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openzeppelin-contracts/contracts/StandardToken.sol

56 lines
1.6 KiB

pragma solidity ^0.4.0;
import './ERC20.sol';
import './SafeMath.sol';
/**
* ERC20 token
*
* https://github.com/ethereum/EIPs/issues/20
* Based on code by FirstBlood:
* https://github.com/Firstbloodio/token/blob/master/smart_contract/FirstBloodToken.sol
*/
contract StandardToken is ERC20, SafeMath {
mapping(address => uint) balances;
mapping (address => mapping (address => uint)) allowed;
function transfer(address _to, uint _value) returns (bool success) {
if (balances[msg.sender] < _value) {
throw;
}
balances[msg.sender] = safeSub(balances[msg.sender], _value);
balances[_to] = safeAdd(balances[_to], _value);
Transfer(msg.sender, _to, _value);
return true;
}
function transferFrom(address _from, address _to, uint _value) returns (bool success) {
var _allowance = allowed[_from][msg.sender];
if (balances[_from] < _value ||
_allowance < _value) {
throw;
}
balances[_to] = safeAdd(balances[_to], _value);
balances[_from] = safeSub(balances[_from], _value);
allowed[_from][msg.sender] = safeSub(_allowance, _value);
Transfer(_from, _to, _value);
return true;
}
function balanceOf(address _owner) constant returns (uint balance) {
return balances[_owner];
}
function approve(address _spender, uint _value) returns (bool success) {
allowed[msg.sender][_spender] = _value;
Approval(msg.sender, _spender, _value);
return true;
}
function allowance(address _owner, address _spender) constant returns (uint remaining) {
return allowed[_owner][_spender];
}
}