Clear functions (#71)

lib/rhai/ast.ex

@@ -96,6 +96,16 @@ defmodule Rhai.AST do
     |> wrap_resource()
   end
 
+  @doc """
+  Clear all function definitions in the AST.
+  """
+  @spec clear_functions(t()) :: t()
+  def clear_functions(%__MODULE__{resource: resource} = ast) do
+    Rhai.Native.ast_clear_functions(resource)
+
+    ast
+  end
+
   @doc false
   def wrap_resource(resource) do
     %__MODULE__{

lib/rhai/native.ex

@@ -98,6 +98,7 @@ defmodule Rhai.Native do
   def ast_clear_source(_ast), do: err()
   def ast_merge(_ast, _other), do: err()
   def ast_combine(_ast, _other), do: err()
+  def ast_clear_functions(_ast), do: err()
 
   defp err, do: :erlang.nif_error(:nif_not_loaded)
 end

native/rhai_rustler/src/ast.rs

@@ -60,3 +60,10 @@ fn ast_combine(
         ast: Mutex::new(ast.combine(other_ast).clone()),
     })
 }
+
+#[rustler::nif]
+fn ast_clear_functions(resource: ResourceArc<ASTResource>) {
+    let mut ast = resource.ast.try_lock().unwrap();
+
+    ast.clear_functions();
+}

native/rhai_rustler/src/lib.rs

@@ -130,7 +130,8 @@ rustler::init!(
         ast_set_source,
         ast_clear_source,
         ast_merge,
-        ast_combine
+        ast_combine,
+        ast_clear_functions,
     ],
     load = load
 );

test/rhai/ast_test.exs

@@ -74,4 +74,23 @@ defmodule Rhai.ASTTest do
                Engine.eval_ast(engine, ast3)
     end
   end
+
+  describe "clear_functions/1" do
+    test "should clear all functions" do
+      engine = Engine.new()
+
+      {:ok, ast} =
+        Engine.compile(engine, """
+        fn foo(x) { 42 + x }
+        foo(1)
+        """)
+
+      assert {:ok, 43} ==
+               Engine.eval_ast(engine, ast)
+
+      ast = AST.clear_functions(ast)
+
+      assert {:error, {:function_not_found, _}} = Engine.eval_ast(engine, ast)
+    end
+  end
 end