ERC20Permit extension to pay gas fees by only BLB token.
AccessControl interface for the administration of the tokens.
Using TransferControl interface:
The admin can set a monthly fraction of the spending limit which means that every user can only spend the specified fraction of their tokens every month.
admin can restrict some addresses and specify a different limitation which makes them able to spend their tokens independent of the prevailing limitations.
Using TransactionFee interface:
Admins can set a fraction or a constant amount for every BLB token transfer. so it is considered as the internal gas fee.
transaction fees are sent to a third address which can be set by the admin.
if the transaction fee receiver is zero address, then the fee tokens are burned.
External Functions API:
BLB token contract consists of two main parts:
the openzeppelin pre-built open-source contracts.
the custom-developed unique contracts of BLB token.
we explain custom-developed functions here in detail. and link others to the openzeppelin docs.
/**
* Creates amount tokens and assigns them to account, increasing the total supply.
*
* Emits a transfer event from set to the zero address.
*
* Requirements:
*
* account cannot be the zero address.
* only role MINTER_ROLE can call this function.
*/
function mint(address to, uint256 amount)
function
/**
* Mint amount of token to every member in accounts.
*
* Emits some transfer events with from set to the zero address to every account.
*
* Requirements:
*
* accounts cannot be the zero address.
* only role MINTER_ROLE can call this function.
*/
function mintBatch(address[] accounts, uint256 amount)
abstract contract (TransactionFee)
deduct the transaction fee of every token transfer and send it to a third address.
functions and events API:
/**
* @return feeAmount numerator of transaction fee which denominator is 1,000,000.
* @return feeFraction independent transaction fee for every token transfer.
* @return feeReceiver address of the fee receiver.
*/
function feeDetails()
external function
/**
* @return fee transaction fee corresponding to the transferring amount.
* @notice if there is a fee amount, the transaction fee is not proportional to the
* transferring amount.
*/
function transactionFee(uint256 transferingAmount)
external function
/**
* @notice set amount or fraction and receiver of BLB transaction fees.
*
* @notice if transaction receiver is zero address, the transaction fee will be burned.
*
* @notice requirement:
* - Only role FEE_SETTER can call this function.
* - one of the feeAmount or feeFraction must be zero.
* - fee fraction can be a maximum of 50,000 which equals 5% of the transactions
*
* @dev emits a SetTransactionFee event
*/
function setTransactionFee(uint256 _feeAmount, uint256 _feeFraction, address _feeReceiver)
event
/**
* @dev emits when the admin sets a new transaction fee plan.
*/
event SetTransactionFee(uint256 _feeAmount, uint256 _feeFraction, address _feeReceiver)
abstract contract (TransferControl)
control BLB transfers.
users may have access to transfer their whole BLB balance or only a certain fraction every month(it depends on the monthly limit).
some specific addresses may have restricted access to transfer.
contract admin can restrict every desired address and also determine a spending limit for all users.
if an address is restricted then the public monthly limit is diactivated for it.
functions and events API:
external function
/**
* @notice set spend limit for monthly transfers.
* @notice there is no transfer limit if the fraction is 10**6.
*
* @param fraction the numerator of transfer limit rate which denominator
* is 10**6.
*
* @notice require:
* - only role TRANSFER_LIMIT_SETTER can call this function.
* - maximum fraction can be 10**6 (equal to 100%).
*
* @notice emits a SetMonthlyTransferFraction event.
*/
function setMonthlyTransferLimit(uint256 fraction)
external function
/**
* @notice restrict an address
* @notice the address `addr` will be only able to spend as much as `amount`.
*
* @param addr the restricted address.
* @param amount restricted spendable amount.
*
* @notice require:
* - only the RESTRICTOR_ROLE address can call this function.
*
* @notice emits a Restrict event.
*/
function restrict(address addr, uint256 amount)
external function
/**
* @notice district an address
* @notice the address `addr` will be free to spend their BLB like regular
* addresses.
*
* @param addr the address that is going to be districted.
*
* @notice require:
* - only RESTRICTOR_ROLE address can call this function.
*
* @notice emits a District event.
*/
function district(address addr)
/**
* @return fraction the numerator of monthly transfer limit rate which denominator
* is 10**6.
*/
function monthlyLimit()
external function
/**
* @return boolean true if the address is restricted.
*
* @param addr the address that is going to be checked.
*/
function isRestricted(address addr)
external function
/**
* @return amount that the address can spend.
*
* @dev if the address is restricted, the amount equals the remaining spendable amount for the
* address. else if there is a spending limit active for the contract, the amount equals the
* address's remaining monthly spendable amount. else the amount equals the balance of the address.
*
* @param addr the address that is being checked.
*/
function canSpend(address addr)
event
/**
* @dev emits when the admin sets a new value as the monthlyLimit.
*/
event SetMonthlyTransferLimit(uint256 fraction)
event
/**
* @dev emits when the admin restricts an address.
*/
event Restrict(address addr, uint256 amount);
event
/**
* @dev emits when the admin districts an address.
*/
event District(address addr);
