// SPDX-License-Identifier: MIT
pragma solidity ^0.8.4;
/// @notice Library for converting numbers into strings and other string operations.
/// @author Solady (https://github.com/vectorized/solady/blob/main/src/utils/LibString.sol)
/// @author Modified from Solmate (https://github.com/transmissions11/solmate/blob/main/src/utils/LibString.sol)
///
/// @dev Note:
/// For performance and bytecode compactness, most of the string operations are restricted to
/// byte strings (7-bit ASCII), except where otherwise specified.
/// Usage of byte string operations on charsets with runes spanning two or more bytes
/// can lead to undefined behavior.
library LibString {
/*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
/* CUSTOM ERRORS */
/*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/
/// @dev The length of the output is too small to contain all the hex digits.
error HexLengthInsufficient();
/// @dev The length of the string is more than 32 bytes.
error TooBigForSmallString();
/// @dev The input string must be a 7-bit ASCII.
error StringNot7BitASCII();
/*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
/* CONSTANTS */
/*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/
/// @dev The constant returned when the `search` is not found in the string.
uint256 internal constant NOT_FOUND = type(uint256).max;
/// @dev Lookup for '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ'.
uint128 internal constant ALPHANUMERIC_7_BIT_ASCII = 0x7fffffe07fffffe03ff000000000000;
/// @dev Lookup for 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ'.
uint128 internal constant LETTERS_7_BIT_ASCII = 0x7fffffe07fffffe0000000000000000;
/// @dev Lookup for 'abcdefghijklmnopqrstuvwxyz'.
uint128 internal constant LOWERCASE_7_BIT_ASCII = 0x7fffffe000000000000000000000000;
/// @dev Lookup for 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'.
uint128 internal constant UPPERCASE_7_BIT_ASCII = 0x7fffffe0000000000000000;
/// @dev Lookup for '0123456789'.
uint128 internal constant DIGITS_7_BIT_ASCII = 0x3ff000000000000;
/// @dev Lookup for '0123456789abcdefABCDEF'.
uint128 internal constant HEXDIGITS_7_BIT_ASCII = 0x7e0000007e03ff000000000000;
/// @dev Lookup for '01234567'.
uint128 internal constant OCTDIGITS_7_BIT_ASCII = 0xff000000000000;
/// @dev Lookup for '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ!"#$%&\'()*+,-./:;<=>?@[\\]^_`{|}~ \t\n\r\x0b\x0c'.
uint128 internal constant PRINTABLE_7_BIT_ASCII = 0x7fffffffffffffffffffffff00003e00;
/// @dev Lookup for '!"#$%&\'()*+,-./:;<=>?@[\\]^_`{|}~'.
uint128 internal constant PUNCTUATION_7_BIT_ASCII = 0x78000001f8000001fc00fffe00000000;
/// @dev Lookup for ' \t\n\r\x0b\x0c'.
uint128 internal constant WHITESPACE_7_BIT_ASCII = 0x100003e00;
/*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
/* DECIMAL OPERATIONS */
/*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/
/// @dev Returns the base 10 decimal representation of `value`.
function toString(uint256 value) internal pure returns (string memory str) {
/// @solidity memory-safe-assembly
assembly {
// The maximum value of a uint256 contains 78 digits (1 byte per digit), but
// we allocate 0xa0 bytes to keep the free memory pointer 32-byte word aligned.
// We will need 1 word for the trailing zeros padding, 1 word for the length,
// and 3 words for a maximum of 78 digits.
str := add(mload(0x40), 0x80)
mstore(0x40, add(str, 0x20)) // Allocate the memory.
mstore(str, 0) // Zeroize the slot after the string.
let end := str // Cache the end of the memory to calculate the length later.
let w := not(0) // Tsk.
// We write the string from rightmost digit to leftmost digit.
// The following is essentially a do-while loop that also handles the zero case.
for { let temp := value } 1 {} {
str := add(str, w) // `sub(str, 1)`.
// Store the character to the pointer.
// The ASCII index of the '0' character is 48.
mstore8(str, add(48, mod(temp, 10)))
temp := div(temp, 10) // Keep dividing `temp` until zero.
if iszero(temp) { break }
}
let length := sub(end, str)
str := sub(str, 0x20) // Move the pointer 32 bytes back to make room for the length.
mstore(str, length) // Store the length.
}
}
/// @dev Returns the base 10 decimal representation of `value`.
function toString(int256 value) internal pure returns (string memory str) {
if (value >= 0) return toString(uint256(value));
unchecked {
str = toString(~uint256(value) + 1);
}
/// @solidity memory-safe-assembly
assembly {
// We still have some spare memory space on the left,
// as we have allocated 3 words (96 bytes) for up to 78 digits.
let length := mload(str) // Load the string length.
mstore(str, 0x2d) // Store the '-' character.
str := sub(str, 1) // Move back the string pointer by a byte.
mstore(str, add(length, 1)) // Update the string length.
}
}
/*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
/* HEXADECIMAL OPERATIONS */
/*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/
/// @dev Returns the hexadecimal representation of `value`,
/// left-padded to an input length of `length` bytes.
/// The output is prefixed with "0x" encoded using 2 hexadecimal digits per byte,
/// giving a total length of `length * 2 + 2` bytes.
/// Reverts if `length` is too small for the output to contain all the digits.
function toHexString(uint256 value, uint256 length) internal pure returns (string memory str) {
str = toHexStringNoPrefix(value, length);
/// @solidity memory-safe-assembly
assembly {
let strLength := add(mload(str), 2) // Compute the length.
mstore(str, 0x3078) // Store the "0x" prefix.
str := sub(str, 2) // Move the pointer.
mstore(str, strLength) // Store the length.
