Implemented and used PEG.ArrayUtils.each.

lib/metagrammar.js

@@ -54,7 +54,7 @@ PEG.grammarParser = (function(){
     var result0 = result1 !== null
       ? (function() { 
         var result = {};
-        for (var i = 0; i < (arguments[1]).length; i++) { result[(arguments[1])[i].getName()] = (arguments[1])[i]; }
+        PEG.ArrayUtils.each((arguments[1]), function(rule) { result[rule.getName()] = rule; });
         return result;
        }).apply(this, result1)
       : null;

lib/metagrammar.pegjs

@@ -1,6 +1,6 @@
 grammar: __ rule+ {
   var result = {};
-  for (var i = 0; i < $2.length; i++) { result[$2[i].getName()] = $2[i]; }
+  PEG.ArrayUtils.each($2, function(rule) { result[rule.getName()] = rule; });
   return result;
 }
 

lib/runtime.js

@@ -13,6 +13,13 @@ PEG = {};
 /* Array manipulation utility functions. */
 
 PEG.ArrayUtils = {
+  each: function(array, callback) {
+    var length = array.length;
+    for (var i = 0; i < length; i++) {
+      callback(array[i]);
+    }
+  },
+
   map: function(array, callback) {
     var result = [];
     var length = array.length;

test/runtime-test.js

@@ -4,6 +4,19 @@
 
 module("PEG.ArrayUtils");
 
+test("each", function() {
+  var sum;
+  function increment(x) { sum += x; }
+
+  sum = 0;
+  PEG.ArrayUtils.each([], increment);
+  strictEqual(sum, 0);
+
+  sum = 0;
+  PEG.ArrayUtils.each([1, 2, 3], increment);
+  strictEqual(sum, 6);
+});
+
 test("map", function() {
   function square(x) { return x * x; }