Add bundler.vim support

README.markdown

@@ -5,7 +5,8 @@ With rake.vim, you can use all those parts of
 [rails.vim](https://github.com/tpope/vim-rails) that you wish you could
 use on your other Ruby projects on anything with a `Rakefile`, including
 `:R`/`:A`, `:Rlib` and friends, and of course `:Rake`.  It's great when
-paired with `gem open` and `bundle open`.
+paired with `gem open` and `bundle open` and complemented nicely by
+[bundler.vim](https://github.com/tpope/vim-bundler).
 
 Installation
 ------------

doc/rake.txt

@@ -18,7 +18,8 @@ COMMANDS                                        *rake-commands*
 
                                                 *rake-:Rake*
 :Rake [task]            Invoke |:make| followed by |:cwindow| with rake as the
-                        'makeprg'.
+                        'makeprg'.  Uses `bundle exec rake` if bundler.vim is
+                        installed and active for the current project.
 
                                                 *rake-:Rcd*
 :Rcd [directory]        |:cd| relative to the project.

plugin/rake.vim

@@ -273,7 +273,11 @@ function! s:Rake(bang,arg)
   let old_errorformat = &l:errorformat
   call s:push_chdir()
   try
-    let &l:makeprg = 'rake'
+    if exists('b:bundle_root') && b:bundle_root == s:project().path()
+      let &l:makeprg = 'bundle exec rake'
+    else
+      let &l:makeprg = 'rake'
+    endif
     let &l:errorformat = '%D(in\ %f),'
           \.'%\\s%#from\ %f:%l:%m,'
           \.'%\\s%#from\ %f:%l:,'