[Feature request] Add trailing_comma option

[gepbird]

trailing_comma option should control how trailing commas are formatted in tables. This feature would make git diffs nicer. The values could be:

• never

  t1 = { 1, 2 }
  t2 = {
  1,
  2
  }

• smart (only add it when it is the last character on a line)

  t1 = { 1, 2 }
  t2 = {
  1,
  2,
  }

• always

  t1 = { 1, 2, }
  t2 = {
  1,
  2,
  }

Personally I wouldn't use always value, but some people might find it useful.

[CppCXY]

in fact, lua allow semicolon as the end of table field. should this called 'railing_comma'?

[gepbird]

Hmm, that's intresting. If you want to include semicolons too maybe calling it trailing_separator (or trailing_table_separator?) would be better. And also having another option separator_style (or table_separator ) that has values comma and semicolon.

I don't insist on supporting semicolons for this, since I've only seen lua codebases that use commas.

[CppCXY]

ok wait one day

[CppCXY]

feature complete.

option table_separator_style support none/comma/semicolon

option trailing_table_separator support keep/never/always/smart