Contract Source Code:
File 1 of 1 : EARN
/**
*Submitted for verification at Etherscan.io on 2020-09-18
*/
/**
* TICKER : EARN
* TOKEN NAME : Yearn Classic Token
* TOTAL SUPPLY : 21000
* (c) yearnclassic.finance
*/
pragma solidity ^0.5.2;
// File: openzeppelin-solidity/contracts/token/ERC20/IERC20.sol
/**
* @title ERC20 interface
* @dev see https://eips.ethereum.org/EIPS/eip-20
*/
interface IERC20 {
function transfer(address to, uint256 value) external returns (bool);
function approve(address spender, uint256 value) external returns (bool);
function transferFrom(address from, address to, uint256 value) external returns (bool);
function totalSupply() external view returns (uint256);
function balanceOf(address who) external view returns (uint256);
function allowance(address owner, address spender) external view returns (uint256);
event Transfer(address indexed from, address indexed to, uint256 value);
event Approval(address indexed owner, address indexed spender, uint256 value);
}
// File: openzeppelin-solidity/contracts/math/SafeMath.sol
pragma solidity ^0.5.2;
/**
* @title SafeMath
* @dev Unsigned math operations with safety checks that revert on error
*/
library SafeMath {
/**
* @dev Multiplies two unsigned integers, reverts on overflow.
*/
function mul(uint256 a, uint256 b) internal pure returns (uint256) {
// Gas optimization: this is cheaper than requiring 'a' not being zero, but the
// benefit is lost if 'b' is also tested.
// See: https://github.com/OpenZeppelin/openzeppelin-solidity/pull/522
if (a == 0) {
return 0;
}
uint256 c = a * b;
require(c / a == b);
return c;
}
/**
* @dev Integer division of two unsigned integers truncating the quotient, reverts on division by zero.
*/
function div(uint256 a, uint256 b) internal pure returns (uint256) {
// Solidity only automatically asserts when dividing by 0
require(b > 0);
uint256 c = a / b;
// assert(a == b * c + a % b); // There is no case in which this doesn't hold
return c;
}
/**
* @dev Subtracts two unsigned integers, reverts on overflow (i.e. if subtrahend is greater than minuend).
*/
function sub(uint256 a, uint256 b) internal pure returns (uint256) {
require(b <= a);
uint256 c = a - b;
return c;
}
/**
* @dev Adds two unsigned integers, reverts on overflow.
*/
function add(uint256 a, uint256 b) internal pure returns (uint256) {
uint256 c = a + b;
require(c >= a);
return c;
}
/**
* @dev Divides two unsigned integers and returns the remainder (unsigned integer modulo),
* reverts when dividing by zero.
*/
function mod(uint256 a, uint256 b) internal pure returns (uint256) {
require(b != 0);
return a % b;
}
}
// File: openzeppelin-solidity/contracts/token/ERC20/ERC20.sol
pragma solidity ^0.5.2;
/**
* @title Standard ERC20 token
*
* @dev Implementation of the basic standard token.
* https://eips.ethereum.org/EIPS/eip-20
*
* This implementation emits additional Approval events, allowing applications to reconstruct the allowance status for
* all accounts just by listening to said events. Note that this isn't required by the specification, and other
* compliant implementations may not do it.
*/
contract ERC20 is IERC20 {
using SafeMath for uint256;
mapping (address => uint256) private _balances;
mapping (address => mapping (address => uint256)) private _allowed;
uint256 private _totalSupply;
/**
* @dev Total number of tokens in existence
*/
function totalSupply() public view returns (uint256) {
return _totalSupply;
}
/**
* @dev Gets the balance of the specified address.
* @param owner The address to query the balance of.
* @return A uint256 representing the amount owned by the passed address.
*/
function balanceOf(address owner) public view returns (uint256) {
return _balances[owner];
}
/**
* @dev Function to check the amount of tokens that an owner allowed to a spender.
* @param owner address The address which owns the funds.
* @param spender address The address which will spend the funds.
* @return A uint256 specifying the amount of tokens still available for the spender.
*/
function allowance(address owner, address spender) public view returns (uint256) {
return _allowed[owner][spender];
}
/**
* @dev Transfer token to a specified address
* @param to The address to transfer to.
* @param value The amount to be transferred.
*/
function transfer(address to, uint256 value) public returns (bool) {
_transfer(msg.sender, to, value);
return true;
}
/**
* @dev Approve the passed address to spend the specified amount of tokens on behalf of msg.sender.
* Beware that changing an allowance with this method brings the risk that someone may use both the old
* and the new allowance by unfortunate transaction ordering. One possible solution to mitigate this
* race condition is to first reduce the spender's allowance to 0 and set the desired value afterwards:
* https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
* @param spender The address which will spend the funds.
* @param value The amount of tokens to be spent.
*/
function approve(address spender, uint256 value) public returns (bool) {
_approve(msg.sender, spender, value);
return true;
}
/**
* @dev Transfer tokens from one address to another.
* Note that while this function emits an Approval event, this is not required as per the specification,
* and other compliant implementations may not emit the event.
