Add type alias for the return type

Author: yancyribbens

src/branch_and_bound.rs

@@ -7,7 +7,7 @@
 use bitcoin::amount::CheckedSum;
 use bitcoin::{Amount, FeeRate, SignedAmount};
 
-use crate::WeightedUtxo;
+use crate::{Return, WeightedUtxo};
 
 /// Performs a deterministic depth first branch and bound search for a changeless solution.
 ///
@@ -152,7 +152,7 @@ pub fn select_coins_bnb<Utxo: WeightedUtxo>(
     fee_rate: FeeRate,
     long_term_fee_rate: FeeRate,
     weighted_utxos: &[Utxo],
-) -> Option<(u32, Vec<&Utxo>)> {
+) -> Return<Utxo> {
     // Total_Tries in Core:
     // https://github.com/bitcoin/bitcoin/blob/1d9da8da309d1dbf9aef15eb8dc43b4a2dc3d309/src/wallet/coinselection.cpp#L74
     const ITERATION_LIMIT: u32 = 100_000;

src/lib.rs

@@ -20,6 +20,8 @@ use rand::thread_rng;
 pub use crate::branch_and_bound::select_coins_bnb;
 pub use crate::single_random_draw::select_coins_srd;
 
+pub(crate) type Return<'a, Utxo> = Option<(u32, Vec<&'a Utxo>)>;
+
 // https://github.com/bitcoin/bitcoin/blob/f722a9bd132222d9d5cd503b5af25c905b205cdb/src/wallet/coinselection.h#L20
 const CHANGE_LOWER: Amount = Amount::from_sat(50_000);
 
@@ -114,7 +116,7 @@ pub fn select_coins<Utxo: WeightedUtxo>(
     fee_rate: FeeRate,
     long_term_fee_rate: FeeRate,
     weighted_utxos: &[Utxo],
-) -> Option<(u32, Vec<&Utxo>)> {
+) -> Return<Utxo> {
     let bnb =
         select_coins_bnb(target, cost_of_change, fee_rate, long_term_fee_rate, weighted_utxos);
 

src/single_random_draw.rs

@@ -8,7 +8,7 @@ use bitcoin::blockdata::transaction::effective_value;
 use bitcoin::{Amount, FeeRate};
 use rand::seq::SliceRandom;
 
-use crate::{WeightedUtxo, CHANGE_LOWER};
+use crate::{Return, WeightedUtxo, CHANGE_LOWER};
 
 /// Randomize the input set and select coins until the target is reached.
 ///
@@ -38,7 +38,7 @@ pub fn select_coins_srd<'a, R: rand::Rng + ?Sized, Utxo: WeightedUtxo>(
     fee_rate: FeeRate,
     weighted_utxos: &'a [Utxo],
     rng: &mut R,
-) -> Option<(u32, Vec<&'a Utxo>)> {
+) -> Return<'a, Utxo> {
     if target > Amount::MAX_MONEY {
         return None;
     }