Add descriptor expansion cache

1 files changed, 11 insertions, 1 deletions

diff --git a/src/script/descriptor.h b/src/script/descriptor.h
index 0111972f85..44f0efca03 100644
--- a/src/script/descriptor.h
+++ b/src/script/descriptor.h
@@ -48,8 +48,18 @@ struct Descriptor {
      * provider: the provider to query for private keys in case of hardened derivation.
      * output_script: the expanded scriptPubKeys will be put here.
      * out: scripts and public keys necessary for solving the expanded scriptPubKeys will be put here (may be equal to provider).
+     * cache: vector which will be overwritten with cache data necessary to-evaluate the descriptor at this point without access to private keys.
      */
-    virtual bool Expand(int pos, const SigningProvider& provider, std::vector<CScript>& output_scripts, FlatSigningProvider& out) const = 0;
+    virtual bool Expand(int pos, const SigningProvider& provider, std::vector<CScript>& output_scripts, FlatSigningProvider& out, std::vector<unsigned char>* cache = nullptr) const = 0;
+
+    /** Expand a descriptor at a specified position using cached expansion data.
+     *
+     * pos: the position at which to expand the descriptor. If IsRange() is false, this is ignored.
+     * cache: vector from which cached expansion data will be read.
+     * output_script: the expanded scriptPubKeys will be put here.
+     * out: scripts and public keys necessary for solving the expanded scriptPubKeys will be put here (may be equal to provider).
+     */
+    virtual bool ExpandFromCache(int pos, const std::vector<unsigned char>& cache, std::vector<CScript>& output_scripts, FlatSigningProvider& out) const = 0;
 };
 
 /** Parse a descriptor string. Included private keys are put in out. Returns nullptr if parsing fails. */