YQL-19747: Support USE statement

Introduce global analysis which will be extended with more ParseTree analysis later.

---

- Related to `YQL-19747`
- Related to https://github.com/vityaman/ydb/issues/40

---

Pull Request resolved: https://github.com/ytsaurus/ytsaurus/pull/1281
commit_hash:848fb3fdd6bc9612769c47d66198fca018ff465f

1 files changed, 96 insertions, 0 deletions

diff --git a/yql/essentials/sql/v1/complete/analysis/global/use.cpp b/yql/essentials/sql/v1/complete/analysis/global/use.cpp
new file mode 100644
index 00000000000..da7dc6a5751
--- /dev/null
+++ b/yql/essentials/sql/v1/complete/analysis/global/use.cpp
@@ -0,0 +1,96 @@
+#include "use.h"
+
+namespace NSQLComplete {
+
+    namespace {
+
+        class TVisitor: public SQLv1Antlr4BaseVisitor {
+        public:
+            TVisitor(antlr4::TokenStream* tokens, size_t cursorPosition)
+                : Tokens_(tokens)
+                , CursorPosition_(cursorPosition)
+            {
+            }
+
+            std::any visitSql_stmt_core(SQLv1::Sql_stmt_coreContext* ctx) override {
+                if (ctx->use_stmt() || IsEnclosing(ctx)) {
+                    return visitChildren(ctx);
+                }
+                return {};
+            }
+
+            std::any visitUse_stmt(SQLv1::Use_stmtContext* ctx) override {
+                SQLv1::Cluster_exprContext* expr = ctx->cluster_expr();
+                if (!expr) {
+                    return {};
+                }
+
+                std::string provider;
+                std::string cluster;
+
+                if (SQLv1::An_idContext* ctx = expr->an_id()) {
+                    provider = ctx->getText();
+                }
+
+                if (SQLv1::Pure_column_or_namedContext* ctx = expr->pure_column_or_named()) {
+                    cluster = ctx->getText();
+                }
+
+                if (cluster.empty()) {
+                    return {};
+                }
+
+                return TUseContext{
+                    .Provider = std::move(provider),
+                    .Cluster = std::move(cluster),
+                };
+            }
+
+            std::any aggregateResult(std::any aggregate, std::any nextResult) override {
+                if (nextResult.has_value()) {
+                    return nextResult;
+                }
+                return aggregate;
+            }
+
+            bool shouldVisitNextChild(antlr4::tree::ParseTree* node, const std::any& /*currentResult*/) override {
+                return TextInterval(node).a < static_cast<ssize_t>(CursorPosition_);
+            }
+
+        private:
+            bool IsEnclosing(antlr4::tree::ParseTree* tree) const {
+                return TextInterval(tree).properlyContains(CursorInterval());
+            }
+
+            antlr4::misc::Interval TextInterval(antlr4::tree::ParseTree* tree) const {
+                auto tokens = tree->getSourceInterval();
+                if (tokens.b == -1) {
+                    tokens.b = tokens.a;
+                }
+                return antlr4::misc::Interval(
+                    Tokens_->get(tokens.a)->getStartIndex(),
+                    Tokens_->get(tokens.b)->getStopIndex());
+            }
+
+            antlr4::misc::Interval CursorInterval() const {
+                return antlr4::misc::Interval(CursorPosition_, CursorPosition_);
+            }
+
+            antlr4::TokenStream* Tokens_;
+            size_t CursorPosition_;
+        };
+
+    } // namespace
+
+    TMaybe<TUseContext> FindUseStatement(
+        SQLv1::Sql_queryContext* ctx,
+        antlr4::TokenStream* tokens,
+        size_t cursorPosition) {
+        std::any result = TVisitor(tokens, cursorPosition).visit(ctx);
+        if (!result.has_value()) {
+            return Nothing();
+        }
+        return std::any_cast<TUseContext>(result);
+    }
+
+} // namespace NSQLComplete