stream: give access to tree aspects

stream.go

@@ -9,7 +9,7 @@ import (
 // NewHash provides a hash.Hash to generate a merkle.Tree checksum, given a
 // HashMaker for the checksums of the blocks written and the blockSize of each
 // block per node in the tree.
-func NewHash(hm HashMaker, merkleBlockLength int) hash.Hash {
+func NewHash(hm HashMaker, merkleBlockLength int) HashTreeer {
 	mh := new(merkleHash)
 	mh.blockSize = merkleBlockLength
 	mh.hm = hm
@@ -18,6 +18,19 @@ func NewHash(hm HashMaker, merkleBlockLength int) hash.Hash {
 	return mh
 }
 
+// Treeer (Tree-er) provides access to the Merkle tree internals
+type Treeer interface {
+	Nodes() []*Node
+	Root() *Node
+}
+
+// HashTreeer can be used as a hash.Hash but also provide access to the Merkle
+// tree internals
+type HashTreeer interface {
+	hash.Hash
+	Treeer
+}
+
 // TODO make a similar hash.Hash, that accepts an argument of a merkle.Tree,
 // that will validate nodes as the new bytes are written. If a new written
 // block fails checksum, then return an error on the io.Writer
@@ -31,6 +44,14 @@ type merkleHash struct {
 	partialLastNode bool // true when Sum() has appended a Node for a partial block
 }
 
+func (mh merkleHash) Nodes() []*Node {
+	return mh.tree.Nodes
+}
+
+func (mh merkleHash) Root() *Node {
+	return mh.tree.Root()
+}
+
 // XXX this will be tricky, as the last block can be less than the BlockSize.
 // if they get the sum, it will be mh.tree.Root().Checksum() at that point.
 //