<?php
namespace eMacros\Runtime\Collection;
use eMacros\Runtime\GenericFunction;
class Car extends GenericFunction {
/**
* Returns the head element on a list
* Usage: (Array:car (array 1 2 3))
* Returns: mixed
* (non-PHPdoc)
* @see \eMacros\Runtime\GenericFunction::execute()
*/
public function execute(array $arguments) {
if (empty($arguments)) {
throw new \BadFunctionCallException("Car: No parameters found.");
}
list($list) = $arguments;
if ($list instanceof \Iterator) {
$list->rewind();
$value = $list->valid() ? $list->current() : null;
}
elseif ($list instanceof \IteratorAggregate) {
$iter = $list->getIterator();
$iter->rewind();
$value = $iter->valid() ? $iter->current() : null;
}
elseif (is_array($list)) {
$value = !empty($list) ? array_shift($list) : null;
}
elseif ($list instanceof \ArrayAccess) {
//cannot ensure which is the first element, return index 0
$value = isset($list[0]) ? $list[0] : null;
}
else {
throw new \InvalidArgumentException('Car: Parameter is not a list.');
}
return $value;
}
}
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