2 Stockfish, a UCI chess playing engine derived from Glaurung 2.1
3 Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
4 Copyright (C) 2008-2013 Marco Costalba, Joona Kiiski, Tord Romstad
6 Stockfish is free software: you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation, either version 3 of the License, or
9 (at your option) any later version.
11 Stockfish is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with this program. If not, see <http://www.gnu.org/licenses/>.
30 #include "ucioption.h"
34 enum ExtendedPieceType { // Used for tracing
35 PST = 8, IMBALANCE, MOBILITY, THREAT, PASSED, UNSTOPPABLE, SPACE, TOTAL
40 Score scores[COLOR_NB][TOTAL + 1];
41 std::stringstream stream;
43 void add(int idx, Score term_w, Score term_b = SCORE_ZERO);
44 void row(const char* name, int idx);
45 std::string do_trace(const Position& pos);
48 // Struct EvalInfo contains various information computed and collected
49 // by the evaluation functions.
52 // Pointers to material and pawn hash table entries
56 // attackedBy[color][piece type] is a bitboard representing all squares
57 // attacked by a given color and piece type, attackedBy[color][ALL_PIECES]
58 // contains all squares attacked by the given color.
59 Bitboard attackedBy[COLOR_NB][PIECE_TYPE_NB];
61 // kingRing[color] is the zone around the king which is considered
62 // by the king safety evaluation. This consists of the squares directly
63 // adjacent to the king, and the three (or two, for a king on an edge file)
64 // squares two ranks in front of the king. For instance, if black's king
65 // is on g8, kingRing[BLACK] is a bitboard containing the squares f8, h8,
66 // f7, g7, h7, f6, g6 and h6.
67 Bitboard kingRing[COLOR_NB];
69 // kingAttackersCount[color] is the number of pieces of the given color
70 // which attack a square in the kingRing of the enemy king.
71 int kingAttackersCount[COLOR_NB];
73 // kingAttackersWeight[color] is the sum of the "weight" of the pieces of the
74 // given color which attack a square in the kingRing of the enemy king. The
75 // weights of the individual piece types are given by the variables
76 // QueenAttackWeight, RookAttackWeight, BishopAttackWeight and
77 // KnightAttackWeight in evaluate.cpp
78 int kingAttackersWeight[COLOR_NB];
80 // kingAdjacentZoneAttacksCount[color] is the number of attacks to squares
81 // directly adjacent to the king of the given color. Pieces which attack
82 // more than one square are counted multiple times. For instance, if black's
83 // king is on g8 and there's a white knight on g5, this knight adds
84 // 2 to kingAdjacentZoneAttacksCount[BLACK].
85 int kingAdjacentZoneAttacksCount[COLOR_NB];
88 // Evaluation grain size, must be a power of 2
89 const int GrainSize = 4;
91 // Evaluation weights, initialized from UCI options
92 enum { Mobility, PawnStructure, PassedPawns, Space, KingDangerUs, KingDangerThem };
96 #define S(mg, eg) make_score(mg, eg)
98 // Internal evaluation weights. These are applied on top of the evaluation
99 // weights read from UCI parameters. The purpose is to be able to change
100 // the evaluation weights while keeping the default values of the UCI
101 // parameters at 100, which looks prettier.
103 // Values modified by Joona Kiiski
104 const Score WeightsInternal[] = {
105 S(289, 344), S(233, 201), S(221, 273), S(46, 0), S(271, 0), S(307, 0)
108 // MobilityBonus[PieceType][attacked] contains bonuses for middle and end
109 // game, indexed by piece type and number of attacked squares not occupied by
111 const Score MobilityBonus[][32] = {
113 { S(-35,-30), S(-22,-20), S(-9,-10), S( 3, 0), S(15, 10), S(27, 20), // Knights
114 S( 37, 28), S( 42, 31), S(44, 33) },
115 { S(-22,-27), S( -8,-13), S( 6, 1), S(20, 15), S(34, 29), S(48, 43), // Bishops
116 S( 60, 55), S( 68, 63), S(74, 68), S(77, 72), S(80, 75), S(82, 77),
117 S( 84, 79), S( 86, 81) },
118 { S(-17,-33), S(-11,-16), S(-5, 0), S( 1, 16), S( 7, 32), S(13, 48), // Rooks
119 S( 18, 64), S( 22, 80), S(26, 96), S(29,109), S(31,115), S(33,119),
120 S( 35,122), S( 36,123), S(37,124) },
121 { S(-12,-20), S( -8,-13), S(-5, -7), S(-2, -1), S( 1, 5), S( 4, 11), // Queens
122 S( 7, 17), S( 10, 23), S(13, 29), S(16, 34), S(18, 38), S(20, 40),
123 S( 22, 41), S( 23, 41), S(24, 41), S(25, 41), S(25, 41), S(25, 41),
124 S( 25, 41), S( 25, 41), S(25, 41), S(25, 41), S(25, 41), S(25, 41),
125 S( 25, 41), S( 25, 41), S(25, 41), S(25, 41) }
128 // Outpost[PieceType][Square] contains bonuses of knights and bishops, indexed
129 // by piece type and square (from white's point of view).
130 const Value Outpost[][SQUARE_NB] = {
133 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0), // Knights
134 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0),
135 V(0), V(0), V(4), V(8), V(8), V(4), V(0), V(0),
136 V(0), V(4),V(17),V(26),V(26),V(17), V(4), V(0),
137 V(0), V(8),V(26),V(35),V(35),V(26), V(8), V(0),
138 V(0), V(4),V(17),V(17),V(17),V(17), V(4), V(0) },
140 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0), // Bishops
141 V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0),
142 V(0), V(0), V(5), V(5), V(5), V(5), V(0), V(0),
143 V(0), V(5),V(10),V(10),V(10),V(10), V(5), V(0),
144 V(0),V(10),V(21),V(21),V(21),V(21),V(10), V(0),
145 V(0), V(5), V(8), V(8), V(8), V(8), V(5), V(0) }
148 // Threat[attacking][attacked] contains bonuses according to which piece
149 // type attacks which one.
