node_modules/enhanced-resolve/lib/FileExistsPlugin.js

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

module.exports = class FileExistsPlugin {
	constructor(source, target) {
		this.source = source;
		this.target = target;
	}

	apply(resolver) {
		const target = resolver.ensureHook(this.target);
		const fs = resolver.fileSystem;
		resolver
			.getHook(this.source)
			.tapAsync("FileExistsPlugin", (request, resolveContext, callback) => {
				const file = request.path;
				fs.stat(file, (err, stat) => {
					if (err || !stat) {
						if (resolveContext.missing) resolveContext.missing.add(file);
						if (resolveContext.log) resolveContext.log(file + " doesn't exist");
						return callback();
					}
					if (!stat.isFile()) {
						if (resolveContext.missing) resolveContext.missing.add(file);
						if (resolveContext.log) resolveContext.log(file + " is not a file");
						return callback();
					}
					resolver.doResolve(
						target,
						request,
						"existing file: " + file,
						resolveContext,
						callback
					);
				});
			});
	}
};