Contract Source Code:
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.5.0) (utils/Address.sol)
pragma solidity ^0.8.1;
/**
* @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
* ====
*
* [IMPORTANT]
* ====
* You shouldn't rely on `isContract` to protect against flash loan attacks!
*
* Preventing calls from contracts is highly discouraged. It breaks composability, breaks support for smart wallets
* like Gnosis Safe, and does not provide security since it can be circumvented by calling from a contract
* constructor.
* ====
*/
function isContract(address account) internal view returns (bool) {
// This method relies on extcodesize/address.code.length, which returns 0
// for contracts in construction, since the code is only stored at the end
// of the constructor execution.
return account.code.length > 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);
}
/**
* @dev Tool to verifies that a low level call was successful, and revert if it wasn't, either by bubbling the
* revert reason using the provided one.
*
* _Available since v4.3._
*/
function verifyCallResult(
bool success,
bytes memory returndata,
string memory errorMessage
) internal 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
// OpenZeppelin Contracts v4.4.1 (utils/Context.sol)
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/Counters.sol)
pragma solidity ^0.8.0;
/**
* @title Counters
* @author Matt Condon (@shrugs)
* @dev Provides counters that can only be incremented, decremented or reset. This can be used e.g. to track the number
* of elements in a mapping, issuing ERC721 ids, or counting request ids.
*
* Include with `using Counters for Counters.Counter;`
*/
library Counters {
struct Counter {
// This variable should never be directly accessed by users of the library: interactions must be restricted to
// the library's function. As of Solidity v0.5.2, this cannot be enforced, though there is a proposal to add
// this feature: see https://github.com/ethereum/solidity/issues/4637
uint256 _value; // default: 0
}
function current(Counter storage counter) internal view returns (uint256) {
return counter._value;
}
function increment(Counter storage counter) internal {
unchecked {
counter._value += 1;
}
}
function decrement(Counter storage counter) internal {
uint256 value = counter._value;
require(value > 0, "Counter: decrement overflow");
unchecked {
counter._value = value - 1;
}
}
function reset(Counter storage counter) internal {
counter._value = 0;
}
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/introspection/ERC165.sol)
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
// OpenZeppelin Contracts (last updated v4.5.0) (token/ERC721/ERC721.sol)
pragma solidity ^0.8.0;
import "./IERC721.sol";
import "./IERC721Receiver.sol";
import "./IERC721Metadata.sol";
import "./Address.sol";
import "./Context.sol";
import "./Strings.sol";
import "./ERC165.sol";
/**
* @dev Implementation of https://eips.ethereum.org/EIPS/eip-721[ERC721] Non-Fungible Token Standard, including
* the Metadata extension, but not including the Enumerable extension, which is available separately as
* {ERC721Enumerable}.
*/
contract ERC721 is Context, ERC165, IERC721, IERC721Metadata {
using Address for address;
using Strings for uint256;
// Token name
string private _name;
// Token symbol
string private _symbol;
// Mapping from token ID to owner address
mapping(uint256 => address) private _owners;
// Mapping owner address to token count
mapping(address => uint256) private _balances;
// Mapping from token ID to approved address
mapping(uint256 => address) private _tokenApprovals;
// Mapping from owner to operator approvals
mapping(address => mapping(address => bool)) private _operatorApprovals;
/**
* @dev Initializes the contract by setting a `name` and a `symbol` to the token collection.
*/
constructor(string memory name_, string memory symbol_) {
_name = name_;
_symbol = symbol_;
}
/**
* @dev See {IERC165-supportsInterface}.
*/
function supportsInterface(bytes4 interfaceId) public view virtual override(ERC165, IERC165) returns (bool) {
return
interfaceId == type(IERC721).interfaceId ||
interfaceId == type(IERC721Metadata).interfaceId ||
super.supportsInterface(interfaceId);
}
/**
* @dev See {IERC721-balanceOf}.
*/
function balanceOf(address owner) public view virtual override returns (uint256) {
require(owner != address(0), "ERC721: balance query for the zero address");
return _balances[owner];
}
/**
* @dev See {IERC721-ownerOf}.
*/
function ownerOf(uint256 tokenId) public view virtual override returns (address) {
address owner = _owners[tokenId];
require(owner != address(0), "ERC721: owner query for nonexistent token");
return owner;
}
/**
* @dev See {IERC721Metadata-name}.
*/
function name() public view virtual override returns (string memory) {
return _name;
}
/**
* @dev See {IERC721Metadata-symbol}.
*/
function symbol() public view virtual override returns (string memory) {
return _symbol;
}
/**
* @dev See {IERC721Metadata-tokenURI}.
*/
function tokenURI(uint256 tokenId) public view virtual override returns (string memory) {
require(_exists(tokenId), "ERC721Metadata: URI query for nonexistent token");
string memory baseURI = _baseURI();
return bytes(baseURI).length > 0 ? string(abi.encodePacked(baseURI, tokenId.toString())) : "";
}
/**
* @dev Base URI for computing {tokenURI}. If set, the resulting URI for each
* token will be the concatenation of the `baseURI` and the `tokenId`. Empty
* by default, can be overriden in child contracts.
