SwapFlashLoan
Swap - A StableSwap implementation in solidity.
This contract is responsible for custody of closely pegged assets (eg. group of stablecoins) and automatic market making system. Users become an LP (Liquidity Provider) by depositing their tokens in desired ratios for an exchange of the pool token that represents their share of the pool. Users can burn pool tokens and withdraw their share of token(s). Each time a swap between the pooled tokens happens, a set fee incurs which effectively gets distributed to the LPs. In case of emergencies, admin can pause additional deposits, swaps, or single-asset withdraws - which stops the ratio of the tokens in the pool from changing. Users can always withdraw their tokens via multi-asset withdraws.
Most of the logic is stored as a library
SwapUtils for the sake of reducing contract's deployment size.function MAX_BPS() external view returns (uint256)
Name | Type | Description |
|---|---|---|
_0 | uint256 | undefined |
function addLiquidity(uint256[] amounts, uint256 minToMint, uint256 deadline) external nonpayable returns (uint256)
Add liquidity to the pool with the given amounts of tokens
Name | Type | Description |
|---|---|---|
amounts | uint256[] | the amounts of each token to add, in their native precision |
minToMint | uint256 | the minimum LP tokens adding this amount of liquidity should mint, otherwise revert. Handy for front-running mitigation |
deadline | uint256 | latest timestamp to accept this transaction |
Name | Type | Description |
|---|---|---|
_0 | uint256 | amount of LP token user minted and received |
function calculateRemoveLiquidity(uint256 amount) external view returns (uint256[])
A simple method to calculate amount of each underlying tokens that is returned upon burning given amount of LP tokens
Name | Type | Description |
|---|---|---|
amount | uint256 | the amount of LP tokens that would be burned on withdrawal |
Name | Type | Description |
|---|---|---|
_0 | uint256[] | array of token balances that the user will receive |
function calculateRemoveLiquidityOneToken(uint256 tokenAmount, uint8 tokenIndex) external view returns (uint256 availableTokenAmount)
Calculate the amount of underlying token available to withdraw when withdrawing via only single token
Name | Type | Description |
|---|---|---|
tokenAmount | uint256 | the amount of LP token to burn |
tokenIndex | uint8 | index of which token will be withdrawn |
Name | Type | Description |
|---|---|---|
availableTokenAmount | uint256 | calculated amount of underlying token available to withdraw |
function calculateSwap(uint8 tokenIndexFrom, uint8 tokenIndexTo, uint256 dx) external view returns (uint256)
Calculate amount of tokens you receive on swap
Name | Type | Description |
|---|---|---|
tokenIndexFrom | uint8 | the token the user wants to sell |
tokenIndexTo | uint8 | the token the user wants to buy |
dx | uint256 | the amount of tokens the user wants to sell. If the token charges a fee on transfers, use the amount that gets transferred after the fee. |
Name | Type | Description |
|---|---|---|
_0 | uint256 | amount of tokens the user will receive |
function calculateTokenAmount(uint256[] amounts, bool deposit) external view returns (uint256)
A simple method to calculate prices from deposits or withdrawals, excluding fees but including slippage. This is helpful as an input into the various "min" parameters on calls to fight front-running
This shouldn't be used outside frontends for user estimates.
Name | Type | Description |
|---|---|---|
amounts | uint256[] | an array of token amounts to deposit or withdrawal, corresponding to pooledTokens. The amount should be in each pooled token's native precision. If a token charges a fee on transfers, use the amount that gets transferred after the fee. |
deposit | bool | whether this is a deposit or a withdrawal |
Name | Type | Description |
|---|---|---|
_0 | uint256 | token amount the user will receive |
function flashLoan(address receiver, contract IERC20 token, uint256 amount, bytes params) external nonpayable
Borrow the specified token from this pool for this transaction only. This function will call
IFlashLoanReceiver(receiver).executeOperation and the receiver must return the full amount of the token and the associated fee by the end of the callback transaction. If the conditions are not met, this call is reverted.Name | Type | Description |
|---|---|---|
receiver | address | the address of the receiver of the token. This address must implement the IFlashLoanReceiver interface and the callback function executeOperation. |
token | contract IERC20 | the protocol fee in bps to be applied on the total flash loan fee |
amount | uint256 | the total amount to borrow in this transaction |
params | bytes | optional data to pass along to the callback function |
function flashLoanFeeBPS() external view returns (uint256)
Name | Type | Description |
|---|---|---|
_0 | uint256 | undefined |
function getA() external view returns (uint256)
Return A, the amplification coefficient * n * (n - 1)
See the StableSwap paper for details
Name | Type | Description |
|---|---|---|
_0 | uint256 | A parameter |
function getAPrecise() external view returns (uint256)
Return A in its raw precision form
See the StableSwap paper for details
Name | Type | Description |
|---|---|---|
_0 | uint256 | A parameter in its raw precision form |
function getAdminBalance(uint256 index) external view returns (uint256)
This function reads the accumulated amount of admin fees of the token with given index
Name | Type | Description |
|---|---|---|
index | uint256 | Index of the pooled token |
Name | Type | Description |
|---|---|---|
_0 | uint256 | admin's token balance in the token's precision |
function getToken(uint8 index) external view returns (contract IERC20)
Return address of the pooled token at given index. Reverts if tokenIndex is out of range.
