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, 61 insertions, 0 deletions

diff --git a/library/cpp/skiff/skiff_schema-inl.h b/library/cpp/skiff/skiff_schema-inl.h
new file mode 100644
index 00000000000..d66325b222d
--- /dev/null
+++ b/library/cpp/skiff/skiff_schema-inl.h
@@ -0,0 +1,61 @@
+#pragma once
+
+#ifndef SKIFF_SCHEMA_H
+#error "Direct inclusion of this file is not allowed, include skiff_schema.h"
+// For the sake of sane code completion.
+#include "skiff_schema.h"
+#endif
+#undef SKIFF_SCHEMA_H
+
+namespace NSkiff {
+
+////////////////////////////////////////////////////////////////////////////////
+
+inline bool IsSimpleType(EWireType type)
+{
+    switch (type) {
+        case EWireType::Int8:
+        case EWireType::Int16:
+        case EWireType::Int32:
+        case EWireType::Int64:
+        case EWireType::Int128:
+
+        case EWireType::Uint8:
+        case EWireType::Uint16:
+        case EWireType::Uint32:
+        case EWireType::Uint64:
+        case EWireType::Uint128:
+
+        case EWireType::Double:
+        case EWireType::Boolean:
+        case EWireType::String32:
+        case EWireType::Yson32:
+        case EWireType::Nothing:
+            return true;
+        case EWireType::Tuple:
+        case EWireType::Variant8:
+        case EWireType::Variant16:
+        case EWireType::RepeatedVariant8:
+        case EWireType::RepeatedVariant16:
+            return false;
+    }
+    Y_FAIL();
+}
+
+////////////////////////////////////////////////////////////////////////////////
+
+template <EWireType WireType>
+TComplexSchema<WireType>::TComplexSchema(TSkiffSchemaList elements)
+    : TSkiffSchema(WireType)
+    , Elements_(std::move(elements))
+{ }
+
+template <EWireType WireType>
+const TSkiffSchemaList& TComplexSchema<WireType>::GetChildren() const
+{
+    return Elements_;
+}
+
+////////////////////////////////////////////////////////////////////////////////
+
+} // namespace NSkiff