feat: case-insentive sorting (#598)

* feat(config): `ignore_case` option

* feat(api): provide configured sort case converter in `with_pin_order`

This seems like the cleanest way to inject the conversion. We don't know
what is applicable to be converted from within the function, and so we
can't apply it automatically. On the other hand, if we make this a
separate helper function, it will be cumbersome to call it in each
sorting function that needs it.

I would be open to hearing other ideas, though.

* ref(api): use `to_sort_case` in sorting functions where applicable

* docs: `sort.ignore_case`

* perf(api): use function instead of closure

SEE: #598 (comment)

README.md

@@ -401,6 +401,12 @@ require'barbar'.setup {
   -- Sets the name of unnamed buffers. By default format is "[Buffer X]"
   -- where X is the buffer number. But only a static string is accepted here.
   no_name_title = nil,
+
+  -- sorting options
+  sort = {
+    -- tells barbar to ignore case differences while sorting buffers
+    ignore_case = true,
+  },
 }
 ```
 

doc/barbar.txt

@@ -535,6 +535,16 @@ sidebar_filetypes ~
     }}
 <
 
+                                                             *barbar-setup.sort*
+sort ~
+  Configures the `:BufferOrderBy*` commands.
+
+                                                 *barbar-setup.sort.ignore_case*
+  sort.ignore_case ~
+    `boolean` (default `false`)
+    If `true`, comparisons of names in buffer orderings will not take into
+    account differences in case (e.g. 'a' will equal 'A').
+
                                                          *barbar-setup.tabpages*
 tabpages ~
   `boolean`  (default: `true`)

lua/barbar/api.lua

@@ -13,6 +13,7 @@ local command = vim.api.nvim_command --- @type function
 local get_current_buf = vim.api.nvim_get_current_buf --- @type function
 local getchar = vim.fn.getchar --- @type function
 local set_current_buf = vim.api.nvim_set_current_buf --- @type function
+local tolower = vim.fn.tolower
 
 -- TODO: remove `vim.fs and` after 0.8 release
 local normalize = vim.fs and vim.fs.normalize
@@ -59,9 +60,13 @@ local function notify_buffer_not_found(buffer_number)
 end
 
 --- Forwards some `order_func` after ensuring that all buffers sorted in the order of pinned first.
---- @param order_func fun(bufnr_a: integer, bufnr_b: integer): boolean accepts `(integer, integer)` params.
+--- @param order_func fun(bufnr_a: integer, bufnr_b: integer, to_sort_case: fun(s: string): string): boolean accepts `(integer, integer)` params.
 --- @return fun(bufnr_a: integer, bufnr_b: integer): boolean
 local function with_pin_order(order_func)
+  local to_sort_case = config.options.sort.ignore_case and tolower or function(s)
+    return s
+  end
+
   return function(a, b)
     local a_pinned = state.is_pinned(a)
     local b_pinned = state.is_pinned(b)
@@ -71,7 +76,7 @@ local function with_pin_order(order_func)
     elseif b_pinned and not a_pinned then
       return false
     else
-      return order_func(a, b)
+      return order_func(a, b, to_sort_case)
     end
   end
 end
@@ -364,12 +369,12 @@ end
 --- Order the buffers by their name
 --- @return nil
 function api.order_by_name()
-  table_sort(state.buffers, with_pin_order(function(a, b)
+  table_sort(state.buffers, with_pin_order(function(a, b, to_sort_case)
     local parts_of_a = vim.split(buf_get_name(a), '/')
     local parts_of_b = vim.split(buf_get_name(b), '/')
     local name_of_a = parts_of_a[#parts_of_a]
     local name_of_b = parts_of_b[#parts_of_b]
-    return name_of_b > name_of_a
+    return to_sort_case(name_of_b) > to_sort_case(name_of_a)
   end))
 
   render.update()
@@ -378,10 +383,10 @@ end
 --- Order the buffers by their parent directory.
 --- @return nil
 function api.order_by_directory()
-  table_sort(state.buffers, with_pin_order(function(a, b)
+  table_sort(state.buffers, with_pin_order(function(a, b, to_sort_case)
     local name_of_a = buf_get_name(a)
     local name_of_b = buf_get_name(b)
-    local compare_a_b = name_of_b > name_of_a
+    local compare_a_b = to_sort_case(name_of_b) > to_sort_case(name_of_a)
 
     -- TODO: remove this block after 0.8 releases
     if not normalize then
@@ -409,8 +414,8 @@ end
 --- Order the buffers by filetype.
 --- @return nil
 function api.order_by_language()
-  table_sort(state.buffers, with_pin_order(function(a, b)
-    return buf_get_option(a, 'filetype') < buf_get_option(b, 'filetype')
+  table_sort(state.buffers, with_pin_order(function(a, b, to_sort_case)
+    return to_sort_case(buf_get_option(a, 'filetype')) < to_sort_case(buf_get_option(b, 'filetype'))
   end))
 
   render.update()

lua/barbar/config.lua

@@ -194,6 +194,9 @@ local DEPRECATED_OPTIONS = {
 --- @field event? string
 --- @field text? string
 
+--- @class barbar.config.options.sort
+--- @field ignore_case boolean
+
 --- @class barbar.config.options
 --- @field animation boolean
 --- @field auto_hide integer
@@ -216,6 +219,7 @@ local DEPRECATED_OPTIONS = {
 --- @field no_name_title? string
 --- @field semantic_letters boolean
 --- @field sidebar_filetypes {[string]: nil|barbar.config.options.sidebar_filetype}
+--- @field sort barbar.config.options.sort
 --- @field tabpages boolean
 
 --- @class barbar.Config
@@ -341,6 +345,7 @@ function config.setup(options)
     preset = 'default',
     semantic_letters = true,
     sidebar_filetypes = {},
+    sort = { ignore_case = false },
     tabpages = true,
   })