GitLogViewer inspired by ujihisa's vimrc

gitlogviewer.vim

" Inspired by ujihisa's vimrc
function! s:GitLogViewer()
  " vnewだとコミットメッセージが切れてしまうのでnew
  new
  VimProcRead git log -u 'ORIG_HEAD..HEAD'
  set filetype=git-log.git-diff
  setlocal foldmethod=expr
  setlocal foldexpr=getline(v:lnum)=~'^commit'?'>1':getline(v:lnum+1)=~'^commit'?'<1':'='
  setlocal foldtext=FoldTextOfGitLog()
endfunction
command! GitLogViewer call s:GitLogViewer()

" git log表示時の折りたたみ用
function! FoldTextOfGitLog()
  let month_map = {
    \ 'Jan' : '01',
    \ 'Feb' : '02',
    \ 'Mar' : '03',
    \ 'Apr' : '04',
    \ 'May' : '05',
    \ 'Jun' : '06',
    \ 'Jul' : '07',
    \ 'Aug' : '08',
    \ 'Sep' : '09',
    \ 'Oct' : '10',
    \ 'Nov' : '11',
    \ 'Dec' : '12',
    \ }

  if getline(v:foldstart) !~ '^commit'
    return getline(v:foldstart)
  endif

  if getline(v:foldstart + 1) =~ '^Author:'
    let author_lnum = v:foldstart + 1
  elseif getline(v:foldstart + 2) =~ '^Author:'
    " commitの次の行がMerge:の場合があるので
    let author_lnum = v:foldstart + 2
  else
    " commitの下2行がどちらもAuthor:で始まらなければ諦めて終了
    return getline(v:foldstart)
  endif

  let date_lnum = author_lnum + 1
  let message_lnum = date_lnum + 2

  let author = matchstr(getline(author_lnum), '^Author: \zs.*\ze <.\{-}>')
  let date = matchlist(getline(date_lnum), ' \(\a\{3}\) \(\d\{1,2}\) \(\d\{2}:\d\{2}:\d\{2}\) \(\d\{4}\)')
  let message = getline(message_lnum)

  let month = date[1]
  let day = printf('%02s', date[2])
  let time = date[3]
  let year = date[4]

  let datestr = join([year, month_map[month], day], '-')

  return join([datestr, time, author, message], ' ')
endfunction