Turing Machine Simulator

A simple command-line Turing machine simulator written in Rust.
It reads a transition table from a text file, asks for an input string, and simulates the machine until it halts.

Table of Contents

• Build & Run
• Input File Format
• Features
• Implementation Notes
• Roadmap

Build & Run

Build and run with cargo

cargo run -- <input file>

Input File Format

• The first line lists the final (accepting) states, comma-separated.
• Each subsequent line defines a transition in the format:

(current_state, read_symbol) -> (next_state, write_symbol, direction)

• direction can be either < (move left) or > (move right)
• _ represents a blank cell

Features

• Parses Turing machine transition definitions from a plain text file
• Uses a hash map for the transition table for fast lookups
• Interactive simulation with live tape updates
• Accept/reject halts based on final states

Implementation Notes

• Tape length = 256 cells with wraparound
• All uninitialized tape cells are _
• Simulator starts in state q0 and halts when no valid transition exists
• If the current state is in the list of final states, the machine accepts; otherwise, it halts with an error

Roadmap

• Parse input files and run the machine
• Instantaneous description
• Turing machine variants