title: Generate AST of a PHP source file
body: <p>I want to parse a PHP source file, into an AST (preferably as a nested array of instructions).</p>
  
  <p>I basically want to convert things like</p>
  
  <pre><code>f($a, $b + 1)
  </code></pre>
  
  <p>into something like</p>
  
  <pre><code>array( 'function_call',
      array(
          array( 'var', '$a' ),
          array( 'expression',
              array(
                  array( 'binary_operation',
                      '+',
                      array ('var', '$b'),
                      array( 'int', '1' )
                  )
              )
          )
      )
  )
  </code></pre>
  
  <p>Are there any inbuilt PHP library or third party libraries (preferably in PHP) that would let me do this?</p>