commit 522f33b221b7ad0d14e2bde9e4fe04ca0137bced
Author: Timo Schneider <timoschneider04@gmail.com>
Date:   Thu Mar 21 16:00:41 2024 +0100

    Added Turing machine

diff --git a/.gitignore b/.gitignore
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--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,2 @@
+/target
+/Cargo.lock
diff --git a/Cargo.toml b/Cargo.toml
new file mode 100644
index 0000000..6ae5a6c
--- /dev/null
+++ b/Cargo.toml
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+[package]
+name = "turing_machine"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
diff --git a/src/main.rs b/src/main.rs
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index 0000000..263a495
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+++ b/src/main.rs
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+use crate::turing::*;
+
+mod turing;
+
+// length of the turing machine belt
+const LENGTH: usize = 64;
+
+fn main() {
+    let mut machine = TuringMachine::new();
+
+    // config turing machine belt
+    machine.set_belt(1, Value::Hash);
+    machine.set_belt(2, Value::One);
+    machine.set_belt(3, Value::One);
+    machine.set_belt(4, Value::One);
+    machine.set_belt(5, Value::One);
+    machine.set_belt(6, Value::Hash);
+    machine.set_belt(7, Value::One);
+    machine.set_belt(8, Value::One);
+    machine.set_belt(9, Value::One);
+    machine.set_belt(10, Value::Hash);
+
+
+    // config state transitions
+    machine.set_transition(0, Value::Hash, 1);
+    machine.set_transition(1, Value::Hash, 2);
+    machine.set_transition(2, Value::Hash, 3);
+    machine.set_transition(3, Value::One, 4);
+    machine.set_transition(4, Value::Hash, 5);
+    machine.set_transition(5, Value::Hash, 6);
+    machine.set_transition(6, Value::One, 1);
+    machine.set_transition(7, Value::One, 1);
+    machine.set_transition(7, Value::Hash, 1);
+    machine.set_transition(3, Value::Hash, 8);
+    machine.set_transition(8, Value::Hash, 9);
+
+
+    // config state actions
+    machine.set_actions(0, Value::None, Action {direction: Direction::Right, value: Value::None});
+    machine.set_actions(0, Value::Hash, Action {direction: Direction::Right, value: Value::Hash});
+    machine.set_actions(1, Value::One, Action {direction: Direction::Right, value: Value::One});
+    machine.set_actions(1, Value::Hash, Action {direction: Direction::Right, value: Value::Hash});
+    machine.set_actions(2, Value::One, Action {direction: Direction::Right, value: Value::One});
+    machine.set_actions(2, Value::Hash, Action {direction: Direction::Left, value: Value::None});
+    machine.set_actions(3, Value::One, Action {direction: Direction::Left, value: Value::Hash});
+    machine.set_actions(3, Value::Hash, Action {direction: Direction::Left, value: Value::Hash});
+    machine.set_actions(4, Value::One, Action {direction: Direction::Left, value: Value::One});
+    machine.set_actions(4, Value::Hash, Action {direction: Direction::Left, value: Value::Hash});
+    machine.set_actions(5, Value::One, Action {direction: Direction::Left, value: Value::One});
+    machine.set_actions(5, Value::Hash, Action {direction: Direction::Right, value: Value::None});
+    machine.set_actions(6, Value::One, Action {direction: Direction::Right, value: Value::Hash});
+    machine.set_actions(8, Value::One, Action {direction: Direction::Left, value: Value::One});
+    machine.set_actions(8, Value::Hash, Action {direction: Direction::Quit, value: Value::Hash});
+
+
+    // start machine
+    machine.start();
+}
diff --git a/src/turing.rs b/src/turing.rs
new file mode 100644
index 0000000..80e25d5
--- /dev/null
+++ b/src/turing.rs
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+use std::collections::HashMap;
+use std::hash::Hash;
+use std::process::exit;
+use std::time::Instant;
+use crate::LENGTH;
+
+// all values possible in a turing machine
+#[derive(Copy, Clone, Eq, PartialOrd, PartialEq, Hash)]
+pub enum Value {
+    // Zero,
+    One,
+    Hash,
+    None,
+}
+
+// all directions the pointer can go
+#[derive(Copy, Clone, Eq, PartialOrd, PartialEq, Hash)]
+pub enum Direction {
+    Left,
+    Right,
+    Quit,
+}
+
+// an action that can be made
+#[derive(Copy, Clone, Eq, PartialOrd, PartialEq, Hash)]
+pub struct Action {
+    pub direction: Direction,
+    pub value: Value,
+}
+
+// the turing machine
+pub struct TuringMachine {
+    belt: [Value; LENGTH],
+    pointer: usize,
+    state: u64,
+    state_next: u64,
+    transitions: HashMap<u64, HashMap<Value, u64>>,
+    actions: HashMap<u64, HashMap<Value, Action>>,
+}
+
+impl TuringMachine {
+    // create a new turing machine
+    pub fn new() -> Self {
+        // return empty turing machine
+        return TuringMachine {
+            belt: [Value::None; LENGTH],
+            pointer: 0,
+            state: 0,
+            state_next: 0,
+            transitions: HashMap::new(),
+            actions: HashMap::new(),
+        };
