Method addToSource

lib/InitFragment.js:108–178

* Adds the provided source to the init fragment. * @template Context * @param {Source} source sources * @param {MaybeMergeableInitFragment<Context>[]} initFragments init fragments * @param {Context} context context * @returns {Source} source

(source, initFragments, context)

	 * @returns {Source} source
	 */
	static addToSource(source, initFragments, context) {
		if (initFragments.length > 0) {
			// Sort fragments by position. If 2 fragments have the same position,
			// use their index.
			const sortedFragments = initFragments
				.map(extractFragmentIndex)
				.sort(sortFragmentWithIndex);

			// Deduplicate fragments. If a fragment has no key, it is always included.
			/** @type {Map<InitFragmentKey | symbol, MaybeMergeableInitFragment<Context> | MaybeMergeableInitFragment<Context>[]>} */
			const keyedFragments = new Map();
			for (const [fragment] of sortedFragments) {
				if (typeof fragment.mergeAll === "function") {
					if (!fragment.key) {
						throw new Error(
							`InitFragment with mergeAll function must have a valid key: ${fragment.constructor.name}`
						);
					}
					const oldValue = keyedFragments.get(fragment.key);
					if (oldValue === undefined) {
						keyedFragments.set(fragment.key, fragment);
					} else if (Array.isArray(oldValue)) {
						oldValue.push(fragment);
					} else {
						keyedFragments.set(fragment.key, [oldValue, fragment]);
					}
					continue;
				} else if (typeof fragment.merge === "function") {
					const key = /** @type {InitFragmentKey} */ (fragment.key);
					const oldValue =
						/** @type {MaybeMergeableInitFragment<Context>} */
						(keyedFragments.get(key));
					if (oldValue !== undefined) {
						keyedFragments.set(key, fragment.merge(oldValue));
						continue;
					}
				}
				keyedFragments.set(fragment.key || Symbol("fragment key"), fragment);
			}

			const concatSource = new ConcatSource();
			/** @type {(string | Source)[]} */
			const endContents = [];
			for (let fragment of keyedFragments.values()) {
				if (Array.isArray(fragment)) {
					fragment =
						/** @type {[MaybeMergeableInitFragment<Context> & { mergeAll: (fragments: MaybeMergeableInitFragment<Context>[]) => MaybeMergeableInitFragment<Context>[] }, ...MaybeMergeableInitFragment<Context>[]]} */
						(fragment)[0].mergeAll(fragment);
				}
				const content =
					/** @type {MaybeMergeableInitFragment<Context>} */
					(fragment).getContent(context);
				if (content) {
					concatSource.add(content);
				}
				const endContent =
					/** @type {MaybeMergeableInitFragment<Context>} */
					(fragment).getEndContent(context);