Function decodeMap

cbor/_common_decode.ts:348–393

(
  input: Uint8Array,
  offset: number,
)

}

function decodeMap(
  input: Uint8Array,
  offset: number,
): [Map<CborType, CborType>, number] {
  const byte = input[offset++];
  if (byte == undefined) throw new RangeError("More bytes were expected");
  if (byte >> 5 !== 5) throw new TypeError('Invalid TagItem: Expected a "map"');
  const aI = byte & 0b000_11111;
  if (aI <= 27) {
    const x = calcLength(input, aI, offset);
    // Can safely assume `x[0] < 2 ** 53` as JavaScript doesn't support an `Map` being that large.
    const length = Number(x[0]);
    offset = x[1];
    const output = new Map<CborType, CborType>();
    for (let i = 0; i < length; ++i) {
      const y = decode(input, offset);
      if (output.has(y[0])) {
        throw new TypeError(
          `A Map cannot have duplicate keys: Key (${y[0]}) already exists`,
        ); // https://datatracker.ietf.org/doc/html/rfc8949#name-specifying-keys-for-maps
      }
      const z = decode(input, y[1]);
      output.set(y[0], z[0]);
      offset = z[1];
    }
    return [output, offset];
  }
  if (aI === 31) {
    const output = new Map<CborType, CborType>();
    while (input[offset] !== 0b111_11111) {
      const x = decode(input, offset);
      if (output.has(x[0])) {
        throw new TypeError(
          `A Map cannot have duplicate keys: Key (${x[0]}) already exists`,
        ); // https://datatracker.ietf.org/doc/html/rfc8949#name-specifying-keys-for-maps
      }
      const y = decode(input, x[1]);
      output.set(x[0], y[0]);
      offset = y[1];
    }
    return [output, offset + 1];
  }
  throw new RangeError(
    `Cannot decode value (0b101_${aI.toString(2).padStart(5, "0")})`,
  );
}