Merge baf251f into 16aecea

spinn_utilities/ordered_default_dict.py

@@ -0,0 +1,48 @@
+try:
+    from collections.abc import OrderedDict, Callable
+except ImportError:
+    from collections import OrderedDict, Callable
+
+
+class DefaultOrderedDict(OrderedDict):
+    # Source: https://stackoverflow.com/questions/6190331
+    def __init__(self, default_factory=None, *a, **kw):
+        if (default_factory is not None and
+           not isinstance(default_factory, Callable)):
+            raise TypeError('first argument must be callable')
+        OrderedDict.__init__(self, *a, **kw)
+        self.default_factory = default_factory
+
+    def __getitem__(self, key):
+        try:
+            return OrderedDict.__getitem__(self, key)
+        except KeyError:
+            return self.__missing__(key)
+
+    def __missing__(self, key):
+        if self.default_factory is None:
+            raise KeyError(key)
+        self[key] = value = self.default_factory()
+        return value
+
+    def __reduce__(self):
+        if self.default_factory is None:
+            args = tuple()
+        else:
+            args = self.default_factory,
+        return type(self), args, None, None, self.items()
+
+    def copy(self):
+        return self.__copy__()
+
+    def __copy__(self):
+        return type(self)(self.default_factory, self)
+
+    def __deepcopy__(self, memo):
+        import copy
+        return type(self)(self.default_factory,
+                          copy.deepcopy(self.items()))
+
+    def __repr__(self):
+        return 'OrderedDefaultDict(%s, %s)' % (self.default_factory,
+                                               OrderedDict.__repr__(self))

unittests/test_ordered_default_dict.py

@@ -0,0 +1,30 @@
+import pytest
+from spinn_utilities.ordered_default_dict import DefaultOrderedDict
+from spinn_utilities.ordered_set import OrderedSet
+
+
+def test_standard_default():
+    o = DefaultOrderedDict()
+    assert o is not None
+    o["bar"] = 2
+    with pytest.raises(KeyError):  # @UndefinedVariable
+        o["FOO"]
+    assert o["bar"] == 2
+
+
+def test_list_default():
+    o = DefaultOrderedDict(list)
+    assert o is not None
+    o["bar"] = 2
+    assert isinstance(o["FOO"], list)
+    o["gamma"].append("beacon")
+    assert o["bar"] == 2
+
+
+def test_orderedset_default():
+    o = DefaultOrderedDict(OrderedSet)
+    assert o is not None
+    o["foo"].add(2)
+    o["foo"].add(1)
+    assert 2 in o["foo"]
+    assert 1 not in o["bar"]