Sort every few lines

Question

I want to sort the following based on their keys

case IndexError:
    PyErr_SetString(PyExc_IndexError, exc.str.c_str());
    break;
case ValueError:
    PyErr_SetString(PyExc_ValueError, exc.str.c_str());
    break;
case RuntimeError:
    PyErr_SetString(PyExc_RuntimeError, exc.str.c_str());
    break;
case IOError:
    PyErr_SetString(PyExc_IOError, exc.str.c_str());
    break;

so it becomes

case IOError:
    PyErr_SetString(PyExc_IOError, exc.str.c_str());
    break;
case IndexError:
    PyErr_SetString(PyExc_IndexError, exc.str.c_str());
    break;
case RuntimeError:
    PyErr_SetString(PyExc_RuntimeError, exc.str.c_str());
    break;
case ValueError:
    PyErr_SetString(PyExc_ValueError, exc.str.c_str());
    break;

Essentially, I am only sorting the lines

case IOError:
case IndexError:
case RuntimeError:
case ValueError:

The contents of the other lines (the ones that do not begin with a case) do not matter but I want them to be sorted with the cases.

Answer 1

The easy way: join the lines in the logical blocks before sorting.

In detail:

• mark the lines
• join the indented lines to the lines above: :'<,'>s/\n /^A/
• mark the lines again: gv
• sort them: :'<,'>sort
• mark the lines one more time: gv
• split the lines back and restore indentation: :'<,'>s/^A/\r /g

^A above is the character Ctrl-A (ASCII SOH). It could be any character that doesn't appear in the lines to be sorted, but Ctrl-A fits the bill. You can enter it as Ctrl-vCtrl-a.

Answer 2

Idea: Let's join the n number of lines under case to a single line. Follow the process for all cases. Then, use sort to sort the cases. Then, cut those lines back and indent them.

Steps:

1) Join n lines following case by typing this. (in your case, n is 3)

:g/case / normal! 3gJ

2) Select all such cases using visual mode. Press v ot V to select all cases. Press :. It will appear like :'<,'>. Type sort.

:'<,'>sort

3) Put the lines of case under it. Select them again by pressing gv.

:'<,'>s/\(;\|:\)    /&\r    /g

This splits the case lines. If lines arent indented properly, you can align them by selecting gv and then ==.

This works for any number of lines, provided that you use the steps customised for your purpose.