YQL-20307: Support inline subqueries

- Alter grammar to support inline subqueries.
- Support inline subqueries in `sql/v1` (translator).
- Introduce `sql/v1/proto_ast/parse_tree.h` for reusable parse tree predicates.
- Support inline subqueries in `sql/v1/format`.
- Support inline subqueries in `sql/v1/complete`.
- Add some SQL-tests.
- Pass all tests.
commit_hash:075b2240778d071e1c7542f912d3cc83019ef849

4 files changed, 60 insertions, 5 deletions

diff --git a/yql/essentials/sql/v1/complete/analysis/global/column.cpp b/yql/essentials/sql/v1/complete/analysis/global/column.cpp
index 3f71ae6763d..d8c73e00b7f 100644
--- a/yql/essentials/sql/v1/complete/analysis/global/column.cpp
+++ b/yql/essentials/sql/v1/complete/analysis/global/column.cpp
@@ -295,6 +295,30 @@ namespace NSQLComplete {
             const TNamedNodes* Nodes_;
         };
 
+        class TEnclosingSelectVisitor: public TSQLv1NarrowingVisitor {
+        public:
+            explicit TEnclosingSelectVisitor(const TParsedInput& input)
+                : TSQLv1NarrowingVisitor(input)
+            {
+            }
+
+            std::any visitSelect_core(SQLv1::Select_coreContext* ctx) override {
+                if (!IsEnclosing(ctx)) {
+                    return {};
+                }
+
+                Enclosing_ = ctx;
+                return visitChildren(ctx);
+            }
+
+            SQLv1::Select_coreContext* GetEnclosing() && {
+                return Enclosing_;
+            }
+
+        private:
+            SQLv1::Select_coreContext* Enclosing_ = nullptr;
+        };
+
         class TVisitor: public TSQLv1NarrowingVisitor {
         public:
             TVisitor(const TParsedInput& input, const TNamedNodes* nodes)
@@ -343,11 +367,23 @@ namespace NSQLComplete {
             const TNamedNodes* Nodes_;
         };
 
+        antlr4::ParserRuleContext* Enclosing(const TParsedInput& input) {
+            TEnclosingSelectVisitor visitor(input);
+            visitor.visit(input.SqlQuery);
+
+            antlr4::ParserRuleContext* ctx = std::move(visitor).GetEnclosing();
+            if (!ctx) {
+                ctx = input.SqlQuery;
+            }
+
+            return ctx;
+        }
+
     } // namespace
 
     TMaybe<TColumnContext> InferColumnContext(TParsedInput input, const TNamedNodes& nodes) {
         // TODO: add utility `auto ToMaybe<T>(std::any any) -> TMaybe<T>`
-        std::any result = TVisitor(input, &nodes).visit(input.SqlQuery);
+        std::any result = TVisitor(input, &nodes).visit(Enclosing(input));
         if (!result.has_value()) {
             return Nothing();
         }
diff --git a/yql/essentials/sql/v1/complete/analysis/global/named_node.cpp b/yql/essentials/sql/v1/complete/analysis/global/named_node.cpp
index af8c17d3da2..4199da625c2 100644
--- a/yql/essentials/sql/v1/complete/analysis/global/named_node.cpp
+++ b/yql/essentials/sql/v1/complete/analysis/global/named_node.cpp
@@ -99,8 +99,6 @@ namespace NSQLComplete {
 
                 if (auto* expr = ctx->expr()) {
                     (*Names_)[std::move(*id)] = expr;
-                } else if (auto* subselect = ctx->subselect_stmt()) {
-                    (*Names_)[std::move(*id)] = subselect;
                 } else {
                     (*Names_)[std::move(*id)] = std::monostate();
                 }
diff --git a/yql/essentials/sql/v1/complete/analysis/global/named_node.h b/yql/essentials/sql/v1/complete/analysis/global/named_node.h
index 07e1e6f91b9..0050915f523 100644
--- a/yql/essentials/sql/v1/complete/analysis/global/named_node.h
+++ b/yql/essentials/sql/v1/complete/analysis/global/named_node.h
@@ -13,7 +13,6 @@ namespace NSQLComplete {
 
     using TNamedNode = std::variant<
         SQLv1::ExprContext*,
-        SQLv1::Subselect_stmtContext*,
         NYT::TNode,
         std::monostate>;
 
diff --git a/yql/essentials/sql/v1/complete/sql_complete_ut.cpp b/yql/essentials/sql/v1/complete/sql_complete_ut.cpp
index ecb3084dcba..679230c7a24 100644
--- a/yql/essentials/sql/v1/complete/sql_complete_ut.cpp
+++ b/yql/essentials/sql/v1/complete/sql_complete_ut.cpp
@@ -1,6 +1,6 @@
 #include "sql_complete.h"
-
 #include <yql/essentials/sql/v1/complete/syntax/grammar.h>
+
 #include <yql/essentials/sql/v1/complete/name/cache/local/cache.h>
 #include <yql/essentials/sql/v1/complete/name/cluster/static/discovery.h>
 #include <yql/essentials/sql/v1/complete/name/object/simple/schema.h>
@@ -857,6 +857,8 @@ Y_UNIT_TEST_SUITE(SqlCompleteTests) {
 
         UNIT_ASSERT_VALUES_EQUAL(Complete(engine, "$x = sel#"), expected);
         UNIT_ASSERT_VALUES_EQUAL(Complete(engine, "$x = (sel#)"), expected);
+        UNIT_ASSERT_VALUES_EQUAL(Complete(engine, "SELECT (sel#)"), expected);
+        UNIT_ASSERT_VALUES_EQUAL(Complete(engine, "SELECT * FROM t WHERE (sel#)"), expected);
     }
 
     Y_UNIT_TEST(Upsert) {
@@ -1813,6 +1815,26 @@ Y_UNIT_TEST_SUITE(SqlCompleteTests) {
         UNIT_ASSERT_VALUES_EQUAL(CompleteTop(expected.size(), engine, query), expected);
     }
 
+    Y_UNIT_TEST(ColumnAtSubqueryExpresson) {
+        auto engine = MakeSqlCompletionEngineUT();
+
+        TVector<TString> input = {
+            R"sql(SELECT (SELECT # FROM (SELECT 1 AS a));)sql",
+            R"sql(SELECT 1 + (SELECT # FROM (SELECT 1 AS a));)sql",
+            R"sql(SELECT * FROM t WHERE (SELECT # FROM (SELECT 1 AS a));)sql",
+            R"sql(SELECT * FROM t WHERE 1 < (SELECT # FROM (SELECT 1 AS a));)sql",
+        };
+
+        TVector<TCandidate> expected = {
+            {ColumnName, "a"},
+        };
+
+        UNIT_ASSERT_VALUES_EQUAL(CompleteTop(expected.size(), engine, input[0]), expected);
+        UNIT_ASSERT_VALUES_EQUAL(CompleteTop(expected.size(), engine, input[1]), expected);
+        UNIT_ASSERT_VALUES_EQUAL(CompleteTop(expected.size(), engine, input[2]), expected);
+        UNIT_ASSERT_VALUES_EQUAL(CompleteTop(expected.size(), engine, input[3]), expected);
+    }
+
     Y_UNIT_TEST(NoBindingAtQuoted) {
         auto engine = MakeSqlCompletionEngineUT();