Revert "a refactoring for command checking"

This reverts commit 009df09.

Conflicts:
	plugin/clang_format.vim

Author: rhysd

autoload/clang_format.vim

@@ -76,23 +76,32 @@ function! clang_format#get_version()
     endtry
 endfunction
 
-function! clang_format#check_cmd()
+function! clang_format#is_invalid()
     if !exists('s:command_available')
         if ! executable(g:clang_format#command)
-            return 'clang-format is not found. check g:clang_format#command.'
+            return 1
         endif
         let s:command_available = 1
     endif
 
     if !exists('s:version')
         let v = clang_format#get_version()
         if v[0] < 3 || (v[0] == 3 && v[1] < 4)
-            return 'clang-format 3.3 or earlier is not supported for the lack of aruguments.'
+            return 2
         endif
         let s:version = v
     endif
 
-    return ''
+    return 0
+endfunction
+
+function! s:verify_command()
+    let invalidity = clang_format#is_invalid()
+    if invalidity == 1
+        echoerr "clang-format is not found. check g:clang_format#command."
+    elseif invalidity == 2
+        echoerr 'clang-format 3.3 or earlier is not supported for the lack of aruguments'
+    endif
 endfunction
 " }}}
 
@@ -145,10 +154,7 @@ endfunction
 " replace buffer {{{
 function! clang_format#replace(line1, line2)
 
-    let err_msg = clang_format#check_cmd()
-    if err_msg !=# ''
-        echoerr err_msg
-    endif
+    call s:verify_command()
 
     let pos_save = getpos('.')
     let sel_save = &l:selection

plugin/clang_format.vim

@@ -14,9 +14,9 @@ command! -range=% -nargs=0 ClangFormatEchoFormattedCode echo clang_format#format
 
 augroup plugin-clang-format-auto-format
     autocmd!
-    autocmd BufWritePre * if &ft =~# '^\%(c\|cpp\|objc\)$' && g:clang_format#auto_format && clang_format#check_cmd() ==# '' | call clang_format#replace(1, line('$')) | endif
-    autocmd FileType c,cpp,objc if g:clang_format#auto_format_on_insert_leave && clang_format#check_cmd() ==# '' | call clang_format#enable_format_on_insert() | endif
-    autocmd FileType c,cpp,objc if g:clang_format#auto_formatexpr && clang_format#check_cmd() ==# '' | setlocal formatexpr=clang_format#replace(v:lnum,v:lnum+v:count-1) | endif
+    autocmd BufWritePre * if &ft =~# '^\%(c\|cpp\|objc\)$' && g:clang_format#auto_format && !clang_format#is_invalid() | call clang_format#replace(1, line('$')) | endif
+    autocmd FileType c,cpp,objc if g:clang_format#auto_format_on_insert_leave && !clang_format#is_invalid() | call clang_format#enable_format_on_insert() | endif
+    autocmd FileType c,cpp,objc if g:clang_format#auto_formatexpr && !clang_format#is_invalid() | setlocal formatexpr=clang_format#replace(v:lnum,v:lnum+v:count-1) | endif
 augroup END
 
 let g:loaded_clang_format = 1