title: how to automatically generate tags from a article, base on a tag list?
body: <p>when user write a article, i wanna automatically generate tags from user writes base on a existing tag list.</p>
  
  <p>for example, i got a list like:</p>
  
  <p>Manhattan
  Brooklyn
  Queens
  ....</p>
  
  <p>if user write a article which contains these key words, it will come to the tags.</p>
  
  <p>like user have title :"Today i skated in Manhattan", then Manhattan should be include tags.</p>
  
  <p>i had considered foreach the tag list, but it is very slow if the tag list come to a big size.</p>
  
  <p>Do you guys have any solutions to automatically generate tags? or have any idea to implement this problem ?</p>
  
  <p>thanks in advance.</p>