Contract Name:
PairedWorldRDF
Contract Source Code:
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.17;
import "@semanticSBT/contracts/interfaces/ISemanticSBT.sol";
import "@openzeppelin/contracts/access/Ownable.sol";
import "@openzeppelin/contracts/utils/Strings.sol";
import "@openzeppelin/contracts/security/ReentrancyGuard.sol";
interface SPOProxyInterface {
function addSPO(uint256 tokenId, uint8 predicateIdx, uint8 objectIdx, string memory object) external;
function removeRDF(uint256 tokenId, uint8 predicateIdx, uint8 objectIdx) external;
function getObject(uint256 tokenId, uint8 predicateIdx, uint8 objectIdx) external view returns (string memory);
}
contract PairedWorldRDF is Ownable, ISemanticSBT, ReentrancyGuard {
address public _sbt;
address public _admin;
SPOProxyInterface public _spoProxy;
string public _schemaUri;
string constant TURTLE_LINE_SUFFIX = " ;\n ";
string constant TURTLE_END_SUFFIX = " .";
string constant public ENTITY_PREFIX = ":";
string constant public PROPERTY_PREFIX = "p:";
string constant public SOUL_PREFIX = "SOUL_";
string constant CONCATENATION_CHARACTER = "_";
string constant BLANK_SPACE = " ";
mapping (uint8 => string) public _predicates;
mapping (string => uint8) public _predicatesToIdx;
mapping (uint8 => string) public _objectClasses;
mapping (string => uint8) public _objectClassesToIdx;
// Predicates have a 1-to-1 mapping to both subjectClasses and objectClasses
mapping (uint8 => uint8) public _POPairs;
// _maxPredicate[tokenID] = highest filled predicate for tokenID
mapping (uint256 => uint8) public _maxPredicate;
constructor(address sbt, address spoProxy, string memory schemaUri) {
_sbt = sbt;
_schemaUri = schemaUri;
_spoProxy = SPOProxyInterface(spoProxy);
_predicates[1] = "ownedBy";
_predicatesToIdx["ownedBy"] = 1;
_objectClasses[1] = "address";
_objectClassesToIdx["address"] = 1;
_POPairs[1] = 1;
}
modifier onlyAdmin() {
require(msg.sender == _admin || msg.sender == owner(), "Only Admin");
_;
}
modifier onlySbt() {
require(msg.sender == _sbt, "Only callable by the SBT contract");
_;
}
// MARK: - Only Owner
function setAdmin(address admin) external onlyOwner {
_admin = admin;
}
function setSbt(address sbt) external onlyOwner {
_sbt = sbt;
}
function setSPOProxy(address spoProxy) external onlyOwner {
_spoProxy = SPOProxyInterface(spoProxy);
}
// MARK: - Only Admin
function setSchemaUri(string memory schemaUri) external onlyAdmin {
_schemaUri = schemaUri;
}
function setPOPair(
uint8 predicateIdx,
string memory predicate,
uint8 objectClassIdx,
string memory objectClass
) external onlyAdmin {
require(_isStringEmpty(_predicates[predicateIdx]), "Predicate already exists in the same index");
require(_isStringEmpty(_objectClasses[objectClassIdx]), "Object class already exists in the same index");
require(!(objectClassIdx == 0 || predicateIdx == 0), "Cannot set reserved index");
require(_predicatesToIdx[predicate] == 0, "Predicate already exists");
require(_objectClassesToIdx[objectClass] == 0, "Object class already exists");
_predicates[predicateIdx] = predicate;
_predicatesToIdx[predicate] = predicateIdx;
_objectClasses[objectClassIdx] = objectClass;
_objectClassesToIdx[objectClass] = objectClassIdx;
_POPairs[predicateIdx] = objectClassIdx;
}
function updatePOPair(
uint8 predicateIdx,
string memory predicate,
uint8 objectClassIdx,
string memory objectClass
) external onlyAdmin {
require(!_isStringEmpty(_predicates[predicateIdx]), "Predicate doesn't exist. Use setPOPair instead");
