AST-Printer

A simple pseudo-C++ parser and AST visualizer, written in C++17 as part of the Formal Approaches, Languages, and Compilers course project.

This tool reads source code written in a simplified C++-like syntax,
performs lexical and syntax analysis, builds an * *Abstract Syntax Tree (AST)**, and prints the result in a readable tree structure.

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🧩 Project Structure

AST-Printer/
├── Include/
│   ├── ast.hpp          # AST node class definitions
│   ├── parser.hpp       # Parser class declaration
│   └── tokens.hpp       # Token structure and type definitions
├── src/
│   ├── main.cpp         # Entry point: connects scanner, parser, and AST printer
│   ├── parser.cpp       # Recursive-descent parser implementation
│   └── scanner.l        # Flex-based lexical analyzer
├── CMakeLists.txt       # Build configuration
└── read.txt             # Example input file

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⚙️ Build & Run

Requirements

• C++17 or later
• CMake ≥ 3.16
• Flex (for lexical analysis)
• Unix or Unix-like System

Steps

# 1. Clone the repository
git clone https://github.com/ISEP-Projects-JH/AST-Printer.git
cd AST-Printer

# 2. Build
mkdir build && cd build
cmake ..
cmake --build .

# 3. Run
./compiler

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📄 Example Input (read.txt)

int Va = 5;
int Vb = 2;
Va = Va + Vb;
print(Va);
END

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🌳 Example Output

Tokens:
int Va = 5 ; int Vb = 2 ; Va = Va + Vb ; print ( Va ) ; END 

AST:
└── Statement
    ├── Statement
    │   ├── Statement
    │   │   ├── Statement
    │   │   │   └── Declaration (int)
    │   │   │       ├── Identifier: Va
    │   │   │       └── Number: 5
    │   │   └── Declaration (int)
    │   │       ├── Identifier: Vb
    │   │       └── Number: 2
    │   └── Assignment (=)
    │       ├── Identifier: Va
    │       └── BinOp (+)
    │           ├── Identifier: Va
    │           └── Identifier: Vb
    └── Print
        └── Identifier: Va

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🧠 Key Concepts

• Lexical Analysis using Flex to tokenize pseudo-C++ syntax.
• Recursive Descent Parsing to apply grammar rules and verify syntax.
• AST Construction with node classes (BinOpNode, Declaration, Assignment, etc.).
• Tree Visualization using depth-first traversal in main.cpp.

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📘 Grammar Summary

Program        := Statements END
Statements     := Statement Statements | ε
Statement      := Declaration | Assignment | IfStatement | WhileStatement | PrintStatement
Declaration    := (int | string) Var [= Expr] ;
Assignment     := Var = Expr ;
PrintStatement := print ( Expr ) ;
Expr           := Term { ("+" | "-") Term }
Term           := Factor { ("*" | "/") Factor }
Factor         := IntLit | StringLit | Var | "(" Expr ")"

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🧾 License

This project is released for educational purposes under the MIT License.

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🧑‍💻 Author

JeongHan Bae GitHub Profile
Course Project Repository: ISEP-Projects-JH/AST-Printer