}
}
/// @dev Returns the hexadecimal representation of `value`,
/// left-padded to an input length of `length` bytes.
/// The output is not prefixed with "0x" and is encoded using 2 hexadecimal digits per byte,
/// giving a total length of `length * 2` bytes.
/// Reverts if `length` is too small for the output to contain all the digits.
function toHexStringNoPrefix(uint256 value, uint256 length)
internal
pure
returns (string memory str)
{
/// @solidity memory-safe-assembly
assembly {
// We need 0x20 bytes for the trailing zeros padding, `length * 2` bytes
// for the digits, 0x02 bytes for the prefix, and 0x20 bytes for the length.
// We add 0x20 to the total and round down to a multiple of 0x20.
// (0x20 + 0x20 + 0x02 + 0x20) = 0x62.
str := add(mload(0x40), and(add(shl(1, length), 0x42), not(0x1f)))
mstore(0x40, add(str, 0x20)) // Allocate the memory.
mstore(str, 0) // Zeroize the slot after the string.
let end := str // Cache the end to calculate the length later.
// Store "0123456789abcdef" in scratch space.
mstore(0x0f, 0x30313233343536373839616263646566)
let start := sub(str, add(length, length))
let w := not(1) // Tsk.
let temp := value
// We write the string from rightmost digit to leftmost digit.
// The following is essentially a do-while loop that also handles the zero case.
for {} 1 {} {
str := add(str, w) // `sub(str, 2)`.
mstore8(add(str, 1), mload(and(temp, 15)))
mstore8(str, mload(and(shr(4, temp), 15)))
temp := shr(8, temp)
if iszero(xor(str, start)) { break }
}
if temp {
mstore(0x00, 0x2194895a) // `HexLengthInsufficient()`.
revert(0x1c, 0x04)
}
let strLength := sub(end, str)
str := sub(str, 0x20)
mstore(str, strLength) // Store the length.
}
}
/// @dev Returns the hexadecimal representation of `value`.
/// The output is prefixed with "0x" and encoded using 2 hexadecimal digits per byte.
/// As address are 20 bytes long, the output will left-padded to have
/// a length of `20 * 2 + 2` bytes.
function toHexString(uint256 value) internal pure returns (string memory str) {
str = toHexStringNoPrefix(value);
/// @solidity memory-safe-assembly
assembly {
let strLength := add(mload(str), 2) // Compute the length.
mstore(str, 0x3078) // Store the "0x" prefix.
str := sub(str, 2) // Move the pointer.
mstore(str, strLength) // Store the length.
}
}
/// @dev Returns the hexadecimal representation of `value`.
/// The output is prefixed with "0x".
/// The output excludes leading "0" from the `toHexString` output.
/// `0x00: "0x0", 0x01: "0x1", 0x12: "0x12", 0x123: "0x123"`.
function toMinimalHexString(uint256 value) internal pure returns (string memory str) {
str = toHexStringNoPrefix(value);
/// @solidity memory-safe-assembly
assembly {
let o := eq(byte(0, mload(add(str, 0x20))), 0x30) // Whether leading zero is present.
let strLength := add(mload(str), 2) // Compute the length.
mstore(add(str, o), 0x3078) // Store the "0x" prefix, accounting for leading zero.
str := sub(add(str, o), 2) // Move the pointer, accounting for leading zero.
mstore(str, sub(strLength, o)) // Store the length, accounting for leading zero.
}
}
/// @dev Returns the hexadecimal representation of `value`.
/// The output excludes leading "0" from the `toHexStringNoPrefix` output.
/// `0x00: "0", 0x01: "1", 0x12: "12", 0x123: "123"`.
function toMinimalHexStringNoPrefix(uint256 value) internal pure returns (string memory str) {
str = toHexStringNoPrefix(value);
/// @solidity memory-safe-assembly
assembly {
let o := eq(byte(0, mload(add(str, 0x20))), 0x30) // Whether leading zero is present.
let strLength := mload(str) // Get the length.
str := add(str, o) // Move the pointer, accounting for leading zero.
mstore(str, sub(strLength, o)) // Store the length, accounting for leading zero.
}
}
/// @dev Returns the hexadecimal representation of `value`.
/// The output is encoded using 2 hexadecimal digits per byte.
/// As address are 20 bytes long, the output will left-padded to have
/// a length of `20 * 2` bytes.
function toHexStringNoPrefix(uint256 value) internal pure returns (string memory str) {
/// @solidity memory-safe-assembly
assembly {
// We need 0x20 bytes for the trailing zeros padding, 0x20 bytes for the length,
// 0x02 bytes for the prefix, and 0x40 bytes for the digits.
// The next multiple of 0x20 above (0x20 + 0x20 + 0x02 + 0x40) is 0xa0.
str := add(mload(0x40), 0x80)
mstore(0x40, add(str, 0x20)) // Allocate the memory.
mstore(str, 0) // Zeroize the slot after the string.
let end := str // Cache the end to calculate the length later.
mstore(0x0f, 0x30313233343536373839616263646566) // Store the "0123456789abcdef" lookup.
let w := not(1) // Tsk.
// We write the string from rightmost digit to leftmost digit.
// The following is essentially a do-while loop that also handles the zero case.
for { let temp := value } 1 {} {
str := add(str, w) // `sub(str, 2)`.
mstore8(add(str, 1), mload(and(temp, 15)))
mstore8(str, mload(and(shr(4, temp), 15)))
temp := shr(8, temp)
if iszero(temp) { break }
}
let strLength := sub(end, str)
str := sub(str, 0x20)
mstore(str, strLength) // Store the length.
