feat: use a new diagnostic module for nvim 0.6

- Close #6 Thanks to @alexlafroscia for the initial work

autoload/lightline/lsp.vim

@@ -12,42 +12,42 @@ function! lightline#lsp#hints() abort
   if !lightline#lsp#linted()
     return ''
   endif
-  let l:counts = luaeval('vim.lsp.diagnostic.get_count('.bufnr().', [[Hint]])')
+  let l:counts = luaeval("require('lightline-lsp')._get_diagnostic_count('hint')")
   return l:counts == 0 ? '' : printf(s:indicator_hints . '%d', counts)
 endfunction
 
 function! lightline#lsp#infos() abort
   if !lightline#lsp#linted()
     return ''
   endif
-  let l:counts = luaeval('vim.lsp.diagnostic.get_count('.bufnr().', [[Information]])')
+  let l:counts = luaeval("require('lightline-lsp')._get_diagnostic_count('info')")
   return l:counts == 0 ? '' : printf(s:indicator_infos . '%d', counts)
 endfunction
 
 function! lightline#lsp#warnings() abort
   if !lightline#lsp#linted()
     return ''
   endif
-  let l:counts = luaeval('vim.lsp.diagnostic.get_count('.bufnr().', [[Warning]])')
+  let l:counts = luaeval("require('lightline-lsp')._get_diagnostic_count('warn')")
   return l:counts == 0 ? '' : printf(s:indicator_warnings . '%d', counts)
 endfunction
 
 function! lightline#lsp#errors() abort
   if !lightline#lsp#linted()
     return ''
   endif
-  let l:counts = luaeval('vim.lsp.diagnostic.get_count('.bufnr().', [[Error]])')
+  let l:counts = luaeval("require('lightline-lsp')._get_diagnostic_count('error')")
   return l:counts == 0 ? '' : printf(s:indicator_errors . '%d', counts)
 endfunction
 
 function! lightline#lsp#ok() abort
   if !lightline#lsp#linted()
     return ''
   endif
-  let l:hint_counts = luaeval('vim.lsp.diagnostic.get_count('.bufnr().', [[Hint]])')
-  let l:info_counts = luaeval('vim.lsp.diagnostic.get_count('.bufnr().', [[Information]])')
-  let l:warn_counts = luaeval('vim.lsp.diagnostic.get_count('.bufnr().', [[Warning]])')
-  let l:error_counts = luaeval('vim.lsp.diagnostic.get_count('.bufnr().', [[Error]])')
+  let l:hint_counts = luaeval("require('lightline-lsp')._get_diagnostic_count('hint')")
+  let l:info_counts = luaeval("require('lightline-lsp')._get_diagnostic_count('info')")
+  let l:warn_counts = luaeval("require('lightline-lsp')._get_diagnostic_count('warn')")
+  let l:error_counts = luaeval("require('lightline-lsp')._get_diagnostic_count('error')")
   let l:counts = l:hint_counts+l:info_counts+l:warn_counts+l:error_counts
   return l:counts == 0 ? s:indicator_ok : ''
 endfunction

lua/lightline-lsp.lua

@@ -0,0 +1,49 @@
+local M = {}
+
+local function is_lsp_attached()
+  return next(vim.lsp.buf_get_clients(0))
+end
+
+local function get_count(buffer_number, diagnostic_type)
+  if vim.diagnostic == nil then
+    -- starting nvim-0.5
+    local severity = ({
+      hint = 'Hint',
+      info = 'Information',
+      warn = 'Warn',
+      error = 'Error'
+    })[diagnostic_type]
+
+    return vim.lsp.diagnostic.get_count(buffer_number, severity)
+  else
+    -- starting nvim-0.6
+    local severity = ({
+      hint = vim.diagnostic.severity.HINT,
+      info = vim.diagnostic.severity.INFO,
+      warn = vim.diagnostic.severity.WARN,
+      error = vim.diagnostic.severity.ERROR
+    })[diagnostic_type]
+
+    return vim.tbl_count(vim.diagnostic.get(
+      buffer_number,
+      {
+        severity = severity
+      }
+    ))
+  end
+end
+
+M._get_diagnostic_count = function (diagnostic_type)
+  if not is_lsp_attached() then
+    return 0
+  end
+
+  local active_clients = vim.lsp.get_active_clients()
+  if vim.tbl_isempty(active_clients) then
+    return 0
+  end
+
+  return get_count(vim.api.nvim_get_current_buf(), diagnostic_type)
+end
+
+return M