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/// join.sol -- Basic token adapters
// Copyright (C) 2018 Rain <rainbreak@riseup.net>
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero 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 Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program. If not, see <https://www.gnu.org/licenses/>.
pragma solidity >=0.5.0;
import "./lib.sol";
contract GemLike {
function transfer(address,uint) external returns (bool);
function transferFrom(address,address,uint) external returns (bool);
}
contract DSTokenLike {
function mint(address,uint) external;
function burn(address,uint) external;
}
contract VatLike {
function slip(bytes32,address,int) external;
function move(address,address,uint) external;
function flux(bytes32,address,address,uint) external;
}
/*
Here we provide *adapters* to connect the Vat to arbitrary external
token implementations, creating a bounded context for the Vat. The
adapters here are provided as working examples:
- `GemJoin`: For well behaved ERC20 tokens, with simple transfer
semantics.
- `ETHJoin`: For native Ether.
- `DaiJoin`: For connecting internal Dai balances to an external
`DSToken` implementation.
In practice, adapter implementations will be varied and specific to
individual collateral types, accounting for different transfer
semantics and token standards.
Adapters need to implement two basic methods:
- `join`: enter collateral into the system
- `exit`: remove collateral from the system
*/
contract GemJoin is DSNote {
VatLike public vat;
bytes32 public ilk;
GemLike public gem;
constructor(address vat_, bytes32 ilk_, address gem_) public {
vat = VatLike(vat_);
ilk = ilk_;
gem = GemLike(gem_);
}
function join(address usr, uint wad) external note {
require(int(wad) >= 0);
vat.slip(ilk, usr, int(wad));
require(gem.transferFrom(msg.sender, address(this), wad));
}
function exit(address usr, uint wad) external note {
require(wad <= 2 ** 255);
vat.slip(ilk, msg.sender, -int(wad));
require(gem.transfer(usr, wad));
}
}
contract ETHJoin is DSNote {
VatLike public vat;
bytes32 public ilk;
constructor(address vat_, bytes32 ilk_) public {
vat = VatLike(vat_);
ilk = ilk_;
}
function join(address usr) external payable note {
require(int(msg.value) >= 0);
vat.slip(ilk, usr, int(msg.value));
}
function exit(address payable usr, uint wad) external note {
require(int(wad) >= 0);
vat.slip(ilk, msg.sender, -int(wad));
usr.transfer(wad);
}
}
contract DaiJoin is DSNote {
VatLike public vat;
DSTokenLike public dai;
constructor(address vat_, address dai_) public {
vat = VatLike(vat_);
dai = DSTokenLike(dai_);
}
uint constant ONE = 10 ** 27;
function mul(uint x, uint y) internal pure returns (uint z) {
require(y == 0 || (z = x * y) / y == x);
}
function join(address usr, uint wad) external note {
vat.move(address(this), usr, mul(ONE, wad));
dai.burn(msg.sender, wad);
}
function exit(address usr, uint wad) external note {
vat.move(msg.sender, address(this), mul(ONE, wad));
dai.mint(usr, wad);
}
}
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