initial turing machine

3 files changed, 294 insertions, 36 deletions

diff --git a/turing-machine/js/main.js b/turing-machine/js/main.js
index 68aaa39..9ace6f4 100644
--- a/turing-machine/js/main.js
+++ b/turing-machine/js/main.js
@@ -1,51 +1,24 @@
-const DISPLAY_CELLS = 15;
-const TAPE_LEN = 200;
-
 const MESSAGES = {
   SET_CELL: "SET_CELL",
   PAUSE: "PAUSE",
   SIMULATE: "SIMULATE",
   SET_READER: "SET_READER",
+  NEXT_STEP: "NEXT_STEP",
+  COMPILE: "COMPILE",
+  COMPILE_STATUS: "COMPILE_STATUS",
+  NEW_TURING_STATE: "NEW_TURING_STATE",
 };
 
-class Observable {
-  constructor() {
-    this.observers = [];
-  }
-
-  subscribe(f) {
-    this.observers.push(f);
-  }
-
-  unsubscribe(f) {
-    this.observers = this.observers.filter((subscriber) => subscriber !== f);
-  }
-
-  notify(data) {
-    this.observers.forEach((observer) => observer(data));
-  }
-}
-
 const state = new Observable();
 
-const tape = Array(TAPE_LEN).fill(0);
-state.subscribe((msg) => {
-  if (msg.type == MESSAGES.SET_CELL) {
-    tape[msg.cellId] = msg.value;
-  }
-});
-
-const tapeEl = document.getElementById("tape");
-
 const inputCellId = (cellId) => `${cellId}-input`;
-const updateCellButtonId = (cellId) => `${cellId}-button-update`;
 
 const setCellFromInput = (cellId, inputId) => {
   const input = document.getElementById(inputId);
   tape[cellId] = input.value;
 };
 
-const cell = (cellId, initValue = 0) => {
+const cell = (cellId, initValue = "NULL") => {
   const cellDiv = document.createElement("div");
   cellDiv.classList.add("cell");
   cellDiv.id = cellId;
@@ -85,14 +58,203 @@ const cell = (cellId, initValue = 0) => {
   return cellDiv;
 };
 