Name | Type | Description |
|---|---|---|
index | uint8 | the index of the token |
Name | Type | Description |
|---|---|---|
_0 | contract IERC20 | address of the token at given index |
function getTokenBalance(uint8 index) external view returns (uint256)
Return current balance of the pooled token at given index
Name | Type | Description |
|---|---|---|
index | uint8 | the index of the token |
Name | Type | Description |
|---|---|---|
_0 | uint256 | current balance of the pooled token at given index with token's native precision |
function getTokenIndex(address tokenAddress) external view returns (uint8)
Return the index of the given token address. Reverts if no matching token is found.
Name | Type | Description |
|---|---|---|
tokenAddress | address | address of the token |
Name | Type | Description |
|---|---|---|
_0 | uint8 | the index of the given token address |
function getVirtualPrice() external view returns (uint256)
Get the virtual price, to help calculate profit
Name | Type | Description |
|---|---|---|
_0 | uint256 | the virtual price, scaled to the POOL_PRECISION_DECIMALS |
function initialize(contract IERC20[] _pooledTokens, uint8[] decimals, string lpTokenName, string lpTokenSymbol, uint256 _a, uint256 _fee, uint256 _adminFee, address lpTokenTargetAddress) external nonpayable
Initializes this Swap contract with the given parameters. This will also clone a LPToken contract that represents users' LP positions. The owner of LPToken will be this contract - which means only this contract is allowed to mint/burn tokens.
Name | Type | Description |
|---|---|---|
_pooledTokens | contract IERC20[] | an array of ERC20s this pool will accept |
decimals | uint8[] | the decimals to use for each pooled token, eg 8 for WBTC. Cannot be larger than POOL_PRECISION_DECIMALS |
lpTokenName | string | the long-form name of the token to be deployed |
lpTokenSymbol | string | the short symbol for the token to be deployed |
_a | uint256 | the amplification coefficient * n * (n - 1). See the StableSwap paper for details |
_fee | uint256 | default swap fee to be initialized with |
_adminFee | uint256 | default adminFee to be initialized with |
lpTokenTargetAddress | address | the address of an existing LPToken contract to use as a target |
function owner() external view returns (address)
Returns the address of the current owner.
Name | Type | Description |
|---|---|---|
_0 | address | undefined |
function pause() external nonpayable
Pause the contract. Revert if already paused.
function paused() external view returns (bool)
Returns true if the contract is paused, and false otherwise.
Name | Type | Description |
|---|---|---|
_0 | bool | undefined |
function protocolFeeShareBPS() external view returns (uint256)
Name | Type | Description |
|---|---|---|
_0 | uint256 | undefined |
function rampA(uint256 futureA, uint256 futureTime) external nonpayable
Start ramping up or down A parameter towards given futureA and futureTime Checks if the change is too rapid, and commits the new A value only when it falls under the limit range.
Name | Type | Description |
|---|---|---|
futureA | uint256 | the new A to ramp towards |
futureTime | uint256 | timestamp when the new A should be reached |
function removeLiquidity(uint256 amount, uint256[] minAmounts, uint256 deadline) external nonpayable returns (uint256[])
Burn LP tokens to remove liquidity from the pool. Withdraw fee that decays linearly over period of 4 weeks since last deposit will apply.
Liquidity can always be removed, even when the pool is paused.
Name | Type | Description |
|---|---|---|
amount | uint256 | the amount of LP tokens to burn |
minAmounts | uint256[] | the minimum amounts of each token in the pool acceptable for this burn. Useful as a front-running mitigation |
deadline | uint256 | latest timestamp to accept this transaction |
Name | Type | Description |
|---|---|---|
_0 | uint256[] | amounts of tokens user received |
function removeLiquidityImbalance(uint256[] amounts, uint256 maxBurnAmount, uint256 deadline) external nonpayable returns (uint256)
Remove liquidity from the pool, weighted differently than the pool's current balances. Withdraw fee that decays linearly over period of 4 weeks since last deposit will apply.
