Add down for simple markdown

Author: RoyalIcing

apps/components_guide_web/lib/components_guide_web/views/down_view.ex

@@ -0,0 +1,52 @@
+defmodule ComponentsGuideWeb.DownView do
+  use ComponentsGuideWeb, :view
+
+  defmodule ParserState do
+    defstruct bold: false, italics: false, html: []
+
+    @spec parse(binary) ::
+            {:safe,
+             binary
+             | maybe_improper_list(
+                 binary | maybe_improper_list(any, binary | []) | byte,
+                 binary | []
+               )}
+    def parse(input) when is_binary(input) do
+      next(%__MODULE__{}, input)
+    end
+
+    defp next(state = %__MODULE__{italics: true}, <<"_"::utf8>> <> rest) do
+      %__MODULE__{state | html: [state.html], italics: false}
+      |> next(rest)
+    end
+
+    defp next(state = %__MODULE__{italics: false}, <<"_"::utf8>> <> rest) do
+      %__MODULE__{state | html: ["<em1>" | state.html], italics: true}
+      |> next(rest)
+    end
+
+    defp next(state = %__MODULE__{}, <<char::utf8>> <> rest) do
+      %__MODULE__{state | html: [<<char::utf8>> | state.html]}
+      |> next(rest)
+    end
+
+    defp next(state = %__MODULE__{italics: italics}, "") do
+      html = Enum.reverse(state.html) |> Enum.join()
+
+      html =
+        case italics do
+          true ->
+            html <> "</em>"
+
+          false ->
+            html
+        end
+
+      Phoenix.HTML.raw(html)
+    end
+  end
+
+  def down(input) when is_binary(input) do
+    ParserState.parse(input)
+  end
+end

apps/components_guide_web/test/collected_live_web/views/down_view_test.exs

@@ -0,0 +1,16 @@
+defmodule ComponentsGuideWeb.DownViewTest do
+  use ComponentsGuideWeb.ConnCase, async: true
+
+  alias ComponentsGuideWeb.DownView, as: Subject
+  use Phoenix.HTML
+
+  describe "humanize_bytes/1" do
+    test "plain text" do
+      assert Subject.down("plain text") == raw("plain text")
+    end
+
+    test "italics" do
+      assert Subject.down("plain _text_") == raw("plain <em>text</em>")
+    end
+  end
+end