}
}
/// @dev Returns the hexadecimal representation of `value`.
/// The output is prefixed with "0x", encoded using 2 hexadecimal digits per byte,
/// and the alphabets are capitalized conditionally according to
/// https://eips.ethereum.org/EIPS/eip-55
function toHexStringChecksummed(address value) internal pure returns (string memory str) {
str = toHexString(value);
/// @solidity memory-safe-assembly
assembly {
let mask := shl(6, div(not(0), 255)) // `0b010000000100000000 ...`
let o := add(str, 0x22)
let hashed := and(keccak256(o, 40), mul(34, mask)) // `0b10001000 ... `
let t := shl(240, 136) // `0b10001000 << 240`
for { let i := 0 } 1 {} {
mstore(add(i, i), mul(t, byte(i, hashed)))
i := add(i, 1)
if eq(i, 20) { break }
}
mstore(o, xor(mload(o), shr(1, and(mload(0x00), and(mload(o), mask)))))
o := add(o, 0x20)
mstore(o, xor(mload(o), shr(1, and(mload(0x20), and(mload(o), mask)))))
}
}
/// @dev Returns the hexadecimal representation of `value`.
/// The output is prefixed with "0x" and encoded using 2 hexadecimal digits per byte.
function toHexString(address value) internal pure returns (string memory str) {
str = toHexStringNoPrefix(value);
/// @solidity memory-safe-assembly
assembly {
let strLength := add(mload(str), 2) // Compute the length.
mstore(str, 0x3078) // Store the "0x" prefix.
str := sub(str, 2) // Move the pointer.
mstore(str, strLength) // Store the length.
}
}
/// @dev Returns the hexadecimal representation of `value`.
/// The output is encoded using 2 hexadecimal digits per byte.
function toHexStringNoPrefix(address value) internal pure returns (string memory str) {
/// @solidity memory-safe-assembly
assembly {
str := mload(0x40)
// Allocate the memory.
// We need 0x20 bytes for the trailing zeros padding, 0x20 bytes for the length,
// 0x02 bytes for the prefix, and 0x28 bytes for the digits.
// The next multiple of 0x20 above (0x20 + 0x20 + 0x02 + 0x28) is 0x80.
mstore(0x40, add(str, 0x80))
mstore(0x0f, 0x30313233343536373839616263646566) // Store the "0123456789abcdef" lookup.
str := add(str, 2)
mstore(str, 40) // Store the length.
let o := add(str, 0x20)
mstore(add(o, 40), 0) // Zeroize the slot after the string.
value := shl(96, value)
// We write the string from rightmost digit to leftmost digit.
// The following is essentially a do-while loop that also handles the zero case.
for { let i := 0 } 1 {} {
let p := add(o, add(i, i))
let temp := byte(i, value)
mstore8(add(p, 1), mload(and(temp, 15)))
mstore8(p, mload(shr(4, temp)))
i := add(i, 1)
if eq(i, 20) { break }
}
}
}
/// @dev Returns the hex encoded string from the raw bytes.
/// The output is encoded using 2 hexadecimal digits per byte.
function toHexString(bytes memory raw) internal pure returns (string memory str) {
str = toHexStringNoPrefix(raw);
/// @solidity memory-safe-assembly
assembly {
let strLength := add(mload(str), 2) // Compute the length.
mstore(str, 0x3078) // Store the "0x" prefix.
str := sub(str, 2) // Move the pointer.
mstore(str, strLength) // Store the length.
}
}
/// @dev Returns the hex encoded string from the raw bytes.
/// The output is encoded using 2 hexadecimal digits per byte.
function toHexStringNoPrefix(bytes memory raw) internal pure returns (string memory str) {
/// @solidity memory-safe-assembly
assembly {
let length := mload(raw)
str := add(mload(0x40), 2) // Skip 2 bytes for the optional prefix.
mstore(str, add(length, length)) // Store the length of the output.
mstore(0x0f, 0x30313233343536373839616263646566) // Store the "0123456789abcdef" lookup.
let o := add(str, 0x20)
let end := add(raw, length)
for {} iszero(eq(raw, end)) {} {
raw := add(raw, 1)
mstore8(add(o, 1), mload(and(mload(raw), 15)))
mstore8(o, mload(and(shr(4, mload(raw)), 15)))
o := add(o, 2)
}
mstore(o, 0) // Zeroize the slot after the string.
mstore(0x40, add(o, 0x20)) // Allocate the memory.
}
}
/*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
/* RUNE STRING OPERATIONS */
/*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/
/// @dev Returns the number of UTF characters in the string.
function runeCount(string memory s) internal pure returns (uint256 result) {
/// @solidity memory-safe-assembly
assembly {
if mload(s) {
mstore(0x00, div(not(0), 255))
mstore(0x20, 0x0202020202020202020202020202020202020202020202020303030304040506)
let o := add(s, 0x20)
let end := add(o, mload(s))
for { result := 1 } 1 { result := add(result, 1) } {
o := add(o, byte(0, mload(shr(250, mload(o)))))
if iszero(lt(o, end)) { break }
}
}
}
}
/// @dev Returns if this string is a 7-bit ASCII string.
/// (i.e. all characters codes are in [0..127])
function is7BitASCII(string memory s) internal pure returns (bool result) {
/// @solidity memory-safe-assembly
assembly {
let mask := shl(7, div(not(0), 255))
result := 1
let n := mload(s)
if n {
let o := add(s, 0x20)
let end := add(o, n)
let last := mload(end)
mstore(end, 0)
for {} 1 {} {
if and(mask, mload(o)) {
result := 0
break
}
o := add(o, 0x20)
if iszero(lt(o, end)) { break }
}
mstore(end, last)
}
}
}
/// @dev Returns if this string is a 7-bit ASCII string,
/// AND all characters are in the `allowed` lookup.
