Modify moves encoding to handle resignation

docs-src/examples/preset-moves.md

@@ -45,6 +45,8 @@ Since hexagonal chess has no castling, we do not need to deal with that notation
 
 Lastly, promotion is handled with the `=` sign. So a white pawn that moved from `A5` to `A6` and became a Rook would be written as `A5-A6=R`.
 
+If a player resigns instead of being checkmated, append `,R` to the end of the moves list. The alternating turn order already encodes which player resigned, so the marker only needs to appear once at the end.
+
 ```html
 <div style="width: 575px; height: 500px">
   <hexchess-board

docs/examples/change-look/index.html

@@ -39,27 +39,27 @@ <h1>Example: Customizing colors</h1>
                   </li>
 
                   <li class=>
-                    <a href="../custom-pieces/">Override the built-in set with slots</a>
+                    <a href="../darkmode/">Dark and light modes are both supported.</a>
                   </li>
 
                   <li class=>
-                    <a href="../darkmode/">Dark and light modes are both supported.</a>
+                    <a href="../">Common keyboard operations</a>
                   </li>
 
                   <li class=>
-                    <a href="../hexfen/">Customizing the board layout with Hex-FEN</a>
+                    <a href="../player-roles/">Set player roles</a>
                   </li>
 
                   <li class=>
-                    <a href="../">Common keyboard operations</a>
+                    <a href="../preset-moves/">Analyzing a game that has a specific set of moves played.</a>
                   </li>
 
                   <li class=>
-                    <a href="../player-roles/">Set player roles</a>
+                    <a href="../custom-pieces/">Override the built-in set with slots</a>
                   </li>
 
                   <li class=>
-                    <a href="../preset-moves/">Analyzing a game that has a specific set of moves played.</a>
+                    <a href="../hexfen/">Customizing the board layout with Hex-FEN</a>
                   </li>
 
         </ul>

docs/examples/custom-pieces/index.html

@@ -38,18 +38,10 @@ <h1>Example: Custom pieces</h1>
                     <a href="../change-look/">Changing the look and feel of the board</a>
                   </li>
 
-                  <li class=selected>
-                    <a href="">Override the built-in set with slots</a>
-                  </li>
-
                   <li class=>
                     <a href="../darkmode/">Dark and light modes are both supported.</a>
                   </li>
 
-                  <li class=>
-                    <a href="../hexfen/">Customizing the board layout with Hex-FEN</a>
-                  </li>
-
                   <li class=>
                     <a href="../">Common keyboard operations</a>
                   </li>
@@ -62,6 +54,14 @@ <h1>Example: Custom pieces</h1>
                     <a href="../preset-moves/">Analyzing a game that has a specific set of moves played.</a>
                   </li>
 
+                  <li class=selected>
+                    <a href="">Override the built-in set with slots</a>
+                  </li>
+
+                  <li class=>
+                    <a href="../hexfen/">Customizing the board layout with Hex-FEN</a>
+                  </li>
+
         </ul>
       </nav>
       <div>

docs/examples/darkmode/index.html

@@ -38,18 +38,10 @@ <h1>Example: Dark Mode</h1>
                     <a href="../change-look/">Changing the look and feel of the board</a>
                   </li>
 
-                  <li class=>
-                    <a href="../custom-pieces/">Override the built-in set with slots</a>
-                  </li>
-
                   <li class=selected>
                     <a href="">Dark and light modes are both supported.</a>
                   </li>
 
-                  <li class=>
-                    <a href="../hexfen/">Customizing the board layout with Hex-FEN</a>
-                  </li>
-
                   <li class=>
                     <a href="../">Common keyboard operations</a>
                   </li>
@@ -62,6 +54,14 @@ <h1>Example: Dark Mode</h1>
