tabula/board.go

722 lines
20 KiB
Go

package tabula
import (
"log"
"math"
"sort"
"sync"
)
var (
AnalysisBufferSize = 128
SubAnalysisBufferSize = 3072
)
const (
SpaceHomePlayer = 0
SpaceHomeOpponent = 25
SpaceBarPlayer = 26
SpaceBarOpponent = 27
SpaceRoll1 = 28
SpaceRoll2 = 29
SpaceRoll3 = 30
SpaceRoll4 = 31
SpaceEnteredPlayer = 32 // Whether the player has fully entered the board. Only used in acey-deucey games.
SpaceEnteredOpponent = 33 // Whether the opponent has fully entered the board. Only used in acey-deucey games.
SpaceAcey = 34 // 0 - Backgammon, 1 - Acey-deucey.
)
const (
boardSpaces = 35
)
// Board represents the state of a game. It contains spaces for the checkers,
// as well as four "spaces" which contain the available die rolls.
type Board [boardSpaces]int8
// NewBoard returns a new board with checkers placed in their starting positions.
func NewBoard(acey bool) Board {
if acey {
return Board{15, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -15, 0, 0, 0, 0, 0, 0, 0, 0, 1}
}
return Board{0, -2, 0, 0, 0, 0, 5, 0, 3, 0, 0, 0, -5, 5, 0, 0, 0, -3, 0, -5, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0}
}
func (b Board) Acey() bool {
return b[SpaceAcey] == 1
}
func (b Board) SetValue(space int, value int8) Board {
b[space] = value
return b
}
// Move moves a checker on the board.
func (b Board) Move(from int, to int, player int) Board {
if b[from] == 0 || (player == 1 && b[from] < 0) || (player == 2 && b[from] > 0) {
log.Panic("illegal move: no from checker", from, to, player)
} else if b[to] != 0 {
if (player == 1 && b[to] == -1) || (player == 2 && b[to] == 1) {
b[to] = 0
if player == 1 {
b[SpaceBarOpponent]--
} else {
b[SpaceBarPlayer]++
}
} else if (player == 1 && b[to] < 0) || (player == 2 && b[to] > 0) {
b.Print()
log.Panic("illegal move: existing checkers at to space", from, to, player, b[to])
}
}
delta := int8(1)
if player == 2 {
delta = int8(-1)
}
b[from], b[to] = b[from]-delta, b[to]+delta
return b
}
// Checkers returns the number of checkers at a space. It always returns a positive number.
func (b Board) Checkers(player int, space int) int {
v := b[space]
if player == 1 && v > 0 {
return int(v)
} else if player == 2 && v < 0 {
return int(v * -1)
}
return 0
}
func (b Board) MayBearOff(player int) bool {
if b.Acey() && ((player == 1 && b[SpaceEnteredPlayer] == 0) || (player == 2 && b[SpaceEnteredOpponent] == 0)) {
return false
}
homeStart := 1
homeEnd := 6
barSpace := SpaceBarPlayer
if player == 2 {
homeStart = 19
homeEnd = 24
barSpace = SpaceBarOpponent
}
if b.Checkers(player, barSpace) != 0 {
return false
}
for space := 1; space < 25; space++ {
if space >= homeStart && space <= homeEnd {
continue
} else if b.Checkers(player, space) != 0 {
return false
}
}
return true
}
func (b Board) spaceDiff(player int, from int, to int) int {
switch {
case from < 0 || from > 27 || to < 0 || to > 27:
return 0
case to == SpaceBarPlayer || to == SpaceBarOpponent:
return 0
case (from == SpaceBarPlayer || from == SpaceBarOpponent) && (to == SpaceBarPlayer || to == SpaceBarOpponent || to == SpaceHomePlayer || to == SpaceHomeOpponent):
return 0
case to == SpaceHomePlayer:
return from
case to == SpaceHomeOpponent:
return 25 - from
case from == SpaceHomePlayer || from == SpaceHomeOpponent:
if b.Acey() {
if player == 1 && from == SpaceHomePlayer && b[SpaceEnteredPlayer] == 0 {
return 25 - to
} else if player == 2 && from == SpaceHomeOpponent && b[SpaceEnteredOpponent] == 0 {
return to
}
}
return 0
case from == SpaceBarPlayer:
return 25 - to
case from == SpaceBarOpponent:
return to
default:
diff := to - from
if diff < 0 {
return diff * -1
}
return diff
}
}
// HaveRoll returns whether the player has a sufficient die roll for the specified move.