/// Note: If `s` is empty, returns true regardless of `allowed`.
function is7BitASCII(string memory s, uint128 allowed) internal pure returns (bool result) {
/// @solidity memory-safe-assembly
assembly {
result := 1
if mload(s) {
let allowed_ := shr(128, shl(128, allowed))
let o := add(s, 0x20)
let end := add(o, mload(s))
for {} 1 {} {
result := and(result, shr(byte(0, mload(o)), allowed_))
o := add(o, 1)
if iszero(and(result, lt(o, end))) { break }
}
}
}
}
/// @dev Converts the bytes in the 7-bit ASCII string `s` to
/// an allowed lookup for use in `is7BitASCII(s, allowed)`.
/// To save runtime gas, you can cache the result in an immutable variable.
function to7BitASCIIAllowedLookup(string memory s) internal pure returns (uint128 result) {
/// @solidity memory-safe-assembly
assembly {
if mload(s) {
let o := add(s, 0x20)
let end := add(o, mload(s))
for {} 1 {} {
result := or(result, shl(byte(0, mload(o)), 1))
o := add(o, 1)
if iszero(lt(o, end)) { break }
}
if shr(128, result) {
mstore(0x00, 0xc9807e0d) // `StringNot7BitASCII()`.
revert(0x1c, 0x04)
}
}
}
}
/*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
/* BYTE STRING OPERATIONS */
/*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/
// For performance and bytecode compactness, byte string operations are restricted
// to 7-bit ASCII strings. All offsets are byte offsets, not UTF character offsets.
// Usage of byte string operations on charsets with runes spanning two or more bytes
// can lead to undefined behavior.
/// @dev Returns `subject` all occurrences of `search` replaced with `replacement`.
function replace(string memory subject, string memory search, string memory replacement)
internal
pure
returns (string memory result)
{
/// @solidity memory-safe-assembly
assembly {
let subjectLength := mload(subject)
let searchLength := mload(search)
let replacementLength := mload(replacement)
subject := add(subject, 0x20)
search := add(search, 0x20)
replacement := add(replacement, 0x20)
result := add(mload(0x40), 0x20)
let subjectEnd := add(subject, subjectLength)
if iszero(gt(searchLength, subjectLength)) {
let subjectSearchEnd := add(sub(subjectEnd, searchLength), 1)
let h := 0
if iszero(lt(searchLength, 0x20)) { h := keccak256(search, searchLength) }
let m := shl(3, sub(0x20, and(searchLength, 0x1f)))
let s := mload(search)
for {} 1 {} {
let t := mload(subject)
// Whether the first `searchLength % 32` bytes of
// `subject` and `search` matches.
if iszero(shr(m, xor(t, s))) {
if h {
if iszero(eq(keccak256(subject, searchLength), h)) {
mstore(result, t)
result := add(result, 1)
subject := add(subject, 1)
if iszero(lt(subject, subjectSearchEnd)) { break }
continue
}
}
// Copy the `replacement` one word at a time.
for { let o := 0 } 1 {} {
mstore(add(result, o), mload(add(replacement, o)))
o := add(o, 0x20)
if iszero(lt(o, replacementLength)) { break }
}
result := add(result, replacementLength)
subject := add(subject, searchLength)
if searchLength {
if iszero(lt(subject, subjectSearchEnd)) { break }
continue
}
}
mstore(result, t)
result := add(result, 1)
subject := add(subject, 1)
if iszero(lt(subject, subjectSearchEnd)) { break }
}
}
let resultRemainder := result
result := add(mload(0x40), 0x20)
let k := add(sub(resultRemainder, result), sub(subjectEnd, subject))
// Copy the rest of the string one word at a time.
for {} lt(subject, subjectEnd) {} {
mstore(resultRemainder, mload(subject))
resultRemainder := add(resultRemainder, 0x20)
subject := add(subject, 0x20)
}
result := sub(result, 0x20)
let last := add(add(result, 0x20), k) // Zeroize the slot after the string.
mstore(last, 0)
mstore(0x40, add(last, 0x20)) // Allocate the memory.
mstore(result, k) // Store the length.
}
}
/// @dev Returns the byte index of the first location of `search` in `subject`,
/// searching from left to right, starting from `from`.
/// Returns `NOT_FOUND` (i.e. `type(uint256).max`) if the `search` is not found.
function indexOf(string memory subject, string memory search, uint256 from)
internal
pure
returns (uint256 result)
{
/// @solidity memory-safe-assembly
assembly {
for { let subjectLength := mload(subject) } 1 {} {
if iszero(mload(search)) {
if iszero(gt(from, subjectLength)) {
result := from
break
}
result := subjectLength
break
}
let searchLength := mload(search)
let subjectStart := add(subject, 0x20)
result := not(0) // Initialize to `NOT_FOUND`.
subject := add(subjectStart, from)
let end := add(sub(add(subjectStart, subjectLength), searchLength), 1)
let m := shl(3, sub(0x20, and(searchLength, 0x1f)))
let s := mload(add(search, 0x20))
if iszero(and(lt(subject, end), lt(from, subjectLength))) { break }
if iszero(lt(searchLength, 0x20)) {
for { let h := keccak256(add(search, 0x20), searchLength) } 1 {} {
if iszero(shr(m, xor(mload(subject), s))) {
if eq(keccak256(subject, searchLength), h) {
result := sub(subject, subjectStart)
break
}
}
subject := add(subject, 1)
if iszero(lt(subject, end)) { break }
}
break
}
for {} 1 {} {
if iszero(shr(m, xor(mload(subject), s))) {
result := sub(subject, subjectStart)
break
}
subject := add(subject, 1)
if iszero(lt(subject, end)) { break }
}
break
}
}
}
/// @dev Returns the byte index of the first location of `search` in `subject`,
/// searching from left to right.
