Version detection, better error handling, bug fix for dynamic highlighting

 * The plug-in now executes `ctags --version` on startup to verify that
   the correct version of Exuberant Ctags is installed because some
   systems (including Mac OS X apparently) ship with a `/usr/bin/ctags`
   installed that doesn't understand the extensive set of command-line
   arguments supported by Exuberant Ctags.

 * When a file was edited multiple times the dynamic highlighting
   wouldn't refresh because the plug-in thought the highlighting was
   still in effect while in reality it was cleared by reading the file
   again. Now the highlighting will be refreshed on the next CursorHold
   event like it's supposed to.

1 files changed, 50 insertions, 25 deletions

diff --git a/easytags.vim b/easytags.vim
index fc6ab77..30efb3d 100644
--- a/easytags.vim
+++ b/easytags.vim
@@ -1,10 +1,10 @@
 " Vim plug-in
 " Maintainer: Peter Odding <peter@peterodding.com>
-" Last Change: June 13, 2010
+" Last Change: June 15, 2010
 " URL: http://peterodding.com/code/vim/easytags
 " Requires: Exuberant Ctags (http://ctags.sf.net)
 " License: MIT
-" Version: 1.9
+" Version: 1.9.3
 
 " Support for automatic update using the GLVS plug-in.
 " GetLatestVimScripts: 3114 1 :AutoInstall: easytags.zip
@@ -40,38 +40,62 @@ if !exists('g:easytags_ignored_filetypes')
   let g:easytags_ignored_filetypes = '^tex$'
 endif
 
-" Before sourcing the rest of the plug-in first check that the location of the
-" "Exuberant Ctags" program has been configured or that the program exists in
-" one of its default locations.
-
-if exists('g:easytags_cmd') && executable(g:easytags_cmd)
-  let s:ctags_installed = 1
-else
+function! s:InitEasyTags(version)
+  " Check that the location of Exuberant Ctags has been configured or that the
+  " correct version of the program exists in one of its default locations.
+  if exists('g:easytags_cmd') && s:CheckCtags(g:easytags_cmd, a:version)
+    return 1
+  endif
   " On Ubuntu Linux, Exuberant Ctags is installed as `ctags'. On Debian Linux,
   " Exuberant Ctags is installed as `exuberant-ctags'. On Free-BSD, Exuberant
   " Ctags is installed as `exctags'. Finally there is `ctags.exe' on Windows.
-  for s:command in ['ctags', 'exuberant-ctags', 'esctags', 'ctags.exe']
-    if executable(s:command)
-      let g:easytags_cmd = s:command
-      let s:ctags_installed = 1
-      break
+  for name in ['ctags', 'exuberant-ctags', 'esctags']
+    if s:CheckCtags(name, a:version)
+      let g:easytags_cmd = name
+      return 1
     endif
   endfor
-  unlet s:command
-endif
-
-if !exists('s:ctags_installed')
-  echomsg "easytags.vim: Exuberant Ctags unavailable! Plug-in not loaded."
-  if executable('apt-get')
-    echomsg "On Ubuntu & Debian Linux, you can install Exuberant Ctags"
-    echomsg "by installing the package named `exuberant-ctags':"
-    echomsg "  sudo apt-get install exuberant-ctags"
+endfunction
+
+function! s:CheckCtags(name, version)
+  " Not every executable out there named `ctags' is in fact Exuberant Ctags.
+  " This function makes sure it is because the easytags plug-in requires the
+  " --list-languages option.
+  if executable(a:name)
+    let listing = system(a:name . ' --version')
+    let pattern = 'Exuberant Ctags \zs\d\+\(\.\d\+\)*'
+    let g:easytags_ctags_version = matchstr(listing, pattern)
+    return s:VersionToNumber(g:easytags_ctags_version) >= a:version
+  endif
+endfunction
+
+function! s:VersionToNumber(s)
+  let values = split(a:s, '\.')
+  if len(values) == 1
+    return values[0] * 10
+  elseif len(values) >= 2
+    return values[0] * 10 + values[1][0]
+  endif
+endfunction
+
+if !s:InitEasyTags(55)
+  if !exists('g:easytags_ctags_version') || empty(g:easytags_ctags_version)
+    let msg = "easytags.vim: Plug-in not loaded because Exuberant Ctags isn't installed!"
+    if executable('apt-get')
+      let msg ,= " On Ubuntu & Debian you can install Exuberant Ctags by"
+      let msg .= " installing the package named `exuberant-ctags':"
+      let msg .= " sudo apt-get install exuberant-ctags"
+    else
+      let msg .= " Please download & install Exuberant Ctags from http://ctags.sf.net"
+    endif
+    echomsg msg
   else
-    echomsg "Please download & install Exuberant Ctags from http://ctags.sf.net"
+    let msg = "easytags.vim: Plug-in not loaded because Exuberant Ctags 5.5"
+    let msg .= " or newer is required while you have version %s installed!"
+    echomsg printf(msg, g:easytags_ctags_version)
   endif
   finish
 endif
-unlet s:ctags_installed
 
 " Let Vim know about the global tags file created by this plug-in.
 
@@ -106,6 +130,7 @@ augroup PluginEasyTags
   endif
   if g:easytags_on_cursorhold
     autocmd CursorHold,CursorHoldI * call easytags#autoload()
+    autocmd BufReadPost * unlet! b:easytags_last_highlighted
   endif
   autocmd User PublishPre HighlightTags
 augroup END