Add handle_body/1 callback to EEx.Engine

Author: ericmj

lib/eex/lib/eex/compiler.ex

@@ -51,8 +51,8 @@ defmodule EEx.Compiler do
     raise EEx.SyntaxError, message: "unexpected token: #{inspect chars} at line #{inspect line}"
   end
 
-  defp generate_buffer([], buffer, [], _state) do
-    buffer
+  defp generate_buffer([], buffer, [], state) do
+    state.engine.handle_body(buffer)
   end
 
   defp generate_buffer([], _buffer, _scope, _state) do

lib/eex/lib/eex/engine.ex

@@ -1,7 +1,11 @@
 defmodule EEx.Engine do
   @moduledoc ~S"""
   This is the basic EEx engine that ships with Elixir.
-  An engine needs to implement two functions:
+  An engine needs to implement three functions:
+
+  * `handle_body(quoted)` - receives the final built quoted
+    expression, should do final post-processing and return a
+    quoted expression;
 
   * `handle_text(buffer, text)` - it receives the buffer,
     the text and must return a new quoted expression;
@@ -22,9 +26,18 @@ defmodule EEx.Engine do
 
   use Behaviour
 
+  defcallback handle_body(Macro.t) :: Macro.t
   defcallback handle_text(Macro.t, binary) :: Macro.t
   defcallback handle_expr(Macro.t, binary, Macro.t) :: Macro.t
 
+  @doc """
+  The default implementation implementation simply returns the
+  given expression.
+  """
+  def handle_body(quoted) do
+    quoted
+  end
+
   @doc """
   The default implementation simply concatenates text to the buffer.
   """
@@ -54,4 +67,4 @@ defmodule EEx.Engine do
       tmp
     end
   end
-end
+end

lib/eex/lib/eex/smart_engine.ex

@@ -15,6 +15,10 @@ defmodule EEx.TransformerEngine do
     quote do
       @behaviour EEx.Engine
 
+      def handle_body(body) do
+        EEx.Engine.handle_body(body)
+      end
+
       def handle_text(buffer, text) do
         EEx.Engine.handle_text(buffer, text)
       end
@@ -39,7 +43,7 @@ defmodule EEx.TransformerEngine do
         other
       end
 
-      defoverridable [transform: 1, handle_expr: 3, handle_text: 2]
+      defoverridable [transform: 1, handle_body: 1, handle_expr: 3, handle_text: 2]
     end
   end
 end

lib/eex/test/eex_test.exs

@@ -344,6 +344,26 @@ foo
       }
   end
 
+  defmodule TestEngine do
+    @behaviour EEx.Engine
+
+    def handle_body(body) do
+      { :wrapped, body }
+    end
+
+    def handle_text(buffer, text) do
+      EEx.Engine.handle_text(buffer, text)
+    end
+
+    def handle_expr(buffer, mark, expr) do
+      EEx.Engine.handle_expr(buffer, mark, expr)
+    end
+  end
+
+  test "calls handle_body" do
+    assert { :wrapped, "foo" } = EEx.eval_string("foo", [], engine: TestEngine)
+  end
+
   defp assert_eval(expected, actual) do
     result = EEx.eval_string(actual, [], file: __ENV__.file, engine: EEx.Engine)
     assert result == expected