Split out merkle_branch(size_t position, hashes&& leaves).

Author: evoskuil

include/bitcoin/system/chain/block.hpp

@@ -43,6 +43,7 @@ class BC_API block
     typedef std::shared_ptr<const block> cptr;
 
     static bool is_malleable64(const transaction_cptrs& txs) NOEXCEPT;
+    static hashes merkle_branch(size_t position, hashes&& leaves) NOEXCEPT;
     static uint64_t subsidy(size_t height, uint64_t subsidy_interval,
         uint64_t initial_block_subsidy_satoshi, bool bip42) NOEXCEPT;
 

src/chain/block.cpp

@@ -444,24 +444,29 @@ bool block::is_invalid_merkle_root() const NOEXCEPT
     return generate_merkle_root(false) != header_->merkle_root();
 }
 
-hashes block::merkle_branch(size_t position, bool witness) const NOEXCEPT
+// static
+hashes block::merkle_branch(size_t position, hashes&& leaves) NOEXCEPT
 {
-    auto level = transaction_hashes(witness);
-    if (position >= level.size())
+    if (position >= leaves.size())
         return {};
 
     hashes branch{};
-    branch.reserve(ceilinged_log2(level.size()));
-    for (auto at = position; level.size() > one; at = to_half(at))
+    branch.reserve(ceilinged_log2(leaves.size()));
+    for (auto at = position; leaves.size() > one; at = to_half(at))
     {
-        if (is_odd(level.size())) level.push_back(level.back());
-        branch.push_back(level.at(is_even(at) ? add1(at) : sub1(at)));
-        sha256::merkle_hash(level);
+        if (is_odd(leaves.size())) leaves.push_back(leaves.back());
+        branch.push_back(leaves.at(is_even(at) ? add1(at) : sub1(at)));
+        sha256::merkle_hash(leaves);
     }
 
     return branch;
 }
 
+hashes block::merkle_branch(size_t position, bool witness) const NOEXCEPT
+{
+    return merkle_branch(position, transaction_hashes(witness));
+}
+
 // Accept (contextual).
 // ----------------------------------------------------------------------------