/** Whether the input is [qdtext](https://www.rfc-editor.org/rfc/rfc9110.html#section-5.6.4-2) or not.
 *
 * @example
 * ```ts
 * import { isQdtext } from "https://deno.land/x/http_utils@$VERSION/quoted_string.ts";
 * import {
 *   assert,
 *   assertFalse,
 * } from "https://deno.land/std@$VERSION/testing/asserts.ts";
 *
 * assert(isQdtext("\t"));
 * assert(isQdtext("\xFF"));
 * assertFalse(isQdtext(`"`));
 * ```
 */
export declare function isQdtext(input: string): boolean;
/** [Quoted pair](https://www.rfc-editor.org/rfc/rfc9110.html#section-5.6.4-4). */
export declare type QuotedPair = `\\${string}`;
/** Whether the input is [quoted-pair](https://www.rfc-editor.org/rfc/rfc9110.html#section-5.6.4-4) or not.
 *
 * @example
 * ```ts
 * import { isQuotedPair } from "https://deno.land/x/http_utils@$VERSION/quoted_string.ts";
 * import {
 *   assert,
 *   assertFalse,
 * } from "https://deno.land/std@$VERSION/testing/asserts.ts";
 *
 * assert(isQuotedPair("\\\t"));
 * assert(isQuotedPair("\\\xFF"));
 * assertFalse(isQuotedPair("\\"));
 * ```
 */
export declare function isQuotedPair(input: string): input is QuotedPair;
/** [quoted-string](https://www.rfc-editor.org/rfc/rfc9110.html#section-5.6.4-2). */
export declare type QuotedString = `"${string}"`;
/** Whether the input is [quoted-string](https://www.rfc-editor.org/rfc/rfc9110.html#section-5.6.4-2) or not.
 *
 * @example
 * ```ts
 * import { isQuotedString } from "https://deno.land/x/http_utils@$VERSION/quoted_string.ts";
 * import {
 *   assert,
 *   assertFalse,
 * } from "https://deno.land/std@$VERSION/testing/asserts.ts";
 *
 * assert(isQuotedString(`""`));
 * assert(isQuotedString(`"qdtext"`));
 * assert(isQuotedString(`"quoted-pair"`));
 * assertFalse(isQuotedString(""));
 * ```
 */
export declare function isQuotedString(input: string): input is QuotedString;