Merge pull request #1149 from maraoz/lazy/xpubkey

lazy calc for xpubkey in HDPrivateKey

lib/hdprivatekey.js

@@ -365,6 +365,15 @@ HDPrivateKey.fromSeed = function(hexa, network) {
   });
 };
 
+
+
+HDPrivateKey.prototype._calcHDPublicKey = function() {
+  if (!this._hdPublicKey) {
+    var HDPublicKey = require('./hdpublickey');
+    this._hdPublicKey = new HDPublicKey(this);
+  }
+};
+
 /**
  * Receives a object with buffers in all the properties and populates the
  * internal structure
@@ -423,14 +432,24 @@ HDPrivateKey.prototype._buildFromBuffers = function(arg) {
     fingerPrint: fingerPrint
   });
 
-  var HDPublicKey = require('./hdpublickey');
-  var hdPublicKey = new HDPublicKey(this);
+  this._hdPublicKey = null;
 
-  JSUtil.defineImmutable(this, {
-    hdPublicKey: hdPublicKey,
-    xpubkey: hdPublicKey.xpubkey
+  Object.defineProperty(this, 'hdPublicKey', {
+    configurable: false,
+    enumerable: true,
+    get: function() {
+      this._calcHDPublicKey();
+      return this._hdPublicKey;
+    }
+  });
+  Object.defineProperty(this, 'xpubkey', {
+    configurable: false,
+    enumerable: true,
+    get: function() {
+      this._calcHDPublicKey();
+      return this._hdPublicKey.xpubkey;
+    }
   });
-
   return this;
 };
 

test/hdprivatekey.js

@@ -100,6 +100,14 @@ describe('HDPrivate key interface', function() {
       testnetKey.publicKey.network.should.equal(Networks.testnet);
       livenetKey.publicKey.network.should.equal(Networks.livenet);
     });
+
+    it('cache for xpubkey works', function() {
+      var privateKey = new HDPrivateKey(xprivkey);
+      should.not.exist(privateKey._hdPublicKey);
+      privateKey.xpubkey.should.equal(privateKey.xpubkey);
+      should.exist(privateKey._hdPublicKey);
+    });
+
   });
 
   it('inspect() displays correctly', function() {