feat: add sort_by "suffix"

doc/nvim-tree-lua.txt

@@ -568,8 +568,10 @@ Reloads the explorer every time a buffer is written to.
 
 *nvim-tree.sort_by*
 Changes how files within the same directory are sorted.
-Can be one of `name`, `case_sensitive`, `modification_time`, `extension`,
-`filetype` or a function.
+Can be one of `"name"`, `"case_sensitive"`, `"modification_time"`, `"extension"`,
+`"suffix"`, `"filetype"` or a function.
+`"extension"` uses all suffixes e.g. `foo.tar.gz` -> `.tar.gz`
+`"suffix"` uses the last e.g. `.gz`
   Type: `string` | `function(nodes)`, Default: `"name"`
 
   Function may perform a sort or return a string with one of the above

lua/nvim-tree/explorer/sorters.lua

@@ -168,6 +168,56 @@ function C.modification_time(a, b)
   return last_modified_b <= last_modified_a
 end
 
+function C.suffix(a, b)
+  if not (a and b) then
+    return true
+  end
+
+  -- directories go first
+  if a.nodes and not b.nodes then
+    return true
+  elseif not a.nodes and b.nodes then
+    return false
+  elseif a.nodes and b.nodes then
+    return C.name(a, b)
+  end
+
+  -- dotfiles go second
+  if a.name:sub(1, 1) == "." and b.name:sub(1, 1) ~= "." then
+    return true
+  elseif a.name:sub(1, 1) ~= "." and b.name:sub(1, 1) == "." then
+    return false
+  elseif a.name:sub(1, 1) == "." and b.name:sub(1, 1) == "." then
+    return C.name(a, b)
+  end
+
+  -- unsuffixed go third
+  local a_suffix_ndx = a.name:find "%.%w+$"
+  local b_suffix_ndx = b.name:find "%.%w+$"
+
+  if not a_suffix_ndx and b_suffix_ndx then
+    return true
+  elseif a_suffix_ndx and not b_suffix_ndx then
+    return false
+  elseif not (a_suffix_ndx and b_suffix_ndx) then
+    return C.name(a, b)
+  end
+
+  -- finally, compare by suffixes
+  local a_suffix = a.name:sub(a_suffix_ndx)
+  local b_suffix = b.name:sub(b_suffix_ndx)
+
+  if a_suffix and not b_suffix then
+    return true
+  elseif not a_suffix and b_suffix then
+    return false
+  elseif a_suffix:lower() == b_suffix:lower() then
+    return C.name(a, b)
+  end
+
+  return a_suffix:lower() < b_suffix:lower()
+end
+
 function C.extension(a, b)
   if not (a and b) then
     return true