+const parseRules = (rules, beginState) => {
+  const quadruples = rules.split("\n");
+
+  const instructions = [];
+  quadruples.forEach((quadruple, line) => {
+    const commentLess = quadruple.replaceAll(/\/\/.*/g, "").trim();
+    if (!commentLess) {
+      return;
+    }
+
+    const items = commentLess
+      .split(" ")
+      .map((x) => x.trim())
+      .filter((x) => x);
+    if (items.length != 4) {
+      throw new Error(`Invalid instruction on line ${line}`);
+    }
+    instructions.push(items);
+  });
+  if (!instructions.some(([fromState]) => fromState == beginState)) {
+    throw new Error(
+      `At least one instruction must begin from state: ${beginState}`
+    );
+  }
+  return instructions;
+};
+
+// --
+
+const tapeEl = document.getElementById("tape");
+const compileButton = document.getElementById("compile");
+const instructionsEl = document.getElementById("instructions");
+const controlsEl = document.getElementById("controls");
+const nextStepButton = document.getElementById("next_step");
+const togglePlayButton = document.getElementById("toggle_play");
+const compileStatusEl = document.getElementById("compile_status");
+const turingMachineStateEl = document.getElementById("turing_state");
+const resetButton = document.getElementById("reset");
+
+resetButton.addEventListener("click", () => {
+  state.notify({ type: MESSAGES.PAUSE });
+  state.notify({ type: MESSAGES.COMPILE, value: instructionsEl.value });
+});
+
+compileButton.addEventListener("click", () => {
+  state.notify({ type: MESSAGES.COMPILE, value: instructionsEl.value });
+});
+
+nextStepButton.addEventListener("click", () => {
+  state.notify({ type: MESSAGES.PAUSE });
+  state.notify({ type: MESSAGES.NEXT_STEP });
+});
+
+let playButton_simulationStatus = "paused";
+togglePlayButton.addEventListener("click", function () {
+  if (playButton_simulationStatus == "paused") {
+    state.notify({ type: MESSAGES.SIMULATE });
+  } else if (playButton_simulationStatus == "simulate") {
+    state.notify({ type: MESSAGES.PAUSE });
+  }
+});
+
+state.subscribe((msg) => {
+  if (msg.type == MESSAGES.COMPILE_STATUS) {
+    const { error, success } = msg;
+    if (error) {
+      compileStatusEl.classList.remove("success");
+      compileStatusEl.classList.add("error");
+      compileStatusEl.innerHTML = error;
+    }
+    if (success) {
+      compileStatusEl.classList.add("success");
+      compileStatusEl.classList.remove("error");
+      compileStatusEl.innerHTML = `Successful compile at ${new Date().toLocaleString()}!`;
+    }
+  }
+});
+
+state.subscribe((msg) => {
+  if (msg.type == MESSAGES.COMPILE_STATUS) {
+    const { error, success } = msg;
+    if (error) {
+      controlsEl.style.display = "none";
+    } else if (success) {
+      controlsEl.style.display = "block";
+    }
+  }
+});
+
+state.subscribe((msg) => {
+  if (msg.type == MESSAGES.PAUSE) {
+    togglePlayButton.innerHTML = "🔁 Begin";
+    playButton_simulationStatus = "paused";
+  }
+  if (msg.type == MESSAGES.SIMULATE) {
+    togglePlayButton.innerHTML = "⏸️ Pause";
+    playButton_simulationStatus = "simulate";
+  }
+});
+
+state.subscribe((msg) => {
+  if (msg.type == MESSAGES.NEW_TURING_STATE) {
+    turingMachineStateEl.innerHTML = msg.value;
+  }
+});
+
+// -
+
 const main = () => {
-  const cells = tape.map((_, cellId) => cell(cellId));
+  const blank = "B";
+  const beginState = "q0";
+  const acceptState = "f";
+  const tape = Array(200).fill(blank);
+  const cells = tape.map((_, cellId) => cell(cellId, blank));
   for (const cell of cells) {
     tapeEl.appendChild(cell);
   }
-  state.notify({ type: MESSAGES.SET_READER, cell: 0 });
 
-  setTimeout(() => {}, 1000);
-};
+  let turingMachine;
+
+  state.subscribe((msg) => {
+    if (msg.type == MESSAGES.SET_CELL) {
+      const { value, cell } = msg;
+      tape[cell] = value;
+      if (turingMachine) turingMachine.setTapeAtCell(cell, value);
+    }
+    if (msg.type == MESSAGES.COMPILE) {
+      const { value } = msg;
+      try {
+        const rules = parseRules(value, beginState, acceptState);
+
+        turingMachine = new TuringMachine(
+          [...tape],
+          rules,
+          beginState,
+          blank,
+          acceptState
+        );
+        state.notify({ type: MESSAGES.SET_READER, cell: 0 });
+        state.notify({
+          type: MESSAGES.NEW_TURING_STATE,
+          value: turingMachine.getStateStatus(),
+        });
+        state.notify({ type: MESSAGES.COMPILE_STATUS, success: true });
+      } catch (e) {
+        state.notify({ type: MESSAGES.COMPILE_STATUS, error: e.toString() });
+      }
+    }
+    if (msg.type == MESSAGES.SIMULATE) {
+      const interval = setInterval(() => {
+        state.notify({ type: MESSAGES.NEXT_STEP });
+      }, 300);
+      const subscriptionFn = (msg) => {
+        if (msg.type == MESSAGES.PAUSE) {
+          clearInterval(interval);
+          state.unsubscribe(subscriptionFn);
+        }
+      };
+      state.subscribe(subscriptionFn);
+    }
+    if (msg.type == MESSAGES.NEXT_STEP && turingMachine) {
+      const step = turingMachine.step();
+
+      const status = turingMachine.getStateStatus();
 