/// Returns `NOT_FOUND` (i.e. `type(uint256).max`) if the `search` is not found.
function indexOf(string memory subject, string memory search)
internal
pure
returns (uint256 result)
{
result = indexOf(subject, search, 0);
}
/// @dev Returns the byte index of the first location of `search` in `subject`,
/// searching from right to left, starting from `from`.
/// Returns `NOT_FOUND` (i.e. `type(uint256).max`) if the `search` is not found.
function lastIndexOf(string memory subject, string memory search, uint256 from)
internal
pure
returns (uint256 result)
{
/// @solidity memory-safe-assembly
assembly {
for {} 1 {} {
result := not(0) // Initialize to `NOT_FOUND`.
let searchLength := mload(search)
if gt(searchLength, mload(subject)) { break }
let w := result
let fromMax := sub(mload(subject), searchLength)
if iszero(gt(fromMax, from)) { from := fromMax }
let end := add(add(subject, 0x20), w)
subject := add(add(subject, 0x20), from)
if iszero(gt(subject, end)) { break }
// As this function is not too often used,
// we shall simply use keccak256 for smaller bytecode size.
for { let h := keccak256(add(search, 0x20), searchLength) } 1 {} {
if eq(keccak256(subject, searchLength), h) {
result := sub(subject, add(end, 1))
break
}
subject := add(subject, w) // `sub(subject, 1)`.
if iszero(gt(subject, end)) { break }
}
break
}
}
}
/// @dev Returns the byte index of the first location of `search` in `subject`,
/// searching from right to left.
/// Returns `NOT_FOUND` (i.e. `type(uint256).max`) if the `search` is not found.
function lastIndexOf(string memory subject, string memory search)
internal
pure
returns (uint256 result)
{
result = lastIndexOf(subject, search, uint256(int256(-1)));
}
/// @dev Returns true if `search` is found in `subject`, false otherwise.
function contains(string memory subject, string memory search) internal pure returns (bool) {
return indexOf(subject, search) != NOT_FOUND;
}
/// @dev Returns whether `subject` starts with `search`.
function startsWith(string memory subject, string memory search)
internal
pure
returns (bool result)
{
/// @solidity memory-safe-assembly
assembly {
let searchLength := mload(search)
// Just using keccak256 directly is actually cheaper.
// forgefmt: disable-next-item
result := and(
iszero(gt(searchLength, mload(subject))),
eq(
keccak256(add(subject, 0x20), searchLength),
keccak256(add(search, 0x20), searchLength)
)
)
}
}
/// @dev Returns whether `subject` ends with `search`.
function endsWith(string memory subject, string memory search)
internal
pure
returns (bool result)
{
/// @solidity memory-safe-assembly
assembly {
let searchLength := mload(search)
let subjectLength := mload(subject)
// Whether `search` is not longer than `subject`.
let withinRange := iszero(gt(searchLength, subjectLength))
// Just using keccak256 directly is actually cheaper.
// forgefmt: disable-next-item
result := and(
withinRange,
eq(
keccak256(
// `subject + 0x20 + max(subjectLength - searchLength, 0)`.
add(add(subject, 0x20), mul(withinRange, sub(subjectLength, searchLength))),
searchLength
),
keccak256(add(search, 0x20), searchLength)
)
)
}
}
/// @dev Returns `subject` repeated `times`.
function repeat(string memory subject, uint256 times)
internal
pure
returns (string memory result)
{
/// @solidity memory-safe-assembly
assembly {
let subjectLength := mload(subject)
if iszero(or(iszero(times), iszero(subjectLength))) {
subject := add(subject, 0x20)
result := mload(0x40)
let output := add(result, 0x20)
for {} 1 {} {
// Copy the `subject` one word at a time.
for { let o := 0 } 1 {} {
mstore(add(output, o), mload(add(subject, o)))
o := add(o, 0x20)
if iszero(lt(o, subjectLength)) { break }
}
output := add(output, subjectLength)
times := sub(times, 1)
if iszero(times) { break }
}
mstore(output, 0) // Zeroize the slot after the string.
let resultLength := sub(output, add(result, 0x20))
mstore(result, resultLength) // Store the length.
mstore(0x40, add(result, add(resultLength, 0x40))) // Allocate the memory.
}
}
}
/// @dev Returns a copy of `subject` sliced from `start` to `end` (exclusive).
/// `start` and `end` are byte offsets.
function slice(string memory subject, uint256 start, uint256 end)
internal
pure
returns (string memory result)
{
/// @solidity memory-safe-assembly
assembly {
let subjectLength := mload(subject)
if iszero(gt(subjectLength, end)) { end := subjectLength }
if iszero(gt(subjectLength, start)) { start := subjectLength }
if lt(start, end) {
result := mload(0x40)
let resultLength := sub(end, start)
mstore(result, resultLength)
subject := add(subject, start)
let w := not(0x1f)
// Copy the `subject` one word at a time, backwards.
for { let o := and(add(resultLength, 0x1f), w) } 1 {} {
mstore(add(result, o), mload(add(subject, o)))
o := add(o, w) // `sub(o, 0x20)`.
if iszero(o) { break }
}
// Zeroize the slot after the string.
mstore(add(add(result, 0x20), resultLength), 0)
mstore(0x40, add(result, add(resultLength, 0x40))) // Allocate the memory.
