//SPDX-License-Identifier: UNLICENSEDpragmasolidity ^0.8.0;abstractcontractOwnable{
eventOwnershipTransferred(addressindexed user, addressindexed newOwner);
errorUnauthorized();
errorInvalidOwner();
addresspublic owner;
modifieronlyOwner() virtual{
if (msg.sender!= owner) revert Unauthorized();
_;
}
constructor(address _owner) {
if (_owner ==address(0)) revert InvalidOwner();
owner = _owner;
emit OwnershipTransferred(address(0), _owner);
}
functiontransferOwnership(address _owner) publicvirtualonlyOwner{
if (_owner ==address(0)) revert InvalidOwner();
owner = _owner;
emit OwnershipTransferred(msg.sender, _owner);
}
functionrevokeOwnership() publicvirtualonlyOwner{
owner =address(0);
emit OwnershipTransferred(msg.sender, address(0));
}
}
abstractcontractERC721Receiver{
functiononERC721Received(address,
address,
uint256,
bytescalldata) externalvirtualreturns (bytes4) {
return ERC721Receiver.onERC721Received.selector;
}
}
/// @notice ERC404/// A gas-efficient, mixed ERC20 / ERC721 implementation/// with native liquidity and fractionalization.////// This is an experimental standard designed to integrate/// with pre-existing ERC20 / ERC721 support as smoothly as/// possible.////// @dev In order to support full functionality of ERC20 and ERC721/// supply assumptions are made that slightly constraint usage./// Ensure decimals are sufficiently large (standard 18 recommended)/// as ids are effectively encoded in the lowest range of amounts.////// NFTs are spent on ERC20 functions in a FILO queue, this is by/// design.///abstractcontractERC404isOwnable{
// EventseventERC20Transfer(addressindexedfrom,
addressindexed to,
uint256 amount
);
eventApproval(addressindexed owner,
addressindexed spender,
uint256 amount
);
eventTransfer(addressindexedfrom,
addressindexed to,
uint256indexed id
);
eventERC721Approval(addressindexed owner,
addressindexed spender,
uint256indexed id
);
eventApprovalForAll(addressindexed owner,
addressindexed operator,
bool approved
);
// ErrorserrorNotFound();
errorAlreadyExists();
errorInvalidRecipient();
errorInvalidSender();
errorUnsafeRecipient();
// Metadata/// @dev Token namestringpublic name;
/// @dev Token symbolstringpublic symbol;
/// @dev Decimals for fractional representationuint8publicimmutable decimals;
/// @dev Total supply in fractionalized representationuint256publicimmutable totalSupply;
/// @dev Current mint counter, monotonically increasing to ensure accurate ownershipuint256public minted;
// Mappings/// @dev Balance of user in fractional representationmapping(address=>uint256) public balanceOf;
/// @dev Allowance of user in fractional representationmapping(address=>mapping(address=>uint256)) public allowance;
/// @dev Approval in native representaionmapping(uint256=>address) public getApproved;
/// @dev Approval for all in native representationmapping(address=>mapping(address=>bool)) public isApprovedForAll;
/// @dev Owner of id in native representationmapping(uint256=>address) internal _ownerOf;
/// @dev Array of owned ids in native representationmapping(address=>uint256[]) internal _owned;
/// @dev Tracks indices for the _owned mappingmapping(uint256=>uint256) internal _ownedIndex;
/// @dev Addresses whitelisted from minting / burning for gas savings (pairs, routers, etc)mapping(address=>bool) public whitelist;
// Constructorconstructor(stringmemory _name,
stringmemory _symbol,
uint8 _decimals,
uint256 _totalNativeSupply,
address _owner
) Ownable(_owner) {
name = _name;
symbol = _symbol;
decimals = _decimals;
totalSupply = _totalNativeSupply * (10** decimals);
}
