// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.2.0) (utils/Strings.sol)
pragma solidity ^0.8.20;
import {Math} from "./Math.sol";
import {SafeCast} from "./SafeCast.sol";
import {SignedMath} from "./SignedMath.sol";
/**
* @dev String operations.
*/
library Strings {
using SafeCast for *;
bytes16 private constant HEX_DIGITS = "0123456789abcdef";
uint8 private constant ADDRESS_LENGTH = 20;
uint256 private constant SPECIAL_CHARS_LOOKUP =
(1 << 0x08) | // backspace
(1 << 0x09) | // tab
(1 << 0x0a) | // newline
(1 << 0x0c) | // form feed
(1 << 0x0d) | // carriage return
(1 << 0x22) | // double quote
(1 << 0x5c); // backslash
/**
* @dev The `value` string doesn't fit in the specified `length`.
*/
error StringsInsufficientHexLength(uint256 value, uint256 length);
/**
* @dev The string being parsed contains characters that are not in scope of the given base.
*/
error StringsInvalidChar();
/**
* @dev The string being parsed is not a properly formatted address.
*/
error StringsInvalidAddressFormat();
/**
* @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;
assembly ("memory-safe") {
ptr := add(buffer, add(32, length))
}
while (true) {
ptr--;
assembly ("memory-safe") {
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.
*/
function toStringSigned(int256 value) internal pure returns (string memory) {
return string.concat(value < 0 ? "-" : "", toString(SignedMath.abs(value)));
}
/**
* @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) {
uint256 localValue = value;
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_DIGITS[localValue & 0xf];
localValue >>= 4;
}
if (localValue != 0) {
revert StringsInsufficientHexLength(value, length);
}
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);
}
/**
* @dev Converts an `address` with fixed length of 20 bytes to its checksummed ASCII `string` hexadecimal
* representation, according to EIP-55.
*/
function toChecksumHexString(address addr) internal pure returns (string memory) {
bytes memory buffer = bytes(toHexString(addr));
// hash the hex part of buffer (skip length + 2 bytes, length 40)
uint256 hashValue;
assembly ("memory-safe") {
hashValue := shr(96, keccak256(add(buffer, 0x22), 40))
}
for (uint256 i = 41; i > 1; --i) {
// possible values for buffer[i] are 48 (0) to 57 (9) and 97 (a) to 102 (f)
if (hashValue & 0xf > 7 && uint8(buffer[i]) > 96) {
// case shift by xoring with 0x20
buffer[i] ^= 0x20;
}
hashValue >>= 4;
}
return string(buffer);
}
/**
* @dev Returns true if the two strings are equal.
*/
function equal(string memory a, string memory b) internal pure returns (bool) {
return bytes(a).length == bytes(b).length && keccak256(bytes(a)) == keccak256(bytes(b));
}
/**
* @dev Parse a decimal string and returns the value as a `uint256`.
*
* Requirements:
* - The string must be formatted as `[0-9]*`
* - The result must fit into an `uint256` type
*/
function parseUint(string memory input) internal pure returns (uint256) {
return parseUint(input, 0, bytes(input).length);
}
/**
* @dev Variant of {parseUint-string} that parses a substring of `input` located between position `begin` (included) and
* `end` (excluded).
*
* Requirements:
* - The substring must be formatted as `[0-9]*`
* - The result must fit into an `uint256` type
*/
function parseUint(string memory input, uint256 begin, uint256 end) internal pure returns (uint256) {
(bool success, uint256 value) = tryParseUint(input, begin, end);
if (!success) revert StringsInvalidChar();
return value;
}
/**
* @dev Variant of {parseUint-string} that returns false if the parsing fails because of an invalid character.
*
* NOTE: This function will revert if the result does not fit in a `uint256`.
*/
function tryParseUint(string memory input) internal pure returns (bool success, uint256 value) {
return _tryParseUintUncheckedBounds(input, 0, bytes(input).length);
}
/**
* @dev Variant of {parseUint-string-uint256-uint256} that returns false if the parsing fails because of an invalid
* character.
*
* NOTE: This function will revert if the result does not fit in a `uint256`.
*/
function tryParseUint(
string memory input,
uint256 begin,
uint256 end
) internal pure returns (bool success, uint256 value) {
if (end > bytes(input).length || begin > end) return (false, 0);
return _tryParseUintUncheckedBounds(input, begin, end);
}
/**
* @dev Implementation of {tryParseUint-string-uint256-uint256} that does not check bounds. Caller should make sure that
* `begin <= end <= input.length`. Other inputs would result in undefined behavior.
*/
function _tryParseUintUncheckedBounds(
string memory input,
uint256 begin,
uint256 end
) private pure returns (bool success, uint256 value) {
bytes memory buffer = bytes(input);
uint256 result = 0;
for (uint256 i = begin; i < end; ++i) {
uint8 chr = _tryParseChr(bytes1(_unsafeReadBytesOffset(buffer, i)));
if (chr > 9) return (false, 0);
result *= 10;
result += chr;
}
return (true, result);
}
/**
* @dev Parse a decimal string and returns the value as a `int256`.
