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/* Imports: External */
import { BigNumber, ethers } from 'ethers'
import { hexZeroPad } from '@ethersproject/bytes'
/**
* Removes "0x" from start of a string if it exists.
*
* @param str String to modify.
* @returns the string without "0x".
*/
export const remove0x = (str: string): string => {
if (str === undefined) {
return str
}
return str.startsWith('0x') ? str.slice(2) : str
}
/**
* Adds "0x" to the start of a string if necessary.
*
* @param str String to modify.
* @returns the string with "0x".
*/
export const add0x = (str: string): string => {
if (str === undefined) {
return str
}
return str.startsWith('0x') ? str : '0x' + str
}
/**
* Casts a hex string to a buffer.
*
* @param inp Input to cast to a buffer.
* @return Input cast as a buffer.
*/
export const fromHexString = (inp: Buffer | string): Buffer => {
if (typeof inp === 'string' && inp.startsWith('0x')) {
return Buffer.from(inp.slice(2), 'hex')
}
return Buffer.from(inp)
}
/**
* Casts an input to a hex string.
*
* @param inp Input to cast to a hex string.
* @return Input cast as a hex string.
*/
export const toHexString = (inp: Buffer | string | number | null): string => {
if (typeof inp === 'number') {
return BigNumber.from(inp).toHexString()
} else {
return '0x' + fromHexString(inp).toString('hex')
}
}
/**
* Casts a number to a hex string without zero padding.
*
* @param n Number to cast to a hex string.
* @return Number cast as a hex string.
*/
export const toRpcHexString = (n: number | BigNumber): string => {
let num
if (typeof n === 'number') {
num = '0x' + n.toString(16)
} else {
num = n.toHexString()
}
if (num === '0x0') {
return num
} else {
// BigNumber pads a single 0 to keep hex length even
return num.replace(/^0x0/, '0x')
}
}
/**
* Zero pads a hex string if str.length !== 2 + length * 2. Pads to length * 2.
*
* @param str Hex string to pad
* @param length Half the length of the desired padded hex string
* @return Hex string with length of 2 + length * 2
*/
export const padHexString = (str: string, length: number): string => {
if (str.length === 2 + length * 2) {
return str
} else {
return '0x' + str.slice(2).padStart(length * 2, '0')
}
}
/**
* Casts an input to hex string without '0x' prefix with conditional padding.
* Hex string will always start with a 0.
*
* @param val Input to cast to a hex string.
* @param len Desired length to pad hex string. Ignored if less than hex string length.
* @return Hex string with '0' prefix
*/
export const encodeHex = (val: any, len: number): string =>
remove0x(BigNumber.from(val).toHexString()).padStart(len, '0')
/**
* Case insensitive hex string equality check
*
* @param stringA Hex string A
* @param stringB Hex string B
* @throws {Error} Inputs must be valid hex strings
* @return True if equal
*/
export const hexStringEquals = (stringA: string, stringB: string): boolean => {
if (!ethers.utils.isHexString(stringA)) {
throw new Error(`input is not a hex string: ${stringA}`)
}
if (!ethers.utils.isHexString(stringB)) {
throw new Error(`input is not a hex string: ${stringB}`)
}
return stringA.toLowerCase() === stringB.toLowerCase()
}
/**
* Casts a number to a 32-byte, zero padded hex string.
*
* @param value Number to cast to a hex string.
* @return Number cast as a hex string.
*/
export const bytes32ify = (value: number | BigNumber): string => {
return hexZeroPad(BigNumber.from(value).toHexString(), 32)
}