mirror of
https://github.com/ethereum/solidity
synced 2023-10-03 13:03:40 +00:00
66 lines
2.3 KiB
Solidity
66 lines
2.3 KiB
Solidity
|
pragma solidity ^0.4.11;
|
||
|
|
|
||
|
|
|
||
|
|
import './BasicToken.sol';
|
||
|
|
import './ERC20.sol';
|
||
|
|
|
||
|
|
|
||
|
|
/**
|
||
|
|
* @title Standard ERC20 token
|
||
|
|
*
|
||
|
|
* @dev Implementation of the basic standard token.
|
||
|
|
* @dev https://github.com/ethereum/EIPs/issues/20
|
||
|
|
* @dev Based on code by FirstBlood: https://github.com/Firstbloodio/token/blob/master/smart_contract/FirstBloodToken.sol
|
||
|
|
*/
|
||
|
|
contract StandardToken is ERC20, BasicToken {
|
||
|
|
|
||
|
|
mapping (address => mapping (address => uint256)) allowed;
|
||
|
|
|
||
|
|
|
||
|
|
/**
|
||
|
|
* @dev Transfer tokens from one address to another
|
||
|
|
* @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 amout of tokens to be transfered
|
||
|
|
*/
|
||
|
|
function transferFrom(address _from, address _to, uint256 _value) {
|
||
|
|
var _allowance = allowed[_from][msg.sender];
|
||
|
|
|
||
|
|
// Check is not needed because sub(_allowance, _value) will already throw if this condition is not met
|
||
|
|
// if (_value > _allowance) throw;
|
||
|
|
|
||
|
|
balances[_to] = balances[_to].add(_value);
|
||
|
|
balances[_from] = balances[_from].sub(_value);
|
||
|
|
allowed[_from][msg.sender] = _allowance.sub(_value);
|
||
|
|
Transfer(_from, _to, _value);
|
||
|
|
}
|
||
|
|
|
||
|
|
/**
|
||
|
|
* @dev Aprove the passed address to spend the specified amount of tokens on behalf of msg.sender.
|
||
|
|
* @param _spender The address which will spend the funds.
|
||
|
|
* @param _value The amount of tokens to be spent.
|
||
|
|
*/
|
||
|
|
function approve(address _spender, uint256 _value) {
|
||
|
|
|
||
|
|
// To change the approve amount you first have to reduce the addresses`
|
||
|
|
// allowance to zero by calling `approve(_spender, 0)` if it is not
|
||
|
|
// already 0 to mitigate the race condition described here:
|
||
|
|
// https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
|
||
|
|
if ((_value != 0) && (allowed[msg.sender][_spender] != 0)) throw;
|
||
|
|
|
||
|
|
allowed[msg.sender][_spender] = _value;
|
||
|
|
Approval(msg.sender, _spender, _value);
|
||
|
|
}
|
||
|
|
|
||
|
|
/**
|
||
|
|
* @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 specifing the amount of tokens still avaible for the spender.
|
||
|
|
*/
|
||
|
|
function allowance(address _owner, address _spender) constant returns (uint256 remaining) {
|
||
|
|
return allowed[_owner][_spender];
|
||
|
|
}
|
||
|
|
|
||
|
|
}
|