Hi, my dex final code.
=======
wallet.sol
=======
pragma solidity ^0.8.0;
// import the IERC2O interface
import "../node_modules/@openzeppelin/contracts/token/ERC20/IERC20.sol";
//import safeMath
import "../node_modules/@openzeppelin/contracts/utils/math/SafeMath.sol";
//import Owernable.sol
import "../node_modules/@openzeppelin/contracts/access/Ownable.sol";
contract Wallet is Ownable {
using SafeMath for uint;
using SafeMath for uint256;
// define token struct with token name and address
struct Token {
bytes32 ticker;
address tokenAddress;
}
/*
keep balances of user.
using double mapping to keep track of differnt assets
*/
mapping(address => mapping(bytes32 => uint256)) public balances;
// define a token list to store all supported tokens.
bytes32[] public tokenList;
// define a token mapping to fetch token
mapping(bytes32 => Token) public tokenMapping;
// event is emitted each time a withdraw happens
event withdrawal(
address indexed _to,
bytes32 _ticker,
uint256 indexed _amount
);
modifier tokenExist(bytes32 _ticker) {
//check if token exist
require(
tokenMapping[_ticker].tokenAddress != address(0),
"Token does not exist"
);
_;
}
modifier hasEnoughBalance(uint256 _amount, bytes32 _ticker) {
//check if the user have enough balance to witdraw
require(
balances[msg.sender][_ticker] >= _amount,
"Balance not sufficient"
);
_;
}
function addToken(
bytes32 _ticker,
address _tokenadress
) external onlyOwner {
require(
tokenMapping[_ticker].tokenAddress != _tokenadress,
"Token already exists"
);
//define the new token if non existent
tokenMapping[_ticker] = Token(_ticker, _tokenadress);
tokenList.push(_ticker);
}
/**
*
* deposit _amount of Token named by _ticker into the DEX
* use tranferfrom function of Token contract
* requirements
* Dex needs to receive approval from User in Token Contract
*/
function deposit(
bytes32 _ticker,
uint256 _amount
) external tokenExist(_ticker) {
IERC20 MTK = IERC20(tokenMapping[_ticker].tokenAddress);
require(MTK.balanceOf(msg.sender) >= _amount, "no enough token");
uint256 _currentbalance = balances[msg.sender][_ticker];
(bool success, uint newBalance) = SafeMath.tryAdd(_currentbalance, _amount);
if (success) {
balances[msg.sender][_ticker] = newBalance;
MTK.transferFrom(msg.sender, address(this), _amount);
}
}
/**
* withdraw _amount from this wallet to msg.sender balances into ERC20 Token contract
* requirements
* balance of msg.sender must be greater than or equal to _amount
* use transfer function in ERC20 token contract to transfer from this wallet address to msg.sender address
*/
function withdraw(
bytes32 _ticker,
uint256 _amount
) external tokenExist(_ticker) hasEnoughBalance(_amount, _ticker) {
uint256 _actualBalance = balances[msg.sender][_ticker];
// using Math library to avoid overflow
(bool sucess, uint256 newBalance) = SafeMath.trySub(
_actualBalance,
_amount
);
// if no overflow adjust balances
if (sucess) {
balances[msg.sender][_ticker] = newBalance;
IERC20(tokenMapping[_ticker].tokenAddress).transfer(
msg.sender,
_amount
);
}
}
}
=========
token.sol
=========
pragma solidity ^0.8.0;
// import the IERC2O interface
import "../node_modules/@openzeppelin/contracts/token/ERC20/ERC20.sol";
contract MTK is ERC20 {
constructor() ERC20("mytoken", "MTK") {
_mint(msg.sender, 1000);
}
}
=======
dex.sol
=======
pragma solidity ^0.8.0;
import "./Wallet.sol";
contract Dex is Wallet {
// Enum that describe wheter the order is a SELL or BUY order
enum Side {
BUY,
SELL
}
struct Trader {
address account ;
uint256 share;
}
/**
* Order Struct used to describe an order
*
*/
struct Order {
uint id;
uint position;
Side side;
bytes32 ticker;
uint256 amount;
uint256 price;
bool filled;
}
/**
* used to track the share a trader have in each order
*
*
**/
struct Ordermap{
Trader[] traders;
