ref(chain): move keychain::ChangeSet into txout_index.rs

We plan to record `Descriptor` additions into persistence. Hence, we
need to add `Descriptor`s to the changeset. This depends on
`miniscript`. Moving this into `txout_index.rs` makes sense as this is
consistent with all the other files. The only reason why this wasn't
this way before, is because the changeset didn't need miniscript.

Co-Authored-By: Daniela Brozzoni <danielabrozzoni@protonmail.com>

crates/chain/src/indexed_tx_graph.rs

@@ -320,6 +320,7 @@ impl<A, IA: Default> From<tx_graph::ChangeSet<A>> for ChangeSet<A, IA> {
     }
 }
 
+#[cfg(feature = "miniscript")]
 impl<A, K> From<keychain::ChangeSet<K>> for ChangeSet<A, keychain::ChangeSet<K>> {
     fn from(indexer: keychain::ChangeSet<K>) -> Self {
         Self {

crates/chain/src/keychain.rs

@@ -10,78 +10,12 @@
 //!
 //! [`SpkTxOutIndex`]: crate::SpkTxOutIndex
 
-use crate::{collections::BTreeMap, Append};
-
 #[cfg(feature = "miniscript")]
 mod txout_index;
 use bitcoin::Amount;
 #[cfg(feature = "miniscript")]
 pub use txout_index::*;
 
-/// Represents updates to the derivation index of a [`KeychainTxOutIndex`].
-/// It maps each keychain `K` to its last revealed index.
-///
-/// It can be applied to [`KeychainTxOutIndex`] with [`apply_changeset`]. [`ChangeSet`]s are
-/// monotone in that they will never decrease the revealed derivation index.
-///
-/// [`KeychainTxOutIndex`]: crate::keychain::KeychainTxOutIndex
-/// [`apply_changeset`]: crate::keychain::KeychainTxOutIndex::apply_changeset
-#[derive(Clone, Debug, PartialEq)]
-#[cfg_attr(
-    feature = "serde",
-    derive(serde::Deserialize, serde::Serialize),
-    serde(
-        crate = "serde_crate",
-        bound(
-            deserialize = "K: Ord + serde::Deserialize<'de>",
-            serialize = "K: Ord + serde::Serialize"
-        )
-    )
-)]
-#[must_use]
-pub struct ChangeSet<K>(pub BTreeMap<K, u32>);
-
-impl<K> ChangeSet<K> {
-    /// Get the inner map of the keychain to its new derivation index.
-    pub fn as_inner(&self) -> &BTreeMap<K, u32> {
-        &self.0
-    }
-}
-
-impl<K: Ord> Append for ChangeSet<K> {
-    /// Append another [`ChangeSet`] into self.
-    ///
-    /// If the keychain already exists, increase the index when the other's index > self's index.
-    /// If the keychain did not exist, append the new keychain.
-    fn append(&mut self, mut other: Self) {
-        self.0.iter_mut().for_each(|(key, index)| {
-            if let Some(other_index) = other.0.remove(key) {
-                *index = other_index.max(*index);
-            }
-        });
-        // We use `extend` instead of `BTreeMap::append` due to performance issues with `append`.
-        // Refer to https://github.com/rust-lang/rust/issues/34666#issuecomment-675658420
-        self.0.extend(other.0);
-    }
-
-    /// Returns whether the changeset are empty.
-    fn is_empty(&self) -> bool {
-        self.0.is_empty()
-    }
-}
-
-impl<K> Default for ChangeSet<K> {
-    fn default() -> Self {
-        Self(Default::default())
-    }
-}
-
-impl<K> AsRef<BTreeMap<K, u32>> for ChangeSet<K> {
-    fn as_ref(&self) -> &BTreeMap<K, u32> {
-        &self.0
-    }
-}
-
 /// Balance, differentiated into various categories.
 #[derive(Debug, PartialEq, Eq, Clone, Default)]
 #[cfg_attr(
@@ -137,40 +71,3 @@ impl core::ops::Add for Balance {
         }
     }
 }
-
-#[cfg(test)]
-mod test {
-    use super::*;
-
-    #[test]
-    fn append_keychain_derivation_indices() {
-        #[derive(Ord, PartialOrd, Eq, PartialEq, Clone, Debug)]
-        enum Keychain {
-            One,
-            Two,
-            Three,
-            Four,
-        }
-        let mut lhs_di = BTreeMap::<Keychain, u32>::default();
-        let mut rhs_di = BTreeMap::<Keychain, u32>::default();
-        lhs_di.insert(Keychain::One, 7);
-        lhs_di.insert(Keychain::Two, 0);
-        rhs_di.insert(Keychain::One, 3);
-        rhs_di.insert(Keychain::Two, 5);
-        lhs_di.insert(Keychain::Three, 3);
-        rhs_di.insert(Keychain::Four, 4);
-
-        let mut lhs = ChangeSet(lhs_di);
-        let rhs = ChangeSet(rhs_di);
-        lhs.append(rhs);
-
-        // Exiting index doesn't update if the new index in `other` is lower than `self`.
-        assert_eq!(lhs.0.get(&Keychain::One), Some(&7));
-        // Existing index updates if the new index in `other` is higher than `self`.
-        assert_eq!(lhs.0.get(&Keychain::Two), Some(&5));
-        // Existing index is unchanged if keychain doesn't exist in `other`.
-        assert_eq!(lhs.0.get(&Keychain::Three), Some(&3));
-        // New keychain gets added if the keychain is in `other` but not in `self`.
-        assert_eq!(lhs.0.get(&Keychain::Four), Some(&4));
-    }
-}

crates/chain/src/keychain/txout_index.rs

@@ -13,6 +13,71 @@ use core::{
 
 use crate::Append;
 
