webpack/lib/util/haltVisitors.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 Alexander Akait @alexander-akait
*/

"use strict";

/**
 * @template T
 * @typedef {import("./SourceProcessor").VisitorFn<T>} VisitorFn
 */
/**
 * @template T
 * @typedef {import("./SourceProcessor").CompiledVisitorBucket<T>} CompiledVisitorBucket
 */

/**
 * Empty every bucket of a compiled visitor map in place, so a dispatch loop
 * running over one ends after the visitor that asked and none fires again.
 * @template TPath
 * @param {CompiledVisitorBucket<TPath>[]} map the map a walk dispatches from
 * @returns {VisitorFn<TPath>[][]} each emptied list followed by its visitors, for {@link resumeVisitors}
 */
const haltVisitors = (map) => {
	/** @type {VisitorFn<TPath>[][]} */
	const halted = [];
	for (let type = 0; type < map.length; type++) {
		const bucket = map[type];
		if (bucket === undefined) continue;
		halted.push(bucket.enter, [...bucket.enter], bucket.exit, [...bucket.exit]);
		bucket.enter.length = 0;
		bucket.exit.length = 0;
	}
	return halted;
};

/**
 * Put back what {@link haltVisitors} emptied, so the next walk fires them all.
 * @template TPath
 * @param {VisitorFn<TPath>[][]} halted what `haltVisitors` returned
 */
const resumeVisitors = (halted) => {
	for (let i = 0; i < halted.length; i += 2) {
		const list = halted[i];
		const visitors = halted[i + 1];
		for (let k = 0; k < visitors.length; k++) list.push(visitors[k]);
	}
};

module.exports.haltVisitors = haltVisitors;
module.exports.resumeVisitors = resumeVisitors;