JSON PHP 完全注释（二）

来源：互联网发布：指南针软件骗局编辑：程序博客网时间：2024/06/03 20:27

/**
         * Constructor
         *
         * @param string $source String source to decode
         * @param int $decodeType How objects should be decoded -- see
         * {@link Zend_Json::TYPE_ARRAY} and {@link Zend_Json::TYPE_OBJECT} for
         * valid values
         * @return void
         */
        function decode($source) //默认入口
        {
            // Set defaults
            $this->_source       = $source;    // 保存原始字符串
            $this->_sourceLength = strlen($source);       //长度
           $this->_token        = EOF;   // 当前token
           $this->_offset       = 0;     //偏移量

            // Set pointer at first token
           $this->_getNextToken();       // 得到下一个token
           return $this->_decodeValue();   // 调用真正的decode方法
        }

        /**
         * Recursive driving rountine for supported toplevel tops
         *
         * @return mixed
         */
        function _decodeValue()
        {
           switch ($this->_token)
           {
               case DATUM:
                    $result = $this->_tokenValue;         // ？
                    $this->_getNextToken();
                    return $result;
                break;

               case LBRACE: // 左边大括号
                    return $this->_decodeObject();    // 表明是一个object，如数据库中buddylist
                break;

               case LBRACKET: //右边大括号
                    return $this->_decodeArray();
                break;

                default:   //默认 EOF，[]，；，：四类字符
                    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
         */
        function _decodeObject()
        {
           $result = array();
           $tok = $this->_getNextToken();

           while ($tok && $tok != RBRACE)    // tok!=EOF || '}'
           {

                $key = $this->_tokenValue;       // key is maybe a string for the reason of getNextToken() on coming across a "

                $this->_getNextToken();

                $tok = $this->_getNextToken();
                $result[$key] = $this->_decodeValue(); // result is a two-demension Array
                $tok = $this->_token;

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

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

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

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

           while ($tok && $tok != RBRACKET)   // tok!=EOF && tok!=']'
           {
                $result[$index++] = $this->_decodeValue(); //result is a 1-demensional Array

                $tok = $this->_token;

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

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

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