/// @notice Initialization function to set pairs / etc/// saving gas by avoiding mint / burn on unnecessary targetsfunctionsetWhitelist(address target, bool state) publiconlyOwner{
// Prevents minting new NFTs by simply toggling the whitelist status.// This ensures that the capability to mint new tokens cannot be exploited// by reopen whitelist state.if (state) {
uint256[] memory ownedList = _owned[target];
for (uint256 i =0; i < ownedList.length; i++) {
_burn(target);
}
}
whitelist[target] = state;
}
/// @notice Function to find owner of a given native tokenfunctionownerOf(uint256 id) publicviewvirtualreturns (address owner) {
owner = _ownerOf[id];
if (owner ==address(0)) {
revert NotFound();
}
}
/// @notice tokenURI must be implemented by child contractfunctiontokenURI(uint256 id) publicviewvirtualreturns (stringmemory);
/// @notice Function for token approvals/// @dev This function assumes id / native if amount less than or equal to current max idfunctionapprove(address spender,
uint256 amountOrId
) publicvirtualreturns (bool) {
if (amountOrId <= minted && amountOrId >0) {
address owner = _ownerOf[amountOrId];
if (msg.sender!= owner &&!isApprovedForAll[owner][msg.sender]) {
revert Unauthorized();
}
getApproved[amountOrId] = spender;
emit Approval(owner, spender, amountOrId);
} else {
allowance[msg.sender][spender] = amountOrId;
emit Approval(msg.sender, spender, amountOrId);
}
returntrue;
}
/// @notice Function native approvalsfunctionsetApprovalForAll(address operator, bool approved) publicvirtual{
isApprovedForAll[msg.sender][operator] = approved;
emit ApprovalForAll(msg.sender, operator, approved);
}
/// @notice Function for mixed transfers/// @dev This function assumes id / native if amount less than or equal to current max idfunctiontransferFrom(addressfrom,
address to,
uint256 amountOrId
) publicvirtual{
if (amountOrId <= minted) {
if (from!= _ownerOf[amountOrId]) {
revert InvalidSender();
}
if (to ==address(0)) {
revert InvalidRecipient();
}
if (
msg.sender!=from&&!isApprovedForAll[from][msg.sender] &&msg.sender!= getApproved[amountOrId]
) {
revert Unauthorized();
}
if (whitelist[to]) {
revert InvalidRecipient();
}
balanceOf[from] -= _getUnit();
unchecked {
balanceOf[to] += _getUnit();
}
_ownerOf[amountOrId] = to;
delete getApproved[amountOrId];
// update _owned for senderuint256 updatedId = _owned[from][_owned[from].length-1];
_owned[from][_ownedIndex[amountOrId]] = updatedId;
// pop
_owned[from].pop();
// update index for the moved id
_ownedIndex[updatedId] = _ownedIndex[amountOrId];
// push token to to owned
_owned[to].push(amountOrId);
// update index for to owned
_ownedIndex[amountOrId] = _owned[to].length-1;
emit Transfer(from, to, amountOrId);
emit ERC20Transfer(from, to, _getUnit());
} else {
uint256 allowed = allowance[from][msg.sender];
if (allowed !=type(uint256).max)
allowance[from][msg.sender] = allowed - amountOrId;
_transfer(from, to, amountOrId);
}
}
/// @notice Function for fractional transfersfunctiontransfer(address to,
uint256 amount
) publicvirtualreturns (bool) {
return _transfer(msg.sender, to, amount);
}
/// @notice Function for native transfers with contract supportfunctionsafeTransferFrom(addressfrom,
address to,
uint256 id
) publicvirtual{
transferFrom(from, to, id);
if (
to.code.length!=0&&
ERC721Receiver(to).onERC721Received(msg.sender, from, id, "") !=
ERC721Receiver.onERC721Received.selector
) {
revert UnsafeRecipient();
}
}
/// @notice Function for native transfers with contract support and callback datafunctionsafeTransferFrom(addressfrom,
address to,
uint256 id,
bytescalldata data
) publicvirtual{
transferFrom(from, to, id);
if (
to.code.length!=0&&
