intermediate changes

ref:cde9a383711a11544ce7e107a78147fb96cc4029

1 files changed, 65 insertions, 0 deletions

diff --git a/library/cpp/yson_pull/output.h b/library/cpp/yson_pull/output.h
new file mode 100644
index 0000000000..2d78107a93
--- /dev/null
+++ b/library/cpp/yson_pull/output.h
@@ -0,0 +1,65 @@
+#pragma once
+
+#include "buffer.h"
+
+#include <util/generic/ptr.h>
+#include <util/generic/strbuf.h>
+#include <util/system/types.h>
+#include <util/system/yassert.h>
+
+#include <cstddef>
+#include <cstdio>
+#include <cstring>
+#include <memory>
+
+//! \brief Output stream adaptor interface.
+//!
+//! Represents a model of an optionally-buffered writer.
+namespace NYsonPull {
+    namespace NOutput {
+        class IStream {
+            output_buffer buffer_;
+
+        public:
+            virtual ~IStream() = default;
+
+            output_buffer& buffer() noexcept {
+                return buffer_;
+            }
+            const output_buffer& buffer() const noexcept {
+                return buffer_;
+            }
+
+            void flush_buffer(TStringBuf extra = {}) {
+                if (!extra.empty() || !buffer_.is_empty()) {
+                    do_flush_buffer(extra);
+                }
+                while (!buffer_.is_empty()) {
+                    do_flush_buffer({});
+                }
+            }
+
+        protected:
+            //! \brief Flush data to underlying stream.
+            //!
+            //! The implementation is to flush the buffer contents AND
+            //! extra argument to underlying stream.
+            //!
+            //! This way, at zero buffer size this interface implements an unbuffered
+            //! stream (with an added cost of a virtual call per each write).
+            //!
+            //! Write is assumed to always succeed unless it throws an exception.
+            virtual void do_flush_buffer(TStringBuf extra) = 0;
+        };
+
+        //! \brief Write data to C FILE* object.
+        THolder<IStream> FromStdioFile(FILE* file, size_t buffer_size = 0);
+
+        //! \brief Write data to POSIX file descriptor
+        THolder<IStream> FromPosixFd(int fd, size_t buffer_size = 65536);
+
+        THolder<IStream> FromOutputStream(IOutputStream* output, size_t buffer_size = 65536);
+
+        THolder<IStream> FromString(TString* output, size_t buffer_size = 1024);
+    }
+}