150 const Score Threat[][PIECE_TYPE_NB] = {
152 { S(0, 0), S( 7, 39), S( 0, 0), S(24, 49), S(41,100), S(41,100) }, // KNIGHT
153 { S(0, 0), S( 7, 39), S(24, 49), S( 0, 0), S(41,100), S(41,100) }, // BISHOP
154 { S(0, 0), S( 0, 22), S(15, 49), S(15, 49), S( 0, 0), S(24, 49) }, // ROOK
155 { S(0, 0), S(15, 39), S(15, 39), S(15, 39), S(15, 39), S( 0, 0) } // QUEEN
158 // ThreatenedByPawn[PieceType] contains a penalty according to which piece
159 // type is attacked by an enemy pawn.
160 const Score ThreatenedByPawn[] = {
161 S(0, 0), S(0, 0), S(56, 70), S(56, 70), S(76, 99), S(86, 118)
166 const Score Tempo = make_score(24, 11);
167 const Score BishopPin = make_score(66, 11);
168 const Score RookOn7th = make_score(11, 20);
169 const Score QueenOn7th = make_score( 3, 8);
170 const Score RookOnPawn = make_score(10, 28);
171 const Score QueenOnPawn = make_score( 4, 20);
172 const Score RookOpenFile = make_score(43, 21);
173 const Score RookSemiopenFile = make_score(19, 10);
174 const Score BishopPawns = make_score( 8, 12);
175 const Score MinorBehindPawn = make_score(16, 0);
176 const Score UndefendedMinor = make_score(25, 10);
177 const Score TrappedRook = make_score(90, 0);
179 // Penalty for a bishop on a1/h1 (a8/h8 for black) which is trapped by
180 // a friendly pawn on b2/g2 (b7/g7 for black). This can obviously only
181 // happen in Chess960 games.
182 const Score TrappedBishopA1H1 = make_score(50, 50);
184 // The SpaceMask[Color] contains the area of the board which is considered
185 // by the space evaluation. In the middle game, each side is given a bonus
186 // based on how many squares inside this area are safe and available for
187 // friendly minor pieces.
188 const Bitboard SpaceMask[] = {
189 (1ULL << SQ_C2) | (1ULL << SQ_D2) | (1ULL << SQ_E2) | (1ULL << SQ_F2) |
190 (1ULL << SQ_C3) | (1ULL << SQ_D3) | (1ULL << SQ_E3) | (1ULL << SQ_F3) |
191 (1ULL << SQ_C4) | (1ULL << SQ_D4) | (1ULL << SQ_E4) | (1ULL << SQ_F4),
192 (1ULL << SQ_C7) | (1ULL << SQ_D7) | (1ULL << SQ_E7) | (1ULL << SQ_F7) |
193 (1ULL << SQ_C6) | (1ULL << SQ_D6) | (1ULL << SQ_E6) | (1ULL << SQ_F6) |
194 (1ULL << SQ_C5) | (1ULL << SQ_D5) | (1ULL << SQ_E5) | (1ULL << SQ_F5)
197 // King danger constants and variables. The king danger scores are taken
198 // from the KingDanger[]. Various little "meta-bonuses" measuring
199 // the strength of the enemy attack are added up into an integer, which
200 // is used as an index to KingDanger[].
202 // KingAttackWeights[PieceType] contains king attack weights by piece type
203 const int KingAttackWeights[] = { 0, 0, 2, 2, 3, 5 };
205 // Bonuses for enemy's safe checks
206 const int QueenContactCheck = 6;
207 const int RookContactCheck = 4;
208 const int QueenCheck = 3;
209 const int RookCheck = 2;
210 const int BishopCheck = 1;
211 const int KnightCheck = 1;
213 // KingExposed[Square] contains penalties based on the position of the
214 // defending king, indexed by king's square (from white's point of view).
215 const int KingExposed[] = {
216 2, 0, 2, 5, 5, 2, 0, 2,
217 2, 2, 4, 8, 8, 4, 2, 2,
218 7, 10, 12, 12, 12, 12, 10, 7,
219 15, 15, 15, 15, 15, 15, 15, 15,
220 15, 15, 15, 15, 15, 15, 15, 15,
221 15, 15, 15, 15, 15, 15, 15, 15,
222 15, 15, 15, 15, 15, 15, 15, 15,
223 15, 15, 15, 15, 15, 15, 15, 15
226 // KingDanger[Color][attackUnits] contains the actual king danger weighted
227 // scores, indexed by color and by a calculated integer number.
228 Score KingDanger[COLOR_NB][128];
230 // Function prototypes
232 Value do_evaluate(const Position& pos, Value& margin);
235 void init_eval_info(const Position& pos, EvalInfo& ei);
237 template<Color Us, bool Trace>
238 Score evaluate_pieces_of_color(const Position& pos, EvalInfo& ei, Score& mobility);
240 template<Color Us, bool Trace>
241 Score evaluate_king(const Position& pos, const EvalInfo& ei, Value margins[]);
243 template<Color Us, bool Trace>
244 Score evaluate_threats(const Position& pos, const EvalInfo& ei);
246 template<Color Us, bool Trace>
247 Score evaluate_passed_pawns(const Position& pos, const EvalInfo& ei);
250 int evaluate_space(const Position& pos, const EvalInfo& ei);
252 Score evaluate_unstoppable_pawns(const Position& pos, const EvalInfo& ei);
254 Value interpolate(const Score& v, Phase ph, ScaleFactor sf);
255 Score apply_weight(Score v, Score w);
256 Score weight_option(const std::string& mgOpt, const std::string& egOpt, Score internalWeight);
257 double to_cp(Value v);
263 /// evaluate() is the main evaluation function. It always computes two
264 /// values, an endgame score and a middle game score, and interpolates
265 /// between them based on the remaining material.
267 Value evaluate(const Position& pos, Value& margin) {
268 return do_evaluate<false>(pos, margin);
272 /// trace() is like evaluate() but instead of a value returns a string suitable
273 /// to be print on stdout with the detailed descriptions and values of each
274 /// evaluation term. Used mainly for debugging.
