index.html

@@ -44,6 +44,17 @@
           </div>
         </a>
 
+        <a class="project" href="/turing-machine/">
+          <div class="project-logo-container">
+            <i class="fa-solid fa-tape"></i>
+          </div>
+
+          <div class="project-body">
+            <h1>Simponic's State System</h1>
+            <p>A Turing Machine simulator specific to CS5000.</p>
+          </div>
+        </a>
+
         <a class="project" href="/julia/">
           <div class="project-logo-container">
             <i class="fa-solid fa-square-root-variable"></i>

turing-machine/codemirror/codemirror.css

@@ -0,0 +1,488 @@
+/* BASICS */
+
+.CodeMirror {
+  /* Set height, width, borders, and global font properties here */
+  font-family: monospace !important;
+  height: 300px;
+  color: black;
+  direction: ltr;
+}
+
+/* PADDING */
+
+.CodeMirror-lines {
+  padding: 4px 0; /* Vertical padding around content */
+}
+.CodeMirror pre.CodeMirror-line,
+.CodeMirror pre.CodeMirror-line-like {
+  padding: 0 4px; /* Horizontal padding of content */
+}
+
+.CodeMirror-scrollbar-filler,
+.CodeMirror-gutter-filler {
+  background-color: white; /* The little square between H and V scrollbars */
+}
+
+/* GUTTER */
+
+.CodeMirror-gutters {
+  border-right: 1px solid #ddd;
+  background-color: #f7f7f7;
+  white-space: nowrap;
+}
+.CodeMirror-linenumbers {
+}
+.CodeMirror-linenumber {
+  padding: 0 3px 0 5px;
+  min-width: 20px;
+  text-align: right;
+  color: #999;
+  white-space: nowrap;
+}
+
+.CodeMirror-guttermarker {
+  color: black;
+}
+.CodeMirror-guttermarker-subtle {
+  color: #999;
+}
+
+/* CURSOR */
+
+.CodeMirror-cursor {
+  border-left: 1px solid black;
+  border-right: none;
+  width: 0;
+}
+/* Shown when moving in bi-directional text */
+.CodeMirror div.CodeMirror-secondarycursor {
+  border-left: 1px solid silver;
+}
+.cm-fat-cursor .CodeMirror-cursor {
+  width: auto;
+  border: 0 !important;
+  background: #7e7;
+}
+.cm-fat-cursor div.CodeMirror-cursors {
+  z-index: 1;
+}
+.cm-fat-cursor .CodeMirror-line::selection,
+.cm-fat-cursor .CodeMirror-line > span::selection,
+.cm-fat-cursor .CodeMirror-line > span > span::selection {
+  background: transparent;
+}
+.cm-fat-cursor .CodeMirror-line::-moz-selection,
+.cm-fat-cursor .CodeMirror-line > span::-moz-selection,
+.cm-fat-cursor .CodeMirror-line > span > span::-moz-selection {
+  background: transparent;
+}
+.cm-fat-cursor {
+  caret-color: transparent;
+}
+@-moz-keyframes blink {
+  0% {
+  }
+  50% {
+    background-color: transparent;
+  }
+  100% {
+  }
+}
+@-webkit-keyframes blink {
+  0% {
+  }
+  50% {
+    background-color: transparent;
+  }
+  100% {
+  }
+}
+@keyframes blink {
+  0% {
+  }
+  50% {
+    background-color: transparent;
+  }
+  100% {
+  }
+}
+
+/* Can style cursor different in overwrite (non-insert) mode */
+.CodeMirror-overwrite .CodeMirror-cursor {
+}
+
+.cm-tab {
+  display: inline-block;
+  text-decoration: inherit;
+}
+
+.CodeMirror-rulers {
+  position: absolute;
+  left: 0;
+  right: 0;
+  top: -50px;
+  bottom: 0;
+  overflow: hidden;
+}
+.CodeMirror-ruler {
+  border-left: 1px solid #ccc;
+  top: 0;
+  bottom: 0;
+  position: absolute;
+}
+
+/* DEFAULT THEME */
+
+.cm-s-default .cm-header {
+  color: blue;
+}
+.cm-s-default .cm-quote {
+  color: #090;
+}
+.cm-negative {
+  color: #d44;
+}
+.cm-positive {
+  color: #292;
