JSON parsing of large numbers

src/com/adobe/serialization/json/JSON.as

@@ -66,7 +66,7 @@ package com.adobe.serialization.json
 		 *
 		 * @param s The JSON string representing the object
 		 * @param strict Flag indicating if the decoder should strictly adhere
-		 * 		to the JSON standard or not.  The default of <code>true</code>
+		 * 		to t he JSON standard or not.  The default of <code>true</code>
 		 * 		throws errors if the format does not match the JSON syntax exactly.
 		 * 		Pass <code>false</code> to allow for non-properly-formatted JSON
 		 * 		strings to be decoded with more leniancy.

src/com/adobe/serialization/json/JSONTokenizer.as

@@ -62,6 +62,14 @@ package com.adobe.serialization.json
 		 */
 		private const controlCharsRegExp:RegExp = /[\x00-\x1F]/;
 
+		/**
+		 * The maximum number that can be represented accurately as a double
+		 * in either AS3/ECMA languages. 
+		 *
+		 * See http://stackoverflow.com/questions/4840482/javascript-integer-overflow
+		 */
+		private const MAX_DOUBLE:Number = Math.pow(2,53);
+
 		/**
 		 * Constructs a new JSONDecoder to parse a JSON string
 		 * into a native object.
@@ -520,6 +528,13 @@ package com.adobe.serialization.json
 			// convert the string to a number value
 			var num:Number = Number( input );
 
+			if ( num > MAX_DOUBLE ) 
+			{
+				// Special case for numbers largers than doubles that we can't accurately represent in AS3
+				// We treat these as a string instead.
+				return JSONToken.create( JSONTokenType.STRING, input );
+			}
+
 			if ( isFinite( num ) && !isNaN( num ) )
 			{
 				// the token for the number that we've read

tests/src/com/adobe/serialization/json/JSONTest.as

@@ -236,6 +236,28 @@ package com.adobe.serialization.json
 			expectParseError( "0xFF0033" );
 		}
 
+		/**
+		 * Test decoding numbers that are larger than 2^52 and cannot
+		 * be accurately decoded in Flash. We return them as strings.
+		 */ 
+		public function testLargeNumbers():void
+		{
+			// when this is cast to a number, it gets cast to 10100401822940524
+			var big:String = "{\"val\":10100401822940525}";
+
+			var decoded:Object = JSON.decode( big );
+
+			assertTrue( decoded.val is String );  
+			assertTrue( decoded.val == "10100401822940525" );
+
+
+			var small:String = "{\"val\":100}";
+			decoded = JSON.decode( small );
+
+			assertTrue( decoded.val is Number );
+			assertTrue( decoded.val == 100 );
+		}
+
 		/**
 		 * Non-strict mode allows for NaN as a valid token
 		 */