Include Scala ctags definition for Tagbar

Uses Tagbar’s “deffile” support to make the sidebar work out of the box
if the user has Tagbar installed, no ~/.ctags modification needed.

ctags/scala.ctags

@@ -0,0 +1,13 @@
+--langdef=scala
+--langmap=scala:.scala
+
+--regex-scala=/^[ \t ]*((abstract|final|sealed|implicit|lazy)[ \t ]*)*(private[^ ]*|protected)?[ \t ]*class[ \t ]+([a-zA-Z0-9_]+)/\4/c,classes/
+--regex-scala=/^[ \t ]*((abstract|final|sealed|implicit|lazy)[ \t ]*)*(private[^ ]*|protected)?[ \t ]*object[ \t ]+([a-zA-Z0-9_]+)/\4/c,objects/
+--regex-scala=/^[ \t ]*((abstract|final|sealed|implicit|lazy)[ \t ]*)*(private[^ ]*|protected)?[ \t ]*((abstract|final|sealed|implicit|lazy)[ \t ]*)*case class[ \t ]+([a-zA-Z0-9_]+)/\6/c,case classes/
+--regex-scala=/^[ \t ]*((abstract|final|sealed|implicit|lazy)[ \t ]*)*(private[^ ]*|protected)?[ \t ]*case object[ \t ]+([a-zA-Z0-9_]+)/\4/c,case objects/
+--regex-scala=/^[ \t ]*((abstract|final|sealed|implicit|lazy)[ \t ]*)*(private[^ ]*|protected)?[ \t ]*trait[ \t ]+([a-zA-Z0-9_]+)/\4/t,traits/
+--regex-scala=/^[ \t ]*type[ \t ]+([a-zA-Z0-9_]+)/\1/T,types/
+--regex-scala=/^[ \t ]*((abstract|final|sealed|implicit|lazy|private[^ ]*(\[[a-z]*\])*|protected)[ \t ]*)*def[ \t ]+([a-zA-Z0-9_]+)/\4/m,methods/
+--regex-scala=/^[ \t ]*((abstract|final|sealed|implicit|lazy|private[^ ]*|protected)[ \t ]*)*val[ \t ]+([a-zA-Z0-9_]+)/\3/l,constants/
+--regex-scala=/^[ \t ]*((abstract|final|sealed|implicit|lazy|private[^ ]*|protected)[ \t ]*)*var[ \t ]+([a-zA-Z0-9_]+)/\3/l,variables/
+--regex-scala=/^[ \t ]*package[ \t ]+([a-zA-Z0-9_.]+)/\1/p,packages/

doc/scala.txt

@@ -6,8 +6,40 @@ This plugin is only available if 'compatible' is not set.
 ==============================================================================
 INTRODUCTION                                    *scala*
 
-Syntax highlighting and helper functions for the scala language.
+Syntax highlighting and helper functions for the scala language. Extras
+include:
 
+  - Sorting of import statements, configurable to your conventions.
+  - Tagbar support to navigate definitions within a file in the plugin's
+    sidebar window.
+  - ...and probably more that we've forgotten to update in this doc.
+
+==============================================================================
+OPTIONS                                         *scala-options*
+
+Use these options to control behavior of the plugin. Default values are
+indicated in the examples.
+
+                                           *'g:scala_use_builtin_tagbar_defs'*
+If you are using the Tagbar Vim plugin, vim-scala includes a Tagbar type
+definition and ctags definition for Scala, so you can use Tagbar immediately.
+If you have your own ctags definition in `~/.ctags` and prefer to use it, set
+this option to 0 (we would appreciate contributions if you've improved the
+ctags definition!).
+
+Note that Tagbar's ctags definition for Scala is not used to generate a
+|tags| file that Vim can use to navigate to definitions in other files, only
+for the plugin sidebar. Feel free to copy `vim-scala/ctags/scala.ctags` into
+your own `~/.ctags` if you wish to generate |tags| files.
+>
+    let g:scala_use_builtin_tagbar_defs = 1
+<
+                                           *'g:scala_use_default_keymappings'*
+Set this option to disable definition of all mappings provided by vim-scala.
+See |scala-mappings|.
+>
+    let g:scala_use_default_keymappings = 1
+<
 ==============================================================================
 COMMANDS                                        *scala-commands*
 

ftplugin/scala.vim

@@ -142,43 +142,6 @@ if globpath(&rtp, 'plugin/fuf.vim') != ''
     endif
 endif
 
-
-"
-" TagBar
-"
-let g:tagbar_type_scala = {
-    \ 'ctagstype' : 'scala',
-    \ 'kinds'     : [
-      \ 'p:packages:1',
-      \ 'V:values',
-      \ 'v:variables',
-      \ 'T:types',
-      \ 't:traits',
-      \ 'o:objects',
-      \ 'a:aclasses',
-      \ 'c:classes',
-      \ 'r:cclasses',
-      \ 'm:methods'
-    \ ],
-    \ 'sro'        : '.',
-    \ 'kind2scope' : {
-        \ 'T' : 'type',
-        \ 't' : 'trait',
-        \ 'o' : 'object',
-        \ 'a' : 'abstract class',
-        \ 'c' : 'class',
-        \ 'r' : 'case class'
-    \ },
-    \ 'scope2kind' : {
-      \ 'type' : 'T',
-      \ 'trait' : 't',
-      \ 'object' : 'o',
-      \ 'abstract class' : 'a',
-      \ 'class' : 'c',
-      \ 'case class' : 'r'
-    \ }
-\ }
-
 function! s:CreateOrExpression(keywords)
   return '('.join(a:keywords, '|').')'
 endfunction

ftplugin/scala/tagbar.vim

@@ -0,0 +1,49 @@
+"
+" Support for Tagbar -- https://github.com/majutsushi/tagbar
+"
+" Hat tip to Leonard Ehrenfried for the built-in ctags deffile:
+"    https://leonard.io/blog/2013/04/editing-scala-with-vim/
+"
+if !executable('ctags')
+  finish
+elseif !exists(':Tagbar')
+  finish
+endif
+
+let g:tagbar_type_scala = {
+    \ 'ctagstype' : 'scala',
+    \ 'kinds'     : [
+      \ 'p:packages:1',
+      \ 'V:values',
+      \ 'v:variables',
+      \ 'T:types',
+      \ 't:traits',
+      \ 'o:objects',
+      \ 'a:aclasses',
+      \ 'c:classes',
+      \ 'r:cclasses',
+      \ 'm:methods'
+    \ ],
+    \ 'sro'        : '.',
+    \ 'kind2scope' : {
+        \ 'T' : 'type',
+        \ 't' : 'trait',
+        \ 'o' : 'object',
+        \ 'a' : 'abstract class',
+        \ 'c' : 'class',
+        \ 'r' : 'case class'
+    \ },
+    \ 'scope2kind' : {
+      \ 'type' : 'T',
+      \ 'trait' : 't',
+      \ 'object' : 'o',
+      \ 'abstract class' : 'a',
+      \ 'class' : 'c',
+      \ 'case class' : 'r'
+    \ }
+\ }
+
+" In case you've updated/customized your ~/.ctags and prefer to use it.
+if get(g:, 'scala_use_builtin_tagbar_defs', 1)
+  let g:tagbar_type_scala.deffile = expand('<sfile>:p:h:h:h') . '/ctags/scala.ctags'
+endif