Contract Name:
MerchMintPass
Contract Source Code:
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
/**
* @dev Collection of functions related to the address type
*/
library Address {
/**
* @dev Returns true if `account` is a contract.
*
* [IMPORTANT]
* ====
* It is unsafe to assume that an address for which this function returns
* false is an externally-owned account (EOA) and not a contract.
*
* Among others, `isContract` will return false for the following
* types of addresses:
*
* - an externally-owned account
* - a contract in construction
* - an address where a contract will be created
* - an address where a contract lived, but was destroyed
* ====
*/
function isContract(address account) internal view returns (bool) {
// This method relies on extcodesize, which returns 0 for contracts in
// construction, since the code is only stored at the end of the
// constructor execution.
uint256 size;
assembly {
size := extcodesize(account)
}
return size > 0;
}
/**
* @dev Replacement for Solidity's `transfer`: sends `amount` wei to
* `recipient`, forwarding all available gas and reverting on errors.
*
* https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
* of certain opcodes, possibly making contracts go over the 2300 gas limit
* imposed by `transfer`, making them unable to receive funds via
* `transfer`. {sendValue} removes this limitation.
*
* https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
*
* IMPORTANT: because control is transferred to `recipient`, care must be
* taken to not create reentrancy vulnerabilities. Consider using
* {ReentrancyGuard} or the
* https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
*/
function sendValue(address payable recipient, uint256 amount) internal {
require(address(this).balance >= amount, "Address: insufficient balance");
(bool success, ) = recipient.call{value: amount}("");
require(success, "Address: unable to send value, recipient may have reverted");
}
/**
* @dev Performs a Solidity function call using a low level `call`. A
* plain `call` is an unsafe replacement for a function call: use this
* function instead.
*
* If `target` reverts with a revert reason, it is bubbled up by this
* function (like regular Solidity function calls).
*
* Returns the raw returned data. To convert to the expected return value,
* use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
*
* Requirements:
*
* - `target` must be a contract.
* - calling `target` with `data` must not revert.
*
* _Available since v3.1._
*/
function functionCall(address target, bytes memory data) internal returns (bytes memory) {
return functionCall(target, data, "Address: low-level call failed");
}
/**
* @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
* `errorMessage` as a fallback revert reason when `target` reverts.
*
* _Available since v3.1._
*/
function functionCall(
address target,
bytes memory data,
string memory errorMessage
) internal returns (bytes memory) {
return functionCallWithValue(target, data, 0, errorMessage);
}
/**
* @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
* but also transferring `value` wei to `target`.
*
* Requirements:
*
* - the calling contract must have an ETH balance of at least `value`.
* - the called Solidity function must be `payable`.
*
* _Available since v3.1._
*/
function functionCallWithValue(
address target,
bytes memory data,
uint256 value
) internal returns (bytes memory) {
return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
}
/**
* @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
* with `errorMessage` as a fallback revert reason when `target` reverts.
*
* _Available since v3.1._
*/
function functionCallWithValue(
address target,
bytes memory data,
uint256 value,
string memory errorMessage
) internal returns (bytes memory) {
require(address(this).balance >= value, "Address: insufficient balance for call");
require(isContract(target), "Address: call to non-contract");
(bool success, bytes memory returndata) = target.call{value: value}(data);
return _verifyCallResult(success, returndata, errorMessage);
}
/**
* @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
* but performing a static call.
*
* _Available since v3.3._
*/
function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
return functionStaticCall(target, data, "Address: low-level static call failed");
}
/**
* @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
* but performing a static call.
*
* _Available since v3.3._
*/
function functionStaticCall(
address target,
bytes memory data,
string memory errorMessage
) internal view returns (bytes memory) {
require(isContract(target), "Address: static call to non-contract");
(bool success, bytes memory returndata) = target.staticcall(data);
return _verifyCallResult(success, returndata, errorMessage);
}
/**
* @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
* but performing a delegate call.
*
* _Available since v3.4._
*/
function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
return functionDelegateCall(target, data, "Address: low-level delegate call failed");
}
/**
* @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
* but performing a delegate call.
*
* _Available since v3.4._
*/
function functionDelegateCall(
address target,
bytes memory data,
string memory errorMessage
) internal returns (bytes memory) {
require(isContract(target), "Address: delegate call to non-contract");
(bool success, bytes memory returndata) = target.delegatecall(data);
return _verifyCallResult(success, returndata, errorMessage);
}
function _verifyCallResult(
bool success,
bytes memory returndata,
string memory errorMessage
) private pure returns (bytes memory) {
if (success) {
return returndata;
} else {
// Look for revert reason and bubble it up if present
if (returndata.length > 0) {
// The easiest way to bubble the revert reason is using memory via assembly
assembly {
let returndata_size := mload(returndata)
revert(add(32, returndata), returndata_size)
}
} else {
revert(errorMessage);
}
}
}
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
/*
* @dev Provides information about the current execution context, including the
* sender of the transaction and its data. While these are generally available
* via msg.sender and msg.data, they should not be accessed in such a direct
* manner, since when dealing with meta-transactions the account sending and
* paying for execution may not be the actual sender (as far as an application
* is concerned).
*
* This contract is only required for intermediate, library-like contracts.
*/
abstract contract Context {
function _msgSender() internal view virtual returns (address) {
return msg.sender;
}
function _msgData() internal view virtual returns (bytes calldata) {
return msg.data;
}
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/cryptography/ECDSA.sol)
pragma solidity ^0.8.0;
import "./Strings.sol";
/**
* @dev Elliptic Curve Digital Signature Algorithm (ECDSA) operations.
*
* These functions can be used to verify that a message was signed by the holder
* of the private keys of a given address.
