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DEX

Philipp Keinberger

DEX

This contract provides a decentralized exchange, where users can use any of the liquidity pools added to the exchange to swap between assets. Liquidity pools can be added and removed through access-restricted functions, favourably controlled by a governor cvontract (e.g. DAO) to allow for decentralized governance of the DEX.

This contract implements the IERC20 Openzeppelin interface for the ERC20 token standard. It also implements the ILiquidityPool interface for liquidity pools stored on the exchange. This contract inherits from Openzeppelins OwnableUpgradeable contract in order to allow for owner features, while still keeping upgradeablity functionality. The DEX is designed to be deployed through a proxy to allow for future upgrades of the contract.

Methods

activateLiquidityPool

function activateLiquidityPool(address liquidityPoolAddress) external nonpayable

Function for activating an already existing liquidity pool on the DEX

This function can be used to allow previously used liquidity pools to be (re) activated on the DEX. It also allows for external liquidity pools that implement the ILiquidityPool interface to be activated on (added to) the exchange. The function can only be called by the owner and if the DEX is not CLOSED. The function will revert if any of these prerequisites is not met. This function emits the {LiquidityPoolActivated} event.

Parameters

Name Type Description
liquidityPoolAddress address is the address of the active liquidity pool

addNativeLiquidityPool

function addNativeLiquidityPool(address tokenAddress, uint16 swapFee, uint256 tokenDeposit) external payable

Function for adding a NativeLiquidityPool to the DEX

The function uses the parameters to deploy a new NativeLiquidityPool and initializes it. The new liuqidity pool is then added to the DEX. Note that already existing liquidity pools with the same parameters as an existing one may still be added to the DEX. This function reverts if the caller is not the owner, or the state of the contract is CLOSED. It also reverts if the transfer of tokenDeposit from msg.sender fails, or the approval of the new liquidity pool to transfer tokenDeposit to itself fails. This function emits the {LiquidityPoolAdded} event.

Parameters

Name Type Description
tokenAddress address is the address of the ERC20 contract
swapFee uint16 is the swapFee to be used for swapping in the pool
tokenDeposit uint256 is the amount of tokens to be used for initialization of the liquidity pool

addTokenLiquidityPool

function addTokenLiquidityPool(address xAddress, address yAddress, uint16 swapFee, uint256 xDeposit, uint256 yDeposit) external nonpayable

Function for adding a TokenLiquidityPool to the DEX

The function uses the parameters to deploy a new TokenLiquidityPool and initializes it. The new liuqidity pool is then added to the DEX. Note that already existing liquidity pools with the same parameters as an existing one may still be added to the DEX. The token addresses xAddress and yAddress may not match each other. This function reverts if the caller is not the owner, or the state of the contract is CLOSED. It also reverts if the transfer of xDeposit or yDeposit from msg.sender fails, or the approval of the new liquidity pool to transfer xDeposit or yDeposit to itself fails. This function emits the {LiquidityPoolAdded} event.

Parameters

Name Type Description
xAddress address is the address of the x token in the new pool
yAddress address is the address of the y token in the new pool
swapFee uint16 is the swapFee to be used for swapping in the new pool
xDeposit uint256 is the amount of x tokens to be used of the caller for initialization of the pool
yDeposit uint256 is the amount of y tokens to be used of the caller for initialization of the pool

getState

function getState() external view returns (enum DEX.State)

Function for retrieving the current State of the DEX

Returns

Name Type Description
_0 enum DEX.State State of the DEX

getStatus

function getStatus(address liquidityPoolAddress) external view returns (bool)

Function for retrieving activation status of liquidity pool at liquidityPoolAddress

Parameters

Name Type Description
liquidityPoolAddress address is the address of the liquidity pool

Returns

Name Type Description
_0 bool Activation value of liquidity pool at liquidityPoolAddress

getVersion

function getVersion() external pure returns (uint256)

Function for retrieving version of the DEX

Returns

Name Type Description
_0 uint256 Version

initialize

function initialize() external nonpayable

Initializer function which replaces constructor for upgradeability functionality. Sets msg.sender as owner of the contract

owner

function owner() external view returns (address)

Returns the address of the current owner.

Returns

Name Type Description
_0 address undefined

removeLiquidityPool

function removeLiquidityPool(address liquidityPoolAddress) external nonpayable

Function for removing a liquidity pool

The function can only be called by the owner, if the DEX is not CLOSED and the liquidity pool exists on the DEX. The function will revert if any of these prerequisites is not met. This function emits the {LiquidityPoolRemoved} event.

