/** True when a user range forces the wide class. */
export declare const userWide: (code: number) => boolean;
/** True when a user range forces the composing class. */
export declare const userComposing: (code: number) => boolean;
export declare function initCharset(): void;
/** True for a character less omits from the display, like is_omit_char. */
export declare function omitChar(code: number): boolean;
/** True for a binary byte in the current charset, like binary_char. */
export declare const binaryByte: (byte: number) => boolean;
/** True for a control byte, like control_char. */
export declare const controlByte: (byte: number) => boolean;
/**
 * True for a Unicode char displayed as binary, like is_ubin_char:
 * unassigned, surrogate, private-use and raw control planes.
 */
export declare function ubinChar(char: string): boolean;
/**
 * Renders a binary byte with $LESSBINFMT and the binary attribute,
 * like line.c drawing with binattr (the BIN color under -D).
 */
export declare function binByteText(byte: number): string;
/** Renders a binary Unicode char with $LESSUTFBINFMT. */
export declare function utfBinText(code: number): string;
/** The raw byte carried by a private-use marker, or -1. */
export declare function rawByteOf(char: string): number;
/**
 * Decodes file bytes for display, like less reading through the
 * charset: valid UTF-8 sequences become chars and invalid bytes
 * become private-use markers later rendered with $LESSBINFMT; other
 * charsets map bytes through latin1 with their chardef classes.
 */
export declare function decodeContent(data: Buffer): string;
/**
 * Incrementally decodes pipe bytes into complete lines, like less's ch
 * layer reading a non-seekable input: a multibyte sequence split
 * across chunks is held back rather than decoded as binary markers,
 * and the trailing partial line waits for its newline (or the end of
 * the input).
 */
export declare class PipeDecoder {
    private bytes;
    private tail;
    /** Decodes one chunk and returns the complete lines in it. */
    push(chunk: Buffer): string[];
    /** The final partial line once the input ends, if any. */
    flush(): string[];
}