Yawl - Yet Another Watcher Library

yawl.js

/*
 * Yawl - Yet Another Watcher Library
 * Copyright (c) 2013 Peter Jihoon Kim. This software is licensed under the MIT License.
 */

(function() {
  "use strict";

  var fs = require('fs');
  var Path = require('path');
  var EventEmitter = require('events').EventEmitter;

  var Yawl = function(path, options) {
    this.path = path;
    this.watchers = {};
    this.changeTimeout = null;
    options = options || {};
    this.exclude = options.exclude || [];
    this.delay = options.delay || 0;
  };

  Yawl.prototype = new EventEmitter;

  Yawl.prototype.start = function() {
    this._watch(this.path);
  };

  Yawl.prototype.stop = function() {
    for (var key in this.watchers) {
      if (this.watchers.hasOwnProperty(key)) {
        this._closeWatcher(key);
      }
    }
  };

  Yawl.prototype._pathDidChange = function(path) {
    var self = this;
    if (self.watchers[path]) {
      fs.lstat(path, function(err, stats) {
        if (err) {
          self._unwatch(path);
          return;
        }
        self._watch(path);
      });
    }
    if (this.changeTimeout === null) {
      this.changeTimeout = setTimeout(function() {
        self.changeTimeout = null;
        self.emit('change');
      }, this.delay);
    }
  };

  Yawl.prototype._watch = function(path) {
    var self = this;
    if (self.exclude.indexOf(path) !== -1) {
      return;
    }
    self._unwatch(path);
    fs.lstat(path, function(err, stats) {
      if (err) {
        return;
      } else if (stats.isDirectory()) {
        fs.readdir(path, function(err, files) {
          for (var i in files) {
            var subPath = Path.join(path, files[i]);
            self._watch(subPath);
          }
        });
      }
      try {
        self.watchers[path] = fs.watch(path, function() {
          self._pathDidChange(path);
        });
      } catch (e) {
        self._unwatch(path);
      }
    });
  };

  Yawl.prototype._closeWatcher = function(path) {
    var watcher = this.watchers[path];
    if (watcher) {
      watcher.close();
      this.watchers[path] = undefined;
    }
  }

  Yawl.prototype._unwatch = function(path) {
    this._closeWatcher(path);
    var pathWithSep = path + Path.sep;
    for (var key in this.watchers) {
      if (key.indexOf(pathWithSep) === 0) {
        this._closeWatcher(key);
      }
    }
  };

  module.exports = Yawl;
}).call(this);