Impact Contract

The CrocImpact contract provides a convenient way to calculate the price impact and resulting token flows associated with a hypothetical swap on the BEX DEX.

The contract is deployed at

Testnet: 0xCfEa3579a06e2e9a596D311486D12B3a49a919Cd

Note that calling this contract does not execute an actual swap. It simply returns the token quantities that would be paid or received if a swap were to be executed at the current chain state. When calculating off-chain, keep in mind that the state of the curve may change between the time the function is called and the time the actual swap transaction executes on-chain.

The contract has a single public method:

function calcImpact(
    address base,
    address quote,
    uint256 poolIdx,
    bool isBuy,
    bool inBaseQty,
    uint128 qty,
    uint16 tip,
    uint128 limitPrice
) public view returns (int128 baseFlow, int128 quoteFlow, uint128 finalPrice)

Parameters

Parameter	Type	Description
base	address	The address of the base token
quote	address	The address of the quote token
poolIdx	uint256	The pool type index
isBuy	bool	True if the user wants to pay base token and receive quote token. False if the user wants to receive base token and pay quote token
inBaseQty	bool	If true, the qty parameter is denominated in base tokens. If false, it's denominated in quote tokens.
qty	uint128	The quantity of tokens to swap.
tip	uint16	If zero, the user accepts the standard swap fee rate in the pool. If non-zero, the user agrees to pay up to this swap fee rate to the pool's LPs. In standard cases, this should be 0.
limitPrice	uint128	Represents the worse possible price the user is willing to accept. If buying this represents an upper bound.

Returns

Return Value	Type	Description
baseFlow	int128	The base side token flows the swap would pay/receive to the caller. A negative quantity indicates a credit received by the user from the pool, while a positive quantity indicates a debit paid to the pool by the user.
quoteFlow	int128	The quote side token flows the swap would pay/receive to the caller. The same negative/positive convention as the baseFlow return value applies.
finalPrice	uint128	The final price the pool would arrive at after the swap is executed. Note that this is the post-swap pool price, not the realized price the swapper pays. The latter can be calculated by dividing the base and quote token flows from above.