/**
 * Value comparison for the components that select from a list.
 *
 * A near-verbatim port of upstream's `internals/itemEquality.ts` — it is pure
 * value logic with no DOM in it. `findSelectionIndex` is the one export left
 * behind: it exists upstream to drive the highlighted index, and there is no
 * highlight on mobile.
 *
 * The default is `Object.is`, so a value only ever matches itself. Object values
 * therefore need a comparer — that is what `isItemEqualToValue` is for.
 */
export type ItemEqualityComparer<Item = any, Value = Item> = (itemValue: Item, selectedValue: Value) => boolean;
export declare const defaultItemEquality: ItemEqualityComparer;
/**
 * Compares one item value against one selected value.
 *
 * `null` and `undefined` never reach the comparer: a consumer writing
 * `(a, b) => a.id === b.id` should not have to guard against an empty selection.
 */
export declare function compareItemEquality<Item, Value>(itemValue: Item, selectedValue: Value, comparer: ItemEqualityComparer<Item, Value>): boolean;
/**
 * Whether a multiple selection contains `itemValue`.
 */
export declare function selectedValueIncludes<Item, Value>(selectedValues: readonly Item[] | undefined | null, itemValue: Value, comparer: ItemEqualityComparer<Value, Item>): boolean;
/**
 * The index of the item matching `selectedValue`, or `-1`.
 */
export declare function findItemIndex<Item, Value>(itemValues: readonly Item[] | undefined | null, selectedValue: Value, comparer: ItemEqualityComparer<Item, Value>): number;
/**
 * A multiple selection with `itemValue` taken out.
 */
export declare function removeItem<Item, Value>(selectedValues: readonly Item[], itemValue: Value, comparer: ItemEqualityComparer<Value, Item>): Item[];
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