webpack/lib/InitFragment.js

Packs CommonJs/AMD modules for the browser. Allows to split your codebase into multiple bundles, which can be loaded on demand. Support 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");

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

/**
 * @param {InitFragment} fragment the init fragment
 * @param {number} index index
 * @returns {[InitFragment, number]} tuple with both
 */
const extractFragmentIndex = (fragment, index) => [fragment, index];

/**
 * @param {[InitFragment, number]} a first pair
 * @param {[InitFragment, number]} b second pair
 * @returns {number} sort value
 */
const sortFragmentWithIndex = ([a, i], [b, j]) => {
	const stageCmp = a.stage - b.stage;
	if (stageCmp !== 0) return stageCmp;
	const positionCmp = a.position - b.position;
	if (positionCmp !== 0) return positionCmp;
	return i - j;
};

class InitFragment {
	/**
	 * @param {string|Source} 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 {string=} 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) {
		this.content = content;
		this.stage = stage;
		this.position = position;
		this.key = key;
		this.endContent = endContent;
	}

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

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

	static addToSource(source, initFragments, generateContext) {
		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.
			const keyedFragments = new Map();
			for (const [fragment] of sortedFragments) {
				if (typeof fragment.merge === "function") {
					const oldValue = keyedFragments.get(fragment.key);
					if (oldValue !== undefined) {
						keyedFragments.set(
							fragment.key || Symbol(),
							fragment.merge(oldValue)
						);
						continue;
					}
				}
				keyedFragments.set(fragment.key || Symbol(), fragment);
			}

			const concatSource = new ConcatSource();
			const endContents = [];
			for (const fragment of keyedFragments.values()) {
				concatSource.add(fragment.getContent(generateContext));
				const endContent = fragment.getEndContent(generateContext);
				if (endContent) {
					endContents.push(endContent);
				}
			}

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

InitFragment.prototype.merge = undefined;

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;