+}
+.cm-header,
+.cm-strong {
+  font-weight: bold;
+}
+.cm-em {
+  font-style: italic;
+}
+.cm-link {
+  text-decoration: underline;
+}
+.cm-strikethrough {
+  text-decoration: line-through;
+}
+
+.cm-s-default .cm-keyword {
+  color: #708;
+}
+.cm-s-default .cm-atom {
+  color: #219;
+}
+.cm-s-default .cm-number {
+  color: #164;
+}
+.cm-s-default .cm-def {
+  color: #00f;
+}
+.cm-s-default .cm-variable,
+.cm-s-default .cm-punctuation,
+.cm-s-default .cm-property,
+.cm-s-default .cm-operator {
+}
+.cm-s-default .cm-variable-2 {
+  color: #05a;
+}
+.cm-s-default .cm-variable-3,
+.cm-s-default .cm-type {
+  color: #085;
+}
+.cm-s-default .cm-comment {
+  color: #a50;
+}
+.cm-s-default .cm-string {
+  color: #a11;
+}
+.cm-s-default .cm-string-2 {
+  color: #f50;
+}
+.cm-s-default .cm-meta {
+  color: #555;
+}
+.cm-s-default .cm-qualifier {
+  color: #555;
+}
+.cm-s-default .cm-builtin {
+  color: #30a;
+}
+.cm-s-default .cm-bracket {
+  color: #997;
+}
+.cm-s-default .cm-tag {
+  color: #170;
+}
+.cm-s-default .cm-attribute {
+  color: #00c;
+}
+.cm-s-default .cm-hr {
+  color: #999;
+}
+.cm-s-default .cm-link {
+  color: #00c;
+}
+
+.cm-s-default .cm-error {
+  color: #f00;
+}
+.cm-invalidchar {
+  color: #f00;
+}
+
+.CodeMirror-composing {
+  border-bottom: 2px solid;
+}
+
+/* Default styles for common addons */
+
+div.CodeMirror span.CodeMirror-matchingbracket {
+  color: #0b0;
+}
+div.CodeMirror span.CodeMirror-nonmatchingbracket {
+  color: #a22;
+}
+.CodeMirror-matchingtag {
+  background: rgba(255, 150, 0, 0.3);
+}
+.CodeMirror-activeline-background {
+  background: #e8f2ff;
+}
+
+/* STOP */
+
+/* The rest of this file contains styles related to the mechanics of
+   the editor. You probably shouldn't touch them. */
+
+.CodeMirror {
+  position: relative;
+  overflow: hidden;
+  background: white;
+}
+
+.CodeMirror-scroll {
+  overflow: scroll !important; /* Things will break if this is overridden */
+  /* 50px is the magic margin used to hide the element's real scrollbars */
+  /* See overflow: hidden in .CodeMirror */
+  margin-bottom: -50px;
+  margin-right: -50px;
+  padding-bottom: 50px;
+  height: 100%;
+  outline: none; /* Prevent dragging from highlighting the element */
+  position: relative;
+  z-index: 0;
+}
+.CodeMirror-sizer {
+  position: relative;
+  border-right: 50px solid transparent;
+}
+
+/* The fake, visible scrollbars. Used to force redraw during scrolling
+   before actual scrolling happens, thus preventing shaking and
+   flickering artifacts. */
+.CodeMirror-vscrollbar,
+.CodeMirror-hscrollbar,
+.CodeMirror-scrollbar-filler,
+.CodeMirror-gutter-filler {
+  position: absolute;
+  z-index: 6;
+  display: none;
+  outline: none;
+}
+.CodeMirror-vscrollbar {
+  right: 0;
+  top: 0;
+  overflow-x: hidden;
+  overflow-y: scroll;
+}
+.CodeMirror-hscrollbar {
+  bottom: 0;
+  left: 0;
+  overflow-y: hidden;
+  overflow-x: scroll;
+}
+.CodeMirror-scrollbar-filler {
+  right: 0;
+  bottom: 0;
+}
+.CodeMirror-gutter-filler {
+  left: 0;
+  bottom: 0;
+}
+
+.CodeMirror-gutters {
+  position: absolute;
+  left: 0;
+  top: 0;
+  min-height: 100%;
+  z-index: 3;
+}
+.CodeMirror-gutter {
+  white-space: normal;
+  height: 100%;
+  display: inline-block;
+  vertical-align: top;
+  margin-bottom: -50px;
+}
+.CodeMirror-gutter-wrapper {
+  position: absolute;
+  z-index: 4;
+  background: none !important;