*/
function _baseURI() internal view virtual returns (string memory) {
return "";
}
/**
* @dev See {IERC721-approve}.
*/
function approve(address to, uint256 tokenId) public virtual override {
address owner = ERC721.ownerOf(tokenId);
require(to != owner, "ERC721: approval to current owner");
require(
_msgSender() == owner || isApprovedForAll(owner, _msgSender()),
"ERC721: approve caller is not owner nor approved for all"
);
_approve(to, tokenId);
}
/**
* @dev See {IERC721-getApproved}.
*/
function getApproved(uint256 tokenId) public view virtual override returns (address) {
require(_exists(tokenId), "ERC721: approved query for nonexistent token");
return _tokenApprovals[tokenId];
}
/**
* @dev See {IERC721-setApprovalForAll}.
*/
function setApprovalForAll(address operator, bool approved) public virtual override {
_setApprovalForAll(_msgSender(), operator, approved);
}
/**
* @dev See {IERC721-isApprovedForAll}.
*/
function isApprovedForAll(address owner, address operator) public view virtual override returns (bool) {
return _operatorApprovals[owner][operator];
}
/**
* @dev See {IERC721-transferFrom}.
*/
function transferFrom(
address from,
address to,
uint256 tokenId
) public virtual override {
//solhint-disable-next-line max-line-length
require(_isApprovedOrOwner(_msgSender(), tokenId), "ERC721: transfer caller is not owner nor approved");
_transfer(from, to, tokenId);
}
/**
* @dev See {IERC721-safeTransferFrom}.
*/
function safeTransferFrom(
address from,
address to,
uint256 tokenId
) public virtual override {
safeTransferFrom(from, to, tokenId, "");
}
/**
* @dev See {IERC721-safeTransferFrom}.
*/
function safeTransferFrom(
address from,
address to,
uint256 tokenId,
bytes memory _data
) public virtual override {
require(_isApprovedOrOwner(_msgSender(), tokenId), "ERC721: transfer caller is not owner nor approved");
_safeTransfer(from, to, tokenId, _data);
}
/**
* @dev Safely transfers `tokenId` token from `from` to `to`, checking first that contract recipients
* are aware of the ERC721 protocol to prevent tokens from being forever locked.
*
* `_data` is additional data, it has no specified format and it is sent in call to `to`.
*
* This internal function is equivalent to {safeTransferFrom}, and can be used to e.g.
* implement alternative mechanisms to perform token transfer, such as signature-based.
*
* Requirements:
*
* - `from` cannot be the zero address.
* - `to` cannot be the zero address.
* - `tokenId` token must exist and be owned by `from`.
* - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
*
* Emits a {Transfer} event.
*/
function _safeTransfer(
address from,
address to,
uint256 tokenId,
bytes memory _data
) internal virtual {
_transfer(from, to, tokenId);
require(_checkOnERC721Received(from, to, tokenId, _data), "ERC721: transfer to non ERC721Receiver implementer");
}
/**
* @dev Returns whether `tokenId` exists.
*
* Tokens can be managed by their owner or approved accounts via {approve} or {setApprovalForAll}.
*
* Tokens start existing when they are minted (`_mint`),
* and stop existing when they are burned (`_burn`).
*/
function _exists(uint256 tokenId) internal view virtual returns (bool) {
return _owners[tokenId] != address(0);
}
/**
* @dev Returns whether `spender` is allowed to manage `tokenId`.
*
* Requirements:
*
* - `tokenId` must exist.
*/
function _isApprovedOrOwner(address spender, uint256 tokenId) internal view virtual returns (bool) {
require(_exists(tokenId), "ERC721: operator query for nonexistent token");
address owner = ERC721.ownerOf(tokenId);
return (spender == owner || getApproved(tokenId) == spender || isApprovedForAll(owner, spender));
}
/**
* @dev Safely mints `tokenId` and transfers it to `to`.
*
* Requirements:
*
* - `tokenId` must not exist.
* - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
*
* Emits a {Transfer} event.
*/
function _safeMint(address to, uint256 tokenId) internal virtual {
_safeMint(to, tokenId, "");
}
/**
* @dev Same as {xref-ERC721-_safeMint-address-uint256-}[`_safeMint`], with an additional `data` parameter which is
* forwarded in {IERC721Receiver-onERC721Received} to contract recipients.
*/
function _safeMint(
address to,
uint256 tokenId,
bytes memory _data
) internal virtual {
_mint(to, tokenId);
require(
_checkOnERC721Received(address(0), to, tokenId, _data),
"ERC721: transfer to non ERC721Receiver implementer"
);
}
/**
* @dev Mints `tokenId` and transfers it to `to`.
*
* WARNING: Usage of this method is discouraged, use {_safeMint} whenever possible
*
* Requirements:
*
* - `tokenId` must not exist.
