Method get

lib/util/StackedMap.js:116–135

* Returns the visible value for a key, caching parent hits and misses in the * current layer. * @param {K} item the key of the element to return * @returns {Cell<V>} the value of the element

(item)

	 * @returns {Cell<V>} the value of the element
	 */
	get(item) {
		const topValue = this.map.get(item);
		if (topValue !== undefined) {
			return topValue === TOMBSTONE || topValue === UNDEFINED_MARKER
				? undefined
				: topValue;
		}
		if (this.stack.length > 1) {
			for (let i = this.stack.length - 2; i >= 0; i--) {
				const value = this.stack[i].get(item);
				if (value !== undefined) {
					this.map.set(item, value);
					return value === TOMBSTONE || value === UNDEFINED_MARKER
						? undefined
						: value;
				}
			}
			this.map.set(item, TOMBSTONE);
		}
	}

	/**
	 * Collapses the stacked layers into a single concrete map.