}
}
}
/// @dev Returns a copy of `subject` sliced from `start` to the end of the string.
/// `start` is a byte offset.
function slice(string memory subject, uint256 start)
internal
pure
returns (string memory result)
{
result = slice(subject, start, uint256(int256(-1)));
}
/// @dev Returns all the indices of `search` in `subject`.
/// The indices are byte offsets.
function indicesOf(string memory subject, string memory search)
internal
pure
returns (uint256[] memory result)
{
/// @solidity memory-safe-assembly
assembly {
let subjectLength := mload(subject)
let searchLength := mload(search)
if iszero(gt(searchLength, subjectLength)) {
subject := add(subject, 0x20)
search := add(search, 0x20)
result := add(mload(0x40), 0x20)
let subjectStart := subject
let subjectSearchEnd := add(sub(add(subject, subjectLength), searchLength), 1)
let h := 0
if iszero(lt(searchLength, 0x20)) { h := keccak256(search, searchLength) }
let m := shl(3, sub(0x20, and(searchLength, 0x1f)))
let s := mload(search)
for {} 1 {} {
let t := mload(subject)
// Whether the first `searchLength % 32` bytes of
// `subject` and `search` matches.
if iszero(shr(m, xor(t, s))) {
if h {
if iszero(eq(keccak256(subject, searchLength), h)) {
subject := add(subject, 1)
if iszero(lt(subject, subjectSearchEnd)) { break }
continue
}
}
// Append to `result`.
mstore(result, sub(subject, subjectStart))
result := add(result, 0x20)
// Advance `subject` by `searchLength`.
subject := add(subject, searchLength)
if searchLength {
if iszero(lt(subject, subjectSearchEnd)) { break }
continue
}
}
subject := add(subject, 1)
if iszero(lt(subject, subjectSearchEnd)) { break }
}
let resultEnd := result
// Assign `result` to the free memory pointer.
result := mload(0x40)
// Store the length of `result`.
mstore(result, shr(5, sub(resultEnd, add(result, 0x20))))
// Allocate memory for result.
// We allocate one more word, so this array can be recycled for {split}.
mstore(0x40, add(resultEnd, 0x20))
}
}
}
/// @dev Returns a arrays of strings based on the `delimiter` inside of the `subject` string.
function split(string memory subject, string memory delimiter)
internal
pure
returns (string[] memory result)
{
uint256[] memory indices = indicesOf(subject, delimiter);
/// @solidity memory-safe-assembly
assembly {
let w := not(0x1f)
let indexPtr := add(indices, 0x20)
let indicesEnd := add(indexPtr, shl(5, add(mload(indices), 1)))
mstore(add(indicesEnd, w), mload(subject))
mstore(indices, add(mload(indices), 1))
let prevIndex := 0
for {} 1 {} {
let index := mload(indexPtr)
mstore(indexPtr, 0x60)
if iszero(eq(index, prevIndex)) {
let element := mload(0x40)
let elementLength := sub(index, prevIndex)
mstore(element, elementLength)
// Copy the `subject` one word at a time, backwards.
for { let o := and(add(elementLength, 0x1f), w) } 1 {} {
mstore(add(element, o), mload(add(add(subject, prevIndex), o)))
o := add(o, w) // `sub(o, 0x20)`.
if iszero(o) { break }
}
// Zeroize the slot after the string.
mstore(add(add(element, 0x20), elementLength), 0)
// Allocate memory for the length and the bytes,
// rounded up to a multiple of 32.
mstore(0x40, add(element, and(add(elementLength, 0x3f), w)))
// Store the `element` into the array.
mstore(indexPtr, element)
}
prevIndex := add(index, mload(delimiter))
indexPtr := add(indexPtr, 0x20)
if iszero(lt(indexPtr, indicesEnd)) { break }
}
result := indices
if iszero(mload(delimiter)) {
result := add(indices, 0x20)
mstore(result, sub(mload(indices), 2))
}
}
}
/// @dev Returns a concatenated string of `a` and `b`.
/// Cheaper than `string.concat()` and does not de-align the free memory pointer.
function concat(string memory a, string memory b)
internal
pure
returns (string memory result)
{
/// @solidity memory-safe-assembly
assembly {
let w := not(0x1f)
result := mload(0x40)
let aLength := mload(a)
// Copy `a` one word at a time, backwards.
for { let o := and(add(aLength, 0x20), w) } 1 {} {
mstore(add(result, o), mload(add(a, o)))
o := add(o, w) // `sub(o, 0x20)`.
if iszero(o) { break }
}
let bLength := mload(b)
let output := add(result, aLength)
// Copy `b` one word at a time, backwards.
for { let o := and(add(bLength, 0x20), w) } 1 {} {
mstore(add(output, o), mload(add(b, o)))
o := add(o, w) // `sub(o, 0x20)`.
if iszero(o) { break }
}
let totalLength := add(aLength, bLength)
let last := add(add(result, 0x20), totalLength)
mstore(last, 0) // Zeroize the slot after the string.
mstore(result, totalLength) // Store the length.
mstore(0x40, add(last, 0x20)) // Allocate the memory.
}
}
/// @dev Returns a copy of the string in either lowercase or UPPERCASE.