*/
library ECDSA {
enum RecoverError {
NoError,
InvalidSignature,
InvalidSignatureLength,
InvalidSignatureS,
InvalidSignatureV
}
function _throwError(RecoverError error) private pure {
if (error == RecoverError.NoError) {
return; // no error: do nothing
} else if (error == RecoverError.InvalidSignature) {
revert("ECDSA: invalid signature");
} else if (error == RecoverError.InvalidSignatureLength) {
revert("ECDSA: invalid signature length");
} else if (error == RecoverError.InvalidSignatureS) {
revert("ECDSA: invalid signature 's' value");
} else if (error == RecoverError.InvalidSignatureV) {
revert("ECDSA: invalid signature 'v' value");
}
}
/**
* @dev Returns the address that signed a hashed message (`hash`) with
* `signature` or error string. This address can then be used for verification purposes.
*
* The `ecrecover` EVM opcode allows for malleable (non-unique) signatures:
* this function rejects them by requiring the `s` value to be in the lower
* half order, and the `v` value to be either 27 or 28.
*
* IMPORTANT: `hash` _must_ be the result of a hash operation for the
* verification to be secure: it is possible to craft signatures that
* recover to arbitrary addresses for non-hashed data. A safe way to ensure
* this is by receiving a hash of the original message (which may otherwise
* be too long), and then calling {toEthSignedMessageHash} on it.
*
* Documentation for signature generation:
* - with https://web3js.readthedocs.io/en/v1.3.4/web3-eth-accounts.html#sign[Web3.js]
* - with https://docs.ethers.io/v5/api/signer/#Signer-signMessage[ethers]
*
* _Available since v4.3._
*/
function tryRecover(bytes32 hash, bytes memory signature) internal pure returns (address, RecoverError) {
// Check the signature length
// - case 65: r,s,v signature (standard)
// - case 64: r,vs signature (cf https://eips.ethereum.org/EIPS/eip-2098) _Available since v4.1._
if (signature.length == 65) {
bytes32 r;
bytes32 s;
uint8 v;
// ecrecover takes the signature parameters, and the only way to get them
// currently is to use assembly.
assembly {
r := mload(add(signature, 0x20))
s := mload(add(signature, 0x40))
v := byte(0, mload(add(signature, 0x60)))
}
return tryRecover(hash, v, r, s);
} else if (signature.length == 64) {
bytes32 r;
bytes32 vs;
// ecrecover takes the signature parameters, and the only way to get them
// currently is to use assembly.
assembly {
r := mload(add(signature, 0x20))
vs := mload(add(signature, 0x40))
}
return tryRecover(hash, r, vs);
} else {
return (address(0), RecoverError.InvalidSignatureLength);
}
}
/**
* @dev Returns the address that signed a hashed message (`hash`) with
* `signature`. This address can then be used for verification purposes.
*
* The `ecrecover` EVM opcode allows for malleable (non-unique) signatures:
* this function rejects them by requiring the `s` value to be in the lower
* half order, and the `v` value to be either 27 or 28.
*
* IMPORTANT: `hash` _must_ be the result of a hash operation for the
* verification to be secure: it is possible to craft signatures that
* recover to arbitrary addresses for non-hashed data. A safe way to ensure
* this is by receiving a hash of the original message (which may otherwise
* be too long), and then calling {toEthSignedMessageHash} on it.
*/
function recover(bytes32 hash, bytes memory signature) internal pure returns (address) {
(address recovered, RecoverError error) = tryRecover(hash, signature);
_throwError(error);
return recovered;
}
/**
* @dev Overload of {ECDSA-tryRecover} that receives the `r` and `vs` short-signature fields separately.
*
* See https://eips.ethereum.org/EIPS/eip-2098[EIP-2098 short signatures]
*
* _Available since v4.3._
*/
function tryRecover(
bytes32 hash,
bytes32 r,
bytes32 vs
) internal pure returns (address, RecoverError) {
bytes32 s = vs & bytes32(0x7fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff);
uint8 v = uint8((uint256(vs) >> 255) + 27);
return tryRecover(hash, v, r, s);
}
/**
* @dev Overload of {ECDSA-recover} that receives the `r and `vs` short-signature fields separately.
*
* _Available since v4.2._
*/
function recover(
bytes32 hash,
bytes32 r,
bytes32 vs
) internal pure returns (address) {
(address recovered, RecoverError error) = tryRecover(hash, r, vs);
_throwError(error);
return recovered;
}
/**
* @dev Overload of {ECDSA-tryRecover} that receives the `v`,
* `r` and `s` signature fields separately.
*
* _Available since v4.3._
*/
function tryRecover(
bytes32 hash,
uint8 v,
bytes32 r,
bytes32 s
) internal pure returns (address, RecoverError) {
// EIP-2 still allows signature malleability for ecrecover(). Remove this possibility and make the signature
// unique. Appendix F in the Ethereum Yellow paper (https://ethereum.github.io/yellowpaper/paper.pdf), defines
// the valid range for s in (301): 0 < s < secp256k1n ÷ 2 + 1, and for v in (302): v ∈ {27, 28}. Most
// signatures from current libraries generate a unique signature with an s-value in the lower half order.
//
// If your library generates malleable signatures, such as s-values in the upper range, calculate a new s-value
// with 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEBAAEDCE6AF48A03BBFD25E8CD0364141 - s1 and flip v from 27 to 28 or
// vice versa. If your library also generates signatures with 0/1 for v instead 27/28, add 27 to v to accept
// these malleable signatures as well.
if (uint256(s) > 0x7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF5D576E7357A4501DDFE92F46681B20A0) {
return (address(0), RecoverError.InvalidSignatureS);
}
if (v != 27 && v != 28) {
return (address(0), RecoverError.InvalidSignatureV);
}
// If the signature is valid (and not malleable), return the signer address
address signer = ecrecover(hash, v, r, s);
if (signer == address(0)) {
return (address(0), RecoverError.InvalidSignature);
}
return (signer, RecoverError.NoError);
}
/**
* @dev Overload of {ECDSA-recover} that receives the `v`,
* `r` and `s` signature fields separately.
*/
function recover(
bytes32 hash,
uint8 v,
bytes32 r,
bytes32 s
) internal pure returns (address) {
(address recovered, RecoverError error) = tryRecover(hash, v, r, s);
_throwError(error);
return recovered;
}
/**
* @dev Returns an Ethereum Signed Message, created from a `hash`. This
* produces hash corresponding to the one signed with the
* https://eth.wiki/json-rpc/API#eth_sign[`eth_sign`]
* JSON-RPC method as part of EIP-191.
