webpack/lib/util/conventions.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 Gengkun He @ahabhgk
*/

"use strict";

/** @typedef {import("../../declarations/WebpackOptions").CssGeneratorExportsConvention} CssGeneratorExportsConvention */
// Copy from css-loader
/**
 * Preserve camel case.
 * @param {string} string string
 * @returns {string} result
 */
const preserveCamelCase = (string) => {
	let result = string;
	let isLastCharLower = false;
	let isLastCharUpper = false;
	let isLastLastCharUpper = false;

	for (let i = 0; i < result.length; i++) {
		const character = result[i];

		if (isLastCharLower && /\p{Lu}/u.test(character)) {
			result = `${result.slice(0, i)}-${result.slice(i)}`;
			isLastCharLower = false;
			isLastLastCharUpper = isLastCharUpper;
			isLastCharUpper = true;
			i += 1;
		} else if (
			isLastCharUpper &&
			isLastLastCharUpper &&
			/\p{Ll}/u.test(character)
		) {
			result = `${result.slice(0, i - 1)}-${result.slice(i - 1)}`;
			isLastLastCharUpper = isLastCharUpper;
			isLastCharUpper = false;
			isLastCharLower = true;
		} else {
			isLastCharLower =
				character.toLowerCase() === character &&
				character.toUpperCase() !== character;
			isLastLastCharUpper = isLastCharUpper;
			isLastCharUpper =
				character.toUpperCase() === character &&
				character.toLowerCase() !== character;
		}
	}

	return result;
};

// Copy from css-loader
/**
 * Returns result.
 * @param {string} input input
 * @returns {string} result
 */
module.exports.camelCase = (input) => {
	let result = input.trim();

	if (result.length === 0) {
		return "";
	}

	if (result.length === 1) {
		return result.toLowerCase();
	}

	const hasUpperCase = result !== result.toLowerCase();

	if (hasUpperCase) {
		result = preserveCamelCase(result);
	}

	return result
		.replace(/^[_.\- ]+/, "")
		.toLowerCase()
		.replace(/[_.\- ]+([\p{Alpha}\p{N}_]|$)/gu, (_, p1) => p1.toUpperCase())
		.replace(/\d+([\p{Alpha}\p{N}_]|$)/gu, (m) => m.toUpperCase());
};

/**
 * Safely stringify an arbitrary value for an error message — falls back to
 * `String(...)` when JSON.stringify would throw (BigInt, circular, etc.).
 * @param {EXPECTED_ANY} value value to stringify
 * @returns {string} stringified value
 */
const safeStringify = (value) => {
	try {
		const json = JSON.stringify(value);
		if (json !== undefined) return json;
	} catch (_err) {
		// fall through to String fallback
	}
	try {
		return String(value);
	} catch (_err) {
		return "[value cannot be converted to string]";
	}
};

/**
 * Returns results.
 * @param {string} input input
 * @param {CssGeneratorExportsConvention | undefined} convention convention
 * @returns {string[]} results
 */
module.exports.cssExportConvention = (input, convention) => {
	/** @type {Set<string>} */
	const set = new Set();
	if (typeof convention === "function") {
		const result = convention(input);
		const validate = (/** @type {string} */ name) => {
			if (typeof name !== "string" || name.length === 0) {
				throw new Error(
					`exportsConvention function must return a non-empty string or an array of non-empty strings, got ${safeStringify(result)}`
				);
			}
		};
		if (Array.isArray(result)) {
			if (result.length === 0) {
				throw new Error(
					"exportsConvention function returned an empty array; it must return at least one name"
				);
			}
			for (const name of result) {
				validate(name);
				set.add(name);
			}
		} else {
			validate(result);
			set.add(result);
		}
	} else {
		switch (convention) {
			case "camel-case": {
				set.add(input);
				set.add(module.exports.camelCase(input));
				break;
			}
			case "camel-case-only": {
				set.add(module.exports.camelCase(input));
				break;
			}
			case "dashes": {
				set.add(input);
				set.add(module.exports.dashesCamelCase(input));
				break;
			}
			case "dashes-only": {
				set.add(module.exports.dashesCamelCase(input));
				break;
			}
			case "as-is": {
				set.add(input);
				break;
			}
		}
	}
	return [...set];
};

// Copy from css-loader
/**
 * Returns result.
 * @param {string} input input
 * @returns {string} result
 */
module.exports.dashesCamelCase = (input) =>
	input.replace(/-+(\w)/g, (match, firstLetter) => firstLetter.toUpperCase());