From fa07601a2a5f040434295677501c7f30309d3d0f Mon Sep 17 00:00:00 2001
From: Stefan Thomas <justmoon@members.fsf.org>
Date: Sat, 25 Jan 2014 11:30:58 -0800
Subject: [PATCH] UInt: Add UInt#_update for creating subclasses that have
 dependent state.

---
 src/js/ripple/uint.js    | 30 ++++++++++++++++++++++++++++++
 src/js/ripple/uint160.js |  6 ++++++
 2 files changed, 36 insertions(+)

diff --git a/src/js/ripple/uint.js b/src/js/ripple/uint.js
index 545d517b..4f2338be 100644
--- a/src/js/ripple/uint.js
+++ b/src/js/ripple/uint.js
@@ -15,6 +15,8 @@ var Base = require('./base').Base;
 var UInt = function () {
   // Internal form: NaN or BigInteger
   this._value  = NaN;
+
+  this._update();
 };
 
 UInt.json_rewrite = function (j, opts) {
@@ -96,6 +98,8 @@ UInt.prototype.clone = function () {
 UInt.prototype.copyTo = function (d) {
   d._value = this._value;
 
+  if ("function" === typeof d._update) d._update();
+
   return d;
 };
 
@@ -111,6 +115,20 @@ UInt.prototype.is_zero = function () {
   return this._value.equals(BigInteger.ZERO);
 };
 
+/**
+ * Update any derivative values.
+ *
+ * This allows subclasses to maintain caches of any data that they derive from
+ * the main _value. For example, the Currency class keeps the currency type, the
+ * currency code and other information about the currency cached.
+ *
+ * The reason for keeping this mechanism in this class is so every subclass can
+ * call it whenever it modifies the internal state.
+ */
+UInt.prototype._update = function () {
+  // Nothing to do by default. Subclasses will override this.
+};
+
 // value = NaN on error.
 UInt.prototype.parse_generic = function (j) {
   // Canonicalize and validate
@@ -150,6 +168,8 @@ UInt.prototype.parse_generic = function (j) {
     }
   }
 
+  this._update();
+
   return this;
 };
 
@@ -161,6 +181,8 @@ UInt.prototype.parse_hex = function (j) {
     this._value  = NaN;
   }
 
+  this._update();
+
   return this;
 };
 
@@ -172,6 +194,8 @@ UInt.prototype.parse_bits = function (j) {
     this.parse_bytes(bytes);
   }
 
+  this._update();
+
   return this;
 };
 
@@ -183,6 +207,8 @@ UInt.prototype.parse_bytes = function (j) {
 	  this._value  = new BigInteger([0].concat(j), 256);
   }
 
+  this._update();
+
   return this;
 };
 
@@ -198,6 +224,8 @@ UInt.prototype.parse_bn = function (j) {
     this._value = NaN;
   }
 
+  this._update();
+
   return this;
 };
 
@@ -211,6 +239,8 @@ UInt.prototype.parse_number = function (j) {
     this._value = new BigInteger(""+j);
   }
 
+  this._update();
+
   return this;
 };
 
diff --git a/src/js/ripple/uint160.js b/src/js/ripple/uint160.js
index 8b405959..55fc4d0d 100644
--- a/src/js/ripple/uint160.js
+++ b/src/js/ripple/uint160.js
@@ -16,6 +16,8 @@ var UInt160 = extend(function () {
   // Internal form: NaN or BigInteger
   this._value  = NaN;
   this._version_byte = void(0);
+
+  this._update();
 }, UInt);
 
 UInt160.width = 20;
@@ -61,6 +63,8 @@ UInt160.prototype.parse_json = function (j) {
     this.parse_hex(j);
   }
 
+  this._update();
+
   return this;
 };
 
@@ -73,6 +77,8 @@ UInt160.prototype.parse_generic = function (j) {
     }
   }
 
+  this._update();
+
   return this;
 };