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Merge pull request #51 from tom-anders/fixHorde

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Fix insufficient material detection in Horde, add more test cases
This commit is contained in:
Vincent Velociter
2026-02-19 10:02:27 +00:00
committed by GitHub
parent c21c150755 e79a901409
commit 919f40f03a
5 changed files with 22111 additions and 65 deletions
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CHANGELOG.md
+7 -1
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@@ -1,6 +1,12 @@
## 0.12.1
- Fix a bug in `Horde.hasInsufficientMaterial` that would cause a stack overflow if only one pawn was left.
- Fix insufficient material detection when the Horde has a lone Queen.
- Horde positions where the king is white instead of black are now correctly considered invalid.
## 0.12.0
- Fix an en passant bug in crackyhouse and atomichess variants. Now the perft tests
- Fix an en passant bug in crazyhouse and atomicchess variants. Now the perft tests
cover these variants as well.
## 0.11.1
lib/src/board.dart
+4
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@@ -267,6 +267,7 @@ class Board {
.union(pawnAttacks(attacker.opposite, square).intersect(pawns)));
/// Puts a [Piece] on a [Square] overriding the existing one, if any.
@useResult
Board setPieceAt(Square square, Piece piece) {
return removePieceAt(square).copyWith(
occupied: occupied.withSquare(square),
@@ -283,6 +284,7 @@ class Board {
}
/// Removes the [Piece] at this [Square] if it exists.
@useResult
Board removePieceAt(Square square) {
final piece = pieceAt(square);
return piece != null
@@ -309,11 +311,13 @@ class Board {
}
/// Returns a new board with a new [promoted] square set.
@useResult
Board withPromoted(SquareSet promoted) {
return copyWith(promoted: promoted);
}
/// Returns a copy of this board with some fields updated.
@useResult
Board copyWith({
SquareSet? occupied,
SquareSet? promoted,
lib/src/position.dart
+43 -52
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@@ -1913,7 +1913,7 @@ abstract class Horde extends Position {
throw PositionSetupException.empty;
}
if (board.kings.size != 1) {
if (board.kings.size != 1 || board.kingOf(Side.black) == null) {
throw PositionSetupException.kings;
}
@@ -1934,27 +1934,19 @@ abstract class Horde extends Position {
}
}
// get the number of light or dark square bishops
int _hordeBishops(Side side, SquareColor sqColor) {
if (sqColor == SquareColor.light) {
return board
.piecesOf(side, Role.bishop)
.intersect(SquareSet.lightSquares)
.size;
}
// dark squares
return board
.piecesOf(side, Role.bishop)
.intersect(SquareSet.darkSquares)
.size;
}
/// get the number of light or dark square bishops of the [side]
int _numBishops(Side side, SquareColor sqColor) => board
.piecesOf(side, Role.bishop)
.intersect(sqColor == SquareColor.light
? SquareSet.lightSquares
: SquareSet.darkSquares)
.size;
SquareColor _hordeBishopColor(Side side) {
if (_hordeBishops(side, SquareColor.light) >= 1) {
return SquareColor.light;
}
return SquareColor.dark;
}
/// Number of light or dark square bishops of the horde (white)
int _hordeBishops(SquareColor color) => _numBishops(Side.white, color);
/// Number of light or dark square bishops of the pieces (black)
int _piecesBishops(SquareColor color) => _numBishops(Side.black, color);
bool _hasBishopPair(Side side) {
final bishops = board.piecesOf(side, Role.bishop);
@@ -1966,18 +1958,18 @@ abstract class Horde extends Position {
@override
bool hasInsufficientMaterial(Side side) {
// side with king can always win by capturing the horde
if (board.piecesOf(side, Role.king).isNotEmpty) {
// Black can always win by capturing the horde
if (side == Side.black) {
return false;
}
// now color represents horde and color.opposite is pieces
// now side represents horde (white) and side.opposite is pieces (black)
final hordeNum = board.piecesOf(side, Role.pawn).size +
board.piecesOf(side, Role.rook).size +
board.piecesOf(side, Role.queen).size +
board.piecesOf(side, Role.knight).size +
math.min(_hordeBishops(side, SquareColor.light), 2) +
math.min(_hordeBishops(side, SquareColor.dark), 2);
math.min(_hordeBishops(SquareColor.light), 2) +
math.min(_hordeBishops(SquareColor.dark), 2);
if (hordeNum == 0) {
return true;
@@ -1989,7 +1981,9 @@ abstract class Horde extends Position {
}
final hordeMap = board.materialCount(side);
final hordeBishopColor = _hordeBishopColor(side);
final hordeBishopColor = _hordeBishops(SquareColor.light) >= 1
? SquareColor.light
: SquareColor.dark;
final piecesMap = board.materialCount(side.opposite);
final piecesNum = board.bySide(side.opposite).size;
@@ -2010,9 +2004,7 @@ abstract class Horde extends Position {
return hordeNum == 2 &&
hordeMap[Role.rook]! == 1 &&
hordeMap[Role.bishop]! == 1 &&
(_pieceOfRoleNot(
piecesNum, _hordeBishops(side.opposite, hordeBishopColor)) ==
1);
(_pieceOfRoleNot(piecesNum, _piecesBishops(hordeBishopColor)) == 1);
}
if (hordeNum == 1) {
@@ -2030,18 +2022,19 @@ abstract class Horde extends Position {
return !(piecesMap[Role.pawn]! >= 1 ||
piecesMap[Role.rook]! >= 1 ||
_hordeBishops(side.opposite, SquareColor.light) >= 2 ||
_hordeBishops(side, SquareColor.dark) >= 2);
_piecesBishops(SquareColor.light) >= 2 ||
_piecesBishops(SquareColor.dark) >= 2);
} else if (hordeMap[Role.pawn] == 1) {
// Promote the pawn to a queen or a knight and check whether white can mate.
