Implemented undo/redo

sources/scripts/lib/history.js

@@ -0,0 +1,40 @@
+function History()
+{
+  this.index = 0;
+  this.a = [];
+
+  this.push = function(data)
+  {
+    if(this.index < this.a.length-1){
+      this.fork();
+    }
+    this.index = this.a.length;
+    this.a = this.a.slice(0,this.index);
+    this.a.push(copy(data));
+  }
+
+  this.fork = function()
+  {
+    this.a = this.a.slice(0,this.index+1);
+  }
+
+  this.pop = function()
+  {
+    return this.a.pop();
+  }
+
+  this.prev = function()
+  {
+    this.index = clamp(this.index-1,0,this.a.length-1);
+    return copy(this.a[this.index]);
+  }
+
+  this.next = function()
+  {
+    this.index = clamp(this.index+1,0,this.a.length-1);
+    return copy(this.a[this.index]);
+  }
+
+  function copy(data){ return data.slice(0); }
+  function clamp(v, min, max) { return v < min ? min : v > max ? max : v; }
+}