aTokens are tokens minted and burnt upon supply and withdraw of assets to an Aave market. aTokens denote the amount of crypto assets supplied to the protocol and the yield earned on those assets. The aTokens’ value is pegged to the value of the corresponding supplied asset at a 1:1 ratio and can be safely stored, transferred or traded. All yield collected by the aTokens' reserves are distributed to aToken holders directly by continuously increasing their wallet balance.

This contract is the implementation of the interest bearing token for the Aave Protocol. It inherits the ScaledBalanceTokenBase and EIP712Base token contracts.

All standard EIP20 methods are implemented for aTokens, such as balanceOf, transfer, transferFrom, approve, totalSupply etc.

balanceOf will always return the most up to date balance of the user, which includes their principal balance and the yield generated by the principal balance.

The source code is available on GitHub.

function initialize(    IPool initializingPool,    address treasury,    address underlyingAsset,    IAaveIncentivesController incentivesController,    uint8 aTokenDecimals,    string calldata aTokenName,    string calldata aTokenSymbol,    bytes calldata params) public virtual

Called when aToken instance is initialized.

function mint(    address caller,    address onBehalfOf,    uint256 amount,    uint256 index) external virtual override onlyPool returns (bool)

Mints amount aTokens to user.

function burn(    address from,    address receiverOfUnderlying,    uint256 amount,    uint256 index) external virtual override onlyPool

Burns aTokens from user and sends the equivalent amount of underlying to receiverOfUnderlying.

In some instances, the mint event could be emitted from a burn transaction if the amount to burn is less than the interest that the user accrued.

function mintToTreasury(uint256 amount, uint256 index) external override onlyPool

Mints aTokens to the reserve treasury.

function transferOnLiquidation(    address from,    address to,    uint256 value) virtual override onlyPool

Transfers aTokens in the event of a borrow being liquidated, in case the liquidator reclaims the aToken.

function transferUnderlyingTo(address target, uint256 amount) external virtual override onlyPool

Transfers the underlying asset to target.

Used by the Pool to transfer assets in borrow(), withdraw() and flashLoan().

function handleRepayment(address user, address onBehalfOf, uint256 amount) external virtual override onlyPool

Handles the underlying received by the aToken after the transfer has been completed.

The default implementation is empty as with standard ERC20 tokens, nothing needs to be done after the transfer is concluded. However in the future there may be aTokens that allow for example to stake the underlying to receive LM rewards. In that case, handleRepayment() would perform the staking of the underlying asset.

function permit(    address owner,    address spender,    uint256 value,    uint256 deadline,    uint8 v,    bytes32 r,    bytes32 s) external override

Allows a user to permit another account (or contract) to use their funds using a signed message. This enables gas-less transactions and single approval/transfer transactions. Allow passing a signed message to approve spending.

Implements the permit function as for EIP-2612.

Example of signing and utilizing permit:

import { signTypedData_v4 } from "eth-sig-util";import { fromRpcSig } from "ethereumjs-util";// ... other importsimport aTokenAbi from "./aTokenAbi.json";// ... setup your web3 providerconst aTokenAddress = "ATOKEN_ADDRESS";const aTokenContract = new web3.eth.Contract(aTokenAbi, aTokenAddress);const privateKey = "YOUR_PRIVATE_KEY_WITHOUT_0x";const chainId = 1;const owner = "OWNER_ADDRESS";const spender = "SPENDER_ADDRESS";const value = 100; // Amount the spender is permittedconst nonce = 1; // The next valid nonce, use `_nonces()`const deadline = 1600093162;const permitParams = {  types: {    EIP712Domain: [      { name: "name", type: "string" },      { name: "version", type: "string" },      { name: "chainId", type: "uint256" },      { name: "verifyingContract", type: "address" },    ],    Permit: [      { name: "owner", type: "address" },      { name: "spender", type: "address" },      { name: "value", type: "uint256" },      { name: "nonce", type: "uint256" },      { name: "deadline", type: "uint256" },    ],  },  primaryType: "Permit",  domain: {    name: "aTOKEN_NAME",    version: "1",    chainId: chainId,    verifyingContract: aTokenAddress,  },  message: {    owner,    spender,    value,    nonce,    deadline,  },};const signature = signTypedData_v4(Buffer.from(privateKey, "hex"), {  data: permitParams,});// The signature can now be used to execute the transactionconst { v, r, s } = fromRpcSig(signature);await aTokenContract.methods  .permit({    owner,    spender,    value,    deadline,    v,    r,    s,  })  .send()  .catch((e) => {    throw Error(`Error permitting: ${e.message}`);  });

function rescueTokens(    address token,    address to,    uint256 amount) external override onlyPoolAdmin

Rescue and transfer tokens locked in this contract. Only callable by POOL_ADMIN.

function balanceOf(address user)    public    view    virtual    override(IncentivizedERC20, IERC20)    returns (uint256)

Returns the amount of tokens owned by user.

