+/* $Id$
+
+This file is part of libmspio
+Copyright © 2008 Mikko Rasa, Mikkosoft Productions
+Distributed under the LGPL
+*/
+
+#ifndef MSP_IO_FILTERED_H_
+#define MSP_IO_FILTERED_H_
+
+namespace Msp {
+namespace IO {
+
+template<typename B, typename F>
+class Filtered: public B
+{
+private:
+ struct Activator
+ {
+ Filtered &f;
+
+ Activator(Filtered &f_): f(f_) { f.active=true; }
+ ~Activator() { f.active=false; }
+ };
+
+ F filter;
+ bool active;
+
+public:
+ Filtered(): filter(*this), active(false) { }
+
+ template<typename A0>
+ Filtered(A0 a0): B(a0), filter(*this), active(false) { }
+
+ template<typename A0, typename A1>
+ Filtered(A0 a0, A1 a1): B(a0, a1), filter(*this), active(false) { }
+
+ F &get_filter() { return filter; }
+protected:
+ virtual unsigned do_write(const char *b, unsigned s)
+ {
+ if(!active)
+ {
+ Activator a(*this);
+ return filter.write(b, s);
+ }
+ else
+ return B::do_write(b, s);
+ }
+
+ virtual unsigned do_read(char *b, unsigned s)
+ {
+ if(!active)
+ {
+ Activator a(*this);
+ return filter.read(b, s);
+ }
+ else
+ return B::do_read(b, s);
+ }
+};
+
+} // namespace IO
+} // namespace Msp
+
+#endif