YT-19324: move YT provider to ydb/library/yql

This commit is formed by the following script: https://paste.yandex-team.ru/6f92e4b8-efc5-4d34-948b-15ee2accd7e7/text.
This commit has zero effect on all projects that depend on YQL.

The summary of changes:
- `yql/providers/yt -> ydb/library/yql/providers/yt `- the whole implementation of YT provider is moved into YDB code base for further export as a part of YT YQL plugin shared library;
- `yql/providers/stat/{expr_nodes,uploader} -> ydb/library/yql/providers/stat/{expr_nodes,uploader}` - a small interface without implementation and the description of stat expr nodes;
- `yql/core/extract_predicate/ut -> ydb/library/yql/core/extract_predicate/ut`;
- `yql/core/{ut,ut_common} -> ydb/library/yql/core/{ut,ut_common}`;
- `yql/core` is gone;
- `yql/library/url_preprocessing -> ydb/library/yql/core/url_preprocessing`.

**NB**: all new targets inside `ydb/` are under `IF (NOT CMAKE_EXPORT)` clause which disables them from open-source cmake generation and ya make build. They will be enabled in the subsequent commits.

1 files changed, 121 insertions, 0 deletions

diff --git a/library/cpp/skiff/skiff_schema.h b/library/cpp/skiff/skiff_schema.h
new file mode 100644
index 0000000000..8952a84bac
--- /dev/null
+++ b/library/cpp/skiff/skiff_schema.h
@@ -0,0 +1,121 @@
+#pragma once
+
+#include "public.h"
+
+#include <util/generic/string.h>
+#include <util/string/cast.h>
+
+#include <vector>
+
+namespace NSkiff {
+
+////////////////////////////////////////////////////////////////////////////////
+
+template <EWireType WireType>
+class TComplexSchema;
+
+using TTupleSchema = TComplexSchema<EWireType::Tuple>;
+using TVariant8Schema = TComplexSchema<EWireType::Variant8>;
+using TVariant16Schema = TComplexSchema<EWireType::Variant16>;
+using TRepeatedVariant8Schema = TComplexSchema<EWireType::RepeatedVariant8>;
+using TRepeatedVariant16Schema = TComplexSchema<EWireType::RepeatedVariant16>;
+
+using TTupleSchemaPtr = std::shared_ptr<TTupleSchema>;
+using TVariant8SchemaPtr = std::shared_ptr<TVariant8Schema>;
+using TVariant16SchemaPtr = std::shared_ptr<TVariant16Schema>;
+using TRepeatedVariant8SchemaPtr = std::shared_ptr<TRepeatedVariant8Schema>;
+using TRepeatedVariant16SchemaPtr = std::shared_ptr<TRepeatedVariant16Schema>;
+
+
+
+////////////////////////////////////////////////////////////////////////////////
+
+class TSkiffSchema
+    : public std::enable_shared_from_this<TSkiffSchema>
+{
+public:
+    virtual ~TSkiffSchema() = default;
+
+    EWireType GetWireType() const;
+    std::shared_ptr<TSkiffSchema> SetName(TString name);
+    const TString& GetName() const;
+
+    virtual const TSkiffSchemaList& GetChildren() const;
+
+protected:
+    explicit TSkiffSchema(EWireType type);
+
+private:
+    const EWireType Type_;
+    TString Name_;
+};
+
+bool operator==(const TSkiffSchema& lhs, const TSkiffSchema& rhs);
+bool operator!=(const TSkiffSchema& lhs, const TSkiffSchema& rhs);
+
+////////////////////////////////////////////////////////////////////////////////
+
+class TSimpleTypeSchema
+    : public TSkiffSchema
+{
+public:
+    explicit TSimpleTypeSchema(EWireType type);
+};
+
+////////////////////////////////////////////////////////////////////////////////
+
+template <EWireType WireType>
+class TComplexSchema
+    : public TSkiffSchema
+{
+public:
+    explicit TComplexSchema(TSkiffSchemaList elements);
+
+    virtual const TSkiffSchemaList& GetChildren() const override;
+
+private:
+    const TSkiffSchemaList Elements_;
+};
+
+////////////////////////////////////////////////////////////////////////////////
+
+bool IsSimpleType(EWireType type);
+TString GetShortDebugString(const std::shared_ptr<const TSkiffSchema>& schema);
+void PrintShortDebugString(const std::shared_ptr<const TSkiffSchema>& schema, IOutputStream* out);
+
+std::shared_ptr<TSimpleTypeSchema> CreateSimpleTypeSchema(EWireType type);
+std::shared_ptr<TTupleSchema> CreateTupleSchema(TSkiffSchemaList children);
+std::shared_ptr<TVariant8Schema> CreateVariant8Schema(TSkiffSchemaList children);
+std::shared_ptr<TVariant16Schema> CreateVariant16Schema(TSkiffSchemaList children);
+std::shared_ptr<TRepeatedVariant8Schema> CreateRepeatedVariant8Schema(TSkiffSchemaList children);
+std::shared_ptr<TRepeatedVariant16Schema> CreateRepeatedVariant16Schema(TSkiffSchemaList children);
+
+////////////////////////////////////////////////////////////////////////////////
+
+struct TSkiffSchemaPtrHasher
+{
+    size_t operator()(const std::shared_ptr<TSkiffSchema>& schema) const;
+};
+
+struct TSkiffSchemaPtrEqual
+{
+    size_t operator()(
+        const std::shared_ptr<TSkiffSchema>& lhs,
+        const std::shared_ptr<TSkiffSchema>& rhs) const;
+};
+
+} // namespace NSkiff
+
+////////////////////////////////////////////////////////////////////////////////
+
+template <>
+struct THash<NSkiff::TSkiffSchema>
+{
+    size_t operator()(const NSkiff::TSkiffSchema& schema) const;
+};
+
+////////////////////////////////////////////////////////////////////////////////
+
+#define SKIFF_SCHEMA_H
+#include "skiff_schema-inl.h"
+#undef SKIFF_SCHEMA_H