refactor(bdd): moved BitAnd impl into traits module

src/bdd/mod.rs

@@ -1,4 +1,5 @@
 mod iterators;
+mod traits;
 
 use std::collections::{BTreeMap, BTreeSet, HashMap, HashSet};
 use std::fmt::Debug;

src/bdd/traits/bit/and.rs

@@ -0,0 +1,32 @@
+use crate::bdd::{extend_bdd_variables, Bdd};
+use std::fmt::Debug;
+use std::ops::BitAnd;
+
+impl<TLiteral: Debug + Clone + Eq + Ord + 'static> BitAnd for Bdd<TLiteral> {
+    type Output = Bdd<TLiteral>;
+
+    fn bitand(self, rhs: Self) -> Self::Output {
+        if self.inputs == rhs.inputs {
+            Bdd {
+                inputs: self.inputs.clone(),
+                bdd: self.bdd.and(&rhs.bdd),
+            }
+        } else {
+            let mut common_inputs = self.inputs.clone();
+            for other in &rhs.inputs {
+                if !common_inputs.contains(other) {
+                    common_inputs.push(other.clone());
+                }
+            }
+            common_inputs.sort();
+
+            let self_lifted = extend_bdd_variables(&self, &common_inputs);
+            let rhs_lifted = extend_bdd_variables(&rhs, &common_inputs);
+
+            Bdd {
+                inputs: common_inputs,
+                bdd: self_lifted.bdd.and(&rhs_lifted.bdd),
+            }
+        }
+    }
+}

src/bdd/traits/bit/mod.rs

@@ -0,0 +1 @@
+mod and;

src/bdd/traits/mod.rs

@@ -0,0 +1 @@
+mod bit;