add Zipper.prepend/append_siblings

lib/style/blocks.ex

@@ -132,8 +132,9 @@ defmodule Styler.Style.Blocks do
         cond do
           Enum.any?(preroll) ->
             # put the preroll before the with statement in either a block we create or the existing parent block
-            preroll
-            |> Enum.reduce(Style.ensure_block_parent(zipper), &Zipper.insert_left(&2, &1))
+            zipper
+            |> Style.ensure_block_parent()
+            |> Zipper.prepend_siblings(preroll)
             |> run(ctx)
 
           Enum.any?(postroll) ->
@@ -189,8 +190,8 @@ defmodule Styler.Style.Blocks do
         Zipper.update(zipper, fn {:with, meta, _} -> {:__block__, Keyword.take(meta, [:line]), block} end)
 
       {{:__block__, _, _}, _} ->
-        block
-        |> Enum.reduce(zipper, &Zipper.insert_left(&2, &1))
+        zipper
+        |> Zipper.prepend_siblings(block)
         |> Zipper.remove()
 
       {ast, _} ->

lib/style/module_directives.ex

@@ -180,13 +180,11 @@ defmodule Styler.Style.ModuleDirectives do
         Zipper.update(parent, &Zipper.replace_children(&1, directives))
 
       true ->
-        {last_directive, meta} =
-          parent
-          |> Zipper.update(&Zipper.replace_children(&1, directives))
-          |> Zipper.down()
-          |> Zipper.rightmost()
-
-        {last_directive, %{meta | r: nondirectives}}
+        parent
+        |> Zipper.update(&Zipper.replace_children(&1, directives))
+        |> Zipper.down()
+        |> Zipper.rightmost()
+        |> Zipper.append_siblings(nondirectives)
     end
   end
 

lib/zipper.ex

@@ -173,6 +173,17 @@ defmodule Styler.Zipper do
   def insert_left({_, nil}, _), do: raise(ArgumentError, message: "Can't insert siblings at the top level.")
   def insert_left({tree, meta}, child), do: {tree, %{meta | l: [child | meta.l]}}
 
+  @doc """
+  Inserts many siblings to the left.
+
+  Equivalent to
+
+      Enum.reduce(siblings, zipper, &Zipper.insert_left(&2, &1))
+  """
+  @spec prepend_siblings(zipper, [tree]) :: zipper
+  def prepend_siblings({_, nil}, _), do: raise(ArgumentError, message: "Can't insert siblings at the top level.")
+  def prepend_siblings({tree, meta}, siblings), do: {tree, %{meta | l: Enum.reverse(siblings, meta.l)}}
+
   @doc """
   Inserts the item as the right sibling of the node at this zipper, without
   moving. Raises an `ArgumentError` when attempting to insert a sibling at the
@@ -182,6 +193,17 @@ defmodule Styler.Zipper do
   def insert_right({_, nil}, _), do: raise(ArgumentError, message: "Can't insert siblings at the top level.")
   def insert_right({tree, meta}, child), do: {tree, %{meta | r: [child | meta.r]}}
 
+  @doc """
+  Inserts many siblings to the right.
+
+  Equivalent to
+
+      Enum.reduce(siblings, zipper, &Zipper.insert_right(&2, &1))
+  """
+  @spec append_siblings(zipper, [tree]) :: zipper
+  def append_siblings({_, nil}, _), do: raise(ArgumentError, message: "Can't insert siblings at the top level.")
+  def append_siblings({tree, meta}, siblings), do: {tree, %{meta | r: siblings ++ meta.r}}
+
   @doc """
   Inserts the item as the leftmost child of the node at this zipper,
   without moving.