feat: allow enabling extensions per buftype

Add a `buftypes` parameter to the extension table; allowing to
filter by current buftype in addition to filetype.

README.md

@@ -887,7 +887,7 @@ You can find a bigger list [here](https://github.com/rockerBOO/awesome-neovim#ta
 ### Extensions
 
 lualine extensions change statusline appearance for a window/buffer with
-specified filetypes.
+specified filetypes or buffertypes.
 
 By default no extensions are loaded to improve performance.
 You can load extensions with:
@@ -927,6 +927,17 @@ local my_extension = { sections = { lualine_a = {'mode'} }, filetypes = {'lua'}
 require('lualine').setup { extensions = { my_extension } }
 ```
 
+To filter by buffer type, for instance, you can apply:
+
+```lua
+local terminal_sec = function() return 'TERMINAL' end
+local my_extension = { sections = { lualine_a = {terminal_sec} }, buftypes = {'terminal'} }
+require('lualine').setup { extensions = { my_extension } }
+```
+
+Note: `filetypes` takes prescedence over `buftypes`. If `filetypes` is present,
+the `buftypes` value is ignored.
+
 ---
 
 ### Refreshing lualine

lua/lualine.lua

@@ -196,14 +196,19 @@ end)
 -- TODO: change this so it uses a hash table instead of iteration over list
 --       to improve redraws. Add buftype / bufname for extensions
 --       or some kind of cond ?
-local function get_extension_sections(current_ft, is_focused, sec_name)
-  for _, extension in ipairs(config.extensions) do
-    if vim.tbl_contains(extension.filetypes, current_ft) then
+local function get_extension_sections(current_bt, current_ft, is_focused, sec_name)
+  local _get_sections = function(extension)
       if is_focused then
         return extension[sec_name]
       else
         return extension['inactive_' .. sec_name] or extension[sec_name]
       end
+  end
+  for _, extension in ipairs(config.extensions) do
+    if extension.filetypes and vim.tbl_contains(extension.filetypes, current_ft) then
+      return _get_sections(extension)
+    elseif extension.buftypes and vim.tbl_contains(extension.buftypes, current_bt) then
+      return _get_sections(extension)
     end
   end
   return nil
@@ -281,6 +286,8 @@ local function status_dispatch(sec_name)
     local current_ft = refresh_real_curwin
         and vim.api.nvim_buf_get_option(vim.api.nvim_win_get_buf(refresh_real_curwin), 'filetype')
       or vim.bo.filetype
+    local current_bt = refresh_real_curwin and vim.api.nvim_buf_get_option(vim.api.nvim_win_get_buf(refresh_real_curwin), 'buftype')
+      or vim.bo.buftype
     local is_focused = focused ~= nil and focused or modules.utils.is_focused()
     if
       vim.tbl_contains(
@@ -291,7 +298,7 @@ local function status_dispatch(sec_name)
       -- disable on specific filetypes
       return nil
     end
-    local extension_sections = get_extension_sections(current_ft, is_focused, sec_name)
+    local extension_sections = get_extension_sections(current_bt, current_ft, is_focused, sec_name)
     if extension_sections ~= nil then
       retval = statusline(extension_sections, is_focused, sec_name == 'winbar')
     else

tests/spec/lualine_spec.lua

@@ -344,6 +344,147 @@ describe('Lualine', function()
     vim.bo.ft = old_ft
   end)
 
+  describe('can filter extensions based on buftype', function ()
+    it('without filetypes filter being present', function()
+      table.insert(config.extensions, {
+        buftypes = { 'acwrite' },
+        sections = {
+          lualine_a = {
+            function()
+              return 'custom_extension_component'
+            end,
+          },
+        },
+      })
+      local old_buftype = vim.bo.buftype
+      -- We cannot set arbitrary values like ft, must be limited to
+      -- neovim known buf types
+      vim.bo.buftype = 'acwrite'
+      require('lualine').setup(config)
+      statusline:expect([===[
+      highlights = {
+          1: lualine_a_normal = { bg = "#a89984", bold = true, fg = "#282828" }
+          2: lualine_transitional_lualine_a_normal_to_lualine_c_normal = { bg = "#3c3836", fg = "#a89984" }
+          3: lualine_c_normal = { bg = "#3c3836", fg = "#a89984" }
+      }
