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TransferValidation.sol
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TransferValidation.sol
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// SPDX-License-Identifier: MIT
pragma solidity ^0.8.4;
import "@openzeppelin/contracts/utils/Context.sol";
/**
* @title TransferValidation
* @author Limit Break, Inc.
* @notice A mix-in that can be combined with ERC-721 contracts to provide more granular hooks.
* Openzeppelin's ERC721 contract only provides hooks for before and after transfer. This allows
* developers to validate or customize transfers within the context of a mint, a burn, or a transfer.
*/
abstract contract TransferValidation is Context {
error ShouldNotMintToBurnAddress();
/// @dev Inheriting contracts should call this function in the _beforeTokenTransfer function to get more granular hooks.
function _validateBeforeTransfer(address from, address to, uint256 tokenId) internal virtual {
bool fromZeroAddress = from == address(0);
bool toZeroAddress = to == address(0);
if(fromZeroAddress && toZeroAddress) {
revert ShouldNotMintToBurnAddress();
} else if(fromZeroAddress) {
_preValidateMint(_msgSender(), to, tokenId, msg.value);
} else if(toZeroAddress) {
_preValidateBurn(_msgSender(), from, tokenId, msg.value);
} else {
_preValidateTransfer(_msgSender(), from, to, tokenId, msg.value);
}
}
/// @dev Inheriting contracts should call this function in the _afterTokenTransfer function to get more granular hooks.
function _validateAfterTransfer(address from, address to, uint256 tokenId) internal virtual {
bool fromZeroAddress = from == address(0);
bool toZeroAddress = to == address(0);
if(fromZeroAddress && toZeroAddress) {
revert ShouldNotMintToBurnAddress();
} else if(fromZeroAddress) {
_postValidateMint(_msgSender(), to, tokenId, msg.value);
} else if(toZeroAddress) {
_postValidateBurn(_msgSender(), from, tokenId, msg.value);
} else {
_postValidateTransfer(_msgSender(), from, to, tokenId, msg.value);
}
}
/// @dev Optional validation hook that fires before a mint
function _preValidateMint(address caller, address to, uint256 tokenId, uint256 value) internal virtual {}
/// @dev Optional validation hook that fires after a mint
function _postValidateMint(address caller, address to, uint256 tokenId, uint256 value) internal virtual {}
/// @dev Optional validation hook that fires before a burn
function _preValidateBurn(address caller, address from, uint256 tokenId, uint256 value) internal virtual {}
/// @dev Optional validation hook that fires after a burn
function _postValidateBurn(address caller, address from, uint256 tokenId, uint256 value) internal virtual {}
/// @dev Optional validation hook that fires before a transfer
function _preValidateTransfer(address caller, address from, address to, uint256 tokenId, uint256 value) internal virtual {}
/// @dev Optional validation hook that fires after a transfer
function _postValidateTransfer(address caller, address from, address to, uint256 tokenId, uint256 value) internal virtual {}
}