The library that implements checking and generating of chess moves.
Disclaimer: this library was written directly on an Android smartphone with the AnGoIde IDE.
- representing the board:
- as an associative array of pieces with their positions as keys;
- as a plain array of pieces with exact correspondence array indices to piece positions;
- as a set of integers corresponding to a particular combination of piece color and type, and where each bit corresponds to a particular piece position (so-called a bitboard);
- immutable applicating moves to the board via copying the latter;
- checkings of moves:
- universal;
- individual for all types of pieces;
- generating moves via filtering from all possible ones;
- move restrictions (abandoned moves):
- pawn double-move;
- en passant capture;
- promotion;
- castling;
- perft function;
- using an abstraction of a piece;
- Forsyth-Edwards Notation:
- parsing:
- of a position;
- of a move;
- of a piece kind;
- of a piece color;
- of a board;
- serialization:
- of a position;
- of a move;
- of a piece kind;
- of a piece color;
- of a board;
- parsing:
- utilities:
- utility for counting all possible moves (based on the perft function);
- utility for generating all possible chess moves;
- utility for comparing the generation of all possible chess moves by different board representations.
$ go get github.com/thewizardplusplus/go-chess-models
boards.MapBoard.CheckMove():
package main
import (
"fmt"
"github.com/thewizardplusplus/go-chess-models/boards"
"github.com/thewizardplusplus/go-chess-models/common"
"github.com/thewizardplusplus/go-chess-models/pieces"
)
func main() {
board := boards.NewMapBoard(common.Size{Width: 5, Height: 5}, []common.Piece{
pieces.NewRook(common.Black, common.Position{File: 2, Rank: 2}),
pieces.NewBishop(common.White, common.Position{File: 3, Rank: 3}),
})
moveOne := common.Move{
Start: common.Position{File: 2, Rank: 2},
Finish: common.Position{File: 3, Rank: 3},
}
fmt.Printf("%+v: %v\n", moveOne, board.CheckMove(moveOne))
moveTwo := common.Move{
Start: common.Position{File: 3, Rank: 3},
Finish: common.Position{File: 2, Rank: 2},
}
fmt.Printf("%+v: %v\n", moveTwo, board.CheckMove(moveTwo))
// Output:
// {Start:{File:2 Rank:2} Finish:{File:3 Rank:3}}: illegal move
// {Start:{File:3 Rank:3} Finish:{File:2 Rank:2}}: <nil>
}boards.MapBoard.ApplyMove():
package main
import (
"fmt"
"sort"
"github.com/thewizardplusplus/go-chess-models/boards"
"github.com/thewizardplusplus/go-chess-models/common"
"github.com/thewizardplusplus/go-chess-models/pieces"
)
type ByPosition []common.Piece
func (group ByPosition) Len() int {
return len(group)
}
func (group ByPosition) Swap(i int, j int) {
group[i], group[j] = group[j], group[i]
}
func (group ByPosition) Less(i int, j int) bool {
a, b := group[i].Position(), group[j].Position()
if a.File == b.File {
return a.Rank < b.Rank
}
return a.File < b.File
}
func main() {
board := boards.NewMapBoard(common.Size{Width: 5, Height: 5}, []common.Piece{
pieces.NewRook(common.Black, common.Position{File: 2, Rank: 2}),
pieces.NewBishop(common.White, common.Position{File: 3, Rank: 3}),
})
pieces := board.Pieces()
sort.Sort(ByPosition(pieces))
fmt.Printf("%+v\n", pieces)
updatedBoard := board.ApplyMove(common.Move{
Start: common.Position{File: 3, Rank: 3},
Finish: common.Position{File: 2, Rank: 2},
})
updatedPieces := updatedBoard.Pieces()
sort.Sort(ByPosition(updatedPieces))
fmt.Printf("%+v\n", updatedPieces)
// Output:
// [{Base:{kind:2 color:0 position:{File:2 Rank:2}}} {Base:{kind:3 color:1 position:{File:3 Rank:3}}}]
// [{Base:{kind:3 color:1 position:{File:2 Rank:2}}}]
}chessmodels.MoveGenerator.MovesForColor():
package main
import (
"fmt"
"sort"
models "github.com/thewizardplusplus/go-chess-models"
"github.com/thewizardplusplus/go-chess-models/boards"
"github.com/thewizardplusplus/go-chess-models/common"
"github.com/thewizardplusplus/go-chess-models/pieces"
)
func main() {
board := boards.NewMapBoard(common.Size{Width: 5, Height: 5}, []common.Piece{
pieces.NewRook(common.Black, common.Position{File: 2, Rank: 2}),
pieces.NewKnight(common.White, common.Position{File: 3, Rank: 3}),
pieces.NewPawn(common.White, common.Position{File: 4, Rank: 3}),
})
var generator models.MoveGenerator
moves, _ := generator.MovesForColor(board, common.White)
// sorting only by the final point will be sufficient for the reproducibility
// of this example
sort.Slice(moves, func(i int, j int) bool {