+      const cell = turingMachine.getHead();
+
+      if (!step) {
+        const accepting = turingMachine.isAccepting();
+        state.notify({
+          type: MESSAGES.NEW_TURING_STATE,
+          value: accepting
+            ? `<span class='success'>Accept(${status})</span>`
+            : `<span class='error'>Fail(${status}}</span>`,
+        });
+      } else {
+        state.notify({
+          type: MESSAGES.NEW_TURING_STATE,
+          value: status,
+        });
+      }
+
+      state.notify({
+        type: MESSAGES.SET_READER,
+        cell,
+      });
+      state.notify({
+        type: MESSAGES.SET_CELL,
+        cell,
+        value: turingMachine.getTapeAtCell(cell),
+      });
+
+      if (!step)
+        state.notify({
+          type: MESSAGES.PAUSE,
+        });
+    }
+  });
+};
 main();
diff --git a/turing-machine/js/observable.js b/turing-machine/js/observable.js
new file mode 100644
index 0000000..1299fc6
--- /dev/null
+++ b/turing-machine/js/observable.js
@@ -0,0 +1,14 @@
+class Observable {
+  constructor() {
+    this.observers = [];
+  }
+  subscribe(f) {
+    this.observers.push(f);
+  }
+  unsubscribe(f) {
+    this.observers = this.observers.filter((subscriber) => subscriber !== f);
+  }
+  notify(data) {
+    this.observers.forEach((observer) => observer(data));
+  }
+}
diff --git a/turing-machine/js/turing_machine.js b/turing-machine/js/turing_machine.js
new file mode 100644
index 0000000..9c21983
--- /dev/null
+++ b/turing-machine/js/turing_machine.js
@@ -0,0 +1,82 @@
+class TuringMachine {
+  constructor(
+    tape = [],
+    rules = [],
+    initialState = "q0",
+    blankSymbol = "B",
+    acceptState = "f"
+  ) {
+    this.tape = tape;
+    this.rules = this.parseRules(rules);
+    this.state = initialState;
+    this.head = 0;
+    this.blankSymbol = blankSymbol;
+    this.acceptState = acceptState;
+
+    this.iteration = 0;
+  }
+
+  getStateStatus() {
+    return `State: ${this.state}, Step: ${this.iteration}`;
+  }
+
+  getHead() {
+    return this.head;
+  }
+
+  getState() {
+    return this.state;
+  }
+
+  getTapeAtCell(idx) {
+    return this.tape[idx];
+  }
+
+  setTapeAtCell(idx, val) {
+    this.tape[idx] = val;
+  }
+
+  isAccepting() {
+    return this.state == this.acceptState;
+  }
+
+  parseRules(rules) {
+    const parsedRules = {};
+    for (const [currentState, readSymbol, action, newState] of rules) {
+      const key = `${currentState},${readSymbol}`;
+      const value = `${newState},${action}`;
+      parsedRules[key] = value;
+    }
+    return parsedRules;
+  }
+
+  step() {
+    const currentSymbol = this.tape[this.head] || this.blankSymbol;
+    const key = `${this.state},${currentSymbol}`;
+    if (!(key in this.rules)) {
+      return false;
+    }
+    const rule = this.rules[key];
+    const [newState, action] = rule.split(",");
+
+    this.state = newState;
+
+    if (action === "R") {
+      this.head += 1;
+    } else if (action === "L") {
+      this.head -= 1;
+    } else {
+      this.tape[this.head] = action;
+    }
+
+    if (this.isAccepting()) {
+      return false;
+    }
+
+    if (this.head >= 0 && this.head < this.tape.length) {
+      this.iteration++;
+      return true;
+    }
+    return false;
+  }
+}