275 std::string trace(const Position& pos) {
276 return Tracing::do_trace(pos);
280 /// init() computes evaluation weights from the corresponding UCI parameters
281 /// and setup king tables.
285 Weights[Mobility] = weight_option("Mobility (Midgame)", "Mobility (Endgame)", WeightsInternal[Mobility]);
286 Weights[PawnStructure] = weight_option("Pawn Structure (Midgame)", "Pawn Structure (Endgame)", WeightsInternal[PawnStructure]);
287 Weights[PassedPawns] = weight_option("Passed Pawns (Midgame)", "Passed Pawns (Endgame)", WeightsInternal[PassedPawns]);
288 Weights[Space] = weight_option("Space", "Space", WeightsInternal[Space]);
289 Weights[KingDangerUs] = weight_option("Cowardice", "Cowardice", WeightsInternal[KingDangerUs]);
290 Weights[KingDangerThem] = weight_option("Aggressiveness", "Aggressiveness", WeightsInternal[KingDangerThem]);
292 const int MaxSlope = 30;
293 const int Peak = 1280;
295 for (int t = 0, i = 1; i < 100; i++)
297 t = std::min(Peak, std::min(int(0.4 * i * i), t + MaxSlope));
299 KingDanger[1][i] = apply_weight(make_score(t, 0), Weights[KingDangerUs]);
300 KingDanger[0][i] = apply_weight(make_score(t, 0), Weights[KingDangerThem]);
310 Value do_evaluate(const Position& pos, Value& margin) {
312 assert(!pos.checkers());
315 Value margins[COLOR_NB];
316 Score score, mobilityWhite, mobilityBlack;
317 Thread* th = pos.this_thread();
319 // margins[] store the uncertainty estimation of position's evaluation
320 // that typically is used by the search for pruning decisions.
321 margins[WHITE] = margins[BLACK] = VALUE_ZERO;
323 // Initialize score by reading the incrementally updated scores included
324 // in the position object (material + piece square tables) and adding
325 // Tempo bonus. Score is computed from the point of view of white.
326 score = pos.psq_score() + (pos.side_to_move() == WHITE ? Tempo : -Tempo);
328 // Probe the material hash table
329 ei.mi = Material::probe(pos, th->materialTable, th->endgames);
330 score += ei.mi->material_value();
332 // If we have a specialized evaluation function for the current material
333 // configuration, call it and return.
334 if (ei.mi->specialized_eval_exists())
337 return ei.mi->evaluate(pos);
340 // Probe the pawn hash table
341 ei.pi = Pawns::probe(pos, th->pawnsTable);
342 score += apply_weight(ei.pi->pawns_value(), Weights[PawnStructure]);
344 // Initialize attack and king safety bitboards
345 init_eval_info<WHITE>(pos, ei);
346 init_eval_info<BLACK>(pos, ei);
348 // Evaluate pieces and mobility
349 score += evaluate_pieces_of_color<WHITE, Trace>(pos, ei, mobilityWhite)
350 - evaluate_pieces_of_color<BLACK, Trace>(pos, ei, mobilityBlack);
352 score += apply_weight(mobilityWhite - mobilityBlack, Weights[Mobility]);
354 // Evaluate kings after all other pieces because we need complete attack
355 // information when computing the king safety evaluation.
356 score += evaluate_king<WHITE, Trace>(pos, ei, margins)
357 - evaluate_king<BLACK, Trace>(pos, ei, margins);
359 // Evaluate tactical threats, we need full attack information including king
360 score += evaluate_threats<WHITE, Trace>(pos, ei)
361 - evaluate_threats<BLACK, Trace>(pos, ei);
363 // Evaluate passed pawns, we need full attack information including king
364 score += evaluate_passed_pawns<WHITE, Trace>(pos, ei)
365 - evaluate_passed_pawns<BLACK, Trace>(pos, ei);
367 // If one side has only a king, check whether exists any unstoppable passed pawn
368 if (!pos.non_pawn_material(WHITE) || !pos.non_pawn_material(BLACK))
369 score += evaluate_unstoppable_pawns(pos, ei);
371 // Evaluate space for both sides, only in middle-game.
372 if (ei.mi->space_weight())
374 int s = evaluate_space<WHITE>(pos, ei) - evaluate_space<BLACK>(pos, ei);
375 score += apply_weight(s * ei.mi->space_weight(), Weights[Space]);
378 // Scale winning side if position is more drawish that what it appears
379 ScaleFactor sf = eg_value(score) > VALUE_DRAW ? ei.mi->scale_factor(pos, WHITE)
380 : ei.mi->scale_factor(pos, BLACK);
382 // If we don't already have an unusual scale factor, check for opposite
383 // colored bishop endgames, and use a lower scale for those.
384 if ( ei.mi->game_phase() < PHASE_MIDGAME
385 && pos.opposite_bishops()
386 && sf == SCALE_FACTOR_NORMAL)
388 // Only the two bishops ?
389 if ( pos.non_pawn_material(WHITE) == BishopValueMg
390 && pos.non_pawn_material(BLACK) == BishopValueMg)
392 // Check for KBP vs KB with only a single pawn that is almost
393 // certainly a draw or at least two pawns.
394 bool one_pawn = (pos.count<PAWN>(WHITE) + pos.count<PAWN>(BLACK) == 1);
395 sf = one_pawn ? ScaleFactor(8) : ScaleFactor(32);
398 // Endgame with opposite-colored bishops, but also other pieces. Still
399 // a bit drawish, but not as drawish as with only the two bishops.
