comparison bindings/as3/ext/com/adobe/serialization/json/JSONDecoder.as @ 732:3a0b9700b3d2

* Initial AS3 commit

+/*
+  Copyright (c) 2008, Adobe Systems Incorporated
+  All rights reserved.
+
+  Redistribution and use in source and binary forms, with or without 
+  modification, are permitted provided that the following conditions are
+  met:
+
+  * Redistributions of source code must retain the above copyright notice, 
+    this list of conditions and the following disclaimer.
+  
+  * Redistributions in binary form must reproduce the above copyright
+    notice, this list of conditions and the following disclaimer in the 
+    documentation and/or other materials provided with the distribution.
+  
+  * Neither the name of Adobe Systems Incorporated nor the names of its 
+    contributors may be used to endorse or promote products derived from 
+    this software without specific prior written permission.
+
+  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
+  IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+  THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+  PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR 
+  CONTRIBUTORS 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
+  SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*/
+
+package com.adobe.serialization.json
+{
+	
+	public class JSONDecoder
+	{	
+	
+		/** 
+		 * Flag indicating if the parser should be strict about the format
+		 * of the JSON string it is attempting to decode.
+		 */
+		private var strict:Boolean;
+		
+		/** 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
+		 * @param strict Flag indicating if the JSON string needs to
+		 * 		strictly match the JSON standard or not.
+		 * @langversion ActionScript 3.0
+		 * @playerversion Flash 9.0
+		 * @tiptext
+		 */
+		public function JSONDecoder( s:String, strict:Boolean )
+		{	
+			this.strict = strict;
+			tokenizer = new JSONTokenizer( s, strict );
+			
+			nextToken();
+			value = parseValue();
+			
+			// Make sure the input stream is empty
+			if ( strict && nextToken() != null )
+			{
+				tokenizer.parseError( "Unexpected characters left in input stream" );
+			}
+		}
+		
+		/**
+		 * 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;
+			}
+			// in non-strict mode an empty array is also a comma
+			// followed by a right bracket
+			else if ( !strict && token.type == JSONTokenType.COMMA )
+			{
+				// move past the comma
+				nextToken();
+				
+				// check to see if we're reached the end of the array
+				if ( token.type == JSONTokenType.RIGHT_BRACKET )
+				{
+					return a;	
+				}
+				else
+				{
+					tokenizer.parseError( "Leading commas are not supported.  Expecting ']' but found " + token.value );
+				}
+			}
+			
+			// 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();
+					
+					// Allow arrays to have a comma after the last element
+					// if the decoder is not in strict mode
+					if ( !strict )
+					{
+						// Reached ",]" as the end of the array, so return it
+						if ( token.type == JSONTokenType.RIGHT_BRACKET )
+						{
+							return a;
+						}
+					}
+				}
+				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;
+			}
+			// in non-strict mode an empty object is also a comma
+			// followed by a right bracket
+			else if ( !strict && token.type == JSONTokenType.COMMA )
+			{
+				// move past the comma
+				nextToken();
+				
+				// check to see if we're reached the end of the object
+				if ( token.type == JSONTokenType.RIGHT_BRACE )
+				{
+					return o;
+				}
+				else
+				{
+					tokenizer.parseError( "Leading commas are not supported.  Expecting '}' but found " + token.value );
+				}
+			}
+			
+			// 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();
+							
+							// Allow objects to have a comma after the last member
+							// if the decoder is not in strict mode
+							if ( !strict )
+							{
+								// Reached ",}" as the end of the object, so return it
+								if ( token.type == JSONTokenType.RIGHT_BRACE )
+								{
+									return o;
+								}
+							}
+						}
+						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;
+					
+				case JSONTokenType.NAN:
+					if ( !strict )
+					{
+						return token.value;
+					}
+					else
+					{
+						tokenizer.parseError( "Unexpected " + token.value );
+					}
+
+				default:
+					tokenizer.parseError( "Unexpected " + token.value );
+					
+			}
+			
+            return null;
+		}
+	}
+}