feat: add Snowflake SQL parser to monorepo (#24)

Add ANTLR4-based Snowflake SQL parser from snowsql-parser repository into the parser monorepo.

Changes:
- Add snowflake/ directory with grammar files (SnowflakeLexer.g4, SnowflakeParser.g4)
- Add Makefile with build and test targets following the pattern of other parsers
- Include 25 SQL test examples covering various Snowflake syntax features
- Update package name and import paths to github.com/bytebase/parser/snowflake
- Add snowflake to CI workflow to run tests automatically
- All 25 test cases passing

🤖 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"
+          ALL_PARSERS="redshift postgresql cql snowflake"
           # Add more parsers here as they are added to the repository
           # ALL_PARSERS="redshift mysql postgresql"
 

snowflake/Makefile

@@ -0,0 +1,7 @@
+all: build test
+
+build:
+	python3 build_id_contains_non_reserved_keywords.py && antlr -Dlanguage=Go -package snowflake -visitor -o . SnowflakeLexer.g4 SnowflakeParser.g4
+
+test:
+	go test -v -run TestSnowflakeSQLParser

snowflake/README.md

@@ -0,0 +1,37 @@
+The plsql-parser is a parser for Snowflake. 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/snowflake).
+
+## 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-plsql
+
+1. Clone the `SnowflakeLexer.g4` and `SnowflakeParser.g4` grammar files from https://github.com/antlr/grammars-v4/tree/master/sql/snowflake.
+1. run `./build.sh` to generate the parser code.
+
+## Test the parser
+
+Run `TestSnowflakeSQLParser` 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