Rewrite Bind as two different classes

[libs/gl.git] / source / bindable.h

diff --git a/source/bindable.h b/source/bindable.h
index cd012fbbcef3d50b984a6dafbace86f49ce7f433..f534d7afd8e9788e412dd0d2ddd876eee0091c8e 100644 (file)
--- a/source/bindable.h
+++ b/source/bindable.h
@@ -1,16 +1,13 @@
-/* $Id$
-
-This file is part of libmspgl
-Copyright © 2010  Mikko Rasa, Mikkosoft Productions
-Distributed under the LGPL
-*/
-
 #ifndef MSP_GL_BINDABLE_H_
 #define MSP_GL_BINDABLE_H_
 
 namespace Msp {
 namespace GL {
 
+/**
+A helper class for single-point binding.  Provides tracking of the currently
+bound object.
+*/
 template<typename T>
 class Bindable
 {
@@ -24,18 +21,48 @@ protected:
                if(obj==cur_obj)
                        return false;
 
-               cur_obj=obj;
+               cur_obj = obj;
                return true;
        }
 
 public:
-       const T *current() const { return cur_obj; }
+       static const T *current() { return cur_obj; }
 };
 
 template<typename T>
 const T *Bindable<T>::cur_obj;
 
 
+/**
+A helper class for Bindables that revert to a default object on unbind.
+*/
+template<typename T>
+class BindableWithDefault: protected Bindable<T>
+{
+protected:
+       BindableWithDefault() { }
+
+public:
+       static const T *current()
+       {
+               if(!Bindable<T>::cur_obj)
+                       Bindable<T>::cur_obj = &default_object();
+               return Bindable<T>::cur_obj;
+       }
+
+       static void unbind()
+       {
+               default_object().bind();
+       }
+
+       static const T &default_object()
+       {
+               static T obj;
+               return obj;
+       }
+};
+
+
 /**
 RAII class for binding things.  Binds the thing upon construction and unbinds
 it upon destruction.  If a null pointer is given, unbinds upon construction and
@@ -44,35 +71,88 @@ does nothing upon destruction.
 class Bind
 {
 private:
-       struct Base
-       {
-               virtual ~Base() { }
-       };
+       typedef void CleanupFunc();
+
+       CleanupFunc *cleanup;
+
+public:
+       template<typename T>
+       Bind(T *o) { init(o); }
 
        template<typename T>
-       struct Binder: Base
+       Bind(const T *o) { init(o); }
+
+       template<typename T>
+       Bind(const T &o) { init(&o); }
+
+private:
+       template<typename T>
+       void init(const T *o)
        {
-               const T &obj;
+               cleanup = (o ? &unbind<T> : 0);
+               if(o)
+                       o->bind();
+               else
+                       T::unbind();
+       }
+
+public:
+       ~Bind()
+       { if(cleanup) cleanup(); }
 
-               Binder(const T &o): obj(o) { obj.bind(); }
-               ~Binder() { obj.unbind(); }
-       };
+private:
+       template<typename T>
+       static void unbind()
+       { T::unbind(); }
+};
 
-       Base *binder;
+
+/**
+Similar to Bind, but restores previous binding upon destruction.
+*/
+class BindRestore
+{
+private:
+       typedef void CleanupFunc(const void *);
+
+       const void *old;
+       CleanupFunc *cleanup;
 
 public:
        template<typename T>
-       Bind(const T &o): binder(new Binder<T>(o)) { }
+       BindRestore(T *o) { init(o); }
 
        template<typename T>
-       Bind(const T *o): binder(o ? new Binder<T>(*o) : 0) { if(!o) T::unbind(); }
+       BindRestore(const T *o) { init(o); }
+
+       template<typename T>
+       BindRestore(const T &o) { init(&o); }
 
 private:
-       Bind(const Bind &);
-       Bind &operator=(const Bind &);
+       template<typename T>
+       void init(T *o)
+       {
+               old = T::current();
+               cleanup = (o!=old ? &restore<T> : 0);
+               if(o)
+                       o->bind();
+               else if(old)
+                       T::unbind();
+       }
 
 public:
-       ~Bind() { delete binder; }
+       ~BindRestore()
+       { if(cleanup) cleanup(old); }
+
+private:
+       template<typename T>
+       static void restore(const void *o)
+       {
+               if(o)
+                       reinterpret_cast<const T *>(o)->bind();
+               else
+                       T::unbind();
+       }
 };
 
 } // namespace GL