+  border: none !important;
+}
+.CodeMirror-gutter-background {
+  position: absolute;
+  top: 0;
+  bottom: 0;
+  z-index: 4;
+}
+.CodeMirror-gutter-elt {
+  position: absolute;
+  cursor: default;
+  z-index: 4;
+}
+.CodeMirror-gutter-wrapper ::selection {
+  background-color: transparent;
+}
+.CodeMirror-gutter-wrapper ::-moz-selection {
+  background-color: transparent;
+}
+
+.CodeMirror-lines {
+  cursor: text;
+  min-height: 1px; /* prevents collapsing before first draw */
+}
+.CodeMirror pre.CodeMirror-line,
+.CodeMirror pre.CodeMirror-line-like {
+  /* Reset some styles that the rest of the page might have set */
+  -moz-border-radius: 0;
+  -webkit-border-radius: 0;
+  border-radius: 0;
+  border-width: 0;
+  background: transparent;
+  font-family: inherit;
+  font-size: inherit;
+  margin: 0;
+  white-space: pre;
+  word-wrap: normal;
+  line-height: inherit;
+  color: inherit;
+  z-index: 2;
+  position: relative;
+  overflow: visible;
+  -webkit-tap-highlight-color: transparent;
+  -webkit-font-variant-ligatures: contextual;
+  font-variant-ligatures: contextual;
+}
+.CodeMirror-wrap pre.CodeMirror-line,
+.CodeMirror-wrap pre.CodeMirror-line-like {
+  word-wrap: break-word;
+  white-space: pre-wrap;
+  word-break: normal;
+}
+
+.CodeMirror-linebackground {
+  position: absolute;
+  left: 0;
+  right: 0;
+  top: 0;
+  bottom: 0;
+  z-index: 0;
+}
+
+.CodeMirror-linewidget {
+  position: relative;
+  z-index: 2;
+  padding: 0.1px; /* Force widget margins to stay inside of the container */
+}
+
+.CodeMirror-widget {
+}
+
+.CodeMirror-rtl pre {
+  direction: rtl;
+}
+
+.CodeMirror-code {
+  outline: none;
+}
+
+/* Force content-box sizing for the elements where we expect it */
+.CodeMirror-scroll,
+.CodeMirror-sizer,
+.CodeMirror-gutter,
+.CodeMirror-gutters,
+.CodeMirror-linenumber {
+  -moz-box-sizing: content-box;
+  box-sizing: content-box;
+}
+
+.CodeMirror-measure {
+  position: absolute;
+  width: 100%;
+  height: 0;
+  overflow: hidden;
+  visibility: hidden;
+}
+
+.CodeMirror-cursor {
+  position: absolute;
+  pointer-events: none;
+}
+.CodeMirror-measure pre {
+  position: static;
+}
+
+div.CodeMirror-cursors {
+  visibility: hidden;
+  position: relative;
+  z-index: 3;
+}
+div.CodeMirror-dragcursors {
+  visibility: visible;
+}
+
+.CodeMirror-focused div.CodeMirror-cursors {
+  visibility: visible;
+}
+
+.CodeMirror-selected {
+  background: #d9d9d9;
+}
+.CodeMirror-focused .CodeMirror-selected {
+  background: #d7d4f0;
+}
+.CodeMirror-crosshair {
+  cursor: crosshair;
+}
+.CodeMirror-line::selection,
+.CodeMirror-line > span::selection,
+.CodeMirror-line > span > span::selection {
+  background: #d7d4f0;
+}
+.CodeMirror-line::-moz-selection,
+.CodeMirror-line > span::-moz-selection,
+.CodeMirror-line > span > span::-moz-selection {
+  background: #d7d4f0;
+}
+
+.cm-searching {
+  background-color: #ffa;
+  background-color: rgba(255, 255, 0, 0.4);
+}
+
+/* Used to force a border model for a node */
+.cm-force-border {
+  padding-right: 0.1px;
+}
+
+@media print {
+  /* Hide the cursor when printing */
+  .CodeMirror div.CodeMirror-cursors {
+    visibility: hidden;
+  }
+}
+
+/* See issue #2901 */
+.cm-tab-wrap-hack:after {
+  content: "";
+}
+
+/* Help users use markselection to safely style text background */
+span.CodeMirror-selectedtext {
+  background: none;
+}