final pawnSquare = board.piecesOf(side, Role.pawn).last;
final promoteToQueen = copyWith();
promoteToQueen.board
.setPieceAt(pawnSquare!, Piece(color: side, role: Role.queen));
final promoteToKnight = copyWith();
promoteToKnight.board
.setPieceAt(pawnSquare, Piece(color: side, role: Role.knight));
final promoteToQueen = copyWith(
board: board.setPieceAt(
pawnSquare!, Piece(color: side, role: Role.queen)));
final promoteToKnight = copyWith(
board: board.setPieceAt(
pawnSquare, Piece(color: side, role: Role.knight)));
return promoteToQueen.hasInsufficientMaterial(side) &&
promoteToKnight.hasInsufficientMaterial(side);
} else if (hordeMap[Role.rook] == 1) {
@@ -2068,8 +2061,8 @@ abstract class Horde extends Position {
// a pawn/opposite-color-bishop on A4, a pawn/opposite-color-bishop on
// B3, a pawn/bishop/rook/queen on A2 and any other piece on B2.
return !(_hordeBishops(side.opposite, hordeBishopColor.opposite) >= 2 ||
(_hordeBishops(side.opposite, hordeBishopColor.opposite) >= 1 &&
return !(_piecesBishops(hordeBishopColor.opposite) >= 2 ||
(_piecesBishops(hordeBishopColor.opposite) >= 1 &&
piecesMap[Role.pawn]! >= 1) ||
piecesMap[Role.pawn]! >= 2);
} else if (hordeMap[Role.knight] == 1) {
@@ -2092,13 +2085,12 @@ abstract class Horde extends Position {
(piecesMap[Role.bishop]! >= 1 && piecesMap[Role.pawn]! >= 1) ||
(_hasBishopPair(side.opposite) &&
piecesMap[Role.pawn]! >= 1)) &&
(_hordeBishops(side.opposite, SquareColor.light) < 2 ||
(_pieceOfRoleNot(piecesNum,
_hordeBishops(side.opposite, SquareColor.light)) >=
(_piecesBishops(SquareColor.light) < 2 ||
(_pieceOfRoleNot(
piecesNum, _piecesBishops(SquareColor.light)) >=
3)) &&
(_hordeBishops(side.opposite, SquareColor.dark) < 2 ||
(_pieceOfRoleNot(piecesNum,
_hordeBishops(side.opposite, SquareColor.dark)) >=
(_piecesBishops(SquareColor.dark) < 2 ||
(_pieceOfRoleNot(piecesNum, _piecesBishops(SquareColor.dark)) >=
3)));
}
} else if (hordeNum == 2) {
@@ -2122,9 +2114,8 @@ abstract class Horde extends Position {
} else if (hordeMap[Role.bishop]! >= 1 && hordeMap[Role.knight]! >= 1) {
// horde has a bishop and a knight
return !(piecesMap[Role.pawn]! >= 1 ||
_hordeBishops(side.opposite, hordeBishopColor.opposite) >= 1 ||
(_pieceOfRoleNot(piecesNum,
_hordeBishops(side.opposite, hordeBishopColor)) >=
_piecesBishops(hordeBishopColor.opposite) >= 1 ||
(_pieceOfRoleNot(piecesNum, _piecesBishops(hordeBishopColor)) >=
3));
} else {
// The horde has two or more bishops on the same color.
