Refactor small things here and there

lib/mint/core/util.ex

@@ -114,6 +114,16 @@ defmodule Mint.Core.Util do
   def maybe_concat(<<>>, data), do: data
   def maybe_concat(buffer, data) when is_binary(buffer), do: buffer <> data
 
+  @spec lower_header_name(String.t()) :: String.t()
+  def lower_header_name(name) do
+    String.downcase(name, :ascii)
+  end
+
+  @spec lower_header_keys(Types.headers()) :: Types.headers()
+  def lower_header_keys(headers) do
+    :lists.map(fn {name, value} -> {lower_header_name(name), value} end, headers)
+  end
+
   @spec find_unallowed_trailer_header(Types.headers()) :: {String.t(), String.t()} | nil
   def find_unallowed_trailer_header(headers) do
     Enum.find(headers, fn {name, _value} -> name in @unallowed_trailer_headers end)

lib/mint/http1.ex

@@ -972,10 +972,6 @@ defmodule Mint.HTTP1 do
     }
   end
 
-  defp lower_header_keys(headers) do
-    for {name, value} <- headers, do: {String.downcase(name, :ascii), value}
-  end
-
   defp add_default_headers(headers, conn) do
     headers
     |> Util.put_new_header("user-agent", @user_agent)

lib/mint/http1/parse.ex

@@ -1,8 +1,6 @@
 defmodule Mint.HTTP1.Parse do
   @moduledoc false
 
-  alias Mint.Core.Util
-
   defmacro is_digit(char), do: quote(do: unquote(char) in ?0..?9)
   defmacro is_alpha(char), do: quote(do: unquote(char) in ?a..?z or unquote(char) in ?A..?Z)
   defmacro is_whitespace(char), do: quote(do: unquote(char) in ~c"\s\t")

lib/mint/http1/response.ex

@@ -1,8 +1,6 @@
 defmodule Mint.HTTP1.Response do
   @moduledoc false
 
-  alias Mint.Core.Util
-
   def decode_status_line(binary) do
     case :erlang.decode_packet(:http_bin, binary, []) do
       {:ok, {:http_response, version, status, reason}, rest} ->
@@ -38,11 +36,6 @@ defmodule Mint.HTTP1.Response do
     end
   end
 
-  defp header_name(atom) when is_atom(atom) do
-    atom
-    |> Atom.to_string()
-    |> String.downcase(:ascii)
-  end
-
-  defp header_name(binary) when is_binary(binary), do: String.downcase(binary, :ascii)
+  defp header_name(atom) when is_atom(atom), do: atom |> Atom.to_string() |> header_name()
+  defp header_name(binary) when is_binary(binary), do: Mint.Core.Util.lower_header_name(binary)
 end

lib/mint/http2.ex

@@ -521,7 +521,7 @@ defmodule Mint.HTTP2 do
       when is_binary(method) and is_binary(path) and is_list(headers) do
     headers =
       headers
-      |> downcase_header_names()
+      |> lower_header_keys()
       |> add_pseudo_headers(conn, method, path)
       |> add_default_headers(body)
       |> sort_pseudo_headers_to_front()
@@ -1108,7 +1108,7 @@ defmodule Mint.HTTP2 do
   end
 
   defp encode_stream_body_request_payload(conn, stream_id, {:eof, trailer_headers}) do
-    lowered_headers = downcase_header_names(trailer_headers)
+    lowered_headers = lower_header_keys(trailer_headers)
 
     if unallowed_trailer_header = Util.find_unallowed_trailer_header(lowered_headers) do
       error = wrap_error({:unallowed_trailing_header, unallowed_trailer_header})
@@ -1344,10 +1344,6 @@ defmodule Mint.HTTP2 do
     end)
   end
 
-  defp downcase_header_names(headers) do
-    for {name, value} <- headers, do: {String.downcase(name, :ascii), value}
-  end
-
   defp add_default_headers(headers, body) do
     headers
     |> Util.put_new_header("user-agent", @user_agent)
@@ -1746,7 +1742,7 @@ defmodule Mint.HTTP2 do
 
   defp join_cookie_headers(headers) do
     # If we have 0 or 1 Cookie headers, we just use the old list of headers.
-    case Enum.split_with(headers, fn {name, _value} -> String.downcase(name, :ascii) == "cookie" end) do
+    case Enum.split_with(headers, fn {name, _value} -> lower_header_name(name) == "cookie" end) do
       {[], _headers} ->
         headers
 

pages/Decompression.md

@@ -31,7 +31,7 @@ We need to attempt to decompress the data if the `content-encoding` header is pr
 defp get_content_encoding_header(headers) do
   headers
   |> Enum.flat_map([], fn {name, value} ->
-    if String.downcase(name) == "content-encoding" do
+    if String.downcase(name, :ascii) == "content-encoding" do
       value
       |> String.downcase()
       |> String.split(",", trim: true)