tabline: prepare for vim9script implementation

autoload/airline/extensions/tabline.vim

@@ -11,7 +11,10 @@ endif
 let s:ctrlspace = get(g:, 'CtrlSpaceLoaded', 0)
 let s:tabws = get(g:, 'tabws_loaded', 0)
 
-function! airline#extensions#tabline#init(ext)
+unlet! g:airline_experimental
+if !exists(":def") || (exists(":def") && get(g:, "airline_experimental", 0)==0)
+
+  function! airline#extensions#tabline#init(ext)
     if has('gui_running')
       set guioptions-=e
     endif
@@ -21,9 +24,9 @@ function! airline#extensions#tabline#init(ext)
 
     call s:toggle_on()
     call a:ext.add_theme_func('airline#extensions#tabline#load_theme')
-endfunction
+  endfunction
 
-function! s:toggle_off()
+  function! s:toggle_off()
     call airline#extensions#tabline#autoshow#off()
     call airline#extensions#tabline#tabs#off()
     call airline#extensions#tabline#buffers#off()
@@ -33,9 +36,9 @@ function! s:toggle_off()
     if s:tabws
       call airline#extensions#tabline#tabws#off()
     endif
-endfunction
+  endfunction
 
-function! s:toggle_on()
+  function! s:toggle_on()
     if get(g:, 'airline_statusline_ontop', 0)
       call airline#extensions#tabline#enable()
       let &tabline='%!airline#statusline('.winnr().')'
@@ -52,9 +55,9 @@ function! s:toggle_on()
     endif
 
     set tabline=%!airline#extensions#tabline#get()
-endfunction
+  endfunction
 
-function! s:update_tabline(forceit)
+  function! s:update_tabline(forceit)
     if get(g:, 'airline#extensions#tabline#disable_refresh', 0)
       return
     endif
@@ -74,9 +77,9 @@ function! s:update_tabline(forceit)
     endif
     call airline#util#doautocmd('BufMRUChange')
     call airline#extensions#tabline#redraw()
-endfunction
+  endfunction
 
-function! airline#extensions#tabline#redraw()
+  function! airline#extensions#tabline#redraw()
     " sometimes, the tabline is not correctly updated see #1580
     " so force redraw here
     if exists(":redrawtabline") == 2
@@ -87,15 +90,15 @@ function! airline#extensions#tabline#redraw()
     " need something less invasive.
       let &ro = &ro
     endif
-endfunction
+  endfunction
 
-function! airline#extensions#tabline#enable()
+  function! airline#extensions#tabline#enable()
     if &lines > 3
       set showtabline=2
     endif
-endfunction
+  endfunction
 
-function! airline#extensions#tabline#load_theme(palette)
+  function! airline#extensions#tabline#load_theme(palette)
     if pumvisible()
       return
     endif
@@ -142,11 +145,11 @@ function! airline#extensions#tabline#load_theme(palette)
     call airline#highlighter#exec('airline_tabmod_right', tabmod_right)
     call airline#highlighter#exec('airline_tabhid_right', tabhid_right)
     call airline#highlighter#exec('airline_tabmod_unsel_right', tabmodu_right)
-endfunction
+  endfunction
 
-let s:current_tabcnt = -1
+  let s:current_tabcnt = -1
 
-function! airline#extensions#tabline#get()
+  function! airline#extensions#tabline#get()
     let show_buffers = get(g:, 'airline#extensions#tabline#show_buffers', 1)
     let show_tabs = get(g:, 'airline#extensions#tabline#show_tabs', 1)
 
@@ -174,9 +177,9 @@ function! airline#extensions#tabline#get()
     else
       return airline#extensions#tabline#tabs#get()
     endif
-endfunction
+  endfunction
 
-function! airline#extensions#tabline#title(n)
+  function! airline#extensions#tabline#title(n)
     let title = ''
     if s:taboo
       let title = TabooTabTitle(a:n)
@@ -203,15 +206,15 @@ function! airline#extensions#tabline#title(n)
     endif
 
     return title
-endfunction
+  endfunction
 
-function! airline#extensions#tabline#get_buffer_name(nr, ...)
+  function! airline#extensions#tabline#get_buffer_name(nr, ...)
     let buffers = a:0 ? a:1 : airline#extensions#tabline#buflist#list()
     let formatter = get(g:, 'airline#extensions#tabline#formatter', 'default')
     return airline#extensions#tabline#formatters#{formatter}#format(a:nr, buffers)
-endfunction
+  endfunction
 
-function! airline#extensions#tabline#new_builder()
+  function! airline#extensions#tabline#new_builder()
     let builder_context = {
           \ 'active'        : 1,
           \ 'tabline'       : 1,
@@ -227,9 +230,9 @@ function! airline#extensions#tabline#new_builder()
     endif
 
     return airline#extensions#tabline#builder#new(builder_context)
-endfunction
+  endfunction
 
-function! airline#extensions#tabline#group_of_bufnr(tab_bufs, bufnr)
+  function! airline#extensions#tabline#group_of_bufnr(tab_bufs, bufnr)
     let cur = bufnr('%')
     if cur == a:bufnr
       if g:airline_detect_modified && getbufvar(a:bufnr, '&modified')
@@ -247,21 +250,24 @@ function! airline#extensions#tabline#group_of_bufnr(tab_bufs, bufnr)
       endif
     endif
     return group
-endfunction
+  endfunction
 
-function! airline#extensions#tabline#add_label(dict, type, right)
+  function! airline#extensions#tabline#add_label(dict, type, right)
     if get(g:, 'airline#extensions#tabline#show_tab_type', 1)
       call a:dict.add_section_spaced('airline_tablabel'.
             \ (a:right ? '_right' : ''),
             \ get(g:, 'airline#extensions#tabline#'.a:type.'_label', a:type))
     endif
-endfunction
+  endfunction
 
-function! airline#extensions#tabline#add_tab_label(dict)
+  function! airline#extensions#tabline#add_tab_label(dict)
     let show_tab_count = get(g:, 'airline#extensions#tabline#show_tab_count', 1)
     if show_tab_count == 2
       call a:dict.add_section_spaced('airline_tabmod', printf('%s %d/%d', "tab", tabpagenr(), tabpagenr('$')))
     elseif show_tab_count == 1 && tabpagenr('$') > 1
       call a:dict.add_section_spaced('airline_tabmod', printf('%s %d/%d', "tab", tabpagenr(), tabpagenr('$')))
     endif
-endfunction
+  endfunction
+else
+  " Vim9 Script implementation
+endif