/**
 * Postgres default constraint names.
 *
 * When a constraint is authored without a name, Postgres derives one at
 * deploy time (`ChooseConstraintName` in the server): `{table}_pkey` for
 * primary keys, `{table}_{cols}_key` for unique constraints,
 * `{table}_{col}_fkey` for foreign keys, `{table}_{col}_check` (first
 * referenced column) or `{table}_check` for check constraints. Synthesizing
 * the same names makes unnamed authorship comparable to (and revertible as)
 * what the catalog will actually contain.
 */
/** A parsed `Constraint` node (structural — the fields this module reads). */
export interface ConstraintNode {
    contype?: string;
    conname?: string;
    keys?: {
        String?: {
            sval?: string;
        };
    }[];
    fk_attrs?: {
        String?: {
            sval?: string;
        };
    }[];
    raw_expr?: unknown;
}
/** First `ColumnRef` column name reached in an expression tree, DFS order. */
export declare function firstColumnRef(node: unknown): string | null;
/**
 * The name Postgres would assign to an unnamed constraint on `table`, given
 * the constraint node and (for column-attached constraints) the owning
 * column. Returns `null` for kinds without a stable derivation (exclusion
 * constraints and anything unrecognized).
 */
export declare function defaultConstraintName(table: string, constraint: ConstraintNode, column?: string): string | null;