turing-machine/css/styles.css

@@ -1,5 +1,4 @@
 * {
-  font-family: "Trebuchet MS", sans-serif;
   margin: 0;
 }
 
@@ -7,7 +6,9 @@ button {
   background: #bbbbbb;
   border: 1px solid white;
   border-radius: 0.2rem;
-  padding: 0.2rem;
+  padding: 0.3rem;
+  display: inline-block;
+  cursor: pointer;
 }
 
 button:hover {
@@ -15,7 +16,7 @@ button:hover {
 }
 
 body {
-  margin: 0;
+  font-family: "Trebuchet MS", sans-serif;
   background-color: #aaaaaa;
 }
 
@@ -54,11 +55,12 @@ body {
   border-radius: 0.25rem;
   box-shadow: 2px 2px 5px #666666;
   background-color: #dddddd;
+  border: 2px solid white;
 
   position: relative;
   height: 80%;
-  transition: border 0.1s ease-in-out;
-  transition: background 0.1s ease-in-out;
+  transition: border 0.25s ease-in-out;
+  transition: background 0.25s ease-in-out;
 
   display: flex;
   flex-direction: column;
@@ -80,7 +82,7 @@ body {
   background-color: wheat;
   border-radius: 50%;
   opacity: 0.001;
-  transition: opacity 0.1s ease-in-out;
+  transition: opacity 0.25s ease-in-out;
 }
 
 .cell.reading .circle {
@@ -88,7 +90,7 @@ body {
 }
 
 .reading {
-  border-color: green;
+  border-color: wheat;
   background-color: wheat;
 }
 
@@ -105,6 +107,16 @@ body {
   font-size: 1rem;
 }
 
+.textarea-container {
+  display: flex;
+  flex-direction: column;
+  gap: 1rem;
+  box-shadow: 5px 5px 5px #666666;
+  border: 2px solid white;
+  border-radius: 0.25rem;
+  padding: 1rem;
+}
+
 textarea {
   border-radius: 0.25rem;
   height: 50vh;
@@ -119,11 +131,11 @@ textarea {
 }
 
 .controls {
-  display: flex;
+  display: none;
   gap: 1rem;
   flex-direction: row;
   justify-content: center;
-  align-items: center;
+  align-items: stretch;
 }
 
 hr {

turing-machine/index.html

@@ -1,29 +1,57 @@
 <!DOCTYPE html>
 <html>
-<head>
-  <title>Turing Machine Simulator</title>
-  <link rel="stylesheet" type="text/css" href="css/styles.css">
-</head>
-<body>
-  <div class="container">
-    <h1>Simponic's State System</h1>
-    <p>Author: Elizabeth Hunt</p>
-    <hr>
-    <p id="turing_state">State: _</p>
-    <div id="tape" class="tape"></div>
-    <div class="controls" id="controls" style="display: none">
-      <button id="next_step">Next Step</button> <button id=
-      "toggle_play">🔁 Begin</button> <button id=
-      "reset">Reset</button><br>
+  <head>
+    <title>Turing Machine Simulator</title>
+    <link rel="stylesheet" type="text/css" href="css/styles.css" />
+    <link rel="stylesheet" type="text/css" href="codemirror/codemirror.css" />
+  </head>
+  <body>
+    <div class="container">
+      <h1>Simponic's State System</h1>
+      <p><i>Developed for Kulyukin's CS5000</i></p>
+      <hr />
+      <p id="turing_state">State: _</p>
+      <div id="tape" class="tape"></div>
+      <div class="controls" id="controls">
+        <button id="toggle_play">🔁 Begin</button>
+        <button id="next_step">Next Step</button>
+        <button id="reset">Reset</button><br />
+      </div>
+      <div class="textarea-container">
+        <ul>
+          <li>
+            must have some instruction quadruple with the start state "q0"
+          </li>
+          <li>all computations will fail unless they end on the state "f"</li>
+          <li>
+            instructions are delimited with line breaks and are in the form
+            <i
+              >"< from_state > < read_symbol > < L/R/write_symbol > < to_state
+              >"</i
+            >
+          </li>
+          <li>comments ("//") are ignored</li>
+        </ul>
+        <textarea id="instructions">
+// replaces 3 B's with "1"
+q0 B 1 q1
+q1 1 R q1
+q1 B 1 q2
+q2 1 R q2
+q2 B 1 f</textarea
+        >
+        <div>
+          <button id="compile">Compile</button
+          ><span style="margin-left: 0.5rem" id="compile_status"></span>
+        </div>
+        <div>
+          <button id="copy_state">Copy State</button>
+        </div>
+      </div>
     </div>
-    <textarea id="instructions">test</textarea>
-    <div>
-      <button id="compile">Compile</button><span style=
-      "margin-left: 0.5rem" id="compile_status"></span>
-    </div>
-  </div>
-  <script src="js/observable.js"></script> 
-  <script src="js/turing_machine.js"></script> 
-  <script src="js/main.js"></script>
-</body>
+    <script src="codemirror/codemirror.js"></script>
+    <script src="js/observable.js"></script>
+    <script src="js/turing_machine.js"></script>
+    <script src="js/main.js"></script>
+  </body>
 </html>