mapping(address => uint256) indexes;
}
// used to initialize the order ID
uint256 orderID = 0;
/**
* used to fetch orders from the order book
* need the ticker and the side of the order
*/
mapping(bytes32 => mapping(uint => Order[])) public orderbook;
// map an order to the involved traders
mapping(uint => Ordermap) orderTotradersmapping;
/**
* used to synchronize amount on buy side based on the price
*
*/
modifier checkbalances(bytes32 _ticker,Side side, uint256 _amount, uint256 _price){
if (side == Side.BUY) {
(, uint256 price) = SafeMath.tryMul(_amount, _price);
require(
balances[msg.sender][bytes32("ETH")] >= price,
"balance no sufficient"
);
} else if (side == Side.SELL) {
require(
balances[msg.sender][_ticker] >= _amount,
"no Enough tokens"
);
}
_;
}
/**
* used to set the user Ether balance
* is a public payable function
*/
function depositEther() public payable {
balances[msg.sender][bytes32("ETH")] += msg.value;
}
function createMarketOrder(uint256 _amount, bytes32 _ticker, Side side) public {
uint otherside = 0;
if (side == Side.BUY) {
otherside = 1;
}
if (side == Side.SELL) {
require(balances[msg.sender][_ticker] >= _amount, "Token balance not sufficient");
otherside = 0;
}
uint256 r_amount = _amount;
uint256 counter = 0;
Order[] storage orders = orderbook[_ticker][otherside];
if(orders.length==0){
return ;
}
while (r_amount > 0 && counter < orders.length) {
r_amount = _marketOrderTrade(r_amount, _ticker,orders[counter],otherside);
counter++;
}
}
function _marketOrderTrade( uint256 _amount, bytes32 _ticker, Order storage order,uint _otherside) private returns (uint256 remaining) {
uint256 traded = 0;
// if side is buy i.e otherside == 1 ; msg.sender want to buy _amount token from order.traders
// if side is sell i.e otherside == 0; msg.sender want to sell _amount token to order.traders
if (_otherside == 1) {
uint i=0;
//get the list of the buyers
Trader[] storage buyers = orderTotradersmapping[order.id].traders;
while(i <buyers.length && traded<_amount){
uint256 tradable = getTradable(order.amount,buyers[i].share);
_buy(buyers[i],_ticker,tradable, order.price);
(,traded) = SafeMath.tryAdd(traded,tradable);
(,order.amount) = SafeMath.trySub(order.amount,tradable);
i++;
}
}else if(_otherside == 0){
uint j=0;
//get the list of sellers
Trader[] storage sellers = orderTotradersmapping[order.id].traders;
while(j <sellers.length && traded<_amount){
uint256 tradable = getTradable(order.amount,sellers[j].share);
_sell(sellers[j],_ticker,tradable, order.price);
(,traded) = SafeMath.tryAdd(traded,tradable);
j++;
}
}
(,remaining) = SafeMath.trySub(_amount,traded);
return remaining;
}
function _buy(Trader storage _from, bytes32 _ticker, uint256 _amount,uint256 price) private {
// Estimate the price in ETH for the trade for each order on the sell side
(bool success, uint256 due) = SafeMath.tryMul(price, _amount);
// require the buy must have enough ETH to proceed to the trade
require(balances[msg.sender][bytes32("ETH")] >= due,"ETH balance not sufficient for this Buy Market Order ");
if (success) {
// decrease the ETH balance of the buyer
(, balances[msg.sender][bytes32("ETH")]) = SafeMath.trySub(balances[msg.sender][bytes32("ETH")], due);
// increase the ETH balance of the trader on the SELL side
(, balances[_from.account][bytes32("ETH")]) = SafeMath.tryAdd(balances[_from.account][bytes32("ETH")], due);
// decrease the Token balance of the trader on the SELL side
(, balances[_from.account][_ticker]) = SafeMath.trySub(balances[_from.account][_ticker], _amount);
// transfer the token to Buyer
(, balances[msg.sender][_ticker]) = SafeMath.tryAdd(balances[msg.sender][_ticker], _amount);
// adjust trader share
(,_from.share) = SafeMath.trySub(_from.share, _amount);
}
}
function _sell(Trader storage _to, bytes32 _ticker, uint256 _amount,uint256 price) private {
