Issue 4380: Some optimizations during dispatching

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

diff --git a/lily/include/smobs.hh b/lily/include/smobs.hh
index eeb385e1a26d6ae390714f0bb574c584d81da42a..eb8bb482f002b127bdd3090bd604f2fdaa86ee8c 100644 (file)
--- a/lily/include/smobs.hh
+++ b/lily/include/smobs.hh
@@ -21,6 +21,7 @@
 #define SMOBS_HH
 
 #include "lily-guile.hh"
+#include "lily-proto.hh"
 #include "warn.hh"
 #include <string>
 
@@ -127,26 +128,40 @@
 
 */
 
+// Initialization class.  Create a variable or static data member of
+// this type at global scope (or creation will happen too late for
+// Scheme initialization), initialising with a function to be called.
+// Reference somewhere (like in the constructor of the containing
+// class) to make sure the variable is actually instantiated.
+
+class Scm_init {
+  static const Scm_init * list_;
+  void (*const fun_)(void);
+  Scm_init const * const next_;
+  Scm_init ();          // don't use default constructor, don't define
+  Scm_init (const Scm_init &);  // don't define copy constructor
+public:
+  Scm_init (void (*fun) (void)) : fun_ (fun), next_ (list_)
+  { list_ = this; }
+  static void init ();
+};
+
 template <class Super>
 class Smob_base
 {
   static scm_t_bits smob_tag_;
-  static scm_t_bits init_id (void);
+  static Scm_init scm_init_;
+  static void init (void);
   static string smob_name_;
   static Super *unchecked_unsmob (SCM s)
   {
     return reinterpret_cast<Super *> (SCM_SMOB_DATA (s));
   }
 protected:
-  // This is an initialization with side effect.  It is called once,
-  // the first time smob_tag is actually getting called.  This
-  // allocates and initializes the type before it is first used for
-  // anything.
-  static scm_t_bits smob_tag ()
-  {
-    static scm_t_bits tag = init_id ();
-    return tag;
-  }
+  // reference scm_init_ in smob_tag which is sure to be called.  The
+  // constructor, in contrast, may not be called at all in classes
+  // like Smob1.
+  static scm_t_bits smob_tag () { (void) scm_init_; return smob_tag_; }
   Smob_base () { }
   static SCM register_ptr (Super *p);
   static Super *unregister_ptr (SCM obj);
@@ -206,17 +221,6 @@ private:
   static const int smob_proc_signature_ = -1;
 
 public:
-  static void init (void)
-  {
-    // This is stupid, but without forcing initialization at the
-    // Scheme startup hook stage, stuff like ly:undead? will not be
-    // defined when the first Scheme files are loaded.
-    //
-    // So we provide an explicit initialization routine that can be
-    // used with ADD_SCM_INIT_FUNC
-    (void) smob_tag ();
-  }
-#define ADD_SMOB_INIT(type) ADD_SCM_INIT_FUNC (Smob_init_ ## type, Smob_base<type>::init)
   static bool is_smob (SCM s)
   {
     return SCM_SMOB_PREDICATE (smob_tag (), s);
@@ -231,6 +235,14 @@ public:
   }
 };
 
+// derived_unsmob includes a dynamic_cast:
+
+template <class T>
+inline T *derived_unsmob (SCM arg)
+{
+  return dynamic_cast<T *> (T::unsmob (arg));
+}
+
 // Simple smobs
 template <class Super>
 class Simple_smob : public Smob_base<Super> {
@@ -250,14 +262,25 @@ public:
 void protect_smob (SCM smob, SCM *prot_cons);
 void unprotect_smob (SCM smob, SCM *prot_cons);
 
+// The Smob_core class is not templated and contains material not
+// depending on the Super class.
+
+class Smob_core {
+protected:
+  SCM self_scm_;
+  Smob_core () : self_scm_ (SCM_UNDEFINED) { };
+public:
+  SCM self_scm () const { return self_scm_; }
+  Listener get_listener (SCM callback);
+};
+
 template <class Super>
-class Smob : public Smob_base<Super> {
+class Smob : public Smob_core, public Smob_base<Super> {
 private:
-  SCM self_scm_;
   SCM protection_cons_;
   Smob (const Smob<Super> &); // Do not define!  Not copyable!
 protected:
-  Smob () : self_scm_ (SCM_UNDEFINED), protection_cons_ (SCM_EOL) { };
+  Smob () : protection_cons_ (SCM_EOL) { };
 public:
   static size_t free_smob (SCM obj)
   {
@@ -283,7 +306,6 @@ public:
     unprotect_smob (s, &protection_cons_);
     return s;
   }
-  SCM self_scm () const { return self_scm_; }
 };
 
 extern bool parsed_objects_should_be_dead;