/**
 * Compare two byte arrays for equality
 */
export declare function bytesEqual(left: Uint8Array, right: Uint8Array): boolean;
/**
 * Find index of one byte array in another
 */
export declare function indexOf(haystack: Uint8Array, needle: Uint8Array): number;
/**
 * Split a stream of bytes
 *
 * Takes a stream of data modeled as an async iterator of ArrayBuffer for
 * compatibility between node and web, and splits it into an async iterator
 * where each value is delimited by the split sequence.
 */
export declare function splitStream(iter: AsyncIterable<Uint8Array>, split: Uint8Array): AsyncIterableIterator<Uint8Array>;
/**
 * collect an async iterable of buffers into one
 */
export declare function collect(stream: AsyncIterable<Uint8Array>): Promise<Uint8Array>;
/** whether a character code is a hex digit (0-9, A-F, a-f) */
export declare function isHexDigit(code: number): boolean;
/**
 * decoder for quoted printable
 *
 * If quoted printable "lines" aren't escaped with an "=" then a new line needs
 * to be inserted. We use `newLine`, which defaults to CRLF to match the
 * canonical MIME form; pass a custom separator (e.g. a single "\n") to
 * normalize instead. The separator goes between lines; the CRLF before the MIME
 * boundary belongs to the delimiter, not the body.
 */
export declare function decodeQuotedPrintable(lines: AsyncIterable<Uint8Array>, newLine?: Uint8Array): AsyncIterableIterator<Uint8Array>;
/**
 * decoder for base64
 *
 * RFC 2045 requires decoders to ignore line breaks and decode the concatenated
 * stream, so producers may wrap at any column. We strip whitespace and buffer
 * characters that don't yet form a complete four-character quantum, flushing
 * the remainder at the end of the part.
 */
export declare function decodeBase64(lines: AsyncIterable<Uint8Array>): AsyncIterableIterator<Uint8Array>;
/**
 * decoder for 7bit and 8bit
 *
 * 7bit/8bit apply no transfer transformation, so the content bytes are the
 * payload as-is. parseMhtml splits the stream on CRLF to find part boundaries,
 * so we re-insert `newLine` (defaulting to CRLF) between lines to restore the
 * original bytes exactly. Pass `newLine` (e.g. a single "\n") to normalize line
 * endings instead. The separator goes between lines; the CRLF before the
 * boundary belongs to the delimiter, not the body.
 */
export declare function decodeIdentity(lines: AsyncIterable<Uint8Array>, newLine?: Uint8Array): AsyncIterableIterator<Uint8Array>;
/**
 * decoder for binary
 *
 * For implementation reasons, binary can't be supported, so we throw a special
 * error.
 */
export declare function decodeBinary(): never;