turing-machine/js/main.js

@@ -1,3 +1,7 @@
+const TAPE_LEN = 150;
+const BLANK_VAL = "B";
+const SIMULATION_INTERVAL = 200;
+
 const MESSAGES = {
   SET_CELL: "SET_CELL",
   PAUSE: "PAUSE",
@@ -9,16 +13,13 @@ const MESSAGES = {
   NEW_TURING_STATE: "NEW_TURING_STATE",
 };
 
+// -- the "real" code
+
 const state = new Observable();
 
 const inputCellId = (cellId) => `${cellId}-input`;
 
-const setCellFromInput = (cellId, inputId) => {
-  const input = document.getElementById(inputId);
-  tape[cellId] = input.value;
-};
-
-const cell = (cellId, initValue = "NULL") => {
+const cell = (cellId, initValue = "B") => {
   const cellDiv = document.createElement("div");
   cellDiv.classList.add("cell");
   cellDiv.id = cellId;
@@ -38,7 +39,8 @@ const cell = (cellId, initValue = "NULL") => {
   input.addEventListener("focusout", () =>
     state.notify({ type: MESSAGES.SET_CELL, cell: cellId, value: input.value })
   );
-  state.subscribe((msg) => {
+
+  const msgListener = (msg) => {
     if (msg.type == MESSAGES.SET_CELL && msg.cell == cellId) {
       input.value = msg.value;
     }
@@ -50,7 +52,11 @@ const cell = (cellId, initValue = "NULL") => {
         });
       } else cellDiv.classList.remove("reading");
     }
-  });
+    if (msg.type == MESSAGES.COMPILE) {
+      state.unsubscribe(msgListener);
+    }
+  };
+  state.subscribe(msgListener);
 
   cellDiv.appendChild(input);
   cellDiv.appendChild(readingHead);
@@ -73,7 +79,7 @@ const parseRules = (rules, beginState) => {
       .map((x) => x.trim())
       .filter((x) => x);
     if (items.length != 4) {
-      throw new Error(`Invalid instruction on line ${line}`);
+      throw new Error(`Invalid instruction on line ${line + 1}`);
     }
     instructions.push(items);
   });
@@ -85,32 +91,58 @@ const parseRules = (rules, beginState) => {
   return instructions;
 };
 
-// --
+// -- a bit of some hacky ui code --
 
 const tapeEl = document.getElementById("tape");
 const compileButton = document.getElementById("compile");
-const instructionsEl = document.getElementById("instructions");
+const resetButton = document.getElementById("reset");
 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");
+const copyStateButton = document.getElementById("copy_state");
 
-resetButton.addEventListener("click", () => {
-  state.notify({ type: MESSAGES.PAUSE });
-  state.notify({ type: MESSAGES.COMPILE, value: instructionsEl.value });
+// init instructions from params
+const instructionsEl = document.getElementById("instructions");
+const editorEl = CodeMirror.fromTextArea(instructionsEl, {
+  lineNumbers: true,
 });
+const urlParams = new URLSearchParams(window.location.search);
+if (urlParams.get("instructions")) {
+  editorEl.setValue(atob(urlParams.get("instructions")));
+}
 
-compileButton.addEventListener("click", () => {
-  state.notify({ type: MESSAGES.COMPILE, value: instructionsEl.value });
-});
+[compileButton, resetButton].forEach((button) =>
+  button.addEventListener("click", () => {
+    state.notify({ type: MESSAGES.PAUSE });
+    state.notify({ type: MESSAGES.COMPILE, value: editorEl.getValue() });
+  })
+);
 
 nextStepButton.addEventListener("click", () => {
   state.notify({ type: MESSAGES.PAUSE });
   state.notify({ type: MESSAGES.NEXT_STEP });
 });
 
