Merge pull request #48 from ukutaht/support_multiple_placeholders

Support multiple placeholders

lib/ast_mangler.ex

@@ -1,8 +0,0 @@
-defmodule ASTMangler do
-  def expand(ast, replacement) do
-    Macro.prewalk(ast, fn(node) -> update(node, replacement) end)
-  end
-
-  def update(:__, replacement), do: replacement
-  def update(node, _), do: node
-end

lib/blanks.ex

@@ -0,0 +1,21 @@
+defmodule Blanks do
+  def replace(ast, replacement) when not is_list(replacement), do: replace(ast, [replacement])
+  def replace([do: ast], replacements), do: [do: replace(ast, replacements)]
+  def replace(ast, replacements) do
+    ast
+    |> Macro.prewalk(replacements, &pre/2)
+    |> elem(0)
+  end
+
+  defp pre(:__, [first | remainder]), do: {first, remainder}
+  defp pre(node, acc), do: {node, acc}
+
+  def count(ast) do
+    ast
+    |> Macro.prewalk(0, &count/2)
+    |> elem(1)
+  end
+
+  defp count(:__, acc), do: {node, acc+1}
+  defp count(node, acc), do: {node, acc}
+end

lib/koans.ex

@@ -1,9 +1,12 @@
 defmodule Koans do
   defmacro koan(name, body) do
     compiled_name = String.to_atom(name)
-    mangled_body = ASTMangler.expand(body, quote do: answer)
+    number_of_args = Blanks.count(body)
     quote do
       @koans unquote(compiled_name)
+
+      generate_test_method(unquote(compiled_name), unquote(number_of_args), unquote(body))
+
       def unquote(compiled_name)() do
         try do
           unquote(body)
@@ -12,13 +15,35 @@ defmodule Koans do
           e in _ -> e
         end
       end
+    end
+  end
 
-      def unquote(compiled_name)(answer) do
-        unquote(mangled_body)
+  defmacro generate_test_method(_name, 0, _body), do: false
+  defmacro generate_test_method(name, 1, body) do
+    single_var = Blanks.replace(body, Macro.var(:answer, Koans))
+    quote do
+      def unquote(name)(answer) do
+        converted = {answer}
+        unquote(single_var)
         :ok
       end
     end
   end
+  defmacro generate_test_method(name, number_of_args, body) do
+    answer_placeholders = create_vars(number_of_args)
+    multi_var = Blanks.replace(body, answer_placeholders)
+    quote do
+      def unquote(name)({:multiple, answers}) do
+        converted = List.to_tuple(answers)
+        unquote(multi_var)
+        :ok
+      end
+    end
+  end
+
+  defp create_vars(amount) do
+    Enum.map(0..amount, fn (idx) -> quote do: elem(converted, unquote(idx)) end)
+  end
 
   defmacro __using__(_opts) do
     quote do

lib/koans/12_task.ex

@@ -8,7 +8,8 @@ defmodule Tasks do
   end
 
   koan "if you don't need a result, use start_link/1" do
-    {:ok, _pid} = Task.start_link(fn -> 1+1 end)
+    {result, _pid} = Task.start_link(fn -> 1+1 end)
+    assert result == :__
   end
 
   koan "yield returns nothing if the task isn't done yet" do

test/ast_mangler_test.exs

@@ -1,31 +0,0 @@
-defmodule ASTManglerTest do
-  use ExUnit.Case, async: true
-
-  test "simple replacement" do
-    ast = quote do: 1 + :__
-
-    mangled = ASTMangler.expand(ast, 37)
-    assert {:+, [context: ASTManglerTest, import: Kernel], [1, 37]} == mangled
-  end
-
-  def complex_example do
-    [head | tail] = [1,2,3,4]
-
-    assert head == 1
-    assert tail == [2,3,4]
-  end
-
-  def foo(answer) do
-    if answer == :yes do
-      :bar
-    else
-      :batz
-    end
-  end
-
-  test "complex example" do
-    ast = [do: {:assert, [line: 5], [{:==, [line: 5], [true, :__]}]}]
-
-    assert [do: {:assert, [line: 5], [{:==, [line: 5], [true, true]}]}] == ASTMangler.expand(ast, true)
-  end
-end

test/blanks_test.exs

@@ -0,0 +1,54 @@
+defmodule BlanksTest do
+  use ExUnit.Case, async: true
+
+  test "simple replacement" do
+    ast = quote do: 1 + :__
+
+    mangled = Blanks.replace(ast, 37)
+    assert {:+, [context: BlanksTest, import: Kernel], [1, 37]} == mangled
+  end
+
+  test "Work with multiple different replacements" do
+    [koan | _] = SampleKoan.all_koans
+    assert :ok == apply(SampleKoan, koan, [{:multiple, [3,4]}])
+  end
+
+  def complex_example do
+    [head | tail] = [1,2,3,4]
+
+    assert head == 1
+    assert tail == [2,3,4]
+  end
+
+  def foo(answer) do
+    if answer == :yes do
+      :bar
+    else
+      :batz
+    end
+  end
+
+  test "complex example" do
+    ast = [do: {:assert, [line: 5], [{:==, [line: 5], [true, :__]}]}]
+
+    assert [do: {:assert, [line: 5], [{:==, [line: 5], [true, true]}]}] == Blanks.replace(ast, true)
+  end
+
+  test "multiple arguments" do
+    ast = [do: {:assert, [line: 5], [{:==, [line: 5], [:__, :__]}]}]
+
+    assert [do: {:assert, [line: 5], [{:==, [line: 5], [true, false]}]}] == Blanks.replace(ast, [true, false])
+  end
+
+  test "counts simple blanks" do
+    ast = quote do: 1 + :__
+
+    assert Blanks.count(ast) == 1
+  end
+
+  test "counts multiple blanks" do
+    ast = [do: {:assert, [line: 5], [{:==, [line: 5], [:__, :__]}]}]
+
+    assert Blanks.count(ast) == 2
+  end
+end

test/koans_harness_test.exs

@@ -222,7 +222,7 @@ defmodule KoansHarnessTest do
   test "Tasks" do
     answers = [
       10,
-      :todo,
+      :ok,
       nil,
       nil,
       9,

test/sample_koan_test.exs

@@ -0,0 +1,8 @@
+defmodule SampleKoan do
+  use Koans
+
+  koan "thinking more than once" do
+    assert 3 == :__
+    assert 4 == :__
+  end
+end