typia/src/functional/$zigzag.ts

Superfast runtime validators with only one line

export function $zigzag_encode(value: number): number;
export function $zigzag_encode(value: bigint): bigint;
export function $zigzag_encode(value: number | bigint): any {
  // TODO: optimize (branchless solution exists)

  if (typeof value === "bigint") {
    if (value < BigInt(0)) {
      value = -value;
      return value * BigInt(2) - BigInt(1);
    }
    return value * BigInt(2);
  }

  if (value < 0) {
    value = -value;
    return value * 2 - 1;
  }
  return value * 2;
}

export function $zigzag_decode(value: number): number;
export function $zigzag_decode(value: bigint): bigint;
export function $zigzag_decode(value: number | bigint): any {
  // TODO: optimize (branchless solution exists)

  if (typeof value === "bigint") {
    value = BigInt.asUintN(64, value);
    if (value & BigInt(1)) {
      return -(value + BigInt(1)) / BigInt(2);
    }
    return value / BigInt(2);
  }

  value = value >>> 0;
  if (value & 1) {
    return -(value + 1) / 2;
  }
  return value / 2;
}