Format on save with clang-format (#4195)

autoload/SpaceVim/layers/lang/c.vim

@@ -101,6 +101,8 @@ else
 endif
 " }}}
 
+let s:format_on_save = 0
+
 " Load the APIs{{{
 let s:SYSTEM = SpaceVim#api#import('system')
 let s:CPT = SpaceVim#api#import('vim#compatible')
@@ -200,6 +202,26 @@ function! SpaceVim#layers#lang#c#config() abort
   else
     let s:highlight_cmd = 'ClighterEnable'
   endif
+
+  " Format on save
+  if s:format_on_save
+    call SpaceVim#layers#format#add_filetype({
+          \ 'filetype' : 'c',
+          \ 'enable' : 1,
+          \ })
+    call SpaceVim#layers#format#add_filetype({
+          \ 'filetype' : 'cpp',
+          \ 'enable' : 1,
+          \ })
+    call SpaceVim#layers#format#add_filetype({
+          \ 'filetype' : 'objc',
+          \ 'enable' : 1,
+          \ })
+    call SpaceVim#layers#format#add_filetype({
+          \ 'filetype' : 'objcpp',
+          \ 'enable' : 1,
+          \ })
+  endif
 endfunction
 " }}}
 
@@ -246,6 +268,10 @@ function! SpaceVim#layers#lang#c#set_variable(var) abort
 
   let s:enable_clang_syntax = get(a:var, 'enable_clang_syntax_highlight', s:enable_clang_syntax)
 
+  let s:format_on_save = get(a:var,
+        \ 'format_on_save',
+        \ s:format_on_save)
+
   call extend(s:clang_std, get(a:var, 'clang_std', {}))
 endfunction
 " }}}

docs/layers/lang/c.md

@@ -92,6 +92,14 @@ defined in `.clang` file. For example:
 Note: If `.clang` file contains std configuration, it will override
 `clang_std` layer option.
 
+`format_on_save`: Enable/disable file formatting when saving current file. By default,
+it is disabled, to enable it:
+```toml
+[[layers]]
+    name = 'lang#c'
+    format_on_save = true
+  ```
+
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