Overrides the base function.

function totalSupply() public view virtual override(IncentivizedERC20, IERC20 returns (uint256)

Returns the amount of tokens in existence.

Overrides the base function.

function RESERVE_TREASURY_ADDRESS() external view override returns (address)

Returns the address of the Aave treasury, controlled by governance, receiving the fees on this aToken.

function UNDERLYING_ASSET_ADDRESS() external view override returns (address)

Returns the address of the underlying reserve asset of this aToken (E.g. WETH for aWETH).

function DOMAIN_SEPARATOR() public view override(IAToken, EIP712Base) returns (bytes32)

Get the domain separator for the token at the current chain.

Return cached value if chainId matches cache, otherwise recomputes separator.

Overrides the base function to fully implement IAToken.

function nonces(address owner) public view override(IAToken, EIP712Base) returns (uint256)

Returns the nonce value for address specified as parameter. This is the nonce used when calling permit().

Overrides the base function to fully implement IAToken.

Example:

const token = new Contract(aTokenAddress, aToken.abi, provider);await token.nonces(user);

function getRevision() internal pure virtual override returns (uint256)

Returns the revision number of the contract. Needs to be defined in the inherited class as a constant.

Returns 0x1.

The StataTokenFactory is a factory and registry contract that manages all deployed StataToken instances for a specified Aave pool. It allows deploying new StataToken instances on demand and validates that there is only one StataToken instance per underlying asset. This contract maintains a mapping between underlying assets and their corresponding StataToken addresses.

StataTokens are ERC-4626 compliant tokens that wrap Aave's aTokens to provide a non-rebasing yield accrual mechanism.

The source code is available on GitHub.

function initialize() external initializer

Initializes the StataTokenFactory contract. This function is part of the Initializable pattern and is required to initialize the contract after deployment. In this implementation, it does not perform any actions.

function createStataTokens(address[] memory underlyings) external returns (address[] memory)

Creates new StataToken instances for the given underlying assets if they do not already exist. For each provided underlying asset, the function checks if a StataToken already exists. If it does, the existing StataToken address is returned. If not, it deploys a new StataToken for that underlying asset, registers it, and returns the new address.

function getStataTokens() external view returns (address[] memory)

Returns all StataToken instances deployed via this factory.

function getStataToken(address underlying) external view returns (address)

Returns the StataToken address for a given underlying asset.

function POOL() external view returns (IPool)

Returns the address of the Aave pool associated with this factory.

function PROXY_ADMIN() external view returns (address)

Returns the address of the proxy admin used for the StataToken proxies.

function TRANSPARENT_PROXY_FACTORY() external view returns (ITransparentProxyFactory)

Returns the address of the transparent proxy factory used for creating new StataToken proxies.

function STATA_TOKEN_IMPL() external view returns (address)

Returns the address of the StataToken implementation used when deploying new StataToken instances.

Implements a variable debt token to track the borrowing positions of users at variable rate mode.

transfer and approve functionalities are disabled as variable debt tokens are non-transferable.

The vToken value is pegged 1:1 to the value of underlying borrowed asset and represents the current total amount owed to the protocol i.e. principal debt + interest accrued.

The VariableDebtToken contract inherits the DebtTokenBase and ScaledBalanceTokenBase token contracts.

The source code is available on GitHub.

function initialize(    IPool initializingPool,    address underlyingAsset,    IAaveIncentivesController incentivesController,    uint8 debtTokenDecimals,    string memory debtTokenName,    string memory debtTokenSymbol,    bytes calldata params) external override initializer

Called when variableDebtToken instance is initialised.

function mint(    address user,    address onBehalfOf,    uint256 amount,    uint256 index) external virtual override onlyPool returns (bool, uint256)

Mints the variable debt token to the onBehalfOf address.

function burn(    address from,    uint256 amount,    uint256 index) external virtual override onlyPool returns (uint256)

Burns user variable debt.

In some instances, a burn transaction will emit a mint event if the amount to burn is less than the interest that the user accrued.

function UNDERLYING_ASSET_ADDRESS() external view override returns (address)

Returns the address of the underlying asset of this variableDebtToken (e.g. WETH for variableDebtWETH)

function balanceOf(address account) public view virtual override returns (uint256)

Returns the amount of tokens owned by account - the most up to date accumulated debt (principal + interest) of the user.

Standard ERC20 function.

function totalSupply() public view virtual override returns (uint256)

Returns the amount of tokens in existence - the most up to date total debt accrued by all protocol users for that specific variable rate of debt token.

Standard ERC20 function.

function getRevision() internal pure virtual override returns (uint256)

Returns the revision number of the contract. Needs to be defined in the inherited class as a constant.

Returns 0x1.

Being non-transferrable, the variable debt token does not implement any of the standard ERC20 functions for transfer and allowance.

The following functions below will revert with the error code 80, OPERATION_NOT_SUPPORTED: transfer, allowance, approve, transferFrom, increaseAllowance, decreaseAllowance.