feat: add option to invert component icon alignment (#666)

* feat: add option to invert component icon alignment

Invert component status icon if variable is set `icon_right = true`.

* refactor: use string for icon alignment

Change conditional variable for icon left/right alignment from Boolean
to `icon_alignment = 'right'`.

* refactor: check icon table for alignment variable

Determine component status output from icon_alignment variable.
Provides alignment variables for generic component and filetype
devicons.

`component = { 'name', icon = {'*', align = 'right'} }`
`component = { 'filetype', icon_alignment = 'right' }`

* style: restore previous formatting on line 79

* refactor: set `self.option.icon` as table

* fix: forgot non-color icon alignment

* fix: remove redundant variable assignment

* docs: add README examples for icon alignment

Include configuration examples for icon alignment to README file.

* test: add test for filetype components icon align

Ensure testability for filetype icons being aligned to right side.

README.md

@@ -362,6 +362,9 @@ sections = {
       -- As table it must contain the icon as first entry and can use
       -- color option to custom color the icon. Example:
       -- {'branch', icon = ''} / {'branch', icon = {'', color={fg='green'}}}
+
+      -- icon position can also be set to the right side from table. Example:
+      -- {'branch', icon = {'', align='right', color={fg='green'}}}
       icon = nil,
 
       separator = nil,      -- Determines what separator to use for the component.
@@ -568,7 +571,10 @@ sections = {
     {
       'filetype',
       colored = true,   -- Displays filetype icon in color if set to true
-      icon_only = false -- Display only an icon for filetype
+      icon_only = false, -- Display only an icon for filetype
+      icon = { align = 'right' }, -- Display filetype icon on the right hand side
+      -- icon =    {'X', align='right'}
+      -- Icon string ^ in table is ignored in filetype component
     }
   }
 }

lua/lualine/component.lua

@@ -108,14 +108,22 @@ function M:apply_highlights(default_highlight)
   end
 end
 
----apply icon in front of component (prepemds component with icon)
+---apply icon to component (appends/prepemds component with icon)
 function M:apply_icon()
   local icon = self.options.icon
   if self.options.icons_enabled and icon then
     if type(icon) == 'table' then
       icon = icon[1]
     end
-    if self.options.icon_color_highlight then
+    if self.options.icon_color_highlight and type(self.options.icon) == 'table' and self.options.icon.align == 'right' then
+      self.status = table.concat {
+        self.status,
+        ' ',
+        self:format_hl(self.options.icon_color_highlight),
+        icon,
+        self:get_default_hl(),
+      }
+    elseif self.options.icon_color_highlight then
       self.status = table.concat {
         self:format_hl(self.options.icon_color_highlight),
         icon,
@@ -123,6 +131,8 @@ function M:apply_icon()
         ' ',
         self.status,
       }
+    elseif type(self.options.icon) == 'table' and self.options.icon.align == 'right' then
+      self.status = table.concat({ self.status, icon }, ' ')
     else
       self.status = table.concat({ icon, self.status }, ' ')
     end

lua/lualine/components/filetype.lua

@@ -61,6 +61,8 @@ function M:apply_icon()
 
   if self.options.icon_only then
     self.status = icon
+  elseif type(self.options.icon) == 'table' and self.options.icon.align == 'right' then
+    self.status = self.status .. ' ' .. icon
   else
     self.status = icon .. ' ' .. self.status
   end

tests/spec/component_spec.lua

@@ -361,6 +361,24 @@ describe('Filetype component', function()
     assert_component('filetype', opts, '*')
     package.loaded['nvim-web-devicons'] = nil
   end)
+
+  it('displays right aligned icon when icon.align is "right"', function()
+    package.loaded['nvim-web-devicons'] = {
+      get_icon = function()
+        return '*', 'test_highlight_group'
+      end,
+    }
+
+    local opts = build_component_opts {
+      component_separators = { left = '', right = '' },
+      padding = 0,
+      colored = false,
+      icon_only = false,
+      icon = { align = 'right' }
+    }
+    assert_component('filetype', opts, 'lua *')
+    package.loaded['nvim-web-devicons'] = nil
+  end)
 end)
 
 describe('Hostname component', function()