allow re-binding by internally cloning before re-use

CHANGELOG.md

@@ -1,6 +1,10 @@
 # Changelog
 
 
+### 1.2.1 (2016-07-10)
+- Fix: allow re-use of bindings again, by internally cloning binding before re-use.
+
+
 ### 1.2.0 (2016-07-10)
 - Feature: shorthand for binding to parent node is now just defining a change function or definition object, no CSS selector string or DOM Node required.
 

README.md

@@ -117,7 +117,7 @@ var node = simulacra(data, bindings)
 var initialData = clone(data)
 
 // Do some mutations, and then reset to initial state.
-node = simulacra(initialData, clone(bindings))
+node = simulacra(initialData, bindings)
 ```
 
 This is just one way to implement time travel, but not the most efficient.

lib/index.js

@@ -52,8 +52,9 @@ function simulacra (obj, def) {
   if (!isArray(def))
     throw new TypeError('Second argument must be an array.')
 
-  if (isProcessedKey in def)
-    throw new Error('Can not re-use binding.')
+  // Need to clone bindings before re-using them, due to the marker mappings
+  // being coupled to the definitions.
+  if (isProcessedKey in def) def = clone(def)
 
   if (typeof def[0] === 'string') {
     query = def[0]
@@ -240,3 +241,30 @@ function featureCheck (globalScope) {
     }
   }
 }
+
+
+/**
+ * A fast deep clone function, which should work for the use case of cloning
+ * bindings before re-use.
+ *
+ * @param {*}
+ * @return {*}
+ */
+function clone (input) {
+  var output, key, value, isArray
+
+  if (Array.isArray(input)) isArray = true
+  else if (input == null || Object.getPrototypeOf(input) !== Object.prototype)
+    return input
+
+  output = isArray ? [] : {}
+
+  for (key in input) {
+    value = input[key]
+    output[key] = value != null &&
+      Object.getPrototypeOf(value) === Object.prototype ||
+      Array.isArray(value) ? clone(value) : value
+  }
+
+  return output
+}

package.json

@@ -1,7 +1,7 @@
 {
   "name": "simulacra",
   "description": "One-way data binding for web applications.",
-  "version": "1.2.0",
+  "version": "1.2.1",
   "license": "MIT",
   "author": {
     "email": "0x8890@airmail.cc",

test/index.js

@@ -3,8 +3,6 @@
 var tapdance = require('tapdance')
 var comment = tapdance.comment
 var ok = tapdance.ok
-var pass = tapdance.pass
-var fail = tapdance.fail
 var run = tapdance.run
 
 var simulacra = require('../lib')
@@ -35,6 +33,7 @@ run(function () {
 
 run(function () {
   var template, fragment, data, bindings, outlet, i = 0
+  var isRebinding = false
 
   comment('test main use case')
 
@@ -61,8 +60,11 @@ run(function () {
   bindings = [ fragment, {
     name: [ '.name', function (node, value, previousValue, path) {
       ok(path.length === 1, 'path length is correct')
-      ok(path.root === data, 'root is correct')
-      ok(path.target === data, 'target is correct')
+      if (!isRebinding) {
+        isRebinding = true
+        ok(path.root === data, 'root is correct')
+        ok(path.target === data, 'target is correct')
+      }
       ok(path[0] === 'name', 'path is correct')
       return value + '!'
     } ],
@@ -127,14 +129,12 @@ run(function () {
   ok(outlet.querySelector('.size').textContent === 'XXL',
     'continues to work after error')
 
-  comment('rebinding should fail')
-  try {
-    simulacra({}, bindings)
-    fail('should have failed')
-  }
-  catch (error) {
-    pass('rebinding does not work')
-  }
+  comment('test rebinding')
+  outlet.innerHTML = ''
+  outlet.appendChild(simulacra({
+    name: 'babby'
+  }, bindings))
+  ok(outlet.textContent === 'babby!', 'rebinding works')
 })