Adding gsub function

lib/less/functions.js

@@ -213,6 +213,13 @@ tree.functions = {
     escape: function (str) {
         return new(tree.Anonymous)(encodeURI(str.value).replace(/=/g, "%3D").replace(/:/g, "%3A").replace(/#/g, "%23").replace(/;/g, "%3B").replace(/\(/g, "%28").replace(/\)/g, "%29"));
     },
+    gsub: function (str, regexp, replacement) {
+        var str = str.value;
+
+        str = str.replace(new RegExp(regexp.value, "g"), replacement.value);
+
+        return new(tree.Quoted)('"' + str + '"', str)
+    },
     '%': function (quoted /* arg, arg, ...*/) {
         var args = Array.prototype.slice.call(arguments, 1),
             str = quoted.value;

test/css/functions.css

@@ -8,6 +8,7 @@
 }
 #built-in {
   escaped: -Some::weird(#thing, y);
+  gsub: "Hello, World!";
   lighten: #ffcccc;
   darken: #330000;
   saturate: #203c31;

test/less/functions.less

@@ -12,6 +12,7 @@
 #built-in {
   @r: 32;
   escaped: e("-Some::weird(#thing, y)");
+  gsub: gsub("Hello, Foo.", "Foo\.$", "World!");
   lighten: lighten(#ff0000, 40%);
   darken: darken(#ff0000, 40%);
   saturate: saturate(#29332f, 20%);