" git で現在開いているファイルの前回の変更を開く。(require metarw-git)
nnoremap <silent> eg :<C-u>call <SID>git_prev_rev()<CR>
 
function! s:git_prev_rev()
	let path = expand('%')
	let commit = "HEAD"
 
	let l = matchlist(path, 'git:\([^:]\+\):\([^:]\+\)')
	if len(l) > 0
		let commit = l[1]
		let path   = l[2]
	endif
 
	let output = system(printf("git log -n 2 --pretty=format:'%%h %%s' HEAD~1000..%s -- %s",
	\                          shellescape(commit),
	\                          shellescape(path)))
 
	if v:shell_error != 0
		echoerr 'git log failed with the following reason:'
		echoerr output
		return
	endif
 
	let commits = split(output, "\n")
	let prev    = commits[1]
	let [commit_id, subject] = matchlist(prev, '^\(\S*\)\s\(.*\)$')[1:2]
 
	let cursor = getpos(".")
	silent edit `=printf('git:%s:%s', commit_id, path)`
	call setpos('.', cursor)
 
	echo subject
endfunction