* - `to` cannot be the zero address.
*
* Emits a {Transfer} event.
*/
function _mint(address to, uint256 tokenId) internal virtual {
require(to != address(0), "ERC721: mint to the zero address");
require(!_exists(tokenId), "ERC721: token already minted");
_beforeTokenTransfer(address(0), to, tokenId);
_balances[to] += 1;
_owners[tokenId] = to;
emit Transfer(address(0), to, tokenId);
_afterTokenTransfer(address(0), to, tokenId);
}
/**
* @dev Destroys `tokenId`.
* The approval is cleared when the token is burned.
*
* Requirements:
*
* - `tokenId` must exist.
*
* Emits a {Transfer} event.
*/
function _burn(uint256 tokenId) internal virtual {
address owner = ERC721.ownerOf(tokenId);
_beforeTokenTransfer(owner, address(0), tokenId);
// Clear approvals
_approve(address(0), tokenId);
_balances[owner] -= 1;
delete _owners[tokenId];
emit Transfer(owner, address(0), tokenId);
_afterTokenTransfer(owner, address(0), tokenId);
}
/**
* @dev Transfers `tokenId` from `from` to `to`.
* As opposed to {transferFrom}, this imposes no restrictions on msg.sender.
*
* Requirements:
*
* - `to` cannot be the zero address.
* - `tokenId` token must be owned by `from`.
*
* Emits a {Transfer} event.
*/
function _transfer(
address from,
address to,
uint256 tokenId
) internal virtual {
require(ERC721.ownerOf(tokenId) == from, "ERC721: transfer from incorrect owner");
require(to != address(0), "ERC721: transfer to the zero address");
_beforeTokenTransfer(from, to, tokenId);
// Clear approvals from the previous owner
_approve(address(0), tokenId);
_balances[from] -= 1;
_balances[to] += 1;
_owners[tokenId] = to;
emit Transfer(from, to, tokenId);
_afterTokenTransfer(from, to, tokenId);
}
/**
* @dev Approve `to` to operate on `tokenId`
*
* Emits a {Approval} event.
*/
function _approve(address to, uint256 tokenId) internal virtual {
_tokenApprovals[tokenId] = to;
emit Approval(ERC721.ownerOf(tokenId), to, tokenId);
}
/**
* @dev Approve `operator` to operate on all of `owner` tokens
*
* Emits a {ApprovalForAll} event.
*/
function _setApprovalForAll(
address owner,
address operator,
bool approved
) internal virtual {
require(owner != operator, "ERC721: approve to caller");
_operatorApprovals[owner][operator] = approved;
emit ApprovalForAll(owner, operator, approved);
}
/**
* @dev Internal function to invoke {IERC721Receiver-onERC721Received} on a target address.
* The call is not executed if the target address is not a contract.
*
* @param from address representing the previous owner of the given token ID
* @param to target address that will receive the tokens
* @param tokenId uint256 ID of the token to be transferred
* @param _data bytes optional data to send along with the call
* @return bool whether the call correctly returned the expected magic value
*/
function _checkOnERC721Received(
address from,
address to,
uint256 tokenId,
bytes memory _data
) private returns (bool) {
if (to.isContract()) {
try IERC721Receiver(to).onERC721Received(_msgSender(), from, tokenId, _data) returns (bytes4 retval) {
return retval == IERC721Receiver.onERC721Received.selector;
} catch (bytes memory reason) {
if (reason.length == 0) {
revert("ERC721: transfer to non ERC721Receiver implementer");
} else {
assembly {
revert(add(32, reason), mload(reason))
}
}
}
} else {
return true;
}
}
/**
* @dev Hook that is called before any token transfer. This includes minting
* and burning.
*
* Calling conditions:
*
* - When `from` and `to` are both non-zero, ``from``'s `tokenId` will be
* transferred to `to`.
* - When `from` is zero, `tokenId` will be minted for `to`.
* - When `to` is zero, ``from``'s `tokenId` will be burned.
* - `from` and `to` are never both zero.
*
* To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
*/
function _beforeTokenTransfer(
address from,
address to,
uint256 tokenId
) internal virtual {}
/**
* @dev Hook that is called after any transfer of tokens. This includes
* minting and burning.
*
* Calling conditions:
*
* - when `from` and `to` are both non-zero.
* - `from` and `to` are never both zero.
*
* To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
*/
function _afterTokenTransfer(
address from,
address to,
uint256 tokenId
) internal virtual {}
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/introspection/IERC165.sol)
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 ^0.8.17;
// from: https://eips.ethereum.org/EIPS/eip-2981#simple-summary
import "./IERC165.sol";
///
/// @dev Interface for the NFT Royalty Standard
///
interface IERC2981 is IERC165 {
/// ERC165 bytes to add to interface array - set in parent contract
/// implementing this standard
///
/// bytes4(keccak256("royaltyInfo(uint256,uint256)")) == 0x2a55205a
/// bytes4 private constant _INTERFACE_ID_ERC2981 = 0x2a55205a;
/// _registerInterface(_INTERFACE_ID_ERC2981);
/// @notice Called with the sale price to determine how much royalty
// is owed and to whom.