require(!_isStringEmpty(_objectClasses[objectClassIdx]), "Object class doesn't exist. User setPOPair instead");
require(_POPairs[predicateIdx] == objectClassIdx, "Attempting to beak 1-to-1 PO relationship");
require(_predicatesToIdx[predicate] == 0 || _predicatesToIdx[predicate] == predicateIdx, "Predicate already exists");
require(_objectClassesToIdx[objectClass] == 0 || _objectClassesToIdx[objectClass] == objectClassIdx, "Object class already exists");
_predicates[predicateIdx] = predicate;
_predicatesToIdx[predicate] = predicateIdx;
_objectClasses[objectClassIdx] = objectClass;
_objectClassesToIdx[objectClass] = objectClassIdx;
}
// MARK: - onlySbt
function addSPO(
uint256 tokenId,
uint8 predicateIdx,
uint8 objectIdx,
string memory object
) external nonReentrant onlySbt {
require(!_isStringEmpty(_predicates[predicateIdx]), "Predicate doesn't exist");
require(!_isStringEmpty(_objectClasses[objectIdx]), "Object doesn't exist");
require(_POPairs[predicateIdx] == objectIdx, "Invalid SPO, predicate and object don't match");
bool creation = _maxPredicate[tokenId] == 0;
if (!creation) {
require(predicateIdx != 1, "cannot change owner SPO");
}
_spoProxy.addSPO(tokenId, predicateIdx, objectIdx, object);
if (_isStringEmpty(object)) {
_maxPredicate[tokenId] = _maxPredicate[tokenId] == predicateIdx ? predicateIdx - 1 : _maxPredicate[tokenId];
} else {
_maxPredicate[tokenId] = _maxPredicate[tokenId] < predicateIdx ? predicateIdx : _maxPredicate[tokenId];
}
if (creation) {
emit CreateRDF(tokenId, _buildRdfString(tokenId));
} else {
emit UpdateRDF(tokenId, _buildRdfString(tokenId));
}
}
function removeRDF(uint256 tokenId) external nonReentrant onlySbt {
require(_maxPredicate[tokenId] > 0, "No RDF to remove");
string memory oldData = _buildRdfString(tokenId);
for (uint8 i = 1; i <= _maxPredicate[tokenId]; i++) {
_spoProxy.removeRDF(tokenId, i, _POPairs[i]);
}
_maxPredicate[tokenId] = 0;
emit RemoveRDF(tokenId, oldData);
}
function rdfOf(uint256 tokenId) external view override onlySbt() returns (string memory) {
return _buildRdfString(tokenId);
}
// MARK: - Private
function _buildRdfString(uint256 tokenId) internal view returns (string memory) {
string memory rdf = "";
for (uint8 i = 1; i <= _maxPredicate[tokenId]; i++) {
string memory subject = string(abi.encodePacked(ENTITY_PREFIX, SOUL_PREFIX, Strings.toString(tokenId)));
string memory predicate = string(abi.encodePacked(PROPERTY_PREFIX, _predicates[i]));
string memory object = _spoProxy.getObject(tokenId, i, _POPairs[i]);
if (_isStringEmpty(object)) {
continue;
}
object = string(abi.encodePacked(ENTITY_PREFIX, _objectClasses[_POPairs[i]], CONCATENATION_CHARACTER, object));
// If it's the same subject as the previous iteration, use a semicolon to separate predicate-object pairs
if (!_isStringEmpty(rdf)) {
rdf = string(abi.encodePacked(rdf, TURTLE_LINE_SUFFIX, predicate, BLANK_SPACE, object));
} else {
rdf = string(abi.encodePacked(rdf, subject, BLANK_SPACE, predicate, BLANK_SPACE, object));
}
}
// Add a period at the end if rdf is not empty
if (!_isStringEmpty(rdf)) {
rdf = string(abi.encodePacked(rdf, TURTLE_END_SUFFIX));
}
return rdf;
}
function _isStringEmpty(string memory data) internal pure returns (bool) {
return bytes(data).length == 0;
}
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.12;
/**
* @title Semantic Soulbound Token
* Note: the EIP-165 identifier for this interface is 0xfbafb698
*/
interface ISemanticSBT {
/**
* @dev This emits when minting a Semantic Soulbound Token.
