Stableswap
This section contains a full API reference of all public functions & events related to Connext's stableswap contracts.
Events
TokenSwap
event TokenSwap(bytes32 key, address buyer, uint256 tokensSold, uint256 tokensBought, uint128 soldId, uint128 boughtId)
AddLiquidity
event AddLiquidity(bytes32 key, address provider, uint256[] tokenAmounts, uint256[] fees, uint256 invariant, uint256 lpTokenSupply)
RemoveLiquidity
event RemoveLiquidity(bytes32 key, address provider, uint256[] tokenAmounts, uint256 lpTokenSupply)
RemoveLiquidityOne
event RemoveLiquidityOne(bytes32 key, address provider, uint256 lpTokenAmount, uint256 lpTokenSupply, uint256 boughtId, uint256 tokensBought)
Getters
getSwapStorage
function getSwapStorage(bytes32 key) external view returns (struct SwapUtils.Swap)
Return Stable swap storage
Parameters
| Name | Type | Description |
|---|
| key | bytes32 | Hash of the canonical id + domain |
Return Values
| Name | Type | Description |
|---|
| [0] | struct SwapUtils.Swap | SwapUtils.Swap |
getSwapLPToken
function getSwapLPToken(bytes32 key) external view returns (address)
Return LP token for canonical Id
Parameters
| Name | Type | Description |
|---|
| key | bytes32 | Hash of the canonical id + domain |
Return Values
| Name | Type | Description |
|---|
| [0] | address | LPToken |
getSwapA
function getSwapA(bytes32 key) external view returns (uint256)
Return A, the amplification coefficient n (n - 1)
See the StableSwap paper for details
Parameters
| Name | Type | Description |
|---|
| key | bytes32 | Hash of the canonical id + domain |
Return Values
| Name | Type | Description |
|---|
| [0] | uint256 | A parameter |
getSwapAPrecise
function getSwapAPrecise(bytes32 key) external view returns (uint256)
Return A in its raw precision form
See the StableSwap paper for details
Parameters
| Name | Type | Description |
|---|
| key | bytes32 | Hash of the canonical id + domain |
Return Values
| Name | Type | Description |
|---|
| [0] | uint256 | A parameter in its raw precision form |
getSwapToken
function getSwapToken(bytes32 key, uint8 index) public view returns (contract IERC20)
Return address of the pooled token at given index. Reverts if tokenIndex is out of range.
Parameters
| Name | Type | Description |
|---|
| key | bytes32 | Hash of the canonical id + domain |
| index | uint8 | the index of the token |
Return Values
| Name | Type | Description |
|---|
| [0] | contract IERC20 | address of the token at given index |
getSwapTokenIndex
function getSwapTokenIndex(bytes32 key, address tokenAddress) public view returns (uint8)
Return the index of the given token address. Reverts if no matching
token is found.
Parameters
| Name | Type | Description |
|---|
| key | bytes32 | Hash of the canonical id + domain |
| tokenAddress | address | address of the token |
Return Values
| Name | Type | Description |
|---|
| [0] | uint8 | the index of the given token address |
getSwapTokenBalance
function getSwapTokenBalance(bytes32 key, uint8 index) external view returns (uint256)
Return current balance of the pooled token at given index
Parameters
| Name | Type | Description |
|---|
| key | bytes32 | Hash of the canonical id + domain |
| index | uint8 | the index of the token |
Return Values
| Name | Type | Description |
|---|
| [0] | uint256 | current balance of the pooled token at given index with token's native precision |
getSwapVirtualPrice
function getSwapVirtualPrice(bytes32 key) external view returns (uint256)
Get the virtual price, to help calculate profit
Parameters
| Name | Type | Description |
|---|
| key | bytes32 | Hash of the canonical id + domain |
Return Values
| Name | Type | Description |
|---|
| [0] | uint256 | the virtual price, scaled to the POOL_PRECISION_DECIMALS |
calculateSwap
function calculateSwap(bytes32 key, uint8 tokenIndexFrom, uint8 tokenIndexTo, uint256 dx) external view returns (uint256)
Calculate amount of tokens you receive on swap
Parameters
| Name | Type | Description |
|---|
| key | bytes32 | Hash of the canonical id + domain |
| 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. |
Return Values
| Name | Type | Description |
|---|
| [0] | uint256 | amount of tokens the user will receive |
calculateSwapTokenAmount
function calculateSwapTokenAmount(bytes32 key, 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.