+    }
+
+    pub fn set_belt(&mut self, index: usize, value: Value) -> () {
+        // set value on belt
+        self.belt[index] = value;
+    }
+
+    pub fn set_transition(&mut self, state: u64, value: Value, next_state: u64) -> () {
+        // If the State is not in the HashMap, add it
+        if self.transitions.get(&state).is_none() {
+            self.transitions.insert(state, HashMap::new());
+        }
+
+        // get the inner HashMap with the next state
+        let mut state_transition: HashMap<Value, u64> = self.transitions.get(&state).unwrap().to_owned();
+        // update inner HashMap
+        state_transition.insert(value, next_state);
+        // update outer HashMap
+        self.transitions.insert(state, state_transition);
+    }
+
+    pub fn set_actions(&mut self, state: u64, value: Value, output: Action) -> () {
+        // If the State is not in the HashMap, add it
+        if self.actions.get(&state).is_none() {
+            self.actions.insert(state, HashMap::new());
+        }
+
+        // get the inner HashMap with the action
+        let mut state_action: HashMap<Value, Action> = self.actions.get(&state).unwrap().to_owned();
+        // update inner HashMap
+        state_action.insert(value, output);
+        // update outer HashMap
+        self.actions.insert(state, state_action);
+    }
+
+    fn print(&self) -> () {
+        // clear console
+        print!("{esc}[2J{esc}[1;1H", esc = 27 as char);
+
+        // create empty string for line
+        let mut line = String::new();
+
+        // iterate trough belt and add the values to the string
+        for value in self.belt {
+            line += match value {
+                // Value::Zero => {" 0"},
+                Value::One  => {" 1"},
+                Value::Hash => {" #"},
+                Value::None => {" u"},
+            }
+        }
+        // print the belt
+        println!("{}", line);
+
+        // reset the line
+        line = String::new();
+
+        // add two space for every state, except for one
+        for _ in 0..2*self.belt.len()-1 {
+            line += " ";
+        }
+
+        // insert the pointer to the current location in belt
+        line.insert(2*self.pointer + 1, '^');
+
+        // print pointer
+        println!("{}", line);
+    }
+
+    fn get(&self) -> Value {
+        // get the current value from the belt
+        return self.belt[self.pointer];
+    }
+
+    fn target_next_transition(&mut self) -> () {
+        // verify there is the state
+        if self.transitions.get(&self.state).is_none() {
+            // the state won't switch
+            self.state_next = self.state;
+            return;
+        }
+        // verify there is a transition for the current symbol
+        if self.transitions.get(&self.state).unwrap().get(&self.get()).is_some() {
+            // set next state based on config
+            self.state_next = self.transitions.get(&self.state).unwrap().get(&self.get()).unwrap().to_owned();
+        }
+    }
+
+    fn make_action(&mut self) -> Result<(), ()> {
+        // verify there is the state
+        if self.actions.get(&self.state).unwrap().get(&self.get()).is_some() {
+            // make action
+            return self.execute(self.actions.get(&self.state).unwrap().get(&self.get()).unwrap().to_owned());
+        }
+        // action successful
+        return Ok(());
+    }
+
+    fn execute(&mut self, action: Action) -> Result<(), ()> {
+        // update belt value at pointer
+        self.belt[self.pointer] = action.value;
+
+        // move pointer or exit
+        match action.direction {
+            Direction::Left => {if self.pointer > 0 {self.pointer -= 1} else {panic!("Index out of bounds")}}
+            Direction::Right => {if self.pointer < LENGTH {self.pointer += 1} else {panic!("Index out of bounds")}}
+            Direction::Quit => {return Err(())}
+        }
+        // pointer moved successfully
+        return Ok(());
+    }
+
+    fn transition(&mut self) -> () {
+        // switch to the next state
+        self.state = self.state_next;
+    }
+
+    pub fn start(&mut self) -> ! {
+        // Allocate Space for Instant
+        let mut start: Instant;
+
+        // loop until program finishes
+        'operation: loop {
+            // track loop start time
+             start = Instant::now();
+
+            // choose next transition
+            self.target_next_transition();
+
+            // make next action. An Error is an alias for quit
+            if self.make_action().is_err() {
+                break 'operation;
+            }
+
+            // make transition
+            self.transition();
+
+            // print current state
+            self.print();
+
+            // wait for readability
+            while start.elapsed().as_millis() < 100 {};
+        }
+
+        // quit program
+        exit(0);
+    }
+}
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