*
* See {recover}.
*/
function toEthSignedMessageHash(bytes32 hash) internal pure returns (bytes32) {
// 32 is the length in bytes of hash,
// enforced by the type signature above
return keccak256(abi.encodePacked("\x19Ethereum Signed Message:\n32", hash));
}
/**
* @dev Returns an Ethereum Signed Message, created from `s`. This
* produces hash corresponding to the one signed with the
* https://eth.wiki/json-rpc/API#eth_sign[`eth_sign`]
* JSON-RPC method as part of EIP-191.
*
* See {recover}.
*/
function toEthSignedMessageHash(bytes memory s) internal pure returns (bytes32) {
return keccak256(abi.encodePacked("\x19Ethereum Signed Message:\n", Strings.toString(s.length), s));
}
/**
* @dev Returns an Ethereum Signed Typed Data, created from a
* `domainSeparator` and a `structHash`. This produces hash corresponding
* to the one signed with the
* https://eips.ethereum.org/EIPS/eip-712[`eth_signTypedData`]
* JSON-RPC method as part of EIP-712.
*
* See {recover}.
*/
function toTypedDataHash(bytes32 domainSeparator, bytes32 structHash) internal pure returns (bytes32) {
return keccak256(abi.encodePacked("\x19\x01", domainSeparator, structHash));
}
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/cryptography/draft-EIP712.sol)
pragma solidity ^0.8.0;
import "./ECDSA.sol";
/**
* @dev https://eips.ethereum.org/EIPS/eip-712[EIP 712] is a standard for hashing and signing of typed structured data.
*
* The encoding specified in the EIP is very generic, and such a generic implementation in Solidity is not feasible,
* thus this contract does not implement the encoding itself. Protocols need to implement the type-specific encoding
* they need in their contracts using a combination of `abi.encode` and `keccak256`.
*
* This contract implements the EIP 712 domain separator ({_domainSeparatorV4}) that is used as part of the encoding
* scheme, and the final step of the encoding to obtain the message digest that is then signed via ECDSA
* ({_hashTypedDataV4}).
*
* The implementation of the domain separator was designed to be as efficient as possible while still properly updating
* the chain id to protect against replay attacks on an eventual fork of the chain.
*
* NOTE: This contract implements the version of the encoding known as "v4", as implemented by the JSON RPC method
* https://docs.metamask.io/guide/signing-data.html[`eth_signTypedDataV4` in MetaMask].
*
* _Available since v3.4._
*/
abstract contract EIP712 {
/* solhint-disable var-name-mixedcase */
// Cache the domain separator as an immutable value, but also store the chain id that it corresponds to, in order to
// invalidate the cached domain separator if the chain id changes.
bytes32 private immutable _CACHED_DOMAIN_SEPARATOR;
uint256 private immutable _CACHED_CHAIN_ID;
address private immutable _CACHED_THIS;
bytes32 private immutable _HASHED_NAME;
bytes32 private immutable _HASHED_VERSION;
bytes32 private immutable _TYPE_HASH;
/* solhint-enable var-name-mixedcase */
/**
* @dev Initializes the domain separator and parameter caches.
*
* The meaning of `name` and `version` is specified in
* https://eips.ethereum.org/EIPS/eip-712#definition-of-domainseparator[EIP 712]:
*
* - `name`: the user readable name of the signing domain, i.e. the name of the DApp or the protocol.
* - `version`: the current major version of the signing domain.
*
* NOTE: These parameters cannot be changed except through a xref:learn::upgrading-smart-contracts.adoc[smart
* contract upgrade].
*/
constructor(string memory name, string memory version) {
bytes32 hashedName = keccak256(bytes(name));
bytes32 hashedVersion = keccak256(bytes(version));
bytes32 typeHash = keccak256(
"EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)"
);
_HASHED_NAME = hashedName;
_HASHED_VERSION = hashedVersion;
_CACHED_CHAIN_ID = block.chainid;
_CACHED_DOMAIN_SEPARATOR = _buildDomainSeparator(typeHash, hashedName, hashedVersion);
_CACHED_THIS = address(this);
_TYPE_HASH = typeHash;
}
/**
* @dev Returns the domain separator for the current chain.
*/
function _domainSeparatorV4() internal view returns (bytes32) {
if (address(this) == _CACHED_THIS && block.chainid == _CACHED_CHAIN_ID) {
return _CACHED_DOMAIN_SEPARATOR;
} else {
return _buildDomainSeparator(_TYPE_HASH, _HASHED_NAME, _HASHED_VERSION);
}
}
function _buildDomainSeparator(
bytes32 typeHash,
bytes32 nameHash,
bytes32 versionHash
) private view returns (bytes32) {
return keccak256(abi.encode(typeHash, nameHash, versionHash, block.chainid, address(this)));
}
/**
* @dev Given an already https://eips.ethereum.org/EIPS/eip-712#definition-of-hashstruct[hashed struct], this
* function returns the hash of the fully encoded EIP712 message for this domain.
*
* This hash can be used together with {ECDSA-recover} to obtain the signer of a message. For example:
*
* ```solidity
* bytes32 digest = _hashTypedDataV4(keccak256(abi.encode(
* keccak256("Mail(address to,string contents)"),
* mailTo,
* keccak256(bytes(mailContents))
* )));
* address signer = ECDSA.recover(digest, signature);
* ```
*/
function _hashTypedDataV4(bytes32 structHash) internal view virtual returns (bytes32) {
return ECDSA.toTypedDataHash(_domainSeparatorV4(), structHash);
}
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
import "./IERC1155.sol";
import "./IERC1155Receiver.sol";
import "./IERC1155MetadataURI.sol";
import "./Address.sol";
import "./Context.sol";
import "./ERC165.sol";
/**
* @dev Implementation of the basic standard multi-token.
