Reimplement mail header importance flagging

Just for fun, write something a little more comprehensive to read in the
entire mail header as a data structure, in order to add or set header
fields correctly.  I don't think this is totally RFC-compliant yet; I'll
need to check.

1 files changed, 54 insertions, 0 deletions

diff --git a/vim/autoload/mail/header.vim b/vim/autoload/mail/header.vim
new file mode 100644
index 00000000..8495a721
--- /dev/null
+++ b/vim/autoload/mail/header.vim
@@ -0,0 +1,54 @@
+function! mail#header#Read() abort
+  let fields = []
+  for lnum in range(1, line('$'))
+    let line = getline(lnum)
+    let matchlist = matchlist(
+          \ line,
+          \ '^\([a-zA-Z0-9-]\+\):\s*\(\_.*\)',
+          \)
+    if !empty(matchlist)
+      let field = {
+            \ 'name': matchlist[1],
+            \ 'body': matchlist[2],
+            \}
+      call add(fields, field)
+    elseif line =~ '^\s' && exists('field')
+      let field['body'] .= "\n" . line
+    elseif line ==# ''
+      break
+    else
+      throw 'Parse error'
+    endif
+  endfor
+  let header = {
+        \'fields': fields,
+        \}
+  return header
+endfunction
+
+function! mail#header#String(header) abort
+  let fields = copy(a:header['fields'])
+  return join(
+        \ map(
+          \ copy(a:header['fields']),
+          \ 'v:val[''name''] . '': '' . v:val[''body''] . "\n"'),
+        \ '',
+        \)
+endfunction
+
+function! mail#header#Write(header) abort
+  let start = 1
+  for lnum in range(1, line('$'))
+    if getline(lnum) ==# ''
+      break
+    endif
+    let end = lnum
+  endfor
+  let curpos = getpos('.')
+  if exists('end')
+    let range = join([start, end], ',')
+    execute join(['silent', range, 'delete'])
+  endif
+  silent 0 put =mail#header#String(a:header)
+  call setpos('.', curpos)
+endfunction