/// WARNING! This function is only compatible with 7-bit ASCII strings.
function toCase(string memory subject, bool toUpper)
internal
pure
returns (string memory result)
{
/// @solidity memory-safe-assembly
assembly {
let length := mload(subject)
if length {
result := add(mload(0x40), 0x20)
subject := add(subject, 1)
let flags := shl(add(70, shl(5, toUpper)), 0x3ffffff)
let w := not(0)
for { let o := length } 1 {} {
o := add(o, w)
let b := and(0xff, mload(add(subject, o)))
mstore8(add(result, o), xor(b, and(shr(b, flags), 0x20)))
if iszero(o) { break }
}
result := mload(0x40)
mstore(result, length) // Store the length.
let last := add(add(result, 0x20), length)
mstore(last, 0) // Zeroize the slot after the string.
mstore(0x40, add(last, 0x20)) // Allocate the memory.
}
}
}
/// @dev Returns a string from a small bytes32 string.
/// `s` must be null-terminated, or behavior will be undefined.
function fromSmallString(bytes32 s) internal pure returns (string memory result) {
/// @solidity memory-safe-assembly
assembly {
result := mload(0x40)
let n := 0
for {} byte(n, s) { n := add(n, 1) } {} // Scan for '\0'.
mstore(result, n) // Store the length.
let o := add(result, 0x20)
mstore(o, s) // Store the bytes of the string.
mstore(add(o, n), 0) // Zeroize the slot after the string.
mstore(0x40, add(result, 0x40)) // Allocate the memory.
}
}
/// @dev Returns the small string, with all bytes after the first null byte zeroized.
function normalizeSmallString(bytes32 s) internal pure returns (bytes32 result) {
/// @solidity memory-safe-assembly
assembly {
for {} byte(result, s) { result := add(result, 1) } {} // Scan for '\0'.
mstore(0x00, s)
mstore(result, 0x00)
result := mload(0x00)
}
}
/// @dev Returns the string as a normalized null-terminated small string.
function toSmallString(string memory s) internal pure returns (bytes32 result) {
/// @solidity memory-safe-assembly
assembly {
result := mload(s)
if iszero(lt(result, 33)) {
mstore(0x00, 0xec92f9a3) // `TooBigForSmallString()`.
revert(0x1c, 0x04)
}
result := shl(shl(3, sub(32, result)), mload(add(s, result)))
}
}
/// @dev Returns a lowercased copy of the string.
/// WARNING! This function is only compatible with 7-bit ASCII strings.
function lower(string memory subject) internal pure returns (string memory result) {
result = toCase(subject, false);
}
/// @dev Returns an UPPERCASED copy of the string.
/// WARNING! This function is only compatible with 7-bit ASCII strings.
function upper(string memory subject) internal pure returns (string memory result) {
result = toCase(subject, true);
}
/// @dev Escapes the string to be used within HTML tags.
function escapeHTML(string memory s) internal pure returns (string memory result) {
/// @solidity memory-safe-assembly
assembly {
let end := add(s, mload(s))
result := add(mload(0x40), 0x20)
// Store the bytes of the packed offsets and strides into the scratch space.
// `packed = (stride << 5) | offset`. Max offset is 20. Max stride is 6.
mstore(0x1f, 0x900094)
mstore(0x08, 0xc0000000a6ab)
// Store ""&'<>" into the scratch space.
mstore(0x00, shl(64, 0x2671756f743b26616d703b262333393b266c743b2667743b))
for {} iszero(eq(s, end)) {} {
s := add(s, 1)
let c := and(mload(s), 0xff)
// Not in `["\"","'","&","<",">"]`.
if iszero(and(shl(c, 1), 0x500000c400000000)) {
mstore8(result, c)
result := add(result, 1)
continue
}
let t := shr(248, mload(c))
mstore(result, mload(and(t, 0x1f)))
result := add(result, shr(5, t))
}
let last := result
mstore(last, 0) // Zeroize the slot after the string.
result := mload(0x40)
mstore(result, sub(last, add(result, 0x20))) // Store the length.
mstore(0x40, add(last, 0x20)) // Allocate the memory.
}
}
/// @dev Escapes the string to be used within double-quotes in a JSON.
/// If `addDoubleQuotes` is true, the result will be enclosed in double-quotes.
function escapeJSON(string memory s, bool addDoubleQuotes)
internal
pure
returns (string memory result)
{
/// @solidity memory-safe-assembly
assembly {
let end := add(s, mload(s))
result := add(mload(0x40), 0x20)
if addDoubleQuotes {
mstore8(result, 34)
result := add(1, result)
}
// Store "\\u0000" in scratch space.
// Store "0123456789abcdef" in scratch space.
// Also, store `{0x08:"b", 0x09:"t", 0x0a:"n", 0x0c:"f", 0x0d:"r"}`.
// into the scratch space.
mstore(0x15, 0x5c75303030303031323334353637383961626364656662746e006672)
// Bitmask for detecting `["\"","\\"]`.
let e := or(shl(0x22, 1), shl(0x5c, 1))
for {} iszero(eq(s, end)) {} {
s := add(s, 1)
let c := and(mload(s), 0xff)
if iszero(lt(c, 0x20)) {
if iszero(and(shl(c, 1), e)) {
// Not in `["\"","\\"]`.
mstore8(result, c)
result := add(result, 1)
continue
}
mstore8(result, 0x5c) // "\\".
mstore8(add(result, 1), c)
result := add(result, 2)
continue
}
if iszero(and(shl(c, 1), 0x3700)) {
// Not in `["\b","\t","\n","\f","\d"]`.
mstore8(0x1d, mload(shr(4, c))) // Hex value.
mstore8(0x1e, mload(and(c, 15))) // Hex value.
mstore(result, mload(0x19)) // "\\u00XX".
result := add(result, 6)
continue
}
mstore8(result, 0x5c) // "\\".
mstore8(add(result, 1), mload(add(c, 8)))
result := add(result, 2)
}
if addDoubleQuotes {
mstore8(result, 34)
result := add(1, result)
}
let last := result
mstore(last, 0) // Zeroize the slot after the string.
result := mload(0x40)
mstore(result, sub(last, add(result, 0x20))) // Store the length.
mstore(0x40, add(last, 0x20)) // Allocate the memory.