* See https://eips.ethereum.org/EIPS/eip-1155
* Originally based on code by Enjin: https://github.com/enjin/erc-1155
*
* _Available since v3.1._
*/
contract ERC1155 is Context, ERC165, IERC1155, IERC1155MetadataURI {
using Address for address;
// Mapping from token ID to account balances
mapping(uint256 => mapping(address => uint256)) private _balances;
// Mapping from account to operator approvals
mapping(address => mapping(address => bool)) private _operatorApprovals;
// Used as the URI for all token types by relying on ID substitution, e.g. https://token-cdn-domain/{id}.json
string private _uri;
/**
* @dev See {_setURI}.
*/
constructor(string memory uri_) {
_setURI(uri_);
}
/**
* @dev See {IERC165-supportsInterface}.
*/
function supportsInterface(bytes4 interfaceId) public view virtual override(ERC165, IERC165) returns (bool) {
return
interfaceId == type(IERC1155).interfaceId ||
interfaceId == type(IERC1155MetadataURI).interfaceId ||
super.supportsInterface(interfaceId);
}
/**
* @dev See {IERC1155MetadataURI-uri}.
*
* This implementation returns the same URI for *all* token types. It relies
* on the token type ID substitution mechanism
* https://eips.ethereum.org/EIPS/eip-1155#metadata[defined in the EIP].
*
* Clients calling this function must replace the `\{id\}` substring with the
* actual token type ID.
*/
function uri(uint256) public view virtual override returns (string memory) {
return _uri;
}
/**
* @dev See {IERC1155-balanceOf}.
*
* Requirements:
*
* - `account` cannot be the zero address.
*/
function balanceOf(address account, uint256 id) public view virtual override returns (uint256) {
require(account != address(0), "ERC1155: balance query for the zero address");
return _balances[id][account];
}
/**
* @dev See {IERC1155-balanceOfBatch}.
*
* Requirements:
*
* - `accounts` and `ids` must have the same length.
*/
function balanceOfBatch(address[] memory accounts, uint256[] memory ids)
public
view
virtual
override
returns (uint256[] memory)
{
require(accounts.length == ids.length, "ERC1155: accounts and ids length mismatch");
uint256[] memory batchBalances = new uint256[](accounts.length);
for (uint256 i = 0; i < accounts.length; ++i) {
batchBalances[i] = balanceOf(accounts[i], ids[i]);
}
return batchBalances;
}
/**
* @dev See {IERC1155-setApprovalForAll}.
*/
function setApprovalForAll(address operator, bool approved) public virtual override {
require(_msgSender() != operator, "ERC1155: setting approval status for self");
_operatorApprovals[_msgSender()][operator] = approved;
emit ApprovalForAll(_msgSender(), operator, approved);
}
/**
* @dev See {IERC1155-isApprovedForAll}.
*/
function isApprovedForAll(address account, address operator) public view virtual override returns (bool) {
return _operatorApprovals[account][operator];
}
/**
* @dev See {IERC1155-safeTransferFrom}.
*/
function safeTransferFrom(
address from,
address to,
uint256 id,
uint256 amount,
bytes memory data
) public virtual override {
require(
from == _msgSender() || isApprovedForAll(from, _msgSender()),
"ERC1155: caller is not owner nor approved"
);
_safeTransferFrom(from, to, id, amount, data);
}
/**
* @dev See {IERC1155-safeBatchTransferFrom}.
*/
function safeBatchTransferFrom(
address from,
address to,
uint256[] memory ids,
uint256[] memory amounts,
bytes memory data
) public virtual override {
require(
from == _msgSender() || isApprovedForAll(from, _msgSender()),
"ERC1155: transfer caller is not owner nor approved"
);
_safeBatchTransferFrom(from, to, ids, amounts, data);
}
/**
* @dev Transfers `amount` tokens of token type `id` from `from` to `to`.
*
* Emits a {TransferSingle} event.
*
* Requirements:
*
* - `to` cannot be the zero address.
* - `from` must have a balance of tokens of type `id` of at least `amount`.
* - If `to` refers to a smart contract, it must implement {IERC1155Receiver-onERC1155Received} and return the
* acceptance magic value.
*/
function _safeTransferFrom(
address from,
address to,
uint256 id,
uint256 amount,
bytes memory data
) internal virtual {
require(to != address(0), "ERC1155: transfer to the zero address");
address operator = _msgSender();
_beforeTokenTransfer(operator, from, to, _asSingletonArray(id), _asSingletonArray(amount), data);
uint256 fromBalance = _balances[id][from];
require(fromBalance >= amount, "ERC1155: insufficient balance for transfer");
unchecked {
_balances[id][from] = fromBalance - amount;
}
_balances[id][to] += amount;
emit TransferSingle(operator, from, to, id, amount);
_doSafeTransferAcceptanceCheck(operator, from, to, id, amount, data);
}
/**
* @dev xref:ROOT:erc1155.adoc#batch-operations[Batched] version of {_safeTransferFrom}.
*
* Emits a {TransferBatch} event.
*
* Requirements:
*
* - If `to` refers to a smart contract, it must implement {IERC1155Receiver-onERC1155BatchReceived} and return the
* acceptance magic value.
*/
function _safeBatchTransferFrom(
address from,
address to,
uint256[] memory ids,
uint256[] memory amounts,
bytes memory data
) internal virtual {
require(ids.length == amounts.length, "ERC1155: ids and amounts length mismatch");
require(to != address(0), "ERC1155: transfer to the zero address");
address operator = _msgSender();
_beforeTokenTransfer(operator, from, to, ids, amounts, data);
for (uint256 i = 0; i < ids.length; ++i) {
uint256 id = ids[i];
uint256 amount = amounts[i];
uint256 fromBalance = _balances[id][from];
require(fromBalance >= amount, "ERC1155: insufficient balance for transfer");
unchecked {
_balances[id][from] = fromBalance - amount;
}
_balances[id][to] += amount;
}
emit TransferBatch(operator, from, to, ids, amounts);
_doSafeBatchTransferAcceptanceCheck(operator, from, to, ids, amounts, data);
}
/**
* @dev Sets a new URI for all token types, by relying on the token type ID
* substitution mechanism
* https://eips.ethereum.org/EIPS/eip-1155#metadata[defined in the EIP].
