forked from Mirrors/freeswitch
328 lines
9.0 KiB
ActionScript
328 lines
9.0 KiB
ActionScript
/*
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Copyright (c) 2008, Adobe Systems Incorporated
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All rights reserved.
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions are
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met:
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* Redistributions of source code must retain the above copyright notice,
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this list of conditions and the following disclaimer.
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* Redistributions in binary form must reproduce the above copyright
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notice, this list of conditions and the following disclaimer in the
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documentation and/or other materials provided with the distribution.
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* Neither the name of Adobe Systems Incorporated nor the names of its
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contributors may be used to endorse or promote products derived from
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this software without specific prior written permission.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
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IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
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THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
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CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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package com.adobe.serialization.json
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{
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public class JSONDecoder
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{
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/**
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* Flag indicating if the parser should be strict about the format
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* of the JSON string it is attempting to decode.
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*/
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private var strict:Boolean;
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/** The value that will get parsed from the JSON string */
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private var value:*;
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/** The tokenizer designated to read the JSON string */
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private var tokenizer:JSONTokenizer;
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/** The current token from the tokenizer */
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private var token:JSONToken;
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/**
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* Constructs a new JSONDecoder to parse a JSON string
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* into a native object.
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*
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* @param s The JSON string to be converted
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* into a native object
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* @param strict Flag indicating if the JSON string needs to
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* strictly match the JSON standard or not.
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* @langversion ActionScript 3.0
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* @playerversion Flash 9.0
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* @tiptext
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*/
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public function JSONDecoder( s:String, strict:Boolean )
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{
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this.strict = strict;
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tokenizer = new JSONTokenizer( s, strict );
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nextToken();
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value = parseValue();
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// Make sure the input stream is empty
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if ( strict && nextToken() != null )
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{
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tokenizer.parseError( "Unexpected characters left in input stream" );
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}
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}
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/**
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* Gets the internal object that was created by parsing
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* the JSON string passed to the constructor.
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*
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* @return The internal object representation of the JSON
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* string that was passed to the constructor
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* @langversion ActionScript 3.0
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* @playerversion Flash 9.0
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* @tiptext
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*/
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public function getValue():*
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{
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return value;
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}
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/**
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* Returns the next token from the tokenzier reading
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* the JSON string
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*/
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private function nextToken():JSONToken
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{
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return token = tokenizer.getNextToken();
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}
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/**
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* Attempt to parse an array.
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*/
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private function parseArray():Array
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{
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// create an array internally that we're going to attempt
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// to parse from the tokenizer
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var a:Array = new Array();
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// grab the next token from the tokenizer to move
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// past the opening [
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nextToken();
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// check to see if we have an empty array
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if ( token.type == JSONTokenType.RIGHT_BRACKET )
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{
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// we're done reading the array, so return it
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return a;
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}
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// in non-strict mode an empty array is also a comma
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// followed by a right bracket
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else if ( !strict && token.type == JSONTokenType.COMMA )
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{
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// move past the comma
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nextToken();
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// check to see if we're reached the end of the array
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if ( token.type == JSONTokenType.RIGHT_BRACKET )
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{
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return a;
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}
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else
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{
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tokenizer.parseError( "Leading commas are not supported. Expecting ']' but found " + token.value );
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}
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}
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// deal with elements of the array, and use an "infinite"
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// loop because we could have any amount of elements
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while ( true )
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{
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// read in the value and add it to the array
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a.push( parseValue() );
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// after the value there should be a ] or a ,
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nextToken();
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if ( token.type == JSONTokenType.RIGHT_BRACKET )
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{
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// we're done reading the array, so return it
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return a;
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}
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else if ( token.type == JSONTokenType.COMMA )
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{
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// move past the comma and read another value
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nextToken();
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// Allow arrays to have a comma after the last element
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// if the decoder is not in strict mode
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if ( !strict )
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{
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// Reached ",]" as the end of the array, so return it
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if ( token.type == JSONTokenType.RIGHT_BRACKET )
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{
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return a;
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}
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}
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}
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else
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{
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tokenizer.parseError( "Expecting ] or , but found " + token.value );
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}
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}
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return null;
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}
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/**
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* Attempt to parse an object.
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*/
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private function parseObject():Object
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{
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// create the object internally that we're going to
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// attempt to parse from the tokenizer
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var o:Object = new Object();
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// store the string part of an object member so
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// that we can assign it a value in the object
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var key:String
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// grab the next token from the tokenizer
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nextToken();
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// check to see if we have an empty object
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if ( token.type == JSONTokenType.RIGHT_BRACE )
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{
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// we're done reading the object, so return it
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return o;
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}
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// in non-strict mode an empty object is also a comma
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// followed by a right bracket
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else if ( !strict && token.type == JSONTokenType.COMMA )
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{
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// move past the comma
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nextToken();
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// check to see if we're reached the end of the object
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if ( token.type == JSONTokenType.RIGHT_BRACE )
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{
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return o;
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}
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else
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{
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tokenizer.parseError( "Leading commas are not supported. Expecting '}' but found " + token.value );
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}
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}
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// deal with members of the object, and use an "infinite"
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// loop because we could have any amount of members
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while ( true )
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{
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if ( token.type == JSONTokenType.STRING )
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{
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// the string value we read is the key for the object
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key = String( token.value );
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// move past the string to see what's next
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nextToken();
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// after the string there should be a :
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if ( token.type == JSONTokenType.COLON )
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{
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// move past the : and read/assign a value for the key
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nextToken();
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o[key] = parseValue();
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// move past the value to see what's next
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nextToken();
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// after the value there's either a } or a ,
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if ( token.type == JSONTokenType.RIGHT_BRACE )
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{
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// we're done reading the object, so return it
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return o;
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}
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else if ( token.type == JSONTokenType.COMMA )
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{
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// skip past the comma and read another member
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nextToken();
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// Allow objects to have a comma after the last member
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// if the decoder is not in strict mode
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if ( !strict )
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{
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// Reached ",}" as the end of the object, so return it
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if ( token.type == JSONTokenType.RIGHT_BRACE )
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{
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return o;
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}
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}
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}
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else
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{
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tokenizer.parseError( "Expecting } or , but found " + token.value );
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}
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}
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else
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{
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tokenizer.parseError( "Expecting : but found " + token.value );
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}
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}
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else
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{
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tokenizer.parseError( "Expecting string but found " + token.value );
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}
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}
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return null;
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}
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/**
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* Attempt to parse a value
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*/
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private function parseValue():Object
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{
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// Catch errors when the input stream ends abruptly
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if ( token == null )
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{
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tokenizer.parseError( "Unexpected end of input" );
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}
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switch ( token.type )
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{
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case JSONTokenType.LEFT_BRACE:
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return parseObject();
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case JSONTokenType.LEFT_BRACKET:
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return parseArray();
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case JSONTokenType.STRING:
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case JSONTokenType.NUMBER:
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case JSONTokenType.TRUE:
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case JSONTokenType.FALSE:
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case JSONTokenType.NULL:
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return token.value;
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case JSONTokenType.NAN:
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if ( !strict )
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{
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return token.value;
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}
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else
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{
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tokenizer.parseError( "Unexpected " + token.value );
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}
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default:
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tokenizer.parseError( "Unexpected " + token.value );
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}
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return null;
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}
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}
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}
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