$variable OR $variable = $variable in PHP
<p>This is a standalone expression in a function:</p>

<pre><code>$var OR $var = $var
</code></pre>

<p>What does this expression exactly do? </p>

<p>Never saw this before and can't find the answer as I have no idea how is this called.</p>

<p>Code itself is from: <a href="https://github.com/philsturgeon/codeigniter-template/blob/master/libraries/Template.php" rel="nofollow">Сodeigniter Template on Github</a></p>

<pre><code>public function build($view, $data = array(), $return = FALSE)
{
    // Set whatever values are given. These will be available to all view files
    is_array($data) OR $data = (array) $data;
    // Merge in what we already have with the specific data
    $this-&gt;_data = array_merge($this-&gt;_data, $data);

...
</code></pre>