export declare class PreparedStatementCache {
    #private;
    constructor(size: number);
    /**
     * Attempts to look up the cached sql statement, if it's currently cached.
     */
    lookup(sql: string): number | null;
    /**
     * Adds a new statement into the cache.
     *
     * If that exceeds the target size of the statement cache, returns an old statement to evict.
     * The caller is responsible for freeing that statement.
     */
    addStatement(sql: string, statement: number): number | null;
    drain(): number[];
}