ERC721Receiver(to).onERC721Received(msg.sender, from, id, data) !=
ERC721Receiver.onERC721Received.selector
) {
revert UnsafeRecipient();
}
}
/// @notice Internal function for fractional transfersfunction_transfer(addressfrom,
address to,
uint256 amount
) internalreturns (bool) {
uint256 unit = _getUnit();
uint256 balanceBeforeSender = balanceOf[from];
uint256 balanceBeforeReceiver = balanceOf[to];
balanceOf[from] -= amount;
unchecked {
balanceOf[to] += amount;
}
// Skip burn for certain addresses to save gasif (!whitelist[from]) {
uint256 tokens_to_burn = (balanceBeforeSender / unit) -
(balanceOf[from] / unit);
for (uint256 i =0; i < tokens_to_burn; i++) {
_burn(from);
}
}
// Skip minting for certain addresses to save gasif (!whitelist[to]) {
uint256 tokens_to_mint = (balanceOf[to] / unit) -
(balanceBeforeReceiver / unit);
for (uint256 i =0; i < tokens_to_mint; i++) {
_mint(to);
}
}
emit ERC20Transfer(from, to, amount);
returntrue;
}
// Internal utility logicfunction_getUnit() internalviewreturns (uint256) {
return10** decimals;
}
function_mint(address to) internalvirtual{
if (to ==address(0)) {
revert InvalidRecipient();
}
unchecked {
minted++;
}
uint256 id = minted;
if (_ownerOf[id] !=address(0)) {
revert AlreadyExists();
}
_ownerOf[id] = to;
_owned[to].push(id);
_ownedIndex[id] = _owned[to].length-1;
emit Transfer(address(0), to, id);
}
function_burn(addressfrom) internalvirtual{
if (from==address(0)) {
revert InvalidSender();
}
uint256 id = _owned[from][_owned[from].length-1];
_owned[from].pop();
delete _ownedIndex[id];
delete _ownerOf[id];
delete getApproved[id];
emit Transfer(from, address(0), id);
}
function_setNameSymbol(stringmemory _name,
stringmemory _symbol
) internal{
name = _name;
symbol = _symbol;
}
}
Contract Source Code
File 3 of 5: Math.sol
// SPDX-License-Identifier: MIT// OpenZeppelin Contracts (last updated v5.0.0) (utils/math/Math.sol)pragmasolidity ^0.8.20;/**
* @dev Standard math utilities missing in the Solidity language.
*/libraryMath{
/**
* @dev Muldiv operation overflow.
*/errorMathOverflowedMulDiv();
enumRounding {
Floor, // Toward negative infinity
Ceil, // Toward positive infinity
Trunc, // Toward zero
Expand // Away from zero
}
/**
* @dev Returns the addition of two unsigned integers, with an overflow flag.
*/functiontryAdd(uint256 a, uint256 b) internalpurereturns (bool, uint256) {
unchecked {
uint256 c = a + b;
if (c < a) return (false, 0);
return (true, c);
}
}
/**
* @dev Returns the subtraction of two unsigned integers, with an overflow flag.
*/functiontrySub(uint256 a, uint256 b) internalpurereturns (bool, uint256) {
unchecked {
if (b > a) return (false, 0);
return (true, a - b);
}
}
/**
* @dev Returns the multiplication of two unsigned integers, with an overflow flag.
*/functiontryMul(uint256 a, uint256 b) internalpurereturns (bool, uint256) {
unchecked {
// Gas optimization: this is cheaper than requiring 'a' not being zero, but the// benefit is lost if 'b' is also tested.// See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522if (a ==0) return (true, 0);
uint256 c = a * b;
if (c / a != b) return (false, 0);
return (true, c);
}
}
/**
* @dev Returns the division of two unsigned integers, with a division by zero flag.
*/functiontryDiv(uint256 a, uint256 b) internalpurereturns (bool, uint256) {
unchecked {
if (b ==0) return (false, 0);
return (true, a / b);
}
}
/**
* @dev Returns the remainder of dividing two unsigned integers, with a division by zero flag.
*/functiontryMod(uint256 a, uint256 b) internalpurereturns (bool, uint256) {
unchecked {
if (b ==0) return (false, 0);
return (true, a % b);
}
}
/**
* @dev Returns the largest of two numbers.
