Can get the taproot leafs of derived miniscript

Author: NicolasDorier

NBitcoin/WalletPolicies/DerivationResult.cs

@@ -36,5 +36,6 @@ public Derivation(KeyPath keyPath, Value pubkey)
 	/// The derived key. This is either a <see cref="Value.PubKeyValue"/> or a <see cref="Value.TaprootPubKeyValue"/>.
 	/// </summary>
 	public Value Pubkey { get; }
+	public HashSet<uint256> TaprootLeafs = new();
 }
 #endif

NBitcoin/WalletPolicies/Visitors/DeriveVisitor.cs

@@ -32,8 +32,21 @@ public DerivationResult[] Derive(MiniscriptNode node, Network network)
 	}
 
 	internal static readonly byte[] BIP0328CC = Encoders.Hex.DecodeData("868087ca02a6f974c4598924c36b57762d32cb45717167e300622c7167e38965");
+	Stack<TaprootBranchNode> _TaprootBranches = new();
 	public override MiniscriptNode Visit(MiniscriptNode node)
 	{
+		if (node is TaprootBranchNode b)
+		{
+			_TaprootBranches.Push(b);
+			try
+			{
+				return base.Visit(b);
+			}
+			finally
+			{
+				_TaprootBranches.Pop();
+			}
+		}
 		if (node is MultipathNode { Target: MusigNode })
 		{
 			var wasNestedMusig = _nestedMusig;
@@ -55,7 +68,15 @@ public override MiniscriptNode Visit(MiniscriptNode node)
 		{
 			if (mki.Target is HDKeyNode { Key: var pk } xpub)
 			{
-				var value = GetPublicKey(mki, pk);
+				if (!_Derivations.TryGetValue(xpub, out var value))
+				{
+					value = GetPublicKey(mki, pk);
+					_Derivations.Add(xpub, value);
+				}
+				if (_TaprootBranches.Count > 0)
+				{
+					value.TaprootLeafs.Add(TaprootNodeInfo.NewLeaf(new TapScript(_TaprootBranches.Peek().GetScript(), TapLeafVersion.C0)).Hash);
+				}
 				_Derivations.TryAdd(xpub, value);
 				node = value.Pubkey;
 			}