nvim: autoload/ftplugin: git: Add helper for format-patch

nvim/.config/nvim/after/ftplugin/git.vim

@@ -5,6 +5,8 @@ nnoremap <buffer> <Leader>gB :call git#git_branch_delete()<CR>
 nnoremap <buffer> <Leader>gc :call git#git_cherry_pick()<CR>
 xnoremap <buffer> <Leader>gC :<C-U>call git#git_cherry_pick_range()<CR>
 nnoremap <buffer> <Leader>gd :call git#git_diff_commit()<CR>
+nnoremap <buffer> <Leader>gf :call git#git_format_patch()<CR>
+xnoremap <buffer> <Leader>gf :call git#git_format_patch_range()<CR>
 nnoremap <buffer> <Leader>gl :call git#git_branch_log()<CR>
 nnoremap <buffer> <Leader>gL :call git#git_branch_log_pretty()<CR>
 nnoremap <buffer> <Leader>gr :call git#git_rebase_branch()<CR>

nvim/.config/nvim/autoload/git.vim

@@ -110,6 +110,29 @@ function! git#git_diff_commit() abort
   execute "Git difftool -y " . commit[1] . " " . commit[1] . "~1"
 endfunction
 
+" To be used after running some variation of Git log.
+function! git#git_format_patch() abort
+  " A line in Git log is of the form commit <SHA>
+  let line = trim(getline('.'))
+  let commit = split(line, " ")
+  execute "Git format-patch " . commit[1] . "~1"
+endfunction
+
+" Git format-patch a range of commits. To be run on output of Git log
+" --pretty=oneline. See git_branch_log_pretty.
+function! git#git_format_patch_range() abort
+  let [lnum1, col1] = getpos("'<")[1:2]
+  let [lnum2, col2] = getpos("'>")[1:2]
+  let lines = reverse(getline(lnum1, lnum2))
+  if len(lines) == 0
+    return ''
+  endif
+  let oldCommit = split(lines[0], " ")[:0][0]
+  let newCommit = split(lines[-1], " ")[:0][0]
+  execute "Git format-patch " . oldCommit . "~1.." . newCommit
+  silent execute "bw"
+endfunction
+
 " The next two functions allow scoping diffs by line range of a file and named
 " block in a file. Inspired by reading the following article.
 " https://susanpotter.net/software/tracking-diffs-by-scoping-to-file-range-function-method-or-class-changes-in-git/