Merge pull request #4 from gryphnft/2.0

2.0

.gitignore

@@ -37,3 +37,4 @@ yarn-error.log*
 #Hardhat files
 cache
 artifacts
+.openzeppelin

contracts/ERC721/ERC721.sol

@@ -2,15 +2,15 @@
 
 pragma solidity ^0.8.0;
 
-import "@openzeppelin/contracts/utils/introspection/ERC165.sol";
+import "@openzeppelin/contracts-upgradeable/utils/introspection/ERC165Upgradeable.sol";
 
-import "@openzeppelin/contracts/token/ERC721/IERC721.sol";
-import "@openzeppelin/contracts/token/ERC721/IERC721Receiver.sol";
-import "@openzeppelin/contracts/token/ERC721/extensions/IERC721Metadata.sol";
+import "@openzeppelin/contracts-upgradeable/token/ERC721/IERC721Upgradeable.sol";
+import "@openzeppelin/contracts-upgradeable/token/ERC721/IERC721ReceiverUpgradeable.sol";
+import "@openzeppelin/contracts-upgradeable/token/ERC721/extensions/IERC721MetadataUpgradeable.sol";
 
-import "@openzeppelin/contracts/utils/Address.sol";
-import "@openzeppelin/contracts/utils/Context.sol";
-import "@openzeppelin/contracts/utils/Strings.sol";
+import "@openzeppelin/contracts-upgradeable/utils/AddressUpgradeable.sol";
+import "@openzeppelin/contracts-upgradeable/utils/ContextUpgradeable.sol";
+import "@openzeppelin/contracts-upgradeable/utils/StringsUpgradeable.sol";
 
 error BalanceQueryZeroAddress();
 error ExistentToken();
@@ -24,16 +24,17 @@ error InvalidAmount();
 error ERC721ReceiverNotReceived();
 error TransferFromNotOwner();
 
-abstract contract ERC721 is Context, ERC165, IERC721, IERC721Metadata {
-  using Address for address;
-  using Strings for uint256;
+abstract contract ERC721 is 
+  ContextUpgradeable, 
+  ERC165Upgradeable, 
+  IERC721Upgradeable, 
+  IERC721MetadataUpgradeable 
+{
+  using AddressUpgradeable for address;
+  using StringsUpgradeable for uint256;
 
   // ============ Storage ============
 
-  // Token name
-  string private _name;
-  // Token symbol
-  string private _symbol;
   // Total supply
   uint256 private _totalSupply;
 
@@ -61,17 +62,6 @@ abstract contract ERC721 is Context, ERC165, IERC721, IERC721Metadata {
     _;
   }
 
-  // ============ Deploy ============
-
-  /**
-   * @dev Initializes the contract by setting a `name` and a `symbol` 
-   * to the token collection.
-   */
-  constructor(string memory name_, string memory symbol_) {
-    _name = name_;
-    _symbol = symbol_;
-  }
-
   // ============ Read Methods ============
 
   /**
@@ -84,13 +74,6 @@ abstract contract ERC721 is Context, ERC165, IERC721, IERC721Metadata {
     return _balances[owner];
   }
 
-  /**
-   * @dev See {IERC721Metadata-name}.
-   */
-  function name() public view virtual override returns(string memory) {
-    return _name;
-  }
-
   /**
    * @dev See {IERC721-ownerOf}.
    */
@@ -104,20 +87,17 @@ abstract contract ERC721 is Context, ERC165, IERC721, IERC721Metadata {
    * @dev See {IERC165-supportsInterface}.
    */
   function supportsInterface(bytes4 interfaceId) 
-    public view virtual override(ERC165, IERC165) returns(bool) 
+    public 
+    view 
+    virtual 
+    override(ERC165Upgradeable, IERC165Upgradeable) 
+    returns(bool) 
   {
     return
-      interfaceId == type(IERC721).interfaceId ||
-      interfaceId == type(IERC721Metadata).interfaceId ||
+      interfaceId == type(IERC721Upgradeable).interfaceId ||
+      interfaceId == type(IERC721Upgradeable).interfaceId ||
       super.supportsInterface(interfaceId);
   }
-
-  /**
-   * @dev See {IERC721Metadata-symbol}.
-   */
-  function symbol() public view virtual override returns(string memory) {
-    return _symbol;
-  }
 
