Add TaprootBuilder::GetTreeTuples

GetTreeTuples returns the leaves in DFS order as tuples of depth, leaf
version, and script. This is a representation of the tree that can be
serialized.

Author: achow101

src/script/standard.cpp

@@ -642,3 +642,19 @@ std::optional<std::vector<std::tuple<int, CScript, int>>> InferTaprootTree(const
 
     return ret;
 }
+
+std::vector<std::tuple<uint8_t, uint8_t, CScript>> TaprootBuilder::GetTreeTuples() const
+{
+    assert(IsComplete());
+    std::vector<std::tuple<uint8_t, uint8_t, CScript>> tuples;
+    if (m_branch.size()) {
+        const auto& leaves = m_branch[0]->leaves;
+        for (const auto& leaf : leaves) {
+            assert(leaf.merkle_branch.size() <= TAPROOT_CONTROL_MAX_NODE_COUNT);
+            uint8_t depth = (uint8_t)leaf.merkle_branch.size();
+            uint8_t leaf_ver = (uint8_t)leaf.leaf_version;
+            tuples.push_back(std::make_tuple(depth, leaf_ver, leaf.script));
+        }
+    }
+    return tuples;
+}

src/script/standard.h

@@ -322,6 +322,8 @@ class TaprootBuilder
     static bool ValidDepths(const std::vector<int>& depths);
     /** Compute spending data (after Finalize()). */
     TaprootSpendData GetSpendData() const;
+    /** Returns a vector of tuples representing the depth, leaf version, and script */
+    std::vector<std::tuple<uint8_t, uint8_t, CScript>> GetTreeTuples() const;
 };
 
 /** Given a TaprootSpendData and the output key, reconstruct its script tree.