add Permissions enumerable

Author: Krishang Nadgauda

contracts/feature/Permissions.sol

@@ -12,29 +12,23 @@ contract Permissions is IPermissions, Context {
 
     bytes32 public constant DEFAULT_ADMIN_ROLE = 0x00;
 
-    function grantRole(bytes32 role, address account) external {
-        require(
-            hasRole[getRoleAdmin[role]][_msgSender()],
-            "Not role admin."
-        );
+    function grantRole(bytes32 role, address account) public virtual {
+        _checkRole(getRoleAdmin[role], _msgSender());
 
         hasRole[role][account] = true;
 
         emit RoleGranted(role, account, _msgSender());
     }
 
-    function revokeRole(bytes32 role, address account) external {
-        require(
-            hasRole[getRoleAdmin[role]][_msgSender()],
-            "Not role admin."
-        );
+    function revokeRole(bytes32 role, address account) public virtual {
+        _checkRole(getRoleAdmin[role], _msgSender());
 
         delete hasRole[role][account];
 
         emit RoleRevoked(role, account, _msgSender());
     }
 
-    function renounceRole(bytes32 role, address account) external {
+    function renounceRole(bytes32 role, address account) public virtual {
         require(
             _msgSender() == account,
             "Can only renounce for self"

contracts/feature/PermissionsEnumerable.sol

@@ -0,0 +1,72 @@
+// SPDX-License-Identifier: Apache-2.0
+pragma solidity ^0.8.0;
+
+import "./interface/IPermissionsEnumerable.sol";
+import "./Permissions.sol";
+
+contract PermissionsEnumerable is IPermissionsEnumerable, Permissions  {
+
+    struct RoleMembers {
+        uint256 index;
+        mapping(uint256 => address) members;
+        mapping(address => uint256) indexOf;
+    }
+
+    mapping(bytes32 => RoleMembers) private roleMembers; 
+
+    function getRoleMember(bytes32 role, uint256 index) external view returns (address member) {
+        uint256 currentIndex = roleMembers[role].index;
+        uint256 check;
+
+        for(uint256 i = 0; i < currentIndex; i += 1) {
+            if(roleMembers[role].members[i] != address(0)) {
+                if(check == index) {
+                    member = roleMembers[role].members[i];
+                }
+            } else {
+                check += 1;
+            }
+        }
+        
+    }
+
+    function getRoleMemberCount(bytes32 role) external view returns (uint256 count) {
+        uint256 currentIndex = roleMembers[role].index;
+        
+        for(uint256 i = 0; i < currentIndex; i += 1) {
+            if(roleMembers[role].members[i] != address(0)) {
+                count += 1;
+            }
+        }
+    }
+
+    function grantRole(bytes32 role, address account) public override(IPermissions, Permissions) {
+        super.grantRole(role, account);
+        _addMember(role, account);
+    }
+
+    function revokeRole(bytes32 role, address account) public override(IPermissions, Permissions) {
+        super.revokeRole(role, account);
+        _removeMember(role, account);
+    }
+
+    function renounceRole(bytes32 role, address account) public override(IPermissions, Permissions) {
+        super.renounceRole(role, account);
+        _removeMember(role, account);
+    }
+
+    function _addMember(bytes32 role, address account) internal {        
+        uint256 idx = roleMembers[role].index;
+        roleMembers[role].index += 1;
+
+        roleMembers[role].members[idx] = account;
+        roleMembers[role].indexOf[account] = idx;
+    }
+
+    function _removeMember(bytes32 role, address account) internal {        
+        uint256 idx = roleMembers[role].indexOf[account];
+
+        delete roleMembers[role].members[idx];
+        delete roleMembers[role].indexOf[account];
+    }
+}