Intermediate changes

4 files changed, 228 insertions, 0 deletions

diff --git a/library/cpp/yt/misc/non_null_ptr-inl.h b/library/cpp/yt/misc/non_null_ptr-inl.h
new file mode 100644
index 0000000000..a14b1e9302
--- /dev/null
+++ b/library/cpp/yt/misc/non_null_ptr-inl.h
@@ -0,0 +1,49 @@
+#pragma once
+#ifndef NON_NULL_PTR_H_
+#error "Direct inclusion of this file is not allowed, include helpers.h"
+// For the sake of sane code completion.
+#include "non_null_ptr.h"
+#endif
+
+#include <library/cpp/yt/assert/assert.h>
+
+namespace NYT {
+
+////////////////////////////////////////////////////////////////////////////////
+
+template <class T>
+TNonNullPtrBase<T>::TNonNullPtrBase(T* ptr) noexcept
+    : Ptr_(ptr)
+{
+    YT_VERIFY(ptr);
+}
+
+template <class T>
+T* TNonNullPtrBase<T>::operator->() const noexcept
+{
+    return Ptr_;
+}
+
+template <class T>
+T& TNonNullPtrBase<T>::operator*() const noexcept
+{
+    return *Ptr_;
+}
+
+template <class T>
+TNonNullPtrBase<T>::TNonNullPtrBase() noexcept
+    : Ptr_(nullptr)
+{ }
+
+template <class T>
+TNonNullPtr<T> GetPtr(T& ref) noexcept
+{
+    TNonNullPtr<T> ptr;
+    ptr.Ptr_ = &ref;
+
+    return ptr;
+}
+
+////////////////////////////////////////////////////////////////////////////////
+
+} // namespace NYT
diff --git a/library/cpp/yt/misc/non_null_ptr.h b/library/cpp/yt/misc/non_null_ptr.h
new file mode 100644
index 0000000000..0005e4edb6
--- /dev/null
+++ b/library/cpp/yt/misc/non_null_ptr.h
@@ -0,0 +1,76 @@
+#pragma once
+
+#include "concepts.h"
+
+namespace NYT {
+
+////////////////////////////////////////////////////////////////////////////////
+
+// We have one really strange rule in our codestyle - mutable arguments are passed by pointer.
+// But if you are not a fan of making your life indefinite,
+// you can use this helper, that will validate that pointer you pass is not null.
+template <class T>
+class TNonNullPtr;
+
+template <class T>
+class TNonNullPtrBase
+{
+public:
+    TNonNullPtrBase(T* ptr) noexcept;
+    TNonNullPtrBase(const TNonNullPtrBase& other) = default;
+
+    TNonNullPtrBase(std::nullptr_t) = delete;
+    TNonNullPtrBase operator=(const TNonNullPtrBase&) = delete;
+
+    T* operator->() const noexcept;
+    T& operator*() const noexcept;
+
+protected:
+    T* Ptr_;
+
+    TNonNullPtrBase() noexcept;
+};
+
+template <class T>
+TNonNullPtr<T> GetPtr(T& ref) noexcept;
+
+template <class T>
+class TNonNullPtr
+    : public TNonNullPtrBase<T>
+{
+    using TConstPtr = TNonNullPtr<const T>;
+    friend TConstPtr;
+
+    using TNonNullPtrBase<T>::TNonNullPtrBase;
+
+    friend TNonNullPtr<T> GetPtr<T>(T& ref) noexcept;
+};
+
+// NB(pogorelov): Method definitions placed in .h file (instead of -inl.h) because of clang16 bug.
+// TODO(pogorelov): Move method definitions to helpers-inl.h when new clang will be used.
