ditto

src/bdd.rs

@@ -13,13 +13,13 @@ use {
 };
 
 #[derive(Clone, Debug, Default, Eq, Hash, PartialEq)]
-pub struct BDD {
-    graph: Node,
+pub struct BDD<N: DecisionDiagramNode> {
+    graph: N,
     phantom: PhantomData<()>,
 }
 
-impl BDD {
-    pub fn new_from(graph: Node) -> BDD {
+impl BDD<Node> {
+    pub fn new_from(graph: Node) -> Self {
         let mut bdd = BDD {
             graph: graph.clone(),
             ..Default::default()
@@ -29,9 +29,8 @@ impl BDD {
     }
 }
 
-impl DecisionDiagram for BDD {
-    type Element = Node;
-    fn all_nodes(&self) -> HashSet<&Node> {
+impl<N: DecisionDiagram<N> + DecisionDiagramNode> DecisionDiagram<N> for BDD<N> {
+    fn all_nodes(&self) -> HashSet<&N> {
         self.graph.all_nodes()
     }
     fn len(&self) -> usize {
@@ -42,7 +41,7 @@ impl DecisionDiagram for BDD {
     }
 }
 
-impl ReducedDecisionDiagram for BDD {
+impl ReducedDecisionDiagram for BDD<Node> {
     // convert tree to BDD
     fn reduce(&mut self) {
         let root = self.graph.clone();
@@ -119,7 +118,7 @@ impl ReducedDecisionDiagram for BDD {
             .unwrap()
             .clone();
     }
-    fn apply(&self, op: Box<dyn Fn(bool, bool) -> bool>, unit: bool, other: &Self) -> BDD {
+    fn apply(&self, op: Box<dyn Fn(bool, bool) -> bool>, unit: bool, other: &Self) -> BDD<Node> {
         let mut from_index: HashMap<usize, Node> = HashMap::new();
         from_index.insert(0, Node::new_constant(false));
         from_index.insert(1, Node::new_constant(true));
@@ -269,7 +268,7 @@ mod test {
     fn test() {
         let f = Node::new_constant(false);
         let n: Node = Node::new_var(2, f.clone(), f.clone());
-        let bdd: BDD = BDD::new_from(n);
+        let bdd: BDD<Node> = BDD::new_from(n);
         assert_eq!(bdd.len(), 1);
     }
 }

src/main.rs

@@ -26,13 +26,13 @@ fn main() {
         .write_as_gv(f4)
         .expect("fail to serialize");
 
-    let x1x3: BDD = BDD::new_from(example::x1x3());
+    let x1x3: BDD<Node> = BDD::new_from(example::x1x3());
     let x1x3f = File::create("x1x2-bdd.gv").expect("fail to create");
     x1x3.write_as_gv(x1x3f).expect("fail to save");
-    let x2x3: BDD = BDD::new_from(example::x2x3());
+    let x2x3: BDD<Node> = BDD::new_from(example::x2x3());
     let x2x3f = File::create("x2x3-bdd.gv").expect("fail to create");
     x2x3.write_as_gv(x2x3f).expect("fail to save");
-    let applied: BDD = x1x3.apply(Box::new(|a, b| a | b), true, &x2x3);
+    let applied: BDD<Node> = x1x3.apply(Box::new(|a, b| a | b), true, &x2x3);
     let applyf = File::create("apply-bdd.gv").expect("fail to create");
     applied.write_as_gv(applyf).expect("fail to save");
 }

src/node.rs

@@ -41,12 +41,11 @@ impl Default for Vertex {
     }
 }
 
-impl DecisionDiagram for Node {
-    type Element = Node;
+impl DecisionDiagram<Node> for Node {
     /// returns the number of nodes under self and self itself.
     ///```
-    /// use ddir::dd::DecisionDiagram;
-    /// use ddir::node::{DecisionDiagramNode, Node};
+    /// use ddir::node::Node;
+    /// use ddir::types::{DecisionDiagram, DecisionDiagramNode};
     ///
     /// let f = Node::new_constant(false);
     /// assert_eq!(f.len(), 1);
@@ -60,8 +59,8 @@ impl DecisionDiagram for Node {
     }
     /// returns all nodes under self and self itself.
     ///```
-    /// use ddir::dd::DecisionDiagram;
-    /// use ddir::node::{DecisionDiagramNode, Node};
+    /// use ddir::node::Node;
+    /// use ddir::types::{DecisionDiagram, DecisionDiagramNode};
     ///
     /// let f = Node::new_constant(false);
     /// let n = Node::new_var(2, f.clone(), f.clone());
@@ -160,8 +159,8 @@ impl DecisionDiagramNode for Node {
     }
     /// returns `None` if self is a non-terminal node.
     ///```
-    /// use ddir::dd::DecisionDiagram;
-    /// use ddir::node::{DecisionDiagramNode, Node};
+    /// use ddir::node::Node;
+    /// use ddir::types::{DecisionDiagram, DecisionDiagramNode};
     ///
     /// let f = Node::new_constant(false);
     /// assert!(f.is_constant().is_some());
@@ -180,8 +179,8 @@ impl DecisionDiagramNode for Node {
     }
     /// returns the number of nodes under self and self itself.
     ///```
-    /// use ddir::dd::DecisionDiagram;
-    /// use ddir::node::{DecisionDiagramNode, Node};
+    /// use ddir::node::Node;
+    /// use ddir::types::{DecisionDiagram, DecisionDiagramNode};
     ///
     /// let f = Node::new_constant(false);
     /// let n = Node::new_var(2, f.clone(), f.clone());