400 sf = ScaleFactor(50);
403 margin = margins[pos.side_to_move()];
404 Value v = interpolate(score, ei.mi->game_phase(), sf);
406 // In case of tracing add all single evaluation contributions for both white and black
409 Tracing::add(PST, pos.psq_score());
410 Tracing::add(IMBALANCE, ei.mi->material_value());
411 Tracing::add(PAWN, ei.pi->pawns_value());
412 Tracing::add(UNSTOPPABLE, evaluate_unstoppable_pawns(pos, ei));
413 Score w = ei.mi->space_weight() * evaluate_space<WHITE>(pos, ei);
414 Score b = ei.mi->space_weight() * evaluate_space<BLACK>(pos, ei);
415 Tracing::add(SPACE, apply_weight(w, Weights[Space]), apply_weight(b, Weights[Space]));
416 Tracing::add(TOTAL, score);
417 Tracing::stream << "\nUncertainty margin: White: " << to_cp(margins[WHITE])
418 << ", Black: " << to_cp(margins[BLACK])
419 << "\nScaling: " << std::noshowpos
420 << std::setw(6) << 100.0 * ei.mi->game_phase() / 128.0 << "% MG, "
421 << std::setw(6) << 100.0 * (1.0 - ei.mi->game_phase() / 128.0) << "% * "
422 << std::setw(6) << (100.0 * sf) / SCALE_FACTOR_NORMAL << "% EG.\n"
423 << "Total evaluation: " << to_cp(v);
426 return pos.side_to_move() == WHITE ? v : -v;
430 // init_eval_info() initializes king bitboards for given color adding
431 // pawn attacks. To be done at the beginning of the evaluation.
434 void init_eval_info(const Position& pos, EvalInfo& ei) {
436 const Color Them = (Us == WHITE ? BLACK : WHITE);
437 const Square Down = (Us == WHITE ? DELTA_S : DELTA_N);
439 Bitboard b = ei.attackedBy[Them][KING] = pos.attacks_from<KING>(pos.king_square(Them));
440 ei.attackedBy[Us][PAWN] = ei.pi->pawn_attacks(Us);
442 // Init king safety tables only if we are going to use them
443 if (pos.count<QUEEN>(Us) && pos.non_pawn_material(Us) > QueenValueMg + PawnValueMg)
445 ei.kingRing[Them] = b | shift_bb<Down>(b);
446 b &= ei.attackedBy[Us][PAWN];
447 ei.kingAttackersCount[Us] = b ? popcount<Max15>(b) / 2 : 0;
448 ei.kingAdjacentZoneAttacksCount[Us] = ei.kingAttackersWeight[Us] = 0;
450 ei.kingRing[Them] = ei.kingAttackersCount[Us] = 0;
454 // evaluate_outposts() evaluates bishop and knight outposts squares
456 template<PieceType Piece, Color Us>
457 Score evaluate_outposts(const Position& pos, EvalInfo& ei, Square s) {
459 const Color Them = (Us == WHITE ? BLACK : WHITE);
461 assert (Piece == BISHOP || Piece == KNIGHT);
463 // Initial bonus based on square
464 Value bonus = Outpost[Piece == BISHOP][relative_square(Us, s)];
466 // Increase bonus if supported by pawn, especially if the opponent has
467 // no minor piece which can exchange the outpost piece.
468 if (bonus && (ei.attackedBy[Us][PAWN] & s))
470 if ( !pos.pieces(Them, KNIGHT)
471 && !(squares_of_color(s) & pos.pieces(Them, BISHOP)))
472 bonus += bonus + bonus / 2;
476 return make_score(bonus, bonus);
480 // evaluate_pieces<>() assigns bonuses and penalties to the pieces of a given color
482 template<PieceType Piece, Color Us, bool Trace>
483 Score evaluate_pieces(const Position& pos, EvalInfo& ei, Score& mobility, Bitboard mobilityArea) {
487 Score score = SCORE_ZERO;
489 const Color Them = (Us == WHITE ? BLACK : WHITE);
490 const Square* pl = pos.list<Piece>(Us);
492 ei.attackedBy[Us][Piece] = 0;
494 while ((s = *pl++) != SQ_NONE)
496 // Find attacked squares, including x-ray attacks for bishops and rooks
497 b = Piece == BISHOP ? attacks_bb<BISHOP>(s, pos.pieces() ^ pos.pieces(Us, QUEEN))
498 : Piece == ROOK ? attacks_bb< ROOK>(s, pos.pieces() ^ pos.pieces(Us, ROOK, QUEEN))
499 : pos.attacks_from<Piece>(s);
501 ei.attackedBy[Us][Piece] |= b;
503 if (b & ei.kingRing[Them])
505 ei.kingAttackersCount[Us]++;
506 ei.kingAttackersWeight[Us] += KingAttackWeights[Piece];
507 Bitboard bb = (b & ei.attackedBy[Them][KING]);
509 ei.kingAdjacentZoneAttacksCount[Us] += popcount<Max15>(bb);
512 int mob = Piece != QUEEN ? popcount<Max15>(b & mobilityArea)
513 : popcount<Full >(b & mobilityArea);
515 mobility += MobilityBonus[Piece][mob];
517 // Decrease score if we are attacked by an enemy pawn. Remaining part
518 // of threat evaluation must be done later when we have full attack info.
519 if (ei.attackedBy[Them][PAWN] & s)
520 score -= ThreatenedByPawn[Piece];
522 // Otherwise give a bonus if we are a bishop and can pin a piece or can
523 // give a discovered check through an x-ray attack.
524 else if ( Piece == BISHOP
525 && (PseudoAttacks[Piece][pos.king_square(Them)] & s)
526 && !more_than_one(BetweenBB[s][pos.king_square(Them)] & pos.pieces()))
529 // Penalty for bishop with same coloured pawns
531 score -= BishopPawns * ei.pi->pawns_on_same_color_squares(Us, s);
533 if (Piece == BISHOP || Piece == KNIGHT)
535 // Bishop and knight outposts squares
536 if (!(pos.pieces(Them, PAWN) & pawn_attack_span(Us, s)))
537 score += evaluate_outposts<Piece, Us>(pos, ei, s);
539 // Bishop or knight behind a pawn
540 if ( relative_rank(Us, s) < RANK_5
541 && (pos.pieces(PAWN) & (s + pawn_push(Us))))
542 score += MinorBehindPawn;
545 if ( (Piece == ROOK || Piece == QUEEN)
546 && relative_rank(Us, s) >= RANK_5)
548 // Major piece on 7th rank and enemy king trapped on 8th
549 if ( relative_rank(Us, s) == RANK_7
550 && relative_rank(Us, pos.king_square(Them)) == RANK_8)
551 score += Piece == ROOK ? RookOn7th : QueenOn7th;
553 // Major piece attacking enemy pawns on the same rank/file
554 Bitboard pawns = pos.pieces(Them, PAWN) & PseudoAttacks[ROOK][s];
556 score += popcount<Max15>(pawns) * (Piece == ROOK ? RookOnPawn : QueenOnPawn);
559 // Special extra evaluation for rooks
562 // Give a bonus for a rook on a open or semi-open file
563 if (ei.pi->semiopen(Us, file_of(s)))
564 score += ei.pi->semiopen(Them, file_of(s)) ? RookOpenFile : RookSemiopenFile;
566 if (mob > 3 || ei.pi->semiopen(Us, file_of(s)))
569 Square ksq = pos.king_square(Us);
571 // Penalize rooks which are trapped inside a king. Penalize more if
572 // king has lost right to castle.
