feat(MerkleTree): add MerkleTree class

lib/merkleTree.js

@@ -0,0 +1,69 @@
+var bitcore = require('bitcore')
+var hash = bitcore.crypto.Hash.sha256sha256
+
+var MerkleTree = module.exports = function () {
+  this.depth = 0
+  this._root = null
+  this.txids = []
+  this.matched = []
+}
+
+MerkleTree.fromMerkleBlock = function (block) {
+  var tree = new MerkleTree()
+  var hashes = block.hashes
+  var flags = block.flags
+
+  tree.depth = Math.ceil(Math.log(block.numTransactions) / Math.log(2))
+  var stack = []
+
+  for (var i = 0; i < flags.length; i++) {
+    var flag = flags[i]
+    var node
+    var depth = stack.length
+    var leaf = depth === tree.depth
+    var cursor = stack[stack.length - 1]
+
+    if (leaf) {
+      node = new Node(hashes.shift())
+      tree.txids.push(hash)
+      if (flag) tree.matched.push(hash)
+    } else {
+      node = new Node(flag ? null : hashes.shift())
+
+      if (cursor) {
+        var left = cursor.add(node)
+        if (!left && !flag) cursor = stack.pop()
+      }
+
+      if (flag) stack.push(node)
+    }
+
+    if (!i) tree._root = node
+  }
+
+  return tree
+}
+
+MerkleTree.prototype.root = function () {
+  return this._root.getHash()
+}
+
+var Node = function (hash) {
+  this.hash = hash
+  this.left = null
+  this.right = null
+}
+MerkleTree.Node = Node
+
+Node.prototype.getHash = function () {
+  if (this.hash) return this.hash
+  var leftHash = this.left.getHash()
+  var rightHash = (this.right || this.left).getHash()
+  return hash(leftHash.concat(rightHash))
+}
+
+Node.prototype.add = function (child) {
+  var left = !this.left
+  this[left ? 'left' : 'right'] = child
+  return left
+}