In Vim, command to open a filename under the cursor in a new Vim tab (or if URL, open in browser)

open_filename_in_tab.vim

if has('python') " Assumes Python >= 2.6

    " Quick way to open a filename under the cursor in a new tab
    " (or URL in a browser)
    function! Open()
python <<EOF
import re
import platform
import vim

def launch(uri):
    if platform.system() == 'Darwin':
        vim.command('!open {0}'.format(uri))
    elif platform.system() == 'Linux':
        vim.command('!gnome-open {0}'.format(uri))

def is_word(text):
    return re.match(r'^[\w./?%:#&=-]+$', text) is not None

filename_start = filename_end = vim.current.window.cursor[1] # (row, col)

while filename_start >= 0 and is_word(vim.current.line[filename_start:filename_start+1]):
    filename_start -= 1
filename_start += 1

while filename_end <= len(vim.current.line) and is_word(vim.current.line[filename_end:filename_end+1]):
    filename_end += 1

filename = vim.current.line[filename_start:filename_end]

if filename.endswith('.rst') or filename.endswith('.txt'):
    vim.command('tabedit {0}'.format(filename))

elif filename.lower().startswith('http') or filename.lower().startswith('www.'):
    if filename.lower().startswith('www.'):
        filename = 'http://{0}'.format(filename)
    filename = filename.replace('#', r'\#').replace('%', r'\%')
    launch(filename)

else:
    launch(filename)
EOF

    endfunction

    command O call Open()
    map <Leader>o :call Open()<CR>

endif " python