/// @param _tokenId - the NFT asset queried for royalty information
/// @param _salePrice - the sale price of the NFT asset specified by _tokenId
/// @return receiver - address of who should be sent the royalty payment
/// @return royaltyAmount - the royalty payment amount for _salePrice
function royaltyInfo(
uint256 _tokenId,
uint256 _salePrice
) external view returns (
address receiver,
uint256 royaltyAmount
);
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.18;
// from: https://eips.ethereum.org/EIPS/eip-4906
import "./IERC165.sol";
import "./IERC721.sol";
// interface id for IERC4906: '0x49064906'
/// @title EIP-721 Metadata Update Extension
interface IERC4906 is IERC165, IERC721 {
/// @dev This event emits when the metadata of a token is changed.
/// So that the third-party platforms such as NFT market could
/// timely update the images and related attributes of the NFT.
event MetadataUpdate(uint256 _tokenId);
/// @dev This event emits when the metadata of a range of tokens is changed.
/// So that the third-party platforms such as NFT market could
/// timely update the images and related attributes of the NFTs.
event BatchMetadataUpdate(uint256 _fromTokenId, uint256 _toTokenId);
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (token/ERC721/IERC721.sol)
pragma solidity ^0.8.0;
import "./IERC165.sol";
/**
* @dev Required interface of an ERC721 compliant contract.
*/
interface IERC721 is IERC165 {
/**
* @dev Emitted when `tokenId` token is transferred from `from` to `to`.
*/
event Transfer(address indexed from, address indexed to, uint256 indexed tokenId);
/**
* @dev Emitted when `owner` enables `approved` to manage the `tokenId` token.
*/
event Approval(address indexed owner, address indexed approved, uint256 indexed tokenId);
/**
* @dev Emitted when `owner` enables or disables (`approved`) `operator` to manage all of its assets.
*/
event ApprovalForAll(address indexed owner, address indexed operator, bool approved);
/**
* @dev Returns the number of tokens in ``owner``'s account.
*/
function balanceOf(address owner) external view returns (uint256 balance);
/**
* @dev Returns the owner of the `tokenId` token.
*
* Requirements:
*
* - `tokenId` must exist.
*/
function ownerOf(uint256 tokenId) external view returns (address owner);
/**
* @dev Safely transfers `tokenId` token from `from` to `to`, checking first that contract recipients
* are aware of the ERC721 protocol to prevent tokens from being forever locked.
*
* Requirements:
*
* - `from` cannot be the zero address.
* - `to` cannot be the zero address.
* - `tokenId` token must exist and be owned by `from`.
* - If the caller is not `from`, it must be have been allowed to move this token by either {approve} or {setApprovalForAll}.
* - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
*
* Emits a {Transfer} event.
*/
function safeTransferFrom(
address from,
address to,
uint256 tokenId
) external;
/**
* @dev Transfers `tokenId` token from `from` to `to`.
*
* WARNING: Usage of this method is discouraged, use {safeTransferFrom} whenever possible.
*
* Requirements:
*
* - `from` cannot be the zero address.
* - `to` cannot be the zero address.
* - `tokenId` token must be owned by `from`.
* - If the caller is not `from`, it must be approved to move this token by either {approve} or {setApprovalForAll}.
*
* Emits a {Transfer} event.
*/
function transferFrom(
address from,
address to,
uint256 tokenId
) external;
/**
* @dev Gives permission to `to` to transfer `tokenId` token to another account.
* The approval is cleared when the token is transferred.
*
* Only a single account can be approved at a time, so approving the zero address clears previous approvals.
*
* Requirements:
*
* - The caller must own the token or be an approved operator.
* - `tokenId` must exist.
*
* Emits an {Approval} event.
*/
function approve(address to, uint256 tokenId) external;
/**
* @dev Returns the account approved for `tokenId` token.
*
* Requirements:
*
* - `tokenId` must exist.
*/
function getApproved(uint256 tokenId) external view returns (address operator);
/**
* @dev Approve or remove `operator` as an operator for the caller.
* Operators can call {transferFrom} or {safeTransferFrom} for any token owned by the caller.
*
* Requirements:
*
* - The `operator` cannot be the caller.
*
* Emits an {ApprovalForAll} event.
*/
function setApprovalForAll(address operator, bool _approved) external;
/**
* @dev Returns if the `operator` is allowed to manage all of the assets of `owner`.
*
* See {setApprovalForAll}
*/
function isApprovedForAll(address owner, address operator) external view returns (bool);
/**
* @dev Safely transfers `tokenId` token from `from` to `to`.
*
* Requirements:
*
* - `from` cannot be the zero address.
* - `to` cannot be the zero address.
* - `tokenId` token must exist and be owned by `from`.
* - If the caller is not `from`, it must be approved to move this token by either {approve} or {setApprovalForAll}.
* - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
*
* Emits a {Transfer} event.
*/
function safeTransferFrom(
address from,
address to,
uint256 tokenId,
bytes calldata data
) external;
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (token/ERC721/extensions/IERC721Metadata.sol)
pragma solidity ^0.8.0;
import "./IERC721.sol";
/**
* @title ERC-721 Non-Fungible Token Standard, optional metadata extension
* @dev See https://eips.ethereum.org/EIPS/eip-721
*/
interface IERC721Metadata is IERC721 {
/**
* @dev Returns the token collection name.
*/
function name() external view returns (string memory);
/**
* @dev Returns the token collection symbol.
*/
function symbol() external view returns (string memory);
/**
* @dev Returns the Uniform Resource Identifier (URI) for `tokenId` token.
*/
function tokenURI(uint256 tokenId) external view returns (string memory);
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (token/ERC721/IERC721Receiver.sol)
pragma solidity ^0.8.0;
/**
* @title ERC721 token receiver interface
* @dev Interface for any contract that wants to support safeTransfers
* from ERC721 asset contracts.
*/
interface IERC721Receiver {
/**
* @dev Whenever an {IERC721} `tokenId` token is transferred to this contract via {IERC721-safeTransferFrom}
* by `operator` from `from`, this function is called.
*
* It must return its Solidity selector to confirm the token transfer.
* If any other value is returned or the interface is not implemented by the recipient, the transfer will be reverted.
*
* The selector can be obtained in Solidity with `IERC721.onERC721Received.selector`.
*/
function onERC721Received(
address operator,
address from,
uint256 tokenId,
bytes calldata data
) external returns (bytes4);
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (access/Ownable.sol)
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() {
_transferOwnership(_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 {
_transferOwnership(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");
_transferOwnership(newOwner);
}
/**
* @dev Transfers ownership of the contract to a new account (`newOwner`).
* Internal function without access restriction.
*/
function _transferOwnership(address newOwner) internal virtual {
address oldOwner = _owner;
_owner = newOwner;
emit OwnershipTransferred(oldOwner, newOwner);
}
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.26;
/// @title QRyou: a collection of on-chain writable qrcodes
/// @author germyjohn
import "./ERC721.sol";
import "./Counters.sol";
import "./Ownable.sol";
import "./IERC2981.sol";
import "./IERC4906.sol";
interface IstorageTools{
function read(address) external view returns (bytes memory);
function bytesToUint16Array(bytes memory) external pure returns(uint16[] memory);
function b64encode(bytes memory) external pure returns(string memory);
}
interface IgifBuilder{
function getImageBlock(uint8[] memory) external view returns(bytes memory);
}
interface IcensoredText{
function getCensoredText(bytes10) external view returns(string memory);
}
contract QRyou is ERC721, IERC2981, IERC4906, Ownable {
using Counters for Counters.Counter;
struct Token {
bytes10 salt;
bool locked;
address writer;
uint8 writeCount;
bytes message;
}
address internal constant censoredTextAddress = 0x2aDF11840B50e4019b81F8AbC5F7de7E86A4337E;
address internal constant toolsAddress = 0x744F25b06DEbc03a909c8CED93Fa121C6c47B773;
address internal constant positionsAddress = 0x88462a7c26b8F9f88C7f8472E2bB1B76775964E0;
address internal constant stencilAddress = 0xB3956Fa40418c5282f0D15881Ac374f6a7c371Fa;
address internal constant gifLzwAddress = 0x4563C42456CA63f68e0dE8bc84dc7988F9D6950D;
mapping(uint256 => Token) internal tokens;
/// @notice the number of mints by given address
mapping(address => uint256) public mintsBy;
Counters.Counter private supply;
/// @notice the value to be sent for each mint
uint256 public mintFee = 0.0069 ether;
/// @notice the number of mints allowed per address
uint256 public constant maxMints = 10;
/// @notice the max supply for this collection. may changed to a lower value by calling lockMint.
uint256 public maxSupply = 4200;
/// @notice minting state. toggled by toggleMint.
bool public mintEnabled = false;
uint256 royaltyPercent = 2;
string public externalURL = "https://nometa.online/qryou";
string public constant description = "Writable qrcodes fully on-chained";
string internal constant nameStart = "QRyou #";
constructor() payable ERC721('QRyou','QRU') {}
/* interface id for IERC2981: '0x2a55205a' */
/* interface id for IERC4906: '0x49064906' */
function supportsInterface(bytes4 interfaceId)
public view override(IERC165, ERC721) returns (bool) {
return
interfaceId == type(IERC721).interfaceId ||
interfaceId == type(IERC721Metadata).interfaceId ||
interfaceId == type(IERC2981).interfaceId ||
interfaceId == bytes4(0x49064906) ||
super.supportsInterface(interfaceId);
}
receive() external payable {}
// token logic ===================================================
modifier tokenExists(uint256 _tokenId) {
require(_exists(_tokenId), "token does not exist");
_;
}
/// @notice returns the number of tokens in the collection
function totalSupply() external view returns (uint256) {
return supply.current();
}
/// @notice Mint given number of tokens
/// @param _mints The number of tokens to mint. Max 10.
