TestInterpreter

A modern C++17 interpreter for a small, dynamically typed, expression-oriented language.
Inspired by Crafting Interpreters but reimplemented with RAII, std::variant, smart pointers, and idiomatic STL usage for memory safety and clarity.

Features

✅ Implemented

• Lexical Analysis (lexer.h / lexer.cpp)
  • Tokenizes source into a stream of Token objects.
  • Supports identifiers, keywords, numbers, strings, operators, grouping, and blocks.
  • Recognizes reserved keywords (if, else, while, fun, return, var, print, etc.).
• Parser (parser.h / parser.cpp)
  • Recursive descent parser with correct operator precedence.
  • Handles:
    • Literals (number, string, true, false, nil)
    • Unary/binary operations (-, +, *, /, !, comparisons, equality)
    • Variable declarations & assignments
    • Blocks and nested scopes
    • Conditional statements (if / else)
    • Loops (while)
    • Function declarations and calls (with closures)
    • return statements
    • print statements
• AST Evaluation (expr.*, stmt.*)
  • Expression and statement execution with runtime type checks.
  • Supports first-class functions with lexical scoping.
• Environments (environment.*)
  • Lexical scoping via chained environments.
  • Variable definition, lookup, and reassignment.
• REPL & File Execution (main.cpp)
  • Interactive prompt for quick experimentation.
  • Script execution from file.

🚧 Planned

• Better error recovery (currently halts on first error).
• Grouping expression AST node.
• More built-in functions.
• Improved number formatting.

---

Example

Source

fun my_fun() {
  var a = "inner";
  print a;
}

var a = "outer";
my_fun();
print a;

Output

Tokens:
Type: FUNCTION   Lexeme: 'fun'
...
true
outer

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Build Instructions

Prerequisites

• CMake ≥ 3.10
• C++17 compiler (GCC, Clang, or MSVC)

Steps

git clone https://github.com/luckyayush777/TestInterpreter.git
cd TestInterpreter
mkdir build && cd build
cmake ..
make

---

Running

Interactive Mode (REPL)

./TestInterpreter

Run from File

./TestInterpreter path/to/script.txt

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Project Structure

TestInterpreter/
├── CMakeLists.txt
├── include/
│   ├── callable.h
│   ├── environment.h
│   ├── expr.h
│   ├── function.h
│   ├── lexer.h
│   ├── parser.h
│   ├── stmt.h
│   ├── token.h
│   └── util.h
├── src/
│   ├── environment.cpp
│   ├── expr.cpp
│   ├── function.cpp
│   ├── lexer.cpp
│   ├── main.cpp
│   ├── parser.cpp
│   ├── stmt.cpp
│   └── util.cpp
├── test.txt
└── README.md

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License

MIT License — free to use, modify, and distribute.