/**
 * Per-document state, with a retention rule.
 *
 * The server rebuilds document state on a debounce, and a failed parse
 * produces no state at all. Features that answer a request per keystroke
 * therefore see "no state" constantly while the user types a line — most
 * of the time the buffer is simply half-written.
 *
 * For a feature like go-to-definition that is fine: no state, no answer,
 * and the user sees nothing missing. For semantic tokens it is not, because
 * "no answer" means every color in the file disappears until the line
 * parses again.
 *
 * So this cache keeps two things per document: the CURRENT state, which
 * goes away when a parse fails, and the LAST GOOD state, which does not.
 * Callers that need an answer on every keystroke read `getLastGood`.
 * Colors lagging the cursor by a debounce are invisible; colors
 * vanishing are not.
 *
 * It lives in its own module rather than as two Maps inside `startServer`
 * so the retention rule has one home instead of being re-decided at each
 * call site, and so it can be tested — the behaviour it exists for only
 * shows up across a sequence of updates.
 */
import type { DocumentState } from "./documentState.js";
export declare class DocumentStateCache {
    private current;
    private lastGood;
    /** Record a successful build. */
    set(uri: string, state: DocumentState): void;
    /** Record that the document no longer has usable state — a failed
     *  parse. The last good state deliberately survives. */
    clearCurrent(uri: string): void;
    /** The state for this document right now, or undefined if the latest
     *  parse failed. */
    get(uri: string): DocumentState | undefined;
    /**
     * The most recent state that parsed, even if the buffer has since
     * stopped parsing or moved on. May be older than the document — a
     * caller that cares can compare `state.version` against the document,
     * but for highlighting, stale beats absent.
     */
    getLastGood(uri: string): DocumentState | undefined;
    /** Forget the document entirely. For close, where retention would be
     *  a leak rather than a feature. */
    remove(uri: string): void;
    /** Any current state, for requests that are document-independent
     *  (workspace symbols). */
    anyCurrent(): DocumentState | undefined;
}