Source

File: wp-includes/formatting.php

function _wptexturize_pushpop_element( $text, &$stack, $disabled_elements ) {
	// Is it an opening tag or closing tag?
	if ( isset( $text[1] ) && '/' !== $text[1] ) {
		$opening_tag = true;
		$name_offset = 1;
	} elseif ( 0 === count( $stack ) ) {
		// Stack is empty. Just stop.
		return;
	} else {
		$opening_tag = false;
		$name_offset = 2;
	}

	// Parse out the tag name.
	$space = strpos( $text, ' ' );
	if ( false === $space ) {
		$space = -1;
	} else {
		$space -= $name_offset;
	}
	$tag = substr( $text, $name_offset, $space );

	// Handle disabled tags.
	if ( in_array( $tag, $disabled_elements, true ) ) {
		if ( $opening_tag ) {
			/*
			 * This disables texturize until we find a closing tag of our type
			 * (e.g. <pre>) even if there was invalid nesting before that.
			 *
			 * Example: in the case <pre>sadsadasd</code>"baba"</pre>
			 *          "baba" won't be texturized.
			 */

			array_push( $stack, $tag );
		} elseif ( end( $stack ) == $tag ) {
			array_pop( $stack );
		}
	}
}