* @param from address The address which you want to send tokens from
* @param to address The address which you want to transfer to
* @param value uint256 the amount of tokens to be transferred
*/
function transferFrom(address from, address to, uint256 value) public returns (bool) {
_transfer(from, to, value);
_approve(from, msg.sender, _allowed[from][msg.sender].sub(value));
return true;
}
/**
* @dev Increase the amount of tokens that an owner allowed to a spender.
* approve should be called when _allowed[msg.sender][spender] == 0. To increment
* allowed value is better to use this function to avoid 2 calls (and wait until
* the first transaction is mined)
* From MonolithDAO Token.sol
* Emits an Approval event.
* @param spender The address which will spend the funds.
* @param addedValue The amount of tokens to increase the allowance by.
*/
function increaseAllowance(address spender, uint256 addedValue) public returns (bool) {
_approve(msg.sender, spender, _allowed[msg.sender][spender].add(addedValue));
return true;
}
/**
* @dev Decrease the amount of tokens that an owner allowed to a spender.
* approve should be called when _allowed[msg.sender][spender] == 0. To decrement
* allowed value is better to use this function to avoid 2 calls (and wait until
* the first transaction is mined)
* From MonolithDAO Token.sol
* Emits an Approval event.
* @param spender The address which will spend the funds.
* @param subtractedValue The amount of tokens to decrease the allowance by.
*/
function decreaseAllowance(address spender, uint256 subtractedValue) public returns (bool) {
_approve(msg.sender, spender, _allowed[msg.sender][spender].sub(subtractedValue));
return true;
}
/**
* @dev Transfer token for a specified addresses
* @param from The address to transfer from.
* @param to The address to transfer to.
* @param value The amount to be transferred.
*/
function _transfer(address from, address to, uint256 value) internal {
require(to != address(0));
_balances[from] = _balances[from].sub(value);
_balances[to] = _balances[to].add(value);
emit Transfer(from, to, value);
}
/**
* @dev Internal function that mints an amount of the token and assigns it to
* an account. This encapsulates the modification of balances such that the
* proper events are emitted.
* @param account The account that will receive the created tokens.
* @param value The amount that will be created.
*/
function _mint(address account, uint256 value) internal {
require(account != address(0));
_totalSupply = _totalSupply.add(value);
_balances[account] = _balances[account].add(value);
emit Transfer(address(0), account, value);
}
/**
* @dev Internal function that burns an amount of the token of a given
* account.
* @param account The account whose tokens will be burnt.
* @param value The amount that will be burnt.
*/
function _burn(address account, uint256 value) internal {
require(account != address(0));
_totalSupply = _totalSupply.sub(value);
_balances[account] = _balances[account].sub(value);
emit Transfer(account, address(0), value);
}
/**
* @dev Approve an address to spend another addresses' tokens.
* @param owner The address that owns the tokens.
* @param spender The address that will spend the tokens.
* @param value The number of tokens that can be spent.
*/
function _approve(address owner, address spender, uint256 value) internal {
require(spender != address(0));
require(owner != address(0));
_allowed[owner][spender] = value;
emit Approval(owner, spender, value);
}
/**
* @dev Internal function that burns an amount of the token of a given
* account, deducting from the sender's allowance for said account. Uses the
* internal burn function.
* Emits an Approval event (reflecting the reduced allowance).
* @param account The account whose tokens will be burnt.
* @param value The amount that will be burnt.
*/
function _burnFrom(address account, uint256 value) internal {
_burn(account, value);
_approve(account, msg.sender, _allowed[account][msg.sender].sub(value));
}
}
// File: openzeppelin-solidity/contracts/token/ERC20/ERC20Detailed.sol
pragma solidity ^0.5.2;
/**
* @title ERC20Detailed token
* @dev The decimals are only for visualization purposes.
* All the operations are done using the smallest and indivisible token unit,
* just as on Ethereum all the operations are done in wei.
*/
contract ERC20Detailed is IERC20 {
string private _name;
string private _symbol;
uint8 private _decimals;
constructor (string memory name, string memory symbol, uint8 decimals) public {
_name = name;
_symbol = symbol;
_decimals = decimals;
}
/**
* @return the name of the token.
*/
function name() public view returns (string memory) {
return _name;
}
/**
* @return the symbol of the token.
*/
function symbol() public view returns (string memory) {
return _symbol;
}
/**
* @return the number of decimals of the token.
*/
function decimals() public view returns (uint8) {
return _decimals;
}
}
// File: openzeppelin-solidity/contracts/token/ERC20/ERC20Burnable.sol
pragma solidity ^0.5.2;
/**
* @title Burnable Token
* @dev Token that can be irreversibly burned (destroyed).
*/
contract ERC20Burnable is ERC20 {
/**
* @dev Burns a specific amount of tokens.
* @param value The amount of token to be burned.
*/
function burn(uint256 value) public {
_burn(msg.sender, value);
}
/**
* @dev Burns a specific amount of tokens from the target address and decrements allowance
* @param from address The account whose tokens will be burned.
* @param value uint256 The amount of token to be burned.
*/
function burnFrom(address from, uint256 value) public {
_burnFrom(from, value);
}
}
// File: EARN.sol
pragma solidity ^0.5.0;
contract EARN is ERC20, ERC20Detailed, ERC20Burnable {
constructor() ERC20Detailed('Yearn Classic', 'EARN', 18) public {
_mint(msg.sender, 21000 * 10 ** 18);
}
}