WP gallery excerpt, taking *hidden* images into account

functions.php

<?php
// Check a Post for shortcode Galllery
function gallery_shortcode_exists(){
 
    global $post;
 
    # Check the content for an instance of [gallery] with or without arguments
   $pattern = get_shortcode_regex();
    if(
        preg_match_all( '/'. $pattern .'/s', $post->post_content, $matches )
        && array_key_exists( 2, $matches )
        && in_array( 'gallery', $matches[2] )
    )
        return true;
 
    # Sourced from http://codex.wordpress.org/Function_Reference/get_shortcode_regex
}

// Add Gallery Shortcode Option to Hide Images by id, from all but Admin
add_shortcode('gallery', 'custom_gallery_function');
function custom_gallery_function($atts) {
        $user = wp_get_current_user();
               
         // if current user isn't admin, add posts to be hidden to exclude
        if(!in_array('administrator', $user->roles))
        $atts['exclude'] = $atts['exclude'] . ',' . $atts['hide'];
               
    // call the wordpress shortcode function
    return gallery_shortcode($atts);
}
?>

loop.php

<?php if( ( is_category() || is_archive() || is_home() ) && gallery_shortcode_exists() ) { ?>
<?php # Determine if the post_content column contains the string [gallery]
# Grab the list of "hide" attribute
   $regex_pattern = get_shortcode_regex();
    preg_match ('/'.$regex_pattern.'/s', $post->post_content, $regex_matches);
    if ($regex_matches[2] == 'gallery') :
        $attribureStr = str_replace (" ", "&", trim ($regex_matches[3]));
        $attribureStr = str_replace ('"', '', $attribureStr);
    //  Parse the attributes
        $defaults = array (
            'hide' => '1',
        );
        $attributes = wp_parse_args ($attribureStr, $defaults);
        if (isset ($attributes["hide"])) :
            $excludeID = get_post_thumbnail_id() . ',' . $attributes["hide"];
        else :
            $excludeID = get_post_thumbnail_id();
        endif;
    endif;
# Get the first three attachments using the posts_per_page parameter
   $args = array(
        'post_type' => 'attachment',
        'post_mime_type' => 'image',
        'order'=> 'ASC',
        'posts_per_page' => 3,
        'post_parent' => get_the_ID(),
        'exclude'     => $excludeID
    );
    $attachments = get_children( $args );
    $count = count( $attachments );
# If any attachments are returned, proceed
   if( $attachments ){
# Spin cycle to collate attachment IDs
       foreach( $attachments as $attachment )
            $includes[] = $attachment->ID;
# Format our IDs in a comma-delimited string
           $includes = implode(',', $includes);
# Inject your include argument
           $shortcode = "[gallery include='$includes' link='file']"; ?>
<?php  # Render the Gallery using the standard editorial input syntax
   echo do_shortcode($shortcode);    // echo do_shortcode($shortcode);
 
# Add a View More link
   if( $count>=3 ){ ?>
        <h3 class="ribbon"><?php echo '<a href="' . get_permalink() . '">' . __('View more', 'standard') . '</a>'; ?> </h3>
    <?php } ?>
<?php }
else
     _e('No attachments found and no excerpt to display', 'standard');  ?>
<?php } else { ?>
<?php the_content( __( 'Continue Reading...', 'standard' ) ); ?>
<?php } // end if/else
?>