feat: export HashSizes for the different TrieHasher hashers via the T…

…rieSpec

hasher.go

@@ -29,6 +29,8 @@ type PathHasher interface {
 type ValueHasher interface {
 	// HashValue hashes value data to produce the digest stored in leaf node.
 	HashValue([]byte) []byte
+	// ValueHashSize returns the length (in bytes) of digests produced by this hasher.
+	ValueHashSize() int
 }
 
 type trieHasher struct {
@@ -59,10 +61,19 @@ func (ph *pathHasher) PathSize() int {
 	return ph.hasher.Size()
 }
 
+// HashValue hashes the producdes a digest of the data provided by the value hasher
 func (vh *valueHasher) HashValue(data []byte) []byte {
 	return vh.digest(data)
 }
 
+// ValueHashSize returns the length (in bytes) of digests produced by the value hasher
+func (vh *valueHasher) ValueHashSize() int {
+	if vh.hasher == nil {
+		return 0
+	}
+	return vh.hasher.Size()
+}
+
 func (th *trieHasher) digest(data []byte) []byte {
 	th.hasher.Write(data)
 	sum := th.hasher.Sum(nil)

types.go

@@ -98,6 +98,18 @@ func newTrieSpec(hasher hash.Hash, sumTrie bool) TrieSpec {
 // Spec returns the TrieSpec associated with the given trie
 func (spec *TrieSpec) Spec() *TrieSpec { return spec }
 
+// PathHasherSize returns the length (in bytes) of digests produced by the
+// path hasher
+func (spec *TrieSpec) PathHasherSize() int { return spec.ph.PathSize() }
+
+// ValueHasherSize returns the length (in bytes) of digests produced by the
+// value hasher
+func (spec *TrieSpec) ValueHasherSize() int { return spec.vh.ValueHashSize() }
+
+// TrieHasherSize returns the length (in bytes) of digests produced by the
+// trie hasher
+func (spec *TrieSpec) TrieHasherSize() int { return spec.th.hashSize() }
+
 func (spec *TrieSpec) depth() int { return spec.ph.PathSize() * 8 }
 func (spec *TrieSpec) digestValue(data []byte) []byte {
 	if spec.vh == nil {