Refactor NavigateUp/Down to use standard locations

The NavigatUp/NavigateDown functions have, until now, had their own
navigation implementation: setting a mark, changing the cursor position.

However, as we have standard functions for handling locations, it makes
sense to use them, especially with the new optional user callback, as this
makes the callback usage more predictable. The callback will now be
passed a "location" object (which looks like a quickfix item) with the
same structure as the locations returned to GotoDefinition callbacks and
FindUsages callbacks etc.

Author: nickspoons

autoload/OmniSharp/actions/navigate.vim

@@ -1,39 +1,34 @@
 let s:save_cpo = &cpoptions
 set cpoptions&vim
 
+" Navigate to the next member definition in the class.
+" Optional arguments:
+" Callback: When a callback is passed in, it is called after the response is
+"           returned with the member location. No navigation is performed when a
+"           callback is passed in.
 function! OmniSharp#actions#navigate#Down(...) abort
-  if a:0 > 0
-    let Callback = a:1
-    call s:Navigate(1, Callback)
-  else
-    call s:Navigate(1)
-  endif
+  call s:Navigate(1, a:0 ? a:1 : function('OmniSharp#locations#Navigate'))
 endfunction
 
+" See OmniSharp#actions#navigate#Down
 function! OmniSharp#actions#navigate#Up(...) abort
-  if a:0 > 0
-    let Callback = a:1
-    call s:Navigate(0, Callback)
-  else
-    call s:Navigate(0)
-  endif
+  call s:Navigate(0, a:0 ? a:1 : function('OmniSharp#locations#Navigate'))
 endfunction
 
-function! s:Navigate(down, ...) abort
+function! s:Navigate(down, Callback) abort
   if g:OmniSharp_server_stdio
-    let Callback = a:0 ? a:1 : function('s:NavigateRH')
-    let opts = { 'ResponseHandler': Callback }
+    let RH = function('s:StdioNavigateRH', [a:Callback])
+    let opts = { 'ResponseHandler': RH }
     call OmniSharp#stdio#Request(a:down ? '/navigatedown' : '/navigateup', opts)
   else
     call OmniSharp#py#Eval(a:down ? 'navigateDown()' : 'navigateUp()')
     call OmniSharp#py#CheckForError()
   endif
 endfunction
 
-function! s:NavigateRH(response) abort
+function! s:StdioNavigateRH(Callback, response) abort
   if !a:response.Success | return | endif
-  normal! m'
-  call cursor(a:response.Body.Line, a:response.Body.Column)
+  call a:Callback(OmniSharp#locations#Parse([a:response.Body])[0])
 endfunction
 
 let &cpoptions = s:save_cpo