// get the estimate eth due by the trader on the buy side for each order to process
(bool success, uint256 due) = SafeMath.tryMul(_amount, price);
if (success) {
// decrease ETH balance of the trader on the buy side
(, balances[_to.account][bytes32("ETH")]) = SafeMath.trySub(balances[_to.account][bytes32("ETH")], due);
// Increase seller ETH balance
(, balances[msg.sender][bytes32("ETH")]) = SafeMath.tryAdd(balances[msg.sender][bytes32("ETH")],due);
//decrease seller token balance
(, balances[msg.sender][_ticker]) = SafeMath.trySub(balances[msg.sender][_ticker], _amount);
//transfer token to the trader on the buy side
(, balances[_to.account][_ticker]) = SafeMath.tryAdd(balances[_to.account][_ticker],_amount);
(,_to.share) = SafeMath.trySub(_to.share, _amount);
}
}
function _trade(bytes32 ticker,Trader storage buyer, Trader storage seller,uint256 price,uint256 _amount) private {
(bool success, uint256 due) = SafeMath.tryMul(_amount, price);
//require(balances[buyer.trader]["ETH"]>=due, "Balance not enough");
if(success){
(,balances[buyer.account]["ETH"]) = SafeMath.trySub(balances[buyer.account]["ETH"],due);
(,balances[seller.account]["ETH"]) = SafeMath.tryAdd(balances[seller.account]["ETH"],due);
(,balances[seller.account][ticker]) = SafeMath.trySub(balances[seller.account][ticker],_amount);
(,balances[buyer.account][ticker]) = SafeMath.tryAdd(balances[buyer.account][ticker],_amount);
(,buyer.share) = SafeMath.trySub(buyer.share, _amount);
(,seller.share) = SafeMath.trySub(seller.share, _amount);
}
}
/**
* @param _amount the amount of token
*
*
*
*/
function createLimitOrder(uint256 _amount, uint256 _price, bytes32 _ticker,Side side) public checkbalances(_ticker,side,_amount,_price){
Order[] storage orders = orderbook[_ticker][uint(side)];
(uint position, bool exist) = _lookfor(_ticker,_price, side);
Order storage currentOrder;
if(exist){
currentOrder = orders[position];
addTraderToOrder(currentOrder, _amount);
}else{
orders.push( Order({id: orderID, position: orders.length, side: side,ticker: _ticker, amount: _amount, price: _price, filled: false }));
// store the new added Order
currentOrder = orders[orders.length-1];
// create a Trader struct to store informations about the buyer
Trader memory trader = Trader(msg.sender, _amount);
// link the order to the Trader with orderTotradersmapping
orderTotradersmapping[currentOrder.id].traders.push(trader);
orderTotradersmapping[currentOrder.id].indexes[trader.account] = orderTotradersmapping[orderID].traders.length;
}
//sort the orderbook
_quicksort(orders,0, orders.length, side);
orderID++;
if(currentOrder.side == Side.BUY){
(uint index, bool exist) = _lookfor(_ticker, _price,Side.SELL);
if(exist){
_processLimitOrder(currentOrder,orderbook[_ticker][uint(Side.SELL)][index]);
}
// proceed the limit orders if a matching is founded
} else if(currentOrder.side == Side.SELL){
(uint index, bool exist) = _lookfor(_ticker, _price,Side.BUY);
if(exist){
_processLimitOrder(orderbook[_ticker][uint(Side.BUY)][index],currentOrder);
}
}
}
// we use a _quicksort(_tosort, low, high); algorithm to sort orders
function _quicksort(Order[] storage _tosort, uint low, uint high,Side _side) private {
if (low < high) {
uint256 pivot = partition(_tosort, low, high, _side);
_quicksort(_tosort, low, pivot, _side);
_quicksort(_tosort, pivot + 1, high, _side);
}
}
function addTraderToOrder(Order storage current,uint256 _amount) private{
uint256 trader_index = orderTotradersmapping[current.id].indexes[msg.sender];
// trader_index == 0 mean the trader does not have any shares in the order
if(trader_index == 0){
// add the buyer to trader list
orderTotradersmapping[current.id].traders.push(Trader(msg.sender,_amount));
orderTotradersmapping[current.id].indexes[msg.sender] = orderTotradersmapping[current.id].traders.length;
