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triple double pawns: Also count positions with spaces in between #2

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triple double pawns: Also count positions with spaces in between #2

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21 changes: 11 additions & 10 deletions js/goals/piece-structures.js
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Original file line number Diff line number Diff line change
Expand Up @@ -12,18 +12,19 @@ module.exports = {
},

tripleDoublePawns: function (position) {
// Fast check for any kind of doubled pawns to quickly eliminate most positions
if (!/P[A-Za-z.]{7}P|p[A-Za-z.]{7}p/.test(position)) {
return false
}

for (const piece of ['P', 'p']) {
const inFile = new Set()
const re = new RegExp(`${piece}(?=[A-Za-z.]{7}${piece})`, 'g')
for (const m of position.matchAll(re)) {
inFile.add(m.index % 8)
let doublePawnCount = 0
for (let file = 0; file < 8; file++) {
let pawnsOnFile = 0
for (let rank = 1; rank < 7; rank++) {
if (position[file + rank * 8] === piece) {
pawnsOnFile++
}
}
if (pawnsOnFile >= 2) doublePawnCount++
}
if (inFile.size > 2) {

if (doublePawnCount >= 3) {
return piece === 'P' ? 'white' : 'black'
}
}
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10 changes: 10 additions & 0 deletions tests/pawn-stacks.test.js
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Original file line number Diff line number Diff line change
Expand Up @@ -50,6 +50,16 @@ test('test quad pawns do not count for triple double pawns', () => {
expect(pieceStructures.tripleDoublePawns(fenToPosition(fen))).toBe(false)
})

test('triple double pawns with spaces in between', () => {
let fen = '4k3/6P1/5n2/1N1P2P1/1P1q4/3P4/1P6/4K3 w - - 0 1'
expect(pieceStructures.tripleDoublePawns(fenToPosition(fen))).toBe('white')
})

test('realistic position of triple double pawns with spaces in between', () => {
let fen = '4k3/q2p3p/p6p/P6p/P1P3Qp/7P/2P4P/4K3 w - - 0 1'
expect(pieceStructures.tripleDoublePawns(fenToPosition(fen))).toBe('white')
})

test('test 6 pawns in the same file', () => {
let fen = 'k7/3p4/3p4/3p4/3P4/3P4/3P4/K7 w - - 0 1'
expect(pieceStructures.sixPawnsInTheSameFile(fenToPosition(fen))).toBe(true)
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