ERC contract checker guide¶

Please make sure that lityc has been installed on your system. If not, please follow Getting started.

ERC20 Contract Standard Checker¶

Enable contract standard checker with specific ERC¶

$ lityc --contract-standard ERC20 <contract file>

Examples¶

ERC20 Interface (erc20_interface.sol)

pragma lity ^1.2.4;

contract ERC20Interface {
  function totalSupply() public view returns (uint);
  function balanceOf(address tokenOwner) public view returns (uint balance);
  function allowance(address tokenOwner, address spender) public view returns (uint remaining);
  function transfer(address to, uint tokens) public returns (bool success);
  function approve(address spender, uint tokens) public returns (bool success);
  function transferFrom(address from, address to, uint tokens) public returns (bool success);

  event Transfer(address indexed from, address indexed to, uint tokens);
  event Approval(address indexed tokenOwner, address indexed spender, uint tokens);
}

Expect output

$ lityc --contract-standard ERC20 erc20_interface.sol

erc20_standard.sol:3:1: Info: ERC20Interface is compatible to ERC20.
contract ERC20Interface {
^ (Relevant source part starts here and spans across multiple lines).

ERC20 Interface with wrong mutability (wrong_mutability.sol)

pragma lity ^1.2.4;

contract ERC20Interface {
  function totalSupply() public pure returns (uint); // mutability should be view, not pure
  function balanceOf(address tokenOwner) public view returns (uint balance);
  function allowance(address tokenOwner, address spender) public view returns (uint remaining);
  function transfer(address to, uint tokens) public returns (bool success);
  function approve(address spender, uint tokens) public returns (bool success);
  function transferFrom(address from, address to, uint tokens) public returns (bool success);

  event Transfer(address indexed from, address indexed to, uint tokens);
  event Approval(address indexed tokenOwner, address indexed spender, uint tokens);
}

Expect output

$ lityc --contract-standard ERC20 wrong_mutability.sol

wrong_mutability.sol:3:1: Info: Missing 'totalSupply' with type signature 'function () view external returns (uint256)'. ERC20Interface is not compatible to ERC20.
contract ERC20Interface {
^ (Relevant source part starts here and spans across multiple lines).

ERC223 Contract Standard Checker¶

Enable contract standard checker with specific ERC¶

$ lityc --contract-standard ERC223 <contract file>

Examples¶

ERC223 Interface (erc223_interface.sol)

pragma lity ^1.2.4;

contract ERC223Interface {
  function totalSupply() public view returns (uint);
  function balanceOf(address tokenOwner) public view returns (uint balance);
  function transfer(address to, uint tokens) public returns (bool success);
  function transfer(address to, uint tokens, bytes data) public returns (bool success);
  event Transfer(address indexed from, address indexed to, uint tokens, bytes data);
}

Expect output

$ lityc --contract-standard ERC223 erc223_interface.sol

erc223_standard.sol:3:1: Info: ERC223Interface is compatible to ERC223.
contract ERC223Interface {
^ (Relevant source part starts here and spans across multiple lines).

ERC223 Token example (erc223_token.sol)

pragma lity ^1.2.4;

library SafeMath {
  function mul(uint a, uint b) internal pure returns (uint) {
  uint c = a * b;
  _assert(a == 0 || c / a == b);
  return c;
}

function div(uint a, uint b) internal pure returns (uint) {
  // _assert(b > 0); // Solidity automatically throws when dividing by 0
  uint c = a / b;
  // _assert(a == b * c + a % b); // There is no case in which this doesn't hold
  return c;
}

function sub(uint a, uint b) internal pure returns (uint) {
  _assert(b <= a);
  return a - b;
}

function add(uint a, uint b) internal pure returns (uint) {
  uint c = a + b;
  _assert(c >= a);
  return c;
}

function max64(uint64 a, uint64 b) internal pure returns (uint64) {
  return a >= b ? a : b;
}

function min64(uint64 a, uint64 b) internal pure returns (uint64) {
  return a < b ? a : b;
}

function max256(uint256 a, uint256 b) internal pure returns (uint256) {
  return a >= b ? a : b;
}

function min256(uint256 a, uint256 b) internal pure returns (uint256) {
  return a < b ? a : b;
}

