Improvement, add info in the SwapERC20 event to track the exchange ratio of pair.

[Jason-Zhangxin-Chen]

Hi, is it possible to add such info in the SwapERC20 event, thus that we can track the orderbooks and aggregate the exchange ratio of pairs from airswap network easily?

emit SwapERC20(nonce, signerWallet, signerToken, signerAmount, senderToken, senderAmount);

[dmosites]

Hello, this info was removed from the event log to improve gas efficiency. It can be derived from Transfer events on the same transaction, which is done for example in getFullSwapERC20 available in @airswap/utils.
https://github.com/airswap/airswap-protocols/blob/develop/tools/utils/src/swap-erc20.ts#L354

[Jason-Zhangxin-Chen]

Thank you so much, @dmosites. Just a few more questions:

• Regarding the Swap functions, are they possible to be called from other smart contract? With such scenarios, is it possible to emit multiple SwapERC20 events within a single transaction? I am just curious that if current getFullSwapERC20() can capture all the swap events in some edge cases?
• In the getFullSwapERC20, the pairing of signer and sender assumes that the msg.sender of https://github.com/airswap/airswap-protocols/blob/develop/source/swap-erc20/contracts/SwapERC20.sol#L142 equals to the recepient of https://github.com/airswap/airswap-protocols/blob/develop/source/swap-erc20/contracts/SwapERC20.sol#L151, can this assumption be always true?

[dmosites]

Thanks for following up @Jason-Zhangxin-Chen. It's possible for there to be multiple swaps and therefore multiple SwapERC20 events in the same transaction, though this is not common today. The respective Transfer events generally precede the SwapERC20 events, so we could ensure that the helper function takes that into account. As for pairing sender and recipient, the helper function would map msg.sender to recipient and should be able to do so by looking at the inputs to the function call. If this sounds right we'll take a look at making those changes. Thank you!

[Jason-Zhangxin-Chen]

@dmosites , thank you so much for the feedback. Yeah, I think as for the pairing of sender and recipient, it would be great to update the helper function, please let me know when you have this PR ready, I will also review it. Thank you in advance.