@loken/hierarchies/dist/lib/traversal/sequence.types.d.ts

Library for working with hierarchies of identifiers and identifiable objects.

/**
 * Options for sequence traversal.
 *
 * You must either provide a delegate using a `signal` or a delegate simply providing the `next` nodes.
 */
export type SequenceTraversal<TEl> = {
    /** The first element of the traversal. */
    first: TEl | undefined;
} & ({
    /** Describes how to get the the next element while traversing a sequence. */
    next: NextElement<TEl>;
    /** Discriminated: Cannot pass a `signal` delegate when you've already passed a `next` delegate. */
    signal?: never;
} | {
    /** Describes how to traverse a sequence when visiting an element using an `ISequenceSignal`. */
    signal: SignalElement<TEl>;
    /** Discriminated: Cannot pass a `next` delegate when you've already passed a `signal` delegate. */
    next?: never;
});
/** Describes how to get the next element of the sequence. */
export type NextElement<TEl> = (element: TEl) => TEl | undefined;
/** Describes how to traverse a sequence when visiting an element using an `ISequenceSignal`. */
export type SignalElement<TEl> = (element: TEl, signal: ISequenceSignal<TEl>) => void;
/**
 * Use this to signal to the traversal what's `next` and what to `skip`.
 */
export interface ISequenceSignal<TEl> {
    /** The source index of the current element. */
    get index(): number;
    /** The number of elements returned so far. */
    get count(): number;
    /** Call this when traversal should continue to a sub sequence of child roots. */
    next(element?: TEl): void;
    /**
     * Call this when you want to signal that the current element should be skipped,
     * meaning it will not be part of the output.
     *
     * Traversal will still continue to an element passed to
     * `next` irrespective of calling `skip`.
     */
    skip(): void;
}
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