function _assert(bool assertion) internal pure {
  if (!assertion) {
    revert();
  }
}
}

contract ERC223Interface {
  function totalSupply() public view returns (uint);
  function balanceOf(address tokenOwner) public view returns (uint balance);
  function transfer(address to, uint tokens, bytes data) public returns (bool success);
  function transfer(address to, uint tokens) public returns (bool success);
  event Transfer(address indexed from, address indexed to, uint tokens, bytes data);
}

contract ERC223ReceivingContract {
  function tokenFallback(address _from, uint _value, bytes _data) public;
}

contract ERC223Token is ERC223Interface {
  using SafeMath for uint;

  mapping(address => uint) balances; // List of user balances.

  function totalSupply() public view returns (uint) {
    return 2**18;
  }

  function transfer(address _to, uint _value, bytes _data) public returns (bool) {
    // Standard function transfer similar to ERC20 transfer with no _data .
    // Added due to backwards compatibility reasons .
    uint codeLength;

    assembly {
      // Retrieve the size of the code on target address, this needs assembly .
      codeLength := extcodesize(_to)
    }

    balances[msg.sender] = balances[msg.sender].sub(_value);
    balances[_to] = balances[_to].add(_value);
    if(codeLength>0) {
      ERC223ReceivingContract receiver = ERC223ReceivingContract(_to);
      receiver.tokenFallback(msg.sender, _value, _data);
      return true;
    }
    emit Transfer(msg.sender, _to, _value, _data);
    return true;
  }

  function transfer(address _to, uint _value) public returns (bool) {
    uint codeLength;
    bytes memory empty;

    assembly {
      // Retrieve the size of the code on target address, this needs assembly .
      codeLength := extcodesize(_to)
    }

    balances[msg.sender] = balances[msg.sender].sub(_value);
    balances[_to] = balances[_to].add(_value);
    if(codeLength>0) {
      ERC223ReceivingContract receiver = ERC223ReceivingContract(_to);
      receiver.tokenFallback(msg.sender, _value, empty);
      return true;
    }
    emit Transfer(msg.sender, _to, _value, empty);
    return true;
  }

  function balanceOf(address _owner) public view returns (uint balance) {
    return balances[_owner];
  }
}

Expect output

$ lityc --contract-standard ERC223 erc223_token.sol

erc223_token.sol:6:1: Info: Missing 'totalSupply' with type signature 'function () view external returns (uint256)'. SafeMath is not compatible to ERC223.
library SafeMath {
^ (Relevant source part starts here and spans across multiple lines).
erc223_token.sol:54:1: Info: ERC223Interface is compatible to ERC223.
contract ERC223Interface {
^ (Relevant source part starts here and spans across multiple lines).
erc223_token.sol:65:1: Info: Missing 'totalSupply' with type signature 'function () view external returns (uint256)'. ERC223ReceivingContract is not compatible to ERC223.
contract ERC223ReceivingContract {
^ (Relevant source part starts here and spans across multiple lines).
erc223_token.sol:78:1: Info: ERC223Token is compatible to ERC223.
contract ERC223Token is ERC223Interface {
^ (Relevant source part starts here and spans across multiple lines).

ERC721 Contract Standard Checker¶

Enable contract standard checker with specific ERC¶

$ lityc --contract-standard ERC721 <contract file>

Examples¶

ERC721 Interface (erc721_interface.sol)

pragma lity ^1.2.4;

contract ERC721Interface {
  event Transfer(address indexed _from, address indexed _to, uint256 _tokenId);
  event Approval(address indexed _owner, address indexed _approved, uint256 _tokenId);
  event ApprovalForAll(address indexed _owner, address indexed _operator, bool _approved);
  function balanceOf(address _owner) external view returns (uint256);
  function ownerOf(uint256 _tokenId) external view returns (address);
  function safeTransferFrom(address _from, address _to, uint256 _tokenId, bytes data) external payable;
  function safeTransferFrom(address _from, address _to, uint256 _tokenId) external payable;
  function transferFrom(address _from, address _to, uint256 _tokenId) external payable;
  function approve(address _approved, uint256 _tokenId) external payable;
  function setApprovalForAll(address _operator, bool _approved) external;
  function getApproved(uint256 _tokenId) external view returns (address);
  function isApprovedForAll(address _owner, address _operator) external view returns (bool);
  function supportsInterface(bytes4 interfaceID) external view returns (bool);
}

Expect output

$ lityc --contract-standard ERC721 erc721_interface.sol
erc721_interface.sol:3:1: Info: ERC721Interface is compatible to ERC721.
contract ERC721Interface {
^ (Relevant source part starts here and spans across multiple lines).

