Function mergeEntries

lib/util/cleverMerge.js:400–523

(firstEntry, secondEntry, internalCaching)

 * @returns {ObjectParsedPropertyEntry<T> | ObjectParsedPropertyEntry<O> | ObjectParsedPropertyEntry<T & O>} new entry
 */
const mergeEntries = (firstEntry, secondEntry, internalCaching) => {
	switch (getValueType(secondEntry.base)) {
		case VALUE_TYPE_ATOM:
		case VALUE_TYPE_DELETE:
			// No need to consider firstEntry at all
			// second value override everything
			// = second.base + second.byProperty
			return secondEntry;
		case VALUE_TYPE_UNDEFINED:
			if (!firstEntry.byProperty) {
				// = first.base + second.byProperty
				return {
					base: firstEntry.base,
					byProperty: secondEntry.byProperty,
					byValues: secondEntry.byValues
				};
			} else if (firstEntry.byProperty !== secondEntry.byProperty) {
				throw new Error(
					`${firstEntry.byProperty} and ${secondEntry.byProperty} for a single property is not supported`
				);
			} else {
				// = first.base + (first.byProperty + second.byProperty)
				// need to merge first and second byValues
				/** @type {Map<string, T & O>} */
				const newByValues = new Map(firstEntry.byValues);
				for (const [key, value] of /** @type {ByValues} */ (
					secondEntry.byValues
				)) {
					const firstValue = getFromByValues(
						/** @type {ByValues} */
						(firstEntry.byValues),
						key
					);
					newByValues.set(
						key,
						mergeSingleValue(firstValue, value, internalCaching)
					);
				}
				return {
					base: firstEntry.base,
					byProperty: firstEntry.byProperty,
					byValues: newByValues
				};
			}
		default: {
			if (!firstEntry.byProperty) {
				// The simple case
				// = (first.base + second.base) + second.byProperty
				return {
					base:
						/** @type {T[keyof T] & O[keyof O]} */
						(
							mergeSingleValue(
								firstEntry.base,
								secondEntry.base,
								internalCaching
							)
						),