Introduce URI.encode_www_form/1 function

Author: lexmag

lib/elixir/lib/uri.ex

@@ -142,7 +142,8 @@ defmodule URI do
   end
 
   defp pair({k, v}) do
-    encode(to_string(k)) <> "=" <> encode(to_string(v))
+    encode_www_form(to_string(k)) <>
+    "=" <> encode_www_form(to_string(v))
   end
 
   @doc """
@@ -154,7 +155,6 @@ defmodule URI do
     c in ':/?#[]@!$&\'()*+,;='
   end
 
-  #
   @doc """
   Checks if the character is a "unreserved" character in a URI.
 
@@ -191,6 +191,24 @@ defmodule URI do
     for <<c <- str>>, into: "", do: percent(c, predicate)
   end
 
+  @doc """
+  Encode a string as "x-www-urlencoded".
+
+  ## Example
+
+      iex> URI.encode_www_form("put: it+й")
+      "put%3A+it%2B%D0%B9"
+
+  """
+  def encode_www_form(str) do
+    for <<c <- str>>, into: "" do
+      case percent(c, &char_unreserved?/1) do
+        "%20" -> "+"
+        pct   -> pct
+      end
+    end
+  end
+
   defp percent(c, predicate) do
     if predicate.(c) do
       <<c>>

lib/elixir/test/elixir/uri_test.exs

@@ -9,10 +9,16 @@ defmodule URITest do
            "%0D%0A%26%3C%25%3E%22%20%E3%82%86"
   end
 
+  test :encode_www_form do
+    assert URI.encode_www_form("4test ~1.x") == "4test+~1.x"
+    assert URI.encode_www_form("poll:146%") == "poll%3A146%25"
+    assert URI.encode_www_form("/\n+/ゆ") == "%2F%0A%2B%2F%E3%82%86"
+  end
+
   test :encode_query do
     assert URI.encode_query([{:foo, :bar}, {:baz, :quux}]) == "foo=bar&baz=quux"
     assert URI.encode_query([{"foo", "bar"}, {"baz", "quux"}]) == "foo=bar&baz=quux"
-    assert URI.encode_query([{"foo", :bar}]) == "foo=bar"
+    assert URI.encode_query([{"foo z", :bar}]) == "foo+z=bar"
 
     assert_raise ArgumentError, fn ->
       URI.encode_query([{"foo", 'bar'}])