func (b Board) HaveRoll(from int, to int, player int) bool {
barSpace := SpaceBarPlayer
if player == 2 {
barSpace = SpaceBarOpponent
}
if b[barSpace] != 0 && from != barSpace {
return false
}
delta := int8(b.spaceDiff(player, from, to))
if delta == 0 {
return false
}
playerDelta := -1
playerHomeEnd := 6
if player == 2 {
playerDelta = 1
playerHomeEnd = 19
}
if b.MayBearOff(player) && !b.Acey() {
allowGreater := true
for checkSpace := int8(0); checkSpace < 6-delta; checkSpace++ {
if b.Checkers(player, playerHomeEnd+int(checkSpace)*playerDelta) != 0 {
allowGreater = false
break
}
}
if allowGreater {
return (b[SpaceRoll1] >= delta || b[SpaceRoll2] >= delta || b[SpaceRoll3] >= delta || b[SpaceRoll4] >= delta)
}
}
return (b[SpaceRoll1] == delta || b[SpaceRoll2] == delta || b[SpaceRoll3] == delta || b[SpaceRoll4] == delta)
}
// UseRoll uses a die roll.
func (b Board) UseRoll(from int, to int, player int) Board {
delta := int8(b.spaceDiff(player, from, to))
if delta == 0 {
b.Print()
log.Panic("unknown space diff", from, to, player)
}
playerDelta := -1
playerHomeEnd := 6
if player == 2 {
playerDelta = 1
playerHomeEnd = 19
}
var allowGreater bool
if b.MayBearOff(player) && !b.Acey() {
allowGreater = true
for checkSpace := int8(0); checkSpace < 6-delta; checkSpace++ {
if b.Checkers(player, playerHomeEnd+int(checkSpace)*playerDelta) != 0 {
allowGreater = false
break
}
}
}
if allowGreater {
switch {
case b[SpaceRoll1] >= delta:
b[SpaceRoll1] = 0
case b[SpaceRoll2] >= delta:
b[SpaceRoll2] = 0
case b[SpaceRoll3] >= delta:
b[SpaceRoll3] = 0
case b[SpaceRoll4] >= delta:
b[SpaceRoll4] = 0
default:
b.Print()
log.Panic("no available roll for move", from, to, player, delta)
}
} else {
switch {
case b[SpaceRoll1] == delta:
b[SpaceRoll1] = 0
case b[SpaceRoll2] == delta:
b[SpaceRoll2] = 0
case b[SpaceRoll3] == delta:
b[SpaceRoll3] = 0
case b[SpaceRoll4] == delta:
b[SpaceRoll4] = 0
default:
b.Print()
log.Panic("no available roll for move", from, to, player, delta)
}
}
return b
}
func (b Board) _available(player int) [][]int {
homeSpace := SpaceHomePlayer
barSpace := SpaceBarPlayer
opponentBarSpace := SpaceBarOpponent
if player == 2 {
homeSpace = SpaceHomeOpponent
barSpace = SpaceBarOpponent
opponentBarSpace = SpaceBarPlayer
}
mayBearOff := b.MayBearOff(player)
onBar := b[barSpace] != 0
var moves [][]int
if b.Acey() && ((player == 1 && b[SpaceEnteredPlayer] == 0) || (player == 2 && b[SpaceEnteredOpponent] == 0)) && b[homeSpace] != 0 {
for space := 1; space < 25; space++ {
v := b[space]
if ((player == 1 && v >= -1) || (player == 2 && v <= 1)) && b.HaveRoll(homeSpace, space, player) {
moves = append(moves, []int{homeSpace, space})
}
}
}
for from := 0; from < 28; from++ {
if from == SpaceHomePlayer || from == SpaceHomeOpponent || from == opponentBarSpace || b.Checkers(player, from) == 0 || (onBar && from != barSpace) {
continue
}
if player == 1 {
for to := 0; to < from; to++ {
if to == SpaceBarPlayer || to == SpaceBarOpponent || to == SpaceHomeOpponent || (to == SpaceHomePlayer && !mayBearOff) {
continue
}
v := b[to]
if (player == 1 && v < -1) || (player == 2 && v > 1) || !b.HaveRoll(from, to, player) {
continue
}
moves = append(moves, []int{from, to})
}
} else { // TODO clean up
start := from + 1
if from == SpaceBarOpponent {
start = 0
}
for to := start; to <= 25; to++ {
if to == SpaceBarPlayer || to == SpaceBarOpponent || to == SpaceHomeOpponent || (to == SpaceHomeOpponent && !mayBearOff) {
continue
}
v := b[to]
if (player == 1 && v < -1) || (player == 2 && v > 1) || !b.HaveRoll(from, to, player) {
continue
}
moves = append(moves, []int{from, to})
}
}
}
return moves
}
// Available returns legal moves available.
