@everwhen/temporal/dist/fn/series.js

_description_

/**
 * A series wraps a list of values that should be
 * treated with order, providing methods to navigate
 * and compare items within the series.
 */
export class Series {
    #items;
    #indexesByKey;
    #itemsByIndex;
    #toKey;
    constructor(items, toKey = (item) => `${item}`) {
        this.#items = items;
        this.#toKey = toKey;
        this.#indexesByKey = new Map();
        this.#itemsByIndex = new Map();
        items.forEach((item, idx) => {
            this.#indexesByKey.set(toKey(item), idx);
            this.#itemsByIndex.set(idx, item);
        });
    }
    /**
     * Given two values in the series, returns the
     * value that occurs earlier in the series
     */
    min(a, b) {
        const idxA = this.#indexesByKey.get(this.#toKey(a)) ?? 0;
        const idxB = this.#indexesByKey.get(this.#toKey(b)) ?? 0;
        return idxA < idxB ? a : b;
    }
    /**
     * Given two values in the series, returns the
     * value that occurs later in the series
     */
    max(a, b) {
        const idxA = this.#indexesByKey.get(this.#toKey(a)) ?? 0;
        const idxB = this.#indexesByKey.get(this.#toKey(b)) ?? 0;
        return idxA > idxB ? a : b;
    }
    /**
     * Returns the first item from the series
     */
    first() {
        return this.#itemsByIndex.get(0);
    }
    /**
     * Returns the last item in the series
     */
    last() {
        return this.#itemsByIndex.get(this.#items.length - 1);
    }
    /**
     * Given an item in the series returns the next item
     * in the series or default if the given value is
     * the last item in the series
     */
    next(current, defaultValue) {
        const currentIdx = this.#indexesByKey.get(this.#toKey(current)) ?? -1;
        return (this.#itemsByIndex.get(currentIdx + 1) ?? defaultValue ?? this.first());
    }
    /**
     * Given an item in the series returns the previous item
     * in the series or default if the given value is
     * the first item in the series
     */
    previous(current, defaultValue) {
        const currentIdx = this.#indexesByKey.get(this.#toKey(current)) ?? 0;
        return this.#itemsByIndex.get(currentIdx - 1) ?? defaultValue ?? this.last();
    }
}