From aea541a1e8ce91416cfdf2eb6f52a536d968ef5d Mon Sep 17 00:00:00 2001
From: Daniel Hahler <git@thequod.de>
Date: Mon, 3 Feb 2014 21:12:58 +0100
Subject: [PATCH 1/3] Prefer remapping of `<Plug>` over `<CR>`

`<CR>` might be mapped to `<CR><Plug>Foo` and must then not get
remapped with `<script>`.
---
 plugin/endwise.vim | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/plugin/endwise.vim b/plugin/endwise.vim
index 0dc5a43..2f30f20 100644
--- a/plugin/endwise.vim
+++ b/plugin/endwise.vim
@@ -63,12 +63,12 @@ endif
 if !exists('g:endwise_no_mappings')
   if maparg('<CR>','i') =~# '<C-R>=.*crend(.)<CR>\|<\%(Plug\|SNR\|SID\)>.*End'
     " Already mapped
-  elseif maparg('<CR>','i') =~ '<CR>'
-    exe "imap <script> <C-X><CR> ".maparg('<CR>','i')."<SID>AlwaysEnd"
-    exe "imap <script> <CR>      ".maparg('<CR>','i')."<SID>DiscretionaryEnd"
   elseif maparg('<CR>','i') =~ '<Plug>\w\+CR'
     exe "imap <C-X><CR> ".maparg('<CR>', 'i')."<Plug>AlwaysEnd"
     exe "imap <CR> ".maparg('<CR>', 'i')."<Plug>DiscretionaryEnd"
+  elseif maparg('<CR>','i') =~ '<CR>'
+    exe "imap <script> <C-X><CR> ".maparg('<CR>','i')."<SID>AlwaysEnd"
+    exe "imap <script> <CR>      ".maparg('<CR>','i')."<SID>DiscretionaryEnd"
   else
     imap <C-X><CR> <CR><Plug>AlwaysEnd
     imap <CR>      <CR><Plug>DiscretionaryEnd

From 13650891d9667eeb9bd3f2ad83e0e4a8de7877dd Mon Sep 17 00:00:00 2001
From: Daniel Hahler <git@thequod.de>
Date: Mon, 3 Feb 2014 21:21:05 +0100
Subject: [PATCH 2/3] Only call `maparg` once

---
 plugin/endwise.vim | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/plugin/endwise.vim b/plugin/endwise.vim
index 2f30f20..ccc801d 100644
--- a/plugin/endwise.vim
+++ b/plugin/endwise.vim
@@ -61,14 +61,15 @@ if maparg("<Plug>DiscretionaryEnd") == ""
 endif
 
 if !exists('g:endwise_no_mappings')
-  if maparg('<CR>','i') =~# '<C-R>=.*crend(.)<CR>\|<\%(Plug\|SNR\|SID\)>.*End'
+  let maparg = maparg('<CR>', 'i')
+  if maparg =~# '<C-R>=.*crend(.)<CR>\|<\%(Plug\|SNR\|SID\)>.*End'
     " Already mapped
-  elseif maparg('<CR>','i') =~ '<Plug>\w\+CR'
-    exe "imap <C-X><CR> ".maparg('<CR>', 'i')."<Plug>AlwaysEnd"
-    exe "imap <CR> ".maparg('<CR>', 'i')."<Plug>DiscretionaryEnd"
-  elseif maparg('<CR>','i') =~ '<CR>'
-    exe "imap <script> <C-X><CR> ".maparg('<CR>','i')."<SID>AlwaysEnd"
-    exe "imap <script> <CR>      ".maparg('<CR>','i')."<SID>DiscretionaryEnd"
+  elseif maparg =~ '<Plug>\w\+CR'
+    exe "imap <C-X><CR> ".maparg."<Plug>AlwaysEnd"
+    exe "imap <CR>      ".maparg."<Plug>DiscretionaryEnd"
+  elseif maparg =~ '<CR>'
+    exe "imap <script> <C-X><CR> ".maparg."<SID>AlwaysEnd"
+    exe "imap <script> <CR>      ".maparg."<SID>DiscretionaryEnd"
   else
     imap <C-X><CR> <CR><Plug>AlwaysEnd
     imap <CR>      <CR><Plug>DiscretionaryEnd

From bc755623e64aea418c9f644ca73eba02ee93d878 Mon Sep 17 00:00:00 2001
From: Daniel Hahler <git@thequod.de>
Date: Mon, 3 Feb 2014 21:34:27 +0100
Subject: [PATCH 3/3] Use `<unique>` maps, catch already-exists error and
 provide help

Instead of silently overwriting any (not previously handled) existing
mappings, use `<unique>` inside a `try` block and provide help to fix
it.
---
 plugin/endwise.vim | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

diff --git a/plugin/endwise.vim b/plugin/endwise.vim
index ccc801d..20b42c9 100644
--- a/plugin/endwise.vim
+++ b/plugin/endwise.vim
@@ -71,8 +71,21 @@ if !exists('g:endwise_no_mappings')
     exe "imap <script> <C-X><CR> ".maparg."<SID>AlwaysEnd"
     exe "imap <script> <CR>      ".maparg."<SID>DiscretionaryEnd"
   else
-    imap <C-X><CR> <CR><Plug>AlwaysEnd
-    imap <CR>      <CR><Plug>DiscretionaryEnd
+    " Use <unique> to get a warning, if user maps would get overwritten,
+    " then catch the error and provide help to fix it.
+    for m in [
+          \ 'imap <unique> <C-X><CR> <CR><Plug>AlwaysEnd',
+          \ 'imap <unique> <CR>      <CR><Plug>DiscretionaryEnd']
+      try
+        exec m
+      catch /^Vim\%((\a\+)\)\=:E227/  " E227: mapping already exists for ^X^M
+        let exception_msg = substitute(v:exception, '^\S\+: ', '', '')
+        echohl WarningMsg
+        echom 'endwise: not overwriting existing map ('.exception_msg.').'
+              \ 'Set g:endwise_no_mappings=1 to skip setup of mappings.'
+        echohl None
+      endtry
+    endfor
   endif
 endif