Begin implementing cached hashing in types

eth2/utils/cached_tree_hash/src/lib.rs

@@ -1,4 +1,5 @@
 use hashing::hash;
+use merkleize::num_unsanitized_leaves;
 use std::ops::Range;
 use tree_hash::{TreeHash, TreeHashType, BYTES_PER_CHUNK, HASHSIZE};
 
@@ -62,3 +63,92 @@ impl CachedTreeHasher {
         Ok(self.cache.root()?.to_vec())
     }
 }
+
+#[macro_export]
+macro_rules! cached_tree_hash_ssz_encoding_as_vector {
+    ($type: ident, $num_bytes: expr) => {
+        impl cached_tree_hash::CachedTreeHash<$type> for $type {
+            fn new_tree_hash_cache(
+                &self,
+                depth: usize,
+            ) -> Result<cached_tree_hash::TreeHashCache, cached_tree_hash::Error> {
+                let (cache, _schema) = cached_tree_hash::impls::vec::new_tree_hash_cache(
+                    &ssz::ssz_encode(self),
+                    depth,
+                )?;
+
+                Ok(cache)
+            }
+
+            fn tree_hash_cache_schema(&self, depth: usize) -> cached_tree_hash::BTreeSchema {
+                let lengths =
+                    vec![1; cached_tree_hash::merkleize::num_unsanitized_leaves($num_bytes)];
+                cached_tree_hash::BTreeSchema::from_lengths(depth, lengths)
+            }
+
+            fn update_tree_hash_cache(
+                &self,
+                cache: &mut cached_tree_hash::TreeHashCache,
+            ) -> Result<(), cached_tree_hash::Error> {
+                cached_tree_hash::impls::vec::update_tree_hash_cache(
+                    &ssz::ssz_encode(self),
+                    cache,
+                )?;
+
+                Ok(())
+            }
+        }
+    };
+}
+
+#[macro_export]
+macro_rules! cached_tree_hash_bytes_as_list {
+    ($type: ident) => {
+        impl cached_tree_hash::CachedTreeHash<$type> for $type {
+            fn new_tree_hash_cache(
+                &self,
+                depth: usize,
+            ) -> Result<cached_tree_hash::TreeHashCache, cached_tree_hash::Error> {
+                let bytes = self.to_bytes();
+
+                let (mut cache, schema) =
+                    cached_tree_hash::impls::vec::new_tree_hash_cache(&bytes, depth)?;
+
+                cache.add_length_nodes(schema.into_overlay(0).chunk_range(), bytes.len())?;
+
+                Ok(cache)
+            }
+
+            fn num_tree_hash_cache_chunks(&self) -> usize {
+                // Add two extra nodes to cater for the node before and after to allow mixing-in length.
+                cached_tree_hash::BTreeOverlay::new(self, 0, 0).num_chunks() + 2
+            }
+
+            fn tree_hash_cache_schema(&self, depth: usize) -> cached_tree_hash::BTreeSchema {
+                cached_tree_hash::impls::vec::produce_schema(&ssz::ssz_encode(self), depth)
+            }
+
+            fn update_tree_hash_cache(
+                &self,
+                cache: &mut cached_tree_hash::TreeHashCache,
+            ) -> Result<(), cached_tree_hash::Error> {
+                let bytes = self.to_bytes();
+
+                // Skip the length-mixed-in root node.
+                cache.chunk_index += 1;
+
+                // Update the cache, returning the new overlay.
+                let new_overlay =
+                    cached_tree_hash::impls::vec::update_tree_hash_cache(&bytes, cache)?;
+
+                // Mix in length
+                cache.mix_in_length(new_overlay.chunk_range(), bytes.len())?;
+
+                // Skip an extra node to clear the length node.
+                cache.chunk_index = new_overlay.next_node() + 1;
+
+                Ok(())
+            }
+        }
+    };
+}