Search Form with logical

// Search Form
add_filter('get_search_form', 'philosophy_search_form');
function philosophy_search_form($form) {
	$homedir = home_url('/');
	$label 	= __('Search For:', 'philosophy');
	$button_label = __('Search', 'philosophy');

	$post_type =<<<PT
<input type="hidden" name="post_type" value="post">
PT;
	if(is_post_type_archive('book')) {
		$post_type =<<<PT
<input type="hidden" name="post_type" value="book">
PT;
	}

	$newform      = <<<FORM
<form role="search" method="get" class="header__search-form" action="{$homedir}">
    <label>
        <span class="hide-content">{$label}</span>

        {$post_type}
        <input type="search" class="search-field" placeholder="Type Keywords" value="" name="s" title="{$label}" autocomplete="off">
    </label>
    <input type="submit" class="search-submit" value="{$button_label}">
</form>
FORM;
	return $newform;
}