[WIP] Rehydration

packages/dom-helper/lib/main.js

@@ -550,6 +550,47 @@ prototype.parseHTML = function(html, contextualElement) {
   return fragment;
 };
 
+const SHOW_TEXT = 4;
+
+prototype.preserveTextNodes = function(root) {
+  let iterator = this.document.createNodeIterator(root, SHOW_TEXT, function(node) {
+    return node.nodeValue === '' || (node.previousSibling && node.previousSibling.nodeType === 3);
+  });
+
+  let node;
+
+  /*jshint boss:true*/
+  while (node = iterator.nextNode()) {
+    let element = this.createElement('script');
+
+    if (node.nodeValue === '') {
+      this.setAttribute(element, 'data-hbs', 'boundary');
+      node.parentNode.replaceChild(element, node);
+    } else {
+      this.setAttribute(element, 'data-hbs', 'separator');
+      node.parentNode.insertBefore(element, node);
+    }
+  }
+};
+
+prototype.restoreTextNodes = function(root) {
+  let elements = root.querySelectorAll('script[data-hbs]');
+
+  for (let i=0, l=elements.length; i<l; i++) {
+    let element = elements[i];
+
+    switch (this.getAttribute(element, 'data-hbs')) {
+      case 'boundary':
+        element.parentNode.replaceChild(this.createTextNode(''), element);
+        break;
+
+      case 'separator':
+        element.parentNode.removeChild(element);
+        break;
+    }
+  }
+};
+
 var parsingNode;
 
 // Used to determine whether a URL needs to be sanitized.

packages/htmlbars-compiler/lib/template-compiler.js

@@ -3,7 +3,7 @@ import FragmentJavaScriptCompiler from './fragment-javascript-compiler';
 import HydrationOpcodeCompiler from './hydration-opcode-compiler';
 import HydrationJavaScriptCompiler from './hydration-javascript-compiler';
 import TemplateVisitor from "./template-visitor";
-import { processOpcodes } from "./utils";
+import { processOpcodes, generateId } from "./utils";
 import { repeat } from "../htmlbars-util/quoting";
 import { map } from "../htmlbars-util/array-utils";
 
@@ -110,6 +110,7 @@ TemplateCompiler.prototype.endProgram = function(program, programDepth) {
     indent+'  return {\n' +
     this.buildMeta(indent+'    ', program) +
     indent+'    isEmpty: ' + (program.body.length ? 'false' : 'true') + ',\n' +
+    indent+'    id: "' + generateId() + '",\n' +
     indent+'    arity: ' + blockParams.length + ',\n' +
     indent+'    cachedFragment: null,\n' +
     indent+'    hasRendered: false,\n' +

packages/htmlbars-compiler/lib/utils.js

@@ -1,3 +1,6 @@
+/*globals window:false*/
+/*globals Uint8Array:false*/
+
 export function processOpcodes(compiler, opcodes) {
   for (var i=0, l=opcodes.length; i<l; i++) {
     var method = opcodes[i][0];
@@ -9,3 +12,30 @@ export function processOpcodes(compiler, opcodes) {
     }
   }
 }
+
+let lookup = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/';
+var generateId;
+
+if (typeof window !== 'undefined' && window.crypto) {
+  generateId = function() {
+    let buf = new Uint8Array(12);
+    window.crypto.getRandomValues(buf);
+
+    buf = buf.map(i => i % 64);
+    return [].slice.call(buf).map(i => lookup.charAt(i)).join('');
+  };
+} else {
+  generateId = function() {
+    let buf = [];
+
+    for (let i=0; i<12; i++) {
+      buf.push(lookup.charAt(Math.floor(Math.random() * 64)));
+    }
+
+    return buf.join('');
+  };
+}
+
+// generateId() returns a unique 12-character string consisting of random
+// base64 characters.
+export { generateId };

packages/htmlbars-compiler/tests/compile-tests.js

@@ -47,3 +47,15 @@ test('options are not required for `compile`', function () {
 
   ok(template.meta, 'meta is present in template, even if empty');
 });
+
+test('templates get unique ids', function() {
+  var template1 = compile('{{#if foo}}hello{{/if}}');
+
+  ok(typeof template1.raw.id === 'string', 'the top-level template has an id');
+  ok(typeof template1.raw.templates[0].id === 'string', 'nested templates have ids');
+
+  var template2 = compile('Another template');
+  ok(typeof template2.raw.id === 'string', 'the top-level template has an id');
+
+  notEqual(template1.raw.id, template2.raw.id, 'different templates should have different ids');
+});