dexorder

lib_openzeppelin_contracts/contracts/proxy/Proxy.sol

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+// SPDX-License-Identifier: MIT
+// OpenZeppelin Contracts (last updated v5.0.0) (proxy/Proxy.sol)
+
+pragma solidity ^0.8.20;
+
+/**
+ * @dev This abstract contract provides a fallback function that delegates all calls to another contract using the EVM
+ * instruction `delegatecall`. We refer to the second contract as the _implementation_ behind the proxy, and it has to
+ * be specified by overriding the virtual {_implementation} function.
+ *
+ * Additionally, delegation to the implementation can be triggered manually through the {_fallback} function, or to a
+ * different contract through the {_delegate} function.
+ *
+ * The success and return data of the delegated call will be returned back to the caller of the proxy.
+ */
+abstract contract Proxy {
+    /**
+     * @dev Delegates the current call to `implementation`.
+     *
+     * This function does not return to its internal call site, it will return directly to the external caller.
+     */
+    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())
+            }
+        }
+    }
+
+    /**
+     * @dev This is a virtual function that should be overridden so it returns the address to which the fallback
+     * function and {_fallback} should delegate.
+     */
+    function _implementation() internal view virtual returns (address);
+
+    /**
+     * @dev Delegates the current call to the address returned by `_implementation()`.
+     *
+     * This function does not return to its internal call site, it will return directly to the external caller.
+     */
+    function _fallback() internal virtual {
+        _delegate(_implementation());
+    }
+
+    /**
+     * @dev Fallback function that delegates calls to the address returned by `_implementation()`. Will run if no other
+     * function in the contract matches the call data.
+     */
+    fallback() external payable virtual {
+        _fallback();
+    }
+}