refactor($compile): Create non-descriptive comments when debugInfoEnabled is false

When debugInfoEnabled is `false` when comments generated by transclusions, ngIf,
ngRepeat and ngSwitch will not contain any information about the directive nor
the expression associated with it.

Closes: #8722

Author: lgalfaso

src/ng/compile.js

@@ -1508,6 +1508,14 @@ function $CompileProvider($provide, $$sanitizeUriProvider) {
       safeAddClass($element, isolated ? 'ng-isolate-scope' : 'ng-scope');
     } : noop;
 
+    compile.$createComment = function(directiveName, comment) {
+      var content = '';
+      if (debugInfoEnabled) {
+        content = ' ' + (directiveName || '') + ': ' + (comment || '') + ' ';
+      }
+      return document.createComment(content);
+    };
+
     return compile;
 
     //================================
@@ -2054,8 +2062,7 @@ function $CompileProvider($provide, $$sanitizeUriProvider) {
             terminalPriority = directive.priority;
             $template = $compileNode;
             $compileNode = templateAttrs.$$element =
-                jqLite(document.createComment(' ' + directiveName + ': ' +
-                                              templateAttrs[directiveName] + ' '));
+                jqLite(compile.$createComment(directiveName, templateAttrs[directiveName]));
             compileNode = $compileNode[0];
             replaceWith(jqCollection, sliceArgs($template), compileNode);
 

src/ng/directive/ngIf.js

@@ -78,7 +78,7 @@
     </file>
   </example>
  */
-var ngIfDirective = ['$animate', function($animate) {
+var ngIfDirective = ['$animate', '$compile', function($animate, $compile) {
   return {
     multiElement: true,
     transclude: 'element',
@@ -94,7 +94,7 @@ var ngIfDirective = ['$animate', function($animate) {
             if (!childScope) {
               $transclude(function(clone, newScope) {
                 childScope = newScope;
-                clone[clone.length++] = document.createComment(' end ngIf: ' + $attr.ngIf + ' ');
+                clone[clone.length++] = $compile.$createComment('end ngIf', $attr.ngIf);
                 // Note: We only need the first/last node of the cloned nodes.
                 // However, we need to keep the reference to the jqlite wrapper as it might be changed later
                 // by a directive with templateUrl when its template arrives.

src/ng/directive/ngRepeat.js

@@ -322,7 +322,7 @@
       </file>
     </example>
  */
-var ngRepeatDirective = ['$parse', '$animate', function($parse, $animate) {
+var ngRepeatDirective = ['$parse', '$animate', '$compile', function($parse, $animate, $compile) {
   var NG_REMOVED = '$$NG_REMOVED';
   var ngRepeatMinErr = minErr('ngRepeat');
 
@@ -357,7 +357,7 @@ var ngRepeatDirective = ['$parse', '$animate', function($parse, $animate) {
     $$tlb: true,
     compile: function ngRepeatCompile($element, $attr) {
       var expression = $attr.ngRepeat;
-      var ngRepeatEndComment = document.createComment(' end ngRepeat: ' + expression + ' ');
+      var ngRepeatEndComment = $compile.$createComment('end ngRepeat', expression);
 
       var match = expression.match(/^\s*([\s\S]+?)\s+in\s+([\s\S]+?)(?:\s+as\s+([\s\S]+?))?(?:\s+track\s+by\s+([\s\S]+?))?\s*$/);
 

src/ng/directive/ngSwitch.js

@@ -129,7 +129,7 @@
     </file>
   </example>
  */
-var ngSwitchDirective = ['$animate', function($animate) {
+var ngSwitchDirective = ['$animate', '$compile', function($animate, $compile) {
   return {
     require: 'ngSwitch',
 
@@ -170,7 +170,7 @@ var ngSwitchDirective = ['$animate', function($animate) {
             selectedTransclude.transclude(function(caseElement, selectedScope) {
               selectedScopes.push(selectedScope);
               var anchor = selectedTransclude.element;
-              caseElement[caseElement.length++] = document.createComment(' end ngSwitchWhen: ');
+              caseElement[caseElement.length++] = $compile.$createComment('end ngSwitchWhen');
               var block = { clone: caseElement };
 
               selectedElements.push(block);

src/ngMessages/messages.js

@@ -522,7 +522,10 @@ angular.module('ngMessages', [])
              element.after(contents);
 
              // the anchor is placed for debugging purposes
-             var anchor = jqLite($document[0].createComment(' ngMessagesInclude: ' + src + ' '));
+             var comment = $compile.$createComment ?
+                 $compile.$createComment('ngMessagesInclude', src) :
+                 $document[0].createComment(' ngMessagesInclude: ' + src + ' ');
+             var anchor = jqLite(comment);
              element.after(anchor);
 
              // we don't want to pollute the DOM anymore by keeping an empty directive element

test/ng/compileSpec.js

@@ -10146,4 +10146,28 @@ describe('$compile', function() {
       });
     });
   });
+
+  describe('$createComment', function() {
+    it('should create empty comments if `debugInfoEnabled` is false', function() {
+      module(function($compileProvider) {
+        $compileProvider.debugInfoEnabled(false);
+      });
+
+      inject(function($compile) {
+        var comment = $compile.$createComment('foo', 'bar');
+        expect(comment.data).toBe('');
+      });
+    });
+
+    it('should create descriptive comments if `debugInfoEnabled` is true', function() {
+      module(function($compileProvider) {
+        $compileProvider.debugInfoEnabled(true);
+      });
+
+      inject(function($compile) {
+        var comment = $compile.$createComment('foo', 'bar');
+        expect(comment.data).toBe(' foo: bar ');
+      });
+    });
+  });
 });

test/ng/directive/ngIncludeSpec.js

@@ -401,7 +401,9 @@ describe('ngInclude', function() {
   it('should not compile template if original scope is destroyed', function() {
     module(function($provide) {
       $provide.decorator('$compile', function($delegate) {
-        return jasmine.createSpy('$compile').andCallFake($delegate);
+        var result = jasmine.createSpy('$compile').andCallFake($delegate);
+        result.$createComment = $delegate.$createComment;
+        return result;
       });
     });
     inject(function($rootScope, $httpBackend, $compile) {