}
}
/// @dev Escapes the string to be used within double-quotes in a JSON.
function escapeJSON(string memory s) internal pure returns (string memory result) {
result = escapeJSON(s, false);
}
/// @dev Returns whether `a` equals `b`.
function eq(string memory a, string memory b) internal pure returns (bool result) {
/// @solidity memory-safe-assembly
assembly {
result := eq(keccak256(add(a, 0x20), mload(a)), keccak256(add(b, 0x20), mload(b)))
}
}
/// @dev Returns whether `a` equals `b`, where `b` is a null-terminated small string.
function eqs(string memory a, bytes32 b) internal pure returns (bool result) {
/// @solidity memory-safe-assembly
assembly {
// These should be evaluated on compile time, as far as possible.
let m := not(shl(7, div(not(iszero(b)), 255))) // `0x7f7f ...`.
let x := not(or(m, or(b, add(m, and(b, m)))))
let r := shl(7, iszero(iszero(shr(128, x))))
r := or(r, shl(6, iszero(iszero(shr(64, shr(r, x))))))
r := or(r, shl(5, lt(0xffffffff, shr(r, x))))
r := or(r, shl(4, lt(0xffff, shr(r, x))))
r := or(r, shl(3, lt(0xff, shr(r, x))))
// forgefmt: disable-next-item
result := gt(eq(mload(a), add(iszero(x), xor(31, shr(3, r)))),
xor(shr(add(8, r), b), shr(add(8, r), mload(add(a, 0x20)))))
}
}
/// @dev Packs a single string with its length into a single word.
/// Returns `bytes32(0)` if the length is zero or greater than 31.
function packOne(string memory a) internal pure returns (bytes32 result) {
/// @solidity memory-safe-assembly
assembly {
// We don't need to zero right pad the string,
// since this is our own custom non-standard packing scheme.
result :=
mul(
// Load the length and the bytes.
mload(add(a, 0x1f)),
// `length != 0 && length < 32`. Abuses underflow.
// Assumes that the length is valid and within the block gas limit.
lt(sub(mload(a), 1), 0x1f)
)
}
}
/// @dev Unpacks a string packed using {packOne}.
/// Returns the empty string if `packed` is `bytes32(0)`.
/// If `packed` is not an output of {packOne}, the output behavior is undefined.
function unpackOne(bytes32 packed) internal pure returns (string memory result) {
/// @solidity memory-safe-assembly
assembly {
result := mload(0x40) // Grab the free memory pointer.
mstore(0x40, add(result, 0x40)) // Allocate 2 words (1 for the length, 1 for the bytes).
mstore(result, 0) // Zeroize the length slot.
mstore(add(result, 0x1f), packed) // Store the length and bytes.
mstore(add(add(result, 0x20), mload(result)), 0) // Right pad with zeroes.
}
}
/// @dev Packs two strings with their lengths into a single word.
/// Returns `bytes32(0)` if combined length is zero or greater than 30.
function packTwo(string memory a, string memory b) internal pure returns (bytes32 result) {
/// @solidity memory-safe-assembly
assembly {
let aLength := mload(a)
// We don't need to zero right pad the strings,
// since this is our own custom non-standard packing scheme.
result :=
mul(
or( // Load the length and the bytes of `a` and `b`.
shl(shl(3, sub(0x1f, aLength)), mload(add(a, aLength))),
mload(sub(add(b, 0x1e), aLength))
),
// `totalLength != 0 && totalLength < 31`. Abuses underflow.
// Assumes that the lengths are valid and within the block gas limit.
lt(sub(add(aLength, mload(b)), 1), 0x1e)
)
}
}
/// @dev Unpacks strings packed using {packTwo}.
/// Returns the empty strings if `packed` is `bytes32(0)`.
/// If `packed` is not an output of {packTwo}, the output behavior is undefined.
function unpackTwo(bytes32 packed)
internal
pure
returns (string memory resultA, string memory resultB)
{
/// @solidity memory-safe-assembly
assembly {
resultA := mload(0x40) // Grab the free memory pointer.
resultB := add(resultA, 0x40)
// Allocate 2 words for each string (1 for the length, 1 for the byte). Total 4 words.
mstore(0x40, add(resultB, 0x40))
// Zeroize the length slots.
mstore(resultA, 0)
mstore(resultB, 0)
// Store the lengths and bytes.
mstore(add(resultA, 0x1f), packed)
mstore(add(resultB, 0x1f), mload(add(add(resultA, 0x20), mload(resultA))))
// Right pad with zeroes.
mstore(add(add(resultA, 0x20), mload(resultA)), 0)
mstore(add(add(resultB, 0x20), mload(resultB)), 0)
}
}
/// @dev Directly returns `a` without copying.
function directReturn(string memory a) internal pure {
assembly {
// Assumes that the string does not start from the scratch space.
let retStart := sub(a, 0x20)
let retUnpaddedSize := add(mload(a), 0x40)
// Right pad with zeroes. Just in case the string is produced
// by a method that doesn't zero right pad.
mstore(add(retStart, retUnpaddedSize), 0)
mstore(retStart, 0x20) // Store the return offset.
// End the transaction, returning the string.
return(retStart, and(not(0x1f), add(0x1f, retUnpaddedSize)))
}
}
}