/**
 * SQL Mode 2 — JOIN Translator
 *
 * INNER JOIN → $lookup + $unwind
 * LEFT JOIN → $lookup + $unwind (preserveNullAndEmptyArrays: true)
 * RIGHT JOIN → swap collections, LEFT JOIN
 * FULL OUTER JOIN → two pipelines merged
 * CROSS JOIN → $lookup with empty pipeline (cartesian product)
 */
import type { JoinInfo, PipelineDef } from '../types.js';
export interface JoinResult {
    stages: Record<string, unknown>[];
    /** For FULL OUTER JOINs, the second pipelines (one per FULL OUTER JOIN) */
    secondPipelines?: PipelineDef[];
    /** The main collection (may be swapped for RIGHT JOIN) */
    mainCollection?: string;
}
/**
 * Extract JOIN info from AST FROM clause.
 */
export declare function extractJoins(from: unknown): JoinInfo[];
/**
 * Translate JOINs into pipeline stages.
 * @param pushdownFilters — optional map of join alias/table → MongoDB filter to push into $lookup pipeline
 */
export declare function translateJoins(from: unknown, mainCollection: string, pushdownFilters?: Map<string, Record<string, unknown>>): JoinResult;
/**
 * Split a WHERE AST into conditions for the main table vs joined tables.
 * Returns main-table conditions and a map of joinAlias → conditions for pushdown.
 */
export declare function splitWhereByTable(where: unknown, mainAliases: Set<string>, joinAliases: Set<string>): {
    mainWhere: unknown;
    pushdownMap: Map<string, Record<string, unknown>>;
};
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