48 lines
1.6 KiB
Solidity
48 lines
1.6 KiB
Solidity
pragma solidity ^0.5.11;
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import "./SafeMath.sol";
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contract ERC20 {
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using SafeMath for uint256;
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mapping (address => uint256) public balanceOf;
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mapping (address => mapping (address => uint256)) public allowance;
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event Transfer(address indexed from, address indexed to, uint256 value);
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event Approval(address indexed owner, address indexed spender, uint256 value);
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uint256 public totalSupply;
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uint256 internal constant MAX_UINT256 = 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF;
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function transfer(address to, uint256 value) public returns (bool) {
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balanceOf[msg.sender] = balanceOf[msg.sender].sub(value);
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balanceOf[to] = balanceOf[to].add(value);
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emit Transfer(msg.sender, to, value);
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return true;
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}
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function transferFrom(address from, address to, uint256 value) public returns (bool) {
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if (allowance[from][msg.sender] < MAX_UINT256) {
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allowance[from][msg.sender] = allowance[from][msg.sender].sub(value);
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}
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balanceOf[from] = balanceOf[from].sub(value);
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balanceOf[to] = balanceOf[to].add(value);
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emit Transfer(from, to, value);
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return true;
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}
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function approve(address spender, uint256 value) public returns (bool) {
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allowance[msg.sender][spender] = value;
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emit Approval(msg.sender, spender, value);
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return true;
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}
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function burn(uint256 value) public {
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totalSupply = totalSupply.sub(value);
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balanceOf[msg.sender] = balanceOf[msg.sender].sub(value);
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emit Transfer(msg.sender, address(0), value);
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}
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// TODO: metaapprove https://github.com/makerdao/dss/blob/master/src/dai.sol
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}
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