573 if ( ((file_of(ksq) < FILE_E) == (file_of(s) < file_of(ksq)))
574 && (rank_of(ksq) == rank_of(s) || relative_rank(Us, ksq) == RANK_1)
575 && !ei.pi->semiopen_on_side(Us, file_of(ksq), file_of(ksq) < FILE_E))
576 score -= (TrappedRook - make_score(mob * 8, 0)) * (pos.can_castle(Us) ? 1 : 2);
579 // An important Chess960 pattern: A cornered bishop blocked by a friendly
580 // pawn diagonally in front of it is a very serious problem, especially
581 // when that pawn is also blocked.
584 && (s == relative_square(Us, SQ_A1) || s == relative_square(Us, SQ_H1)))
586 const enum Piece P = make_piece(Us, PAWN);
587 Square d = pawn_push(Us) + (file_of(s) == FILE_A ? DELTA_E : DELTA_W);
588 if (pos.piece_on(s + d) == P)
589 score -= !pos.is_empty(s + d + pawn_push(Us)) ? TrappedBishopA1H1 * 4
590 : pos.piece_on(s + d + d) == P ? TrappedBishopA1H1 * 2
596 Tracing::scores[Us][Piece] = score;
602 // evaluate_threats<>() assigns bonuses according to the type of attacking piece
603 // and the type of attacked one.
605 template<Color Us, bool Trace>
606 Score evaluate_threats(const Position& pos, const EvalInfo& ei) {
608 const Color Them = (Us == WHITE ? BLACK : WHITE);
610 Bitboard b, undefendedMinors, weakEnemies;
611 Score score = SCORE_ZERO;
613 // Undefended minors get penalized even if not under attack
614 undefendedMinors = pos.pieces(Them, BISHOP, KNIGHT)
615 & ~ei.attackedBy[Them][ALL_PIECES];
617 if (undefendedMinors)
618 score += UndefendedMinor;
620 // Enemy pieces not defended by a pawn and under our attack
621 weakEnemies = pos.pieces(Them)
622 & ~ei.attackedBy[Them][PAWN]
623 & ei.attackedBy[Us][ALL_PIECES];
625 // Add bonus according to type of attacked enemy piece and to the
626 // type of attacking piece, from knights to queens. Kings are not
627 // considered because are already handled in king evaluation.
629 for (PieceType pt1 = KNIGHT; pt1 < KING; pt1++)
631 b = ei.attackedBy[Us][pt1] & weakEnemies;
633 for (PieceType pt2 = PAWN; pt2 < KING; pt2++)
634 if (b & pos.pieces(pt2))
635 score += Threat[pt1][pt2];
639 Tracing::scores[Us][THREAT] = score;
645 // evaluate_pieces_of_color<>() assigns bonuses and penalties to all the
646 // pieces of a given color.
648 template<Color Us, bool Trace>
649 Score evaluate_pieces_of_color(const Position& pos, EvalInfo& ei, Score& mobility) {
651 const Color Them = (Us == WHITE ? BLACK : WHITE);
653 Score score = mobility = SCORE_ZERO;
655 // Do not include in mobility squares protected by enemy pawns or occupied by our pieces
656 const Bitboard mobilityArea = ~(ei.attackedBy[Them][PAWN] | pos.pieces(Us, PAWN, KING));
658 score += evaluate_pieces<KNIGHT, Us, Trace>(pos, ei, mobility, mobilityArea);
659 score += evaluate_pieces<BISHOP, Us, Trace>(pos, ei, mobility, mobilityArea);
660 score += evaluate_pieces<ROOK, Us, Trace>(pos, ei, mobility, mobilityArea);
661 score += evaluate_pieces<QUEEN, Us, Trace>(pos, ei, mobility, mobilityArea);
663 // Sum up all attacked squares
664 ei.attackedBy[Us][ALL_PIECES] = ei.attackedBy[Us][PAWN] | ei.attackedBy[Us][KNIGHT]
665 | ei.attackedBy[Us][BISHOP] | ei.attackedBy[Us][ROOK]
666 | ei.attackedBy[Us][QUEEN] | ei.attackedBy[Us][KING];
668 Tracing::scores[Us][MOBILITY] = apply_weight(mobility, Weights[Mobility]);
674 // evaluate_king<>() assigns bonuses and penalties to a king of a given color
676 template<Color Us, bool Trace>
677 Score evaluate_king(const Position& pos, const EvalInfo& ei, Value margins[]) {
679 const Color Them = (Us == WHITE ? BLACK : WHITE);
681 Bitboard undefended, b, b1, b2, safe;
683 const Square ksq = pos.king_square(Us);
685 // King shelter and enemy pawns storm
686 Score score = ei.pi->king_safety<Us>(pos, ksq);
688 // King safety. This is quite complicated, and is almost certainly far
689 // from optimally tuned.
