1 files changed, 97 insertions, 0 deletions
diff --git a/vicn/core/scheduling_algebra.py b/vicn/core/scheduling_algebra.py
new file mode 100644
index 00000000..207856c0
--- /dev/null
+++ b/vicn/core/scheduling_algebra.py
@@ -0,0 +1,97 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+#
+# Copyright (c) 2017 Cisco and/or its affiliates.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at:
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+def SchedulingAlgebra(cls, concurrent_mixin=object, composition_mixin=object, 
+        sequential_mixin=object): # allow_none = True
+
+    class BaseElement(cls):
+        def __default__(cls, *elements):
+            elts = [e for e in elements 
+                if e is not None and not isinstance(e, Empty)]
+            if len(elts) == 0:
+                # The first is always Empty
+                assert len(elements) != 0
+                return elements[0]
+            elif len(elts) == 1:
+                return elts[0] 
+            return cls(*elts)
+
+        def __concurrent__(*elements):
+            return BaseElement.__default__(Concurrent, *elements)
+
+        def __composition__(*elements):
+            return BaseElement.__default__(Composition, *elements)
+
+        def __sequential__(*elements):
+            return BaseElement.__default__(Sequential, *elements)
+
+         # Operator: |
+        __or__ = __concurrent__
+
+        # Operator: >
+        __gt__ = __sequential__
+
+        # Operator: @
+        __matmul__ = __composition__
+
+    class Element(BaseElement):
+        def __iter__(self):
+            yield self
+
+    class Operator(BaseElement):
+        def __init__(self, *elements):
+            super().__init__()
+            self._elements = list(elements)
+
+        def __iter__(self):
+            yield self
+            for element in self._elements:
+                for x in element:
+                    yield x
+
+    class Concurrent(Operator, concurrent_mixin):
+        # Algebraic rule : ((A // B) // C) ~ (A // B // C)
+        def __concurrent__(self, other):
+            self._elements.append(other)
+            return self
+
+        def __repr__(self):
+            return '<Concurrent {}>'.format(self._elements)
+
+    class Composition(Operator, composition_mixin):
+        def __repr__(self):
+            return '<Composition {}>'.format(self._elements)
+
+    class Sequential(Operator, sequential_mixin):
+        def __repr__(self):
+            return '<Sequential {}>'.format(self._elements)
+
+    class Empty(Element):
+        def __concurrent__(self, other):
+            return other
+
+        def __composition__(self, other):
+            return other
+
+        def __sequential__(self, other):
+            return other
+
+        def __repr__(self):
+            return '<Empty>'
+
+    return Element, Empty