SNOL Interpreter

A modular interpreter for the Simple Number-Only Language (SNOL) — a case-sensitive, minimalistic language that supports only integer and real number operations. Designed as a structured programming project to demonstrate key compiler/interpreter components.

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📌 Objective

To implement a functioning interpreter for SNOL by breaking down the system into independent, structured components (lexer, parser, evaluator, etc.) and coordinating them in a clean control loop.

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🧠 Language Overview (SNOL)

SNOL supports:

• Integer and floating-point literals
• Arithmetic operations (+, -, *, /, %)
• Variable assignment and type inference
• Input (BEG var) and output (PRINT var)
• Exit command (EXIT!) to terminate the interpreter

🔤 Sample Commands

num = 0
PRINT num         # Output: [num] = 0
BEG value         # Prompts user for input
value + 5         # Arithmetic expression
EXIT!             # Terminates interpreter

✅ Features

• Validates variable definitions and usage
• Supports basic error handling:
  • Undefined variables
  • Type mismatches
  • Invalid command syntax
  • Unknown or invalid tokens
• Input validation (ensures correct numeric format)
• Mimics command-line REPL interface

🧱 Modular Structure

• main.py:
  • Interpreter Control Loop: Entry point. Reads user input, coordinates all modules, and manages the REPL and EXIT! command.
• tokenizer.py:
  • Tokenizer: Converts raw input into a list of tokens (keywords, literals, operators). Enforces syntax and token rules.
  • Syntax Validator: Parses token lists to recognize SNOL grammar. Returns structured data or errors.
• symbol_table.py:
  • Variable Manager: Stores variables with types (int/float). Handles assignments, lookups, and reassignments.
• evaluator.py:
  • Arithmetic Evaluator: Computes results from parsed expressions using correct precedence and type checks.
• io_handler.py:
  • I/O Manager: Handles BEG var for input and PRINT commands for output formatting and variable lookups.

🧑‍🤝‍🧑 Member Feature Area Responsibility

• Lexical Analyzer
  • Built the tokenizer (lexer.py) to clean and break input into valid tokens.
• Syntax Validator
  • Designed the parser to understand and structure SNOL commands (parser.py).
• Symbol Table Manager
  • Developed the variable tracking system (symbol_table.py) with type inference.
• Expression Evaluator
  • Handled arithmetic computations with error handling (evaluator.py).
• I/O + REPL Loop
  • Created the main control loop and I/O management (main.py, io_handler.py).

🚀 How to Run

(To be followed)

📂 Project Structure

Project_SNOL/
├── main.py              # REPL loop and coordinator
├── lexer.py             # Tokenizer
├── parser.py            # Syntax analyzer
├── symbol_table.py      # Variable manager
├── evaluator.py         # Arithmetic processor
├── io_handler.py        # Input/output handlers
├── README.md            # Project documentation

Git Workflow

1. Checkout a Branch To checkout a branch, follow these steps:

List branches: To see all available branches, run:

Checkout a branch: To switch to an existing branch, run:
git checkout <branch-name>

2. Committing Changes

git add <specific file>
or
git add .

Commit Message Format Please use:

git commit -m "<feature>(<assignedFeature>): <short-description>"
or
git commit -m "<fix>(<assignedFeature>): <short-description>"

Push your changes to your feature branch

git push origin feature/branchname