From 96e254a46b3cf8507ad746c6ce4ddfdd62bacaaa Mon Sep 17 00:00:00 2001
From: poma <semenov.roma@gmail.com>
Date: Wed, 23 Sep 2020 19:22:14 +0300
Subject: [PATCH] serialization

---
 package.json            |  2 +-
 src/merkleTree.js       | 30 ++++++++++++++++++++++++++++++
 test/merkleTree.test.js | 15 +++++++++++++++
 3 files changed, 46 insertions(+), 1 deletion(-)

diff --git a/package.json b/package.json
index 39e769b..bc6065a 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "fixed-merkle-tree",
-  "version": "0.3.4",
+  "version": "0.4.0",
   "description": "Fixed depth merkle tree implementation with sequential inserts",
   "main": "src/merkleTree.js",
   "scripts": {
diff --git a/src/merkleTree.js b/src/merkleTree.js
index ba68d17..4fc6b92 100644
--- a/src/merkleTree.js
+++ b/src/merkleTree.js
@@ -152,6 +152,36 @@ class MerkleTree {
   elements() {
     return this._layers[0].slice()
   }
+
+  /**
+   * Serialize entire tree state including intermediate layers into a plain object
+   * Deserializing it back will not require to recompute any hashes
+   * Elements are not converted to a plain type, this is responsibility of the caller
+   */
+  serialize() {
+    return {
+      levels: this.levels,
+      capacity: this.capacity,
+      zeroElement: this.zeroElement,
+      _zeros: this._zeros,
+      _layers: this._layers,
+    }
+  }
+
+  /**
+   * Deserialize data into a MerkleTree instance
+   * Make sure to provide the same hashFunction as was used in the source tree,
+   * otherwise the tree state will be invalid
+   *
+   * @param data
+   * @param hashFunction
+   * @returns {MerkleTree}
+   */
+  static deserialize(data, hashFunction) {
+    const instance = Object.assign(Object.create(this.prototype), data)
+    instance._hash = hashFunction || defaultHash
+    return instance
+  }
 }
 
 module.exports = MerkleTree
diff --git a/test/merkleTree.test.js b/test/merkleTree.test.js
index 29e69b9..b941abc 100644
--- a/test/merkleTree.test.js
+++ b/test/merkleTree.test.js
@@ -202,4 +202,19 @@ describe('MerkleTree', () => {
       ])
     })
   })
+
+  describe('#serialize', () => {
+    it('should work', () => {
+      const src = new MerkleTree(10, [1, 2, 3])
+      const data = src.serialize()
+      const dst = MerkleTree.deserialize(data)
+
+      src.root().should.equal(dst.root())
+
+      src.insert(10)
+      dst.insert(10)
+
+      src.root().should.equal(dst.root())
+    })
+  })
 })