ERC827Token.sol

pragma solidity ^0.4.13;

import "./ERC827.sol";
import "../ERC20/StandardToken.sol";

/**
   @title ERC827, an extension of ERC20 token standard

   Implementation the ERC827, following the ERC20 standard with extra
   methods to transfer value and data and execute calls in transfers and
   approvals.
   Uses OpenZeppelin StandardToken.
 */
contract ERC827Token is ERC827, StandardToken {

  /**
     @dev Addition to ERC20 token methods. It allows to
     approve the transfer of value and execute a call with the sent data.

     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 that will spend the funds.
     @param _value The amount of tokens to be spent.
     @param _data ABI-encoded contract call to call `_to` address.

     @return true if the call function was executed successfully
   */
  function approve(address _spender, uint256 _value, bytes _data) public returns (bool) {
    require(_spender != address(this));

    super.approve(_spender, _value);

    require(_spender.call(_data));

    return true;
  }

  /**
     @dev Addition to ERC20 token methods. Transfer tokens to a specified
     address and execute a call with the sent data on the same transaction

     @param _to address The address which you want to transfer to
     @param _value uint256 the amout of tokens to be transfered
     @param _data ABI-encoded contract call to call `_to` address.

     @return true if the call function was executed successfully
   */
  function transfer(address _to, uint256 _value, bytes _data) public returns (bool) {
    require(_to != address(this));

    super.transfer(_to, _value);

    require(_to.call(_data));
    return true;
  }

  /**
     @dev Addition to ERC20 token methods. Transfer tokens from one address to
     another and make a contract call on the same transaction

     @param _from The address which you want to send tokens from
     @param _to The address which you want to transfer to
     @param _value The amout of tokens to be transferred
     @param _data ABI-encoded contract call to call `_to` address.

     @return true if the call function was executed successfully
   */
  function transferFrom(address _from, address _to, uint256 _value, bytes _data) public returns (bool) {
    require(_to != address(this));

    super.transferFrom(_from, _to, _value);

    require(_to.call(_data));
    return true;
  }

  /**
   * @dev Addition to StandardToken methods. Increase the amount of tokens that
   * an owner allowed to a spender and execute a call with the sent data.
   *
   * approve should be called when allowed[_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
   * @param _spender The address which will spend the funds.
   * @param _addedValue The amount of tokens to increase the allowance by.
   * @param _data ABI-encoded contract call to call `_spender` address.
   */
  function increaseApproval(address _spender, uint _addedValue, bytes _data) public returns (bool) {
    require(_spender != address(this));

    super.increaseApproval(_spender, _addedValue);

    require(_spender.call(_data));

    return true;
  }

  /**
   * @dev Addition to StandardToken methods. Decrease the amount of tokens that
   * an owner allowed to a spender and execute a call with the sent data.
   *
   * approve should be called when allowed[_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
   * @param _spender The address which will spend the funds.
   * @param _subtractedValue The amount of tokens to decrease the allowance by.
   * @param _data ABI-encoded contract call to call `_spender` address.
   */
  function decreaseApproval(address _spender, uint _subtractedValue, bytes _data) public returns (bool) {
    require(_spender != address(this));

    super.decreaseApproval(_spender, _subtractedValue);

    require(_spender.call(_data));

    return true;
  }

}