*
* Requirements:
* - The string must be formatted as `[-+]?[0-9]*`
* - The result must fit in an `int256` type.
*/
function parseInt(string memory input) internal pure returns (int256) {
return parseInt(input, 0, bytes(input).length);
}
/**
* @dev Variant of {parseInt-string} that parses a substring of `input` located between position `begin` (included) and
* `end` (excluded).
*
* Requirements:
* - The substring must be formatted as `[-+]?[0-9]*`
* - The result must fit in an `int256` type.
*/
function parseInt(string memory input, uint256 begin, uint256 end) internal pure returns (int256) {
(bool success, int256 value) = tryParseInt(input, begin, end);
if (!success) revert StringsInvalidChar();
return value;
}
/**
* @dev Variant of {parseInt-string} that returns false if the parsing fails because of an invalid character or if
* the result does not fit in a `int256`.
*
* NOTE: This function will revert if the absolute value of the result does not fit in a `uint256`.
*/
function tryParseInt(string memory input) internal pure returns (bool success, int256 value) {
return _tryParseIntUncheckedBounds(input, 0, bytes(input).length);
}
uint256 private constant ABS_MIN_INT256 = 2 ** 255;
/**
* @dev Variant of {parseInt-string-uint256-uint256} that returns false if the parsing fails because of an invalid
* character or if the result does not fit in a `int256`.
*
* NOTE: This function will revert if the absolute value of the result does not fit in a `uint256`.
*/
function tryParseInt(
string memory input,
uint256 begin,
uint256 end
) internal pure returns (bool success, int256 value) {
if (end > bytes(input).length || begin > end) return (false, 0);
return _tryParseIntUncheckedBounds(input, begin, end);
}
/**
* @dev Implementation of {tryParseInt-string-uint256-uint256} that does not check bounds. Caller should make sure that
* `begin <= end <= input.length`. Other inputs would result in undefined behavior.
*/
function _tryParseIntUncheckedBounds(
string memory input,
uint256 begin,
uint256 end
) private pure returns (bool success, int256 value) {
bytes memory buffer = bytes(input);
// Check presence of a negative sign.
bytes1 sign = begin == end ? bytes1(0) : bytes1(_unsafeReadBytesOffset(buffer, begin)); // don't do out-of-bound (possibly unsafe) read if sub-string is empty
bool positiveSign = sign == bytes1("+");
bool negativeSign = sign == bytes1("-");
uint256 offset = (positiveSign || negativeSign).toUint();
(bool absSuccess, uint256 absValue) = tryParseUint(input, begin + offset, end);
if (absSuccess && absValue < ABS_MIN_INT256) {
return (true, negativeSign ? -int256(absValue) : int256(absValue));
} else if (absSuccess && negativeSign && absValue == ABS_MIN_INT256) {
return (true, type(int256).min);
} else return (false, 0);
}
/**
* @dev Parse a hexadecimal string (with or without "0x" prefix), and returns the value as a `uint256`.
*
* Requirements:
* - The string must be formatted as `(0x)?[0-9a-fA-F]*`
* - The result must fit in an `uint256` type.
*/
function parseHexUint(string memory input) internal pure returns (uint256) {
return parseHexUint(input, 0, bytes(input).length);
}
/**
* @dev Variant of {parseHexUint-string} that parses a substring of `input` located between position `begin` (included) and
* `end` (excluded).
*
* Requirements:
* - The substring must be formatted as `(0x)?[0-9a-fA-F]*`
* - The result must fit in an `uint256` type.
*/
function parseHexUint(string memory input, uint256 begin, uint256 end) internal pure returns (uint256) {
(bool success, uint256 value) = tryParseHexUint(input, begin, end);
if (!success) revert StringsInvalidChar();
return value;
}
/**
* @dev Variant of {parseHexUint-string} that returns false if the parsing fails because of an invalid character.
*
* NOTE: This function will revert if the result does not fit in a `uint256`.
*/
function tryParseHexUint(string memory input) internal pure returns (bool success, uint256 value) {
return _tryParseHexUintUncheckedBounds(input, 0, bytes(input).length);
}
/**
* @dev Variant of {parseHexUint-string-uint256-uint256} that returns false if the parsing fails because of an
* invalid character.
*
* NOTE: This function will revert if the result does not fit in a `uint256`.
*/
function tryParseHexUint(
string memory input,
uint256 begin,
uint256 end
) internal pure returns (bool success, uint256 value) {
if (end > bytes(input).length || begin > end) return (false, 0);
return _tryParseHexUintUncheckedBounds(input, begin, end);
}
/**
* @dev Implementation of {tryParseHexUint-string-uint256-uint256} that does not check bounds. Caller should make sure that
* `begin <= end <= input.length`. Other inputs would result in undefined behavior.
