forked from M3-Academy/challenge-algorithms-v2.0
370 lines
8.7 KiB
JavaScript
370 lines
8.7 KiB
JavaScript
// vendored from https://github.com/amasad/sane/blob/64ff3a870c42e84f744086884bf55a4f9c22d376/src/node_watcher.js
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'use strict';
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const EventEmitter = require('events').EventEmitter;
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const fs = require('fs');
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const platform = require('os').platform();
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const path = require('path');
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const common = require('./common');
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/**
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* Constants
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*/
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const DEFAULT_DELAY = common.DEFAULT_DELAY;
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const CHANGE_EVENT = common.CHANGE_EVENT;
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const DELETE_EVENT = common.DELETE_EVENT;
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const ADD_EVENT = common.ADD_EVENT;
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const ALL_EVENT = common.ALL_EVENT;
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/**
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* Export `NodeWatcher` class.
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* Watches `dir`.
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*
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* @class NodeWatcher
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* @param {String} dir
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* @param {Object} opts
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* @public
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*/
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module.exports = class NodeWatcher extends EventEmitter {
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constructor(dir, opts) {
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super();
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common.assignOptions(this, opts);
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this.watched = Object.create(null);
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this.changeTimers = Object.create(null);
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this.dirRegistery = Object.create(null);
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this.root = path.resolve(dir);
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this.watchdir = this.watchdir.bind(this);
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this.register = this.register.bind(this);
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this.checkedEmitError = this.checkedEmitError.bind(this);
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this.watchdir(this.root);
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common.recReaddir(
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this.root,
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this.watchdir,
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this.register,
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this.emit.bind(this, 'ready'),
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this.checkedEmitError,
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this.ignored
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);
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}
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/**
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* Register files that matches our globs to know what to type of event to
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* emit in the future.
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*
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* Registery looks like the following:
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*
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* dirRegister => Map {
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* dirpath => Map {
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* filename => true
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* }
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* }
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*
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* @param {string} filepath
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* @return {boolean} whether or not we have registered the file.
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* @private
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*/
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register(filepath) {
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const relativePath = path.relative(this.root, filepath);
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if (
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!common.isFileIncluded(this.globs, this.dot, this.doIgnore, relativePath)
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) {
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return false;
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}
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const dir = path.dirname(filepath);
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if (!this.dirRegistery[dir]) {
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this.dirRegistery[dir] = Object.create(null);
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}
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const filename = path.basename(filepath);
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this.dirRegistery[dir][filename] = true;
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return true;
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}
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/**
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* Removes a file from the registery.
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*
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* @param {string} filepath
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* @private
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*/
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unregister(filepath) {
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const dir = path.dirname(filepath);
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if (this.dirRegistery[dir]) {
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const filename = path.basename(filepath);
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delete this.dirRegistery[dir][filename];
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}
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}
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/**
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* Removes a dir from the registery.
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*
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* @param {string} dirpath
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* @private
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*/
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unregisterDir(dirpath) {
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if (this.dirRegistery[dirpath]) {
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delete this.dirRegistery[dirpath];
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}
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}
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/**
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* Checks if a file or directory exists in the registery.
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*
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* @param {string} fullpath
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* @return {boolean}
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* @private
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*/
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registered(fullpath) {
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const dir = path.dirname(fullpath);
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return (
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this.dirRegistery[fullpath] ||
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(this.dirRegistery[dir] &&
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this.dirRegistery[dir][path.basename(fullpath)])
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);
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}
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/**
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* Emit "error" event if it's not an ignorable event
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*
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* @param error
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* @private
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*/
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checkedEmitError(error) {
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if (!isIgnorableFileError(error)) {
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this.emit('error', error);
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}
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}
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/**
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* Watch a directory.
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*
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* @param {string} dir
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* @private
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*/
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watchdir(dir) {
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if (this.watched[dir]) {
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return;
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}
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const watcher = fs.watch(
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dir,
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{
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persistent: true
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},
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this.normalizeChange.bind(this, dir)
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);
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this.watched[dir] = watcher;
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watcher.on('error', this.checkedEmitError);
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if (this.root !== dir) {
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this.register(dir);
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}
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}
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/**
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* Stop watching a directory.
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*
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* @param {string} dir
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* @private
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*/
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stopWatching(dir) {
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if (this.watched[dir]) {
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this.watched[dir].close();
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delete this.watched[dir];
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}
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}
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/**
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* End watching.
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*
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* @public
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*/
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close() {
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Object.keys(this.watched).forEach(this.stopWatching, this);
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this.removeAllListeners();
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return Promise.resolve();
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}
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/**
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* On some platforms, as pointed out on the fs docs (most likely just win32)
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* the file argument might be missing from the fs event. Try to detect what
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* change by detecting if something was deleted or the most recent file change.
