diff --git a/lib/metagrammar.js b/lib/metagrammar.js
index 96c8134..491acaf 100644
--- a/lib/metagrammar.js
+++ b/lib/metagrammar.js
@@ -85,7 +85,7 @@ PEG.grammarParser = (function(){
           var result = {};
           PEG.ArrayUtils.each($2, function(rule) { result[rule.getName()] = rule; });
           return result;
-         }).apply(this, result1)
+         }).apply(null, result1)
         : null;
       
       
@@ -155,7 +155,7 @@ PEG.grammarParser = (function(){
       var result5 = result6 !== null
         ? (function($1, $2, $3, $4) { 
           return new PEG.Grammar.Rule($1, $2 !== "" ? $2 : null, $4);
-         }).apply(this, result6)
+         }).apply(null, result6)
         : null;
       
       
@@ -253,7 +253,7 @@ PEG.grammarParser = (function(){
                 function(element) { return element[1]; }
               )))
             : $1;
-         }).apply(this, result15)
+         }).apply(null, result15)
         : null;
       
       
@@ -301,7 +301,7 @@ PEG.grammarParser = (function(){
                 $1.length != 1 ? new PEG.Grammar.Sequence($1) : $1[0],
                 $2
               );
-             }).apply(this, result26)
+             }).apply(null, result26)
         : null;
       if (result25 !== null) {
         var result21 = result25;
@@ -313,7 +313,7 @@ PEG.grammarParser = (function(){
           var result24 = this._parse_prefixed(context);
         }
         var result22 = result23 !== null
-          ? (function($1) {  return $1.length != 1 ? new PEG.Grammar.Sequence($1) : $1[0];  }).call(this, result23)
+          ? (function($1) {  return $1.length != 1 ? new PEG.Grammar.Sequence($1) : $1[0];  })(result23)
           : null;
         if (result22 !== null) {
           var result21 = result22;
@@ -357,7 +357,7 @@ PEG.grammarParser = (function(){
         this._pos = savedPos6;
       }
       var result36 = result37 !== null
-        ? (function($1, $2) {  return new PEG.Grammar.AndPredicate($2);  }).apply(this, result37)
+        ? (function($1, $2) {  return new PEG.Grammar.AndPredicate($2);  }).apply(null, result37)
         : null;
       if (result36 !== null) {
         var result30 = result36;
@@ -377,7 +377,7 @@ PEG.grammarParser = (function(){
           this._pos = savedPos5;
         }
         var result32 = result33 !== null
-          ? (function($1, $2) {  return new PEG.Grammar.NotPredicate($2);  }).apply(this, result33)
+          ? (function($1, $2) {  return new PEG.Grammar.NotPredicate($2);  }).apply(null, result33)
           : null;
         if (result32 !== null) {
           var result30 = result32;
@@ -426,7 +426,7 @@ PEG.grammarParser = (function(){
         this._pos = savedPos9;
       }
       var result50 = result51 !== null
-        ? (function($1, $2) {  return new PEG.Grammar.Optional($1);    }).apply(this, result51)
+        ? (function($1, $2) {  return new PEG.Grammar.Optional($1);    }).apply(null, result51)
         : null;
       if (result50 !== null) {
         var result40 = result50;
@@ -446,7 +446,7 @@ PEG.grammarParser = (function(){
           this._pos = savedPos8;
         }
         var result46 = result47 !== null
-          ? (function($1, $2) {  return new PEG.Grammar.ZeroOrMore($1);  }).apply(this, result47)
+          ? (function($1, $2) {  return new PEG.Grammar.ZeroOrMore($1);  }).apply(null, result47)