* @param tokenId The identifier for the Semantic Soulbound Token.
* @param rdfStatements The RDF statements for the Semantic Soulbound Token. An RDF statement is the statement made by an RDF triple.
*/
event CreateRDF (
uint256 indexed tokenId,
string rdfStatements
);
/**
* @dev This emits when updating the RDF data of Semantic Soulbound Token. RDF data is a collection of RDF statements that are used to represent information about resources.
* @param tokenId The identifier for the Semantic Soulbound Token.
* @param rdfStatements The RDF statements for the semantic soulbound token. An RDF statement is the statement made by an RDF triple.
*/
event UpdateRDF (
uint256 indexed tokenId,
string rdfStatements
);
/**
* @dev This emits when burning or revoking Semantic Soulbound Token.
* @param tokenId The identifier for the Semantic Soulbound Token.
* @param rdfStatements The RDF statements for the Semantic Soulbound Token. An RDF statement is the statement made by an RDF triple.
*/
event RemoveRDF (
uint256 indexed tokenId,
string rdfStatements
);
/**
* @dev Returns the RDF statements of the Semantic Soulbound Token. An RDF statement is the statement made by an RDF triple.
* @param tokenId The identifier for the Semantic Soulbound Token.
*/
function rdfOf(uint256 tokenId) external view returns (string memory);
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.7.0) (access/Ownable.sol)
pragma solidity ^0.8.0;
import "../utils/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 Throws if called by any account other than the owner.
*/
modifier onlyOwner() {
_checkOwner();
_;
}
/**
* @dev Returns the address of the current owner.
*/
function owner() public view virtual returns (address) {
return _owner;
}
/**
* @dev Throws if the sender is not the owner.
*/
function _checkOwner() internal view virtual {
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
// OpenZeppelin Contracts (last updated v4.8.0) (utils/Strings.sol)
pragma solidity ^0.8.0;
import "./math/Math.sol";
/**
* @dev String operations.
*/
library Strings {
bytes16 private constant _SYMBOLS = "0123456789abcdef";
uint8 private constant _ADDRESS_LENGTH = 20;
/**
* @dev Converts a `uint256` to its ASCII `string` decimal representation.
*/
function toString(uint256 value) internal pure returns (string memory) {
unchecked {
uint256 length = Math.log10(value) + 1;
string memory buffer = new string(length);
uint256 ptr;
/// @solidity memory-safe-assembly
assembly {
ptr := add(buffer, add(32, length))
}
while (true) {
ptr--;
/// @solidity memory-safe-assembly
assembly {
mstore8(ptr, byte(mod(value, 10), _SYMBOLS))
}
value /= 10;
if (value == 0) break;
}
return buffer;
}
}
/**
* @dev Converts a `uint256` to its ASCII `string` hexadecimal representation.
*/
function toHexString(uint256 value) internal pure returns (string memory) {
unchecked {
return toHexString(value, Math.log256(value) + 1);
}
}
/**
* @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] = _SYMBOLS[value & 0xf];
value >>= 4;
}
require(value == 0, "Strings: hex length insufficient");
return string(buffer);
}
/**
* @dev Converts an `address` with fixed length of 20 bytes to its not checksummed ASCII `string` hexadecimal representation.
*/
function toHexString(address addr) internal pure returns (string memory) {
return toHexString(uint256(uint160(addr)), _ADDRESS_LENGTH);
}
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.8.0) (security/ReentrancyGuard.sol)
pragma solidity ^0.8.0;
/**
* @dev Contract module that helps prevent reentrant calls to a function.
*
* Inheriting from `ReentrancyGuard` will make the {nonReentrant} modifier
* available, which can be applied to functions to make sure there are no nested
* (reentrant) calls to them.
*
* Note that because there is a single `nonReentrant` guard, functions marked as
* `nonReentrant` may not call one another. This can be worked around by making
* those functions `private`, and then adding `external` `nonReentrant` entry
* points to them.