   /**
    * @dev Shows the overall amount of tokens generated in the contract
@@ -287,10 +267,10 @@ abstract contract ERC721 is Context, ERC165, IERC721, IERC721Metadata {
     uint256 tokenId,
     bytes memory _data
   ) private returns (bool) {
-    try IERC721Receiver(to).onERC721Received(
+    try IERC721ReceiverUpgradeable(to).onERC721Received(
       _msgSender(), from, tokenId, _data
     ) returns (bytes4 retval) {
-      return retval == IERC721Receiver.onERC721Received.selector;
+      return retval == IERC721ReceiverUpgradeable.onERC721Received.selector;
     } catch (bytes memory reason) {
       if (reason.length == 0) {
         revert NotERC721Receiver();

contracts/ERC721/ERC721Upgradable.sol

@@ -0,0 +1,36 @@
+// SPDX-License-Identifier: MIT
+
+pragma solidity ^0.8.0;
+
+import "@openzeppelin/contracts-upgradeable/token/ERC20/IERC20Upgradeable.sol";
+import "@openzeppelin/contracts-upgradeable/token/ERC20/utils/SafeERC20Upgradeable.sol";
+
+import "@openzeppelin/contracts-upgradeable/utils/AddressUpgradeable.sol";
+import "@openzeppelin/contracts-upgradeable/access/OwnableUpgradeable.sol";
+import "@openzeppelin/contracts-upgradeable/security/ReentrancyGuardUpgradeable.sol";
+
+import "@openzeppelin/contracts-upgradeable/proxy/utils/Initializable.sol";
+
+import "./extensions/ERC721Pausable.sol";
+import "./extensions/ERC721URIContract.sol";
+
+abstract contract ERC721Upgradable is 
+  OwnableUpgradeable, 
+  ReentrancyGuardUpgradeable,
+  ERC721Pausable,
+  ERC721URIContract 
+{
+  // ============ Overrides ============
+
+  /**
+   * @dev Describes linear override for `_beforeTokenTransfer` used in 
+   * both `ERC721` and `ERC721Pausable`
+   */
+  function _beforeTokenTransfer(
+    address from,
+    address to,
+    uint256 tokenId
+  ) internal virtual override(ERC721, ERC721Pausable) {
+    super._beforeTokenTransfer(from, to, tokenId);
+  }
+}

contracts/ERC721/extensions/ERC721Burnable.sol

@@ -3,13 +3,12 @@
 pragma solidity ^0.8.0;
 
 import "../ERC721.sol";
-import "@openzeppelin/contracts/utils/Context.sol";
 
 /**
  * @title ERC721 Burnable Token
  * @dev ERC721 Token that can be irreversibly burned (destroyed).
  */
-abstract contract ERC721Burnable is Context, ERC721 {
+abstract contract ERC721Burnable is ContextUpgradeable, ERC721 {
   /**
    * @dev Burns `tokenId`. See {ERC721B-_burn}.
    *

contracts/ERC721/extensions/ERC721Pausable.sol

@@ -3,7 +3,7 @@
 pragma solidity ^0.8.0;
 
 import "../ERC721.sol";
-import "@openzeppelin/contracts/security/Pausable.sol";
+import "@openzeppelin/contracts-upgradeable/security/PausableUpgradeable.sol";
 
 error TransferWhilePaused();
 
@@ -14,7 +14,7 @@ error TransferWhilePaused();
  * period, or having an emergency switch for freezing all token transfers in the
  * event of a large bug.
  */
-abstract contract ERC721Pausable is Pausable, ERC721 {
+abstract contract ERC721Pausable is PausableUpgradeable, ERC721 {
   /**
    * @dev See {ERC721B-_beforeTokenTransfer}.
    *