TransactionBuilder with support for creating Sapling-only transactions

src/transaction_builder.h

@@ -0,0 +1,73 @@
+// Copyright (c) 2018 The Zcash developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef TRANSACTION_BUILDER_H
+#define TRANSACTION_BUILDER_H
+
+#include "consensus/params.h"
+#include "primitives/transaction.h"
+#include "uint256.h"
+#include "zcash/Address.hpp"
+#include "zcash/IncrementalMerkleTree.hpp"
+#include "zcash/Note.hpp"
+#include "zcash/NoteEncryption.hpp"
+
+#include <boost/optional.hpp>
+
+struct SpendDescriptionInfo
+{
+    libzcash::SaplingExpandedSpendingKey xsk;
+    libzcash::SaplingNote note;
+    uint256 alpha;
+    uint256 anchor;
+    ZCSaplingIncrementalWitness witness;
+
+    SpendDescriptionInfo(
+        libzcash::SaplingExpandedSpendingKey xsk,
+        libzcash::SaplingNote note,
+        uint256 anchor,
+        ZCSaplingIncrementalWitness witness);
+};
+
+struct OutputDescriptionInfo
+{
+    uint256 ovk;
+    libzcash::SaplingNote note;
+    std::array<unsigned char, ZC_MEMO_SIZE> memo;
+
+    OutputDescriptionInfo(
+        uint256 ovk,
+        libzcash::SaplingNote note,
+        std::array<unsigned char, ZC_MEMO_SIZE> memo) : ovk(ovk), note(note), memo(memo) {}
+};
+
+class TransactionBuilder
+{
+private:
+    Consensus::Params consensusParams;
+    int nHeight;
+    CMutableTransaction mtx;
+
+    std::vector<SpendDescriptionInfo> spends;
+    std::vector<OutputDescriptionInfo> outputs;
+
+public:
+    TransactionBuilder(const Consensus::Params& consensusParams, int nHeight);
+
+    void AddSaplingSpend(
+        libzcash::SaplingExpandedSpendingKey xsk,
+        libzcash::SaplingNote note,
+        uint256 anchor,
+        ZCSaplingIncrementalWitness witness);
+
+    void AddSaplingOutput(
+        libzcash::SaplingFullViewingKey from,
+        libzcash::SaplingPaymentAddress to,
+        CAmount value,
+        std::array<unsigned char, ZC_MEMO_SIZE> memo);
+
+    boost::optional<CTransaction> Build();
+};
+
+#endif /* TRANSACTION_BUILDER_H */