import type { UnitsProvider } from "./Interfaces";
/**
 * Options for [[createUnitsProvider]].
 * @beta
 */
export interface CreateUnitsProviderOptions {
    /**
     * A `UnitsProvider` consulted before the basic BIS units (e.g. a `SchemaUnitProvider`
     * for an open iModel's `SchemaContext`). When omitted, the returned provider behaves
     * exactly like `new BasicUnitsProvider()`.
     */
    primary?: UnitsProvider;
    /**
     * Controls which provider is consulted first and wins ties.
     * - `"preferSchema"` (default): `primary` is authoritative; bundled BIS units are fallback.
     * - `"preferBundled"`: bundled BIS units win; `primary` is consulted only for units not in
     *   the bundled set. Use when the iModel's schema may be stale.
     *
     * Affects `findUnit`, `findUnitByName`, and `getConversion` (first-consulted wins or
     * falls through). `getUnitsByFamily` always merges both providers — the first-consulted
     * provider wins name collisions.
     *
     * Has no effect when `primary` is omitted — the returned provider is a plain `BasicUnitsProvider`.
     */
    bisUnitsPolicy?: "preferSchema" | "preferBundled";
}
/**
 * Returns a `UnitsProvider` that layers the basic BIS units under (or over) an optional
 * `primary` provider. Typical use: layer an iModel's schema units on top of the bundled
 * defaults from `@itwin/core-quantity`.
 *
 * Precedence rules:
 * - When `primary` is supplied and `bisUnitsPolicy` is `"preferSchema"` (the default): `primary` wins;
 *   basic BIS units fill any gaps where `primary` returns an invalid unit or throws.
 * - When `bisUnitsPolicy` is `"preferBundled"`: basic BIS units win; `primary` is consulted only when the
 *   basic provider can't answer.
 * - `getUnitsByFamily` always merges results from both providers, deduplicated by
 *   `UnitProps.name` (fully-qualified). The first-consulted provider wins ties.
 * - When no `primary` is supplied, the returned provider is exactly `new BasicUnitsProvider()`
 *   (no wrapper), preserving `instanceof` checks and keeping the hot path fast.
 *
 * @beta
 */
export declare function createUnitsProvider(options?: CreateUnitsProviderOptions): UnitsProvider;
//# sourceMappingURL=CompositeUnitsProvider.d.ts.map