Add EntrypointOverrideable: opt-in override an extension for a function. (#293)

Author: nkrishang

contracts/extension/interface/plugin/IEntrypointOverrideable.sol

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+// SPDX-License-Identifier: Apache-2.0
+pragma solidity ^0.8.0;
+
+interface IEntrypointOverrideable {
+    struct ExtensionMap {
+        bytes4 selector;
+        address extension;
+    }
+
+    function overrideExtensionForFunction(bytes4 _selector, address _extension) external;
+
+    function getAllOverriden() external view returns (ExtensionMap[] memory functionExtensionPairs);
+}

contracts/extension/plugin/EntrypointOverrideable.sol

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+// SPDX-License-Identifier: Apache-2.0
+pragma solidity ^0.8.0;
+
+import "../interface/plugin/IMap.sol";
+import "../interface/plugin/IEntrypointOverrideable.sol";
+import "../../extension/Multicall.sol";
+import "../../openzeppelin-presets/utils/EnumerableSet.sol";
+
+library EntrypointOverrideableStorage {
+    bytes32 public constant ENTRYPOINT_OVERRIDEABLE_STORAGE_POSITION = keccak256("entrypoint.overrideable.storage");
+
+    struct Data {
+        EnumerableSet.Bytes32Set functions;
+        mapping(bytes4 => address) extensionOverride;
+    }
+
+    function entrypointStorage() internal pure returns (Data storage entrypointData) {
+        bytes32 position = ENTRYPOINT_OVERRIDEABLE_STORAGE_POSITION;
+        assembly {
+            entrypointData.slot := position
+        }
+    }
+}
+
+abstract contract EntrypointOverrideable is Multicall, IEntrypointOverrideable {
+    using EnumerableSet for EnumerableSet.Bytes32Set;
+
+    /*///////////////////////////////////////////////////////////////
+                            State variables
+    //////////////////////////////////////////////////////////////*/
+
+    address public immutable functionMap;
+
+    /*///////////////////////////////////////////////////////////////
+                    Constructor + initializer logic
+    //////////////////////////////////////////////////////////////*/
+
+    constructor(address _functionMap) {
+        functionMap = _functionMap;
+    }
+
+    /*///////////////////////////////////////////////////////////////
+                        Generic contract logic
+    //////////////////////////////////////////////////////////////*/
+
+    fallback() external payable virtual {
+        address extension = _getExtensionOverride(msg.sig);
+        if (extension == address(0)) {
+            extension = IMap(functionMap).getExtensionForFunction(msg.sig);
+        }
+
+        _delegate(extension);
+    }
+
+    receive() external payable {}
+
+    function _delegate(address implementation) internal virtual {
+        assembly {
+            // Copy msg.data. We take full control of memory in this inline assembly
+            // block because it will not return to Solidity code. We overwrite the
+            // Solidity scratch pad at memory position 0.
+            calldatacopy(0, 0, calldatasize())
+
+            // Call the implementation.
+            // out and outsize are 0 because we don't know the size yet.
+            let result := delegatecall(gas(), implementation, 0, calldatasize(), 0, 0)
+
+            // Copy the returned data.
+            returndatacopy(0, 0, returndatasize())
+
+            switch result
+            // delegatecall returns 0 on error.
+            case 0 {
+                revert(0, returndatasize())
+            }
+            default {
+                return(0, returndatasize())
+            }
+        }
+    }
+
+    /*///////////////////////////////////////////////////////////////
+                        External functions
+    //////////////////////////////////////////////////////////////*/
+
+    function overrideExtensionForFunction(bytes4 _selector, address _extension) external {
+        require(_canOverrideExtensions(), "Entrypoint: cannot override extensions.");
+
+        EntrypointOverrideableStorage.Data storage data = EntrypointOverrideableStorage.entrypointStorage();
+        data.extensionOverride[_selector] = _extension;
+
+        if (_extension != address(0)) {
+            data.functions.add(bytes32(_selector));
+        } else {
+            data.functions.remove(bytes32(_selector));
+        }
+    }
+
+    function getAllOverriden() external view returns (ExtensionMap[] memory functionExtensionPairs) {
+        EntrypointOverrideableStorage.Data storage data = EntrypointOverrideableStorage.entrypointStorage();
+        uint256 len = data.functions.length();
+        functionExtensionPairs = new ExtensionMap[](len);
+
+        for (uint256 i = 0; i < len; i += 1) {
+            bytes4 selector = bytes4(data.functions.at(i));
+            functionExtensionPairs[i] = ExtensionMap(selector, data.extensionOverride[selector]);
+        }
+    }
+
+    /*///////////////////////////////////////////////////////////////
+                        Internal functions
+    //////////////////////////////////////////////////////////////*/
+
+    function _getExtensionOverride(bytes4 _selector) internal view returns (address) {
+        EntrypointOverrideableStorage.Data storage data = EntrypointOverrideableStorage.entrypointStorage();
+        return data.extensionOverride[_selector];
+    }
+
+    function _canOverrideExtensions() internal view virtual returns (bool);
+}

