SPAToken

Git Source

Inherits: Initializable, OwnableUpgradeable, ISPAToken

Author: Nuts Finance Developer

ERC20 token minted by the StableSwap pools.

SPA token is ERC20 rebase token minted by StableSwap pools for liquidity providers. SPA token balances are dynamic and represent the holder's share in the total amount of SPA tokens controlled by the protocol. Account shares aren't normalized, so the contract also stores the sum of all shares to calculate each account's token balance which equals to: shares[account] * _totalSupply / _totalShares where the _totalSupply is the total supply of spaToken controlled by the protocol.

State Variables

INFINITE_ALLOWANCE

Constant value representing an infinite allowance.

uint256 internal constant INFINITE_ALLOWANCE = ~uint256(0);

BUFFER_DENOMINATOR

Constant value representing the denominator for the buffer rate.

uint256 public constant BUFFER_DENOMINATOR = 10 ** 10;

NUMBER_OF_DEAD_SHARES

Constant value representing the number of dead shares.

uint256 public constant NUMBER_OF_DEAD_SHARES = 1000;

totalShares

The total amount of shares.

uint256 public totalShares;

totalSupply

The total supply of spaToken

uint256 public totalSupply;

totalRewards

The total amount of rewards

uint256 public totalRewards;

shares

The mapping of account shares.

mapping(address => uint256) public shares;

allowances

The mapping of account allowances.

mapping(address => mapping(address => uint256)) private allowances;

bufferPercent

The buffer rate.

uint256 public bufferPercent;

bufferAmount

The buffer amount.

uint256 public bufferAmount;

tokenName

The token name.

string internal tokenName;

tokenSymbol

The token symbol.

string internal tokenSymbol;

bufferBadDebt

The bad debt of the buffer.

uint256 public bufferBadDebt;

pool

The address of SPA pool.

address public pool;

Functions

constructor

constructor();

initialize

function initialize(
    string memory _name,
    string memory _symbol,
    uint256 _buffer,
    address _keeper,
    address _pool
)
    public
    initializer;

transferShares

Moves _sharesAmount token shares from the caller's account to the _recipient account.

The _sharesAmount argument is the amount of shares, not tokens.

function transferShares(address _recipient, uint256 _sharesAmount) external returns (uint256);

Returns

transferSharesFrom

Moves _sharesAmount token shares from the _sender account to the _recipient account.

The _sharesAmount argument is the amount of shares, not tokens.

function transferSharesFrom(address _sender, address _recipient, uint256 _sharesAmount) external returns (uint256);

Returns

mintShares

Mints shares for the _account and transfers them to the _account.

function mintShares(address _account, uint256 _tokenAmount) external;

burnShares

Burns shares from the _account.

function burnShares(uint256 _tokenAmount) external;

burnSharesFrom

Burns shares from the _account.

function burnSharesFrom(address _account, uint256 _tokenAmount) external;

transfer

Moves _amount tokens from the caller's account to the _recipientaccount.

The _amount argument is the amount of tokens, not shares.

function transfer(address _recipient, uint256 _amount) external returns (bool);

Returns

approve

Sets _amount as the allowance of _spender over the caller's tokens.

The _amount argument is the amount of tokens, not shares.

function approve(address _spender, uint256 _amount) external returns (bool);

Returns

transferFrom

Moves _amount tokens from _sender to _recipient using the allowance mechanism. _amount is then deducted from the caller's allowance.

The _amount argument is the amount of tokens, not shares.

function transferFrom(address _sender, address _recipient, uint256 _amount) external returns (bool);

Returns

increaseAllowance

Atomically increases the allowance granted to _spender by the caller by _addedValue. This is an alternative to approve that can be used as a mitigation for problems described in: https://github.com/OpenZeppelin/openzeppelin-contracts/blob/b709eae01d1da91902d06ace340df6b324e6f049/contracts/token/ERC20/IERC20.sol#L57 Emits an Approval event indicating the updated allowance.

function increaseAllowance(address _spender, uint256 _addedValue) external returns (bool);

decreaseAllowance

Atomically decreases the allowance granted to _spender by the caller by _subtractedValue. This is an alternative to approve that can be used as a mitigation for problems described in: https://github.com/OpenZeppelin/openzeppelin-contracts/blob/b709eae01d1da91902d06ace340df6b324e6f049/contracts/token/ERC20/IERC20.sol#L57 Emits an Approval event indicating the updated allowance.

function decreaseAllowance(address _spender, uint256 _subtractedValue) external returns (bool);

setBuffer

This function is called by the keeper to set the buffer rate.

function setBuffer(uint256 _buffer) external onlyOwner;

setSymbol

This function is called by the keeper to set the token symbol.

function setSymbol(string memory _symbol) external onlyOwner;

addTotalSupply

This function is called only by a stableSwap pool to increase the total supply of SPAToken by the staking rewards and the swap fee.

function addTotalSupply(uint256 _amount) external;

removeTotalSupply

This function is called only by a stableSwap pool to decrease the total supply of SPAToken by lost amount.

function removeTotalSupply(uint256 _amount, bool isBuffer, bool withDebt) external;