Name | Type | Description |
|---|---|---|
amounts | uint256[] | how much of each token to withdraw |
maxBurnAmount | uint256 | the max LP token provider is willing to pay to remove liquidity. Useful as a front-running mitigation. |
deadline | uint256 | latest timestamp to accept this transaction |
Name | Type | Description |
|---|---|---|
_0 | uint256 | amount of LP tokens burned |
function removeLiquidityOneToken(uint256 tokenAmount, uint8 tokenIndex, uint256 minAmount, uint256 deadline) external nonpayable returns (uint256)
Remove liquidity from the pool all in one token. Withdraw fee that decays linearly over period of 4 weeks since last deposit will apply.
Name | Type | Description |
|---|---|---|
tokenAmount | uint256 | the amount of the token you want to receive |
tokenIndex | uint8 | the index of the token you want to receive |
minAmount | uint256 | the minimum amount to withdraw, otherwise revert |
deadline | uint256 | latest timestamp to accept this transaction |
Name | Type | Description |
|---|---|---|
_0 | uint256 | amount of chosen token user received |
function renounceOwnership() external nonpayable
Leaves the contract without owner. It will not be possible to call
onlyOwner functions anymore. Can only be called by the current owner. NOTE: Renouncing ownership will leave the contract without an owner, thereby removing any functionality that is only available to the owner.function setAdminFee(uint256 newAdminFee) external nonpayable
Update the admin fee. Admin fee takes portion of the swap fee.
Name | Type | Description |
|---|---|---|
newAdminFee | uint256 | new admin fee to be applied on future transactions |
function setFlashLoanFees(uint256 newFlashLoanFeeBPS, uint256 newProtocolFeeShareBPS) external nonpayable
Updates the flash loan fee parameters. This function can only be called by the owner.
Name | Type | Description |
|---|---|---|
newFlashLoanFeeBPS | uint256 | the total fee in bps to be applied on future flash loans |
newProtocolFeeShareBPS | uint256 | the protocol fee in bps to be applied on the total flash loan fee |
function setSwapFee(uint256 newSwapFee) external nonpayable
Update the swap fee to be applied on swaps
Name | Type | Description |
|---|---|---|
newSwapFee | uint256 | new swap fee to be applied on future transactions |
function stopRampA() external nonpayable
Stop ramping A immediately. Reverts if ramp A is already stopped.
function swap(uint8 tokenIndexFrom, uint8 tokenIndexTo, uint256 dx, uint256 minDy, uint256 deadline) external nonpayable returns (uint256)
Swap two tokens using this pool
Name | Type | Description |
|---|---|---|
tokenIndexFrom | uint8 | the token the user wants to swap from |
tokenIndexTo | uint8 | the token the user wants to swap to |
dx | uint256 | the amount of tokens the user wants to swap from |
minDy | uint256 | the min amount the user would like to receive, or revert. |
deadline | uint256 | latest timestamp to accept this transaction |
Name | Type | Description |
|---|---|---|
_0 | uint256 | undefined |
function swapStorage() external view returns (uint256 initialA, uint256 futureA, uint256 initialATime, uint256 futureATime, uint256 swapFee, uint256 adminFee, contract LPToken lpToken)
Name | Type | Description |
|---|---|---|
initialA | uint256 | undefined |
futureA | uint256 | undefined |
initialATime | uint256 | undefined |
futureATime | uint256 | undefined |
swapFee | uint256 | undefined |
adminFee | uint256 | undefined |
lpToken | contract LPToken | undefined |
function transferOwnership(address newOwner) external nonpayable
Transfers ownership of the contract to a new account (
newOwner). Can only be called by the current owner.Name | Type | Description |
|---|---|---|
newOwner | address | undefined |
function unpause() external nonpayable
Unpause the contract. Revert if already unpaused.
function withdrawAdminFees() external nonpayable
Withdraw all admin fees to the contract owner
event AddLiquidity(address indexed provider, uint256[] tokenAmounts, uint256[] fees, uint256 invariant, uint256 lpTokenSupply)
Name | Type | Description |
|---|---|---|
provider indexed | address | undefined |
tokenAmounts | uint256[] | undefined |
fees | uint256[] | undefined |