Move Taproot{SpendData/Builder} to signingprovider.{h/cpp}

TaprootSpendData and TaprootBuilder are used in signing in
SigningProvider contexts, so they should live near that.

1 files changed, 0 insertions, 132 deletions

diff --git a/src/script/standard.h b/src/script/standard.h
index 8a76606082..9555cc2b61 100644
--- a/src/script/standard.h
+++ b/src/script/standard.h
@@ -175,136 +175,4 @@ std::optional<std::pair<int, std::vector<Span<const unsigned char>>>> MatchMulti
 /** Generate a multisig script. */
 CScript GetScriptForMultisig(int nRequired, const std::vector<CPubKey>& keys);
 
-struct ShortestVectorFirstComparator
-{
-    bool operator()(const std::vector<unsigned char>& a, const std::vector<unsigned char>& b) const
-    {
-        if (a.size() < b.size()) return true;
-        if (a.size() > b.size()) return false;
-        return a < b;
-    }
-};
-
-struct TaprootSpendData
-{
-    /** The BIP341 internal key. */
-    XOnlyPubKey internal_key;
-    /** The Merkle root of the script tree (0 if no scripts). */
-    uint256 merkle_root;
-    /** Map from (script, leaf_version) to (sets of) control blocks.
-     *  More than one control block for a given script is only possible if it
-     *  appears in multiple branches of the tree. We keep them all so that
-     *  inference can reconstruct the full tree. Within each set, the control
-     *  blocks are sorted by size, so that the signing logic can easily
-     *  prefer the cheapest one. */
-    std::map<std::pair<std::vector<unsigned char>, int>, std::set<std::vector<unsigned char>, ShortestVectorFirstComparator>> scripts;
-    /** Merge other TaprootSpendData (for the same scriptPubKey) into this. */
-    void Merge(TaprootSpendData other);
-};
-
-/** Utility class to construct Taproot outputs from internal key and script tree. */
-class TaprootBuilder
-{
-private:
-    /** Information about a tracked leaf in the Merkle tree. */
-    struct LeafInfo
-    {
-        std::vector<unsigned char> script;   //!< The script.
-        int leaf_version;                    //!< The leaf version for that script.
-        std::vector<uint256> merkle_branch;  //!< The hashing partners above this leaf.
-    };
-
-    /** Information associated with a node in the Merkle tree. */
-    struct NodeInfo
-    {
-        /** Merkle hash of this node. */
-        uint256 hash;
-        /** Tracked leaves underneath this node (either from the node itself, or its children).
-         *  The merkle_branch field of each is the partners to get to *this* node. */
-        std::vector<LeafInfo> leaves;
-    };
-    /** Whether the builder is in a valid state so far. */
-    bool m_valid = true;
-
-    /** The current state of the builder.
-     *
-     * For each level in the tree, one NodeInfo object may be present. m_branch[0]
-     * is information about the root; further values are for deeper subtrees being
-     * explored.
-     *
-     * For every right branch taken to reach the position we're currently
-     * working in, there will be a (non-nullopt) entry in m_branch corresponding
-     * to the left branch at that level.
-     *
-     * For example, imagine this tree:     - N0 -
-     *                                    /      \
-     *                                   N1      N2
-     *                                  /  \    /  \
-     *                                 A    B  C   N3
-     *                                            /  \
-     *                                           D    E
-     *
-     * Initially, m_branch is empty. After processing leaf A, it would become
-     * {nullopt, nullopt, A}. When processing leaf B, an entry at level 2 already
-     * exists, and it would thus be combined with it to produce a level 1 one,
-     * resulting in {nullopt, N1}. Adding C and D takes us to {nullopt, N1, C}
-     * and {nullopt, N1, C, D} respectively. When E is processed, it is combined
-     * with D, and then C, and then N1, to produce the root, resulting in {N0}.
-     *
-     * This structure allows processing with just O(log n) overhead if the leaves
-     * are computed on the fly.
-     *
-     * As an invariant, there can never be nullopt entries at the end. There can
-     * also not be more than 128 entries (as that would mean more than 128 levels
-     * in the tree). The depth of newly added entries will always be at least
-     * equal to the current size of m_branch (otherwise it does not correspond
-     * to a depth-first traversal of a tree). m_branch is only empty if no entries
-     * have ever be processed. m_branch having length 1 corresponds to being done.
-     */
-    std::vector<std::optional<NodeInfo>> m_branch;
-
-    XOnlyPubKey m_internal_key;  //!< The internal key, set when finalizing.
-    XOnlyPubKey m_output_key;    //!< The output key, computed when finalizing.
-    bool m_parity;               //!< The tweak parity, computed when finalizing.
-
-    /** Combine information about a parent Merkle tree node from its child nodes. */
-    static NodeInfo Combine(NodeInfo&& a, NodeInfo&& b);
-    /** Insert information about a node at a certain depth, and propagate information up. */
-    void Insert(NodeInfo&& node, int depth);
-
-public:
-    /** Add a new script at a certain depth in the tree. Add() operations must be called
-     *  in depth-first traversal order of binary tree. If track is true, it will be included in
-     *  the GetSpendData() output. */
-    TaprootBuilder& Add(int depth, Span<const unsigned char> script, int leaf_version, bool track = true);
-    /** Like Add(), but for a Merkle node with a given hash to the tree. */
-    TaprootBuilder& AddOmitted(int depth, const uint256& hash);
-    /** Finalize the construction. Can only be called when IsComplete() is true.
-        internal_key.IsFullyValid() must be true. */
-    TaprootBuilder& Finalize(const XOnlyPubKey& internal_key);
-
-    /** Return true if so far all input was valid. */
-    bool IsValid() const { return m_valid; }
-    /** Return whether there were either no leaves, or the leaves form a Huffman tree. */
-    bool IsComplete() const { return m_valid && (m_branch.size() == 0 || (m_branch.size() == 1 && m_branch[0].has_value())); }
-    /** Compute scriptPubKey (after Finalize()). */
-    WitnessV1Taproot GetOutput();
-    /** Check if a list of depths is legal (will lead to IsComplete()). */
-    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, std::vector<unsigned char>>> GetTreeTuples() const;
-    /** Returns true if there are any tapscripts */
-    bool HasScripts() const { return !m_branch.empty(); }
-};
-
-/** Given a TaprootSpendData and the output key, reconstruct its script tree.
- *
- * If the output doesn't match the spenddata, or if the data in spenddata is incomplete,
- * std::nullopt is returned. Otherwise, a vector of (depth, script, leaf_ver) tuples is
- * returned, corresponding to a depth-first traversal of the script tree.
- */
-std::optional<std::vector<std::tuple<int, std::vector<unsigned char>, int>>> InferTaprootTree(const TaprootSpendData& spenddata, const XOnlyPubKey& output);
-
 #endif // BITCOIN_SCRIPT_STANDARD_H