[WIP] Sparse Merkle Tree Generic Key Size

CHANGELOG.md

@@ -200,6 +200,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 #### Changed
 
+- [#660](https://github.com/FuelLabs/fuel-vm/pull/660): Added generic argument to the sparse Merkle tree to allow users to define the key space. The default export sparse Merkle tree is defined as the 32 byte SMT to ensure compatability. 
 - [#653](https://github.com/FuelLabs/fuel-vm/pull/653): `ECAL` opcode handler can now hold internal state.
 - [#657](https://github.com/FuelLabs/fuel-vm/pull/657): Add debugger methods to remove or replace all breakpoints at
   once.

fuel-merkle/Cargo.toml

@@ -16,6 +16,7 @@ digest = { version = "0.10", default-features = false }
 fuel-storage = { workspace = true, default-features = false }
 hashbrown = "0.13"
 hex = { version = "0.4", default-features = false, features = ["alloc"] }
+once_cell = { version = "1.19", default-features = false, features = ["race"] }
 serde = { version = "1.0", default-features = false, optional = true }
 sha2 = { version = "0.10", default-features = false }
 

fuel-merkle/src/common.rs

@@ -27,6 +27,7 @@ pub type Bytes4 = [u8; 4];
 pub type Bytes8 = [u8; 8];
 pub type Bytes16 = [u8; 16];
 pub type Bytes32 = [u8; 32];
+pub type Bytes<const N: usize> = [u8; N];
 
 use alloc::vec::Vec;
 pub type ProofSet = Vec<Bytes32>;

fuel-merkle/src/common/node.rs

@@ -1,7 +1,4 @@
-use crate::common::{
-    Bytes32,
-    Bytes8,
-};
+use crate::common::Bytes;
 
 use alloc::string::String;
 use core::fmt;
@@ -56,15 +53,23 @@ where
     }
 }
 
-impl KeyFormatting for Bytes8 {
-    type PrettyType = u64;
+// impl KeyFormatting for Bytes8 {
+//     type PrettyType = u64;
+//
+//     fn pretty(&self) -> Self::PrettyType {
+//         u64::from_be_bytes(*self)
+//     }
+// }
+//
+// impl KeyFormatting for Bytes32 {
+//     type PrettyType = String;
+//
+//     fn pretty(&self) -> Self::PrettyType {
+//         hex::encode(self)
+//     }
+// }
 
-    fn pretty(&self) -> Self::PrettyType {
-        u64::from_be_bytes(*self)
-    }
-}
-
-impl KeyFormatting for Bytes32 {
+impl<const N: usize> KeyFormatting for Bytes<N> {
     type PrettyType = String;
 
     fn pretty(&self) -> Self::PrettyType {

fuel-merkle/src/sparse/generic.rs

@@ -0,0 +1,13 @@
+pub mod branch;
+pub mod hash;
+pub mod merkle_tree;
+pub mod node;
+pub mod primitive;
+
+pub use merkle_tree::{
+    MerkleTree,
+    MerkleTreeError,
+    MerkleTreeKey,
+};
+pub(crate) use node::Node;
+pub(crate) use primitive::Primitive;

fuel-merkle/src/sparse/generic/hash.rs

@@ -0,0 +1,29 @@
+use crate::common::Bytes;
+use alloc::{
+    vec,
+    vec::Vec,
+};
+use once_cell::race::OnceBox;
+
+use digest::Digest;
+use sha2::Sha256 as Hash;
+
+pub fn zero_sum<const N: usize>() -> &'static [u8; N] {
+    static ZERO: OnceBox<Vec<u8>> = OnceBox::new();
+    ZERO.get_or_init(|| Box::new(vec![0; N]))
+        .as_slice()
+        .try_into()
+        .expect("Expected valid zero sum")
+}
+
+pub fn sum<I, const N: usize>(data: I) -> Bytes<N>
+where
+    I: AsRef<[u8]>,
+{
+    let mut hash = Hash::new();
+    hash.update(data);
+    let hash = hash.finalize();
+    let mut vec = hash.as_slice().to_vec();
+    vec.truncate(N);
+    vec.try_into().unwrap()
+}