@dfinity/candid/src/utils/hash.ts

JavaScript and TypeScript library to work with candid interfaces

/**
 * Hashes a string to a number. Algorithm can be found here:
 * https://caml.inria.fr/pub/papers/garrigue-polymorphic_variants-ml98.pdf
 * @param s - string to hash
 * @returns number representing hashed string
 */
function idlHash(s: string): number {
  const utf8encoder = new TextEncoder();
  const array = utf8encoder.encode(s);

  let h = 0;
  for (const c of array) {
    h = (h * 223 + c) % 2 ** 32;
  }
  return h;
}

/**
 *
 * @param label string
 * @returns number representing hashed label
 */
export function idlLabelToId(label: string): number {
  if (/^_\d+_$/.test(label) || /^_0x[0-9a-fA-F]+_$/.test(label)) {
    const num = +label.slice(1, -1);
    if (Number.isSafeInteger(num) && num >= 0 && num < 2 ** 32) {
      return num;
    }
  }
  return idlHash(label);
}