Split up solidity files and added README

README.md

@@ -0,0 +1,14 @@
+# DEXag Trader
+
+This repo contains a daemon that monitors the CoW Protocol orderbook and, for each new order, simulates trading the order amounts on various DEX aggregators.
+The simulation records both the expected traded amounts as well as the actual executed amounts.
+
+## Simulation Details
+
+Simulation is done with an `eth_call` with state overrides.
+This allows simulations to work even for traders that haven't approved the required contracts.
+
+## Output
+
+The daemon writes to an SQLite database `orders.db`.
+It includes details of the original CoW Protocol order and trade simulation results for each DEX aggregator.

contracts/Trader.sol

@@ -1,33 +1,9 @@
 // SPDX-License-Identifier: MIT
 pragma solidity ^0.8;
 
-library Caller {
-    function doCall(address self, bytes memory cdata) internal returns (bytes memory rdata) {
-        bool success;
-        (success, rdata) = self.call(cdata);
-        if (!success) {
-            assembly { revert(add(rdata, 32), mload(rdata)) }
-        }
-    }
-}
-
-interface IERC20 {
-    function balanceOf(address holder) external view returns (uint256);
-    function approve(address target, uint256 amount) external returns (bool);
-}
-
-library SafeERC20 {
-    using Caller for address;
-
-    function safeApprove(IERC20 self, address target, uint256 amount) internal {
-        bytes memory cdata = abi.encodeCall(self.approve, (target, amount));
-        bytes memory rdata = address(self).doCall(cdata);
-        require(
-            rdata.length == 0 || abi.decode(rdata, (bool)),
-            "SafeERC20: approval failed"
-        );
-    }
-}
+import { IERC20 } from "./interfaces/IERC20.sol";
+import { Caller } from "./libraries/Caller.sol";
+import { SafeERC20 } from "./libraries/SafeERC20.sol";
 
 contract Trader {
     using Caller for address;

contracts/interfaces/IERC20.sol

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+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8;
+
+interface IERC20 {
+    function balanceOf(address holder) external view returns (uint256);
+    function approve(address target, uint256 amount) external returns (bool);
+}

contracts/libraries/Caller.sol

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+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8;
+
+library Caller {
+    function doCall(address self, bytes memory cdata) internal returns (bytes memory rdata) {
+        bool success;
+        (success, rdata) = self.call(cdata);
+        if (!success) {
+            assembly { revert(add(rdata, 32), mload(rdata)) }
+        }
+    }
+}

contracts/libraries/SafeERC20.sol

@@ -0,0 +1,18 @@
+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8;
+
+import { IERC20 } from "../interfaces/IERC20.sol";
+import { Caller } from "./Caller.sol";
+
+library SafeERC20 {
+    using Caller for address;
+
+    function safeApprove(IERC20 self, address target, uint256 amount) internal {
+        bytes memory cdata = abi.encodeCall(self.approve, (target, amount));
+        bytes memory rdata = address(self).doCall(cdata);
+        require(
+            rdata.length == 0 || abi.decode(rdata, (bool)),
+            "SafeERC20: approval failed"
+        );
+    }
+}