           : null;
         if (result46 !== null) {
           var result40 = result46;
@@ -466,7 +466,7 @@ PEG.grammarParser = (function(){
             this._pos = savedPos7;
           }
           var result42 = result43 !== null
-            ? (function($1, $2) {  return new PEG.Grammar.OneOrMore($1);   }).apply(this, result43)
+            ? (function($1, $2) {  return new PEG.Grammar.OneOrMore($1);   }).apply(null, result43)
             : null;
           if (result42 !== null) {
             var result40 = result42;
@@ -557,28 +557,28 @@ PEG.grammarParser = (function(){
         this._pos = savedPos11;
       }
       var result66 = result67 !== null
-        ? (function($1, $2) {  return new PEG.Grammar.RuleRef($1);  }).apply(this, result67)
+        ? (function($1, $2) {  return new PEG.Grammar.RuleRef($1);  }).apply(null, result67)
         : null;
       if (result66 !== null) {
         var result54 = result66;
       } else {
         var result65 = this._parse_literal(context);
         var result64 = result65 !== null
-          ? (function($1) {  return new PEG.Grammar.Literal($1);  }).call(this, result65)
+          ? (function($1) {  return new PEG.Grammar.Literal($1);  })(result65)
           : null;
         if (result64 !== null) {
           var result54 = result64;
         } else {
           var result63 = this._parse_dot(context);
           var result62 = result63 !== null
-            ? (function($1) {  return new PEG.Grammar.Any();        }).call(this, result63)
+            ? (function($1) {  return new PEG.Grammar.Any();        })(result63)
             : null;
           if (result62 !== null) {
             var result54 = result62;
           } else {
             var result61 = this._parse_class(context);
             var result60 = result61 !== null
-              ? (function($1) {  return new PEG.Grammar.Class($1);    }).call(this, result61)
+              ? (function($1) {  return new PEG.Grammar.Class($1);    })(result61)
               : null;
             if (result60 !== null) {
               var result54 = result60;
@@ -604,7 +604,7 @@ PEG.grammarParser = (function(){
                 this._pos = savedPos10;
               }
               var result55 = result56 !== null
-                ? (function($1, $2, $3) {  return $2;  }).apply(this, result56)
+                ? (function($1, $2, $3) {  return $2;  }).apply(null, result56)
                 : null;
               if (result55 !== null) {
                 var result54 = result55;
@@ -652,7 +652,7 @@ PEG.grammarParser = (function(){
         this._pos = savedPos14;
       }
       var result75 = result76 !== null
-        ? (function($1, $2) {  return $1.substr(1, $1.length - 2);  }).apply(this, result76)
+        ? (function($1, $2) {  return $1.substr(1, $1.length - 2);  }).apply(null, result76)
         : null;
       context.reportMatchFailures = savedReportMatchFailures;
       if (context.reportMatchFailures && result75 === null) {
@@ -739,7 +739,7 @@ PEG.grammarParser = (function(){
         this._pos = savedPos15;
       }
       var result79 = result80 !== null
-        ? (function($1, $2, $3) {  return $1 + $2.join("") + $3;  }).apply(this, result80)
+        ? (function($1, $2, $3) {  return $1 + $2.join("") + $3;  }).apply(null, result80)
         : null;
       
