lib/phoenix/template/eex_engine.ex

defmodule Phoenix.Template.EExEngine do
  @moduledoc """
  The Phoenix engine that handles the `.eex` extension.
  """

  @behaviour Phoenix.Template.Engine

  def compile(path, _name) do
    EEx.compile_file(path, [line: 1] ++ options_for(path))
  end

  defp options_for(path) do
    "." <> format = path |> Path.rootname() |> Path.extname()

    case Phoenix.Template.format_encoder(format) do
      Phoenix.HTML.Engine ->
        unless Code.ensure_loaded?(Phoenix.HTML.Engine) do
          raise "could not load Phoenix.HTML.Engine to use with .html.eex templates. " <>
                  "You can configure your own format encoder for HTML but we recommend " <>
                  "adding phoenix_html as a dependency as it provides XSS protection."
        end

        trim =
          case Application.get_env(:phoenix_template, :trim_on_html_eex_engine) do
            nil ->
              case Application.get_env(:phoenix_view, :trim_on_html_eex_engine) do
                nil ->
                  Application.get_env(:phoenix, :trim_on_html_eex_engine, true)

                boolean ->
                  IO.warn(
                    "config :phoenix_view, :trim_on_html_eex_engine is deprecated, please use config :phoenix_template, :trim_on_html_eex_engine instead"
                  )

                  boolean
              end

            boolean ->
              boolean
          end

        [engine: Phoenix.HTML.Engine, trim: trim]

      _ ->
        [engine: EEx.SmartEngine]
    end
  end
end