690 if ( ei.kingAttackersCount[Them] >= 2
691 && ei.kingAdjacentZoneAttacksCount[Them])
693 // Find the attacked squares around the king which has no defenders
694 // apart from the king itself
695 undefended = ei.attackedBy[Them][ALL_PIECES] & ei.attackedBy[Us][KING];
696 undefended &= ~( ei.attackedBy[Us][PAWN] | ei.attackedBy[Us][KNIGHT]
697 | ei.attackedBy[Us][BISHOP] | ei.attackedBy[Us][ROOK]
698 | ei.attackedBy[Us][QUEEN]);
700 // Initialize the 'attackUnits' variable, which is used later on as an
701 // index to the KingDanger[] array. The initial value is based on the
702 // number and types of the enemy's attacking pieces, the number of
703 // attacked and undefended squares around our king, the square of the
704 // king, and the quality of the pawn shelter.
705 attackUnits = std::min(25, (ei.kingAttackersCount[Them] * ei.kingAttackersWeight[Them]) / 2)
706 + 3 * (ei.kingAdjacentZoneAttacksCount[Them] + popcount<Max15>(undefended))
707 + KingExposed[relative_square(Us, ksq)]
708 - mg_value(score) / 32;
710 // Analyse enemy's safe queen contact checks. First find undefended
711 // squares around the king attacked by enemy queen...
712 b = undefended & ei.attackedBy[Them][QUEEN] & ~pos.pieces(Them);
715 // ...then remove squares not supported by another enemy piece
716 b &= ( ei.attackedBy[Them][PAWN] | ei.attackedBy[Them][KNIGHT]
717 | ei.attackedBy[Them][BISHOP] | ei.attackedBy[Them][ROOK]);
719 attackUnits += QueenContactCheck
721 * (Them == pos.side_to_move() ? 2 : 1);
724 // Analyse enemy's safe rook contact checks. First find undefended
725 // squares around the king attacked by enemy rooks...
726 b = undefended & ei.attackedBy[Them][ROOK] & ~pos.pieces(Them);
728 // Consider only squares where the enemy rook gives check
729 b &= PseudoAttacks[ROOK][ksq];
733 // ...then remove squares not supported by another enemy piece
734 b &= ( ei.attackedBy[Them][PAWN] | ei.attackedBy[Them][KNIGHT]
735 | ei.attackedBy[Them][BISHOP] | ei.attackedBy[Them][QUEEN]);
737 attackUnits += RookContactCheck
739 * (Them == pos.side_to_move() ? 2 : 1);
742 // Analyse enemy's safe distance checks for sliders and knights
743 safe = ~(pos.pieces(Them) | ei.attackedBy[Us][ALL_PIECES]);
745 b1 = pos.attacks_from<ROOK>(ksq) & safe;
746 b2 = pos.attacks_from<BISHOP>(ksq) & safe;
748 // Enemy queen safe checks
749 b = (b1 | b2) & ei.attackedBy[Them][QUEEN];
751 attackUnits += QueenCheck * popcount<Max15>(b);
753 // Enemy rooks safe checks
754 b = b1 & ei.attackedBy[Them][ROOK];
756 attackUnits += RookCheck * popcount<Max15>(b);
758 // Enemy bishops safe checks
759 b = b2 & ei.attackedBy[Them][BISHOP];
761 attackUnits += BishopCheck * popcount<Max15>(b);
763 // Enemy knights safe checks
764 b = pos.attacks_from<KNIGHT>(ksq) & ei.attackedBy[Them][KNIGHT] & safe;
766 attackUnits += KnightCheck * popcount<Max15>(b);
768 // To index KingDanger[] attackUnits must be in [0, 99] range
769 attackUnits = std::min(99, std::max(0, attackUnits));
771 // Finally, extract the king danger score from the KingDanger[]
772 // array and subtract the score from evaluation. Set also margins[]
773 // value that will be used for pruning because this value can sometimes
774 // be very big, and so capturing a single attacking piece can therefore
775 // result in a score change far bigger than the value of the captured piece.
776 score -= KingDanger[Us == Search::RootColor][attackUnits];
777 margins[Us] += mg_value(KingDanger[Us == Search::RootColor][attackUnits]);
781 Tracing::scores[Us][KING] = score;
787 // evaluate_passed_pawns<>() evaluates the passed pawns of the given color
789 template<Color Us, bool Trace>
790 Score evaluate_passed_pawns(const Position& pos, const EvalInfo& ei) {
792 const Color Them = (Us == WHITE ? BLACK : WHITE);
794 Bitboard b, squaresToQueen, defendedSquares, unsafeSquares, supportingPawns;
795 Score score = SCORE_ZERO;
797 b = ei.pi->passed_pawns(Us);
801 Square s = pop_lsb(&b);
803 assert(pos.pawn_is_passed(Us, s));
805 int r = int(relative_rank(Us, s) - RANK_2);
806 int rr = r * (r - 1);
808 // Base bonus based on rank
809 Value mbonus = Value(17 * rr);
810 Value ebonus = Value(7 * (rr + r + 1));
814 Square blockSq = s + pawn_push(Us);
816 // Adjust bonus based on kings proximity
817 ebonus += Value(square_distance(pos.king_square(Them), blockSq) * 5 * rr);
818 ebonus -= Value(square_distance(pos.king_square(Us), blockSq) * 2 * rr);
820 // If blockSq is not the queening square then consider also a second push
821 if (rank_of(blockSq) != (Us == WHITE ? RANK_8 : RANK_1))
822 ebonus -= Value(square_distance(pos.king_square(Us), blockSq + pawn_push(Us)) * rr);
824 // If the pawn is free to advance, increase bonus
825 if (pos.is_empty(blockSq))
827 squaresToQueen = forward_bb(Us, s);
829 // If there is an enemy rook or queen attacking the pawn from behind,
830 // add all X-ray attacks by the rook or queen. Otherwise consider only
831 // the squares in the pawn's path attacked or occupied by the enemy.