*
* TIP: If you would like to learn more about reentrancy and alternative ways
* to protect against it, check out our blog post
* https://blog.openzeppelin.com/reentrancy-after-istanbul/[Reentrancy After Istanbul].
*/
abstract contract ReentrancyGuard {
// Booleans are more expensive than uint256 or any type that takes up a full
// word because each write operation emits an extra SLOAD to first read the
// slot's contents, replace the bits taken up by the boolean, and then write
// back. This is the compiler's defense against contract upgrades and
// pointer aliasing, and it cannot be disabled.
// The values being non-zero value makes deployment a bit more expensive,
// but in exchange the refund on every call to nonReentrant will be lower in
// amount. Since refunds are capped to a percentage of the total
// transaction's gas, it is best to keep them low in cases like this one, to
// increase the likelihood of the full refund coming into effect.
uint256 private constant _NOT_ENTERED = 1;
uint256 private constant _ENTERED = 2;
uint256 private _status;
constructor() {
_status = _NOT_ENTERED;
}
/**
* @dev Prevents a contract from calling itself, directly or indirectly.
* Calling a `nonReentrant` function from another `nonReentrant`
* function is not supported. It is possible to prevent this from happening
* by making the `nonReentrant` function external, and making it call a
* `private` function that does the actual work.
*/
modifier nonReentrant() {
_nonReentrantBefore();
_;
_nonReentrantAfter();
}
function _nonReentrantBefore() private {
// On the first call to nonReentrant, _status will be _NOT_ENTERED
require(_status != _ENTERED, "ReentrancyGuard: reentrant call");
// Any calls to nonReentrant after this point will fail
_status = _ENTERED;
}
function _nonReentrantAfter() private {
// By storing the original value once again, a refund is triggered (see
// https://eips.ethereum.org/EIPS/eip-2200)
_status = _NOT_ENTERED;
}
}
// 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 (last updated v4.8.0) (utils/math/Math.sol)
pragma solidity ^0.8.0;
/**
* @dev Standard math utilities missing in the Solidity language.
*/
library Math {
enum Rounding {
Down, // Toward negative infinity
Up, // Toward infinity
Zero // Toward zero
}
/**
* @dev Returns the largest of two numbers.
*/
function max(uint256 a, uint256 b) internal pure returns (uint256) {
return a > b ? a : b;
}
/**
* @dev Returns the smallest of two numbers.
*/
function min(uint256 a, uint256 b) internal pure returns (uint256) {
return a < b ? a : b;
}
/**
* @dev Returns the average of two numbers. The result is rounded towards
* zero.
*/
function average(uint256 a, uint256 b) internal pure returns (uint256) {
// (a + b) / 2 can overflow.
return (a & b) + (a ^ b) / 2;
}
/**
* @dev Returns the ceiling of the division of two numbers.
*
* This differs from standard division with `/` in that it rounds up instead
* of rounding down.
*/
function ceilDiv(uint256 a, uint256 b) internal pure returns (uint256) {
// (a + b - 1) / b can overflow on addition, so we distribute.
return a == 0 ? 0 : (a - 1) / b + 1;
}
/**
* @notice Calculates floor(x * y / denominator) with full precision. Throws if result overflows a uint256 or denominator == 0
* @dev Original credit to Remco Bloemen under MIT license (https://xn--2-umb.com/21/muldiv)
* with further edits by Uniswap Labs also under MIT license.
*/
function mulDiv(
uint256 x,
uint256 y,
uint256 denominator
) internal pure returns (uint256 result) {
unchecked {
// 512-bit multiply [prod1 prod0] = x * y. Compute the product mod 2^256 and mod 2^256 - 1, then use
// use the Chinese Remainder Theorem to reconstruct the 512 bit result. The result is stored in two 256
// variables such that product = prod1 * 2^256 + prod0.
uint256 prod0; // Least significant 256 bits of the product
uint256 prod1; // Most significant 256 bits of the product
assembly {
let mm := mulmod(x, y, not(0))
prod0 := mul(x, y)
prod1 := sub(sub(mm, prod0), lt(mm, prod0))
}
// Handle non-overflow cases, 256 by 256 division.
if (prod1 == 0) {
return prod0 / denominator;
}
// Make sure the result is less than 2^256. Also prevents denominator == 0.
require(denominator > prod1);
///////////////////////////////////////////////
// 512 by 256 division.
