input/MaybeBuffered: proxy InputStream implementation which auto-uses BufferedInputStream

src/input/MaybeBufferedInputStream.cxx

@@ -0,0 +1,38 @@
+/*
+ * Copyright 2003-2018 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include "config.h"
+#include "MaybeBufferedInputStream.hxx"
+#include "BufferedInputStream.hxx"
+
+MaybeBufferedInputStream::MaybeBufferedInputStream(InputStreamPtr _input) noexcept
+	:ProxyInputStream(std::move(_input)) {}
+
+void
+MaybeBufferedInputStream::Update() noexcept
+{
+	const bool was_ready = IsReady();
+
+	ProxyInputStream::Update();
+
+	if (!was_ready && IsReady() && BufferedInputStream::IsEligible(*input))
+		/* our input has just become ready - check if we
+		   should buffer it */
+		SetInput(std::make_unique<BufferedInputStream>(std::move(input)));
+}