import type { Expr, AssignExpr, Pipeline, UpdateFilter } from "./ast.ts";
import { type GenerateCtx } from "./codegen.ts";
import { type SubPipelineLowerer, type SlotAllocator } from "./lookup-translation.ts";
export type OutTarget = {
    kind: "same-db";
    coll: string;
    pos: number;
} | {
    kind: "cross-db";
    db: string;
    coll: string;
    pos: number;
};
/**
 * Recognise the `$out` LHS shape on an `AssignExpr.target`. Returns the
 * extracted target on a match, or `null` if the shape isn't even close to
 * `$out`-like — in which case the caller falls through to its other branches
 * (replace-root, lookup, regular update op, etc.).
 *
 * When the shape *is* `$out`-like but malformed (wrong segment count,
 * computed bracket), this throws a precise `CodegenError` — that's what we
 * want, because the user clearly meant to address a collection but the
 * shape doesn't quite parse as one.
 */
export declare function detectOutAssign(op: AssignExpr, ctx?: GenerateCtx): OutTarget | null;
/**
 * Walk the RHS chain rooted at `$$` (CollectionRef) and emit the prefix
 * pipeline stages, left-to-right. Returns the (possibly empty) stage list;
 * the caller appends the final `$out` stage.
 *
 * Supported RHS shapes:
 *   - bare `$$`                                    → []
 *   - `$$.filter(<predicate>)`                     → [{ $match: ... }]
 *   - chained stream-methods registry methods
 *     (`.slice`, `.map`, `.toSorted`, `.toReversed`,
 *     `.flatMap`, `.concat`) compose freely        → [<their stages>...]
 *
 * Unrecognised methods throw an actionable error naming the
 * stage-call alternative.
 */
export declare function lowerOutChain(rhs: Expr, outerCtx: GenerateCtx, lowerBlock: SubPipelineLowerer, allocSlot: SlotAllocator): object[];
/**
 * Compose RHS-prefix stages with the trailing `{ $out: <target> }`. Returns
 * the stage list to splice into the surrounding pipeline. The caller is
 * responsible for flushing any preceding update-op buffer and setting the
 * "saw $out" flag so subsequent statements throw the trailing-stage error.
 */
export declare function lowerOut(op: AssignExpr, target: OutTarget, outerCtx: GenerateCtx, lowerBlock: SubPipelineLowerer, allocSlot: SlotAllocator): object[];
/**
 * Cheap walk: does `node` contain an `$out` assignment? Used by Filter /
 * `jsmql.expr` mode gates to surface a precise "use Pipeline mode" error.
 * Recognising only the canonical AssignExpr-target shape (one or two
 * static accesses on `DatabaseRef`/`ClusterRef`) is enough — anything else
 * never participates in `$out` lowering anyway.
 */
export declare function containsOutAssign(node: Expr | Pipeline | UpdateFilter): boolean;
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