支持decode

对于数据的处理不仅支持编码（encode），还支持解码（decode）。使用exchange.IO("decode", types, rawData)函数进行解码操作。

            javascript
            
            
function main() {
    // register SwapRouter02 abi
    var walletAddress = "0x398a93ca23CBdd2642a07445bCD2b8435e0a373f"
    var routerAddress = "0x68b3465833fb72A70ecDF485E0e4C7bD8665Fc45"
    var abi = `[{"inputs":[{"components":[{"internalType":"bytes","name":"path","type":"bytes"},{"internalType":"address","name":"recipient","type":"address"},{"internalType":"uint256","name":"amountOut","type":"uint256"},{"internalType":"uint256","name":"amountInMaximum","type":"uint256"}],"internalType":"struct IV3SwapRouter.ExactOutputParams","name":"params","type":"tuple"}],"name":"exactOutput","outputs":[{"internalType":"uint256","name":"amountIn","type":"uint256"}],"stateMutability":"payable","type":"function"}]`
    exchange.IO("abi", routerAddress, abi)   // 此处ABI仅包含exactOutput方法的内容，完整的ABI可以在网上搜索获取

    // encode path
    var fee = exchange.IO("encodePacked", "uint24", 3000)
    var tokenInAddress = "0xc02aaa39b223fe8d0a0e5c4f27ead9083c756cc2"
    var tokenOutAddress = "0xdac17f958d2ee523a2206206994597c13d831ec7"
    var path = tokenInAddress.slice(2).toLowerCase()
    path += fee + tokenOutAddress.slice(2).toLowerCase()
    Log("path:", path)

    var dataTuple = {
        "path" : path,
        "recipient" : walletAddress,
        "amountOut" : 1000,
        "amountInMaximum" : 1,
    }
    // encode SwapRouter02 exactOutput
    var rawData = exchange.IO("encode", routerAddress, "exactOutput", dataTuple)
    Log("method hash:", rawData.slice(0, 8))   // 09b81346
    Log("params hash:", rawData.slice(8))

    // decode exactOutput params
    var decodeRaw = exchange.IO("decode", "tuple(path bytes,recipient address,amountOut uint256,amountInMaximum uint256)", rawData.slice(8))
    Log("decodeRaw:", decodeRaw)
}

该示例首先在处理path参数时执行了encodePacked操作，因为后续需要编码的exactOutput方法调用需要将path作为参数。然后对路由合约的exactOutput方法进行编码，该方法仅有一个参数，参数类型为tuple类型。
exactOutput方法名编码后为：0x09b81346，使用exchange.IO("decode", ...)方法解码得到的decodeRaw与变量dataTuple一致。