       
@@ -773,7 +773,7 @@ PEG.grammarParser = (function(){
         var result88 = null;
       }
       var result87 = result88 !== null
-        ? (function($1) {  return $1.join("");  }).call(this, result88)
+        ? (function($1) {  return $1.join("");  })(result88)
         : null;
       
       
@@ -806,7 +806,7 @@ PEG.grammarParser = (function(){
         }
       }
       var result90 = result91 !== null
-        ? (function($1) {  return $1;  }).call(this, result91)
+        ? (function($1) {  return $1;  })(result91)
         : null;
       
       
@@ -852,7 +852,7 @@ PEG.grammarParser = (function(){
         this._pos = savedPos16;
       }
       var result92 = result93 !== null
-        ? (function($1, $2) {  return $1;  }).apply(this, result93)
+        ? (function($1, $2) {  return $1;  }).apply(null, result93)
         : null;
       
       
@@ -898,7 +898,7 @@ PEG.grammarParser = (function(){
         this._pos = savedPos17;
       }
       var result96 = result97 !== null
-        ? (function($1, $2) {  return $1;  }).apply(this, result97)
+        ? (function($1, $2) {  return $1;  }).apply(null, result97)
         : null;
       
       
@@ -944,7 +944,7 @@ PEG.grammarParser = (function(){
         this._pos = savedPos18;
       }
       var result100 = result101 !== null
-        ? (function($1, $2) {  return $1;  }).apply(this, result101)
+        ? (function($1, $2) {  return $1;  }).apply(null, result101)
         : null;
       
       
@@ -990,7 +990,7 @@ PEG.grammarParser = (function(){
         this._pos = savedPos19;
       }
       var result104 = result105 !== null
-        ? (function($1, $2) {  return $1;  }).apply(this, result105)
+        ? (function($1, $2) {  return $1;  }).apply(null, result105)
         : null;
       
       
@@ -1036,7 +1036,7 @@ PEG.grammarParser = (function(){
         this._pos = savedPos20;
       }
       var result108 = result109 !== null
-        ? (function($1, $2) {  return $1;  }).apply(this, result109)
+        ? (function($1, $2) {  return $1;  }).apply(null, result109)
         : null;
       
       
@@ -1082,7 +1082,7 @@ PEG.grammarParser = (function(){
         this._pos = savedPos21;
       }
       var result112 = result113 !== null
-        ? (function($1, $2) {  return $1;  }).apply(this, result113)
+        ? (function($1, $2) {  return $1;  }).apply(null, result113)
         : null;
       
       
@@ -1128,7 +1128,7 @@ PEG.grammarParser = (function(){
         this._pos = savedPos22;
       }
       var result116 = result117 !== null
-        ? (function($1, $2) {  return $1;  }).apply(this, result117)
+        ? (function($1, $2) {  return $1;  }).apply(null, result117)
         : null;
       
       
@@ -1174,7 +1174,7 @@ PEG.grammarParser = (function(){
         this._pos = savedPos23;
       }
       var result120 = result121 !== null
-        ? (function($1, $2) {  return $1;  }).apply(this, result121)
+        ? (function($1, $2) {  return $1;  }).apply(null, result121)
         : null;
       
       
@@ -1220,7 +1220,7 @@ PEG.grammarParser = (function(){
         this._pos = savedPos24;
       }
       var result124 = result125 !== null
-        ? (function($1, $2) {  return $1;  }).apply(this, result125)
+        ? (function($1, $2) {  return $1;  }).apply(null, result125)
         : null;
       
       
@@ -1266,7 +1266,7 @@ PEG.grammarParser = (function(){
         this._pos = savedPos25;
       }
       var result128 = result129 !== null
-        ? (function($1, $2) {  return $1;  }).apply(this, result129)
+        ? (function($1, $2) {  return $1;  }).apply(null, result129)
         : null;
       
       
@@ -1421,7 +1421,7 @@ PEG.grammarParser = (function(){
       var result132 = result133 !== null
         ? (function($1, $2, $3) { 
           return $1 + $2.join("");
-         }).apply(this, result133)
+         }).apply(null, result133)
         : null;
       context.reportMatchFailures = savedReportMatchFailures;
       if (context.reportMatchFailures && result132 === null) {
@@ -1472,7 +1472,7 @@ PEG.grammarParser = (function(){
         this._pos = savedPos27;
       }
       var result145 = result146 !== null
-        ? (function($1, $2) {  return $1;  }).apply(this, result146)
+        ? (function($1, $2) {  return $1;  }).apply(null, result146)
         : null;
       context.reportMatchFailures = savedReportMatchFailures;
       if (context.reportMatchFailures && result145 === null) {
@@ -1539,7 +1539,7 @@ PEG.grammarParser = (function(){
         this._pos = savedPos28;
       }
       var result151 = result152 !== null
-        ? (function($1, $2, $3) {  return $2.join("");  }).apply(this, result152)
+        ? (function($1, $2, $3) {  return $2.join("");  }).apply(null, result152)
         : null;
       