func (b Board) Available(player int) ([][][]int, []Board) {
var allMoves [][][]int
resultMutex := &sync.Mutex{}
movesFound := func(moves [][]int) bool {
resultMutex.Lock()
for _, f := range allMoves {
if movesEqual(f, moves) {
resultMutex.Unlock()
return true
}
}
resultMutex.Unlock()
return false
}
var boards []Board
a := b._available(player)
maxLen := 1
for _, move := range a {
move := move
newBoard := b.Move(move[0], move[1], player).UseRoll(move[0], move[1], player)
newAvailable := newBoard._available(player)
if len(newAvailable) == 0 {
moves := [][]int{move}
if !movesFound(moves) {
allMoves = append(allMoves, moves)
boards = append(boards, newBoard)
}
continue
}
for _, move2 := range newAvailable {
newBoard2 := newBoard.Move(move2[0], move2[1], player).UseRoll(move2[0], move2[1], player)
newAvailable2 := newBoard2._available(player)
if len(newAvailable2) == 0 {
moves := [][]int{move, move2}
if !movesFound(moves) {
allMoves = append(allMoves, moves)
boards = append(boards, newBoard2)
maxLen = 2
}
continue
}
for _, move3 := range newAvailable2 {
newBoard3 := newBoard2.Move(move3[0], move3[1], player).UseRoll(move3[0], move3[1], player)
newAvailable3 := newBoard3._available(player)
if len(newAvailable3) == 0 {
moves := [][]int{move, move2, move3}
if !movesFound(moves) {
allMoves = append(allMoves, moves)
boards = append(boards, newBoard3)
maxLen = 3
}
continue
}
for _, move4 := range newAvailable3 {
newBoard4 := newBoard3.Move(move4[0], move4[1], player).UseRoll(move4[0], move4[1], player)
moves := [][]int{move, move2, move3, move4}
if !movesFound(moves) {
allMoves = append(allMoves, moves)
boards = append(boards, newBoard4)
maxLen = 4
}
}
}
}
}
var newMoves [][][]int
for i := 0; i < len(allMoves); i++ {
if len(allMoves[i]) >= maxLen {
newMoves = append(newMoves, allMoves[i])
}
}
return newMoves, boards
}
func (b Board) Past() bool {
if b[SpaceBarPlayer] != 0 || b[SpaceBarOpponent] != 0 {
return false
}
var playerFirst, opponentLast int
for space := 1; space < 25; space++ {
v := b[space]
if v == 0 {
continue
} else if v > 0 {
if space > playerFirst {
playerFirst = space
}
} else {
if opponentLast == 0 {
opponentLast = space
}
}
}
return playerFirst < opponentLast
}
func (b Board) Pips(player int) int {
var pips int
if b.Acey() {
if player == 1 && b[SpaceEnteredPlayer] == 0 {
pips += int(b.Checkers(player, SpaceHomePlayer)) * PseudoPips(player, SpaceHomePlayer)
} else if player == 2 && b[SpaceEnteredOpponent] == 0 {
pips += int(b.Checkers(player, SpaceHomeOpponent)) * PseudoPips(player, SpaceHomeOpponent)
}
}
if player == 1 {
pips += int(b.Checkers(player, SpaceBarPlayer)) * PseudoPips(player, SpaceBarPlayer)
} else {
pips += int(b.Checkers(player, SpaceBarOpponent)) * PseudoPips(player, SpaceBarOpponent)
}
for space := 1; space < 25; space++ {
