ERC20Upgradeable

Inherits: Initializable, IERC20Permit, IERC20, IERC20Metadata

Author: StakeWise

Modern and gas efficient ERC20 + EIP-2612 implementation

State Variables

_permitTypeHash

bytes32 private constant _permitTypeHash =
    keccak256("Permit(address owner,address spender,uint256 value,uint256 nonce,uint256 deadline)");

name

Returns the name of the token.

string public override name;

symbol

Returns the symbol of the token.

string public override symbol;

decimals

Returns the decimals places of the token.

uint8 public constant override decimals = 18;

allowance

Returns the remaining number of tokens that spender is allowed to spend on behalf of owner

mapping(address => mapping(address => uint256)) public override allowance;

nonces

Returns the current nonce for owner. This value must be included whenever a signature is generated for {permit}. Every successful call to {permit} increases owner's nonce by one. This prevents a signature from being used multiple times.

mapping(address => uint256) public override nonces;

_initialChainId

Note: oz-upgrades-unsafe-allow: state-variable-immutable

uint256 private immutable _initialChainId;

_initialDomainSeparator

bytes32 private _initialDomainSeparator;

__gap

This empty reserved space is put in place to allow future versions to add new variables without shifting down storage in the inheritance chain. See https://docs.openzeppelin.com/contracts/4.x/upgradeable#storage_gaps

uint256[50] private __gap;

Functions

constructor

Constructor

Since the immutable variable value is stored in the bytecode, its value would be shared among all proxies pointing to a given contract instead of each proxy’s storage.

Note: oz-upgrades-unsafe-allow: constructor

constructor();

approve

Sets amount as the allowance of spender over the caller's tokens.

Be aware of front-running risks: https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729

function approve(address spender, uint256 amount) public override returns (bool);

transfer

Moves amount tokens from the caller's account to to.

function transfer(address to, uint256 amount) public virtual override returns (bool);

transferFrom

Moves amount tokens from from to to using the allowance mechanism. amount is then deducted from the caller's allowance.

function transferFrom(address from, address to, uint256 amount) public virtual override returns (bool);

permit

*Sets value as the allowance of spender over owner's tokens, given owner's signed approval. IMPORTANT: The same issues {IERC20-approve} has related to transaction ordering also apply here. Emits an {Approval} event. Requirements:

spender cannot be the zero address.
deadline must be a timestamp in the future.
v, r and s must be a valid secp256k1 signature from owner over the EIP712-formatted function arguments.
the signature must use owner's current nonce (see {nonces}). For more information on the signature format, see the https://eips.ethereum.org/EIPS/eip-2612#specification[relevant EIP section]. CAUTION: See Security Considerations above.*

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

DOMAIN_SEPARATOR

Returns the domain separator used in the encoding of the signature for {permit}, as defined by {EIP712}.

function DOMAIN_SEPARATOR() public view override returns (bytes32);

_computeDomainSeparator

Computes the hash of the EIP712 typed data

This function is used to compute the hash of the EIP712 typed data

function _computeDomainSeparator() private view returns (bytes32);

_transfer

Moves amount of tokens from from to to. Emits a {Transfer} event.

function _transfer(address from, address to, uint256 amount) internal virtual;