*
* By this mechanism, any occurrence of the `\{id\}` substring in either the
* URI or any of the amounts in the JSON file at said URI will be replaced by
* clients with the token type ID.
*
* For example, the `https://token-cdn-domain/\{id\}.json` URI would be
* interpreted by clients as
* `https://token-cdn-domain/000000000000000000000000000000000000000000000000000000000004cce0.json`
* for token type ID 0x4cce0.
*
* See {uri}.
*
* Because these URIs cannot be meaningfully represented by the {URI} event,
* this function emits no events.
*/
function _setURI(string memory newuri) internal virtual {
_uri = newuri;
}
/**
* @dev Creates `amount` tokens of token type `id`, and assigns them to `account`.
*
* Emits a {TransferSingle} event.
*
* Requirements:
*
* - `account` cannot be the zero address.
* - If `account` refers to a smart contract, it must implement {IERC1155Receiver-onERC1155Received} and return the
* acceptance magic value.
*/
function _mint(
address account,
uint256 id,
uint256 amount,
bytes memory data
) internal virtual {
require(account != address(0), "ERC1155: mint to the zero address");
address operator = _msgSender();
_beforeTokenTransfer(operator, address(0), account, _asSingletonArray(id), _asSingletonArray(amount), data);
_balances[id][account] += amount;
emit TransferSingle(operator, address(0), account, id, amount);
_doSafeTransferAcceptanceCheck(operator, address(0), account, id, amount, data);
}
/**
* @dev xref:ROOT:erc1155.adoc#batch-operations[Batched] version of {_mint}.
*
* Requirements:
*
* - `ids` and `amounts` must have the same length.
* - If `to` refers to a smart contract, it must implement {IERC1155Receiver-onERC1155BatchReceived} and return the
* acceptance magic value.
*/
function _mintBatch(
address to,
uint256[] memory ids,
uint256[] memory amounts,
bytes memory data
) internal virtual {
require(to != address(0), "ERC1155: mint to the zero address");
require(ids.length == amounts.length, "ERC1155: ids and amounts length mismatch");
address operator = _msgSender();
_beforeTokenTransfer(operator, address(0), to, ids, amounts, data);
for (uint256 i = 0; i < ids.length; i++) {
_balances[ids[i]][to] += amounts[i];
}
emit TransferBatch(operator, address(0), to, ids, amounts);
_doSafeBatchTransferAcceptanceCheck(operator, address(0), to, ids, amounts, data);
}
/**
* @dev Destroys `amount` tokens of token type `id` from `account`
*
* Requirements:
*
* - `account` cannot be the zero address.
* - `account` must have at least `amount` tokens of token type `id`.
*/
function _burn(
address account,
uint256 id,
uint256 amount
) internal virtual {
require(account != address(0), "ERC1155: burn from the zero address");
address operator = _msgSender();
_beforeTokenTransfer(operator, account, address(0), _asSingletonArray(id), _asSingletonArray(amount), "");
uint256 accountBalance = _balances[id][account];
require(accountBalance >= amount, "ERC1155: burn amount exceeds balance");
unchecked {
_balances[id][account] = accountBalance - amount;
}
emit TransferSingle(operator, account, address(0), id, amount);
}
/**
* @dev xref:ROOT:erc1155.adoc#batch-operations[Batched] version of {_burn}.
*
* Requirements:
*
* - `ids` and `amounts` must have the same length.
*/
function _burnBatch(
address account,
uint256[] memory ids,
uint256[] memory amounts
) internal virtual {
require(account != address(0), "ERC1155: burn from the zero address");
require(ids.length == amounts.length, "ERC1155: ids and amounts length mismatch");
address operator = _msgSender();
_beforeTokenTransfer(operator, account, address(0), ids, amounts, "");
for (uint256 i = 0; i < ids.length; i++) {
uint256 id = ids[i];
uint256 amount = amounts[i];
uint256 accountBalance = _balances[id][account];
require(accountBalance >= amount, "ERC1155: burn amount exceeds balance");
unchecked {
_balances[id][account] = accountBalance - amount;
}
}
emit TransferBatch(operator, account, address(0), ids, amounts);
}
/**
* @dev Hook that is called before any token transfer. This includes minting
* and burning, as well as batched variants.
*
* The same hook is called on both single and batched variants. For single
* transfers, the length of the `id` and `amount` arrays will be 1.
*
* Calling conditions (for each `id` and `amount` pair):
*
* - When `from` and `to` are both non-zero, `amount` of ``from``'s tokens
* of token type `id` will be transferred to `to`.
* - When `from` is zero, `amount` tokens of token type `id` will be minted
* for `to`.
* - when `to` is zero, `amount` of ``from``'s tokens of token type `id`
* will be burned.
* - `from` and `to` are never both zero.
* - `ids` and `amounts` have the same, non-zero length.
*
* To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
*/
function _beforeTokenTransfer(
address operator,
address from,
address to,
uint256[] memory ids,
uint256[] memory amounts,
bytes memory data
) internal virtual {}
function _doSafeTransferAcceptanceCheck(
address operator,
address from,
address to,
uint256 id,
uint256 amount,
bytes memory data
) private {
if (to.isContract()) {
try IERC1155Receiver(to).onERC1155Received(operator, from, id, amount, data) returns (bytes4 response) {
if (response != IERC1155Receiver(to).onERC1155Received.selector) {
revert("ERC1155: ERC1155Receiver rejected tokens");
}
} catch Error(string memory reason) {
revert(reason);
} catch {
revert("ERC1155: transfer to non ERC1155Receiver implementer");
}
}
}
function _doSafeBatchTransferAcceptanceCheck(
address operator,
address from,
address to,
uint256[] memory ids,
uint256[] memory amounts,
bytes memory data
) private {
if (to.isContract()) {
try IERC1155Receiver(to).onERC1155BatchReceived(operator, from, ids, amounts, data) returns (
bytes4 response
) {
if (response != IERC1155Receiver(to).onERC1155BatchReceived.selector) {
revert("ERC1155: ERC1155Receiver rejected tokens");
}
} catch Error(string memory reason) {
revert(reason);
} catch {
revert("ERC1155: transfer to non ERC1155Receiver implementer");
}
}
}
function _asSingletonArray(uint256 element) private pure returns (uint256[] memory) {
uint256[] memory array = new uint256[](1);
array[0] = element;
return array;
}
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
import "./IERC165.sol";
/**
* @dev Implementation of the {IERC165} interface.