@@ -2138,11 +2129,11 @@ abstract class Horde extends Position {
// have a pawn and an opposite color bishop.
return !((piecesMap[Role.pawn]! >= 1 &&
_hordeBishops(side.opposite, hordeBishopColor.opposite) >= 1) ||
_piecesBishops(hordeBishopColor.opposite) >= 1) ||
(piecesMap[Role.pawn]! >= 1 && piecesMap[Role.knight]! >= 1) ||
(_hordeBishops(side.opposite, hordeBishopColor.opposite) >= 1 &&
(_piecesBishops(hordeBishopColor.opposite) >= 1 &&
piecesMap[Role.knight]! >= 1) ||
(_hordeBishops(side.opposite, hordeBishopColor.opposite) >= 2) ||
(_piecesBishops(hordeBishopColor.opposite) >= 2) ||
piecesMap[Role.knight]! >= 2 ||
piecesMap[Role.pawn]! >= 2);
}
test/position_test.dart
+61 -12
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@@ -1,6 +1,7 @@
import 'package:fast_immutable_collections/fast_immutable_collections.dart';
import 'package:dartchess/dartchess.dart';
import 'package:test/test.dart';
import 'dart:io' as io;
void main() {
group('Position', () {
@@ -1116,19 +1117,67 @@ void main() {
});
group('Horde', () {
test('insufficient material', () {
for (final test in [
['8/5k2/8/8/8/4NN2/8/8 w - - 0 1', true, false],
['8/8/8/2B5/p7/kp6/pq6/8 b - - 0 1', false, false],
['8/8/8/2B5/r7/kn6/nr6/8 b - - 0 1', true, false],
['8/8/1N6/rb6/kr6/qn6/8/8 b - - 0 1', false, false],
['8/8/1N6/qq6/kq6/nq6/8/8 b - - 0 1', true, false],
['8/P1P5/8/8/8/8/brqqn3/k7 b - - 0 1', false, false],
]) {
final pos = Horde.fromSetup(Setup.parseFen(test[0] as String));
expect(pos.hasInsufficientMaterial(Side.white), test[1]);
expect(pos.hasInsufficientMaterial(Side.black), test[2]);
group('insufficient material', () {
for (final line
in io.File('test/resources/horde_insufficient_material.csv')
.readAsLinesSync()) {
final [fen, expected, tag] = line.split(',');
test('[$tag] $fen', () {
final pos = Horde.fromSetup(Setup.parseFen(fen));
expect(pos.hasInsufficientMaterial(Side.white), expected == 'true');
expect(pos.hasInsufficientMaterial(Side.black), false);
});
}
});
group('Position validation', () {
test('Empty board', () {
expect(
() => Horde.fromSetup(Setup.parseFen(kEmptyFEN)),
throwsA(predicate((e) =>
e is PositionSetupException &&
e.cause == IllegalSetupCause.empty)));
});
test('Missing kings', () {
expect(
() => Horde.fromSetup(Setup.parseFen(
'rnbq1bnr/pppppppp/8/1PP2PP1/PPPPPPPP/PPPPPPPP/PPPPPPPP/PPPPPPPP w - - 0 1')),
throwsA(predicate((e) =>
e is PositionSetupException &&
e.cause == IllegalSetupCause.kings)));
});
test('King is white', () {
expect(
() => Horde.fromSetup(Setup.parseFen(
'rnbq1bnr/pppppppp/8/1PPK1PP1/PPPPPPPP/PPPPPPPP/PPPPPPPP/PPPPPPPP w - - 0 1')),
throwsA(predicate((e) =>
e is PositionSetupException &&
e.cause == IllegalSetupCause.kings)));
});
test('Both sides have a king', () {
expect(
() => Horde.fromSetup(Setup.parseFen(
'rnbqkbnr/pppppppp/8/1PPK1PP1/PPPPPPPP/PPPPPPPP/PPPPPPPP/PPPPPPPP w kq - 0 1')),
throwsA(predicate((e) =>
e is PositionSetupException &&
e.cause == IllegalSetupCause.kings)));
});
test('Opposite check', () {
expect(
() => Horde.fromSetup(
Setup.parseFen('3k4/8/1B6/8/8/8/8/8 w - - 0 1')),
throwsA(predicate((e) =>
e is PositionSetupException &&
e.cause == IllegalSetupCause.oppositeCheck)));
});
test('Backrank pawns (black)', () {
expect(
() => Horde.fromSetup(
Setup.parseFen('2k3p1/8/8/8/8/3P4/8/8 w - - 0 1')),
throwsA(predicate((e) =>
e is PositionSetupException &&
e.cause == IllegalSetupCause.pawnsOnBackrank)));
});
});
});
}
test/resources/horde_insufficient_material.csv
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