pips += int(b.Checkers(player, space)) * PseudoPips(player, space)
}
return pips
}
func (b Board) Blots(player int) int {
o := opponent(player)
var pips int
for space := 1; space < 25; space++ {
checkers := b.Checkers(player, space)
if checkers != 1 {
continue
}
pips += checkers * PseudoPips(o, space)
}
return pips
}
func (b Board) evaluate(player int, hitScore int, a *Analysis) {
pips := b.Pips(player)
score := float64(pips)
var blots int
if !a.Past {
blots = b.Blots(player)
score += float64(blots)*WeightBlot + float64(hitScore)*WeightHit
}
a.Pips = pips
a.Blots = blots
a.Hits = hitScore
a.PlayerScore = score
a.hitScore = hitScore
}
func (b Board) Evaluation(player int, hitScore int, moves [][]int) *Analysis {
a := &Analysis{
Board: b,
Moves: moves,
Past: b.Past(),
player: player,
chance: 1,
}
b.evaluate(player, hitScore, a)
return a
}
func (b Board) Analyze(available [][][]int, result *[]*Analysis) {
if len(available) == 0 {
*result = (*result)[:0]
return
}
var reuse []*[]*Analysis
for _, r := range *result {
if r.result != nil {
reuse = append(reuse, r.result)
}
}
*result = (*result)[:0]
reuseLen := len(reuse)
var reuseIndex int
w := &sync.WaitGroup{}
past := b.Past()
w.Add(len(available))
for _, moves := range available {
var r *[]*Analysis
if reuseIndex < reuseLen {
r = reuse[reuseIndex]
*r = (*r)[:0]
reuseIndex++
} else {
v := make([]*Analysis, 0, SubAnalysisBufferSize)
r = &v
}
a := &Analysis{
Board: b,
Moves: moves,
Past: past,
player: 1,
chance: 1,
result: r,
resultMutex: &sync.Mutex{},
wg: w,
}
*result = append(*result, a)
analysisQueue <- a
}
w.Wait()
for _, a := range *result {
if a.player == 1 && !a.Past {
var oppPips float64
var oppBlots float64
var oppHits float64
var oppScore float64
var count float64
for _, r := range *a.result {
oppPips += float64(r.Pips)
oppBlots += float64(r.Blots)
oppHits += float64(r.Hits)
oppScore += r.PlayerScore
count++
}
if count == 0 {
a.Score = a.PlayerScore
} else {
a.OppPips = (oppPips / count)
a.OppBlots = (oppBlots / count)
a.OppHits = (oppHits / count)
a.OppScore = (oppScore / count)
score := a.PlayerScore
if !math.IsNaN(oppScore) {
score += a.OppScore * WeightOppScore
}
a.Score = score
}
} else {
a.Score = a.PlayerScore
}
}
sort.Slice(*result, func(i, j int) bool {
return (*result)[i].Score < (*result)[j].Score
})
}
func (b Board) ChooseDoubles(result *[]*Analysis) int {
if !b.Acey() {
return 0
}
bestDoubles := 6
bestScore := math.MaxFloat64
var available [][][]int
for i := 0; i < 6; i++ {
doubles := int8(i + 1)
bc := b
bc[SpaceRoll1], bc[SpaceRoll2], bc[SpaceRoll3], bc[SpaceRoll4] = doubles, doubles, doubles, doubles
available, _ = bc.Available(1)
bc.Analyze(available, result)
if len(*result) > 0 && (*result)[0].Score < bestScore {
bestDoubles = i + 1