+// hackily copy the program state and put it in the clipboard
+copyStateButton.addEventListener("click", () => {
+  const start = Array(TAPE_LEN)
+    .fill(BLANK_VAL)
+    .map((blank, i) => document.getElementById(inputCellId(i))?.value ?? blank)
+    .join("")
+    .replaceAll(new RegExp(`(${BLANK_VAL})*\$`, "g"), "");
+  const instructions = btoa(editorEl.getValue());
+
+  navigator.clipboard
+    .writeText(
+      window.location.href.split("?")[0] +
+        `?start=${start}&instructions=${instructions}`
+    )
+    .then(() => alert("copied to clipboard"));
+});
+
+// simulate / pause button
 let playButton_simulationStatus = "paused";
 togglePlayButton.addEventListener("click", function () {
   if (playButton_simulationStatus == "paused") {
@@ -119,6 +151,16 @@ togglePlayButton.addEventListener("click", function () {
     state.notify({ type: MESSAGES.PAUSE });
   }
 });
+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.COMPILE_STATUS) {
@@ -142,22 +184,11 @@ state.subscribe((msg) => {
     if (error) {
       controlsEl.style.display = "none";
     } else if (success) {
-      controlsEl.style.display = "block";
+      controlsEl.style.display = "flex";
     }
   }
 });
 
-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;
@@ -167,35 +198,35 @@ state.subscribe((msg) => {
 // -
 
 const main = () => {
-  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);
-  }
-
   let turingMachine;
+  const startString = urlParams.get("start");
 
   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);
+        const beginState = "q0";
+        const acceptState = "f";
+        const tape = Array(TAPE_LEN)
+          .fill(BLANK_VAL)
+          .map((x, i) =>
+            startString && i < startString.length ? startString[i] : x
+          );
+
+        // put the cells into the tape
+        const cells = tape.map((_, cellId) => cell(cellId, tape[cellId]));
+        tapeEl.innerHTML = "";
+        for (const cell of cells) {
+          tapeEl.appendChild(cell);
+        }
+
+        const rules = parseRules(value, beginState, acceptState);
+        turingMachine = new TuringMachine(tape, rules, 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,
@@ -209,7 +240,7 @@ const main = () => {
     if (msg.type == MESSAGES.SIMULATE) {
       const interval = setInterval(() => {
         state.notify({ type: MESSAGES.NEXT_STEP });
-      }, 300);
+      }, SIMULATION_INTERVAL);
       const subscriptionFn = (msg) => {
         if (msg.type == MESSAGES.PAUSE) {
           clearInterval(interval);
@@ -231,7 +262,7 @@ const main = () => {
           type: MESSAGES.NEW_TURING_STATE,
           value: accepting
             ? `<span class='success'>Accept(${status})</span>`
-            : `<span class='error'>Fail(${status}}</span>`,
+            : `<span class='error'>Fail(${status})</span>`,
         });
       } else {
         state.notify({

turing-machine/js/turing_machine.js

@@ -1,16 +1,9 @@
 class TuringMachine {
-  constructor(
-    tape = [],
-    rules = [],
-    initialState = "q0",
-    blankSymbol = "B",
-    acceptState = "f"
-  ) {
+  constructor(tape = [], rules = [], initialState = "q0", 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;
@@ -51,7 +44,7 @@ class TuringMachine {
   }
 
   step() {
-    const currentSymbol = this.tape[this.head] || this.blankSymbol;
+    const currentSymbol = this.tape[this.head];
     const key = `${this.state},${currentSymbol}`;
     if (!(key in this.rules)) {
       return false;
@@ -60,6 +53,7 @@ class TuringMachine {
     const [newState, action] = rule.split(",");
 
     this.state = newState;
+    this.iteration++;
 
     if (action === "R") {
       this.head += 1;
@@ -73,10 +67,6 @@ class TuringMachine {
       return false;
     }
 
-    if (this.head >= 0 && this.head < this.tape.length) {
-      this.iteration++;
-      return true;
-    }
-    return false;
+    return this.head >= 0 && this.head < this.tape.length;
   }
 }