///////////////////////////////////////////////
// Make division exact by subtracting the remainder from [prod1 prod0].
uint256 remainder;
assembly {
// Compute remainder using mulmod.
remainder := mulmod(x, y, denominator)
// Subtract 256 bit number from 512 bit number.
prod1 := sub(prod1, gt(remainder, prod0))
prod0 := sub(prod0, remainder)
}
// Factor powers of two out of denominator and compute largest power of two divisor of denominator. Always >= 1.
// See https://cs.stackexchange.com/q/138556/92363.
// Does not overflow because the denominator cannot be zero at this stage in the function.
uint256 twos = denominator & (~denominator + 1);
assembly {
// Divide denominator by twos.
denominator := div(denominator, twos)
// Divide [prod1 prod0] by twos.
prod0 := div(prod0, twos)
// Flip twos such that it is 2^256 / twos. If twos is zero, then it becomes one.
twos := add(div(sub(0, twos), twos), 1)
}
// Shift in bits from prod1 into prod0.
prod0 |= prod1 * twos;
// Invert denominator mod 2^256. Now that denominator is an odd number, it has an inverse modulo 2^256 such
// that denominator * inv = 1 mod 2^256. Compute the inverse by starting with a seed that is correct for
// four bits. That is, denominator * inv = 1 mod 2^4.
uint256 inverse = (3 * denominator) ^ 2;
// Use the Newton-Raphson iteration to improve the precision. Thanks to Hensel's lifting lemma, this also works
// in modular arithmetic, doubling the correct bits in each step.
inverse *= 2 - denominator * inverse; // inverse mod 2^8
inverse *= 2 - denominator * inverse; // inverse mod 2^16
inverse *= 2 - denominator * inverse; // inverse mod 2^32
inverse *= 2 - denominator * inverse; // inverse mod 2^64
inverse *= 2 - denominator * inverse; // inverse mod 2^128
inverse *= 2 - denominator * inverse; // inverse mod 2^256
// Because the division is now exact we can divide by multiplying with the modular inverse of denominator.
// This will give us the correct result modulo 2^256. Since the preconditions guarantee that the outcome is
// less than 2^256, this is the final result. We don't need to compute the high bits of the result and prod1
// is no longer required.
result = prod0 * inverse;
return result;
}
}
/**
* @notice Calculates x * y / denominator with full precision, following the selected rounding direction.
*/
function mulDiv(
uint256 x,
uint256 y,
uint256 denominator,
Rounding rounding
) internal pure returns (uint256) {
uint256 result = mulDiv(x, y, denominator);
if (rounding == Rounding.Up && mulmod(x, y, denominator) > 0) {
result += 1;
}
return result;
}
/**
* @dev Returns the square root of a number. If the number is not a perfect square, the value is rounded down.
*
* Inspired by Henry S. Warren, Jr.'s "Hacker's Delight" (Chapter 11).
*/
function sqrt(uint256 a) internal pure returns (uint256) {
if (a == 0) {
return 0;
}
// For our first guess, we get the biggest power of 2 which is smaller than the square root of the target.
//
// We know that the "msb" (most significant bit) of our target number `a` is a power of 2 such that we have
// `msb(a) <= a < 2*msb(a)`. This value can be written `msb(a)=2**k` with `k=log2(a)`.
