Issue 4360: Reorganize smob initialization to make it more reliable

[lilypond.git] / lily / include / smobs.tcc

diff --git a/lily/include/smobs.tcc b/lily/include/smobs.tcc
index f7b6fe3e4b0a9a55a1746670092863afa312dc45..097047e32b05ff2f30763602c57edbee63304b6c 100644 (file)
--- a/lily/include/smobs.tcc
+++ b/lily/include/smobs.tcc
@@ -1,7 +1,7 @@
 /* -*- C++ -*-
   This file is part of LilyPond, the GNU music typesetter.
 
-  Copyright (C) 2005--2014 Han-Wen Nienhuys <hanwen@xs4all.nl>
+  Copyright (C) 2005--2015 Han-Wen Nienhuys <hanwen@xs4all.nl>
 
   LilyPond is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -28,6 +28,26 @@
 #include "smobs.hh"
 #include <typeinfo>
 
+template <class Super>
+SCM
+Smob_base<Super>::mark_trampoline (SCM arg)
+{
+  Super *ptr = Super::unsmob (arg);
+  if (ptr)
+    return ptr->mark_smob ();
+  return SCM_UNDEFINED;
+}
+
+template <class Super>
+int
+Smob_base<Super>::print_trampoline (SCM arg, SCM port, scm_print_state *p)
+{
+  Super *ptr = Super::unsmob (arg);
+  if (ptr)
+    return ptr->print_smob (port, p);
+  return 0;
+}
+
 template <class Super>
 SCM
 Smob_base<Super>::register_ptr (Super *p)
@@ -42,9 +62,33 @@ Smob_base<Super>::register_ptr (Super *p)
   return s;
 }
 
+// Defaults, should not actually get called
+template <class Super>
+SCM
+Smob_base<Super>::mark_smob ()
+{
+  return SCM_UNSPECIFIED;
+}
+
+template <class Super>
+size_t
+Smob_base<Super>::free_smob (SCM)
+{
+  return 0;
+}
+
+template <class Super>
+SCM
+Smob_base<Super>::equal_p (SCM, SCM)
+{
+  return SCM_BOOL_F;
+}
+
+// Default, will often get called
+
 template <class Super>
 int
-Smob_base<Super>::print_smob (SCM, SCM p, scm_print_state *)
+Smob_base<Super>::print_smob (SCM p, scm_print_state *)
 {
   scm_puts ("#<", p);
   scm_puts (smob_name_.c_str (), p);
@@ -58,20 +102,15 @@ Smob_base<Super>::unregister_ptr (SCM obj)
 {
   Super *p = Super::unchecked_unsmob (obj);
   scm_gc_unregister_collectable_memory (p, sizeof (*p), smob_name_.c_str ());
+  SCM_SET_SMOB_DATA (obj, static_cast<Super *> (0));
   return p;
 }
 
-template <class Super>
-scm_t_bits Smob_base<Super>::smob_tag_ = 0;
-
-template <class Super>
-Scm_init Smob_base<Super>::scm_init_ = init;
-
 template <class Super>
 string Smob_base<Super>::smob_name_;
 
 template <class Super>
-void Smob_base<Super>::init ()
+scm_t_bits Smob_base<Super>::init_id ()
 {
   smob_name_ = typeid (Super).name ();
   // Primitive demangling, suitable for GCC, should be harmless
@@ -79,8 +118,7 @@ void Smob_base<Super>::init ()
   // unsuitable for Texinfo documentation.  If that proves to be an
   // issue, we need some smarter strategy.
   smob_name_ = smob_name_.substr (smob_name_.find_first_not_of ("0123456789"));
-  assert(!smob_tag_);
-  smob_tag_ = scm_make_smob_type (smob_name_.c_str (), 0);
+  scm_t_bits smob_tag = scm_make_smob_type (smob_name_.c_str (), 0);
   // The following have trivial private default definitions not
   // referring to any aspect of the Super class apart from its name.
   // They should be overridden (or rather masked) at Super level: that
@@ -88,14 +126,19 @@ void Smob_base<Super>::init ()
   // While that's not a consideration for type_p_name_, it's easier
   // doing it like the rest.
 
-  if (Super::free_smob != 0)
-    scm_set_smob_free (smob_tag_, Super::free_smob);
-  if (Super::mark_smob != 0)
-    scm_set_smob_mark (smob_tag_, Super::mark_smob);
-  if (Super::print_smob != 0)
-    scm_set_smob_print (smob_tag_, Super::print_smob);
-  if (Super::equal_p != 0)
-    scm_set_smob_equalp (smob_tag_, Super::equal_p);
+  if (&Super::free_smob != &Smob_base<Super>::free_smob)
+    scm_set_smob_free (smob_tag, Super::free_smob);
+  // Old GCC versions get their type lattice for pointers-to-members
+  // tangled up to a degree where we need to typecast _both_ covariant
+  // types in order to be able to compare them.  The other comparisons
+  // are for static member functions and thus are ordinary function
+  // pointers which work without those contortions.
+  if (static_cast<SCM (Super::*)()>(&Super::mark_smob) !=
+      static_cast<SCM (Super::*)()>(&Smob_base<Super>::mark_smob))
+    scm_set_smob_mark (smob_tag, Super::mark_trampoline);
+  scm_set_smob_print (smob_tag, Super::print_trampoline);
+  if (&Super::equal_p != &Smob_base<Super>::equal_p)
+    scm_set_smob_equalp (smob_tag, Super::equal_p);
   if (Super::type_p_name_ != 0)
     {
       SCM subr = scm_c_define_gsubr (Super::type_p_name_, 1, 0, 0,
@@ -106,7 +149,13 @@ void Smob_base<Super>::init ()
                                      fundoc);
       scm_c_export (Super::type_p_name_, NULL);
     }
-  ly_add_type_predicate ((void *) unsmob, smob_name_.c_str ());
+  ly_add_type_predicate ((void *) is_smob, smob_name_.c_str ());
+  if (Super::smob_proc_signature_ >= 0)
+    scm_set_smob_apply (smob_tag,
+                        (scm_t_subr)Super::smob_proc,
+                        Super::smob_proc_signature_ >> 8,
+                        (Super::smob_proc_signature_ >> 4)&0xf,
+                        Super::smob_proc_signature_ & 0xf);
+  return smob_tag;
 }
-
 #endif