*
* Contracts that want to implement ERC165 should inherit from this contract and override {supportsInterface} to check
* for the additional interface id that will be supported. For example:
*
* ```solidity
* function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
* return interfaceId == type(MyInterface).interfaceId || super.supportsInterface(interfaceId);
* }
* ```
*
* Alternatively, {ERC165Storage} provides an easier to use but more expensive implementation.
*/
abstract contract ERC165 is IERC165 {
/**
* @dev See {IERC165-supportsInterface}.
*/
function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
return interfaceId == type(IERC165).interfaceId;
}
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
import "./IERC165.sol";
/**
* @dev Required interface of an ERC1155 compliant contract, as defined in the
* https://eips.ethereum.org/EIPS/eip-1155[EIP].
*
* _Available since v3.1._
*/
interface IERC1155 is IERC165 {
/**
* @dev Emitted when `value` tokens of token type `id` are transferred from `from` to `to` by `operator`.
*/
event TransferSingle(address indexed operator, address indexed from, address indexed to, uint256 id, uint256 value);
/**
* @dev Equivalent to multiple {TransferSingle} events, where `operator`, `from` and `to` are the same for all
* transfers.
*/
event TransferBatch(
address indexed operator,
address indexed from,
address indexed to,
uint256[] ids,
uint256[] values
);
/**
* @dev Emitted when `account` grants or revokes permission to `operator` to transfer their tokens, according to
* `approved`.
*/
event ApprovalForAll(address indexed account, address indexed operator, bool approved);
/**
* @dev Emitted when the URI for token type `id` changes to `value`, if it is a non-programmatic URI.
*
* If an {URI} event was emitted for `id`, the standard
* https://eips.ethereum.org/EIPS/eip-1155#metadata-extensions[guarantees] that `value` will equal the value
* returned by {IERC1155MetadataURI-uri}.
*/
event URI(string value, uint256 indexed id);
/**
* @dev Returns the amount of tokens of token type `id` owned by `account`.
*
* Requirements:
*
* - `account` cannot be the zero address.
*/
function balanceOf(address account, uint256 id) external view returns (uint256);
/**
* @dev xref:ROOT:erc1155.adoc#batch-operations[Batched] version of {balanceOf}.
*
* Requirements:
*
* - `accounts` and `ids` must have the same length.
*/
function balanceOfBatch(address[] calldata accounts, uint256[] calldata ids)
external
view
returns (uint256[] memory);
/**
* @dev Grants or revokes permission to `operator` to transfer the caller's tokens, according to `approved`,
*
* Emits an {ApprovalForAll} event.
*
* Requirements:
*
* - `operator` cannot be the caller.
*/
function setApprovalForAll(address operator, bool approved) external;
/**
* @dev Returns true if `operator` is approved to transfer ``account``'s tokens.
*
* See {setApprovalForAll}.
*/
function isApprovedForAll(address account, address operator) external view returns (bool);
/**
* @dev Transfers `amount` tokens of token type `id` from `from` to `to`.
*
* Emits a {TransferSingle} event.
*
* Requirements:
*
* - `to` cannot be the zero address.
* - If the caller is not `from`, it must be have been approved to spend ``from``'s tokens via {setApprovalForAll}.
* - `from` must have a balance of tokens of type `id` of at least `amount`.
* - If `to` refers to a smart contract, it must implement {IERC1155Receiver-onERC1155Received} and return the
* acceptance magic value.
*/
function safeTransferFrom(
address from,
address to,
uint256 id,
uint256 amount,
bytes calldata data
) external;
/**
* @dev xref:ROOT:erc1155.adoc#batch-operations[Batched] version of {safeTransferFrom}.
*
* Emits a {TransferBatch} event.
*
* Requirements:
*
* - `ids` and `amounts` must have the same length.
* - If `to` refers to a smart contract, it must implement {IERC1155Receiver-onERC1155BatchReceived} and return the
* acceptance magic value.
*/
function safeBatchTransferFrom(
address from,
address to,
uint256[] calldata ids,
uint256[] calldata amounts,
bytes calldata data
) external;
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
import "./IERC1155.sol";
/**
* @dev Interface of the optional ERC1155MetadataExtension interface, as defined
* in the https://eips.ethereum.org/EIPS/eip-1155#metadata-extensions[EIP].
*
* _Available since v3.1._
*/
interface IERC1155MetadataURI is IERC1155 {
/**
* @dev Returns the URI for token type `id`.
*
* If the `\{id\}` substring is present in the URI, it must be replaced by
* clients with the actual token type ID.
*/
function uri(uint256 id) external view returns (string memory);
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
import "./IERC165.sol";
/**
* @dev _Available since v3.1._
*/
interface IERC1155Receiver is IERC165 {
/**
@dev Handles the receipt of a single ERC1155 token type. This function is
called at the end of a `safeTransferFrom` after the balance has been updated.
To accept the transfer, this must return
`bytes4(keccak256("onERC1155Received(address,address,uint256,uint256,bytes)"))`
(i.e. 0xf23a6e61, or its own function selector).
@param operator The address which initiated the transfer (i.e. msg.sender)
@param from The address which previously owned the token
@param id The ID of the token being transferred
@param value The amount of tokens being transferred
@param data Additional data with no specified format
@return `bytes4(keccak256("onERC1155Received(address,address,uint256,uint256,bytes)"))` if transfer is allowed
*/
function onERC1155Received(
address operator,
address from,
uint256 id,
uint256 value,
bytes calldata data
) external returns (bytes4);
/**
@dev Handles the receipt of a multiple ERC1155 token types. This function
is called at the end of a `safeBatchTransferFrom` after the balances have
been updated. To accept the transfer(s), this must return
`bytes4(keccak256("onERC1155BatchReceived(address,address,uint256[],uint256[],bytes)"))`
(i.e. 0xbc197c81, or its own function selector).
