<?php
/**
 * Zend Framework
 *
 * LICENSE
 *
 * This source file is subject to the new BSD license that is bundled
 * with this package in the file LICENSE.txt.
 * It is also available through the world-wide-web at this URL:
 * http://framework.zend.com/license/new-bsd
 * If you did not receive a copy of the license and are unable to
 * obtain it through the world-wide-web, please send an email
 * to license@zend.com so we can send you a copy immediately.
 *
 * @category   Zend
 * @package    Zend_Json
 * @copyright  Copyright (c) 2006 Zend Technologies USA Inc. (http://www.zend.com)
 * @license    http://framework.zend.com/license/new-bsd     New BSD License
 */


/**
 * Zend
 */
require_once 'Zend.php';

/**
 * Zend_Json
 */
require_once 'Zend/Json.php';

/**
 * Zend_Json_Exception
 */
require_once 'Zend/Json/Exception.php';


/**
 * Decode JSON encoded string to PHP variable constructs
 *
 * @category   Zend
 * @package    Zend_Json
 * @copyright  Copyright (c) 2006 Zend Technologies USA Inc. (http://www.zend.com)
 * @license    http://framework.zend.com/license/new-bsd     New BSD License
 */
class Zend_Json_Decoder
{
    /**
     * Parse tokens used to decode the JSON object. These are not
     * for public consumption, they are just used internally to the
     * class.
     */
    const EOF	 	= 0;
    const DATUM		= 1;
    const LBRACE	= 2;
    const LBRACKET	= 3;
    const RBRACE 	= 4;
    const RBRACKET	= 5;
    const COMMA   	= 6;
    const COLON		= 7;

    /**
     * Use to maintain a "pointer" to the source being decoded
     *
     * @var string
     */
    protected $_source;

    /**
     * Caches the source length
     *
     * @var int
     */
    protected $_sourceLength;

    /**
     * The offset within the souce being decoded
     *
     * @var int
     *
     */
    protected $_offset;

    /**
     * The current token being considered in the parser cycle
     *
     * @var int
     */
    protected $_token;

    /**
     * Flag indicating how objects should be decoded
     *
     * @var int
     * @access protected
     */
    protected $_decodeType;

    /**
     * Constructor
     *
     * @param string $source String source to decode
     * @param int $decodeType How objects should be decoded -- see
     * {@link Zend_Json::TYPE_ARRAY} and {@link Zend_Json::TYPE_OBJECT} for
     * valid values
     * @return void
     */
    protected function __construct($source, $decodeType)
    {
        // Set defaults
        $this->_source       = $source;
        $this->_sourceLength = strlen($source);
    	$this->_token        = self::EOF;
    	$this->_offset       = 0;

        // Normalize and set $decodeType
        if (!in_array($decodeType, array(Zend_Json::TYPE_ARRAY, Zend_Json::TYPE_OBJECT)))
        {
            $decodeType = Zend_Json::TYPE_ARRAY;
        }
        $this->_decodeType   = $decodeType;

        // Set pointer at first token
    	$this->_getNextToken();
    }

    /**
     * Decode a JSON source string
     *
     * Decodes a JSON encoded string. The value returned will be one of the
     * following:
     *	    - integer
     *	    - float
     *	    - boolean
     *	    - null
     *      - StdClass
     *      - array
     * 	    - array of one or more of the above types
     *
     * By default, decoded objects will be returned as associative arrays; to
     * return a StdClass object instead, pass {@link Zend_Json::TYPE_OBJECT} to
     * the $objectDecodeType parameter.
     *
     * Throws a Zend_Json_Exception if the source string is null.
     *
     * @static
     * @access public
     * @param string $source String to be decoded
     * @param int $objectDecodeType How objects should be decoded; should be
     * either or {@link Zend_Json::TYPE_ARRAY} or 
     * {@link Zend_Json::TYPE_OBJECT}; defaults to TYPE_ARRAY
     * @return mixed
     * @throws Zend_Json_Exception
     */
    public static function decode($source = null, $objectDecodeType = Zend_Json::TYPE_ARRAY)
    {
        if (null === $source) {
            throw new Zend_Json_Exception('Must specify JSON encoded source for decoding');
        } elseif (!is_string($source)) {
            throw new Zend_Json_Exception('Can only decode JSON encoded strings');
        }

