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89 lines
2.6 KiB
Solidity
89 lines
2.6 KiB
Solidity
// SPDX-License-Identifier: MIT
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// OpenZeppelin Contracts (last updated v4.7.0) (utils/StorageSlot.sol)
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pragma solidity ^0.8.0;
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/**
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* @dev Library for reading and writing primitive types to specific storage slots.
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*
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* Storage slots are often used to avoid storage conflict when dealing with upgradeable contracts.
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* This library helps with reading and writing to such slots without the need for inline assembly.
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*
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* The functions in this library return Slot structs that contain a `value` member that can be used to read or write.
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*
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* Example usage to set ERC1967 implementation slot:
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* ```
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* contract ERC1967 {
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* bytes32 internal constant _IMPLEMENTATION_SLOT = 0x360894a13ba1a3210667c828492db98dca3e2076cc3735a920a3ca505d382bbc;
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*
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* function _getImplementation() internal view returns (address) {
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* return StorageSlot.getAddressSlot(_IMPLEMENTATION_SLOT).value;
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* }
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*
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* function _setImplementation(address newImplementation) internal {
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* require(Address.isContract(newImplementation), "ERC1967: new implementation is not a contract");
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* StorageSlot.getAddressSlot(_IMPLEMENTATION_SLOT).value = newImplementation;
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* }
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* }
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* ```
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*
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* _Available since v4.1 for `address`, `bool`, `bytes32`, and `uint256`._
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*/
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library StorageSlot {
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struct AddressSlot {
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address value;
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}
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struct BooleanSlot {
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bool value;
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}
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struct Bytes32Slot {
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bytes32 value;
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}
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struct Uint256Slot {
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uint256 value;
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}
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/**
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* @dev Returns an `AddressSlot` with member `value` located at `slot`.
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*/
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function getAddressSlot(bytes32 slot) internal pure returns (AddressSlot storage r) {
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/// @solidity memory-safe-assembly
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assembly {
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r.slot := slot
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}
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}
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/**
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* @dev Returns an `BooleanSlot` with member `value` located at `slot`.
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*/
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function getBooleanSlot(bytes32 slot) internal pure returns (BooleanSlot storage r) {
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/// @solidity memory-safe-assembly
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assembly {
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r.slot := slot
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}
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}
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/**
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* @dev Returns an `Bytes32Slot` with member `value` located at `slot`.
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*/
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function getBytes32Slot(bytes32 slot) internal pure returns (Bytes32Slot storage r) {
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/// @solidity memory-safe-assembly
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assembly {
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r.slot := slot
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}
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}
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/**
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* @dev Returns an `Uint256Slot` with member `value` located at `slot`.
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*/
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function getUint256Slot(bytes32 slot) internal pure returns (Uint256Slot storage r) {
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/// @solidity memory-safe-assembly
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assembly {
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r.slot := slot
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}
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}
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}
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