Impl Serialize for TreeDecomposition

src/pace/parameters/tree_decomposition.rs

@@ -1,4 +1,6 @@
 use serde::de::{self, Deserialize, Deserializer, SeqAccess, Visitor};
+use serde::ser::SerializeSeq;
+use serde::{Serialize, Serializer};
 use std::fmt;
 
 type Node = u32;
@@ -13,6 +15,22 @@ pub struct TreeDecomposition {
     pub edges: Vec<(Node, Node)>,
 }
 
+impl Serialize for TreeDecomposition {
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: Serializer,
+    {
+        // 3-element tuple
+        let mut seq = serializer.serialize_seq(Some(3))?;
+
+        seq.serialize_element(&self.treewidth)?;
+        seq.serialize_element(&self.bags)?;
+        seq.serialize_element(&self.edges)?;
+
+        seq.end()
+    }
+}
+
 impl<'de> Deserialize<'de> for TreeDecomposition {
     fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
     where
@@ -58,14 +76,22 @@ impl<'de> Deserialize<'de> for TreeDecomposition {
 #[cfg(test)]
 mod test {
     use crate::pace::parameters::tree_decomposition::TreeDecomposition;
+    const JSON: &str = "[2,[[8,16],[8,11,16],[1,11,15],[2,11,16],[7,8,11],[8,10,16],[3,10,13],[4,10,16],[8,9],[5,9,14],[6,9,12]],[[1,2],[1,6],[1,9],[2,3],[2,4],[2,5],[6,7],[6,8],[9,10],[9,11]]]";
 
     #[test]
-    fn json_to_tree_decomp() {
-        const JSON: &str = "[2,[[8,16],[8,11,16],[1,11,15],[2,11,16],[7,8,11],[8,10,16],[3,10,13],[4,10,16],[8,9],[5,9,14],[6,9,12]],[[1,2],[1,6],[1,9],[2,3],[2,4],[2,5],[6,7],[6,8],[9,10],[9,11]]]";
+    fn deserialize() {
         let td: TreeDecomposition = serde_json::from_str(JSON).unwrap();
 
         assert_eq!(td.treewidth, 2);
         assert_eq!(td.bags.len(), 11);
         assert_eq!(td.edges.len(), 10);
     }
+
+    #[test]
+    fn serialize() {
+        let td: TreeDecomposition = serde_json::from_str(JSON).unwrap();
+        let serialized = serde_json::to_string(&td).unwrap();
+
+        assert_eq!(serialized, JSON);
+    }
 }