*/
function _tryParseHexUintUncheckedBounds(
string memory input,
uint256 begin,
uint256 end
) private pure returns (bool success, uint256 value) {
bytes memory buffer = bytes(input);
// skip 0x prefix if present
bool hasPrefix = (end > begin + 1) && bytes2(_unsafeReadBytesOffset(buffer, begin)) == bytes2("0x"); // don't do out-of-bound (possibly unsafe) read if sub-string is empty
uint256 offset = hasPrefix.toUint() * 2;
uint256 result = 0;
for (uint256 i = begin + offset; i < end; ++i) {
uint8 chr = _tryParseChr(bytes1(_unsafeReadBytesOffset(buffer, i)));
if (chr > 15) return (false, 0);
result *= 16;
unchecked {
// Multiplying by 16 is equivalent to a shift of 4 bits (with additional overflow check).
// This guarantees that adding a value < 16 will not cause an overflow, hence the unchecked.
result += chr;
}
}
return (true, result);
}
/**
* @dev Parse a hexadecimal string (with or without "0x" prefix), and returns the value as an `address`.
*
* Requirements:
* - The string must be formatted as `(0x)?[0-9a-fA-F]{40}`
*/
function parseAddress(string memory input) internal pure returns (address) {
return parseAddress(input, 0, bytes(input).length);
}
/**
* @dev Variant of {parseAddress-string} that parses a substring of `input` located between position `begin` (included) and
* `end` (excluded).
*
* Requirements:
* - The substring must be formatted as `(0x)?[0-9a-fA-F]{40}`
*/
function parseAddress(string memory input, uint256 begin, uint256 end) internal pure returns (address) {
(bool success, address value) = tryParseAddress(input, begin, end);
if (!success) revert StringsInvalidAddressFormat();
return value;
}
/**
* @dev Variant of {parseAddress-string} that returns false if the parsing fails because the input is not a properly
* formatted address. See {parseAddress-string} requirements.
*/
function tryParseAddress(string memory input) internal pure returns (bool success, address value) {
return tryParseAddress(input, 0, bytes(input).length);
}
/**
* @dev Variant of {parseAddress-string-uint256-uint256} that returns false if the parsing fails because input is not a properly
* formatted address. See {parseAddress-string-uint256-uint256} requirements.
*/
function tryParseAddress(
string memory input,
uint256 begin,
uint256 end
) internal pure returns (bool success, address value) {
if (end > bytes(input).length || begin > end) return (false, address(0));
bool hasPrefix = (end > begin + 1) && bytes2(_unsafeReadBytesOffset(bytes(input), begin)) == bytes2("0x"); // don't do out-of-bound (possibly unsafe) read if sub-string is empty
uint256 expectedLength = 40 + hasPrefix.toUint() * 2;
// check that input is the correct length
if (end - begin == expectedLength) {
// length guarantees that this does not overflow, and value is at most type(uint160).max
(bool s, uint256 v) = _tryParseHexUintUncheckedBounds(input, begin, end);
return (s, address(uint160(v)));
} else {
return (false, address(0));
}
}
function _tryParseChr(bytes1 chr) private pure returns (uint8) {
uint8 value = uint8(chr);
// Try to parse `chr`:
// - Case 1: [0-9]
// - Case 2: [a-f]
// - Case 3: [A-F]
// - otherwise not supported
unchecked {
if (value > 47 && value < 58) value -= 48;
else if (value > 96 && value < 103) value -= 87;
else if (value > 64 && value < 71) value -= 55;
else return type(uint8).max;
}
return value;
}
/**
* @dev Escape special characters in JSON strings. This can be useful to prevent JSON injection in NFT metadata.
*
* WARNING: This function should only be used in double quoted JSON strings. Single quotes are not escaped.
*/
function escapeJSON(string memory input) internal pure returns (string memory) {
bytes memory buffer = bytes(input);
bytes memory output = new bytes(2 * buffer.length); // worst case scenario
uint256 outputLength = 0;
for (uint256 i; i < buffer.length; ++i) {
bytes1 char = bytes1(_unsafeReadBytesOffset(buffer, i));
if (((SPECIAL_CHARS_LOOKUP & (1 << uint8(char))) != 0)) {
output[outputLength++] = "\\";
if (char == 0x08) output[outputLength++] = "b";
else if (char == 0x09) output[outputLength++] = "t";
else if (char == 0x0a) output[outputLength++] = "n";
else if (char == 0x0c) output[outputLength++] = "f";
else if (char == 0x0d) output[outputLength++] = "r";
else if (char == 0x5c) output[outputLength++] = "\\";
else if (char == 0x22) {
// solhint-disable-next-line quotes
output[outputLength++] = '"';
}
} else {
output[outputLength++] = char;
}
}
// write the actual length and deallocate unused memory
assembly ("memory-safe") {
mstore(output, outputLength)
mstore(0x40, add(output, shl(5, shr(5, add(outputLength, 63)))))
}
return string(output);
}
/**
* @dev Reads a bytes32 from a bytes array without bounds checking.
*
* NOTE: making this function internal would mean it could be used with memory unsafe offset, and marking the
* assembly block as such would prevent some optimizations.
*/
function _unsafeReadBytesOffset(bytes memory buffer, uint256 offset) private pure returns (bytes32 value) {
// This is not memory safe in the general case, but all calls to this private function are within bounds.
assembly ("memory-safe") {
value := mload(add(buffer, add(0x20, offset)))
}
}
}