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CelerCircleBridgeFacet.md

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Celer Circle Bridge Facet

How it works

The Celer Circle Bridge Facet works by forwarding transfers to Celer's Proxy contract of the official Circle Bridge Token Messenger contract. Cross-Chain Transfer Protocol (CCTP) is a permissionless on-chain utility that can burn native USDC on a source chain, and mint native USDC of the same amount on a destination chain. The Celer Proxy takes a small fee which will be used to claim the transfer on the destination chain for the user automatically.

graph LR;
    D{LiFiDiamond}-- DELEGATECALL -->CelerCircleBridgeFacet;
    CelerCircleBridgeFacet -- CALL --> CircleBridgeProxy
    CircleBridgeProxy -- CALL --> M(Token Messenger)
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Public Methods

  • function startBridgeTokensViaCelerCircleBridge(BridgeData calldata _bridgeData)
    • Simply bridges tokens using Celer Circle Bridge
  • function swapAndStartBridgeTokensViaCelerCircleBridge(BridgeData memory _bridgeData, SwapData[] calldata _swapData)
    • Performs swap(s) before bridging tokens using Celer Circle Bridge

Swap Data

Some methods accept a SwapData _swapData parameter.

Swapping is performed by a swap specific library that expects an array of calldata to can be run on various DEXs (i.e. Uniswap) to make one or multiple swaps before performing another action.

The swap library can be found here.

LiFi Data

Some methods accept a BridgeData _bridgeData parameter.

This parameter is strictly for analytics purposes. It's used to emit events that we can later track and index in our subgraphs and provide data on how our contracts are being used. BridgeData and the events we can emit can be found here.

Getting Sample Calls to interact with the Facet

In the following some sample calls are shown that allow you to retrieve a populated transaction that can be sent to our contract via your wallet.

All examples use our /quote endpoint to retrieve a quote which contains a transactionRequest. This request can directly be sent to your wallet to trigger the transaction.

The quote result looks like the following:

const quoteResult = {
  id: '0x...', // quote id
  type: 'lifi', // the type of the quote (all lifi contract calls have the type "lifi")
  tool: 'circle', // the bridge tool used for the transaction
  action: {}, // information about what is going to happen
  estimate: {}, // information about the estimated outcome of the call
  includedSteps: [], // steps that are executed by the contract as part of this transaction, e.g. a swap step and a cross step
  transactionRequest: {
    // the transaction that can be sent using a wallet
    data: '0x...',
    to: '0x...',
    value: '0x00',
    from: '{YOUR_WALLET_ADDRESS}',
    chainId: 100,
    gasLimit: '0x...',
    gasPrice: '0x...',
  },
}

A detailed explanation on how to use the /quote endpoint and how to trigger the transaction can be found here.

Hint: Don't forget to replace {YOUR_WALLET_ADDRESS} with your real wallet address in the examples.

Cross Only

To get a transaction for a transfer from 20 USDC on Ethereum to USDC on Avalanche you can execute the following request:

curl 'https://li.quest/v1/quote?fromChain=ETH&fromAmount=20000000&fromToken=USDC&toChain=AVA&toToken=USDC&slippage=0.03&allowBridges=circle&fromAddress={YOUR_WALLET_ADDRESS}'

Swap & Cross

To get a transaction for a transfer from 10 USDT on Ethereum to USDC on Avalanche you can execute the following request:

curl 'https://li.quest/v1/quote?fromChain=ETH&fromAmount=10000000&fromToken=USDT&toChain=AVA&toToken=USDC&slippage=0.03&allowBridges=circle&fromAddress={YOUR_WALLET_ADDRESS}'