832 if ( unlikely(forward_bb(Them, s) & pos.pieces(Them, ROOK, QUEEN))
833 && (forward_bb(Them, s) & pos.pieces(Them, ROOK, QUEEN) & pos.attacks_from<ROOK>(s)))
834 unsafeSquares = squaresToQueen;
836 unsafeSquares = squaresToQueen & (ei.attackedBy[Them][ALL_PIECES] | pos.pieces(Them));
838 if ( unlikely(forward_bb(Them, s) & pos.pieces(Us, ROOK, QUEEN))
839 && (forward_bb(Them, s) & pos.pieces(Us, ROOK, QUEEN) & pos.attacks_from<ROOK>(s)))
840 defendedSquares = squaresToQueen;
842 defendedSquares = squaresToQueen & ei.attackedBy[Us][ALL_PIECES];
844 // If there aren't enemy attacks huge bonus, a bit smaller if at
845 // least block square is not attacked, otherwise smallest bonus.
846 int k = !unsafeSquares ? 15 : !(unsafeSquares & blockSq) ? 9 : 3;
848 // Big bonus if the path to queen is fully defended, a bit less
849 // if at least block square is defended.
850 if (defendedSquares == squaresToQueen)
853 else if (defendedSquares & blockSq)
854 k += (unsafeSquares & defendedSquares) == unsafeSquares ? 4 : 2;
856 mbonus += Value(k * rr), ebonus += Value(k * rr);
860 // Increase the bonus if the passed pawn is supported by a friendly pawn
861 // on the same rank and a bit smaller if it's on the previous rank.
862 supportingPawns = pos.pieces(Us, PAWN) & adjacent_files_bb(file_of(s));
863 if (supportingPawns & rank_bb(s))
864 ebonus += Value(r * 20);
866 else if (supportingPawns & rank_bb(s - pawn_push(Us)))
867 ebonus += Value(r * 12);
869 // Rook pawns are a special case: They are sometimes worse, and
870 // sometimes better than other passed pawns. It is difficult to find
871 // good rules for determining whether they are good or bad. For now,
872 // we try the following: Increase the value for rook pawns if the
873 // other side has no pieces apart from a knight, and decrease the
874 // value if the other side has a rook or queen.
875 if (file_of(s) == FILE_A || file_of(s) == FILE_H)
877 if (pos.non_pawn_material(Them) <= KnightValueMg)
878 ebonus += ebonus / 4;
879 else if (pos.pieces(Them, ROOK, QUEEN))
880 ebonus -= ebonus / 4;
882 score += make_score(mbonus, ebonus);
887 Tracing::scores[Us][PASSED] = apply_weight(score, Weights[PassedPawns]);
889 // Add the scores to the middle game and endgame eval
890 return apply_weight(score, Weights[PassedPawns]);
894 // evaluate_unstoppable_pawns() evaluates the unstoppable passed pawns for both sides, this is quite
895 // conservative and returns a winning score only when we are very sure that the pawn is winning.
897 Score evaluate_unstoppable_pawns(const Position& pos, const EvalInfo& ei) {
899 Bitboard b, b2, blockers, supporters, queeningPath, candidates;
900 Square s, blockSq, queeningSquare;
901 Color c, winnerSide, loserSide;
902 bool pathDefended, opposed;
903 int pliesToGo, movesToGo, oppMovesToGo, sacptg, blockersCount, minKingDist, kingptg, d;
904 int pliesToQueen[] = { 256, 256 };
906 // Step 1. Hunt for unstoppable passed pawns. If we find at least one,
907 // record how many plies are required for promotion.
908 for (c = WHITE; c <= BLACK; c++)
910 // Skip if other side has non-pawn pieces
911 if (pos.non_pawn_material(~c))
914 b = ei.pi->passed_pawns(c);
919 queeningSquare = relative_square(c, file_of(s) | RANK_8);
920 queeningPath = forward_bb(c, s);
922 // Compute plies to queening and check direct advancement
923 movesToGo = rank_distance(s, queeningSquare) - int(relative_rank(c, s) == RANK_2);
924 oppMovesToGo = square_distance(pos.king_square(~c), queeningSquare) - int(c != pos.side_to_move());
925 pathDefended = ((ei.attackedBy[c][ALL_PIECES] & queeningPath) == queeningPath);
927 if (movesToGo >= oppMovesToGo && !pathDefended)
930 // Opponent king cannot block because path is defended and position
931 // is not in check. So only friendly pieces can be blockers.
932 assert(!pos.checkers());
933 assert((queeningPath & pos.pieces()) == (queeningPath & pos.pieces(c)));
935 // Add moves needed to free the path from friendly pieces and retest condition
936 movesToGo += popcount<Max15>(queeningPath & pos.pieces(c));
938 if (movesToGo >= oppMovesToGo && !pathDefended)
941 pliesToGo = 2 * movesToGo - int(c == pos.side_to_move());
942 pliesToQueen[c] = std::min(pliesToQueen[c], pliesToGo);
946 // Step 2. If either side cannot promote at least three plies before the other side then situation
947 // becomes too complex and we give up. Otherwise we determine the possibly "winning side"
948 if (abs(pliesToQueen[WHITE] - pliesToQueen[BLACK]) < 3)
951 winnerSide = (pliesToQueen[WHITE] < pliesToQueen[BLACK] ? WHITE : BLACK);
952 loserSide = ~winnerSide;
954 // Step 3. Can the losing side possibly create a new passed pawn and thus prevent the loss?
955 b = candidates = pos.pieces(loserSide, PAWN);
961 // Compute plies from queening
962 queeningSquare = relative_square(loserSide, file_of(s) | RANK_8);
963 movesToGo = rank_distance(s, queeningSquare) - int(relative_rank(loserSide, s) == RANK_2);
964 pliesToGo = 2 * movesToGo - int(loserSide == pos.side_to_move());
966 // Check if (without even considering any obstacles) we're too far away or doubled
967 if ( pliesToQueen[winnerSide] + 3 <= pliesToGo
968 || (forward_bb(loserSide, s) & pos.pieces(loserSide, PAWN)))
972 // If any candidate is already a passed pawn it _may_ promote in time. We give up.
