webpack/lib/InitFragment.js

Packs ECMAScript/CommonJs/AMD modules for the browser. Allows you to split your codebase into multiple bundles, which can be loaded on demand. Supports loaders to preprocess files, i.e. json, jsx, es7, css, less, ... and your custom stuff.

/*
	MIT License http://www.opensource.org/licenses/mit-license.php
	Author Florent Cailhol @ooflorent
*/

"use strict";

const { ConcatSource } = require("webpack-sources");
const makeSerializable = require("./util/makeSerializable");

/** @typedef {import("webpack-sources").Source} Source */
/** @typedef {import("./Generator").GenerateContext} GenerateContext */
/** @typedef {import("./serialization/ObjectMiddleware").ObjectDeserializerContext} ObjectDeserializerContext */
/** @typedef {import("./serialization/ObjectMiddleware").ObjectSerializerContext} ObjectSerializerContext */

/** @typedef {string} InitFragmentKey */

/**
 * Defines the maybe mergeable init fragment type used by this module.
 * @template GenerateContext
 * @typedef {object} MaybeMergeableInitFragment
 * @property {InitFragmentKey=} key
 * @property {number} stage
 * @property {number} position
 * @property {(context: GenerateContext) => string | Source | undefined} getContent
 * @property {(context: GenerateContext) => string | Source | undefined} getEndContent
 * @property {(fragments: MaybeMergeableInitFragment<GenerateContext>) => MaybeMergeableInitFragment<GenerateContext>=} merge
 * @property {(fragments: MaybeMergeableInitFragment<GenerateContext>[]) => MaybeMergeableInitFragment<GenerateContext>[]=} mergeAll
 */

/**
 * Represents InitFragment.
 * @template GenerateContext
 * @implements {MaybeMergeableInitFragment<GenerateContext>}
 */
class InitFragment {
	/**
	 * Creates an instance of InitFragment.
	 * @param {string | Source | undefined} content the source code that will be included as initialization code
	 * @param {number} stage category of initialization code (contribute to order)
	 * @param {number} position position in the category (contribute to order)
	 * @param {InitFragmentKey=} key unique key to avoid emitting the same initialization code twice
	 * @param {string | Source=} endContent the source code that will be included at the end of the module
	 */
	constructor(content, stage, position, key, endContent) {
		/** @type {string | Source | undefined} */
		this.content = content;
		/** @type {number} */
		this.stage = stage;
		/** @type {number} */
		this.position = position;
		/** @type {string | undefined} */
		this.key = key;
		/** @type {string | Source | undefined} */
		this.endContent = endContent;
	}

	/**
	 * Returns the source code that will be included as initialization code.
	 * @param {GenerateContext} context context
	 * @returns {string | Source | undefined} the source code that will be included as initialization code
	 */
	getContent(context) {
		return this.content;
	}

	/**
	 * Returns the source code that will be included at the end of the module.
	 * @param {GenerateContext} context context
	 * @returns {string | Source | undefined} the source code that will be included at the end of the module
	 */
	getEndContent(context) {
		return this.endContent;
	}

	/**
	 * 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
	 */
	static addToSource(source, initFragments, context) {
		if (initFragments.length > 0) {
			// Sort fragment indices by (stage, position), falling back to the
			// original index — one flat number array instead of N [fragment, index]
			// tuples for a stable-by-index order.
			const sortedIndices = initFragments.map((_, index) => index);
			sortedIndices.sort((a, b) => {
				const fragmentA = initFragments[a];
				const fragmentB = initFragments[b];
				const stageCmp = fragmentA.stage - fragmentB.stage;
				if (stageCmp !== 0) return stageCmp;
				const positionCmp = fragmentA.position - fragmentB.position;
				if (positionCmp !== 0) return positionCmp;
				return a - b;
			});

			// Deduplicate fragments. If a fragment has no key, it is always included.
			// Keyless fragments get a unique numeric key; number keys never collide
			// with the string `InitFragmentKey`s used for keyed fragments.
			/** @type {Map<InitFragmentKey | number, MaybeMergeableInitFragment<Context> | MaybeMergeableInitFragment<Context>[]>} */
			const keyedFragments = new Map();
			let keylessKey = 0;
			for (const index of sortedIndices) {
				const fragment = initFragments[index];
				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 || keylessKey++, 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);
				if (endContent) {
					endContents.push(endContent);
				}
			}

			concatSource.add(source);
			for (const content of endContents.reverse()) {
				concatSource.add(content);
			}
			return concatSource;
		}
		return source;
	}

	/**
	 * Serializes this instance into the provided serializer context.
	 * @param {ObjectSerializerContext} context context
	 */
	serialize(context) {
		const { write } = context;

		write(this.content);
		write(this.stage);
		write(this.position);
		write(this.key);
		write(this.endContent);
	}

	/**
	 * Restores this instance from the provided deserializer context.
	 * @param {ObjectDeserializerContext} context context
	 */
	deserialize(context) {
		const { read } = context;

		this.content = read();
		this.stage = read();
		this.position = read();
		this.key = read();
		this.endContent = read();
	}
}

makeSerializable(InitFragment, "webpack/lib/InitFragment");

InitFragment.STAGE_CONSTANTS = 10;
InitFragment.STAGE_ASYNC_BOUNDARY = 20;
InitFragment.STAGE_HARMONY_EXPORTS = 30;
InitFragment.STAGE_HARMONY_IMPORTS = 40;
InitFragment.STAGE_PROVIDES = 50;
InitFragment.STAGE_ASYNC_DEPENDENCIES = 60;
InitFragment.STAGE_ASYNC_HARMONY_IMPORTS = 70;

module.exports = InitFragment;