Single base router (#15)

src/example/RouterImmutable.sol

@@ -3,15 +3,23 @@
 
 pragma solidity ^0.8.0;
 
-import "../presets/BaseRouterWithDefaults.sol";
+import "../presets/BaseRouter.sol";
 
 /**
  *  This smart contract is an EXAMPLE, and is not meant for use in production.
  */
 
-contract RouterImmutable is BaseRouterWithDefaults {
+abstract contract MyRouter is BaseRouter {
+
+    constructor(Extension[] memory _extensions) BaseRouter(_extensions) {
+        // Initialize the router with a set of default extensions.
+        __BaseRouter_init();
+    }
+}
+
+contract RouterImmutable is MyRouter {
 
-    constructor(Extension[] memory _extensions) BaseRouterWithDefaults(_extensions) {}
+    constructor(Extension[] memory _extensions) MyRouter(_extensions) {}
 
     /*///////////////////////////////////////////////////////////////
                             Overrides

src/example/RouterRegistryConstrained.sol

@@ -32,7 +32,7 @@ contract RouterRegistryConstrained is BaseRouter {
     ExtensionRegistry public registry;
 
     /// @dev Cannot initialize with extensions before registry is set, so we pass empty array to base constructor.
-    constructor(address _registry) {
+    constructor(address _registry) BaseRouter(new Extension[](0)) {
         admin = msg.sender;
         registry = ExtensionRegistry(_registry);
     }

src/example/RouterUpgradeable.sol

@@ -4,15 +4,14 @@
 pragma solidity ^0.8.0;
 
 import "../presets/BaseRouter.sol";
-
 /**
  *  This smart contract is an EXAMPLE, and is not meant for use in production.
  */
 contract RouterUpgradeable is BaseRouter {
 
     address public admin;
 
-    constructor() {
+    constructor() BaseRouter(new Extension[](0)) {
         admin = msg.sender;
     }
 

src/lib/BaseRouterStorage.sol

@@ -0,0 +1,25 @@
+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.0;
+
+/// @title BaseRouterStorage
+/// @author thirdweb (https://github.com/thirdweb-dev/dynamic-contracts)
+/// @notice Defined storage for the base router preset.
+
+library BaseRouterStorage {
+
+    /// @custom:storage-location erc7201:base.router.storage
+    bytes32 public constant BASE_ROUTER_STORAGE_POSITION = keccak256(abi.encode(uint256(keccak256("base.router.storage")) - 1));
+
+    struct Data {
+        /// @dev Mapping from default extension name -> whether the extension has been removed or replaced at least once.
+        mapping(string => bool) isRemovedOrReplaced;
+    }
+
+    /// @dev Returns access to the extension manager's storage.
+    function data() internal pure returns (Data storage data_) {
+        bytes32 position = BASE_ROUTER_STORAGE_POSITION;
+        assembly {
+            data_.slot := position
+        }
+    }
+}

src/presets/BaseRouter.sol

@@ -1,20 +1,56 @@
 // SPDX-License-Identifier: MIT
 pragma solidity ^0.8.0;
 
-import "../core/Router.sol";
-import "./ExtensionManager.sol";
+import { Router, IRouter } from "../core/Router.sol";
+import { IRouterState } from "../interface/IRouterState.sol";
+import { IRouterStateGetters } from "../interface/IRouterStateGetters.sol";
+import { ExtensionManager } from "./ExtensionManager.sol";
+import { DefaultExtensionSet } from "./DefaultExtensionSet.sol";
+import { BaseRouterStorage } from "../lib/BaseRouterStorage.sol";
+import { StringSet } from "../lib/StringSet.sol";
 
 /// @title BaseRouter
 /// @author thirdweb (https://github.com/thirdweb-dev/dynamic-contracts)
-/// @notice A preset Router + ExtensionManager.
+/// @notice A router with an API to manage its extensions.
 
 abstract contract BaseRouter is Router, ExtensionManager {
+
+    using StringSet for StringSet.Set;
+
+    /// @notice The address where the router's default extension set is stored.
+    address public immutable defaultExtensions;
 
-    /**
-	 *	@notice Returns the implementation address to delegateCall for the given function selector.
-	 *	@param _functionSelector The function selector to get the implementation address for.
-	 *	@return implementation The implementation address to delegateCall for the given function selector.
-	 */
+    /// @notice Initialize the Router with a set of default extensions.
+    constructor(Extension[] memory _extensions) {
+        address defaultExtensionsAddr = _extensions.length > 0 ? address(new DefaultExtensionSet(_extensions)) : address(0);
+        defaultExtensions = defaultExtensionsAddr;
+    }
+
+    /// @notice Initialize the Router with a set of default extensions.
+    function __BaseRouter_init() internal {
+        Extension[] memory defaults = IRouterState(defaultExtensions).getAllExtensions();
+
+        for(uint256 i = 0; i < defaults.length; i += 1) {
+
+            Extension memory extension = defaults[i];
+            // Store: new extension name.
+            require(_extensionManagerStorage().extensionNames.add(extension.metadata.name), "ExtensionManager: extension already exists.");
+
+            // 1. Store: metadata for extension.
+            _setMetadataForExtension(extension.metadata.name, extension.metadata);
+            uint256 len = extension.functions.length;
+            for (uint256 j = 0; j < len; j += 1) {
+                // 2. Store: function for extension.
+                _addToFunctionMap(extension.metadata.name, extension.functions[j]);
+                // 3. Store: metadata for function.
+                _setMetadataForFunction(extension.functions[j].functionSelector, extension.metadata);
+            }
+
+            emit ExtensionAdded(extension.metadata.name, extension.metadata.implementation, extension);
+        }
+    }
+
+    /// @notice Returns the implementation contract address for a given function signature.
     function getImplementationForFunction(bytes4 _functionSelector) public view virtual override returns (address) {
         return getMetadataForFunction(_functionSelector).implementation;
     }