function mint(uint256 _mints) external payable {
address msgSender = msg.sender;
uint256 mints = _mints;
unchecked {
require((supply.current() + mints) <= maxSupply, "exceeds max supply");
if (msgSender != owner()) {
require(msg.value == mints * mintFee, "invald value for tranasction");
require(mintEnabled, "minting is disabled");
}
require((mintsBy[msgSender] + mints) <= maxMints, "mint limit of 10");
mintsBy[msgSender] += mints;
for (uint256 count = 1; count <= mints; count++) {
supply.increment();
uint256 tokenId = supply.current();
tokens[tokenId].salt = bytes10(keccak256(abi.encodePacked(
tokenId,
block.prevrandao
)));
_safeMint(msgSender, tokenId);
}
}
}
/// @notice encode a message into a qrcode. a holder can write to any unlocked token
/// @param _tokenId the token id to write to
/// @param _message the message to encode. max 78 characters.
function writeMessage(uint256 _tokenId, string memory _message) external tokenExists(_tokenId) {
uint256 tokenId = _tokenId;
bytes memory messageBytes = bytes(_message);
Token storage thisToken = tokens[tokenId];
address writer = msg.sender;
address tokenOwner = ownerOf(tokenId);
require(messageBytes.length <= 78, "message too long");
if (thisToken.locked) {
require(writer == tokenOwner, "only owner can write");
} else {
require(balanceOf(writer) > 0, "only holders can write");
}
thisToken.writer = (writer == tokenOwner) ? address(0) : writer;
unchecked { thisToken.writeCount += 1; }
thisToken.message = messageBytes;
emit MetadataUpdate(tokenId);
}
/// @notice lock a token from being written by other token holders. this can not be undone.
function lockPublicWrite(uint256 _tokenId) external tokenExists(_tokenId) {
uint256 tokenId = _tokenId;
Token storage thisToken = tokens[tokenId];
require(msg.sender == ownerOf(tokenId), "not the owner");
require(! thisToken.locked, "token is locked");
thisToken.locked = true;
emit MetadataUpdate(tokenId);
}
/// @notice builds attributes to include in meatdata
function getAttributes(uint256 _tokenId) internal view returns (string memory) {
Token memory thisToken = tokens[_tokenId];
string memory attributes = '","attributes":[{"trait_type":"state","value":';
string memory lockedStr = thisToken.locked ? '"locked"}' : '"unlocked"}';
attributes = string.concat(
attributes,
lockedStr
);
if (thisToken.writeCount > 0) {
attributes = string.concat(
attributes,
',{"trait_type":"writeCount","value":',
Strings.toString(thisToken.writeCount),
'}'
);
}
if (thisToken.writer != address(0)) {
attributes = string.concat(
attributes,
',{"trait_type":"messageFrom","value":"',
string(getbyteStringAddress(thisToken.writer)),
'"}'
);
}
return string.concat(attributes, "]" );
}
/// @notice returns metadata for the token
function tokenURI(uint256 _tokenId)
public view virtual override tokenExists(_tokenId) returns (string memory) {
uint256 tokenId = _tokenId;
IstorageTools tools = IstorageTools(toolsAddress);
return string.concat(
'data:application/json;base64,',
tools.b64encode(bytes(string.concat(
'{"name":"',
getName(tokenId),
/* nameStart, */
/* ' #', */
/* Strings.toString(tokenId), */
'","description":"',
description,
'","external_url":"',
externalURL,
getAttributes(tokenId),
',"image":"',
packSvg(tokenId),
'"}'
)))
);
}
function packSvg(uint256 _tokenId) internal view returns(string memory) {
IstorageTools tools = IstorageTools(toolsAddress);
Token memory thisToken = tokens[_tokenId];
string memory colour;
if (thisToken.locked) {
colour = 'c32';
} else if (thisToken.writeCount == 0) {
colour = 'fff';
} else if (thisToken.writer == address(0)) {
colour = '000';
} else {
string[5] memory colours = ['e82', 'ed2', '0a1', '08d', '85b'];
colour = colours[(tokens[_tokenId].writeCount - 1) % 5];
}
return string.concat(
"data:image/svg+xml;base64,",
tools.b64encode(bytes(string.concat(
'<svg id="q" width="740" height="740" xmlns="http://www.w3.org/2000/svg">',
'<style>img{width:100%;height:100%;',
'image-rendering:pixelated;border-radius:14px;}</style>',
'<rect rx="40" width="740" height="740" fill="#000"></rect>',
'<rect rx="28" x="15" y="15" width="710" height="710" stroke="#',
colour,
'" stroke-width="10"></rect>',
'<foreignObject width="656" height="656" x="42" y="42">',
