Function buffer

libraries/struct/src/buffer.ts:126–332

(
    lengthOrField:
        | string
        | number
        | Field<number, string, unknown, number>
        | BufferLengthConverter<string, unknown>,
    converter?: Converter<Uint8Array, unknown>,
)

/* #__NO_SIDE_EFFECTS__ */
export function buffer(
    lengthOrField:
        | string
        | number
        | Field<number, string, unknown, number>
        | BufferLengthConverter<string, unknown>,
    converter?: Converter<Uint8Array, unknown>,
): Field<unknown, string, Record<string, unknown>, Uint8Array> {
    // Fixed length
    if (typeof lengthOrField === "number") {
        let serialize: ByobFieldSerializer<Uint8Array>;
        let deserialize: BipedalFieldDeserializer<
            unknown,
            Record<string, unknown>
        >;
        let init: ((value: unknown) => Uint8Array) | undefined;

        if (lengthOrField === 0) {
            serialize = () => {};

            if (converter) {
                // eslint-disable-next-line require-yield
                deserialize = function* () {
                    return converter.convert(EmptyUint8Array);
                };
            } else {
                // eslint-disable-next-line require-yield
                deserialize = function* () {
                    return EmptyUint8Array;
                };
            }
        } else {
            serialize = (value, { buffer, index }) =>
                copyMaybeDifferentLength(buffer, value, index, lengthOrField);

            if (converter) {
                deserialize = function* (then, reader) {
                    const array = reader.readExactly(lengthOrField);
                    return converter.convert(yield* then(array));
                };
                init = (value) => converter.back(value);
            } else {
                // eslint-disable-next-line require-yield
                deserialize = function* (_then, reader) {
                    const array = reader.readExactly(lengthOrField);
                    return array;
                };
            }
        }

        return field(lengthOrField, "byob", serialize, deserialize, { init });
    }

    // Declare length field
    // Some field types are `function`s
    if (
        (typeof lengthOrField === "object" ||
            typeof lengthOrField === "function") &&