Contract Source Code:
File 1 of 1 : DSValue
/// value.sol - a value is a simple thing, it can be get and set
// Copyright (C) 2017 DappHub, LLC
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// You should have received a copy of the GNU General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.
pragma solidity >=0.4.23;
interface DSAuthority {
function canCall(
address src, address dst, bytes4 sig
) external view returns (bool);
}
contract DSAuthEvents {
event LogSetAuthority (address indexed authority);
event LogSetOwner (address indexed owner);
}
contract DSAuth is DSAuthEvents {
DSAuthority public authority;
address public owner;
constructor() public {
owner = msg.sender;
emit LogSetOwner(msg.sender);
}
function setOwner(address owner_)
public
auth
{
owner = owner_;
emit LogSetOwner(owner);
}
function setAuthority(DSAuthority authority_)
public
auth
{
authority = authority_;
emit LogSetAuthority(address(authority));
}
modifier auth {
require(isAuthorized(msg.sender, msg.sig), "ds-auth-unauthorized");
_;
}
function isAuthorized(address src, bytes4 sig) internal view returns (bool) {
if (src == address(this)) {
return true;
} else if (src == owner) {
return true;
} else if (authority == DSAuthority(0)) {
return false;
} else {
return authority.canCall(src, address(this), sig);
}
}
}
pragma solidity >=0.4.23;
contract DSNote {
event LogNote(
bytes4 indexed sig,
address indexed guy,
bytes32 indexed foo,
bytes32 indexed bar,
uint256 wad,
bytes fax
) anonymous;
modifier note {
bytes32 foo;
bytes32 bar;
uint256 wad;
assembly {
foo := calldataload(4)
bar := calldataload(36)
wad := callvalue()
}
_;
emit LogNote(msg.sig, msg.sender, foo, bar, wad, msg.data);
}
}
contract DSMath {
function add(uint x, uint y) internal pure returns (uint z) {
require((z = x + y) >= x, "ds-math-add-overflow");
}
function sub(uint x, uint y) internal pure returns (uint z) {
require((z = x - y) <= x, "ds-math-sub-underflow");
}
function mul(uint x, uint y) internal pure returns (uint z) {
require(y == 0 || (z = x * y) / y == x, "ds-math-mul-overflow");
}
function min(uint x, uint y) internal pure returns (uint z) {
return x <= y ? x : y;
}
function max(uint x, uint y) internal pure returns (uint z) {
return x >= y ? x : y;
}
function imin(int x, int y) internal pure returns (int z) {
return x <= y ? x : y;
}
function imax(int x, int y) internal pure returns (int z) {
return x >= y ? x : y;
}
uint constant WAD = 10 ** 18;
uint constant RAY = 10 ** 27;
//rounds to zero if x*y < WAD / 2
function wmul(uint x, uint y) internal pure returns (uint z) {
z = add(mul(x, y), WAD / 2) / WAD;
}
//rounds to zero if x*y < WAD / 2
function rmul(uint x, uint y) internal pure returns (uint z) {
z = add(mul(x, y), RAY / 2) / RAY;
}
//rounds to zero if x*y < WAD / 2
function wdiv(uint x, uint y) internal pure returns (uint z) {
z = add(mul(x, WAD), y / 2) / y;
}
//rounds to zero if x*y < RAY / 2
function rdiv(uint x, uint y) internal pure returns (uint z) {
z = add(mul(x, RAY), y / 2) / y;
}
// This famous algorithm is called "exponentiation by squaring"
// and calculates x^n with x as fixed-point and n as regular unsigned.
//
// It's O(log n), instead of O(n) for naive repeated multiplication.
//
// These facts are why it works:
//
// If n is even, then x^n = (x^2)^(n/2).
// If n is odd, then x^n = x * x^(n-1),
// and applying the equation for even x gives
// x^n = x * (x^2)^((n-1) / 2).
//
// Also, EVM division is flooring and
// floor[(n-1) / 2] = floor[n / 2].
//
function rpow(uint x, uint n) internal pure returns (uint z) {
z = n % 2 != 0 ? x : RAY;
for (n /= 2; n != 0; n /= 2) {
x = rmul(x, x);
if (n % 2 != 0) {
z = rmul(z, x);
}
}
}
}
contract DSThing is DSAuth, DSNote, DSMath {
function S(string memory s) internal pure returns (bytes4) {
return bytes4(keccak256(abi.encodePacked(s)));
}
}
contract DSValue is DSThing {
bool has;
bytes32 val;
function peek() public view returns (bytes32, bool) {
return (val,has);
}
function read() public view returns (bytes32) {
bytes32 wut; bool haz;
(wut, haz) = peek();
require(haz, "haz-not");
return wut;
}
function poke(bytes32 wut) public note auth {
val = wut;
has = true;
}
function void() public note auth { // unset the value
has = false;
}
}