Add Filtered class

[libs/core.git] / source / filtered.h

diff --git a/source/filtered.h b/source/filtered.h
new file mode 100644 (file)
index 0000000..0575175
--- /dev/null
+++ b/source/filtered.h
@@ -0,0 +1,66 @@
+/* $Id$
+
+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