'<img xmlns="http://www.w3.org/1999/xhtml" src="data:image/gif;base64,',
tools.b64encode(packGif(_tokenId)),
'"/></foreignObject>',
'<animate attributeName="opacity" dur="2.2s" from="1" to="0.999" ',
'repeatCount="indefinite"/>',
'<script type="text/javascript"><![CDATA[',
'let q=document.getElementById("q");',
'q.style=`margin:${(q.parent == undefined)?"',
'calc((100vh - 740px)/2)":"0"} auto;background-color:#2e2e2e;`;]]>',
'</script></svg>'
)))
);
}
function genImageBlock(uint256 _tokenId) internal view returns(bytes memory) {
uint256 tokenId = _tokenId;
bytes memory message = tokens[tokenId].message;
/* if no message written */
if (message.length == 0) {
message = bytes(IcensoredText(censoredTextAddress).getCensoredText(tokens[tokenId].salt));
}
if (message.length == 0) {
message = bytes.concat(
bytes(getName(tokenId)),
' ',
bytes(getbyteStringAddress(ownerOf(tokenId)))
);
}
uint8[] memory imageArray = getImageArray(addEcc(encodeMessage(message)));
return IgifBuilder(gifLzwAddress).getImageBlock(imageArray);
}
// public only for testing
function packGif(uint256 _tokenId) public view returns(bytes memory) {
(bytes memory light, bytes memory dark, uint8[] memory glitches) = parseSalt(_tokenId);
bytes memory imageBlock = genImageBlock(_tokenId);
bytes1 bigTime = bytes1((glitches[0] % 3) + 1);
return bytes.concat(
hex'47494638396129002900f00000',
light,
dark,
// aeb: repeat indefinitely
hex'21FF0B4E45545343415045322E300301000000',
// gce: 3 sec (2c01), disposal (packed 04)
// 5 sec => f401
/* hex'21F90404f4010000', */
hex'21F90404',
bytes1(glitches[0] << 4),
bigTime,
hex'0000',
/* hex'010000', */
// id + code size
hex'2C00000000290029000002',
imageBlock,
hex'00',
// long invert 1st
// gce: 0.4 sec (2800), disposal (packed 04)
/* hex'21F9040428000000', */
hex'21F90404',
bytes1((glitches[1] % 50) + 10),
hex'000000',
// id: last byte flags local colour table (80)
hex'2C000000002900290080',
dark,
light,
hex'02', // mincode
imageBlock,
hex'00',
// gce: 0.1 sec (0a00), disposal (packed 04)
hex'21F904040a000000',
// id
hex'2C00000000290029000002',
this.glitch(imageBlock, glitches[2]),
hex'00',
// gce: 0.1 sec (0a00), disposal (packed 04)
hex'21F904040a000000',
// id
hex'2C00000000290029000002',
this.glitch(imageBlock, glitches[3]),
hex'003b'
);
}
/// @notice this function is external only for the sake of slicing bytes
function glitch(bytes calldata _imageBlock, uint8 _glitch) external pure returns(bytes memory) {
uint8 position = (_glitch % 60) + 10;
return bytes.concat(
_imageBlock[:position],
// might try ^ 85
bytes1(_glitch & 85),
/* bytes1(hex'55'), */
_imageBlock[position+1:]
);
}
/// @notice parse stored salt as light, dark colours and values for glitches
function parseSalt(uint256 _tokenId) internal view
returns(bytes memory, bytes memory, uint8[] memory) {
bytes10 salt = tokens[_tokenId].salt;
uint8[] memory glitches = new uint8[](4);
bytes memory light = '';
bytes memory dark = '';
uint16 contrast;
//gen light
uint8 count = 0;
// saves 2514 gas
unchecked {
for (uint256 i=0; i<3; i++) {
uint8 value = 255 - (uint8(salt[i]) % 90);
uint8 rgb;
if (value > 240) {rgb = 255;}
else if (value < 200 && count < 2) {
rgb = count == 0 || i == 2 ? 80:160;
count++;
}
else rgb = value;
contrast += rgb;
light = bytes.concat(light, bytes1(rgb));
}
// gen dark
// determine black or colour from adding rgb
count = 0;
for (uint256 i=0; i<3; i++) {
uint8 value = 0 + (uint8(salt[i+3]) % 70);
uint8 rgb;
if (contrast < 620) {rgb = 0;}
else if (value > 40 && count < 2) {
rgb = count == 0 || i == 0 ? 140 : 70;
count++;
}
else rgb = value;
dark = bytes.concat(dark, bytes1(rgb));
}
for (uint256 i=0; i<4; i++) {
glitches[i] = uint8(salt[i+6]);
}
}
return (light, dark, glitches);
}
/// @notice prepares the message with the qrcode mode and appropriate padding
function encodeMessage(bytes memory message) internal pure returns (uint8[] memory) {
uint8[] memory md = new uint8[](80);
uint8 length = uint8(message.length);
// saves 23574 gas
unchecked {
md[0] = uint8((0x04 << 4) + (length >> 4));
md[1] = uint8((length << 4) + uint8(message[0] >> 4));
for (uint8 i=0; i<length-1; i++) {
md[i+2] = uint8(message[i] << 4) + uint8(message[i+1] >> 4);
}
md[length+1] = uint8((message[length-1] << 4));
