Web Browser Bookmarking in Python

An essential feature of any modern web browser is the ability to bookmark your favorite websites so you can quickly revisit them later. Here, we'll be creating a basic bookmark service that will implement commands for bookmarking the currently visited URL, as well as the ability to undo and redo actions.

Web Browser:

class WebBrowser(object):
   def __init__(self):
       self.bookmarks = []
       self.currentUrl = None
   
   def Navigate(self, url):
       self.currentUrl = url
   
   def BookmarkCurrentPage(self):
       valid = self.currentUrl is not None
       contains = self.currentUrl in self.bookmarks
       if valid and not contains:
           self.bookmarks.append(self.currentUrl)

   def RemoveBookmark(self, url):
       self.bookmarks.remove(url)
   
   def PrintBookmarks(self):
       print("Bookmarks:")
       for i in self.bookmarks:
           print("\t"+ str(i))

AddBookmarkCommand:

class AddBookmarkCommand(object):
   def __init__(self, webBrowser):
       self.webBrowser = webBrowser
       self.url = None

   def Execute(self):
       self.url = self.webBrowser.currentUrl
       self.webBrowser.BookmarkCurrentPage()

   def Undo(self):
       self.webBrowser.RemoveBookmark(self.url)

   def Redo(self):
       self.Execute()

With the bookmark command, we'll create our Bookmarker that will hold two stacks for the undo and redo commands.

Bookmarker:

class Bookmarker(object):
   def __init__(self, webBrowser):
       self.webBrowser = webBrowser
       self.undoStack = []
       self.redoStack = []

   def BookmarkCurrentPage(self):
       command = AddBookmarkCommand(self.webBrowser)
       self.undoStack.append(command)
       self.redoStack = []

       command.Execute()

   def UndoBookmark(self):
       if len(self.undoStack) != 0:
           command = self.undoStack.pop()
           self.redoStack.append(command)

           command.Undo()

   def RedoBookmark(self):
       if len(self.redoStack) != 0:
           command = self.redoStack.pop()
           self.undoStack.append(command)

           command.Redo()

Demo:

memeSurfer = WebBrowser()
bookmarker = Bookmarker(memeSurfer)

memeSurfer.Navigate("dankMemes.gov")
bookmarker.BookmarkCurrentPage()

memeSurfer.PrintBookmarks()

memeSurfer.Navigate("normieMemes.co")
bookmarker.BookmarkCurrentPage()

memeSurfer.PrintBookmarks()

bookmarker.UndoBookmark()

memeSurfer.PrintBookmarks()

bookmarker.RedoBookmark()

memeSurfer.PrintBookmarks()