extensions: Add a tabline formatter for zhihu.nvim (#2742)

autoload/airline/extensions/tabline/zhihu.vim

@@ -0,0 +1,13 @@
+let g:airline#extensions#tabline#formatters#zhihu#formatter = get(g:, 'airline#extensions#tabline#formatters#zhihu#formatter', 'default')
+
+function! airline#extensions#tabline#formatters#zhihu#format(bufnr, buffers)
+  let l:name = bufname(a:bufnr)
+  if match(l:name, 'zhihu://') == -1
+    return airline#extensions#tabline#formatters#{g:airline#extensions#tabline#formatters#zhihu#formatter}#format(a:bufnr, a:buffers)
+  endif
+  let l:prefix = matchstr(fnamemodify(l:name, ':h'), '\d\+')
+  if l:prefix !=# ''
+    let l:prefix .= '/'
+  endif
+  return l:prefix . fnamemodify(l:name, ':t')
+endfunction

doc/airline.txt

@@ -1888,6 +1888,12 @@ zhihu.nvim <https://github.com/pxwg/zhihu.nvim>
 
 * enable/disable zhihu integration >
   let g:airline#extensions#zhihu#enabled = 1
+<  default: 1
+
+* zhihu's tabline formatter >
+  let g:airline#extensions#tabline#formatter = 'zhihu'
+  let g:airline#extensions#tabline#formatters#nerdfont#formatter = 'default'
+<  default: 'default'
 
 
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