Make pdop and sdop instances native sympy objects

Author: eric-wieser

galgebra/_full_set.py

@@ -0,0 +1,50 @@
+class FullSet(set):
+    """ A set that contains everything. This is used to trick sympy. """
+    def __contains__(self, x):
+        return True
+
+    def __iter__(self):
+        raise RuntimeError("Set is infinite")
+
+    def __len__(self):
+        raise RuntimeError("Set is infinite")
+
+    def __and__(self, other):
+        if isinstance(other, set):
+            return other
+        return NotImplemented
+    __rand__ = __and__
+
+    def __or__(self, other):
+        if isinstance(other, set):
+            return self
+        return NotImplemented
+    __ror__ = __or__
+
+    def __gt__(self, other):
+        if isinstance(other, set):
+            return True
+        elif isinstance(other, FullSet):
+            return False
+        return NotImplemented
+
+    def __lt__(self, other):
+        if isinstance(other, FullSet):
+            return False
+        return NotImplemented
+
+    def __ge__(self, other):
+        return not (self < other)
+
+    def __le__(self, other):
+        return not (self > other)
+
+    def __eq__(self, other):
+        if isinstance(other, set):
+            return False
+        elif isinstance(other, FullSet):
+            return True
+        return NotImplemented
+
+    def __bool__(self):
+        return True