src/types.rs

@@ -1,12 +1,11 @@
 //! Types and traits
-use std::{collections::HashSet, io};
+use std::{collections::HashSet, hash::Hash, io};
 
 pub(crate) type BooleanOperator = (Box<dyn Fn(bool, bool) -> bool>, bool);
 
-pub trait DecisionDiagram {
-    type Element;
+pub trait DecisionDiagram<N: DecisionDiagramNode> {
     // return the hashset of all (non)terminal nodes in graph.
-    fn all_nodes(&self) -> HashSet<&Self::Element>;
+    fn all_nodes(&self) -> HashSet<&N>;
     // return the number of (non)terminal nodes in graph.
     fn len(&self) -> usize;
     fn is_empty(&self) -> bool {
@@ -16,16 +15,19 @@ pub trait DecisionDiagram {
     fn write_as_gv(&self, sink: impl io::Write) -> io::Result<()>;
 }
 
-pub trait DecisionDiagramNode {
-    // return a new terminal node
+pub trait DecisionDiagramNode: Clone + Default + Eq + Hash {
+    /// return a new terminal node
     fn new_constant(b: bool) -> Self;
-    // return a new non-terminal node
+    /// return a new non-terminal node
     fn new_var(var_index: usize, low: Self, high: Self) -> Self;
     fn is_constant(&self) -> Option<bool>;
-    // return 0 or 1 for terminal nodes, and `vi + 2` for nonterminal node which var_index is `vi`.
+    /// return 0 or 1 for terminal nodes, and `vi + 2` for nonterminal node which var_index is `vi`.
     fn unified_key(&self) -> usize;
+    /// return the decision var
     fn var_index(&self) -> Option<usize>;
+    /// return the node element for the decision var == false
     fn low(&self) -> Option<&Self>;
+    /// return the node element for the decision var == true
     fn high(&self) -> Option<&Self>;
 }
 

src/zdd.rs

@@ -1,20 +1,21 @@
 //! Zero-suppressed Decision Diagram
+
 use {
     crate::{
         node::Node,
-        types::{DecisionDiagram, ReducedDecisionDiagram},
+        types::{DecisionDiagram, DecisionDiagramNode, ReducedDecisionDiagram},
     },
     std::{collections::HashSet, io, marker::PhantomData},
 };
 
 #[derive(Clone, Debug, Default, Eq, Hash, PartialEq)]
-pub struct ZDD {
-    graph: Node,
+pub struct ZDD<N> {
+    graph: N,
     phantom: PhantomData<()>,
 }
 
-impl ZDD {
-    pub fn new_from(graph: Node) -> ZDD {
+impl ZDD<Node> {
+    pub fn new_from(graph: Node) -> ZDD<Node> {
         let mut zdd = ZDD {
             graph: graph.clone(),
             ..Default::default()
@@ -24,9 +25,8 @@ impl ZDD {
     }
 }
 
-impl DecisionDiagram for ZDD {
-    type Element = Node;
-    fn all_nodes(&self) -> HashSet<&Node> {
+impl<N: DecisionDiagram<N> + DecisionDiagramNode> DecisionDiagram<N> for ZDD<N> {
+    fn all_nodes(&self) -> HashSet<&N> {
         self.graph.all_nodes()
     }
     fn len(&self) -> usize {
@@ -37,7 +37,7 @@ impl DecisionDiagram for ZDD {
     }
 }
 
-impl ReducedDecisionDiagram for ZDD {
+impl ReducedDecisionDiagram for ZDD<Node> {
     fn reduce(&mut self) {
         todo!()
     }