YQL-19616 Convert YQL lexer grammar to regexes

- [x] Parse YQL grammar to extract lexer grammar into `TLexerGrammar`.
- [x] Translate `TLexerGrammar` into regexes.
- [x] Implement a lexer via regexes `TRegexLexer` to test generated regexes validity.
- [x] Test on `Default` syntax mode.
- [x] Test on `ANSI` syntax mode.

---
- Related to https://github.com/ydb-platform/ydb/issues/15129
- Requirement for https://github.com/ytsaurus/ytsaurus/pull/1112

---

Pull Request resolved: https://github.com/ytsaurus/ytsaurus/pull/1127
commit_hash:03ffffe81cdafe7f93a4d3fd9a3212fe67f1c72d

1 files changed, 3 insertions, 1 deletions

diff --git a/yql/essentials/sql/v1/complete/sql_complete.cpp b/yql/essentials/sql/v1/complete/sql_complete.cpp
index 53cb4ada420..753d0a2835c 100644
--- a/yql/essentials/sql/v1/complete/sql_complete.cpp
+++ b/yql/essentials/sql/v1/complete/sql_complete.cpp
@@ -125,7 +125,9 @@ namespace NSQLComplete {
         INameService::TPtr names = MakeStaticNameService(MakeDefaultNameSet());
 
         return MakeSqlCompletionEngine([lexers = std::move(lexers)](bool ansi) {
-            return NSQLTranslationV1::MakeLexer(lexers, ansi, /* antlr4 = */ true, /* pure = */ true);
+            return NSQLTranslationV1::MakeLexer(
+                lexers, ansi, /* antlr4 = */ true, 
+                NSQLTranslationV1::ELexerFlavor::Pure);
         }, std::move(names));
     }