rslox

This repository is an example implementation of the lox programming language, following the steps described in the book "Crafting Interpreters" by Robert Nystrom.

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🚀 How to Use

⚠️ Development Alias Recommendation

Since the project is currently in development, it's convenient to create an alias for cargo run -q -- to speed up testing.

Add the following to your shell configuration file (e.g., .bashrc, .zshrc):

alias crq='cargo run -q --'

Once added, you can use crq instead of cargo run -q -- in the commands below.

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📖 Show Help

To display the help message with available commands and options:

crq --help 

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💻 Interactive Mode (REPL)

To start the interpreter in interactive mode:

crq run

This launches a REPL where you can type and execute code interactively.

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📂 Run From a File

To execute code from a .lox file:

crq run -p <file_path>

Replace <file_path> with the path to your .lox file.

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🐛 Debug Mode

To run in debug mode, which can optionally display tokens, the AST, or both:

crq run --debug

You can control what to display:

crq run --debug --show-ast
crq run --debug --show-tokens
crq run --debug --show-ast --show-tokens

✅ These options also work in interactive mode:

crq run --debug --show-ast

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🛠️ Tools

Additional tools are available via the tool command:

crq tool <subcommand>

Available subcommands:

• gen-ast — Generates internal AST data structures

Example:

crq tool gen-ast

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📋 Current Features

📝 Scanner

• Single-character tokens: ( ) { } , . - + ; / *
• One or two-character tokens: ! != = == > >= < <=
• Literals:
  • Identifiers
  • Numbers
  • Strings
• Keywords:
  and, class, else, false, fun, for, if, nil, or, print, return, super, this, true, var, while
• Single-line comments: // ...
• Block comments: /* ... */
• Emits an EOF token at the end of input
• Error handling for:
  • Invalid tokens

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🌳 Parser

• Parses arithmetic expressions with +, -, *, /
• Respects operator precedence and associativity
• Supports grouping with parentheses ()
• Generates an Abstract Syntax Tree (AST) for valid arithmetic expressions
• Error handling for:
  • Invalid tokens
  • Syntax errors
  • Unsupported keywords
• 🚫 No parsing for logic operators (and, or) yet
• 🚫 No support for statements, declarations, or control structures yet

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💻 Command Line Interface (CLI)

• run — Runs a .lox file or starts a REPL
  • --debug — Activates a debug mode with optional output controls
  • --show-ast — Shows the AST for each input
  • --show-tokens — Shows the list of tokens for each input
• tool — Executes development tools:
  • gen-ast
• Colored output and enhanced CLI feedback

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🖨️ Output

• Prints the AST and/or tokens based on selected options
• 🚫 No expression evaluation or runtime execution yet