From 7703a673ea73301027988d77d8a70cb613501cb5 Mon Sep 17 00:00:00 2001
From: Sean Bowe <ewillbefull@gmail.com>
Date: Fri, 27 Apr 2018 16:52:33 -0600
Subject: [PATCH] Generalize the PushAnchor implementation behavior.

---
 src/coins.cpp | 28 ++++++++++++++++++++++------
 src/coins.h   |  9 +++++++++
 2 files changed, 31 insertions(+), 6 deletions(-)

diff --git a/src/coins.cpp b/src/coins.cpp
index a6c43ce6b..7f400ed44 100644
--- a/src/coins.cpp
+++ b/src/coins.cpp
@@ -160,10 +160,17 @@ bool CCoinsViewCache::GetNullifier(const uint256 &nullifier, ShieldedType type)
     return tmp;
 }
 
-void CCoinsViewCache::PushSproutAnchor(const ZCIncrementalMerkleTree &tree) {
+template<typename Tree, typename Cache, typename CacheIterator, typename CacheEntry>
+void CCoinsViewCache::AbstractPushAnchor(
+    const Tree &tree,
+    ShieldedType type,
+    Cache &cacheAnchors,
+    uint256 &hash
+)
+{
     uint256 newrt = tree.root();
 
-    auto currentRoot = GetBestAnchor(SPROUT);
+    auto currentRoot = GetBestAnchor(type);
 
     // We don't want to overwrite an anchor we already have.
     // This occurs when a block doesn't modify mapSproutAnchors at all,
@@ -171,22 +178,31 @@ void CCoinsViewCache::PushSproutAnchor(const ZCIncrementalMerkleTree &tree) {
     // different way (make all blocks modify mapSproutAnchors somehow)
     // but this is simpler to reason about.
     if (currentRoot != newrt) {
-        auto insertRet = cacheSproutAnchors.insert(std::make_pair(newrt, CAnchorsSproutCacheEntry()));
-        CAnchorsSproutMap::iterator ret = insertRet.first;
+        auto insertRet = cacheAnchors.insert(std::make_pair(newrt, CacheEntry()));
+        CacheIterator ret = insertRet.first;
 
         ret->second.entered = true;
         ret->second.tree = tree;
-        ret->second.flags = CAnchorsSproutCacheEntry::DIRTY;
+        ret->second.flags = CacheEntry::DIRTY;
 
         if (insertRet.second) {
             // An insert took place
             cachedCoinsUsage += ret->second.tree.DynamicMemoryUsage();
         }
 
-        hashSproutAnchor = newrt;
+        hash = newrt;
     }
 }
 
+void CCoinsViewCache::PushSproutAnchor(const ZCIncrementalMerkleTree &tree) {
+    AbstractPushAnchor<ZCIncrementalMerkleTree, CAnchorsSproutMap, CAnchorsSproutMap::iterator, CAnchorsSproutCacheEntry>(
+        tree,
+        SPROUT,
+        cacheSproutAnchors,
+        hashSproutAnchor
+    );
+}
+
 template<typename Tree, typename Cache, typename CacheEntry>
 void CCoinsViewCache::AbstractPopAnchor(
     const uint256 &newrt,
diff --git a/src/coins.h b/src/coins.h
index f121ed2e7..b8c41e5d7 100644
--- a/src/coins.h
+++ b/src/coins.h
@@ -533,6 +533,15 @@ private:
         Cache &cacheAnchors,
         uint256 &hash
     );
+
+    //! Generalized interface for pushing anchors
+    template<typename Tree, typename Cache, typename CacheIterator, typename CacheEntry>
+    void AbstractPushAnchor(
+        const Tree &tree,
+        ShieldedType type,
+        Cache &cacheAnchors,
+        uint256 &hash
+    );
 };
 
 #endif // BITCOIN_COINS_H