*/functionmax(uint256 a, uint256 b) internalpurereturns (uint256) {
return a > b ? a : b;
}
/**
* @dev Returns the smallest of two numbers.
*/functionmin(uint256 a, uint256 b) internalpurereturns (uint256) {
return a < b ? a : b;
}
/**
* @dev Returns the average of two numbers. The result is rounded towards
* zero.
*/functionaverage(uint256 a, uint256 b) internalpurereturns (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 towards infinity instead
* of rounding towards zero.
*/functionceilDiv(uint256 a, uint256 b) internalpurereturns (uint256) {
if (b ==0) {
// Guarantee the same behavior as in a regular Solidity division.return a / b;
}
// (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.
*/functionmulDiv(uint256 x, uint256 y, uint256 denominator) internalpurereturns (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 = x * y; // Least significant 256 bits of the productuint256 prod1; // Most significant 256 bits of the productassembly {
let mm :=mulmod(x, y, not(0))
prod1 :=sub(sub(mm, prod0), lt(mm, prod0))
}
// Handle non-overflow cases, 256 by 256 division.if (prod1 ==0) {
// Solidity will revert if denominator == 0, unlike the div opcode on its own.// The surrounding unchecked block does not change this fact.// See https://docs.soliditylang.org/en/latest/control-structures.html#checked-or-unchecked-arithmetic.return prod0 / denominator;
}
// Make sure the result is less than 2^256. Also prevents denominator == 0.if (denominator <= prod1) {
revert MathOverflowedMulDiv();
}
///////////////////////////////////////////////// 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.uint256 twos = denominator & (0- denominator);
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.
*/functionmulDiv(uint256 x, uint256 y, uint256 denominator, Rounding rounding) internalpurereturns (uint256) {
uint256 result = mulDiv(x, y, denominator);
if (unsignedRoundsUp(rounding) &&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
* towards zero.
*
* Inspired by Henry S. Warren, Jr.'s "Hacker's Delight" (Chapter 11).
*/functionsqrt(uint256 a) internalpurereturns (uint256) {
if (a ==0) {
return0;
}
// 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.
*/functionsqrt(uint256 a, Rounding rounding) internalpurereturns (uint256) {
unchecked {
uint256 result = sqrt(a);
return result + (unsignedRoundsUp(rounding) && result * result < a ? 1 : 0);
}
}
/**
* @dev Return the log in base 2 of a positive value rounded towards zero.
* Returns 0 if given 0.
*/functionlog2(uint256 value) internalpurereturns (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.
*/functionlog2(uint256 value, Rounding rounding) internalpurereturns (uint256) {
unchecked {
uint256 result =log2(value);
return result + (unsignedRoundsUp(rounding) &&1<< result < value ? 1 : 0);
}
}
/**
* @dev Return the log in base 10 of a positive value rounded towards zero.
* Returns 0 if given 0.
*/functionlog10(uint256 value) internalpurereturns (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.
*/functionlog10(uint256 value, Rounding rounding) internalpurereturns (uint256) {
unchecked {
uint256 result = log10(value);
return result + (unsignedRoundsUp(rounding) &&10** result < value ? 1 : 0);
}
}
/**
* @dev Return the log in base 256 of a positive value rounded towards zero.
* 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.
*/functionlog256(uint256 value) internalpurereturns (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 256, following the selected rounding direction, of a positive value.
* Returns 0 if given 0.
*/functionlog256(uint256 value, Rounding rounding) internalpurereturns (uint256) {
unchecked {
uint256 result = log256(value);
return result + (unsignedRoundsUp(rounding) &&1<< (result <<3) < value ? 1 : 0);
}
}
/**
* @dev Returns whether a provided rounding mode is considered rounding up for unsigned integers.
*/functionunsignedRoundsUp(Rounding rounding) internalpurereturns (bool) {
returnuint8(rounding) %2==1;
}
}
Contract Source Code
File 4 of 5: SignedMath.sol
// SPDX-License-Identifier: MIT// OpenZeppelin Contracts (last updated v5.0.0) (utils/math/SignedMath.sol)pragmasolidity ^0.8.20;/**
* @dev Standard signed math utilities missing in the Solidity language.
