<p>
  This message
  <span class="class1" title="title1" style="backgorund-color: #ffeea1; color: red; border: 1px solid green;">
    is abs. awsome
  </span>.
</p>
<p class="class2">
   Hello world
</p>

$tags = array(
  'p' => array(
    '0' => array(
      'text' => 'This message',
      'content' => array(
        'span' => array(
          '0' => array(
            'text' => 'is abs. awsome',
            'attributes' => array(
              'class' => 'class1',
              'title' => 'title1'
            ),
            'styles' => array(
              'background-color' => '#ffeea1',
              'color' => 'red',
              'border' => '1px solid green',
            )
          )
        )
      )
    ),
    '1' => array(
      'text' => 'Hello world',
      'attributes' => array(
        'class' => 'class2'
      )
    )
  )
);

function processHTML($html) {
  // some regex processing
  // return $associative_array_with_tags_attributes_and_texts
}