Fix the Reader#readWhile implementation.

Previously it would read an extra character after the filter returned
false.  Luckily, this function does not appear to be used (yet) anywhere
else in the parser.

Author: cscott

src/util/StringReader.js

@@ -204,11 +204,11 @@ StringReader.prototype = {
     readWhile: function(filter){
 
         var buffer = "",
-            c = this.read();
+            c = this.peek();
 
         while(c !== null && filter(c)){
-            buffer += c;
-            c = this.read();
+            buffer += this.read();
+            c = this.peek();
         }
 
         return buffer;

tests/util/StringReader.js

@@ -172,6 +172,23 @@
             Assert.areEqual(testString, result);
             Assert.areEqual(1, reader.getLine());
             Assert.areEqual(13, reader.getCol());
+        },
+
+        /*
+         * Tests that the filter function works.
+         */
+        testReadWhileFilter: function(){
+            var testString = "Hello world!",
+                reader = new StringReader(testString);
+
+            var result = reader.readWhile(function(c){
+                return c !== ' ';
+            });
+
+            Assert.areEqual('Hello', result);
+            Assert.areEqual(reader.peek(), ' ');
+            Assert.areEqual(1, reader.getLine());
+            Assert.areEqual(6, reader.getCol());
         }
     }));