Multiple mappings possible for selection cycling

This change also makes the arrow keys behave like Tab and Shift-Tab.

Fixes issue #83.

README.md

@@ -526,28 +526,31 @@ Default: `30`
 
     let g:ycm_max_diagnostics_to_display = 30
 
-### The `g:ycm_key_select_completion` option
+### The `g:ycm_key_list_select_completion` option
 
-This option controls the key mapping used to select the first completion string.
+This option controls the key mappings used to select the first completion
-Invoking it repeatedly cycles forward through the completion list.
+string.  Invoking any of them repeatedly cycles forward through the completion
+list.
 
-Default: `<TAB>`
+Some users like adding `<Enter>` to this list.
 
-    let g:ycm_key_select_completion = '<TAB>'
+Default: `['<TAB>', '<Down>']`
 
-### The `g:ycm_key_previous_completion` option
+    let g:ycm_key_list_select_completion = ['<TAB>', '<Down>']
 
-This option controls the key mapping used to select the previous completion
+### The `g:ycm_key_list_previous_completion` option
-string. Invoking it repeatedly cycles backwards through the completion list.
 
-Note that the default of `<S-TAB>` means Shift-TAB. Also note that the default
+This option controls the key mappings used to select the previous completion
-mapping will probably only work in GUI Vim (Gvim or MacVim) and not in plain
+string. Invoking any of them repeatedly cycles backwards through the completion
-console Vim because the terminal usually does not forward modifier key
+list.
-combinations to Vim.
 
-Default: `<S-TAB>`
+Note that one of the defaults is `<S-TAB>` which means Shift-TAB. That mapping
+will probably only work in GUI Vim (Gvim or MacVim) and not in plain console Vim
+because the terminal usually does not forward modifier key combinations to Vim.
 
-    let g:ycm_key_previous_completion = '<S-TAB>'
+Default: `['<S-TAB>', '<Up>']`
+
+    let g:ycm_key_previous_completion = ['<S-TAB>', '<Up>']
 
 ### The `g:ycm_key_invoke_completion` option
 

autoload/youcompleteme.vim

@@ -53,38 +53,13 @@ function! youcompleteme#Enable()
   augroup END
 
   call s:SetUpCompleteopt()
+  call s:SetUpKeyMappings()
+  call s:ForceSyntasticCFamilyChecker()
 
   if g:ycm_allow_changing_updatetime
     set ut=2000
   endif
 
-  " Needed so that YCM is used as the syntastic checker
-  let g:syntastic_cpp_checkers = ['ycm']
-  let g:syntastic_c_checkers = ['ycm']
-  let g:syntastic_objc_checkers = ['ycm']
-  let g:syntastic_objcpp_checkers = ['ycm']
-
-  " With this command, when the completion window is visible, the tab key
-  " (default) will select the next candidate in the window. In vim, this also
-  " changes the typed-in text to that of the candidate completion.
-  exe 'inoremap <expr>' . g:ycm_key_select_completion .
-        \ ' pumvisible() ? "\<C-n>" : "\' . g:ycm_key_select_completion .'"'
-
-  " This selects the previous candidate for shift-tab (default)
-  exe 'inoremap <expr>' . g:ycm_key_previous_completion .
-        \ ' pumvisible() ? "\<C-p>" : "\' . g:ycm_key_previous_completion .'"'
-
-  if strlen(g:ycm_key_invoke_completion)
-    " <c-x><c-o> trigger omni completion, <c-p> deselects the first completion
-    " candidate that vim selects by default
-    exe 'inoremap <unique> ' . g:ycm_key_invoke_completion . ' <C-X><C-O><C-P>'
-  endif
-
-  if strlen(g:ycm_key_detailed_diagnostics)
-    exe 'nnoremap <unique> ' . g:ycm_key_detailed_diagnostics .
-          \ ' :YcmShowDetailedDiagnostic<cr>'
-  endif
-
   py import sys
   py import vim
   exe 'python sys.path.insert( 0, "' . s:script_folder_path . '/../python" )'
@@ -98,6 +73,60 @@ function! youcompleteme#Enable()
 endfunction
 
 
+function! s:SetUpKeyMappings()
+  " The g:ycm_key_select_completion and g:ycm_key_previous_completion used to
+  " exist and are now here purely for the sake of backwards compatibility; we
+  " don't want to break users if we can avoid it.
+
+  if exists('g:ycm_key_select_completion') &&
+        \ index(g:ycm_key_list_select_completion,
+        \       g:ycm_key_select_completion) == -1
+    call add(g:ycm_key_list_select_completion, g:ycm_key_select_completion)
+  endif
+
+  if exists('g:ycm_key_previous_completion') &&
+        \ index(g:ycm_key_list_previous_completion,
+        \       g:ycm_key_previous_completion) == -1
+    call add(g:ycm_key_list_previous_completion, g:ycm_key_previous_completion)
+  endif
+
+  for key in g:ycm_key_list_select_completion
+    " With this command, when the completion window is visible, the tab key
+    " (default) will select the next candidate in the window. In vim, this also
+    " changes the typed-in text to that of the candidate completion.
+    exe 'inoremap <expr>' . key .
+          \ ' pumvisible() ? "\<C-n>" : "\' . key .'"'
+  endfor
+
+
+  for key in g:ycm_key_list_previous_completion
+    " This selects the previous candidate for shift-tab (default)
+    exe 'inoremap <expr>' . key .
+          \ ' pumvisible() ? "\<C-p>" : "\' . key .'"'
+  endfor
+
+  if strlen(g:ycm_key_invoke_completion)
+    " <c-x><c-o> trigger omni completion, <c-p> deselects the first completion
+    " candidate that vim selects by default
+    exe 'inoremap <unique> ' . g:ycm_key_invoke_completion . ' <C-X><C-O><C-P>'
+  endif
+
+  if strlen(g:ycm_key_detailed_diagnostics)
+    exe 'nnoremap <unique> ' . g:ycm_key_detailed_diagnostics .
+          \ ' :YcmShowDetailedDiagnostic<cr>'
+  endif
+endfunction
+
+
+function! s:ForceSyntasticCFamilyChecker()
+  " Needed so that YCM is used as the syntastic checker
+  let g:syntastic_cpp_checkers = ['ycm']
+  let g:syntastic_c_checkers = ['ycm']
+  let g:syntastic_objc_checkers = ['ycm']
+  let g:syntastic_objcpp_checkers = ['ycm']
+endfunction
+
+
 function! s:AllowedToCompleteInCurrentFile()
   " If the user set the current filetype as a filetype that YCM should ignore,
   " then we don't do anything

plugin/youcompleteme.vim

@@ -80,11 +80,11 @@ let g:ycm_autoclose_preview_window_after_completion =
 let g:ycm_max_diagnostics_to_display =
       \ get( g:, 'ycm_max_diagnostics_to_display', 30 )
 
-let g:ycm_key_select_completion =
+let g:ycm_key_list_select_completion =
-      \ get( g:, 'ycm_key_select_completion', '<TAB>' )
+      \ get( g:, 'ycm_key_list_select_completion', ['<TAB>', '<Down>'] )
 
-let g:ycm_key_previous_completion =
+let g:ycm_key_list_previous_completion =
-      \ get( g:, 'ycm_key_previous_completion', '<S-TAB>' )
+      \ get( g:, 'ycm_key_list_previous_completion', ['<S-TAB>', '<Up>'] )
 
 let g:ycm_key_invoke_completion =
       \ get( g:, 'ycm_key_invoke_completion', '<C-Space>' )