1 files changed, 65 insertions, 0 deletions
diff --git a/gnu/libg++/iostream/indstream.h b/gnu/libg++/iostream/indstream.h
new file mode 100644
index 000000000000..109928b4d5af
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+++ b/gnu/libg++/iostream/indstream.h
@@ -0,0 +1,65 @@
+//    This is part of the iostream library, providing -*- C++ -*- input/output.
+//    Copyright (C) 1992 Per Bothner.
+//
+//    This library is free software; you can redistribute it and/or
+//    modify it under the terms of the GNU Library General Public
+//    License as published by the Free Software Foundation; either
+//    version 2 of the License, or (at your option) any later version.
+//
+//    This library is distributed in the hope that it will be useful,
+//    but WITHOUT ANY WARRANTY; without even the implied warranty of
+//    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+//    Library General Public License for more details.
+//
+//    You should have received a copy of the GNU Library General Public
+//    License along with this library; if not, write to the Free
+//    Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+
+#ifndef _INDSTREAM_H
+#define _INDSTREAM_H
+
+#ifdef __GNUG__
+#pragma interface
+#endif
+
+#include <iostream.h>
+
+// An indirectbuf is one that forwards all of its I/O requests
+// to another streambuf.
+// All get-related requests are sent to get_stream().
+// All put-related requests are sent to put_stream().
+
+// An indirectbuf can be used to implement Common Lisp
+// synonym-streams and two-way-streams.
+//
+// class synonymbuf : public indirectbuf {
+//    Symbol *sym;
+//    synonymbuf(Symbol *s) { sym = s; }
+//    virtual streambuf *lookup_stream(int mode) {
+//        return coerce_to_streambuf(lookup_value(sym)); }
+// };
+
+class indirectbuf : public streambuf {
+  protected:
+    streambuf *_get_stream;  // Optional cache for get_stream().
+    streambuf *_put_stream;  // Optional cache for put_stream().
+    int _delete_flags;
+  public:
+    streambuf *get_stream()
+	{ return _get_stream ? _get_stream : lookup_stream(ios::in); }
+    streambuf *put_stream()
+	{ return _put_stream ? _put_stream : lookup_stream(ios::out); }
+    virtual streambuf *lookup_stream(int/*mode*/) { return NULL; } // ERROR!
+    indirectbuf(streambuf *get=NULL, streambuf *put=NULL, int delete_mode=0);
+    virtual ~indirectbuf();
+    virtual int xsputn(const char* s, int n);
+    virtual int xsgetn(char* s, int n);
+    virtual int underflow();
+    virtual int overflow(int c = EOF);
+    virtual streampos seekoff(streamoff, _seek_dir, int mode=ios::in|ios::out);
+    virtual streampos seekpos(streampos pos, int mode = ios::in|ios::out);
+    virtual int sync();
+    virtual int pbackfail(int c);
+};
+
+#endif /* !_INDSTREAM_H */