add ability to bind varargs

Author: cloudhead

lib/less/parser.js

@@ -807,6 +807,10 @@ less.Parser = function Parser(env) {
                                     if ($(':')) {
                                         value = expect(this.expression, 'expected expression');
                                         params.push({ name: param.name, value: value });
+                                    } else if ($(/^\.{3}/)) {
+                                        params.push({ name: param.name, variadic: true });
+                                        variadic = true;
+                                        break;
                                     } else {
                                         params.push({ name: param.name });
                                     }

lib/less/tree/mixin.js

@@ -69,12 +69,18 @@ tree.mixin.Definition.prototype = {
     rulesets:  function ()     { return this.parent.rulesets.apply(this) },
 
     evalParams: function (env, args) {
-        var frame = new(tree.Ruleset)(null, []);
+        var frame = new(tree.Ruleset)(null, []), varargs;
 
-        for (var i = 0, val; i < this.params.length; i++) {
-            if (this.params[i].name) {
-                if (val = (args && args[i]) || this.params[i].value) {
-                    frame.rules.unshift(new(tree.Rule)(this.params[i].name, val.eval(env)));
+        for (var i = 0, val, name; i < this.params.length; i++) {
+            if (name = this.params[i].name) {
+                if (this.params[i].variadic && args) {
+                    varargs = [];
+                    for (var j = i; j < args.length; j++) {
+                        varargs.push(args[j].eval(env));
+                    }
+                    frame.rules.unshift(new(tree.Rule)(name, new(tree.Expression)(varargs).eval(env)));
+                } else if (val = (args && args[i]) || this.params[i].value) {
+                    frame.rules.unshift(new(tree.Rule)(name, val.eval(env)));
                 } else {
                     throw { type: 'Runtime', message: "wrong number of arguments for " + this.name +
                             ' (' + args.length + ' for ' + this.arity + ')' };
@@ -84,7 +90,7 @@ tree.mixin.Definition.prototype = {
         return frame;
     },
     eval: function (env, args, important) {
-        var frame = this.evalParams(env, args), context, _arguments = [], rules;
+        var frame = this.evalParams(env, args), context, _arguments = [], rules, start;
 
         for (var i = 0; i < Math.max(this.params.length, args && args.length); i++) {
             _arguments.push(args[i] || this.params[i].value);

test/css/mixins-args.css

@@ -66,8 +66,9 @@ body {
   width: 0px;
 }
 .arguments4 {
-  border: 4 2;
-  width: 4;
+  border: 0 1 2 3 4;
+  rest: 1 2 3 4;
+  width: 0;
 }
 .edge-case {
   border: "{";

test/less/mixins-args.less

@@ -121,12 +121,13 @@ body {
     .mixin-arguments;
 }
 
-.mixin-arguments2 (@width, ...) {
+.mixin-arguments2 (@width, @rest...) {
     border: @arguments;
+    rest: @rest;
     width: @width;
 }
 .arguments4 {
-    .mixin-arguments2(4, 2);
+    .mixin-arguments2(0, 1, 2, 3, 4);
 }
 
 // Edge cases