intermediate changes

ref:cde9a383711a11544ce7e107a78147fb96cc4029

1 files changed, 61 insertions, 0 deletions

diff --git a/util/stream/null.h b/util/stream/null.h
new file mode 100644
index 00000000000..8c335a9a789
--- /dev/null
+++ b/util/stream/null.h
@@ -0,0 +1,61 @@
+#pragma once
+
+#include "zerocopy.h"
+#include "output.h"
+
+/**
+ * @addtogroup Streams
+ * @{
+ */
+
+/**
+ * Null input stream. Does nothing, contains no data.
+ */
+class TNullInput: public IZeroCopyInput {
+public:
+    TNullInput() noexcept;
+    ~TNullInput() override;
+
+private:
+    size_t DoRead(void* buf, size_t len) override;
+    size_t DoSkip(size_t len) override;
+    size_t DoNext(const void** ptr, size_t len) override;
+};
+
+/**
+ * Null output stream. Just ignores whatever is written into it.
+ */
+class TNullOutput: public IOutputStream {
+public:
+    TNullOutput() noexcept;
+    ~TNullOutput() override;
+
+    TNullOutput(TNullOutput&&) noexcept = default;
+    TNullOutput& operator=(TNullOutput&&) noexcept = default;
+
+private:
+    void DoWrite(const void* buf, size_t len) override;
+};
+
+/**
+ * Null input-output stream.
+ *
+ * @see TNullInput
+ * @see TNullOutput
+ */
+class TNullIO: public TNullInput, public TNullOutput {
+public:
+    TNullIO() noexcept;
+    ~TNullIO() override;
+};
+
+namespace NPrivate {
+    TNullIO& StdNullStream() noexcept;
+}
+
+/**
+ * Standard null stream.
+ */
+#define Cnull (::NPrivate::StdNullStream())
+
+/** @} */