Erc1537

contracts/ERC1537.sol

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+
+/**
+ * Copyright (c) 2018-present, Leap DAO (leapdao.org)
+ *
+ * This source code is licensed under the Mozilla Public License, version 2,
+ * found in the LICENSE file in the root directory of this source tree.
+ */
+
+pragma solidity ^0.5.2;
+
+import "openzeppelin-solidity/contracts/token/ERC721/ERC721.sol";
+import "./IERC1537.sol";
+
+contract ERC1537 is IERC1537, ERC721 {
+
+  mapping(uint256 => bytes32) data;
+
+  function mint(address _to, uint256 _tokenId) public {
+    super._mint(_to, _tokenId);
+  }
+
+  function burn(uint256 _tokenId) public {
+    super._burn(ownerOf(_tokenId), _tokenId);
+    delete(data[_tokenId]);
+  }
+
+  function readData(uint256 _tokenId) public view returns (bytes32) {
+    require(_exists(_tokenId));
+    return data[_tokenId];
+  }
+
+  function writeData(uint256 _tokenId, bytes32 _newData) public {
+    require(msg.sender == ownerOf(_tokenId));
+    emit DataUpdated(_tokenId, data[_tokenId], _newData);
+    data[_tokenId] = _newData;
+  }
+
+}

contracts/IERC1537.sol

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+
+/**
+ * Copyright (c) 2018-present, Leap DAO (leapdao.org)
+ *
+ * This source code is licensed under the Mozilla Public License, version 2,
+ * found in the LICENSE file in the root directory of this source tree.
+ */
+
+pragma solidity ^0.5.2;
+
+contract IERC1537 {
+
+  event DataUpdated(uint256 indexed tokenId, bytes32 oldData, bytes32 newData);
+
+  function readData(uint256 _tokenId) public view returns (bytes32);
+
+  function writeData(uint256 _tokenId, bytes32 _newData) public;
+
+}

test/erc1537.js

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+const ERC1537 = artifacts.require('./ERC1537.sol');
+
+require('./helpers/setup');
+
+contract('ERC1537', (accounts) => {
+  const firstTokenId = 100;
+  const creator = accounts[0];
+  const empty = '0x0000000000000000000000000000000000000000000000000000000000000000';
+  const data = '0x0101010101010101010101010101010101010101010101010101010101010101';
+  let dataToken;
+
+  beforeEach(async () => {
+    dataToken = await ERC1537.new();
+    await dataToken.mint(creator, firstTokenId);
+  });
+
+  it('should allow read write read', async () => {
+    let rsp = await dataToken.readData(firstTokenId);
+    assert.equal(rsp, empty);
+    await dataToken.writeData(firstTokenId, data);
+    rsp = await dataToken.readData(firstTokenId);
+    assert.equal(rsp, data);
+  });
+
+});