*/librarySignedMath{
/**
* @dev Returns the largest of two signed numbers.
*/functionmax(int256 a, int256 b) internalpurereturns (int256) {
return a > b ? a : b;
}
/**
* @dev Returns the smallest of two signed numbers.
*/functionmin(int256 a, int256 b) internalpurereturns (int256) {
return a < b ? a : b;
}
/**
* @dev Returns the average of two signed numbers without overflow.
* The result is rounded towards zero.
*/functionaverage(int256 a, int256 b) internalpurereturns (int256) {
// Formula from the book "Hacker's Delight"int256 x = (a & b) + ((a ^ b) >>1);
return x + (int256(uint256(x) >>255) & (a ^ b));
}
/**
* @dev Returns the absolute unsigned value of a signed value.
*/functionabs(int256 n) internalpurereturns (uint256) {
unchecked {
// must be unchecked in order to support `n = type(int256).min`returnuint256(n >=0 ? n : -n);
}
}
}
Contract Source Code
File 5 of 5: Strings.sol
// SPDX-License-Identifier: MIT// OpenZeppelin Contracts (last updated v5.0.0) (utils/Strings.sol)pragmasolidity ^0.8.20;import {Math} from"./math/Math.sol";
import {SignedMath} from"./math/SignedMath.sol";
/**
* @dev String operations.
*/libraryStrings{
bytes16privateconstant HEX_DIGITS ="0123456789abcdef";
uint8privateconstant ADDRESS_LENGTH =20;
/**
* @dev The `value` string doesn't fit in the specified `length`.
*/errorStringsInsufficientHexLength(uint256 value, uint256 length);
/**
* @dev Converts a `uint256` to its ASCII `string` decimal representation.
*/functiontoString(uint256 value) internalpurereturns (stringmemory) {
unchecked {
uint256 length = Math.log10(value) +1;
stringmemory buffer =newstring(length);
uint256 ptr;
/// @solidity memory-safe-assemblyassembly {
ptr :=add(buffer, add(32, length))
}
while (true) {
ptr--;
/// @solidity memory-safe-assemblyassembly {
mstore8(ptr, byte(mod(value, 10), HEX_DIGITS))
}
value /=10;
if (value ==0) break;
}
return buffer;
}
}
/**
* @dev Converts a `int256` to its ASCII `string` decimal representation.
*/functiontoStringSigned(int256 value) internalpurereturns (stringmemory) {
returnstring.concat(value <0 ? "-" : "", toString(SignedMath.abs(value)));
}
/**
* @dev Converts a `uint256` to its ASCII `string` hexadecimal representation.
*/functiontoHexString(uint256 value) internalpurereturns (stringmemory) {
unchecked {
return toHexString(value, Math.log256(value) +1);
}
}
/**
* @dev Converts a `uint256` to its ASCII `string` hexadecimal representation with fixed length.
*/functiontoHexString(uint256 value, uint256 length) internalpurereturns (stringmemory) {
uint256 localValue = value;
bytesmemory buffer =newbytes(2* length +2);
buffer[0] ="0";
buffer[1] ="x";
for (uint256 i =2* length +1; i >1; --i) {
buffer[i] = HEX_DIGITS[localValue &0xf];
localValue >>=4;
}
if (localValue !=0) {
revert StringsInsufficientHexLength(value, length);
}
returnstring(buffer);
}
/**
* @dev Converts an `address` with fixed length of 20 bytes to its not checksummed ASCII `string` hexadecimal
* representation.
*/functiontoHexString(address addr) internalpurereturns (stringmemory) {
return toHexString(uint256(uint160(addr)), ADDRESS_LENGTH);
}
/**
* @dev Returns true if the two strings are equal.
*/functionequal(stringmemory a, stringmemory b) internalpurereturns (bool) {
returnbytes(a).length==bytes(b).length&&keccak256(bytes(a)) ==keccak256(bytes(b));
}
}