/**
* Selects one among a number of possible alternatives.
*
* <pre>
* <!-- Category: instruction -->
* <p:choose>
* <!-- Content: (p:when+, p:otherwise?) -->
* </p:choose>
*
* <p:when
* test = boolean-expression>
* <!-- Content: template -->
* </p:when>
*
* <p:otherwise>
* <!-- Content: template -->
* </p:otherwise>
* </pre>
*
* It consists of a sequence of `p:when` elements followed by an optional `p:otherwise`
* element. Each `p:when` element has a single attribute, test, which specifies an expression.
* The content of the `p:when` and `p:otherwise` elements is a template. When an `p:choose`
* element is processed, each of the `p:when` elements is tested in turn, by evaluating the
* expression and converting the resulting object to a boolean as if by a call to the boolean
* function. The content of the first, and only the first, `p:when` element whose test is true
* is instantiated. If no `p:when` is true, the content of the `p:otherwise` element is
* instantiated. If no `p:when` element is true, and no `p:otherwise` element is present,
* nothing is created.
*
* @param array $args
* @param Engine $patron
* @param mixed $template
*
* @return string
*/
public static function markup_choose(array $args, Engine $patron, $template)
{
$otherwise = null;
#
# handle 'when' children as they are defined.
# if we find an 'otherwise' we keep it for later
#
foreach ($template as $node) {
$name = $node->name;
if ($name == 'otherwise') {
$otherwise = $node;
continue;
}
if ($name != 'when') {
$patron->error('Unexpected child: :node', [':node' => $node]);
return null;
}
$value = $patron->evaluate($node->args['test'], true);
if ($value) {
return $patron($node->nodes);
}
}
#
# otherwise
#
if (!$otherwise) {
return null;
}
return $patron($otherwise->nodes);
}