        $decoder = new self($source, $objectDecodeType);

    	return $decoder->_decodeValue();
    }


    /**
     * Recursive driving rountine for supported toplevel tops
     *
     * @return mixed
     */
    protected function _decodeValue()
    {
    	switch ($this->_token) {
        	case self::DATUM:
        	    $result  = $this->_tokenValue;
        	    $this->_getNextToken();
        	    return($result);
                break;
        	case self::LBRACE:
        	    return($this->_decodeObject());
                break;
        	case self::LBRACKET:
        	    return($this->_decodeArray());
                break;
            default:
                return null;
                break;
    	}
    }

    /**
     * Decodes an object of the form:
     *  { "attribute: value, "attribute2" : value,...}
     *
     * If ZJsonEnoder or ZJAjax was used to encode the original object
     * then a special attribute called __className which specifies a class
     * name that should wrap the data contained within the encoded source.
     *
     * Decodes to either an array or StdClass object, based on the value of
     * {@link $_decodeType}. If invalid $_decodeType present, returns as an
     * array.
     *
     * @return array|StdClass
     */
    protected function _decodeObject()
    {
    	$members = array();
    	$tok = $this->_getNextToken();

    	while ($tok && $tok != self::RBRACE) {
    	    if ($tok != self::DATUM || ! is_string($this->_tokenValue)) {
        		throw new Zend_Json_Exception('Missing key in object encoding: ' . $this->_source);
    	    }

    	    $key = $this->_tokenValue;
    	    $tok = $this->_getNextToken();

    	    if ($tok != self::COLON) {
        		throw new Zend_Json_Exception('Missing ":" in object encoding: ' . $this->_source);
        	}

    	    $tok = $this->_getNextToken();
    	    $members[$key] = $this->_decodeValue();
    	    $tok = $this->_token;

    	    if ($tok == self::RBRACE) {
    	        break;
    	    }

    	    if ($tok != self::COMMA) {
        		throw new Zend_Json_Exception('Missing "," in object encoding: ' . $this->_source);
    	    }

    	    $tok = $this->_getNextToken();
    	}

        switch ($this->_decodeType) {
            case Zend_Json::TYPE_OBJECT:
                // Create new StdClass and populate with $members
                $result = new StdClass();
                foreach ($members as $key => $value) {
                    $result->$key = $value;
                }
                break;
            case Zend_Json::TYPE_ARRAY:
            default:
                $result = $members;
                break;
        }

        $this->_getNextToken();
        return $result;
    }

    /**
     * Decodes a JSON array format:
     *	[element, element2,...,elementN]
     *
     * @return array
     */
    protected function _decodeArray()
    {
    	$result = array();
    	$starttok = $tok = $this->_getNextToken(); // Move past the '['
    	$index  = 0;

    	while ($tok && $tok != self::RBRACKET) {
    	    $result[$index++] = $this->_decodeValue();

    	    $tok = $this->_token;

    	    if ($tok == self::RBRACKET || !$tok) {
    	        break;
    	    }

    	    if ($tok != self::COMMA) {
        		throw new Zend_Json_Exception('Missing "," in array encoding: ' . $this->_source);
    	    }

    	    $tok = $this->_getNextToken();
    	}

    	$this->_getNextToken();
    	return($result);
    }


    /**
     * Removes whitepsace characters from the source input
     */
    protected function _eatWhitespace()
    {
    	if (preg_match(
                '/([\t\b\f\n\r ])*/s',
                $this->_source,
                $matches,
                PREG_OFFSET_CAPTURE,
                $this->_offset)
            && $matches[0][1] == $this->_offset)
        {
    	    $this->_offset += strlen($matches[0][0]);
    	}
    }