//
// This can be rewritten `2**log2(a) <= a < 2**(log2(a) + 1)`
// → `sqrt(2**k) <= sqrt(a) < sqrt(2**(k+1))`
// → `2**(k/2) <= sqrt(a) < 2**((k+1)/2) <= 2**(k/2 + 1)`
//
// Consequently, `2**(log2(a) / 2)` is a good first approximation of `sqrt(a)` with at least 1 correct bit.
uint256 result = 1 << (log2(a) >> 1);
// At this point `result` is an estimation with one bit of precision. We know the true value is a uint128,
// since it is the square root of a uint256. Newton's method converges quadratically (precision doubles at
// every iteration). We thus need at most 7 iteration to turn our partial result with one bit of precision
// into the expected uint128 result.
unchecked {
result = (result + a / result) >> 1;
result = (result + a / result) >> 1;
result = (result + a / result) >> 1;
result = (result + a / result) >> 1;
result = (result + a / result) >> 1;
result = (result + a / result) >> 1;
result = (result + a / result) >> 1;
return min(result, a / result);
}
}
/**
* @notice Calculates sqrt(a), following the selected rounding direction.
*/
function sqrt(uint256 a, Rounding rounding) internal pure returns (uint256) {
unchecked {
uint256 result = sqrt(a);
return result + (rounding == Rounding.Up && result * result < a ? 1 : 0);
}
}
/**
* @dev Return the log in base 2, rounded down, of a positive value.
* Returns 0 if given 0.
*/
function log2(uint256 value) internal pure returns (uint256) {
uint256 result = 0;
unchecked {
if (value >> 128 > 0) {
value >>= 128;
result += 128;
}
if (value >> 64 > 0) {
value >>= 64;
result += 64;
}
if (value >> 32 > 0) {
value >>= 32;
result += 32;
}
if (value >> 16 > 0) {
value >>= 16;
result += 16;
}
if (value >> 8 > 0) {
value >>= 8;
result += 8;
}
if (value >> 4 > 0) {
value >>= 4;
result += 4;
}
if (value >> 2 > 0) {
value >>= 2;
result += 2;
}
if (value >> 1 > 0) {
result += 1;
}
}
return result;
}
/**
* @dev Return the log in base 2, following the selected rounding direction, of a positive value.
* Returns 0 if given 0.
*/
function log2(uint256 value, Rounding rounding) internal pure returns (uint256) {
unchecked {
uint256 result = log2(value);
return result + (rounding == Rounding.Up && 1 << result < value ? 1 : 0);
}
}
/**
* @dev Return the log in base 10, rounded down, of a positive value.
* Returns 0 if given 0.
*/
function log10(uint256 value) internal pure returns (uint256) {
uint256 result = 0;
unchecked {
if (value >= 10**64) {
value /= 10**64;
result += 64;
}
if (value >= 10**32) {
value /= 10**32;
result += 32;
}
if (value >= 10**16) {
value /= 10**16;
result += 16;
}
if (value >= 10**8) {
value /= 10**8;
result += 8;
}
if (value >= 10**4) {
value /= 10**4;
result += 4;
}
if (value >= 10**2) {
value /= 10**2;
result += 2;
}
if (value >= 10**1) {
result += 1;
}
}
return result;
}
/**
* @dev Return the log in base 10, following the selected rounding direction, of a positive value.
* Returns 0 if given 0.
*/
function log10(uint256 value, Rounding rounding) internal pure returns (uint256) {
unchecked {
uint256 result = log10(value);
return result + (rounding == Rounding.Up && 10**result < value ? 1 : 0);
}
}
/**
* @dev Return the log in base 256, rounded down, of a positive value.
* Returns 0 if given 0.
*
* Adding one to the result gives the number of pairs of hex symbols needed to represent `value` as a hex string.
*/
function log256(uint256 value) internal pure returns (uint256) {
uint256 result = 0;
unchecked {
if (value >> 128 > 0) {
value >>= 128;
result += 16;
}
if (value >> 64 > 0) {
value >>= 64;
result += 8;
}
if (value >> 32 > 0) {
value >>= 32;
result += 4;
}
if (value >> 16 > 0) {
value >>= 16;
result += 2;
}
if (value >> 8 > 0) {
result += 1;
}
}
return result;
}
/**
* @dev Return the log in base 10, following the selected rounding direction, of a positive value.
* Returns 0 if given 0.
*/
function log256(uint256 value, Rounding rounding) internal pure returns (uint256) {
unchecked {
uint256 result = log256(value);
return result + (rounding == Rounding.Up && 1 << (result * 8) < value ? 1 : 0);
}
}
}