diff --git a/lib/parser.js b/lib/parser.js
index 5337aa7..873f854 100644
--- a/lib/parser.js
+++ b/lib/parser.js
@@ -337,7 +337,7 @@ function peg$parse(input, options) {
       peg$c98 = function(inverted, parts, ignoreCase) {
             return {
               type:       "class",
-              parts:      filterEmptyStrings(parts),
+              parts:      parts.filter(function(part) { return part !== ""; }),
               inverted:   inverted !== null,
               ignoreCase: ignoreCase !== null,
               location:   location()
@@ -4984,30 +4984,12 @@ function peg$parse(input, options) {
       "!": "semantic_not"
     };
 
-    function filterEmptyStrings(array) {
-      var result = [], i;
-
-      for (i = 0; i < array.length; i++) {
-        if (array[i] !== "") {
-          result.push(array[i]);
-        }
-      }
-
-      return result;
-    }
-
     function extractOptional(optional, index) {
       return optional ? optional[index] : null;
     }
 
     function extractList(list, index) {
-      var result = new Array(list.length), i;
-
-      for (i = 0; i < list.length; i++) {
-        result[i] = list[i][index];
-      }
-
-      return result;
+      return list.map(function(element) { return element[index]; });
     }
 
     function buildList(head, tail, index) {
diff --git a/src/parser.pegjs b/src/parser.pegjs
index 346dcf5..6c5da4a 100644
--- a/src/parser.pegjs
+++ b/src/parser.pegjs
@@ -41,30 +41,12 @@
     "!": "semantic_not"
   };
 
-  function filterEmptyStrings(array) {
-    var result = [], i;
-
-    for (i = 0; i < array.length; i++) {
-      if (array[i] !== "") {
-        result.push(array[i]);
-      }
-    }
-
-    return result;
-  }
-
   function extractOptional(optional, index) {
     return optional ? optional[index] : null;
   }
 
   function extractList(list, index) {
-    var result = new Array(list.length), i;
-
-    for (i = 0; i < list.length; i++) {
-      result[i] = list[i][index];
-    }
-
-    return result;
+    return list.map(function(element) { return element[index]; });
   }
 
   function buildList(head, tail, index) {
@@ -382,7 +364,7 @@ CharacterClassMatcher "character class"
     {
       return {
         type:       "class",
-        parts:      filterEmptyStrings(parts),
+        parts:      parts.filter(function(part) { return part !== ""; }),
         inverted:   inverted !== null,
         ignoreCase: ignoreCase !== null,
         location:   location()