                     <a href="../preset-moves/">Analyzing a game that has a specific set of moves played.</a>
                   </li>
 
+                  <li class=>
+                    <a href="../custom-pieces/">Override the built-in set with slots</a>
+                  </li>
+
+                  <li class=>
+                    <a href="../hexfen/">Customizing the board layout with Hex-FEN</a>
+                  </li>
+
         </ul>
       </nav>
       <div>

docs/examples/hexfen/index.html

@@ -38,18 +38,10 @@ <h1>Example: Hex-FEN Notation</h1>
                     <a href="../change-look/">Changing the look and feel of the board</a>
                   </li>
 
-                  <li class=>
-                    <a href="../custom-pieces/">Override the built-in set with slots</a>
-                  </li>
-
                   <li class=>
                     <a href="../darkmode/">Dark and light modes are both supported.</a>
                   </li>
 
-                  <li class=selected>
-                    <a href="">Customizing the board layout with Hex-FEN</a>
-                  </li>
-
                   <li class=>
                     <a href="../">Common keyboard operations</a>
                   </li>
@@ -62,6 +54,14 @@ <h1>Example: Hex-FEN Notation</h1>
                     <a href="../preset-moves/">Analyzing a game that has a specific set of moves played.</a>
                   </li>
 
+                  <li class=>
+                    <a href="../custom-pieces/">Override the built-in set with slots</a>
+                  </li>
+
+                  <li class=selected>
+                    <a href="">Customizing the board layout with Hex-FEN</a>
+                  </li>
+
         </ul>
       </nav>
       <div>

docs/examples/index.html

@@ -38,18 +38,10 @@ <h1>Example: Keyboard input</h1>
                     <a href="change-look/">Changing the look and feel of the board</a>
                   </li>
 
-                  <li class=>
-                    <a href="custom-pieces/">Override the built-in set with slots</a>
-                  </li>
-
                   <li class=>
                     <a href="darkmode/">Dark and light modes are both supported.</a>
                   </li>
 
-                  <li class=>
-                    <a href="hexfen/">Customizing the board layout with Hex-FEN</a>
-                  </li>
-
                   <li class=selected>
                     <a href="">Common keyboard operations</a>
                   </li>
@@ -62,6 +54,14 @@ <h1>Example: Keyboard input</h1>
                     <a href="preset-moves/">Analyzing a game that has a specific set of moves played.</a>
                   </li>
 
+                  <li class=>
+                    <a href="custom-pieces/">Override the built-in set with slots</a>
+                  </li>
+
+                  <li class=>
+                    <a href="hexfen/">Customizing the board layout with Hex-FEN</a>
+                  </li>
+
         </ul>
       </nav>
       <div>

docs/examples/preset-moves/index.html

@@ -38,18 +38,10 @@ <h1>Example: Preset Moves</h1>
                     <a href="../change-look/">Changing the look and feel of the board</a>
                   </li>
 
-                  <li class=>
-                    <a href="../custom-pieces/">Override the built-in set with slots</a>
-                  </li>
-
                   <li class=>
                     <a href="../darkmode/">Dark and light modes are both supported.</a>
                   </li>
 
-                  <li class=>
-                    <a href="../hexfen/">Customizing the board layout with Hex-FEN</a>
-                  </li>
-
                   <li class=>
                     <a href="../">Common keyboard operations</a>
                   </li>
@@ -62,6 +54,14 @@ <h1>Example: Preset Moves</h1>
                     <a href="">Analyzing a game that has a specific set of moves played.</a>
                   </li>
 
+                  <li class=>
+                    <a href="../custom-pieces/">Override the built-in set with slots</a>
+                  </li>
+
+                  <li class=>
+                    <a href="../hexfen/">Customizing the board layout with Hex-FEN</a>
+                  </li>
+
         </ul>
       </nav>
