Extract wxPipeInputStream and wxPipeOutputStream in a header.

No real changes, just put these classes in a private header. They're still not
part of the public API but at least it will be easier to reuse them inside the
library itself in the upcoming commits.

See #10258.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@74336 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/unix/private/pipestream.h

@@ -0,0 +1,38 @@
+///////////////////////////////////////////////////////////////////////////////
+// Name:        wx/unix/private/pipestream.h
+// Purpose:     Unix wxPipeInputStream and wxPipeOutputStream declarations
+// Author:      Vadim Zeitlin
+// Created:     2013-06-08 (extracted from wx/unix/pipe.h)
+// RCS-ID:      $Id$
+// Copyright:   (c) 2013 Vadim Zeitlin <vadim@wxwidgets.org>
+// Licence:     wxWindows licence
+///////////////////////////////////////////////////////////////////////////////
+
+#ifndef _WX_UNIX_PRIVATE_PIPESTREAM_H_
+#define _WX_UNIX_PRIVATE_PIPESTREAM_H_
+
+#include "wx/wfstream.h"
+
+class wxPipeInputStream : public wxFileInputStream
+{
+public:
+    wxEXPLICIT wxPipeInputStream(int fd) : wxFileInputStream(fd) { }
+
+    // return true if the pipe is still opened
+    bool IsOpened() const { return !Eof(); }
+
+    // return true if we have anything to read, don't block
+    virtual bool CanRead() const;
+};
+
+class wxPipeOutputStream : public wxFileOutputStream
+{
+public:
+    wxPipeOutputStream(int fd) : wxFileOutputStream(fd) { }
+
+    // Override the base class version to ignore "pipe full" errors: this is
+    // not an error for this class.
+    size_t OnSysWrite(const void *buffer, size_t size);
+};
+
+#endif // _WX_UNIX_PRIVATE_PIPESTREAM_H_