+      |{1: custom_extension_component }
+      {2:}
+      {3:                                                                                           }|
+      ]===])
+      vim.bo.buftype = old_buftype
+    end)
+
+    it('with empty filetypes filter', function()
+      table.insert(config.extensions, {
+        filetypes = {},
+        buftypes = { 'acwrite' },
+        sections = {
+          lualine_a = {
+            function()
+              return 'custom_extension_component'
+            end,
+          },
+        },
+      })
+      local old_buftype = vim.bo.buftype
+      -- We cannot set arbitrary values like ft, must be limited to
+      -- neovim known buf types
+      vim.bo.buftype = 'acwrite'
+      require('lualine').setup(config)
+      statusline:expect([===[
+      highlights = {
+          1: lualine_a_normal = { bg = "#a89984", bold = true, fg = "#282828" }
+          2: lualine_transitional_lualine_a_normal_to_lualine_c_normal = { bg = "#3c3836", fg = "#a89984" }
+          3: lualine_c_normal = { bg = "#3c3836", fg = "#a89984" }
+      }
+      |{1: custom_extension_component }
+      {2:}
+      {3:                                                                                           }|
+      ]===])
+      vim.bo.buftype = old_buftype
+    end)
+
+    it('and does not apply on different type', function()
+      table.insert(config.extensions, {
+        filetypes = {},
+        buftypes = { 'terminal' },
+        sections = {
+          lualine_a = {
+            function()
+              return 'custom_extension_component'
+            end,
+          },
+        },
+      })
+      local old_buftype = vim.bo.buftype
+      -- We cannot set arbitrary values like ft, must be limited to
+      -- neovim known buf types
+      vim.bo.buftype = 'acwrite'
+      require('lualine').setup(config)
+      statusline:expect([===[
+      highlights = {
+          1: lualine_a_normal = { bg = "#a89984", bold = true, fg = "#282828" }
+          2: lualine_transitional_lualine_a_normal_to_lualine_b_normal = { bg = "#504945", fg = "#a89984" }
+          3: lualine_b_normal = { bg = "#504945", fg = "#ebdbb2" }
+          4: lualine_transitional_lualine_b_normal_to_lualine_c_normal = { bg = "#3c3836", fg = "#504945" }
+          5: lualine_c_normal = { bg = "#3c3836", fg = "#a89984" }
+      }
+      |{1: NORMAL }
+      {2:}
+      {3:  master }
+      {4:}
+      {5: [No Name] }
+      {5:                                                                       }
+      {5:  }
+      {4:}
+      {3: Top }
+      {2:}
+      {1:   1:1  }|
+      ]===])
+      vim.bo.buftype = old_buftype
+    end)
+
+    it('and is only checked after filetypes', function()
+      table.insert(config.extensions, {
+        buftypes = { 'quickfix' },
+        sections = {
+          lualine_a = {
+            function()
+              return 'custom_extension_component'
+            end,
+          },
+        },
+      })
+      table.insert(config.extensions, {
+        filetypes = { 'quickfix' },
+        sections = {
+          lualine_a = {
+            function()
+              return 'should_not_be_present'
+            end,
+          },
+        },
+      })
+
+      local old_buftype = vim.bo.buftype
+      -- We cannot set arbitrary values like ft, must be limited to
+      -- neovim known buf types
+      vim.bo.buftype = 'quickfix'
+      require('lualine').setup(config)
+      statusline:expect([===[
+      highlights = {
+          1: lualine_a_normal = { bg = "#a89984", bold = true, fg = "#282828" }
+          2: lualine_transitional_lualine_a_normal_to_lualine_c_normal = { bg = "#3c3836", fg = "#a89984" }
+          3: lualine_c_normal = { bg = "#3c3836", fg = "#a89984" }
+      }
+      |{1: custom_extension_component }
+      {2:}
+      {3:                                                                                           }|
+      ]===])
+      vim.bo.buftype = old_buftype
+    end)
+  end)
+
   -- TODO: figure put why some of the tablines tests fail in CI
   describe('tabline', function()
     local tab_conf = vim.deepcopy(config)