shogi 0.0.3

A simple shogi engine for Dart and Flutter. This engine can be combined with `flutter_shogi_board` to render static game board positions, tsume problems or shogi castles.

shogi

A simple shogi engine for Dart and Flutter. This engine can be combined with flutter_shogi_board to render static game board positions, tsume problems or shogi castles.

Shogi (将棋) is a two-player strategy board game native to Japan, belonging to the same family as chess and xiangqi.

Presently the package is very basic in which it can determine the static board position for a given game and move pieces from one position to another. As it is still highly experimental, 0.0.x versioning is used.

Getting Started

Import the package

To import this package, simply add shogi as a dependency in pubspec.yaml

dependencies:
  flutter:
    sdk: flutter
  shogi:

Note that this package requires dart >= 2.6.0.

Example

import 'package:shogi/shogi.dart';

void main() {
  final gameBoard = ShogiUtils.initialBoard;
  gameBoard.printToConsole();
}

Importing a Game Board

SFEN

A game board can be imported using a SFEN ascii string:

final sfenString = 'lnsgkgsnl/1r5b1/ppppppppp/9/9/9/PPPPPPPPP/1B5R1/LNSGKGSNL b -';
final gameBoard = ShogiUtils.sfenStringToGameBoard(sfenString);
gameBoard.printToConsole();

|l |n |s |g |k |g |s |n |l |
|  |r |  |  |  |  |  |b |  |
|p |p |p |p |p |p |p |p |p |
|  |  |  |  |  |  |  |  |  |
|  |  |  |  |  |  |  |  |  |
|  |  |  |  |  |  |  |  |  |
|P |P |P |P |P |P |P |P |P |
|  |B |  |  |  |  |  |R |  |
|L |N |S |G |K |G |S |N |L |

Custom Notation

A board position is notated using {PieceType}-{Row}{Column}, i.e. K-59. Note that 11 is the top right board cell as per japanese notation.

final yagura = ['L-99', 'N-89', 'K-88', 'G-78', 'P-97', 'P-87', 'S-77', 'G-67', 'P-76', 'P-66', 'P-56'];
final gameBoard = ShogiUtils.stringArrayToGameBoard(yagura);

If Sente or Gote aren't specified, then Sente is chosen by default. To import pieces for both players, use the notation {Player}:{PieceType}-{Row}{Column}, where ☗ and ☖ denote Sente and Gote respectively.

final tsume1 = ['☖:K-51', '☖:S-61', '☖:S-41', '☗:+P-53', '☗:+B-25'];

If a position isn't given, then the piece is inferred as being in hand for that player: {PieceType} for sente or {Player}:{PieceType} to choose specific player.

Piece Movement

Piece movement is denoted by {Player}{PieceType}{CurrentPosition}{Movement}{TargetPosition}{Promotion}.

{Promotion} is optional, while if {Player} isn't specified, Sente is chosen by default. {CurrentPosition} is needed for all movement types, except drops. Movement is denoted by -, x and *, that is, simple movement, capture and drop respectfully. Some examples:

Type	Example	Explanation
Simple movement	☗P77-76	Sente's pawn moves from 77 to 76.
Capture	☗P75x74	Sente's pawn moves from 77 to 74 and captures the piece at 74.
Drop	☗S*34	Sente's drops a silver from in hand onto 34.
Combined	☗S34x33+	Sente's silver moves from 34 to 33, captures the piece at 33 and is promoted.

Thus, given an initial board for Sente, a Yagura castle could be build using the following moves:

1: ☗P77-76
2: ☗S79-68
3: ☗S68-77
4: ☗G69-78
5: ☗P57-56
6: ☗K59-69
7: ☗G49-58
8: ☗B88-79
9: ☗P67-66
10: ☗G58-67
11: ☗B79-68
12: ☗K69-79
13: ☗K79-88

Future Plans

The packages shogi and flutter_shogi_board grew out of my desired to visualize shogi castles in Flutter, and with no game board widget or even a shogi engine available, I decided to roll my own.

In the future I would like to utilize these packages not just for displaying static game boards, but also for tsume problems, thus user interaction may be considered.

The notation ☗P77-76 is currently utilized to denote moves, however KIF may be more suitable for future versions:

1 ７六歩(77)
2 ３四歩(33)
3 ７五歩(76)

Raising Issues and Contributing

Please report bugs and issues, and raise feature requests on GitHub.

To contribute, submit a PR with a detailed description and tests, if applicable.