From 3991193c9847334fe889bc8da07bbf7e465522c4 Mon Sep 17 00:00:00 2001
From: "Narazaki, Shuji" <shujinarazaki@protonmail.com>
Date: Sat, 3 Feb 2024 09:09:44 +0900
Subject: [PATCH] ditto

---
 src/bdd.rs   |  9 +++++----
 src/node.rs  | 22 ++++++----------------
 src/types.rs | 28 +++++++++++++++++++++-------
 src/zdd.rs   |  1 +
 4 files changed, 33 insertions(+), 27 deletions(-)

diff --git a/src/bdd.rs b/src/bdd.rs
index 9d0bc7a..b1c4634 100644
--- a/src/bdd.rs
+++ b/src/bdd.rs
@@ -1,7 +1,8 @@
+//! Binary Decision Diagram
 use {
     crate::{
-        node::{DecisionDiagramNode, Node, Vertex},
-        types::{BooleanOperator, DecisionDiagram, ReducedDecisionDiagram},
+        node::{Node, Vertex},
+        types::{BooleanOperator, DecisionDiagram, DecisionDiagramNode, ReducedDecisionDiagram},
     },
     itertools::Itertools,
     std::{
@@ -260,8 +261,8 @@ impl ReducedDecisionDiagram for BDD {
 mod test {
     use crate::{
         bdd::BDD,
-        node::{DecisionDiagramNode, Node},
-        types::DecisionDiagram,
+        node::Node,
+        types::{DecisionDiagram, DecisionDiagramNode},
     };
 
     #[test]
diff --git a/src/node.rs b/src/node.rs
index 9c372d8..f699e80 100644
--- a/src/node.rs
+++ b/src/node.rs
@@ -1,5 +1,6 @@
+//! Element type for Decision Diagrams
 use {
-    crate::types::DecisionDiagram,
+    crate::types::{DecisionDiagram, DecisionDiagramNode},
     std::{
         collections::{HashMap, HashSet},
         hash::Hash,
@@ -10,17 +11,6 @@ use {
 
 pub type Node = Rc<Vertex>;
 
-pub trait DecisionDiagramNode {
-    fn new_constant(b: bool) -> Self;
-    fn new_var(var_index: usize, low: Node, high: Node) -> 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`.
-    fn unified_key(&self) -> usize;
-    fn var_index(&self) -> Option<usize>;
-    fn low(&self) -> Option<&Self>;
-    fn high(&self) -> Option<&Self>;
-}
-
 #[derive(Clone, Debug)]
 pub enum Vertex {
     Bool(bool),
@@ -157,11 +147,11 @@ impl DecisionDiagram for Node {
 
 impl DecisionDiagramNode for Node {
     /// returns a new terminal node.
-    fn new_constant(b: bool) -> Self {
+    fn new_constant(b: bool) -> Node {
         Rc::new(Vertex::Bool(b))
     }
     /// returns a new non-terminal node.
-    fn new_var(var_index: usize, low: Node, high: Node) -> Self {
+    fn new_var(var_index: usize, low: Node, high: Node) -> Node {
         Rc::new(Vertex::Var {
             var_index,
             low,
@@ -203,13 +193,13 @@ impl DecisionDiagramNode for Node {
             Vertex::Var { var_index, .. } => Some(var_index),
         }
     }
-    fn low(&self) -> Option<&Self> {
+    fn low(&self) -> Option<&Node> {
         match **self {
             Vertex::Bool(_) => None,
             Vertex::Var { ref low, .. } => Some(low),
         }
     }
-    fn high(&self) -> Option<&Self> {
+    fn high(&self) -> Option<&Node> {
         match **self {
             Vertex::Bool(_) => None,
             Vertex::Var { ref high, .. } => Some(high),
diff --git a/src/types.rs b/src/types.rs
index fc9cfaf..c6e6d67 100644
--- a/src/types.rs
+++ b/src/types.rs
@@ -1,14 +1,8 @@
+//! Types and traits
 use std::{collections::HashSet, io};
 
 pub(crate) type BooleanOperator = (Box<dyn Fn(bool, bool) -> bool>, bool);
 
-pub trait ReducedDecisionDiagram {
-    /// convert the current graph to one which is a reduced diagram
-    fn reduce(&mut self);
-    /// return a new graph generated by apply `op` to this and the other graph
-    fn apply(&self, op: Box<dyn Fn(bool, bool) -> bool>, unit: bool, _other: &Self) -> Self;
-}
-
 pub trait DecisionDiagram {
     type Element;
     // return the hashset of all (non)terminal nodes in graph.
@@ -21,3 +15,23 @@ pub trait DecisionDiagram {
     // write the graph in graphvis format
     fn write_as_gv(&self, sink: impl io::Write) -> io::Result<()>;
 }
+
+pub trait DecisionDiagramNode {
+    // return a new terminal node
+    fn new_constant(b: bool) -> Self;
+    // 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`.
+    fn unified_key(&self) -> usize;
+    fn var_index(&self) -> Option<usize>;
+    fn low(&self) -> Option<&Self>;
+    fn high(&self) -> Option<&Self>;
+}
+
+pub trait ReducedDecisionDiagram {
+    /// convert the current graph to one which is a reduced diagram
+    fn reduce(&mut self);
+    /// return a new graph generated by apply `op` to this and the other graph
+    fn apply(&self, op: Box<dyn Fn(bool, bool) -> bool>, unit: bool, _other: &Self) -> Self;
+}
diff --git a/src/zdd.rs b/src/zdd.rs
index 586285a..cb3cb7c 100644
--- a/src/zdd.rs
+++ b/src/zdd.rs
@@ -1,3 +1,4 @@
+//! Zero-suppressed Decision Diagram
 use {
     crate::{
         node::Node,