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*
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* @param {string} dir
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* @param {string} event
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* @param {string} file
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* @public
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*/
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detectChangedFile(dir, event, callback) {
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if (!this.dirRegistery[dir]) {
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return;
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}
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let found = false;
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let closest = {
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mtime: 0
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};
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let c = 0;
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Object.keys(this.dirRegistery[dir]).forEach(function (file, i, arr) {
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fs.lstat(path.join(dir, file), (error, stat) => {
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if (found) {
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return;
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}
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if (error) {
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if (isIgnorableFileError(error)) {
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found = true;
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callback(file);
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} else {
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this.emit('error', error);
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}
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} else {
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if (stat.mtime > closest.mtime) {
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stat.file = file;
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closest = stat;
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}
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if (arr.length === ++c) {
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callback(closest.file);
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}
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}
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});
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}, this);
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}
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/**
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* Normalize fs events and pass it on to be processed.
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*
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* @param {string} dir
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* @param {string} event
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* @param {string} file
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* @public
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*/
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normalizeChange(dir, event, file) {
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if (!file) {
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this.detectChangedFile(dir, event, actualFile => {
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if (actualFile) {
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this.processChange(dir, event, actualFile);
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}
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});
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} else {
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this.processChange(dir, event, path.normalize(file));
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}
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}
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/**
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* Process changes.
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*
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* @param {string} dir
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* @param {string} event
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* @param {string} file
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* @public
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*/
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processChange(dir, event, file) {
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const fullPath = path.join(dir, file);
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const relativePath = path.join(path.relative(this.root, dir), file);
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fs.lstat(fullPath, (error, stat) => {
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if (error && error.code !== 'ENOENT') {
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this.emit('error', error);
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} else if (!error && stat.isDirectory()) {
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// win32 emits usless change events on dirs.
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if (event !== 'change') {
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this.watchdir(fullPath);
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if (
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common.isFileIncluded(
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this.globs,
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this.dot,
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this.doIgnore,
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relativePath
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)
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) {
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this.emitEvent(ADD_EVENT, relativePath, stat);
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}
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}
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} else {
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const registered = this.registered(fullPath);
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if (error && error.code === 'ENOENT') {
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this.unregister(fullPath);
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this.stopWatching(fullPath);
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this.unregisterDir(fullPath);
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if (registered) {
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this.emitEvent(DELETE_EVENT, relativePath);
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}
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} else if (registered) {
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this.emitEvent(CHANGE_EVENT, relativePath, stat);
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} else {
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if (this.register(fullPath)) {
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this.emitEvent(ADD_EVENT, relativePath, stat);
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}
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}
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}
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});
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}
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/**
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* Triggers a 'change' event after debounding it to take care of duplicate
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* events on os x.
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*
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* @private
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*/
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emitEvent(type, file, stat) {
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const key = `${type}-${file}`;
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const addKey = `${ADD_EVENT}-${file}`;
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if (type === CHANGE_EVENT && this.changeTimers[addKey]) {
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// Ignore the change event that is immediately fired after an add event.
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// (This happens on Linux).
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return;
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}
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clearTimeout(this.changeTimers[key]);
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this.changeTimers[key] = setTimeout(() => {
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delete this.changeTimers[key];
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if (type === ADD_EVENT && stat.isDirectory()) {
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// Recursively emit add events and watch for sub-files/folders
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common.recReaddir(
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path.resolve(this.root, file),
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function emitAddDir(dir, stats) {
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this.watchdir(dir);
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this.rawEmitEvent(ADD_EVENT, path.relative(this.root, dir), stats);
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}.bind(this),
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function emitAddFile(file, stats) {
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this.register(file);
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this.rawEmitEvent(ADD_EVENT, path.relative(this.root, file), stats);
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}.bind(this),
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function endCallback() {},
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this.checkedEmitError,
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this.ignored
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);
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} else {
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this.rawEmitEvent(type, file, stat);
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}
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}, DEFAULT_DELAY);
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}
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/**
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* Actually emit the events
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*/
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rawEmitEvent(type, file, stat) {
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this.emit(type, file, this.root, stat);
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this.emit(ALL_EVENT, type, file, this.root, stat);
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}
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};
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/**
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* Determine if a given FS error can be ignored
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*
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* @private
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*/
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function isIgnorableFileError(error) {
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return (
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error.code === 'ENOENT' ||
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// Workaround Windows node issue #4337.
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(error.code === 'EPERM' && platform === 'win32')
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);
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}
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