From 7300acc032403be81a9297f2cf6317260730e655 Mon Sep 17 00:00:00 2001
From: Tim Brooks <brooks@cern.ch>
Date: Wed, 28 Jan 2015 19:15:53 +0000
Subject: [PATCH] Use maparg to check for previous mappings

As per issue #12, fail to map using map-<unique> and emit a message
directing users to #18
---
 autoload/yankstack.vim | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/autoload/yankstack.vim b/autoload/yankstack.vim
index 8feb49e..2e36fc8 100644
--- a/autoload/yankstack.vim
+++ b/autoload/yankstack.vim
@@ -161,8 +161,12 @@ function! yankstack#setup()
   let word_characters = split("qwertyuiopasdfghjklzxcvbnm1234567890_", '\zs')
 
   for key in g:yankstack_yank_keys
-    exec 'nnoremap <silent> <expr>'  key '<SID>yank_with_key("' . key . '")'
-    exec 'xnoremap <silent> <expr>'  key '<SID>yank_with_key("' . key . '")'
+    if maparg(key, "x") != ""
+        echom "The key " . key . " is already mapped as " . maparg(key, "x")
+        echom "See https://github.com/maxbrunsfeld/vim-yankstack/issues/18 for details"
+    endif
+    exec 'nnoremap <unique> <expr>'  key '<SID>yank_with_key("' . key . '")'
+    exec 'xnoremap <unique> <expr>'  key '<SID>yank_with_key("' . key . '")'
   endfor
 
   for key in paste_keys