Parameters

addBuffer

This function is called only by a stableSwap pool to increase the buffer amount of SPAToken

function addBuffer(uint256 _amount, bool withDebt) external;

withdrawBuffer

Withdraw _amount from Buffer and mint SPAToken shares to _to Callable only by Governor via Keeper (which is owner)

function withdrawBuffer(address _to, uint256 _amount) external onlyOwner;

Parameters

name

Returns the name of the token.

function name() external view returns (string memory);

Returns

symbol

Returns the symbol of the token.

function symbol() external view returns (string memory);

Returns

balanceOf

Balances are dynamic and equal the _account's share in the amount of the total spaToken controlled by the protocol. See sharesOf.

function balanceOf(address _account) external view returns (uint256);

Returns

allowance

This value changes when approve or transferFrom is called.

function allowance(address _owner, address _spender) external view returns (uint256);

Returns

sharesOf

function sharesOf(address _account) external view returns (uint256);

Returns

decimals

Returns the decimals of the token.

function decimals() external pure returns (uint8);

Returns

getPeggedTokenByShares

function getPeggedTokenByShares(uint256 _sharesAmount) public view returns (uint256);

Returns

getSharesByPeggedToken

function getSharesByPeggedToken(uint256 _spaTokenAmount) public view returns (uint256);

Returns

_transfer

Moves _amount tokens from _sender to _recipient. Emits a Transfer event. Emits a TransferShares event.

function _transfer(address _sender, address _recipient, uint256 _amount) internal;

_approve

Sets _amount as the allowance of _spender over the _owner s tokens. Emits an Approval event.

function _approve(address _owner, address _spender, uint256 _amount) internal;

_spendAllowance

Updates owner s allowance for spender based on spent amount. Does not update the allowance amount in case of infinite allowance. Revert if not enough allowance is available. Might emit an {Approval} event.

function _spendAllowance(address _owner, address _spender, uint256 _amount) internal;

_transferShares

Moves _sharesAmount shares from _sender to _recipient.

function _transferShares(address _sender, address _recipient, uint256 _sharesAmount) internal;

_mintShares

Creates _sharesAmount shares and assigns them to _recipient, increasing the total amount of shares.

function _mintShares(address _recipient, uint256 _tokenAmount) internal returns (uint256 newTotalShares);

_burnShares

Destroys _sharesAmount shares from _account's holdings, decreasing the total amount of shares.

function _burnShares(address _account, uint256 _tokenAmount) internal returns (uint256 newTotalShares);

_emitTransferEvents

Emits Transfer and TransferShares events.

function _emitTransferEvents(address _from, address _to, uint256 _tokenAmount, uint256 _sharesAmount) internal;

_emitTransferAfterMintingShares

Emits Transfer and TransferShares events after minting shares.

function _emitTransferAfterMintingShares(address _to, uint256 _sharesAmount) internal;

_emitTransferAfterBurningShares

Emits Transfer and TransferShares events after burning shares.

function _emitTransferAfterBurningShares(address _from, uint256 _sharesAmount) internal;

_sharesOf

function _sharesOf(address _account) internal view returns (uint256);

Returns

Events

TransferShares

Emitted when shares are transferred.

event TransferShares(address indexed from, address indexed to, uint256 sharesValue);

RewardsMinted

Emitted when rewards are minted.

event RewardsMinted(uint256 amount, uint256 actualAmount);

SetBufferPercent

Emitted when the buffer rate is set.

event SetBufferPercent(uint256);

BufferIncreased

Emitted when the buffer is increased.

event BufferIncreased(uint256, uint256);

BufferDecreased

Emitted when the buffer is decreased.

event BufferDecreased(uint256, uint256);

BufferWithdrawn

Emitted when Buffer is withdrawn to Treasury

event BufferWithdrawn(address indexed to, uint256 amount, uint256 bufferLeft);

NegativelyRebased

Emitted when there is negative rebase.

event NegativelyRebased(uint256, uint256);

SymbolModified

Emitted when the symbol is modified.

event SymbolModified(string);

Errors

AllowanceBelowZero

Error thrown when the allowance is below zero.

error AllowanceBelowZero();

OutOfRange

Error thrown when array index is out of range.

error OutOfRange();

NoPool

Error thrown when the pool is not the caller.

error NoPool();

InvalidAmount

Error thrown when the amount is invalid.

error InvalidAmount();

InsufficientBuffer

Error thrown when the buffer is insufficient.

error InsufficientBuffer();

ApproveFromZeroAddr

Error thrown when the sender's address is zero.

error ApproveFromZeroAddr();

ApproveToZeroAddr

Error thrown when the recipient's address is zero.

error ApproveToZeroAddr();

ZeroAddress

Error thrown when the address is zero.

error ZeroAddress();

TransferToSPATokenContract

Error thrown when transferring to the spaToken contract.

error TransferToSPATokenContract();

MintToZeroAddr

Error thrown when minting to the zero address.

error MintToZeroAddr();

BurnFromZeroAddr

Error thrown when burning from the zero address.

error BurnFromZeroAddr();

InsufficientSupply

Error thrown when the supply is insufficient.

error InsufficientSupply();