Remove num_bytes method

eth2/utils/tree_hash/src/impls.rs

@@ -18,16 +18,12 @@ impl CachedTreeHash<u64> for u64 {
         BTreeOverlay::from_lengths(chunk_offset, vec![1])
     }
 
-    fn num_bytes(&self) -> usize {
-        8
-    }
-
     fn packed_encoding(&self) -> Result<Vec<u8>, Error> {
         Ok(ssz_encode(self))
     }
 
     fn packing_factor() -> usize {
-        32 / 8
+        HASHSIZE / 8
     }
 
     fn cached_hash_tree_root(
@@ -86,10 +82,6 @@ where
         BTreeOverlay::from_lengths(chunk_offset, lengths)
     }
 
-    fn num_bytes(&self) -> usize {
-        self.iter().fold(0, |acc, item| acc + item.num_bytes())
-    }
-
     fn packed_encoding(&self) -> Result<Vec<u8>, Error> {
         Err(Error::ShouldNeverBePacked(Self::item_type()))
     }
@@ -219,7 +211,7 @@ fn get_packed_leaves<T>(vec: &Vec<T>) -> Result<Vec<u8>, Error>
 where
     T: CachedTreeHash<T>,
 {
-    let num_packed_bytes = vec.num_bytes();
+    let num_packed_bytes = (BYTES_PER_CHUNK / T::packing_factor()) * vec.len();
     let num_leaves = num_sanitized_leaves(num_packed_bytes);
 
     let mut packed = Vec::with_capacity(num_leaves * HASHSIZE);

eth2/utils/tree_hash/src/lib.rs

@@ -42,10 +42,6 @@ pub trait CachedTreeHash<Item>: Debug {
 
     fn build_tree_hash_cache(&self) -> Result<TreeHashCache, Error>;
 
-    /// Return the number of bytes when this element is encoded as raw SSZ _without_ length
-    /// prefixes.
-    fn num_bytes(&self) -> usize;
-
     fn btree_overlay(&self, chunk_offset: usize) -> Result<BTreeOverlay, Error>;
 
     fn packed_encoding(&self) -> Result<Vec<u8>, Error>;

eth2/utils/tree_hash/tests/tests.rs

@@ -33,17 +33,6 @@ impl CachedTreeHash<Inner> for Inner {
         Ok(tree)
     }
 
-    fn num_bytes(&self) -> usize {
-        let mut bytes = 0;
-
-        bytes += self.a.num_bytes();
-        bytes += self.b.num_bytes();
-        bytes += self.c.num_bytes();
-        bytes += self.d.num_bytes();
-
-        bytes
-    }
-
     fn btree_overlay(&self, chunk_offset: usize) -> Result<BTreeOverlay, Error> {
         let mut lengths = vec![];
 
@@ -115,14 +104,6 @@ impl CachedTreeHash<Outer> for Outer {
         Ok(tree)
     }
 
-    fn num_bytes(&self) -> usize {
-        let mut bytes = 0;
-        bytes += self.a.num_bytes();
-        bytes += self.b.num_bytes();
-        bytes += self.c.num_bytes();
-        bytes
-    }
-
     fn btree_overlay(&self, chunk_offset: usize) -> Result<BTreeOverlay, Error> {
         let mut lengths = vec![];