title: How to add conditional code in Android.bp
body: <p>AOSP now has new build system, and file <code>Android.bp</code> has replaced <code>Android.mk</code> in many places.</p>
  
  <p>Now I want to list source files conditionally depending on platform.</p>
  
  <p>Say something like this:</p>
  
  <pre><code>if(atom)
  {
     src: [
        .......list of files.......
     ],
     exclude_srcs: [
        .......list of files.......
     ]
  } else
  {
     src: [
        .......list of files.......
     ],
     exclude_srcs: [
        .......list of files.......
     ]
  }
  </code></pre>
  
  <p>Any suggestions how to achieve this?
  Also, how can I achieve logical operations like <code>NOT</code>, <code>OR</code> etc in conditionals?</p>
  
  <p>Thanks in advance.</p>