/**
 * Walking markdown code fences, blockquotes included.
 *
 * Three places need to know whether a line sits inside a fence: the scanner
 * (so a `[/DOC]` shown in a fence isn't mistaken for the real closer), the
 * island splitter, and the projection's mask (so `{ a: 1 }` in a fence isn't
 * compiled as a Svelte expression). They agreed on everything except that a
 * fence can also open inside a blockquote — CommonMark allows it, and a
 * GitHub-style callout is the common case:
 *
 *     > [!IMPORTANT]
 *     > ```js
 *     > export default { outDir: 'docs-dist' };
 *     > ```
 *
 * Read as prose, that middle line hands Svelte an object literal and the page
 * fails to compile. One stepper, used by all three, keeps them from drifting.
 */
/** An open fence: its marker char, its length, and whether it opened inside a
 * blockquote. Null when no fence is open. */
export type FenceState = {
    marker: string;
    len: number;
    inQuote: boolean;
} | null;
/**
 * Advance `state` by one line.
 *
 * `fence` marks the opener/closer lines themselves; `inside` marks lines the
 * fence covers, openers and closers included. A caller that treats code as
 * opaque can just check `inside`.
 */
export declare function stepFence(state: {
    fence: FenceState;
}, line: string): {
    fence: boolean;
    inside: boolean;
};