--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libcc1/callbacks.cc	Fri Oct 27 22:46:09 2017 +0900
@@ -0,0 +1,90 @@
+/* Callback management.
+   Copyright (C) 2014-2017 Free Software Foundation, Inc.
+
+This file is part of GCC.
+
+GCC is free software; you can redistribute it and/or modify it under
+the terms of the GNU General Public License as published by the Free
+Software Foundation; either version 3, or (at your option) any later
+version.
+
+GCC is distributed in the hope that it will be useful, but WITHOUT ANY
+WARRANTY; without even the implied warranty of MERCHANTABILITY or
+FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+for more details.
+
+You should have received a copy of the GNU General Public License
+along with GCC; see the file COPYING3.  If not see
+<http://www.gnu.org/licenses/>.  */
+
+#include <cc1plugin-config.h>
+#include <string.h>
+#include <stdlib.h>
+#include "callbacks.hh"
+#include "libiberty.h"
+
+// An entry in the hash table.
+struct method
+{
+  const char *name;
+  cc1_plugin::callback_ftype *func;
+};
+
+// Hash function for struct method.
+static hashval_t
+hash_method (const void *a)
+{
+  const struct method *m = (const struct method *) a;
+
+  return htab_hash_string (m->name);
+}
+
+// Equality function for struct method.
+static int
+eq_method (const void *a, const void *b)
+{
+  const struct method *ma = (const struct method *) a;
+  const struct method *mb = (const struct method *) b;
+
+  return strcmp (ma->name, mb->name) == 0;
+}
+
+cc1_plugin::callbacks::callbacks ()
+  : m_registry (htab_create_alloc (10, hash_method, eq_method,
+				   free, xcalloc, free))
+{
+}
+
+cc1_plugin::callbacks::~callbacks ()
+{
+  htab_delete (m_registry);
+}
+
+void
+cc1_plugin::callbacks::add_callback (const char *name,
+				     cc1_plugin::callback_ftype *func)
+{
+  method m;
+  method **slot;
+
+  m.name = name;
+  m.func = func;
+
+  slot = (method **) htab_find_slot (m_registry, &m, INSERT);
+  *slot = XNEW (method);
+  **slot = m;
+}
+
+cc1_plugin::callback_ftype *
+cc1_plugin::callbacks::find_callback (const char *name)
+{
+  method m, *found;
+
+  m.name = name;
+
+  found = (method *) htab_find (m_registry, &m);
+  if (found == NULL)
+    return NULL;
+
+  return found->func;
+}