Merge rust-bitcoin/rust-bitcoin#927: Trivial improvements for TapTree type

4cdff06 Add convenience method TapTree:to_builder (Dr Maxim Orlovsky)
a12e7c7 Implement From<TapTree> for TaprootBuilder (Dr Maxim Orlovsky)
410412f Rename TapTree::from_builder (Dr Maxim Orlovsky)
2192737 Rename TapTree::into_builder (Dr Maxim Orlovsky)
f9d8d0d Make TapTree::node_info public (Dr Maxim Orlovsky)

Pull request description:

  These are trivial fixes from extracted from now closed #922

ACKs for top commit:
  Kixunil:
    ACK 4cdff06
  sanket1729:
    ACK 4cdff06
  apoelstra:
    ACK 4cdff06

Tree-SHA512: 6132e8c214edc6f199a5550309daf4ed5035f24f545c793d6396c393bd2f55940dc418af62aed9aff25c0c90b74ee384ace986f7201db4018c6fd52710006126

Author: apoelstra

src/util/psbt/map/output.rs

@@ -125,36 +125,49 @@ impl PartialEq for TapTree {
 
 impl Eq for TapTree {}
 
+impl From<TapTree> for TaprootBuilder {
+    #[inline]
+    fn from(tree: TapTree) -> Self {
+        tree.into_builder()
+    }
+}
+
 impl TapTree {
     /// Gets the inner node info as the builder is finalized.
-    fn node_info(&self) -> &NodeInfo {
+    pub fn node_info(&self) -> &NodeInfo {
         // The builder algorithm invariant guarantees that is_complete builder
         // have only 1 element in branch and that is not None.
         // We make sure that we only allow is_complete builders via the from_inner
         // constructor
         self.0.branch()[0].as_ref().expect("from_inner only parses is_complete builders")
     }
 
-    /// Converts a [`TaprootBuilder`] into a tree if it is complete binary tree.
+    /// Constructs [`TapTree`] from a [`TaprootBuilder`] if it is complete binary tree.
     ///
     /// # Returns
-    /// A [`TapTree`] iff the `inner` builder is complete, otherwise return [`IncompleteTapTree`]
-    /// error with the content of incomplete builder `inner` instance.
-    pub fn from_inner(inner: TaprootBuilder) -> Result<Self, IncompleteTapTree> {
-        if !inner.is_finalized() {
-            Err(IncompleteTapTree::NotFinalized(inner))
-        } else if inner.has_hidden_nodes() {
-            Err(IncompleteTapTree::HiddenParts(inner))
+    /// A [`TapTree`] iff the `builder` is complete, otherwise return [`IncompleteTapTree`]
+    /// error with the content of incomplete `builder` instance.
+    pub fn from_builder(builder: TaprootBuilder) -> Result<Self, IncompleteTapTree> {
+        if !builder.is_finalized() {
+            Err(IncompleteTapTree::NotFinalized(builder))
+        } else if builder.has_hidden_nodes() {
+            Err(IncompleteTapTree::HiddenParts(builder))
         } else {
-            Ok(TapTree(inner))
+            Ok(TapTree(builder))
         }
     }
 
     /// Converts self into builder [`TaprootBuilder`]. The builder is guaranteed to be finalized.
-    pub fn into_inner(self) -> TaprootBuilder {
+    pub fn into_builder(self) -> TaprootBuilder {
         self.0
     }
 
+    /// Constructs [`TaprootBuilder`] by internally cloning the `self`. The builder is guaranteed
+    /// to be finalized.
+    pub fn to_builder(&self) -> TaprootBuilder {
+        self.0.clone()
+    }
+
     /// Returns [`TapTreeIter`] iterator for a taproot script tree, operating in DFS order over
     /// tree [`ScriptLeaf`]s.
     pub fn script_leaves(&self) -> TapTreeIter {

src/util/psbt/serialize.rs

@@ -393,14 +393,14 @@ mod tests {
         let mut builder = compose_taproot_builder(0x51, &[2, 2, 2]);
         builder = builder.add_leaf_with_ver(3, Script::from_hex("b9").unwrap(), LeafVersion::from_consensus(0xC2).unwrap()).unwrap();
         builder = builder.add_hidden_node(3, sha256::Hash::default()).unwrap();
-        assert!(TapTree::from_inner(builder.clone()).is_err());
+        assert!(TapTree::from_builder(builder.clone()).is_err());
     }
 
     #[test]
     fn taptree_roundtrip() {
         let mut builder = compose_taproot_builder(0x51, &[2, 2, 2, 3]);
         builder = builder.add_leaf_with_ver(3, Script::from_hex("b9").unwrap(), LeafVersion::from_consensus(0xC2).unwrap()).unwrap();
-        let tree = TapTree::from_inner(builder).unwrap();
+        let tree = TapTree::from_builder(builder).unwrap();
         let tree_prime = TapTree::deserialize(&tree.serialize()).unwrap();
         assert_eq!(tree, tree_prime);
     }