       <div>
@@ -96,6 +96,7 @@ <h1>Example: Preset Moves</h1>
 <p>En passant captures are notated with an <code>$</code> at the end. This is done to simplify the format of notations into a standard of a square, followed by <code>x</code> or <code>-</code>, followed by a square, and then either <code>$</code> or <code>=</code>.</p>
 <p>Since hexagonal chess has no castling, we do not need to deal with that notation.</p>
 <p>Lastly, promotion is handled with the <code>=</code> sign. So a white pawn that moved from <code>A5</code> to <code>A6</code> and became a Rook would be written as <code>A5-A6=R</code>.</p>
+<p>If a player resigns instead of being checkmated, append <code>,R</code> to the end of the moves list. The alternating turn order already encodes which player resigned, so the marker only needs to appear once at the end.</p>
 <pre class="language-html"><code class="language-html"><span class="token tag"><span class="token tag"><span class="token punctuation">&lt;</span>div</span> <span class="token special-attr"><span class="token attr-name">style</span><span class="token attr-value"><span class="token punctuation attr-equals">=</span><span class="token punctuation">"</span><span class="token value css language-css"><span class="token property">width</span><span class="token punctuation">:</span> 575px<span class="token punctuation">;</span> <span class="token property">height</span><span class="token punctuation">:</span> 500px</span><span class="token punctuation">"</span></span></span><span class="token punctuation">></span></span><br>  <span class="token tag"><span class="token tag"><span class="token punctuation">&lt;</span>hexchess-board</span><br>    <span class="token attr-name">id</span><span class="token attr-value"><span class="token punctuation attr-equals">=</span><span class="token punctuation">"</span>hexchess-board<span class="token punctuation">"</span></span><br>    <span class="token attr-name">board</span><span class="token attr-value"><span class="token punctuation attr-equals">=</span><span class="token punctuation">"</span>start<span class="token punctuation">"</span></span><br>    <span class="token attr-name">orientation</span><span class="token attr-value"><span class="token punctuation attr-equals">=</span><span class="token punctuation">"</span>white<span class="token punctuation">"</span></span><br>    <span class="token attr-name">moves</span><span class="token attr-value"><span class="token punctuation attr-equals">=</span><span class="token punctuation">"</span>B1-B3,B7-B5,C2-C4,D7-D5,C4xD5p,F11xB3P,C1xC7p<span class="token punctuation">"</span></span><br>  <span class="token punctuation">></span></span><span class="token tag"><span class="token tag"><span class="token punctuation">&lt;/</span>hexchess-board</span><span class="token punctuation">></span></span><br><span class="token tag"><span class="token tag"><span class="token punctuation">&lt;/</span>div</span><span class="token punctuation">></span></span></code></pre>
 <div style="width: 575px; height: 500px">
   <hexchess-board

src/test/utils.test.ts

@@ -32,7 +32,70 @@ describe('Utils', () => {
         promotion: 'N',
       },
     ];
-    expect(movesToString(moves)).toBe('A1-A2,B2-B1=q,C2-C4,D4xC3P$,B6xA6r=N');
+    const encoded = 'A1-A2,B2-B1=q,C2-C4,D4xC3P$,B6xA6r=N';
+    expect(movesToString(moves)).toBe(encoded);
+    expect(movesToString(moves, true)).toBe(`${encoded},R`);
+  });
+
+  test('Move strings round-trip without losing information', () => {
+    const moves: Move[] = [
+      { from: 'B1', to: 'B3', enPassant: false, promotion: null },
+      { from: 'C7', to: 'C5', enPassant: false, promotion: null },
+      { from: 'B3', to: 'B4', enPassant: false, promotion: null },
+      {
+        from: 'C5',
+        to: 'B4',
+        capturedPiece: 'P',
+        enPassant: false,
+        promotion: null,
+      },
+      { from: 'D3', to: 'D5', enPassant: false, promotion: null },
+      { from: 'E7', to: 'E5', enPassant: false, promotion: null },
+      {
+        from: 'D5',
+        to: 'E6',
+        capturedPiece: 'p',
+        enPassant: true,
+        promotion: null,
+      },
+      { from: 'B4', to: 'B3', enPassant: false, promotion: null },
+      {
