refacto: move filters and sorters in their own modules

Also exclude filters is taken into account in git ignore
fixes #892

lua/nvim-tree/explorer/sorters.lua

@@ -0,0 +1,122 @@
+local M = {
+  sort_by = nil,
+  node_comparator = nil,
+}
+
+---Create a shallow copy of a portion of a list.
+---@param t table
+---@param first integer First index, inclusive
+---@param last integer Last index, inclusive
+---@return table
+local function tbl_slice(t, first, last)
+  local slice = {}
+  for i = first, last or #t, 1 do
+    table.insert(slice, t[i])
+  end
+
+  return slice
+end
+
+local function merge(t, first, mid, last, comparator)
+  local n1 = mid - first + 1
+  local n2 = last - mid
+  local ls = tbl_slice(t, first, mid)
+  local rs = tbl_slice(t, mid + 1, last)
+  local i = 1
+  local j = 1
+  local k = first
+
+  while (i <= n1 and j <= n2) do
+    if comparator(ls[i], rs[j]) then
+      t[k] = ls[i]
+      i = i + 1
+    else
+      t[k] = rs[j]
+      j = j + 1
+    end
+    k = k + 1
+  end
+
+  while i <= n1 do
+    t[k] = ls[i]
+    i = i + 1
+    k = k + 1
+  end
+
+  while j <= n2 do
+    t[k] = rs[j]
+    j = j + 1
+    k = k + 1
+  end
+end
+
+local function split_merge(t, first, last, comparator)
+  if (last - first) < 1 then return end
+
+  local mid = math.floor((first + last) / 2)
+
+  split_merge(t, first, mid, comparator)
+  split_merge(t, mid + 1, last, comparator)
+  merge(t, first, mid, last, comparator)
+end
+
+---Perform a merge sort on a given list.
+---@param t any[]
+---@param comparator function|nil
+function M.merge_sort(t, comparator)
+  if not comparator then
+    comparator = function (left, right)
+      return left < right
+    end
+  end
+
+  split_merge(t, 1, #t, comparator)
+end
+
+function M.node_comparator_name(a, b)
+  if not (a and b) then
+    return true
+  end
+  if a.nodes and not b.nodes then
+    return true
+  elseif not a.nodes and b.nodes then
+    return false
+  end
+
+  return a.name:lower() <= b.name:lower()
+end
+
+function M.node_comparator_modification_time(a, b)
+  if not (a and b) then
+    return true
+  end
+  if a.nodes and not b.nodes then
+    return true
+  elseif not a.nodes and b.nodes then
+    return false
+  end
+
+  local last_modified_a = 0
+  local last_modified_b = 0
+
+  if a.fs_stat ~= nil then
+    last_modified_a = a.fs_stat.mtime.sec
+  end
+
+  if b.fs_stat ~= nil then
+    last_modified_b = b.fs_stat.mtime.sec
+  end
+
+  return last_modified_a <= last_modified_b
+end
+
+function M.setup(opts)
+  M.sort_by = opts.sort_by
+  if M.sort_by == "modification_time" then
+    M.node_comparator = M.node_comparator_modification_time
+  else
+    M.node_comparator = M.node_comparator_name
+  end
+end
+
+return M