Allow [] to resolve to last declaration's value (#3256)

Author: matthew-dean

lib/less/parser/parser.js

@@ -1121,7 +1121,7 @@ var Parser = function Parser(context, imports, fileInfo) {
                         parserInput.save();
                         args = null;
                         rule = this.lookupValue();
-                        if (!rule) {
+                        if (!rule && rule !== '') {
                             parserInput.restore();
                             break;
                         }
@@ -1141,14 +1141,14 @@ var Parser = function Parser(context, imports, fileInfo) {
                         return;
                     }
 
-                    var name = parserInput.$re(/^(?:@{0,2}|\$)[_a-zA-Z0-9-]+/);
+                    var name = parserInput.$re(/^(?:[@$]{0,2})[_a-zA-Z0-9-]*/);
 
                     if (!parserInput.$char(']')) {
                         parserInput.restore();
                         return;
                     } 
 
-                    if (name) {
+                    if (name || name === '') {
                         parserInput.forget();
                         return name;
                     }

lib/less/tree/namespace-value.js

@@ -13,22 +13,24 @@ var NamespaceValue = function (ruleCall, lookups, important, index, fileInfo) {
 NamespaceValue.prototype = new Node();
 NamespaceValue.prototype.type = 'NamespaceValue';
 NamespaceValue.prototype.eval = function (context) {
-    var i, j, name, found,
-        rules = this.value.eval(context);
+    var i, j, name, rules = this.value.eval(context);
 
     for (i = 0; i < this.lookups.length; i++) {
         name = this.lookups[i];
 
         /**
          * Eval'd DRs return rulesets.
          * Eval'd mixins return rules, so let's make a ruleset if we need it.
-         * We need to do this because of late parsing of properties
+         * We need to do this because of late parsing of values
          */
         if (Array.isArray(rules)) {
             rules = new Ruleset([new Selector()], rules);
         }
 
-        if (name.charAt(0) === '@') {
+        if (name === '') {
+            rules = rules.lastDeclaration();
+        }
+        else if (name.charAt(0) === '@') {
             if (name.charAt(1) === '@') {
                 name = '@' + new Variable(name.substr(1)).eval(context).value;
             }
@@ -44,13 +46,19 @@ NamespaceValue.prototype.eval = function (context) {
             }
         }
         else {
+            if (name.substring(0, 2) === '$@') {
+                name = '$' + new Variable(name.substr(1)).eval(context).value;
+            }
+            else {
+                name = name.charAt(0) === '$' ? name : '$' + name;
+            }
             if (rules.properties) {
-                rules = rules.property(name.charAt(0) === '$' ? name : '$' + name);
+                rules = rules.property(name);
             }
 
             if (!rules) {
                 throw { type: 'Name',
-                    message: 'property "' + name + '" not found',
+                    message: 'property "' + name.substr(1) + '" not found',
                     filename: this.fileInfo().filename,
                     index: this.getIndex() };
             }

lib/less/tree/ruleset.js

@@ -318,6 +318,14 @@ Ruleset.prototype.property = function (name) {
         return this.parseValue(decl);
     }
 };
+Ruleset.prototype.lastDeclaration = function () {
+    for (var i = this.rules.length; i > 0; i--) {
+        var decl = this.rules[i - 1];
+        if (decl instanceof Declaration) {
+            return this.parseValue(decl);
+        }
+    }
+};
 Ruleset.prototype.parseValue = function(toParse) {
     var self = this;
     function transformDeclaration(decl) {

test/css/edge/namespacing-1.css renamed to test/css/namespacing/namespacing-1.css

@@ -0,0 +1,4 @@
+.foo {
+  width: 20px;
+  bar: val;
+}

test/css/edge/namespacing-2.css renamed to test/css/namespacing/namespacing-2.css

@@ -7,7 +7,7 @@ console.log('\n' + stylize('Less', 'underline') + '\n');
 
 lessTester.prepBomTest();
 var testMap = [
-    [{}, 'edge/'],
+    [{}, 'namespacing/'],
     [{
         strictMath: false, 
         relativeUrls: true, 

test/css/edge/namespacing-3.css renamed to test/css/namespacing/namespacing-3.css

@@ -0,0 +1,11 @@
+.add(@a, @b) {
+  @r: @a + @b;
+}
+.foo {
+  width: .add(10px, 10px)[];
+  bar: @return[];
+}
+
+@return: {
+  single: val;
+}

test/css/edge/namespacing-4.css renamed to test/css/namespacing/namespacing-4.css

@@ -19,7 +19,7 @@
   keyword: small;
 }
 
-@media #ns.breakpoint(.valToGet[keyword])[@max] {
+@media #ns.breakpoint(.valToGet[])[@max] {
   .selector {
     prop: val;
   }