initial commit

hardhat/.gitignore

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+node_modules
+.env
+coverage
+coverage.json
+typechain
+typechain-types
+
+#Hardhat files
+cache
+artifacts
+

hardhat/README.md

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+# Sample Hardhat Project
+
+This project demonstrates a basic Hardhat use case. It comes with a sample contract, a test for that contract, and a script that deploys that contract.
+
+Try running some of the following tasks:
+
+```shell
+npx hardhat help
+npx hardhat test
+GAS_REPORT=true npx hardhat test
+npx hardhat node
+npx hardhat run scripts/deploy.js
+```

hardhat/contracts/Whitelist.sol

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+//SPDX-License-Identifier: Unlicense
+pragma solidity ^0.8.0;
+
+error ONLY_OWNER_CAN_ACT();
+error ALREADY_MEMBER();
+
+contract Whitelist {
+    // Create a mapping of whitelistedAddresses
+    // if an address is whitelisted, we would set it to true, it is false by default for all other addresses.
+    mapping(address => bool) public whitelistedAddresses;
+
+    // numAddressesWhitelisted would be used to keep track of how many addresses have been whitelisted
+    uint16 public numAddressesWhitelisted; // 65,536
+    address public owner;
+
+    constructor(address _ownerAddr) {
+        owner = _ownerAddr;
+    }
+
+    modifier onlyOwner() {
+        if (msg.sender != owner) {
+            revert ONLY_OWNER_CAN_ACT();
+        }
+        _;
+    }
+
+    /**
+        addAddressToWhitelist - This function adds the address of the sender to the
+        whitelist
+     */
+    function addAddressToWhitelist(address _address) public onlyOwner {
+        if (whitelistedAddresses[_address]) {
+            revert ALREADY_MEMBER();
+        }
+        whitelistedAddresses[_address] = true;
+        // Increase the number of whitelisted addresses
+        numAddressesWhitelisted += 1;
+    }
+}

hardhat/hardhat.config.js

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+require("@nomiclabs/hardhat-waffle");
+require("@nomiclabs/hardhat-etherscan");
+require("dotenv").config({ path: ".env" });
+
+const ALCHEMY_API_KEY_URL = process.env.ALCHEMY_API_KEY_URL;
+
+const MUMBAI_PRIVATE_KEY = process.env.MUMBAI_PRIVATE_KEY;
+
+const POLYGONSCAN_KEY = process.env.POLYGONSCAN_KEY;
+
+module.exports = {
+  solidity: "0.8.4",
+  networks: {
+    mumbai: {
+      url: ALCHEMY_API_KEY_URL,
+      accounts: [MUMBAI_PRIVATE_KEY],
+    },
+  },
+  etherscan: {
+    apiKey: {
+      polygonMumbai: POLYGONSCAN_KEY,
+    },
+  },
+};