Add tag datatype (#698)

Closes #680

Add `g:tagbar_show_data_type` field to show the tag datatype next to the tag in the tagbar window
This uses the `--fields=t` field to get the datatype from ctags. If not found, then it will attempt to derive the datatype by extracting all the output from the `pattern` preceeding the tag name.

More testing is needed on other languages. So far this has been stable with C / C++ files parsing the datatype from ctags output. It has also been tested with Java files for the inferred datatype by parsing the pattern line and pulling out everything prior to the tag.

autoload/tagbar.vim

@@ -1342,7 +1342,7 @@ function! s:ExecuteCtagsOnFile(fname, realfname, typeinfo) abort
                           \ '-',
                           \ '--format=2',
                           \ '--excmd=pattern',
-                          \ '--fields=nksSaf',
+                          \ '--fields=nksSaft',
                           \ '--sort=no',
                           \ '--append=no'
                           \ ]
@@ -1541,6 +1541,17 @@ function! s:ProcessTag(name, filename, pattern, fields, is_split, typeinfo, file
 
     let a:fileinfo.fline[taginfo.fields.line] = taginfo
 
+    if has_key(taginfo.fields, 'typeref')
+        let typeref = taginfo.fields.typeref
+        let delimit = stridx(typeref, ':')
+        let key = strpart(typeref, 0, delimit)
+        if key ==# 'typename'
+            let taginfo.data_type = substitute(strpart(typeref, delimit + 1), '\t', '', 'g')
+        else
+            let taginfo.data_type = key
+        endif
+    endif
+
     " If this filetype doesn't have any scope information then we can stop
     " here after adding the tag to the list
     if !has_key(a:typeinfo, 'scope2kind')

autoload/tagbar/prototypes/basetag.vim

@@ -15,6 +15,7 @@ function! tagbar#prototypes#basetag#new(name) abort
     let newobj.fields.line   = 0
     let newobj.fields.column = 0
     let newobj.prototype     = ''
+    let newobj.data_type     = ''
     let newobj.path          = ''
     let newobj.fullpath      = a:name
     let newobj.depth         = 0
@@ -30,6 +31,7 @@ function! tagbar#prototypes#basetag#new(name) abort
     let newobj.isSplitTag = function(s:add_snr('s:isSplitTag'))
     let newobj.isKindheader = function(s:add_snr('s:isKindheader'))
     let newobj.getPrototype = function(s:add_snr('s:getPrototype'))
+    let newobj.getDataType = function(s:add_snr('s:getDataType'))
     let newobj._getPrefix = function(s:add_snr('s:_getPrefix'))
     let newobj.initFoldState = function(s:add_snr('s:initFoldState'))
     let newobj.getClosedParentTline = function(s:add_snr('s:getClosedParentTline'))
@@ -72,6 +74,11 @@ function! s:getPrototype(short) abort dict
     return self.prototype
 endfunction
 
+" s:getDataType() {{{1
+function! s:getDataType() abort dict
+    return self.data_type
+endfunction
+
 " s:_getPrefix() {{{1
 function! s:_getPrefix() abort dict
     let fileinfo = self.fileinfo

autoload/tagbar/prototypes/normaltag.vim

@@ -14,6 +14,7 @@ function! tagbar#prototypes#normaltag#new(name) abort
     let newobj.strfmt = function(s:add_snr('s:strfmt'))
     let newobj.str = function(s:add_snr('s:str'))
     let newobj.getPrototype = function(s:add_snr('s:getPrototype'))
+    let newobj.getDataType = function(s:add_snr('s:getDataType'))
 
     return newobj
 endfunction
@@ -32,10 +33,16 @@ function! s:strfmt() abort dict
         let suffix .= ' : ' . self.fields.type
     elseif has_key(get(typeinfo, 'kind2scope', {}), self.fields.kind)
         let scope = s:maybe_map_scope(typeinfo.kind2scope[self.fields.kind])
-        let suffix .= ' : ' . scope
+        if !g:tagbar_show_data_type
+            let suffix .= ' : ' . scope
+        endif
     endif
     let prefix = self._getPrefix()
 
+    if g:tagbar_show_data_type && self.getDataType() !=# ''
+        let suffix .= ' : ' . self.getDataType()
+    endif
+
     if g:tagbar_show_tag_linenumbers == 1
         let suffix .= ' [' . self.fields.line . ']'
     elseif g:tagbar_show_tag_linenumbers == 2
@@ -78,6 +85,8 @@ function! s:getPrototype(short) abort dict
         endif
 
         let line = getbufline(bufnr, self.fields.line)[0]
+        " If prototype includes declaration, remove the '=' and anything after
+        let line = substitute(line, '\s*=.*', '', '')
         let list = split(line, '\zs')
 
         let start = index(list, '(')
@@ -124,6 +133,39 @@ function! s:getPrototype(short) abort dict
     return prototype
 endfunction
 
+" s:getDataType() {{{1
+function! s:getDataType() abort dict
+    if self.data_type !=# ''
+        let data_type = self.data_type
+    else
+        " This is a fallthrough attempt to derive the data_type from the line
+        " in the event ctags doesn't return the typeref field
+        let bufnr = self.fileinfo.bufnr
+
+        if self.fields.line == 0 || !bufloaded(bufnr)
+            " No linenumber available or buffer not loaded (probably due to
+            " 'nohidden'), try the pattern instead
+            return substitute(self.pattern, '^\\M\\^\\C\s*\(.*\)\\$$', '\1', '')
+        endif
+
+        let line = getbufline(bufnr, self.fields.line)[0]
+        let data_type = substitute(line, '\s*' . self.name . '.*', '', '')
+
+        " Strip off the path if we have one along with any spaces prior to the
+        " path
+        if self.path !=# ''
+            let data_type = substitute(data_type, '\s*' . self.path . self.typeinfo.sro, '', '')
+        endif
+
+        " Strip off leading spaces
+        let data_type = substitute(data_type, '^\s\+', '', '')
+
+        let self.data_type = data_type
+    endif
+
+    return data_type
+endfunction
+
 " s:add_snr() {{{1
 function! s:add_snr(funcname) abort
     if !exists('s:snr')

doc/tagbar.txt

@@ -671,7 +671,17 @@ Example:
 >
         let g:tagbar_show_balloon = 0
 <
+                                                    *g:tagbar_show_data_type*
+g:tagbar_show_data_type~
+Default: 0
 
+When set to non-zero, the tag data-type will be displayed to the right of the
+tag in the tagbar window.
+
+Example:
+>
+        let g:tagbar_show_data_type = 1
+<
                                                     *g:tagbar_show_visibility*
 g:tagbar_show_visibility~
 Default: 1

plugin/tagbar.vim

@@ -104,6 +104,7 @@ function! s:setup_options() abort
         \ ['scopestrs', {}],
         \ ['scrolloff', 0],
         \ ['show_balloon', 1],
+        \ ['show_data_type', 0],
         \ ['show_visibility', 1],
         \ ['show_linenumbers', 0],
         \ ['show_tag_count', 0],