bestScore = (*result)[0].Score
}
}
return bestDoubles
}
func (b Board) Print() {
log.Printf("%+v", b)
}
func opponent(player int) int {
if player == 1 {
return 2
}
return 1
}
func spaceValue(player int, space int) int {
if space == SpaceHomePlayer || space == SpaceHomeOpponent || space == SpaceBarPlayer || space == SpaceBarOpponent {
return 25
} else if player == 1 {
return space
} else {
return 25 - space
}
}
func PseudoPips(player int, space int) int {
v := 6 + spaceValue(player, space) + int(math.Exp(float64(spaceValue(player, space))*0.2))*2
if space == SpaceHomePlayer || space == SpaceHomeOpponent || (player == 1 && (space > 6 || space == SpaceBarPlayer)) || (player == 2 && (space < 19 || space == SpaceBarOpponent)) {
v += 24
}
return v
}
func movesEqual(a [][]int, b [][]int) bool {
l := len(a)
if len(b) != l {
return false
}
for _, m := range a {
switch m[0] {
case SpaceBarPlayer, SpaceBarOpponent:
return false
}
switch m[1] {
case SpaceHomePlayer, SpaceHomeOpponent:
return false
}
}
switch l {
case 0:
return true
case 1:
return a[0][0] == b[0][0] && a[0][1] == b[0][1]
case 2:
return (a[0][0] == b[0][0] && a[0][1] == b[0][1] && a[1][0] == b[1][0] && a[1][1] == b[1][1]) || // 1, 2
(a[0][0] == b[1][0] && a[0][1] == b[1][1] && a[1][0] == b[0][0] && a[1][1] == b[0][1]) // 2, 1
case 3:
if a[0][0] == b[0][0] && a[0][1] == b[0][1] { // 1
if (a[1][0] == b[1][0] && a[1][1] == b[1][1] && a[2][0] == b[2][0] && a[2][1] == b[2][1]) || // 2, 3
(a[1][0] == b[2][0] && a[1][1] == b[2][1] && a[2][0] == b[1][0] && a[2][1] == b[1][1]) { // 3, 2
return true
}
}
if a[0][0] == b[1][0] && a[0][1] == b[1][1] { // 2
if (a[1][0] == b[0][0] && a[1][1] == b[0][1] && a[2][0] == b[2][0] && a[2][1] == b[2][1]) ||
(a[1][0] == b[2][0] && a[1][1] == b[2][1] && a[2][0] == b[0][0] && a[2][1] == b[0][1]) {
return true
}
}
if a[0][0] == b[2][0] && a[0][1] == b[2][1] { // 3
if (a[1][0] == b[0][0] && a[1][1] == b[0][1] && a[2][0] == b[1][0] && a[2][1] == b[1][1]) || // 1, 2
(a[1][0] == b[1][0] && a[1][1] == b[1][1] && a[2][0] == b[0][0] && a[2][1] == b[0][1]) { // 2, 1
return true
}
}
return false
case 4:
if a[0][0] == b[0][0] && a[0][1] == b[0][1] { // 1
if a[1][0] == b[1][0] && a[1][1] == b[1][1] { // 2
if (a[2][0] == b[2][0] && a[2][1] == b[2][1] && a[3][0] == b[3][0] && a[3][1] == b[3][1]) || // 3,4
(a[2][0] == b[3][0] && a[2][1] == b[3][1] && a[3][0] == b[2][0] && a[3][1] == b[2][1]) { // 4,3
return true
}
}
if a[1][0] == b[2][0] && a[1][1] == b[2][1] { // 3
if (a[2][0] == b[1][0] && a[2][1] == b[1][1] && a[3][0] == b[3][0] && a[3][1] == b[3][1]) || // 2,4
(a[2][0] == b[3][0] && a[2][1] == b[3][1] && a[3][0] == b[1][0] && a[3][1] == b[1][1]) { // 4,2
return true
}
}
if a[1][0] == b[3][0] && a[1][1] == b[3][1] { // 4
if (a[2][0] == b[2][0] && a[2][1] == b[2][1] && a[3][0] == b[1][0] && a[3][1] == b[1][1]) || // 3,2