+
+/// Represents updates to the derivation index of a [`KeychainTxOutIndex`].
+/// It maps each keychain `K` to its last revealed index.
+///
+/// It can be applied to [`KeychainTxOutIndex`] with [`apply_changeset`]. [`ChangeSet] are
+/// monotone in that they will never decrease the revealed derivation index.
+///
+/// [`KeychainTxOutIndex`]: crate::keychain::KeychainTxOutIndex
+/// [`apply_changeset`]: crate::keychain::KeychainTxOutIndex::apply_changeset
+#[derive(Clone, Debug, PartialEq)]
+#[cfg_attr(
+    feature = "serde",
+    derive(serde::Deserialize, serde::Serialize),
+    serde(
+        crate = "serde_crate",
+        bound(
+            deserialize = "K: Ord + serde::Deserialize<'de>",
+            serialize = "K: Ord + serde::Serialize"
+        )
+    )
+)]
+#[must_use]
+pub struct ChangeSet<K>(pub BTreeMap<K, u32>);
+
+impl<K> ChangeSet<K> {
+    /// Get the inner map of the keychain to its new derivation index.
+    pub fn as_inner(&self) -> &BTreeMap<K, u32> {
+        &self.0
+    }
+}
+
+impl<K: Ord> Append for ChangeSet<K> {
+    /// Append another [`ChangeSet`] into self.
+    ///
+    /// If the keychain already exists, increase the index when the other's index > self's index.
+    /// If the keychain did not exist, append the new keychain.
+    fn append(&mut self, mut other: Self) {
+        self.0.iter_mut().for_each(|(key, index)| {
+            if let Some(other_index) = other.0.remove(key) {
+                *index = other_index.max(*index);
+            }
+        });
+        // We use `extend` instead of `BTreeMap::append` due to performance issues with `append`.
+        // Refer to https://github.com/rust-lang/rust/issues/34666#issuecomment-675658420
+        self.0.extend(other.0);
+    }
+
+    /// Returns whether the changeset are empty.
+    fn is_empty(&self) -> bool {
+        self.0.is_empty()
+    }
+}
+
+impl<K> Default for ChangeSet<K> {
+    fn default() -> Self {
+        Self(Default::default())
+    }
+}
+
+impl<K> AsRef<BTreeMap<K, u32>> for ChangeSet<K> {
+    fn as_ref(&self) -> &BTreeMap<K, u32> {
+        &self.0
+    }
+}
+
 const DEFAULT_LOOKAHEAD: u32 = 25;
 
 /// [`KeychainTxOutIndex`] controls how script pubkeys are revealed for multiple keychains, and

crates/chain/tests/test_keychain_txout_index.rs

@@ -5,7 +5,7 @@ mod common;
 use bdk_chain::{
     collections::BTreeMap,
     indexed_tx_graph::Indexer,
-    keychain::{self, KeychainTxOutIndex},
+    keychain::{self, ChangeSet, KeychainTxOutIndex},
     Append,
 };
 
@@ -44,6 +44,38 @@ fn spk_at_index(descriptor: &Descriptor<DescriptorPublicKey>, index: u32) -> Scr
         .script_pubkey()
 }
 
+#[test]
+fn append_keychain_derivation_indices() {
+    #[derive(Ord, PartialOrd, Eq, PartialEq, Clone, Debug)]
+    enum Keychain {
+        One,
+        Two,
+        Three,
+        Four,
+    }
+    let mut lhs_di = BTreeMap::<Keychain, u32>::default();
+    let mut rhs_di = BTreeMap::<Keychain, u32>::default();
+    lhs_di.insert(Keychain::One, 7);
+    lhs_di.insert(Keychain::Two, 0);
+    rhs_di.insert(Keychain::One, 3);
+    rhs_di.insert(Keychain::Two, 5);
+    lhs_di.insert(Keychain::Three, 3);
+    rhs_di.insert(Keychain::Four, 4);
+
+    let mut lhs = ChangeSet(lhs_di);
+    let rhs = ChangeSet(rhs_di);
+    lhs.append(rhs);
+
+    // Exiting index doesn't update if the new index in `other` is lower than `self`.
+    assert_eq!(lhs.0.get(&Keychain::One), Some(&7));
+    // Existing index updates if the new index in `other` is higher than `self`.
+    assert_eq!(lhs.0.get(&Keychain::Two), Some(&5));
+    // Existing index is unchanged if keychain doesn't exist in `other`.
+    assert_eq!(lhs.0.get(&Keychain::Three), Some(&3));
+    // New keychain gets added if the keychain is in `other` but not in `self`.
+    assert_eq!(lhs.0.get(&Keychain::Four), Some(&4));
+}
+
 #[test]
 fn test_set_all_derivation_indices() {
     use bdk_chain::indexed_tx_graph::Indexer;