YT-21233: Introduce TErrorAttributes as an opaque type for attributes to hide dependencies on IAttributeDictionary's API

Plan:

1) Remove `IAttributedDictionary` type from the public API. \+

2) Remove `Set` method from public API in favor of `operator<<=`. \+

3) Adopt `ConvertTo<T>` (or other name) CPO with proper extension into `NYT::NYson::ConvertTo` from `yt/core`.

4) Use CPO from (3) to eliminate direct dependency on `yt/core` of `Get/Find` methods from attributes API.

5) Adopt `ConvertToYsonString` (or other name) CPO with proper extension into `yt/core` customisations.

6) Use CPO from (5) to eliminate direct dependency on `yt/core` of `TErrorAttribute` ctor.

7) Swap attributes implementation to the one which doesn’t use `IAttributeDictionary`.

8) At this point `stripped_error*` can be moved to library/cpp/yt and so can recursively dependant on THROW macro methods `Get/Find/…`.

9) Adjust CPO’s to work with `std::string` instead of `TYsonString` assuming text format to be used (maybe `TString` for now).

10) Remove dep of `library/cpp/yt/error` on `yson` entirely.

This pull request covers steps 1 and 2 laying foundation to 3-4 being implemented in the next one
commit_hash:e899bccdef4ebed321ea2eb93215282694c261ac

1 files changed, 105 insertions, 0 deletions

diff --git a/library/cpp/yt/error/error_attributes.h b/library/cpp/yt/error/error_attributes.h
new file mode 100644
index 0000000000..88771f8360
--- /dev/null
+++ b/library/cpp/yt/error/error_attributes.h
@@ -0,0 +1,105 @@
+#pragma once
+
+#include "mergeable_dictionary.h"
+
+#include <library/cpp/yt/misc/optional.h>
+
+namespace NYT {
+
+////////////////////////////////////////////////////////////////////////////////
+
+// For now this is just an opaque handle to error attributes
+// used to remove dependency on IAttributeDictionary in public API.
+// Eventually it would be a simple hash map.
+// NB(arkady-e1ppa): For now most methods are defined in yt/yt/core/misc/stripped_error.cpp
+// eventually they will be moved here.
+class TErrorAttributes
+{
+public:
+    using TKey = TString;
+    using TValue = NYson::TYsonString;
+    using TKeyValuePair = std::pair<TKey, TValue>;
+
+    //! Returns the list of all keys in the dictionary.
+    std::vector<TString> ListKeys() const;
+
+    //! Returns the list of all key-value pairs in the dictionary.
+    std::vector<TKeyValuePair> ListPairs() const;
+
+    //! Returns the value of the attribute (null indicates that the attribute is not found).
+    NYson::TYsonString FindYson(TStringBuf key) const;
+
+    //! Sets the value of the attribute.
+    void SetYson(const TString& key, const NYson::TYsonString& value);
+
+    //! Removes the attribute.
+    //! Returns |true| if the attribute was removed or |false| if there is no attribute with this key.
+    bool Remove(const TString& key);
+
+    //! Removes all attributes.
+    void Clear();
+
+    //! Returns the value of the attribute (throws an exception if the attribute is not found).
+    NYson::TYsonString GetYson(TStringBuf key) const;
+
+    //! Same as #GetYson but removes the value.
+    NYson::TYsonString GetYsonAndRemove(const TString& key);
+
+    //! Returns |true| iff the given key is present.
+    bool Contains(TStringBuf key) const;
+
+    // TODO(arkady-e1ppa): By default deserialization is located at yt/core
+    // consider using deserialization of some default types (guid, string, int, double)
+    // to be supported and everything else not supported without inclusion of yt/core.
+    //! Finds the attribute and deserializes its value.
+    //! Throws if no such value is found.
+    template <class T>
+    T Get(TStringBuf key) const;
+
+    //! Same as #Get but removes the value.
+    template <class T>
+    T GetAndRemove(const TString& key);
+
+    //! Finds the attribute and deserializes its value.
+    //! Uses default value if no such attribute is found.
+    template <class T>
+    T Get(TStringBuf key, const T& defaultValue) const;
+
+    //! Same as #Get but removes the value if it exists.
+    template <class T>
+    T GetAndRemove(const TString& key, const T& defaultValue);
+
+    //! Finds the attribute and deserializes its value.
+    //! Returns null if no such attribute is found.
+    template <class T>
+    typename TOptionalTraits<T>::TOptional Find(TStringBuf key) const;
+
+    //! Same as #Find but removes the value if it exists.
+    template <class T>
+    typename TOptionalTraits<T>::TOptional FindAndRemove(const TString& key);
+
+    template <CMergeableDictionary TDictionary>
+    void MergeFrom(const TDictionary& dict);
+
+private:
+    void* Attributes_; // IAttributesDictionary*
+
+    friend class TErrorOr<void>;
+    explicit TErrorAttributes(void* attributes);
+
+    TErrorAttributes(const TErrorAttributes& other) = default;
+    TErrorAttributes& operator= (const TErrorAttributes& other) = default;
+
+    TErrorAttributes(TErrorAttributes&& other) = default;
+    TErrorAttributes& operator= (TErrorAttributes&& other) = default;
+};
+
+bool operator == (const TErrorAttributes& lhs, const TErrorAttributes& rhs);
+
+////////////////////////////////////////////////////////////////////////////////
+
+} // namespace NYT
+
+#define ERROR_ATTRIBUTES_INL_H_
+#include "error_attributes-inl.h"
+#undef ERROR_ATTRIBUTES_INL_H_