Implement postProcessor callback feature for less.ls browser environment #1835

Gruntfile.js

@@ -214,6 +214,14 @@ module.exports = function(grunt) {
           specs: 'test/browser/runner-global-vars-spec.js',
           outfile: 'tmp/browser/test-runner-global-vars.html'
         }
+      },
+      postProcessor: {
+        src: ['test/browser/less/postProcessor/*.less'],
+        options: {
+          helpers: 'test/browser/runner-postProcessor-options.js',
+          specs: 'test/browser/runner-postProcessor.js',
+          outfile: 'tmp/browser/test-postProcessor.html'
+        }
       }
     },
 

lib/less/browser.js

@@ -159,6 +159,13 @@ function createCSS(styles, sheet, lastModified) {
     }
 }
 
+function postProcessCSS(styles) {
+    if (less.postProcessor && typeof less.postProcessor === 'function') {
+        styles = less.postProcessor.call(styles, styles) || styles;
+    }
+    return styles;
+}
+
 function errorHTML(e, rootHref) {
     var id = 'less-error-message:' + extractId(rootHref || "");
     var template = '<li><label>{line}</label><pre class="{class}">{content}</pre></li>';
@@ -575,7 +582,9 @@ function initRunningMode(){
                     if (e) {
                         error(e, sheet.href);
                     } else if (root) {
-                        createCSS(root.toCSS(less), sheet, env.lastModified);
+                        var styles = root.toCSS(less);
+                        styles = postProcessCSS(styles);
+                        createCSS(styles, sheet, env.lastModified);
                     }
                 });
             }
@@ -645,7 +654,9 @@ less.refresh = function (reload, modifyVars) {
             log("loading " + sheet.href + " from cache.", logLevel.info);
         } else {
             log("parsed " + sheet.href + " successfully.", logLevel.info);
-            createCSS(root.toCSS(less), sheet, env.lastModified);
+            var styles = root.toCSS(less);
+            styles = postProcessCSS(styles);
+            createCSS(styles, sheet, env.lastModified);
         }
         log("css for " + sheet.href + " generated in " + (new Date() - endTime) + 'ms', logLevel.info);
         if (env.remaining === 0) {

test/browser/css/postProcessor/postProcessor.css

@@ -0,0 +1,4 @@
+hr {height:50px;}
+.test {
+  color: #ffffff;
+}

test/browser/less/postProcessor/postProcessor.less

@@ -0,0 +1,4 @@
+@color: white;
+.test {
+    color: @color;
+}

test/browser/runner-postProcessor-options.js

@@ -0,0 +1,4 @@
+var less = {};
+less.postProcessor = function(styles) {
+    return 'hr {height:50px;}\n' + styles;
+};

test/browser/runner-postProcessor.js

@@ -0,0 +1,3 @@
+describe("less.js postProcessor", function() {
+  testLessEqualsInDocument();
+});