package.lib.util.compileBooleanMatcher.js Maven / Gradle / Ivy

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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.
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/*
	MIT License http://www.opensource.org/licenses/mit-license.php
	Author Tobias Koppers @sokra
*/

"use strict";

/**
 * @param {string} str string
 * @returns {string} quoted meta
 */
const quoteMeta = str => {
	return str.replace(/[-[\]\\/{}()*+?.^$|]/g, "\\$&");
};

/**
 * @param {string} str string
 * @returns {string} string
 */
const toSimpleString = str => {
	if (`${+str}` === str) {
		return str;
	}
	return JSON.stringify(str);
};

/**
 * @param {Record} map value map
 * @returns {boolean|(function(string): string)} true/false, when unconditionally true/false, or a template function to determine the value at runtime
 */
const compileBooleanMatcher = map => {
	const positiveItems = Object.keys(map).filter(i => map[i]);
	const negativeItems = Object.keys(map).filter(i => !map[i]);
	if (positiveItems.length === 0) return false;
	if (negativeItems.length === 0) return true;
	return compileBooleanMatcherFromLists(positiveItems, negativeItems);
};

/**
 * @param {string[]} positiveItems positive items
 * @param {string[]} negativeItems negative items
 * @returns {function(string): string} a template function to determine the value at runtime
 */
const compileBooleanMatcherFromLists = (positiveItems, negativeItems) => {
	if (positiveItems.length === 0) return () => "false";
	if (negativeItems.length === 0) return () => "true";
	if (positiveItems.length === 1)
		return value => `${toSimpleString(positiveItems[0])} == ${value}`;
	if (negativeItems.length === 1)
		return value => `${toSimpleString(negativeItems[0])} != ${value}`;
	const positiveRegexp = itemsToRegexp(positiveItems);
	const negativeRegexp = itemsToRegexp(negativeItems);
	if (positiveRegexp.length <= negativeRegexp.length) {
		return value => `/^${positiveRegexp}$/.test(${value})`;
	} else {
		return value => `!/^${negativeRegexp}$/.test(${value})`;
	}
};

/**
 * @param {Set} itemsSet items set
 * @param {(str: string) => string | false} getKey get key function
 * @param {(str: Array) => boolean} condition condition
 * @returns {Array>} list of common items
 */
const popCommonItems = (itemsSet, getKey, condition) => {
	/** @type {Map>} */
	const map = new Map();
	for (const item of itemsSet) {
		const key = getKey(item);
		if (key) {
			let list = map.get(key);
			if (list === undefined) {
				/** @type {Array} */
				list = [];
				map.set(key, list);
			}
			list.push(item);
		}
	}
	/** @type {Array>} */
	const result = [];
	for (const list of map.values()) {
		if (condition(list)) {
			for (const item of list) {
				itemsSet.delete(item);
			}
			result.push(list);
		}
	}
	return result;
};

/**
 * @param {Array} items items
 * @returns {string} common prefix
 */
const getCommonPrefix = items => {
	let prefix = items[0];
	for (let i = 1; i < items.length; i++) {
		const item = items[i];
		for (let p = 0; p < prefix.length; p++) {
			if (item[p] !== prefix[p]) {
				prefix = prefix.slice(0, p);
				break;
			}
		}
	}
	return prefix;
};

/**
 * @param {Array} items items
 * @returns {string} common suffix
 */
const getCommonSuffix = items => {
	let suffix = items[0];
	for (let i = 1; i < items.length; i++) {
		const item = items[i];
		for (let p = item.length - 1, s = suffix.length - 1; s >= 0; p--, s--) {
			if (item[p] !== suffix[s]) {
				suffix = suffix.slice(s + 1);
				break;
			}
		}
	}
	return suffix;
};

/**
 * @param {Array} itemsArr array of items
 * @returns {string} regexp
 */
const itemsToRegexp = itemsArr => {
	if (itemsArr.length === 1) {
		return quoteMeta(itemsArr[0]);
	}
	/** @type {Array} */
	const finishedItems = [];

	// merge single char items: (a|b|c|d|ef) => ([abcd]|ef)
	let countOfSingleCharItems = 0;
	for (const item of itemsArr) {
		if (item.length === 1) {
			countOfSingleCharItems++;
		}
	}
	// special case for only single char items
	if (countOfSingleCharItems === itemsArr.length) {
		return `[${quoteMeta(itemsArr.sort().join(""))}]`;
	}
	const items = new Set(itemsArr.sort());
	if (countOfSingleCharItems > 2) {
		let singleCharItems = "";
		for (const item of items) {
			if (item.length === 1) {
				singleCharItems += item;
				items.delete(item);
			}
		}
		finishedItems.push(`[${quoteMeta(singleCharItems)}]`);
	}

	// special case for 2 items with common prefix/suffix
	if (finishedItems.length === 0 && items.size === 2) {
		const prefix = getCommonPrefix(itemsArr);
		const suffix = getCommonSuffix(
			itemsArr.map(item => item.slice(prefix.length))
		);
		if (prefix.length > 0 || suffix.length > 0) {
			return `${quoteMeta(prefix)}${itemsToRegexp(
				itemsArr.map(i => i.slice(prefix.length, -suffix.length || undefined))
			)}${quoteMeta(suffix)}`;
		}
	}

	// special case for 2 items with common suffix
	if (finishedItems.length === 0 && items.size === 2) {
		/** @type {Iterator} */
		const it = items[Symbol.iterator]();
		const a = it.next().value;
		const b = it.next().value;
		if (a.length > 0 && b.length > 0 && a.slice(-1) === b.slice(-1)) {
			return `${itemsToRegexp([a.slice(0, -1), b.slice(0, -1)])}${quoteMeta(
				a.slice(-1)
			)}`;
		}
	}

	// find common prefix: (a1|a2|a3|a4|b5) => (a(1|2|3|4)|b5)
	const prefixed = popCommonItems(
		items,
		item => (item.length >= 1 ? item[0] : false),
		list => {
			if (list.length >= 3) return true;
			if (list.length <= 1) return false;
			return list[0][1] === list[1][1];
		}
	);
	for (const prefixedItems of prefixed) {
		const prefix = getCommonPrefix(prefixedItems);
		finishedItems.push(
			`${quoteMeta(prefix)}${itemsToRegexp(
				prefixedItems.map(i => i.slice(prefix.length))
			)}`
		);
	}

	// find common suffix: (a1|b1|c1|d1|e2) => ((a|b|c|d)1|e2)
	const suffixed = popCommonItems(
		items,
		item => (item.length >= 1 ? item.slice(-1) : false),
		list => {
			if (list.length >= 3) return true;
			if (list.length <= 1) return false;
			return list[0].slice(-2) === list[1].slice(-2);
		}
	);
	for (const suffixedItems of suffixed) {
		const suffix = getCommonSuffix(suffixedItems);
		finishedItems.push(
			`${itemsToRegexp(
				suffixedItems.map(i => i.slice(0, -suffix.length))
			)}${quoteMeta(suffix)}`
		);
	}

	// TODO further optimize regexp, i. e.
	// use ranges: (1|2|3|4|a) => [1-4a]
	const conditional = finishedItems.concat(Array.from(items, quoteMeta));
	if (conditional.length === 1) return conditional[0];
	return `(${conditional.join("|")})`;
};

compileBooleanMatcher.fromLists = compileBooleanMatcherFromLists;
compileBooleanMatcher.itemsToRegexp = itemsToRegexp;
module.exports = compileBooleanMatcher;