+template <CConst T>
+class TNonNullPtr<T>
+    : public TNonNullPtrBase<T>
+{
+    using TMutPtr = TNonNullPtr<std::remove_const_t<T>>;
+
+    using TNonNullPtrBase<T>::TNonNullPtrBase;
+
+    friend TNonNullPtr<T> GetPtr<T>(T& ref) noexcept;
+
+public:
+    TNonNullPtr(TMutPtr mutPtr) noexcept
+        : TNonNullPtrBase<T>()
+    {
+        TNonNullPtrBase<T>::Ptr_ = mutPtr.Ptr_;
+    }
+};
+
+
+////////////////////////////////////////////////////////////////////////////////
+
+} // namespace NYT
+
+#define NON_NULL_PTR_H_
+#include "non_null_ptr-inl.h"
+#undef NON_NULL_PTR_H_
diff --git a/library/cpp/yt/misc/unittests/non_null_ptr_ut.cpp b/library/cpp/yt/misc/unittests/non_null_ptr_ut.cpp
new file mode 100644
index 0000000000..a6903edc40
--- /dev/null
+++ b/library/cpp/yt/misc/unittests/non_null_ptr_ut.cpp
@@ -0,0 +1,102 @@
+#include <library/cpp/testing/gtest/gtest.h>
+
+#include <library/cpp/yt/misc/non_null_ptr.h>
+
+namespace NYT {
+namespace {
+
+////////////////////////////////////////////////////////////////////////////////
+
+enum EFuncResult {
+    Base,
+    ConstBase,
+    Derived,
+    ConstDerived,
+};
+
+enum EBinaryFuncResult {
+    Ok,
+    NotOk,
+};
+
+struct TBase
+{ };
+
+struct TDerived
+    : public TBase
+{ };
+
+EFuncResult Foo(TNonNullPtr<TBase> /*base*/)
+{
+    return EFuncResult::Base;
+}
+
+EFuncResult Foo(TNonNullPtr<const TBase> /*base*/)
+{
+    return EFuncResult::ConstBase;
+}
+
+EFuncResult Foo(TNonNullPtr<TDerived> /*derived*/)
+{
+    return EFuncResult::Derived;
+}
+
+EFuncResult Foo(TNonNullPtr<const TDerived> /*derived*/)
+{
+    return EFuncResult::ConstDerived;
+}
+
+[[maybe_unused]] EBinaryFuncResult Foo(int* /*derived*/)
+{
+    return EBinaryFuncResult::NotOk;
+}
+
+EBinaryFuncResult Foo(TNonNullPtr<int> /*derived*/)
+{
+    return EBinaryFuncResult::Ok;
+}
+
+EBinaryFuncResult Bar(TNonNullPtr<const int> /*arg*/)
+{
+    return EBinaryFuncResult::Ok;
+}
+
+EBinaryFuncResult Baz(TNonNullPtr<int> /*arg*/)
+{
+    return EBinaryFuncResult::Ok;
+}
+
+TEST(TNonNullPtrTest, Simple)
+{
+    TDerived derived{};
+    const auto& constDerived = derived;
+    EXPECT_EQ(EFuncResult::Derived, Foo(GetPtr(derived)));
+    EXPECT_EQ(EFuncResult::ConstDerived, Foo(GetPtr(constDerived)));
+
+    TBase base{};
+    const auto& constBase = base;
+    EXPECT_EQ(EFuncResult::Base, Foo(GetPtr(base)));
+    EXPECT_EQ(EFuncResult::ConstBase, Foo(GetPtr(constBase)));
+
+    int i{};
+    EXPECT_EQ(EBinaryFuncResult::Ok, Foo(GetPtr(i)));
+}
+
+TEST(TNonNullPtrTest, CastToConst)
+{
+    int i{};
+
+    EXPECT_EQ(EBinaryFuncResult::Ok, Bar(GetPtr(i)));
+}
+
+TEST(TNonNullPtrTest, ConstructionFromRawPointer)
+{
+    int i{};
+
+    EXPECT_EQ(EBinaryFuncResult::Ok, Baz(&i));
+}
+
+////////////////////////////////////////////////////////////////////////////////
+
+} // namespace
+} // namespace NYT
diff --git a/library/cpp/yt/misc/unittests/ya.make b/library/cpp/yt/misc/unittests/ya.make
index 611edd7217..5a071c887c 100644
--- a/library/cpp/yt/misc/unittests/ya.make
+++ b/library/cpp/yt/misc/unittests/ya.make
@@ -5,6 +5,7 @@ INCLUDE(${ARCADIA_ROOT}/library/cpp/yt/ya_cpp.make.inc)
 SRCS(
     enum_ut.cpp
     guid_ut.cpp
+    non_null_ptr_ut.cpp
     preprocessor_ut.cpp
     strong_typedef_ut.cpp
 )