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openzeppelin-contracts/contracts/utils/cryptography/Hashes.sol

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951 B

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
/**
* @dev Library of standard hash functions.
*/
library Hashes {
/**
* @dev Commutative Keccak256 hash of a sorted pair of bytes32. Frequently used when working with merkle proofs.
*
* NOTE: Equivalent to the `standardNodeHash` in our https://github.com/OpenZeppelin/merkle-tree[JavaScript library].
*/
function commutativeKeccak256(bytes32 a, bytes32 b) internal pure returns (bytes32) {
return a < b ? _efficientKeccak256(a, b) : _efficientKeccak256(b, a);
}
/**
* @dev Implementation of keccak256(abi.encode(a, b)) that doesn't allocate or expand memory.
*/
function _efficientKeccak256(bytes32 a, bytes32 b) private pure returns (bytes32 value) {
/// @solidity memory-safe-assembly
assembly {
mstore(0x00, a)
mstore(0x20, b)
value := keccak256(0x00, 0x40)
}
}
}