a, b := moves[i].Finish, moves[j].Finish
if a.File == b.File {
return a.Rank < b.Rank
}
return a.File < b.File
})
for _, move := range moves {
fmt.Printf("%+v\n", move)
}
// Output:
// {Start:{File:3 Rank:3} Finish:{File:1 Rank:2}}
// {Start:{File:3 Rank:3} Finish:{File:1 Rank:4}}
// {Start:{File:3 Rank:3} Finish:{File:2 Rank:1}}
// {Start:{File:3 Rank:3} Finish:{File:4 Rank:1}}
// {Start:{File:4 Rank:3} Finish:{File:4 Rank:4}}
}uci.DecodeMove():
package main
import (
"fmt"
"github.com/thewizardplusplus/go-chess-models/encoding/uci"
)
func main() {
move, _ := uci.DecodeMove("d4c3")
fmt.Printf("%+v\n", move)
// Output: {Start:{File:3 Rank:3} Finish:{File:2 Rank:2}}
}uci.EncodeMove():
package main
import (
"fmt"
"github.com/thewizardplusplus/go-chess-models/common"
"github.com/thewizardplusplus/go-chess-models/encoding/uci"
)
func main() {
move := uci.EncodeMove(common.Move{
Start: common.Position{File: 3, Rank: 3},
Finish: common.Position{File: 2, Rank: 2},
})
fmt.Printf("%v\n", move)
// Output: d4c3
}uci.DecodePieceStorage():
package main
import (
"fmt"
"sort"
"github.com/thewizardplusplus/go-chess-models/boards"
"github.com/thewizardplusplus/go-chess-models/common"
"github.com/thewizardplusplus/go-chess-models/encoding/uci"
"github.com/thewizardplusplus/go-chess-models/pieces"
)
type ByPosition []common.Piece
func (group ByPosition) Len() int {
return len(group)
}
func (group ByPosition) Swap(i int, j int) {
group[i], group[j] = group[j], group[i]
}
func (group ByPosition) Less(i int, j int) bool {
a, b := group[i].Position(), group[j].Position()
if a.File == b.File {
return a.Rank < b.Rank
}
return a.File < b.File
}
func main() {
const fen = "8/8/8/8/3B4/2r5/8/8"
storage, _ := uci.DecodePieceStorage(fen, pieces.NewPiece, boards.NewMapBoard)
pieces := storage.Pieces()
sort.Sort(ByPosition(pieces))
fmt.Printf("%+v\n", pieces)
// Output: [{Base:{kind:2 color:0 position:{File:2 Rank:2}}} {Base:{kind:3 color:1 position:{File:3 Rank:3}}}]
}uci.EncodePieceStorage():
package main
import (
"fmt"
"github.com/thewizardplusplus/go-chess-models/boards"
"github.com/thewizardplusplus/go-chess-models/common"
"github.com/thewizardplusplus/go-chess-models/encoding/uci"
"github.com/thewizardplusplus/go-chess-models/pieces"
)
func main() {
board := boards.NewMapBoard(common.Size{Width: 5, Height: 5}, []common.Piece{
pieces.NewRook(common.Black, common.Position{File: 2, Rank: 2}),
pieces.NewBishop(common.White, common.Position{File: 3, Rank: 3}),
})
fen := uci.EncodePieceStorage(board)
fmt.Printf("%v\n", fen)
// Output: 5/3B1/2r2/5/5
}The chessmodels.Perft() function using the boards.MapBoard structure:
BenchmarkPerft/MapBoard/initial/1Ply-8 486 2239365 ns/op 507723 B/op 13638 allocs/op
BenchmarkPerft/MapBoard/initial/2Ply-8 38 27071904 ns/op 6253672 B/op 165159 allocs/op
BenchmarkPerft/MapBoard/initial/3Ply-8 3 394039297 ns/op 91006645 B/op 2399815 allocs/op
BenchmarkPerft/MapBoard/kiwipete/1Ply-8 150 7844416 ns/op 1959120 B/op 47637 allocs/op
BenchmarkPerft/MapBoard/kiwipete/2Ply-8 4 311539966 ns/op 80169034 B/op 1892731 allocs/op
The chessmodels.Perft() function used the boards.SliceBoard structure:
BenchmarkPerft/SliceBoard/initial/1Ply-8 810 1419572 ns/op 684016 B/op 13646 allocs/op
BenchmarkPerft/SliceBoard/initial/2Ply-8 68 17883575 ns/op 8331384 B/op 165074 allocs/op
BenchmarkPerft/SliceBoard/initial/3Ply-8 4 253594389 ns/op 121325578 B/op 2399248 allocs/op
BenchmarkPerft/SliceBoard/kiwipete/1Ply-8 220 5340912 ns/op 2583824 B/op 47672 allocs/op
BenchmarkPerft/SliceBoard/kiwipete/2Ply-8 5 208109435 ns/op 103011680 B/op 1895999 allocs/op
The chessmodels.Perft() function used the boards.BitBoard structure:
BenchmarkPerft/BitBoard/initial/1Ply-8 284 4036298 ns/op 958048 B/op 35888 allocs/op
BenchmarkPerft/BitBoard/initial/2Ply-8 20 54032966 ns/op 11627104 B/op 433592 allocs/op
BenchmarkPerft/BitBoard/initial/3Ply-8 2 708741154 ns/op 169201536 B/op 6300499 allocs/op
BenchmarkPerft/BitBoard/kiwipete/1Ply-8 74 14372268 ns/op 3546305 B/op 124803 allocs/op
BenchmarkPerft/BitBoard/kiwipete/2Ply-8 2 637371490 ns/op 138270896 B/op 4866744 allocs/op
- go-chess-perft — utility for counting all possible moves (based on the perft function)
- go-chess-moves — utility for generating all possible chess moves
- go-chess-comparator — utility for comparing the generation of all possible chess moves by different board representations
The MIT License (MIT)
Copyright © 2019, 2022-2023 thewizardplusplus