text: // Copyright 2012 The Go Authors. All rights reserved.
  // Use of this source code is governed by a BSD-style
  // license that can be found in the LICENSE file.
  
  // Package fsnotify implements file system notification.
  package fsnotify
  
  import "fmt"
  
  const (
  	FSN_CREATE = 1
  	FSN_MODIFY = 2
  	FSN_DELETE = 4
  	FSN_RENAME = 8
  
  	FSN_ALL = FSN_MODIFY | FSN_DELETE | FSN_RENAME | FSN_CREATE
  )
  
  // Purge events from interal chan to external chan if passes filter
  func (w *Watcher) purgeEvents() {
  	for ev := range w.internalEvent {
  		sendEvent := false
  		w.fsnmut.Lock()
  		fsnFlags := w.fsnFlags[ev.Name]
  		w.fsnmut.Unlock()
  
  		if (fsnFlags&FSN_CREATE == FSN_CREATE) && ev.IsCreate() {
  			sendEvent = true
  		}
  
  		if (fsnFlags&FSN_MODIFY == FSN_MODIFY) && ev.IsModify() {
  			sendEvent = true
  		}
  
  		if (fsnFlags&FSN_DELETE == FSN_DELETE) && ev.IsDelete() {
  			sendEvent = true
  		}
  
  		if (fsnFlags&FSN_RENAME == FSN_RENAME) && ev.IsRename() {
  			sendEvent = true
  		}
  
  		if sendEvent {
  			w.Event <- ev
  		}
  
  		// If there's no file, then no more events for user
  		// BSD must keep watch for internal use (watches DELETEs to keep track
  		// what files exist for create events)
  		if ev.IsDelete() {
  			w.fsnmut.Lock()
  			delete(w.fsnFlags, ev.Name)
  			w.fsnmut.Unlock()
  		}
  	}
  
  	close(w.Event)
  }
  
  // Watch a given file path
  func (w *Watcher) Watch(path string) error {
  	return w.WatchFlags(path, FSN_ALL)
  }
  
  // Watch a given file path for a particular set of notifications (FSN_MODIFY etc.)
  func (w *Watcher) WatchFlags(path string, flags uint32) error {
  	w.fsnmut.Lock()
  	w.fsnFlags[path] = flags
  	w.fsnmut.Unlock()
  	return w.watch(path)
  }
  
  // Remove a watch on a file
  func (w *Watcher) RemoveWatch(path string) error {
  	w.fsnmut.Lock()
  	delete(w.fsnFlags, path)
  	w.fsnmut.Unlock()
  	return w.removeWatch(path)
  }
  
  // String formats the event e in the form
  // "filename: DELETE|MODIFY|..."
  func (e *FileEvent) String() string {
  	var events string = ""
  
  	if e.IsCreate() {
  		events += "|" + "CREATE"
  	}
  
  	if e.IsDelete() {
  		events += "|" + "DELETE"
  	}
  
  	if e.IsModify() {
  		events += "|" + "MODIFY"
  	}
  
  	if e.IsRename() {
  		events += "|" + "RENAME"
  	}
  
  	if e.IsAttrib() {
  		events += "|" + "ATTRIB"
  	}
  
  	if len(events) > 0 {
  		events = events[1:]
  	}
  
  	return fmt.Sprintf("%q: %s", e.Name, events)
  }
  