CRUST

C/C++ to Rust Transpiler

CRUST is a command-line transpiler that converts C/C++ syntax into Rust code. It aims to reduce migration effort while preserving semantics with safe, auditable output.

Highlights

• Converts declarations, assignments, and basic expressions
• Supports control flow: if / if-else, while, for, switch
• Handles basic struct/union/class definitions
• Preserves comments and outputs warning markers for unsupported constructs
• Strict (-s) vs loose mode (default) semantics for variable mutability

Works best for small/medium C++ code slices. Complex constructs (templates, macros, function pointers) are partially supported and may require manual adjustments.

---

Quick Start

1) Install Rust

curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh
source $HOME/.cargo/env
rustc --version

2) Clone the repository

git clone https://github.com/nishanthspshetty/crust.git
cd crust

3) Build

cargo build

4) Run

cargo run -- examples/prog.cpp

Interactive prompts:

• Enter the C/C++ file to be converted to Rust : examples/prog.cpp
• Enter the translation mode [(S/s)trict/(L/l)oose] : l
• Do you want to create a cargo project :[Y/N] n

Output is written to examples/prog.rs by default (or <project>/src/main.rs if project creation is selected).

---

CLI Options

cargo run -- -s -p myproj examples/main.cpp

• -s, --strict: strict mode (immutable bindings)
• -p, --project-name: create a new Cargo project and write to project/src/main.rs
• -h, --help: display usage information

---

Testing

Run the full test suite:

cargo test

Key test locations:

• src/library/parser/parser_test.rs
• src/library/lexer/tokenizer/*

Recent test additions

• full expression output validation for declarations and expressions
• parser bounds-safe checks to avoid index panics
• strict/loose mode behavior tests

---

Developer Documentation

Architecture

• src/main.rs: CLI + orchestration + file I/O
• src/library/lexer: tokenization pipeline
• src/library/parser: recursive descent translation engine

Parser flow

1. Tokenize input into Vec<Token>
2. init_parser processes with Parser state
3. parse_program dispatches to specialized handlers (control flow, types, assignments)
4. Build Rust token stream and output text

Coding standards

• avoid Vec cloning; use &[Token] slices
• avoid expect in parser production paths; use Result with structured errors next
• enforce cargo fmt, cargo clippy

Local dev workflow

cargo test
cargo fmt --all
cargo clippy -- -D warnings

---

Supported Features

• Types: int, float, char, const, unsigned, pointers
• Control structures: if, if-else, while, for, switch
• typedef, struct, union, class, enum
• Comments preserved (as // or /* */ blocks)

Limitations

• templates, generic C++ constructs
• function pointers and functors
• macros with preprocessor logic
• comprehensive standard library conversion (e.g., iostream / std::vector)

---

Release Notes (latest)

• fixed Cargo metadata (exclude in [package])
• enabled robust parser bounds safety
• added full-expression tests for parser outputs
• expanded README with user + developer details, badges, screenshot placeholder

---

Contributing

1. Fork repository
2. branch: feature/<name>
3. Add/update tests in src/library/parser/parser_test.rs
4. cargo test and cargo fmt
5. PR with summary of behavior regressions/improvements

---

License

MIT