MetaSwapDeposit

This contract flattens the LP token in a MetaSwap pool for easier user access. MetaSwap must be deployed before this contract can be initialized successfully.

For example, suppose there exists a base Swap pool consisting of [DAI, USDC, USDT]. Then a MetaSwap pool can be created with [sUSD, BaseSwapLPToken] to allow trades between either the LP token or the underlying tokens and sUSD.

MetaSwapDeposit flattens the LP token and remaps them to a single array, allowing users to ignore the dependency on BaseSwapLPToken. Using the above example, MetaSwapDeposit can act as a Swap containing [sUSD, DAI, USDC, USDT] tokens.

Functions:

• initialize(contract ISwap _baseSwap, contract IMetaSwap _metaSwap, contract IERC20 _metaLPToken)

• swap(uint8 tokenIndexFrom, uint8 tokenIndexTo, uint256 dx, uint256 minDy, uint256 deadline)

• addLiquidity(uint256[] amounts, uint256 minToMint, uint256 deadline)

• removeLiquidity(uint256 amount, uint256[] minAmounts, uint256 deadline)

• removeLiquidityOneToken(uint256 tokenAmount, uint8 tokenIndex, uint256 minAmount, uint256 deadline)

• removeLiquidityImbalance(uint256[] amounts, uint256 maxBurnAmount, uint256 deadline)

• calculateTokenAmount(uint256[] amounts, bool deposit)

• calculateRemoveLiquidity(uint256 amount)

• calculateRemoveLiquidityOneToken(uint256 tokenAmount, uint8 tokenIndex)

• getToken(uint8 index)

• calculateSwap(uint8 tokenIndexFrom, uint8 tokenIndexTo, uint256 dx)

Function initialize(contract ISwap _baseSwap, contract IMetaSwap _metaSwap, contract IERC20 _metaLPToken)

Sets the address for the base Swap contract, MetaSwap contract, and the MetaSwap LP token contract.

Parameters:

• _baseSwap: the address of the base Swap contract

• _metaSwap: the address of the MetaSwap contract

• _metaLPToken: the address of the MetaSwap LP token contract

Function swap(uint8 tokenIndexFrom, uint8 tokenIndexTo, uint256 dx, uint256 minDy, uint256 deadline) → uint256

Swap two underlying tokens using the meta pool and the base pool

Parameters:

• tokenIndexFrom: the token the user wants to swap from

• tokenIndexTo: the token the user wants to swap to

• dx: the amount of tokens the user wants to swap from

• minDy: the min amount the user would like to receive, or revert.

• deadline: latest timestamp to accept this transaction

Function addLiquidity(uint256[] amounts, uint256 minToMint, uint256 deadline) → uint256

Add liquidity to the pool with the given amounts of tokens

Parameters:

• amounts: the amounts of each token to add, in their native precision

• minToMint: the minimum LP tokens adding this amount of liquidity should mint, otherwise revert. Handy for front-running mitigation

• deadline: latest timestamp to accept this transaction

Return Values:

• amount of LP token user minted and received

Function removeLiquidity(uint256 amount, uint256[] minAmounts, uint256 deadline) → 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:

• amount: the amount of LP tokens to burn

• minAmounts: the minimum amounts of each token in the pool acceptable for this burn. Useful as a front-running mitigation

• deadline: latest timestamp to accept this transaction

Return Values:

• amounts of tokens user received

Function removeLiquidityOneToken(uint256 tokenAmount, uint8 tokenIndex, uint256 minAmount, uint256 deadline) → 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:

• tokenAmount: the amount of the token you want to receive

• tokenIndex: the index of the token you want to receive

• minAmount: the minimum amount to withdraw, otherwise revert

• deadline: latest timestamp to accept this transaction

Return Values:

• amount of chosen token user received

Function removeLiquidityImbalance(uint256[] amounts, uint256 maxBurnAmount, uint256 deadline) → 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.

Parameters:

• amounts: how much of each token to withdraw

• maxBurnAmount: the max LP token provider is willing to pay to remove liquidity. Useful as a front-running mitigation.

• deadline: latest timestamp to accept this transaction

Return Values:

• amount of LP tokens burned

Function calculateTokenAmount(uint256[] amounts, bool deposit) → 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. When withdrawing from the base pool in imbalanced fashion, the recommended slippage setting is 0.2% or higher.

This shouldn't be used outside frontends for user estimates.

Parameters:

• amounts: 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: whether this is a deposit or a withdrawal

Return Values:

• token amount the user will receive

Function calculateRemoveLiquidity(uint256 amount) → uint256[]

A simple method to calculate amount of each underlying tokens that is returned upon burning given amount of LP tokens

Parameters:

• amount: the amount of LP tokens that would be burned on withdrawal

Return Values:

• array of token balances that the user will receive

Function calculateRemoveLiquidityOneToken(uint256 tokenAmount, uint8 tokenIndex) → uint256

Calculate the amount of underlying token available to withdraw when withdrawing via only single token

Parameters:

• tokenAmount: the amount of LP token to burn

• tokenIndex: index of which token will be withdrawn

Return Values:

• availableTokenAmount calculated amount of underlying token available to withdraw

Function getToken(uint8 index) → contract IERC20

Returns the address of the pooled token at given index. Reverts if tokenIndex is out of range. This is a flattened representation of the pooled tokens.

Parameters:

• index: the index of the token

Return Values:

• address of the token at given index

Function calculateSwap(uint8 tokenIndexFrom, uint8 tokenIndexTo, uint256 dx) → uint256

Calculate amount of tokens you receive on swap

Parameters:

• tokenIndexFrom: the token the user wants to sell

• tokenIndexTo: the token the user wants to buy

• dx: 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:

• amount of tokens the user will receive