Parameters

Name Type Description
liquidityPoolAddress address is the address of the liquidity pool

renounceOwnership

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.

setState

function setState(enum DEX.State newState) external nonpayable

Function for setting the state of the DEX

This function can only be called by the owner. This function emits the {StateUpdated} event

Parameters

Name Type Description
newState enum DEX.State is the new state value of the contract

swapAt

function swapAt(address liquidityPoolAddress, uint256 tokenAmount) external payable

Function for swapping at liquidity pool at liquidityPoolAddress

The function calls the swapFrom function of the liquidity pool at liquidityPoolAddress (see ILiquidityPool for more documentation). In order for the DEX to be able to swap from the caller (swap on behalf of msg.sender), the DEX needs to be approved with the tokenAmount or msg.value (depending on the pool and swap direction) by the caller at the liquidity pool prior to calling this function. See approve at ILiquidityPool for more documentation. The function can only be called if the DEX is not CLOSED. This implemenation will check for the liquidity pool at liquidityPoolAddress being active. The function will revert if any of these prerequisites is not met.

Parameters

Name Type Description
liquidityPoolAddress address is the address of the liquidity pool
tokenAmount uint256 is the amount of tokens to be swapped. Note that tokenAmount can be zero if swapping native for tokens (xToY, NativeLiquidityPool)

transferOwnership

function transferOwnership(address newOwner) external nonpayable

Transfers ownership of the contract to a new account (newOwner). Can only be called by the current owner.

Parameters

Name Type Description
newOwner address undefined

Events

Initialized

event Initialized(uint8 version)

Parameters

Name Type Description
version uint8 undefined

LiquidityPoolActivated

event LiquidityPoolActivated(address liquidityPoolAddress)

Event emitted when an already existing liquidity pool is activated on the DEX

Parameters

Name Type Description
liquidityPoolAddress address undefined

LiquidityPoolAdded

event LiquidityPoolAdded(address liquidityPoolAddress, enum ILiquidityPool.Kind liquidityPoolKind)

Event emitted when a new liquidity pool is added to the pool

Parameters

Name Type Description
liquidityPoolAddress address undefined
liquidityPoolKind enum ILiquidityPool.Kind undefined

LiquidityPoolRemoved

event LiquidityPoolRemoved(address liquidityPoolAddress)

Event emitted when a liquidity pool is removed from the DEX

Parameters

Name Type Description
liquidityPoolAddress address undefined

OwnershipTransferred

event OwnershipTransferred(address indexed previousOwner, address indexed newOwner)

Parameters

Name Type Description
previousOwner indexed address undefined
newOwner indexed address undefined

StateUpdated

event StateUpdated(enum DEX.State newState)

Event emitted when the state of the contract gets updated

Parameters

Name Type Description
newState enum DEX.State undefined

Errors

DEX__LiquidityPoolIsActive

error DEX__LiquidityPoolIsActive(address liquidityPoolAddress)

Thrown when liquidity pool at liquidityPoolAddress is already activated

Parameters

Name Type Description
liquidityPoolAddress address undefined

DEX__LiquidityPoolNotActive

error DEX__LiquidityPoolNotActive(address liquidityPoolAddress)

Thrown when liquidityPoolAddress is not an active liquidity pool

Parameters

Name Type Description
liquidityPoolAddress address undefined

DEX__StateIs

error DEX__StateIs(uint8 state)

Thrown when state of contract is not equal to state

Parameters

Name Type Description
state uint8 undefined

DEX__StateIsNot

error DEX__StateIsNot(uint8 state)

Thrown when state of contract is equal to state

Parameters

Name Type Description
state uint8 undefined

DEX__TokenAddressesOfTokenLiquidityPoolMatching

error DEX__TokenAddressesOfTokenLiquidityPoolMatching()

Thrown when x and y addresses of new TokenLiquidityPool match

DEX__TokenApprovalFailed

error DEX__TokenApprovalFailed(address tokenAddress)

Thrown when approve function of ERC20 at tokenAddress fails

Parameters

Name Type Description
tokenAddress address undefined

DEX__TokenTransferFailed

error DEX__TokenTransferFailed(address tokenAddress)

Thrown when transfer of tokens at ERC20 tokenAddress fails

Parameters

Name Type Description
tokenAddress address undefined