child pages of parent menu

child_pages_menu.php

  <?php
    if( is_page() ) {

		if ( is_page() ) $q_page = $post->ID;
        
		if ( get_post_meta( $q_page, PREFIX.'_page_subpages_sidebar', true ) == 'true' ) { 		

			if ( $post->post_parent == 0 )  $parent  = $post->ID;
			else                            $parent  = $post->post_parent ; 
			
			$child_pages = get_pages('child_of='.$parent);
			
			if ($child_pages) { ?>
			
			<div class="left-menu">
				<ul>
					<?php				
					$page_link = get_permalink( $parent ); ?>
		
					<?php if ( $q_page == $parent ) { ?>
						<li class="active"><a href="<?php echo $page_link ?>"><?php echo $post->post_title; ?></a></li>
						
					<?php } else { $post = get_post($parent); ?>
						<li><a href="<?php the_permalink(); ?>"><?php the_title(); ?></a></li>
						
					<?php } ?>
					
					<?php $pages = get_pages("child_of=".$parent);  
					foreach ($pages as $page) {
						 
						if ( $q_page == $page->ID ) { ?>
							<li class="active"><a href="<?php echo get_permalink( $page->ID ) ?>"><?php echo $page->post_title; ?></a></li>
							
						<?php } else { ?>
							<li><a href="<?php echo get_permalink( $page->ID ) ?>"><?php echo $page->post_title; ?></a></li>
						<?php }                                
					}                               
					?>
				</ul>
			</div>
			
			<?php 
			}
		}
    }
    ?>