perf: Switch to using ids for hashing and eq check.

closes: #135
BREAKING_CHANGE: Structually equal circuits will not necessarily be equal now.
co-authored-by: Gabriele Masina <[email protected]>

Author: mvcisback

aiger/aig.py

@@ -50,7 +50,7 @@ def children(self):
         pass
 
 
-@attr.frozen(cache_hash=True)
+@attr.frozen(auto_detect=True)
 class AndGate(Node):
     left: Node
     right: Node
@@ -59,15 +59,27 @@ class AndGate(Node):
     def children(self):
         return (self.left, self.right)
 
+    def __eq__(self, other) -> bool:
+        return id(self) == id(other)  # Allow for duplication.
 
-@attr.frozen
+    def __hash__(self) -> int:
+        return hash(id(self))
+
+
+@attr.frozen(auto_detect=True)
 class Inverter(Node):
     input: Node
 
     @property
     def children(self):
         return (self.input, )
 
+    def __eq__(self, other) -> bool:
+        return id(self) == id(other)  # Allow for duplication.
+
+    def __hash__(self) -> int:
+        return hash(id(self))
+
 
 @attr.frozen
 class Input(Node):
@@ -77,6 +89,12 @@ class Input(Node):
     def children(self):
         return ()
 
+    def __eq__(self, other) -> bool:
+        return isinstance(other, Input) and (self.name == other.name)
+
+    def __hash__(self) -> int:
+        return hash(("input", self.name))
+
 
 @attr.frozen
 class LatchIn(Node):
@@ -86,6 +104,12 @@ class LatchIn(Node):
     def children(self):
         return ()
 
+    def __eq__(self, other) -> bool:
+        return isinstance(other, LatchIn) and (self.name == other.name)
+
+    def __hash__(self) -> int:
+        return hash(("latch", self.name))
+
 
 @attr.frozen
 class ConstFalse(Node):

tests/test_expr.py

@@ -80,13 +80,3 @@ def test_with_output():
     x, y, z = map(atom, 'xyz')
     expr = ite(x, y, z).with_output('xyz')
     assert expr.with_output('xyz')
-
-
-def test_hash_stability():
-    x = atom('x')
-    y = atom('y')
-
-    expr1 = x | y
-    expr2 = (~~expr1).with_output(expr1.output)
-
-    assert hash(expr2) == hash(expr1)