       
@@ -1678,7 +1678,7 @@ PEG.grammarParser = (function(){
         this._pos = savedPos29;
       }
       var result164 = result165 !== null
-        ? (function($1, $2) {  return $2;  }).apply(this, result165)
+        ? (function($1, $2) {  return $2;  }).apply(null, result165)
         : null;
       
       
@@ -1743,7 +1743,7 @@ PEG.grammarParser = (function(){
         this._pos = savedPos31;
       }
       var result172 = result173 !== null
-        ? (function($1, $2, $3) {  return $2.join("");  }).apply(this, result173)
+        ? (function($1, $2, $3) {  return $2.join("");  }).apply(null, result173)
         : null;
       
       
@@ -1882,7 +1882,7 @@ PEG.grammarParser = (function(){
         this._pos = savedPos32;
       }
       var result185 = result186 !== null
-        ? (function($1, $2) {  return $2;  }).apply(this, result186)
+        ? (function($1, $2) {  return $2;  }).apply(null, result186)
         : null;
       
       
@@ -1991,7 +1991,7 @@ PEG.grammarParser = (function(){
       var result193 = result194 !== null
         ? (function($1, $2, $3, $4, $5) { 
           return $2 + $3.join("");
-         }).apply(this, result194)
+         }).apply(null, result194)
         : null;
       context.reportMatchFailures = savedReportMatchFailures;
       if (context.reportMatchFailures && result193 === null) {
@@ -2059,7 +2059,7 @@ PEG.grammarParser = (function(){
           return PEG.RegExpUtils.quoteForClass($1)
             + "-"
             + PEG.RegExpUtils.quoteForClass($3);
-         }).apply(this, result205)
+         }).apply(null, result205)
         : null;
       
       
@@ -2086,7 +2086,7 @@ PEG.grammarParser = (function(){
       var result209 = result210 !== null
         ? (function($1) { 
           return PEG.RegExpUtils.quoteForClass($1);
-         }).call(this, result210)
+         })(result210)
         : null;
       
       
@@ -2225,7 +2225,7 @@ PEG.grammarParser = (function(){
         this._pos = savedPos36;
       }
       var result218 = result219 !== null
-        ? (function($1, $2) {  return $2;  }).apply(this, result219)
+        ? (function($1, $2) {  return $2;  }).apply(null, result219)
         : null;
       
       
@@ -2339,7 +2339,7 @@ PEG.grammarParser = (function(){
             .replace("r", "\r")
             .replace("t", "\t")
             .replace("v", "\x0B") // IE does not recognize "\v".
-         }).apply(this, result227)
+         }).apply(null, result227)
         : null;
       
       
@@ -2395,7 +2395,7 @@ PEG.grammarParser = (function(){
         this._pos = savedPos40;
       }
       var result236 = result237 !== null
-        ? (function($1, $2) {  return "\0";  }).apply(this, result237)
+        ? (function($1, $2) {  return "\0";  }).apply(null, result237)
         : null;
       
       
@@ -2449,7 +2449,7 @@ PEG.grammarParser = (function(){
       var result241 = result242 !== null
         ? (function($1, $2, $3) { 
           return String.fromCharCode(parseInt("0x" + $2 + $3));
-         }).apply(this, result242)
+         }).apply(null, result242)
         : null;
       
       
@@ -2515,7 +2515,7 @@ PEG.grammarParser = (function(){
       var result246 = result247 !== null
         ? (function($1, $2, $3, $4, $5) { 
           return String.fromCharCode(parseInt("0x" + $2 + $3 + $4 + $5));
-         }).apply(this, result247)
+         }).apply(null, result247)
         : null;
       
       
@@ -2561,7 +2561,7 @@ PEG.grammarParser = (function(){
         this._pos = savedPos44;
       }
       var result253 = result254 !== null
-        ? (function($1, $2) {  return $2;  }).apply(this, result254)
+        ? (function($1, $2) {  return $2;  }).apply(null, result254)
         : null;