    /**
     * Retrieves the next token from the source stream
     *
     * @return int Token constant value specified in class definition
     */
    protected function _getNextToken()
    {
    	$this->_token      = self::EOF;
    	$this->_tokenValue = null;
    	$this->_eatWhitespace();

    	if ($this->_offset >= $this->_sourceLength) {
    	    return(self::EOF);
        }

    	$str        = $this->_source;
    	$str_length = $this->_sourceLength;
    	$i          = $this->_offset;
    	$start      = $i;

    	switch ($str{$i}) {
        	case '{':
        	   $this->_token = self::LBRACE;
        	   break;
        	case '}':
            	$this->_token = self::RBRACE;
            	break;
        	case '[':
            	$this->_token = self::LBRACKET;
            	break;
        	case ']':
            	$this->_token = self::RBRACKET;
            	break;
        	case ',':
            	$this->_token = self::COMMA;
            	break;
        	case ':':
            	$this->_token = self::COLON;
            	break;
        	case  '"':
        	    $result = '';
        	    do {
            		$i++;
            		if ($i >= $str_length) {
            		    break;
            		}

            		$chr = $str{$i};
            		if ($chr == '\\') {
            		    $i++;
            		    if ($i >= $str_length) {
            		        break;
            		    }
            		    $chr = $str{$i};
            		    switch ($chr) {
                		    case '"' :
                    		    $result .= '"';
                    		    break;
                		    case '\\':
                    		    $result .= '\\';
                    		    break;
                		    case '/' :
                    		    $result .= '/';
                    		    break;
                		    case 'b' :
                    		    $result .= chr(8);
                    		    break;
                		    case 'f' :
                    		    $result .= chr(12);
                    		    break;
                		    case 'n' :
                    		    $result .= chr(10);
                    		    break;
                		    case 'r' :
                    		    $result .= chr(13);
                    		    break;
                		    case 't' :
                    		    $result .= chr(9);
                    		    break;
                		    default:
                    			throw new Zend_Json_Exception("Illegal escape "
                                    .  "sequence '" . $chr . "'");
                		    }
            		} elseif ($chr == '"') {
            		    break;
            		} else {
            		    $result .= $chr;
            		}
        	    } while ($i < $str_length);

        	    $this->_token = self::DATUM;
        	    //$this->_tokenValue = substr($str, $start + 1, $i - $start - 1);
        	    $this->_tokenValue = $result;
        	    break;
        	case 't':
        	    if (($i+ 3) < $str_length && substr($str, $start, 4) == "true") {
            		$this->_token = self::DATUM;
        	    }
        	    $this->_tokenValue = true;
        	    $i += 3;
        	    break;
        	case 'f':
        	    if (($i+ 4) < $str_length && substr($str, $start, 5) == "false") {
            		$this->_token = self::DATUM;
        	    }
        	    $this->_tokenValue = false;
        	    $i += 4;
        	    break;
        	case 'n':
        	    if (($i+ 3) < $str_length && substr($str, $start, 4) == "null") {
            		$this->_token = self::DATUM;
        	    }
        	    $this->_tokenValue = NULL;
        	    $i += 3;
        	    break;
    	}

    	if ($this->_token != self::EOF) {
    	    $this->_offset = $i + 1; // Consume the last token character
    	    return($this->_token);
    	}

    	$chr = $str{$i};
    	if ($chr == '-' || $chr == '.' || ($chr >= '0' && $chr <= '9')) {
    	    if (preg_match('/-?([0-9])*(\.[0-9]*)?((e|E)((-|\+)?)[0-9]+)?/s',
    			$str, $matches, PREG_OFFSET_CAPTURE, $start) && $matches[0][1] == $start) {

        		$datum = $matches[0][0];

        		if (is_numeric($datum)) {
        		    $val  = intval($datum);
        		    $fVal = floatval($datum);
        		    $this->_tokenValue = ($val == $fVal ? $val : $fVal);
        		} else {
        		    throw new Zend_Json_Exception("Illegal number format: $datum");
        		}

        		$this->_token = self::DATUM;
        		$this->_offset = $start + strlen($datum);
    	    }
    	} else {
    	    throw new Zend_Json_Exception('Illegal Token');
    	}

    	return($this->_token);
    }
}

