Create cached_tree_hash crate.

eth2/utils/cached_tree_hash/src/impls.rs

@@ -0,0 +1,70 @@
+use super::*;
+use crate::merkleize::merkleize;
+
+mod vec;
+
+impl CachedTreeHash<u64> for u64 {
+    fn new_tree_hash_cache(&self, _depth: usize) -> Result<TreeHashCache, Error> {
+        Ok(TreeHashCache::from_bytes(
+            merkleize(self.to_le_bytes().to_vec()),
+            false,
+            None,
+        )?)
+    }
+
+    fn num_tree_hash_cache_chunks(&self) -> usize {
+        1
+    }
+
+    fn tree_hash_cache_overlay(
+        &self,
+        _chunk_offset: usize,
+        _depth: usize,
+    ) -> Result<BTreeOverlay, Error> {
+        panic!("Basic should not produce overlay");
+        // BTreeOverlay::from_lengths(chunk_offset, 1, depth, vec![1])
+    }
+
+    fn update_tree_hash_cache(&self, cache: &mut TreeHashCache) -> Result<(), Error> {
+        let leaf = merkleize(self.to_le_bytes().to_vec());
+        cache.maybe_update_chunk(cache.chunk_index, &leaf)?;
+
+        cache.chunk_index += 1;
+        // cache.overlay_index += 1;
+
+        Ok(())
+    }
+}
+
+impl CachedTreeHash<usize> for usize {
+    fn new_tree_hash_cache(&self, _depth: usize) -> Result<TreeHashCache, Error> {
+        Ok(TreeHashCache::from_bytes(
+            merkleize(self.to_le_bytes().to_vec()),
+            false,
+            None,
+        )?)
+    }
+
+    fn num_tree_hash_cache_chunks(&self) -> usize {
+        1
+    }
+
+    fn tree_hash_cache_overlay(
+        &self,
+        _chunk_offset: usize,
+        _depth: usize,
+    ) -> Result<BTreeOverlay, Error> {
+        panic!("Basic should not produce overlay");
+        // BTreeOverlay::from_lengths(chunk_offset, 1, depth, vec![1])
+    }
+
+    fn update_tree_hash_cache(&self, cache: &mut TreeHashCache) -> Result<(), Error> {
+        let leaf = merkleize(self.to_le_bytes().to_vec());
+        cache.maybe_update_chunk(cache.chunk_index, &leaf)?;
+
+        cache.chunk_index += 1;
+        // cache.overlay_index += 1;
+
+        Ok(())
+    }
+}