put('"f.k".g.three', 3)
+
+        exp = OrderedDict()
+        exp['a'] = OrderedDict()
+        exp['a']['b'] = OrderedDict()
+        exp['a']['b']['c'] = OrderedDict()
+        exp['a']['b']['c']['one'] = 1
+        exp['a']['b']['c']['two'] = 2
+
+        exp['f.k'] = OrderedDict()
+        exp['f.k']['g'] = OrderedDict()
+        exp['f.k']['g']['three'] = 3
+
+        assert config_tree.pop('a.b.c').as_plain_ordered_dict() == exp['a']['b']['c']
+        assert config_tree.pop('a.b.c', None) is None
+
+        with pytest.raises(ConfigMissingException):
+            assert config_tree.pop('a.b.c')
+        with pytest.raises(ConfigMissingException):
+            assert config_tree['a']['b'].pop('c')
+
+        assert config_tree.pop('a').as_plain_ordered_dict() == OrderedDict(b=OrderedDict())
+        assert config_tree.pop('"f.k"').as_plain_ordered_dict() == OrderedDict(g=OrderedDict(three=3))
+        assert config_tree.as_plain_ordered_dict() == OrderedDict()
+
+    def test_keyerror_raised(self):
+        config_tree = ConfigTree()
+        config_tree.put("a", {'b': 5})
+
+        with pytest.raises(KeyError):
+            assert config_tree['c']