feat: add Sapling node combinator

CHANGELOG.md

@@ -5,6 +5,12 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [0.7.5.0]
+
+### Added
+
+- Sapling commitment node functions
+
 ## [0.7.4.0]
 
 ### Added

librustzcash-wrapper/src/lib.rs

@@ -1561,6 +1561,47 @@ pub extern "C" fn rust_wrapper_read_sapling_node(
     }
 }
 
+#[no_mangle]
+pub extern "C" fn rust_wrapper_combine_sapling_nodes(
+    level: u8,
+    left: *const u8,
+    left_len: usize,
+    right: *const u8,
+    right_len: usize,
+    out: *mut u8,
+    out_len: &mut usize
+    ){
+    let left_in: Vec<u8> = marshall_from_haskell_var(left, left_len, RW);
+    let right_in: Vec<u8> = marshall_from_haskell_var(right, right_len, RW);
+    if left_in.len() == 1 {
+            let n = Node::combine(Level::new(level), &Node::empty_leaf(), &Node::empty_leaf());
+            let h = Hhex { bytes: n.to_bytes().to_vec() };
+            marshall_to_haskell_var(&h, out, out_len, RW);
+    } else {
+        let left_node = Node::from_bytes(to_array(left_in));
+        if left_node.is_some().into() {
+            if right_in.len() > 1 {
+                let right_node = Node::from_bytes(to_array(right_in));
+                if right_node.is_some().into() {
+                    let n = Node::combine(Level::new(level), &left_node.unwrap(), &right_node.unwrap());
+                    let h = Hhex { bytes: n.to_bytes().to_vec() };
+                    marshall_to_haskell_var(&h, out, out_len, RW);
+                } else {
+                    let h0 = Hhex { bytes: vec![0] };
+                    marshall_to_haskell_var(&h0, out, out_len, RW);
+                }
+            } else {
+                let n = Node::combine(Level::new(level), &left_node.unwrap(), &Node::empty_leaf());
+                let h = Hhex { bytes: n.to_bytes().to_vec() };
+                marshall_to_haskell_var(&h, out, out_len, RW);
+            }
+        } else {
+            let h0 = Hhex { bytes: vec![0] };
+            marshall_to_haskell_var(&h0, out, out_len, RW);
+        }
+    }
+}
+
 #[no_mangle]
 pub extern "C" fn rust_wrapper_read_orchard_frontier(
     tree: *const u8,

src/C/Zcash.chs

@@ -253,6 +253,15 @@ import ZcashHaskell.Types
   -> `()'
 #}
 
+{# fun unsafe rust_wrapper_combine_sapling_nodes as rustWrapperCombineSaplingNodes
+     { `Int8'
+     , toBorshVar* `BS.ByteString'&
+     , toBorshVar* `BS.ByteString'&
+     , getVarBuffer `Buffer HexString'&
+     }
+  -> `()'
+#}
+
 {# fun unsafe rust_wrapper_read_orchard_node as rustWrapperReadOrchardNode
      { toBorshVar* `BS.ByteString'&
      , getVarBuffer `Buffer HexString'&

src/ZcashHaskell/Sapling.hs

@@ -18,7 +18,8 @@
 module ZcashHaskell.Sapling where
 
 import C.Zcash
-  ( rustWrapperDecodeSaplingAddress
+  ( rustWrapperCombineSaplingNodes
+  , rustWrapperDecodeSaplingAddress
   , rustWrapperIsShielded
   , rustWrapperReadSaplingCommitmentTree
   , rustWrapperReadSaplingFrontier
@@ -39,6 +40,7 @@ import Data.Aeson
 import qualified Data.ByteString as BS
 import qualified Data.ByteString.Char8 as C
 import Data.HexString (HexString(..), fromText, hexString, toBytes, toText)
+import Data.Int (Int8)
 import qualified Data.Text as T
 import Data.Word
 import Foreign.Rust.Marshall.Variable
@@ -194,6 +196,16 @@ getSaplingNodeValue cmu =
   where
     n = withPureBorshVarBuffer $ rustWrapperReadSaplingNode cmu
 
+combineSaplingNodes :: Int8 -> HexString -> HexString -> Maybe HexString
+combineSaplingNodes level n1 n2 =
+  if BS.length (hexBytes r) > 1
+    then Just r
+    else Nothing
+  where
+    r =
+      withPureBorshVarBuffer $
+      rustWrapperCombineSaplingNodes level (toBytes n1) (toBytes n2)
+
 getSaplingFrontier :: SaplingCommitmentTree -> Maybe SaplingFrontier
 getSaplingFrontier tree =
   if sf_pos updatedTree > 1

zcash-haskell.cabal

@@ -5,7 +5,7 @@ cabal-version: 3.0
 -- see: https://github.com/sol/hpack
 
 name:           zcash-haskell
-version:        0.7.4.0
+version:        0.7.5.0
 synopsis:       Utilities to interact with the Zcash blockchain
 description:    Please see the README on the repo at <https://git.vergara.tech/Vergara_Tech/zcash-haskell#readme>
 category:       Blockchain