/*

Adobe Systems Incorporated(r) Source Code License Agreement

Copyright(c) 2005 Adobe Systems Incorporated. All rights reserved.

	

Please read this Source Code License Agreement carefully before using

the source code.

	

Adobe Systems Incorporated grants to you a perpetual, worldwide, non-exclusive,

no-charge, royalty-free, irrevocable copyright license, to reproduce,

prepare derivative works of, publicly display, publicly perform, and

distribute this source code and such derivative works in source or

object code form without any attribution requirements.

	

The name "Adobe Systems Incorporated" must not be used to endorse or promote products

derived from the source code without prior written permission.

	

You agree to indemnify, hold harmless and defend Adobe Systems Incorporated from and

against any loss, damage, claims or lawsuits, including attorney's

fees that arise or result from your use or distribution of the source

code.

	

THIS SOURCE CODE IS PROVIDED "AS IS" AND "WITH ALL FAULTS", WITHOUT

ANY TECHNICAL SUPPORT OR ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING,

BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS

FOR A PARTICULAR PURPOSE ARE DISCLAIMED. ALSO, THERE IS NO WARRANTY OF

NON-INFRINGEMENT, TITLE OR QUIET ENJOYMENT. IN NO EVENT SHALL MACROMEDIA

OR ITS SUPPLIERS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,

EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,

PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;

OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,

WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR

OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOURCE CODE, EVEN IF

ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

*/



package com.adobe.serialization.json {



	public class JSONDecoder {

		

		/** The value that will get parsed from the JSON string */

		private var value:*;

		

		/** The tokenizer designated to read the JSON string */

		private var tokenizer:JSONTokenizer;

		

		/** The current token from the tokenizer */

		private var token:JSONToken;

		

		/**

		 * Constructs a new JSONDecoder to parse a JSON string 

		 * into a native object.

		 *

		 * @param s The JSON string to be converted

		 *		into a native object

		 * @langversion ActionScript 3.0

		 * @playerversion Flash 9.0

		 * @tiptext

		 */

		public function JSONDecoder( s:String ) {

			

			tokenizer = new JSONTokenizer( s );

			

			nextToken();

			value = parseValue();

		}

		

		/**

		 * Gets the internal object that was created by parsing

		 * the JSON string passed to the constructor.

		 *

		 * @return The internal object representation of the JSON

		 * 		string that was passed to the constructor

		 * @langversion ActionScript 3.0

		 * @playerversion Flash 9.0

		 * @tiptext

		 */

		public function getValue():* {

			return value;

		}

		

		/**

		 * Returns the next token from the tokenzier reading

		 * the JSON string

		 */

		private function nextToken():JSONToken {

			return token = tokenizer.getNextToken();

		}

		

		/**

		 * Attempt to parse an array

		 */

		private function parseArray():Array {

			// create an array internally that we're going to attempt

			// to parse from the tokenizer

			var a:Array = new Array();

			

			// grab the next token from the tokenizer to move

			// past the opening [

			nextToken();

			

			// check to see if we have an empty array

			if ( token.type == JSONTokenType.RIGHT_BRACKET ) {

				// we're done reading the array, so return it

				return a;

			}

			

			// deal with elements of the array, and use an "infinite"

			// loop because we could have any amount of elements

			while ( true ) {

				// read in the value and add it to the array

				a.push ( parseValue() );

			

				// after the value there should be a ] or a ,

				nextToken();

				

				if ( token.type == JSONTokenType.RIGHT_BRACKET ) {

					// we're done reading the array, so return it

					return a;

				} else if ( token.type == JSONTokenType.COMMA ) {

					// move past the comma and read another value

					nextToken();

				} else {

					tokenizer.parseError( "Expecting ] or , but found " + token.value );

				}

			}

            return null;

		}

		

		/**

		 * Attempt to parse an object

		 */

		private function parseObject():Object {

			// create the object internally that we're going to

			// attempt to parse from the tokenizer

			var o:Object = new Object();

						

			// store the string part of an object member so

			// that we can assign it a value in the object

			var key:String

			

			// grab the next token from the tokenizer

			nextToken();

			

			// check to see if we have an empty object

			if ( token.type == JSONTokenType.RIGHT_BRACE ) {

				// we're done reading the object, so return it

				return o;

			}

			

			// deal with members of the object, and use an "infinite"

			// loop because we could have any amount of members

			while ( true ) {

			

				if ( token.type == JSONTokenType.STRING ) {

					// the string value we read is the key for the object

					key = String( token.value );

					

					// move past the string to see what's next

					nextToken();

					

					// after the string there should be a :

					if ( token.type == JSONTokenType.COLON ) {

						

						// move past the : and read/assign a value for the key

						nextToken();

						o[key] = parseValue();	

						

						// move past the value to see what's next

						nextToken();

						

						// after the value there's either a } or a ,

						if ( token.type == JSONTokenType.RIGHT_BRACE ) {

							// // we're done reading the object, so return it

							return o;

							

						} else if ( token.type == JSONTokenType.COMMA ) {

							// skip past the comma and read another member

							nextToken();

						} else {

							tokenizer.parseError( "Expecting } or , but found " + token.value );

						}

					} else {

						tokenizer.parseError( "Expecting : but found " + token.value );

					}

				} else {

					tokenizer.parseError( "Expecting string but found " + token.value );

				}

			}

            return null;

		}

		

		/**

		 * Attempt to parse a value

		 */

		private function parseValue():Object

		{

			// Catch errors when the input stream ends abruptly

			if ( token == null )

			{

				tokenizer.parseError( "Unexpected end of input" );

			}

					

			switch ( token.type ) {

				case JSONTokenType.LEFT_BRACE:

					return parseObject();

					

				case JSONTokenType.LEFT_BRACKET:

					return parseArray();

					

				case JSONTokenType.STRING:

				case JSONTokenType.NUMBER:

				case JSONTokenType.TRUE:

				case JSONTokenType.FALSE:

				case JSONTokenType.NULL:

					return token.value;



				default:

					tokenizer.parseError( "Unexpected " + token.value );

					

			}

            return null;

		}

	}

}