feat: add T-SQL parser to monorepo (#25)

Add ANTLR4-based T-SQL (Transact-SQL) parser from tsql-parser repository into the parser monorepo.

Changes:
- Add tsql/ directory with grammar files (TSqlLexer.g4, TSqlParser.g4)
- Add Makefile with build and test targets following the pattern of other parsers
- Include 143 SQL test examples covering comprehensive T-SQL features
- Update package name and import paths to github.com/bytebase/parser/tsql
- Add tsql to CI workflow to run tests automatically
- Include helper files (keyword_map.go, tsql_base_lexer.go) for lexer functionality
- All test cases passing

Test coverage includes:
- DDL statements (CREATE, ALTER, DROP for databases, tables, views, indexes, etc.)
- DML statements (SELECT, INSERT, UPDATE, DELETE, MERGE)
- Stored procedures and functions
- Control flow statements
- Built-in functions (date, string, math, cryptographic, JSON, etc.)
- T-SQL specific features (DBCC, hints, transactions, triggers, etc.)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-authored-by: Claude <[email protected]>

Author: h3n4l

.github/workflows/tests.yml

@@ -34,7 +34,7 @@ jobs:
         id: set-matrix
         run: |
           # List of all available parsers
-          ALL_PARSERS="redshift postgresql cql snowflake"
+          ALL_PARSERS="redshift postgresql cql snowflake tsql"
           # Add more parsers here as they are added to the repository
           # ALL_PARSERS="redshift mysql postgresql"
 

tsql/Makefile

@@ -0,0 +1,7 @@
+all: build test
+
+build:
+	antlr -Dlanguage=Go -package tsql -visitor -o . TSqlLexer.g4 TSqlParser.g4
+
+test:
+	go test -v -run TestTSQLParser

tsql/README.md

@@ -0,0 +1,43 @@
+The tsql-parser is a parser for T-SQL. It is based on the [ANTLR4](https://github.com/antlr/antlr4) and use the grammar from [antlr4-grammars-plsql](https://github.com/antlr/grammars-v4/tree/master/sql/tsql).
+
+## Build
+
+Before build, you need to install the ANTLR4.
+
+requirements:
+
+- https://github.com/antlr/antlr4/blob/master/doc/getting-started.md
+- https://github.com/antlr/antlr4/blob/master/doc/go-target.md
+
+```bash
+./build.sh
+```
+
+## Update grammar
+
+### Manually change the grammar file in this project
+
+1. run `./build.sh` to generate the parser code.
+
+### From antlr4-grammars-tsql
+
+1. Clone the `TSqlLexer.g4` and `TSqlParser.g4` grammar files from https://github.com/antlr/grammars-v4/tree/master/sql/snowflake.
+2. Clone the examples[https://github.com/antlr/grammars-v4/tree/master/sql/tsql/examples], and use it for test.
+3. run `./build.sh` to generate the parser code.
+
+## Test the parser
+
+Run `TestTSQLParser` in `parser_test.go` to test the parser.
+
+```bash
+go test -v
+```
+
+## References
+
+- ANTLR4 Getting Started https://github.com/antlr/antlr4/blob/master/doc/getting-started.md
+- ANTLR4 Go Garget https://github.com/antlr/antlr4/blob/master/doc/go-target.md
+
+## Port
+
+Port folder contains the ported code in another language.