ERC721 Interface with wrong modification level (wrong_modification_level.sol)

pragma lity ^1.2.4;

contract ERC721Interface {
  event Transfer(address indexed _from, address indexed _to, uint256 _tokenId);
  event Approval(address indexed _owner, address indexed _approved, uint256 _tokenId);
  event ApprovalForAll(address indexed _owner, address indexed _operator, bool _approved);
  function balanceOf(address _owner) external view returns (uint256);
  function ownerOf(uint256 _tokenId) external view returns (address);
  function safeTransferFrom(address _from, address _to, uint256 _tokenId, bytes data) external payable;
  function safeTransferFrom(address _from, address _to, uint256 _tokenId) external payable;
  function transferFrom(address _from, address _to, uint256 _tokenId) external; // missing payable
  function approve(address _approved, uint256 _tokenId) external payable;
  function setApprovalForAll(address _operator, bool _approved) external;
  function getApproved(uint256 _tokenId) external view returns (address);
  function isApprovedForAll(address _owner, address _operator) external view returns (bool);
  function supportsInterface(bytes4 interfaceID) external view returns (bool);
}

Expect output

$ lityc --contract-standard ERC721 wrong_modification_level.sol

wrong_modification_level.sol:3:1: Info: Missing 'transferFrom' with type signature 'function (address,address,uint256) payable external'. ERC721Interface is not compatible to ERC721.
contract ERC721Interface {
^ (Relevant source part starts here and spans across multiple lines).

ERC827 Contract Standard Checker¶

Enable contract standard checker with specific ERC¶

$ lityc --contract-standard ERC827 <contract file>

Examples¶

ERC827 Interface (erc827_standard_no_inheritance.sol)

pragma lity ^1.2.4;

contract ERC827Interface {
  function totalSupply() public view returns (uint256);
  function balanceOf(address who) public view returns (uint256);
  function transfer(address to, uint256 value) public returns (bool);
  function allowance(address owner, address spender) public view returns (uint256);
  function transferFrom(address from, address to, uint256 value) public returns (bool);
  function approve(address spender, uint256 value) public returns (bool);
  event Approval(address indexed owner, address indexed spender, uint256 value);
  event Transfer(address indexed from, address indexed to, uint256 value);
  function transferAndCall(address _to, uint256 _value, bytes _data) public payable returns (bool);
  function transferFromAndCall( address _from, address _to, uint256 _value, bytes _data) public payable returns (bool);
  function approveAndCall(address _spender, uint256 _value, bytes _data) public payable returns (bool);
}

Expect output

$ lityc --contract-standard ERC827 erc827_standard_no_inheritance.sol

erc827_standard_no_inheritance.sol:3:1: Info: ERC827Interface is compatible to ERC827.
contract ERC827Interface {
^ (Relevant source part starts here and spans across multiple lines).

ERC827 Interface inheritance (erc827_inheritance.sol)

pragma lity ^1.2.4;

contract ERC827Base {
  function totalSupply() public view returns (uint256);
  function balanceOf(address who) public view returns (uint256);
  function transfer(address to, uint256 value) public returns (bool);
  function allowance(address owner, address spender) public view returns (uint256);
  function transferFrom(address from, address to, uint256 value) public returns (bool);
  function approve(address spender, uint256 value) public returns (bool);
  event Approval(address indexed owner, address indexed spender, uint256 value);
  event Transfer(address indexed from, address indexed to, uint256 value);
}
contract ERC827Interface is ERC827Base {
  function transferAndCall(address _to, uint256 _value, bytes _data) public payable returns (bool);
  function transferFromAndCall( address _from, address _to, uint256 _value, bytes _data) public payable returns (bool);
  function approveAndCall(address _spender, uint256 _value, bytes _data) public payable returns (bool);
}

Expect output

$ lityc --contract-standard ERC827 erc827_standard.sol

erc827_standard.sol:3:1: Info: Missing 'transferAndCall' with type signature 'function (address,uint256,bytes memory) payable external returns (bool)'. ERC827Base is not compatible to ERC827.
contract ERC827Base {
^ (Relevant source part starts here and spans across multiple lines).
erc827_standard.sol:13:1: Info: ERC827Interface is compatible to ERC827.
contract ERC827Interface is ERC827Base {
^ (Relevant source part starts here and spans across multiple lines).

