feat: initial commit

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Co-Authored-By: Claude <[email protected]>

Author: h3n4l

CLAUDE.md

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+# Redshift Parser Development Guide
+
+## Project Overview
+
+This repository is a Redshift parser built with ANTLR 4, forked from github.com/bytebase/postgresql-parser. Due to incompatibility issues with PostgreSQL, this separate repository was created to support Amazon Redshift-specific syntax and features.
+
+## Architecture
+
+### Core Components
+
+1. **ANTLR Grammar Files**:
+   - `RedshiftLexer.g4` - Tokenization rules for Redshift SQL
+   - `RedshiftParser.g4` - Parser grammar with 200+ statement types
+   - Generated Go files: `redshift_parser.go`, `redshift_lexer.go`, etc.
+
+2. **Base Classes**:
+   - `redshift_parser_base.go` - Engine-aware parser with PostgreSQL/Redshift support
+   - `redshift_lexer_base.go` - Base lexer implementation
+   - `string_stack.go` - Utility for string stack operations
+
+3. **Supporting Files**:
+   - `keywords.go` - 600+ PostgreSQL keywords with reserved status
+   - `builtin_function.go` - Built-in function definitions
+   - `build.sh` - ANTLR code generation script
+
+### Engine Support
+
+The parser supports multiple database engines:
+- `EnginePostgreSQL` - Standard PostgreSQL syntax
+- `EngineRedshift` - Amazon Redshift-specific syntax extensions
+
+## Development Guidelines
+
+### Code Conventions
+
+1. **Follow existing patterns**: Always examine existing code before making changes
+2. **Token/Rule/Name Convention**: Maintain consistency with current ANTLR grammar naming
+3. **Engine-specific features**: Use engine detection for Redshift-specific syntax
+4. **Error handling**: Implement proper error listeners and recovery mechanisms
+
+### Testing Requirements
+
+**CRITICAL**: Every change must include a related test case.
+
+1. **Test Structure**:
+   - Add SQL test files to the `examples/` directory
+   - Use Go-based tests in `parser_test.go` and `engine_specific_test.go`
+   - Tests automatically parse all SQL files in `examples/`
+
+2. **Test Content Sources**:
+   - Reference https://docs.aws.amazon.com/redshift/latest/dg/c_SQL_commands.html
+   - Crawl syntax examples from AWS Redshift documentation
+   - Use real-world SQL examples when possible
+
+3. **Test Categories**:
+   - DDL: CREATE, ALTER, DROP statements
+   - DML: SELECT, INSERT, UPDATE, DELETE
+   - Redshift-specific: IDENTITY columns, DISTKEY, SORTKEY, etc.
+   - Advanced: Window functions, CTEs, JSON operations
+
+### Adding New Features
+
+1. **Grammar Changes**:
+   ```bash
+   # Edit RedshiftLexer.g4 or RedshiftParser.g4
+   # Run build script to regenerate Go code
+   ./build.sh
+   ```
+
+2. **Engine-Specific Logic**:
+   - Use `GetEngine()` method to detect Redshift vs PostgreSQL
+   - Implement conditional parsing for dialect-specific features
+   - See `engine_specific_test.go` for examples
+
+3. **Testing Process**:
+   - Create SQL test files in `examples/`
+   - Run tests: `go test -v`
+   - Verify both parsing success and error handling
+
+### Common Tasks
+
+#### Adding Redshift-Specific Syntax
+
+1. Identify the syntax difference from PostgreSQL
+2. Update the appropriate grammar file (lexer or parser)
+3. Add engine-specific logic if needed
+4. Create test cases with AWS documentation examples
+5. Verify tests pass for both engines
+
+#### Adding New Keywords
+
+1. Add to `keywords.go` with appropriate reserved status
+2. Update lexer grammar if needed
+3. Test keyword recognition in various contexts
+
+#### Adding Built-in Functions
+
+1. Add to `builtin_function.go` in appropriate category
+2. Update parser rules if function has special syntax
+3. Test function parsing and recognition
+
+## Build and Test Commands
+
+**IMPORTANT**: Always run `./build.sh` before running tests to generate the latest Go code from ANTLR grammars.
+
+```bash
+# Generate parser code from ANTLR grammars (REQUIRED before testing)
+./build.sh
+
+# Run all tests
+go test -v
+
+# Run specific test
+go test -run TestParser -v
+
+# Run benchmarks
+go test -bench=. -v
+```
+
+## References
+
+- [AWS Redshift SQL Commands](https://docs.aws.amazon.com/redshift/latest/dg/c_SQL_commands.html)
+- [ANTLR 4 Documentation](https://github.com/antlr/antlr4/blob/master/doc/index.md)
+- [PostgreSQL Grammar Reference](https://github.com/tunnelvisionlabs/antlr4-postgresql)
+
+## Contributing
+
+1. Always add test cases for new features
+2. Follow existing code patterns and conventions
+3. Test against both PostgreSQL and Redshift engines
+4. Use AWS documentation for accurate syntax examples
+5. Ensure all tests pass before submitting changes