pagination.py

def split_pages(currentpage, totalpages):
    """
    Splits a certain number of pages into several
    lists; for example, if the current page is 31 on a total of 115
    pages the return tuple is: 
    
    ([1, 2, 3, 4], [27, 28, 29, 30, 31, 32, 33, 34], [112, 113, 114, 115])
    """
    # Check if currentpage is less than the total
    if currentpage > totalpages:
        raise NameError('The actual page value {0} is more than {1}.'.format(currentpage, totalpages))

    # Creates an ordered list of *totalpages* dimension
    pag = [number+1 for number in range(totalpages)]

    # If the total size is less than 18 then there's no need to split
    if len(pag) < 18:
        return pag
    else:
        if (currentpage in pag[:10]):
            return (pag[:currentpage+3], pag[len(pag)-4:])
        elif (currentpage in pag[len(pag)-9:]):
            return pag[:4], pag[currentpage-5:]
        else:
            return pag[:4],pag[currentpage-5:currentpage+3], pag[len(pag)-4:]


def unpack_pages(pages):
    """
    Turns a tuple of several lists obtained from the split_pages function 
    (see above) into a plain list;

    for example, the following tuple:

    ([1, 2, 3, 4], [27, 28, 29, 30, 31, 32, 33, 34], [112, 113, 114, 115])

    returns this list:

    [1, 2, 3, 4, '...', 27, 28, 29, 30, 31, 32, 33, 34, '...', 112, 113, 114, 115]
    """
    # Duck Typing: If it is a plain tuple there's no need to unpack
    try:
        pages[0][0]
    except TypeError:
        return pages

    plainlist = []
    for page in pages:
        for item in page:
            plainlist.append(item)
        if item != pages[-1][-1]: plainlist.append("...")
    return plainlist