ERC884 Contract Standard Checker¶

Enable contract standard checker with specific ERC¶

$ lityc --contract-standard ERC884 <contract file>

Examples¶

ERC884 Interface (erc884_interface.sol)

pragma lity ^1.2.4;

contract C20 {
  function totalSupply() public view returns (uint256);
  function balanceOf(address who) public view returns (uint256);
  function transfer(address to, uint256 value) public returns (bool);
  function allowance(address owner, address spender) public view returns (uint256);
  function transferFrom(address from, address to, uint256 value) public returns (bool);
  function approve(address spender, uint256 value) public returns (bool);
  event Approval(address indexed owner, address indexed spender, uint256 value);
  event Transfer(address indexed from, address indexed to, uint256 value);
}
contract ERC884Interface is C20 {
  event VerifiedAddressAdded( address indexed addr, bytes32 hash, address indexed sender);
  event VerifiedAddressRemoved(address indexed addr, address indexed sender);
  event VerifiedAddressUpdated( address indexed addr, bytes32 oldHash, bytes32 hash, address indexed sender);
  event VerifiedAddressSuperseded( address indexed original, address indexed replacement, address indexed sender);
  function addVerified(address addr, bytes32 hash) public;
  function removeVerified(address addr) public;
  function updateVerified(address addr, bytes32 hash) public;
  function cancelAndReissue(address original, address replacement) public;
  function transfer(address to, uint256 value) public returns (bool);
  function transferFrom(address from, address to, uint256 value) public returns (bool);
  function isVerified(address addr) public view returns (bool);
  function isHolder(address addr) public view returns (bool);
  function hasHash(address addr, bytes32 hash) public view returns (bool);
  function holderCount() public view returns (uint);
  function holderAt(uint256 index) public view returns (address);
  function isSuperseded(address addr) public view returns (bool);
  function getCurrentFor(address addr) public view returns (address);
}

Expect output

$ lityc --contract-standard ERC884 erc884_standard.sol

erc884_standard.sol:3:1: Info: Missing 'VerifiedAddressAdded' with type signature 'function (address,bytes32,address)'. C20 is not compatible to ERC884.
contract C20 {
^ (Relevant source part starts here and spans across multiple lines).
erc884_standard.sol:13:1: Info: ERC884Interface is compatible to ERC884.
contract ERC884Interface is C20 {
^ (Relevant source part starts here and spans across multiple lines).

ERC884 Interface with missing function (missing_function.sol)

pragma lity ^1.2.4;

contract ERC884Interface {
  event Transfer(address indexed _from, address indexed _to, uint256 _tokenId);
  event Approval(address indexed _owner, address indexed _approved, uint256 _tokenId);
  event ApprovalForAll(address indexed _owner, address indexed _operator, bool _approved);
  function balanceOf(address _owner) external view returns (uint256);
  function ownerOf(uint256 _tokenId) external view returns (address);
  function safeTransferFrom(address _from, address _to, uint256 _tokenId, bytes data) external payable;
  function safeTransferFrom(address _from, address _to, uint256 _tokenId) external payable;
  function transferFrom(address _from, address _to, uint256 _tokenId) external; // missing payable
  function approve(address _approved, uint256 _tokenId) external payable;
  function setApprovalForAll(address _operator, bool _approved) external;
  function getApproved(uint256 _tokenId) external view returns (address);
  function isApprovedForAll(address _owner, address _operator) external view returns (bool);
  function supportsInterface(bytes4 interfaceID) external view returns (bool);
}

Expect output

$ lityc --contract-standard ERC884 missing_function.sol

missing_function.sol:3:1: Info: Missing 'VerifiedAddressAdded' with type signature 'function (address,bytes32,address)'. ERC884Interface is not compatible to ERC884.
contract ERC884Interface {
^ (Relevant source part starts here and spans across multiple lines).