--- a/src/pt-loop.cc
+++ b/src/pt-loop.cc
@@ -115,6 +115,92 @@
   tw.visit_while_command (*this);
 }
 
+// Do-While
+
+void
+tree_do_while_command::eval (void)
+{
+  if (error_state)
+    return;
+
+  if (! expr)
+    panic_impossible ();
+
+  for (;;)
+    {
+      if (list)
+	{
+	  list->eval ();
+
+	  if (error_state)
+	    {
+	      eval_error ();
+	      return;
+	    }
+	}
+
+      if (quit_loop_now () || ! expr->is_logically_true ("do-while"))
+	break;
+    }
+}
+
+void
+tree_do_while_command::eval_error (void)
+{
+  if (error_state > 0)
+    ::error ("evaluating do-while command near line %d, column %d",
+	     line (), column ());
+}
+
+void
+tree_do_while_command::accept (tree_walker& tw)
+{
+  tw.visit_do_while_command (*this);
+}
+
+// Do-Until
+
+void
+tree_do_until_command::eval (void)
+{
+  if (error_state)
+    return;
+
+  if (! expr)
+    panic_impossible ();
+
+  for (;;)
+    {
+      if (list)
+	{
+	  list->eval ();
+
+	  if (error_state)
+	    {
+	      eval_error ();
+	      return;
+	    }
+	}
+
+      if (quit_loop_now () || expr->is_logically_true ("do-until"))
+	break;
+    }
+}
+
+void
+tree_do_until_command::eval_error (void)
+{
+  if (error_state > 0)
+    ::error ("evaluating do-until command near line %d, column %d",
+	     line (), column ());
+}
+
+void
+tree_do_until_command::accept (tree_walker& tw)
+{
+  tw.visit_do_until_command (*this);
+}
+
 // For.
 
 tree_simple_for_command::~tree_simple_for_command (void)