(a[2][0] == b[1][0] && a[2][1] == b[1][1] && a[3][0] == b[2][0] && a[3][1] == b[2][1]) { // 2,3
return true
}
}
}
if a[0][0] == b[1][0] && a[0][1] == b[1][1] { // 2
if a[1][0] == b[0][0] && a[1][1] == b[0][1] { // 1
if (a[2][0] == b[2][0] && a[2][1] == b[2][1] && a[3][0] == b[3][0] && a[3][1] == b[3][1]) || // 3,4
(a[2][0] == b[3][0] && a[2][1] == b[3][1] && a[3][0] == b[2][0] && a[3][1] == b[2][1]) { // 4,3
return true
}
}
if a[1][0] == b[2][0] && a[1][1] == b[2][1] { // 3
if (a[2][0] == b[3][0] && a[2][1] == b[3][1] && a[3][0] == b[0][0] && a[3][1] == b[0][1]) || // 4,1
(a[2][0] == b[0][0] && a[2][1] == b[0][1] && a[3][0] == b[3][0] && a[3][1] == b[3][1]) { // 1,4
return true
}
}
if a[1][0] == b[3][0] && a[1][1] == b[3][1] { // 4
if (a[2][0] == b[2][0] && a[2][1] == b[2][1] && a[3][0] == b[0][0] && a[3][1] == b[0][1]) || // 3,1
(a[2][0] == b[0][0] && a[2][1] == b[0][1] && a[3][0] == b[2][0] && a[3][1] == b[2][1]) { // 1,3
return true
}
}
}
if a[0][0] == b[2][0] && a[0][1] == b[2][1] { // 3
if a[1][0] == b[0][0] && a[1][1] == b[0][1] { // 1
if (a[2][0] == b[1][0] && a[2][1] == b[1][1] && a[3][0] == b[3][0] && a[3][1] == b[3][1]) || // 2,4
(a[2][0] == b[3][0] && a[2][1] == b[3][1] && a[3][0] == b[1][0] && a[3][1] == b[1][1]) { // 4,2
return true
}
}
if a[1][0] == b[1][0] && a[1][1] == b[1][1] { // 2
if (a[2][0] == b[0][0] && a[2][1] == b[0][1] && a[3][0] == b[3][0] && a[3][1] == b[3][1]) || // 1,4
(a[2][0] == b[3][0] && a[2][1] == b[3][1] && a[3][0] == b[0][0] && a[3][1] == b[0][1]) { // 4,1
return true
}
}
if a[1][0] == b[3][0] && a[1][1] == b[3][1] { // 4
if (a[2][0] == b[1][0] && a[2][1] == b[1][1] && a[3][0] == b[0][0] && a[3][1] == b[0][1]) || // 2,1
(a[2][0] == b[0][0] && a[2][1] == b[0][1] && a[3][0] == b[1][0] && a[3][1] == b[1][1]) { // 1,2
return true
}
}
}
if a[0][0] == b[3][0] && a[0][1] == b[3][1] { // 4
if a[1][0] == b[0][0] && a[1][1] == b[0][1] { // 1
if (a[2][0] == b[2][0] && a[2][1] == b[2][1] && a[3][0] == b[1][0] && a[3][1] == b[1][1]) || // 3,2
(a[2][0] == b[1][0] && a[2][1] == b[1][1] && a[3][0] == b[2][0] && a[3][1] == b[2][1]) { // 2,3
return true
}
}
if a[1][0] == b[1][0] && a[1][1] == b[1][1] { // 2
if (a[2][0] == b[0][0] && a[2][1] == b[0][1] && a[3][0] == b[2][0] && a[3][1] == b[2][1]) || // 1,3
(a[2][0] == b[2][0] && a[2][1] == b[2][1] && a[3][0] == b[0][0] && a[3][1] == b[0][1]) { // 3,1
return true
}
}
if a[1][0] == b[2][0] && a[1][1] == b[2][1] { // 3
if (a[2][0] == b[0][0] && a[2][1] == b[0][1] && a[3][0] == b[1][0] && a[3][1] == b[1][1]) || // 1,2
(a[2][0] == b[1][0] && a[2][1] == b[1][1] && a[3][0] == b[0][0] && a[3][1] == b[0][1]) { // 2,1
return true
}
}
}
return false
default:
log.Panicf("more than 4 moves were provided: %+v %+v", a, b)
return false
}
}