@param operator The address which initiated the batch transfer (i.e. msg.sender)
@param from The address which previously owned the token
@param ids An array containing ids of each token being transferred (order and length must match values array)
@param values An array containing amounts of each token being transferred (order and length must match ids array)
@param data Additional data with no specified format
@return `bytes4(keccak256("onERC1155BatchReceived(address,address,uint256[],uint256[],bytes)"))` if transfer is allowed
*/
function onERC1155BatchReceived(
address operator,
address from,
uint256[] calldata ids,
uint256[] calldata values,
bytes calldata data
) external returns (bytes4);
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
/**
* @dev Interface of the ERC165 standard, as defined in the
* https://eips.ethereum.org/EIPS/eip-165[EIP].
*
* Implementers can declare support of contract interfaces, which can then be
* queried by others ({ERC165Checker}).
*
* For an implementation, see {ERC165}.
*/
interface IERC165 {
/**
* @dev Returns true if this contract implements the interface defined by
* `interfaceId`. See the corresponding
* https://eips.ethereum.org/EIPS/eip-165#how-interfaces-are-identified[EIP section]
* to learn more about how these ids are created.
*
* This function call must use less than 30 000 gas.
*/
function supportsInterface(bytes4 interfaceId) external view returns (bool);
}
// SPDX-License-Identifier: MIT
pragma solidity 0.8.9;
import "./ERC1155.sol";
import "./IERC1155.sol";
import "./Ownable.sol";
import "./Strings.sol";
import "./ECDSA.sol";
import "./EIP712.sol";
contract MerchMintPass is ERC1155, EIP712, Ownable {
using Strings for string;
mapping(uint256 => uint256) private _totalSupply;
//signature
string private constant SINGING_DOMAIN = "MINTPASS";
string private constant SIGNATURE_VERSION = "1";
//constants
uint256 public burnedCounter;
uint256 public totalMinted;
uint256 public maxMintPerWallet = 1;
uint256 public maxMintPerWalletPuzzler = 1;
//mappings
mapping(uint256 => bool) private soldOut;
mapping(address => uint256) private mintCountMap;
mapping(address => uint256) private allowedMintCountMap;
mapping(address => uint256) private mintCountMapPuzzler;
mapping(address => uint256) private allowedMintCountMapPuzzler;
uint256 constant level1 = 1;
uint256 constant level2 = 2;
uint256 constant level3 = 3;
uint256 constant puzzler = 4;
event Redeemed(address indexed from, uint256 id, uint256 uuid);
string public _baseURI;
string public _contractURI;
bool saleLive = false;
bool burnLive = false;
constructor()
ERC1155(_baseURI)
EIP712(SINGING_DOMAIN, SIGNATURE_VERSION)
{}
function mintLevel1(uint256 qty, string memory name, bytes memory signature) public {
require(check(name, signature) == msg.sender, "Signature Invalid"); //server side signature
require(saleLive, "sale is not live");
require(soldOut[level1] == false, "item out of stock");
require(allowedMintCount(msg.sender) >= 1,"You minted too many");
totalMinted = totalMinted + qty;
_totalSupply[level1] = _totalSupply[level1] + qty;
_mint(msg.sender, level1, qty, "0x0000");
updateMintCount(msg.sender);
}
function mintLevel2(uint256 qty, string memory name, bytes memory signature) public {
require(check(name, signature) == msg.sender, "Signature Invalid"); //server side signature
require(saleLive, "sale is not live");
require(soldOut[level2] == false, "item out of stock");
require(allowedMintCount(msg.sender) >= 1,"You minted too many");
totalMinted = totalMinted + qty;
_totalSupply[level2] = _totalSupply[level2] + qty;
_mint(msg.sender, level1, qty, "0x0000");
_mint(msg.sender, level2, qty, "0x0000");
updateMintCount(msg.sender);
}
function mintLevel3(uint256 qty, string memory name, bytes memory signature) public {
require(check(name, signature) == msg.sender, "Signature Invalid"); //server side signature
require(saleLive, "sale is not live");
require(soldOut[level3] == false, "item out of stock");
require(allowedMintCount(msg.sender) >= 1,"You already minted");
totalMinted = totalMinted + qty;
_totalSupply[level3] = _totalSupply[level3] + qty;
_mint(msg.sender, level1, qty, "0x0000");
_mint(msg.sender, level2, qty, "0x0000");
_mint(msg.sender, level3, qty, "0x0000");
updateMintCount(msg.sender);
}
function mintPuzzler(uint256 qty, string memory name, bytes memory signature) public {
require(check(name, signature) == msg.sender, "Signature Invalid"); //server side signature
require(saleLive, "sale is not live");
require(soldOut[puzzler] == false, "item out of stock");
require(allowedMintCountPuzzler(msg.sender) >= 1,"You already minted");
totalMinted = totalMinted + qty;
_totalSupply[puzzler] = _totalSupply[puzzler] + qty;
_mint(msg.sender, puzzler, qty, "0x0000");
updateMintCountPuzzler(msg.sender);
}
//redeem function
function burn(
address account,
uint256 id,
uint256 qty,
uint256 uuid
) public virtual {
require(burnLive, "burn is not enabled");
require(
account == _msgSender() || isApprovedForAll(account, _msgSender()),
"ERC1155: caller is not owner nor approved"
);
require(balanceOf(account, id) >= qty, "balance too low");
burnedCounter = burnedCounter + qty;
_burn(account, id, qty);
emit Redeemed(account, id, uuid);
}
function check(string memory name, bytes memory signature) public view returns (address) {
return _verify( name, signature);
}
function _verify(string memory name, bytes memory signature) internal view returns (address) {
bytes32 digest = _hash(name);
return ECDSA.recover(digest, signature);
}
function _hash(string memory name) internal view returns (bytes32) {
return _hashTypedDataV4(keccak256(abi.encode(