Parameters
| Name | Type | Description |
|---|
| key | bytes32 | Hash of the canonical id + domain |
| 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 |
Return Values
| Name | Type | Description |
|---|
| [0] | uint256 | token amount the user will receive |
calculateRemoveSwapLiquidity
function calculateRemoveSwapLiquidity(bytes32 key, 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
Parameters
| Name | Type | Description |
|---|
| key | bytes32 | Hash of the canonical id + domain |
| amount | uint256 | the amount of LP tokens that would be burned on withdrawal |
Return Values
| Name | Type | Description |
|---|
| [0] | uint256[] | array of token balances that the user will receive |
calculateRemoveSwapLiquidityOneToken
function calculateRemoveSwapLiquidityOneToken(bytes32 key, uint256 tokenAmount, uint8 tokenIndex) external view returns (uint256 availableTokenAmount)
Calculate the amount of underlying token available to withdraw
when withdrawing via only single token
Parameters
| Name | Type | Description |
|---|
| key | bytes32 | Hash of the canonical id + domain |
| tokenAmount | uint256 | the amount of LP token to burn |
| tokenIndex | uint8 | index of which token will be withdrawn |
Return Values
| Name | Type | Description |
|---|
| availableTokenAmount | uint256 | calculated amount of underlying token available to withdraw |
Functions
swap
function swap(bytes32 key, uint8 tokenIndexFrom, uint8 tokenIndexTo, uint256 dx, uint256 minDy, uint256 deadline) external returns (uint256)
Swap two tokens using this pool
Parameters
| Name | Type | Description |
|---|
| key | bytes32 | Hash of the canonical id + domain |
| 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 |
swapExact
function swapExact(bytes32 key, uint256 amountIn, address assetIn, address assetOut, uint256 minAmountOut, uint256 deadline) external returns (uint256)
Swap two tokens using this pool
Parameters
| Name | Type | Description |
|---|
| key | bytes32 | Hash of the canonical id + domain |
| amountIn | uint256 | the amount of tokens the user wants to swap from |
| assetIn | address | the token the user wants to swap from |
| assetOut | address | the token the user wants to swap to |
| minAmountOut | uint256 | |
| deadline | uint256 | |
swapExactOut
function swapExactOut(bytes32 key, uint256 amountOut, address assetIn, address assetOut, uint256 maxAmountIn, uint256 deadline) external returns (uint256)
Swap two tokens using this pool
Parameters
| Name | Type | Description |
|---|
| key | bytes32 | Hash of the canonical id + domain |
| amountOut | uint256 | the amount of tokens the user wants to swap to |
| assetIn | address | the token the user wants to swap from |
| assetOut | address | the token the user wants to swap to |
| maxAmountIn | uint256 | |
| deadline | uint256 | |
addSwapLiquidity
function addSwapLiquidity(bytes32 key, uint256[] amounts, uint256 minToMint, uint256 deadline) external returns (uint256)
Add liquidity to the pool with the given amounts of tokens
Parameters
| Name | Type | Description |
|---|
| key | bytes32 | Hash of the canonical id + domain |
| 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 |
Return Values
| Name | Type | Description |
|---|
| [0] | uint256 | amount of LP token user minted and received |
removeSwapLiquidity
function removeSwapLiquidity(bytes32 key, uint256 amount, uint256[] minAmounts, uint256 deadline) external 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.
Parameters
| Name | Type | Description |
|---|
| key | bytes32 | Hash of the canonical id + domain |
| 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 |
Return Values
| Name | Type | Description |
|---|
| [0] | uint256[] | amounts of tokens user received |
removeSwapLiquidityOneToken
function removeSwapLiquidityOneToken(bytes32 key, uint256 tokenAmount, uint8 tokenIndex, uint256 minAmount, uint256 deadline) external 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.
Parameters
| Name | Type | Description |
|---|
| key | bytes32 | Hash of the canonical id + domain |
| 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 |
Return Values
| Name | Type | Description |
|---|
| [0] | uint256 | amount of chosen token user received |