docs/EntrypointOverrideable.md

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+# EntrypointOverrideable
+
+
+
+
+
+
+
+
+
+## Methods
+
+### functionMap
+
+```solidity
+function functionMap() external view returns (address)
+```
+
+
+
+
+
+
+#### Returns
+
+| Name | Type | Description |
+|---|---|---|
+| _0 | address | undefined |
+
+### getAllOverriden
+
+```solidity
+function getAllOverriden() external view returns (struct IEntrypointOverrideable.ExtensionMap[] functionExtensionPairs)
+```
+
+
+
+
+
+
+#### Returns
+
+| Name | Type | Description |
+|---|---|---|
+| functionExtensionPairs | IEntrypointOverrideable.ExtensionMap[] | undefined |
+
+### multicall
+
+```solidity
+function multicall(bytes[] data) external nonpayable returns (bytes[] results)
+```
+
+Receives and executes a batch of function calls on this contract.
+
+*Receives and executes a batch of function calls on this contract.*
+
+#### Parameters
+
+| Name | Type | Description |
+|---|---|---|
+| data | bytes[] | The bytes data that makes up the batch of function calls to execute. |
+
+#### Returns
+
+| Name | Type | Description |
+|---|---|---|
+| results | bytes[] | The bytes data that makes up the result of the batch of function calls executed. |
+
+### overrideExtensionForFunction
+
+```solidity
+function overrideExtensionForFunction(bytes4 _selector, address _extension) external nonpayable
+```
+
+
+
+
+
+#### Parameters
+
+| Name | Type | Description |
+|---|---|---|
+| _selector | bytes4 | undefined |
+| _extension | address | undefined |
+
+
+
+

docs/EntrypointOverrideableStorage.md

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+# EntrypointOverrideableStorage
+
+
+
+
+
+
+
+
+
+## Methods
+
+### ENTRYPOINT_OVERRIDEABLE_STORAGE_POSITION
+
+```solidity
+function ENTRYPOINT_OVERRIDEABLE_STORAGE_POSITION() external view returns (bytes32)
+```
+
+
+
+
+
+
+#### Returns
+
+| Name | Type | Description |
+|---|---|---|
+| _0 | bytes32 | undefined |
+
+
+
+

docs/IEntrypointOverrideable.md

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+# IEntrypointOverrideable
+
+
+
+
+
+
+
+
+
+## Methods
+
+### getAllOverriden
+
+```solidity
+function getAllOverriden() external view returns (struct IEntrypointOverrideable.ExtensionMap[] functionExtensionPairs)
+```
+
+
+
+
+
+
+#### Returns
+
+| Name | Type | Description |
+|---|---|---|
+| functionExtensionPairs | IEntrypointOverrideable.ExtensionMap[] | undefined |
+
+### overrideExtensionForFunction
+
+```solidity
+function overrideExtensionForFunction(bytes4 _selector, address _extension) external nonpayable
+```
+
+
+
+
+
+#### Parameters
+
+| Name | Type | Description |
+|---|---|---|
+| _selector | bytes4 | undefined |
+| _extension | address | undefined |
+
+
+
+