(, current.amount) = SafeMath.tryAdd(current.amount, _amount);
}// trader already have a share in the order
else if(trader_index >0){
(,orderTotradersmapping[current.id].traders[trader_index-1].share) = SafeMath.tryAdd(orderTotradersmapping[current.id].traders[trader_index-1].share, _amount);
(, current.amount) = SafeMath.tryAdd(current.amount, _amount);
}
}
function _lookfor(bytes32 _ticker, uint256 _price,Side side) private view returns(uint index, bool found){
Order[] storage tolookup = orderbook[_ticker][uint(side)];
for(uint i=0; i<tolookup.length; i++){
if((tolookup[i].ticker ==_ticker)&&(tolookup[i].price == _price)){
index = i;
found = true;
return (index, found);
}
}
return (0, false);
}
function _processLimitOrder(Order storage current, Order storage matching) private {
uint256 tradable = getTradable(current.amount, matching.amount);
Trader[] storage buyers = orderTotradersmapping[current.id].traders;
Trader[] storage sellers = orderTotradersmapping[matching.id].traders;
uint i=0;
uint j=0;
while(tradable >0){
if(i >= buyers.length){
return;
}
if(j >= sellers.length){
return;
}
if(buyers[i].share < sellers[j].share){
uint256 trade_amount = buyers[i].share;
_trade(current.ticker, buyers[i],sellers[j],current.price,trade_amount);
(, tradable) = SafeMath.trySub(tradable,trade_amount);
(,current.amount) = SafeMath.trySub(current.amount, trade_amount);
(,matching.amount) = SafeMath.trySub(matching.amount,trade_amount);
i++;
}else if(buyers[i].share > sellers[j].share){
uint256 trade_amount = sellers[i].share;
_trade(current.ticker,buyers[i],sellers[j],current.price,trade_amount);
(, tradable) = SafeMath.trySub(tradable,trade_amount);
(,current.amount) = SafeMath.trySub(current.amount,trade_amount);
(,matching.amount) = SafeMath.trySub(matching.amount,trade_amount);
j++;
}else{
uint256 trade_amount = buyers[i].share;
_trade(current.ticker, buyers[i],sellers[j],current.price,trade_amount);
(, tradable) = SafeMath.trySub(tradable,trade_amount);
(,current.amount) = SafeMath.trySub(current.amount, trade_amount);
(,matching.amount) = SafeMath.trySub(matching.amount,trade_amount);
i++;
j++;
}
}
if(current.amount == 0){
_deleteFromOrderBook(current);
}
if(matching.amount == 0){
_deleteFromOrderBook(matching);
}
}
// partition functions returns the
function partition(Order[] storage arr, uint low, uint high,Side _side) private returns (uint256 index) {
Order memory pivot = arr[low];
uint i = low;
uint j = high - 1;
while (true) {
//sort descending
if (_side == Side.BUY) {
while (arr[i].price > pivot.price) {
i++;
}
while (arr[j].price < pivot.price) {
j--;
}
} else if (_side == Side.SELL) {
//sort ascending
while (arr[i].price < pivot.price) {
i++;
}
while (arr[j].price > pivot.price) {
j--;
}
if (i >= j) {
return j;
}
}
if (i >= j) {
return j;
}
Order memory temp = arr[i];
arr[j].position = i;
arr[i] = arr[j];
temp.position = j;
arr[j] = temp;
}
}
function getTradable(uint256 first, uint256 second) private pure returns(uint256){
if(first>second){
return first;
}
return second;
}
function _deleteFromOrderBook(Order storage _todelete) private {
require(orderbook[_todelete.ticker][uint(_todelete.side)].length > 0," orderbook not empty");
Order[] storage orders = orderbook[_todelete.ticker][uint(_todelete.side)];
if(_todelete.position == orders.length-1){
orders.pop();
return;
}
Order memory toremove = orders[_todelete.position];
orders[_todelete.position] = orders[orders.length-1];
orders[orders.length-1] = toremove;
orders.pop();
delete orderTotradersmapping[_todelete.id];
}
function getOrderbook(bytes32 _ticker,Side side) public view returns (Order[] memory) {
return orderbook[_ticker][uint(side)];
}
}
). Here is my attempt. I will share a web interface later to interact with my dex.