+        from: 'E6',
+        to: 'F7',
+        capturedPiece: 'p',
+        enPassant: false,
+        promotion: null,
+      },
+      { from: 'B3', to: 'B2', enPassant: false, promotion: null },
+      {
+        from: 'F7',
+        to: 'G7',
+        capturedPiece: 'p',
+        enPassant: false,
+        promotion: null,
+      },
+      { from: 'B2', to: 'B1', enPassant: false, promotion: 'q' },
+    ];
+
+    const encoded = movesToString(moves);
+    expect(stringToMoves(encoded)).toEqual(moves);
+  });
+
+  test('Move strings round-trip when resignation is included', () => {
+    const moves: Move[] = [
+      { from: 'A1', to: 'A2', enPassant: false, promotion: null },
+      {
+        from: 'B2',
+        to: 'A3',
+        capturedPiece: 'n',
+        enPassant: false,
+        promotion: null,
+      },
+    ];
+
+    const encoded = movesToString(moves, true);
+    expect(encoded.endsWith(',R')).toBe(true);
+    expect(stringToMoves(encoded)).toEqual(moves);
   });
 
   test('Converts a CSV string to moves properly', () => {
@@ -79,6 +142,55 @@ describe('Utils', () => {
     expect(stringToMoves(moveStr)).toEqual(moves);
   });
 
+  test('stringToMoves handles a resignation marker', () => {
+    const base =
+      'B1-B3,C7-C5,B3-B4,C5xB4P,D3-D5,E7-E5,D5xE6p$,B4-B3,E6xF7p,B3-B2,F7xG7p,B2-B1=q';
+    const expected: Move[] = [
+      { from: 'B1', to: 'B3', enPassant: false, promotion: null },
+      { from: 'C7', to: 'C5', enPassant: false, promotion: null },
+      { from: 'B3', to: 'B4', enPassant: false, promotion: null },
+      {
+        from: 'C5',
+        to: 'B4',
+        capturedPiece: 'P',
+        enPassant: false,
+        promotion: null,
+      },
+      { from: 'D3', to: 'D5', enPassant: false, promotion: null },
+      { from: 'E7', to: 'E5', enPassant: false, promotion: null },
+      {
+        from: 'D5',
+        to: 'E6',
+        capturedPiece: 'p',
+        enPassant: true,
+        promotion: null,
+      },
+      { from: 'B4', to: 'B3', enPassant: false, promotion: null },
+      {
+        from: 'E6',
+        to: 'F7',
+        capturedPiece: 'p',
+        enPassant: false,
+        promotion: null,
+      },
+      { from: 'B3', to: 'B2', enPassant: false, promotion: null },
+      {
+        from: 'F7',
+        to: 'G7',
+        capturedPiece: 'p',
+        enPassant: false,
+        promotion: null,
+      },
+      { from: 'B2', to: 'B1', enPassant: false, promotion: 'q' },
+    ];
+
+    expect(stringToMoves(`${base},R`)).toEqual(expected);
+    expect(stringToMoves('R')).toEqual([]);
+    expect(() => stringToMoves('R,B1-B3')).toThrow(
+      'Cannot process resignation when subsequent moves still exist.',
+    );
+  });
+
   test('fenToBoard falls back to an empty board for invalid input', () => {
     expect(fenToBoard('invalid').numPieces()).toBe(0);
     expect(fenToBoard(null).numPieces()).toBe(0);

src/utils.ts

@@ -1,6 +1,8 @@
 import { Board } from './board';
 import type { Color, Move, Piece } from './types';
 
+export const RESIGNATION_MARKER = 'R';
+
 export const COLUMN_ARRAY = [
   'A',
   'B',
@@ -188,7 +190,7 @@ export const fenToBoard = (position: string | null): Board => {
   return converted;
 };
 
-export const movesToString = (moves: Move[]): string => {
+export const movesToString = (moves: Move[], resigned = false): string => {
   const result: string[] = [];
   for (const move of moves) {
     let newString = move.capturedPiece
@@ -202,6 +204,9 @@ export const movesToString = (moves: Move[]): string => {
     }
     result.push(newString);
   }
+  if (resigned) {
+    result.push(RESIGNATION_MARKER);
+  }
   return result.join(',');
 };
 
@@ -214,7 +219,16 @@ export const stringToMoves = (movesStr: string): Move[] => {
 
   const moves = movesStr.split(',');
   const result: Move[] = [];
-  for (const move of moves) {
+  for (let i = 0; i < moves.length; i++) {
+    const move = moves[i];
+    if (move === RESIGNATION_MARKER) {
+      if (i !== moves.length - 1) {
+        throw new Error(
+          'Cannot process resignation when subsequent moves still exist.',
+        );
+      }
+      break;
+    }
     if (!moveRegex.test(move)) {
       throw new Error(`Invalid move: ${move}`);
     }