keccak256("Web3Struct(string name)"),
keccak256(bytes(name))
)));
}
function setBaseURI(string memory newuri) public onlyOwner {
_baseURI = newuri;
}
function setContractURI(string memory newuri) public onlyOwner {
_contractURI = newuri;
}
function uri(uint256 tokenId) public view override returns (string memory) {
return string(abi.encodePacked(_baseURI, uint2str(tokenId)));
}
function contractURI() public view returns (string memory) {
return _contractURI;
}
function uint2str(uint256 _i) internal pure returns (string memory _uintAsString) {
if (_i == 0) {return "0";}
uint256 j = _i;
uint256 len;
while (j != 0) {len++; j /= 10;}
bytes memory bstr = new bytes(len);
uint256 k = len;
while (_i != 0) {
k = k - 1;
uint8 temp = (48 + uint8(_i - (_i / 10) * 10));
bytes1 b1 = bytes1(temp);
bstr[k] = b1;
_i /= 10;
}
return string(bstr);
}
function allowedMintCount(address minter) public view returns (uint256) {
return maxMintPerWallet - mintCountMap[minter];
}
function updateMintCount(address minter) private {
mintCountMap[minter] += 1;
}
function allowedMintCountPuzzler(address minter) public view returns (uint256) {
return maxMintPerWalletPuzzler - mintCountMapPuzzler[minter];
}
function updateMintCountPuzzler(address minter) private {
mintCountMapPuzzler[minter] += 1;
}
function totalSupply(uint256 id) public view virtual returns (uint256) {
return _totalSupply[id];
}
function exists(uint256 id) public view virtual returns (bool) {
return totalSupply(id) > 0;
}
// sets soldout
function setSoldOut(uint256 _id, bool isSoldOut) external onlyOwner {
soldOut[_id] = isSoldOut;
}
// enables sales
function setSaleLive(bool _saleLive) external onlyOwner {
saleLive = _saleLive;
}
//max switch
function setMaxPerWallet(uint256 _newMaxMintAmount) public onlyOwner {
maxMintPerWallet = _newMaxMintAmount;
}
function setMaxPerWalletPuzzler(uint256 _newMaxMintAmount) public onlyOwner {
maxMintPerWalletPuzzler = _newMaxMintAmount;
}
// enables burn
function setBurnLive(bool _burnLive) external onlyOwner {
burnLive = _burnLive;
}
function withdrawToOwner() external onlyOwner {
payable(msg.sender).transfer(address(this).balance);
}
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
import "./Context.sol";
/**
* @dev Contract module which provides a basic access control mechanism, where
* there is an account (an owner) that can be granted exclusive access to
* specific functions.
*
* By default, the owner account will be the one that deploys the contract. This
* can later be changed with {transferOwnership}.
*
* This module is used through inheritance. It will make available the modifier
* `onlyOwner`, which can be applied to your functions to restrict their use to
* the owner.
*/
abstract contract Ownable is Context {
address private _owner;
event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);
/**
* @dev Initializes the contract setting the deployer as the initial owner.
*/
constructor() {
_setOwner(_msgSender());
}
/**
* @dev Returns the address of the current owner.
*/
function owner() public view virtual returns (address) {
return _owner;
}
/**
* @dev Throws if called by any account other than the owner.
*/
modifier onlyOwner() {
require(owner() == _msgSender(), "Ownable: caller is not the owner");
_;
}
/**
* @dev Leaves the contract without owner. It will not be possible to call
* `onlyOwner` functions anymore. Can only be called by the current owner.
*
* NOTE: Renouncing ownership will leave the contract without an owner,
* thereby removing any functionality that is only available to the owner.
*/
function renounceOwnership() public virtual onlyOwner {
_setOwner(address(0));
}
/**
* @dev Transfers ownership of the contract to a new account (`newOwner`).
* Can only be called by the current owner.
*/
function transferOwnership(address newOwner) public virtual onlyOwner {
require(newOwner != address(0), "Ownable: new owner is the zero address");
_setOwner(newOwner);
}
function _setOwner(address newOwner) private {
address oldOwner = _owner;
_owner = newOwner;
emit OwnershipTransferred(oldOwner, newOwner);
}
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
/**
* @dev String operations.
*/
library Strings {
bytes16 private constant _HEX_SYMBOLS = "0123456789abcdef";
/**
* @dev Converts a `uint256` to its ASCII `string` decimal representation.
*/
function toString(uint256 value) internal pure returns (string memory) {
// Inspired by OraclizeAPI's implementation - MIT licence
// https://github.com/oraclize/ethereum-api/blob/b42146b063c7d6ee1358846c198246239e9360e8/oraclizeAPI_0.4.25.sol
if (value == 0) {
return "0";
}
uint256 temp = value;
uint256 digits;
while (temp != 0) {
digits++;
temp /= 10;
}
bytes memory buffer = new bytes(digits);
while (value != 0) {
digits -= 1;
buffer[digits] = bytes1(uint8(48 + uint256(value % 10)));
value /= 10;
}
return string(buffer);
}
/**
* @dev Converts a `uint256` to its ASCII `string` hexadecimal representation.
*/
function toHexString(uint256 value) internal pure returns (string memory) {
if (value == 0) {
return "0x00";
}
uint256 temp = value;
uint256 length = 0;
while (temp != 0) {
length++;
temp >>= 8;
}
return toHexString(value, length);
}
/**
* @dev Converts a `uint256` to its ASCII `string` hexadecimal representation with fixed length.
*/
function toHexString(uint256 value, uint256 length) internal pure returns (string memory) {
bytes memory buffer = new bytes(2 * length + 2);
buffer[0] = "0";
buffer[1] = "x";
for (uint256 i = 2 * length + 1; i > 1; --i) {
buffer[i] = _HEX_SYMBOLS[value & 0xf];
value >>= 4;
}
require(value == 0, "Strings: hex length insufficient");
return string(buffer);
}
}