intermediate changes

ref:cde9a383711a11544ce7e107a78147fb96cc4029

1 files changed, 140 insertions, 0 deletions

diff --git a/library/cpp/yt/yson_string/string.h b/library/cpp/yt/yson_string/string.h
new file mode 100644
index 0000000000..e13af37a6d
--- /dev/null
+++ b/library/cpp/yt/yson_string/string.h
@@ -0,0 +1,140 @@
+#pragma once
+
+#include "public.h"
+
+#include <library/cpp/yt/memory/ref.h>
+
+#include <variant>
+
+namespace NYT::NYson {
+
+////////////////////////////////////////////////////////////////////////////////
+
+//! Contains a sequence of bytes in YSON encoding annotated with EYsonType describing
+//! the content. Could be null. Non-owning.
+class TYsonStringBuf
+{
+public:
+    //! Constructs a null instance.
+    TYsonStringBuf();
+
+    //! Constructs an instance from TYsonString.
+    TYsonStringBuf(const TYsonString& ysonString);
+
+    //! Constructs a non-null instance with given type and content.
+    explicit TYsonStringBuf(
+        const TString& data,
+        EYsonType type = EYsonType::Node);
+
+    //! Constructs a non-null instance with given type and content.
+    explicit TYsonStringBuf(
+        TStringBuf data,
+        EYsonType type = EYsonType::Node);
+
+    //! Constructs a non-null instance with given type and content
+    //! (without this overload there is no way to construct TYsonStringBuf from
+    //! string literal).
+    explicit TYsonStringBuf(
+        const char* data,
+        EYsonType type = EYsonType::Node);
+
+    //! Returns |true| if the instance is not null.
+    explicit operator bool() const;
+
+    //! Returns the underlying YSON bytes. The instance must be non-null.
+    TStringBuf AsStringBuf() const;
+
+    //! Returns type of YSON contained here. The instance must be non-null.
+    EYsonType GetType() const;
+
+protected:
+    TStringBuf Data_;
+    EYsonType Type_;
+    bool Null_;
+};
+
+////////////////////////////////////////////////////////////////////////////////
+
+//! An owning version of TYsonStringBuf.
+/*!
+ *  Internally captures the data either via TString or a polymorphic ref-counted holder.
+ */
+class TYsonString
+{
+public:
+    //! Constructs a null instance.
+    TYsonString();
+
+    //! Constructs an instance from TYsonStringBuf.
+    //! Copies the data into a ref-counted payload.
+    explicit TYsonString(const TYsonStringBuf& ysonStringBuf);
+
+    //! Constructs an instance from TStringBuf.
+    //! Copies the data into a ref-counted payload.
+    explicit TYsonString(
+        TStringBuf data,
+        EYsonType type = EYsonType::Node);
+
+    //! Constructs an instance from TString.
+    //! Zero-copy for CoW TString: retains the reference to TString in payload.
+    explicit TYsonString(
+        const TString& data,
+        EYsonType type = EYsonType::Node);
+
+    //! Constructs an instance from TSharedRef.
+    //! Zero-copy; retains the reference to TSharedRef holder in payload.
+    explicit TYsonString(
+        const TSharedRef& ref,
+        EYsonType type = EYsonType::Node);
+
+    //! Returns |true| if the instance is not null.
+    explicit operator bool() const;
+
+    //! Returns type of YSON contained here. The instance must be non-null.
+    EYsonType GetType() const;
+
+    //! Returns the non-owning data. The instance must be non-null.
+    TStringBuf AsStringBuf() const;
+
+    //! Returns the data represented by TString. The instance must be non-null.
+    //! Copies the data in case the payload is not TString.
+    TString ToString() const;
+
+    //! Computes the hash code.
+    size_t ComputeHash() const;
+
+private:
+    struct TNullPayload
+    { };
+
+    using THolder = TRefCountedPtr;
+
+    std::variant<TNullPayload, THolder, TString> Payload_;
+
+    const char* Begin_;
+    ui64 Size_ : 56;
+    EYsonType Type_ : 8;
+};
+
+////////////////////////////////////////////////////////////////////////////////
+
+bool operator == (const TYsonString& lhs, const TYsonString& rhs);
+bool operator == (const TYsonString& lhs, const TYsonStringBuf& rhs);
+bool operator == (const TYsonStringBuf& lhs, const TYsonString& rhs);
+bool operator == (const TYsonStringBuf& lhs, const TYsonStringBuf& rhs);
+
+bool operator != (const TYsonString& lhs, const TYsonString& rhs);
+bool operator != (const TYsonString& lhs, const TYsonStringBuf& rhs);
+bool operator != (const TYsonStringBuf& lhs, const TYsonString& rhs);
+bool operator != (const TYsonStringBuf& lhs, const TYsonStringBuf& rhs);
+
+TString ToString(const TYsonString& yson);
+TString ToString(const TYsonStringBuf& yson);
+
+////////////////////////////////////////////////////////////////////////////////
+
+} // namespace NYT::NYson
+
+#define STRING_INL_H_
+#include "string-inl.h"
+#undef STRING_INL_H_