uint8[2] memory pad = [236,17];
// need to start with pad[0]
uint8 padShift = (length+2) % 2;
for (uint8 i=length+2; i<80; i++) {
md[i] = pad[(i + padShift) % 2];
}
}
return md;
}
/// @notice generates the error correction codes
function addEcc(uint8[] memory _message) internal pure returns(uint8[] memory) {
uint256 genLen = 21;
uint256 msgLen = 80;
uint8[] memory mc = new uint8[](msgLen + genLen);
uint8[21] memory ga = [0,17,60,79,50,61,163,26,187,202,180,221,225,83,239,156,164,212,212,188,190];
// create tables
uint8[] memory exp = new uint8[](256);
uint256[] memory log = new uint256[](256);
// saves 709906 gas
unchecked {
// moved next line from above
for (uint256 i ; i<msgLen; i++) { mc[i] = _message[i]; }
for (uint8 i=0; i<8; i++) { exp[i] = uint8(1) << i; }
for (uint256 i=8; i<256; i++) { exp[i] = (((exp[i - 4] ^ exp[i - 5]) ^ exp[i - 6]) ^ exp[i - 8]); }
for (uint256 i=0; i<255; i++) { log[exp[i]] = i; }
for (uint8 i=0; i<msgLen; i++) {
uint8[] memory q = new uint8[](21);
for (uint8 j; j<genLen; j++) {
if (mc[i] == 0) break;
q[j] = exp[(log[mc[i]] + ga[j]) % 255];
}
for (uint8 j=1; j<genLen; j++) {
mc[i+j] ^= q[j];
}
// rewrite the original _message code to first position
mc[i] = _message[i];
}
}
return mc;
}
//======================================================
function getImageArray(uint8[] memory _data) internal view returns(uint8[] memory) {
IstorageTools tools = IstorageTools(toolsAddress);
uint16[] memory positions = tools.bytesToUint16Array(tools.read(positionsAddress));
uint8[] memory imageArray = new uint8[](1681);
uint16[] memory stencil = tools.bytesToUint16Array(tools.read(stencilAddress));
uint256 stencilLength = stencil.length; //153
uint16 count = 807;
// unpack data bits and add to imageArray using positions
uint8 bit;
// saves 306566 gas
unchecked {
for (uint256 i=0; i<count; i++) {
bit = (_data[i/8] >> (7-(i % 8))) % 2;
// applying mask before placing
if (positions[i] % 2 == 0) { bit ^= 1; }
imageArray[positions[i]] = bit;
}
// apply stencil
for (uint256 i=0; i<stencilLength; i++) {
imageArray[stencil[i]] = 1;
}
}
return imageArray;
}
// utilities
function getName(uint256 _tokenId) internal pure returns(string memory) {
return string.concat(
nameStart,
Strings.toString(_tokenId)
);
}
/// @notice converts an address to a hexadecimal string with leading 0x
/// @param _address the address to convert
/// @return address as a string
function getbyteStringAddress(address _address) internal pure returns(bytes memory) {
bytes memory addressBytes = abi.encodePacked(_address);
bytes memory addressStringBytes = '0x';
bytes memory alphabet = "0123456789abcdef";
for (uint256 i=0; i<20; i++) {
addressStringBytes = bytes.concat(
addressStringBytes,
alphabet[uint8(addressBytes[i] >> 4)],
alphabet[uint8(addressBytes[i] & 0x0f)]
);
}
return addressStringBytes ;
}
/// @notice called with the sale price to determine how much royalty is owed and to whom.
/// @param _tokenId the NFT asset queried for royalty information
/// @param _salePrice the sale price of the NFT asset specified by _tokenId
/// @return receiver address of who should be sent the royalty payment
/// @return royaltyAmount the royalty payment amount for _salePrice
function royaltyInfo(uint256 _tokenId, uint256 _salePrice)
external view tokenExists(_tokenId)
returns(address receiver, uint256 royaltyAmount) {
return (owner(), _salePrice * royaltyPercent / 100);
}
/* owner control */
/// @notice Set the external address for metadata. onlyOwner
/// @param _url The new external url.
function setExternalURL(string calldata _url) external onlyOwner {
externalURL = _url;
}
/// @notice Toggles bool mintEnabled
function toggleMint() external onlyOwner {
require(supply.current() < maxSupply, "minting has ended");
mintEnabled = !mintEnabled;
}
/// @notice will permanently disable minting. This cannot be undone.
function lockMint() external onlyOwner {
maxSupply = supply.current();
mintEnabled = false;
}
function withdraw() external onlyOwner {
(bool success, ) = payable(owner()).call{value: address(this).balance}("");
require(success, "failed to withdraw");
}
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/Strings.sol)
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);
}
}