973 if (candidates & ei.pi->passed_pawns(loserSide))
976 // Step 4. Check new passed pawn creation through king capturing and pawn sacrifices
982 sacptg = blockersCount = 0;
983 minKingDist = kingptg = 256;
985 // Compute plies from queening
986 queeningSquare = relative_square(loserSide, file_of(s) | RANK_8);
987 movesToGo = rank_distance(s, queeningSquare) - int(relative_rank(loserSide, s) == RANK_2);
988 pliesToGo = 2 * movesToGo - int(loserSide == pos.side_to_move());
990 // Generate list of blocking pawns and supporters
991 supporters = adjacent_files_bb(file_of(s)) & candidates;
992 opposed = forward_bb(loserSide, s) & pos.pieces(winnerSide, PAWN);
993 blockers = passed_pawn_mask(loserSide, s) & pos.pieces(winnerSide, PAWN);
997 // How many plies does it take to remove all the blocking pawns?
1000 blockSq = pop_lsb(&blockers);
1003 // Check pawns that can give support to overcome obstacle, for instance
1004 // black pawns: a4, b4 white: b2 then pawn in b4 is giving support.
1007 b2 = supporters & in_front_bb(winnerSide, rank_of(blockSq + pawn_push(winnerSide)));
1009 while (b2) // This while-loop could be replaced with LSB/MSB (depending on color)
1011 d = square_distance(blockSq, pop_lsb(&b2)) - 2;
1012 movesToGo = std::min(movesToGo, d);
1016 // Check pawns that can be sacrificed against the blocking pawn
1017 b2 = pawn_attack_span(winnerSide, blockSq) & candidates & ~(1ULL << s);
1019 while (b2) // This while-loop could be replaced with LSB/MSB (depending on color)
1021 d = square_distance(blockSq, pop_lsb(&b2)) - 2;
1022 movesToGo = std::min(movesToGo, d);
1025 // If obstacle can be destroyed with an immediate pawn exchange / sacrifice,
1026 // it's not a real obstacle and we have nothing to add to pliesToGo.
1030 // Plies needed to sacrifice against all the blocking pawns
1031 sacptg += movesToGo * 2;
1034 // Plies needed for the king to capture all the blocking pawns
1035 d = square_distance(pos.king_square(loserSide), blockSq);
1036 minKingDist = std::min(minKingDist, d);
1037 kingptg = (minKingDist + blockersCount) * 2;
1040 // Check if pawn sacrifice plan _may_ save the day
1041 if (pliesToQueen[winnerSide] + 3 > pliesToGo + sacptg)
1044 // Check if king capture plan _may_ save the day (contains some false positives)
1045 if (pliesToQueen[winnerSide] + 3 > pliesToGo + kingptg)
1049 // Winning pawn is unstoppable and will promote as first, return big score
1050 Score score = make_score(0, (Value) 1280 - 32 * pliesToQueen[winnerSide]);
1051 return winnerSide == WHITE ? score : -score;
1055 // evaluate_space() computes the space evaluation for a given side. The
1056 // space evaluation is a simple bonus based on the number of safe squares
1057 // available for minor pieces on the central four files on ranks 2--4. Safe
1058 // squares one, two or three squares behind a friendly pawn are counted
1059 // twice. Finally, the space bonus is scaled by a weight taken from the
1060 // material hash table. The aim is to improve play on game opening.
1062 int evaluate_space(const Position& pos, const EvalInfo& ei) {
1064 const Color Them = (Us == WHITE ? BLACK : WHITE);
1066 // Find the safe squares for our pieces inside the area defined by
1067 // SpaceMask[]. A square is unsafe if it is attacked by an enemy
1068 // pawn, or if it is undefended and attacked by an enemy piece.
1069 Bitboard safe = SpaceMask[Us]
1070 & ~pos.pieces(Us, PAWN)
1071 & ~ei.attackedBy[Them][PAWN]
1072 & (ei.attackedBy[Us][ALL_PIECES] | ~ei.attackedBy[Them][ALL_PIECES]);
1074 // Find all squares which are at most three squares behind some friendly pawn
1075 Bitboard behind = pos.pieces(Us, PAWN);
1076 behind |= (Us == WHITE ? behind >> 8 : behind << 8);
1077 behind |= (Us == WHITE ? behind >> 16 : behind << 16);
1079 // Since SpaceMask[Us] is fully on our half of the board
1080 assert(unsigned(safe >> (Us == WHITE ? 32 : 0)) == 0);
1082 // Count safe + (behind & safe) with a single popcount
1083 return popcount<Full>((Us == WHITE ? safe << 32 : safe >> 32) | (behind & safe));
1087 // interpolate() interpolates between a middle game and an endgame score,
1088 // based on game phase. It also scales the return value by a ScaleFactor array.
1090 Value interpolate(const Score& v, Phase ph, ScaleFactor sf) {
1092 assert(mg_value(v) > -VALUE_INFINITE && mg_value(v) < VALUE_INFINITE);
1093 assert(eg_value(v) > -VALUE_INFINITE && eg_value(v) < VALUE_INFINITE);
1094 assert(ph >= PHASE_ENDGAME && ph <= PHASE_MIDGAME);
1096 int e = (eg_value(v) * int(sf)) / SCALE_FACTOR_NORMAL;
1097 int r = (mg_value(v) * int(ph) + e * int(PHASE_MIDGAME - ph)) / PHASE_MIDGAME;
1098 return Value((r / GrainSize) * GrainSize); // Sign independent
1101 // apply_weight() weights score v by score w trying to prevent overflow
1102 Score apply_weight(Score v, Score w) {
1103 return make_score((int(mg_value(v)) * mg_value(w)) / 0x100,
1104 (int(eg_value(v)) * eg_value(w)) / 0x100);
1107 // weight_option() computes the value of an evaluation weight, by combining
1108 // two UCI-configurable weights (midgame and endgame) with an internal weight.
1110 Score weight_option(const std::string& mgOpt, const std::string& egOpt, Score internalWeight) {
1112 // Scale option value from 100 to 256
1113 int mg = Options[mgOpt] * 256 / 100;
1114 int eg = Options[egOpt] * 256 / 100;
1116 return apply_weight(make_score(mg, eg), internalWeight);
1120 // Tracing functions definitions
1122 double to_cp(Value v) { return double(v) / double(PawnValueMg); }
1124 void Tracing::add(int idx, Score wScore, Score bScore) {
1126 scores[WHITE][idx] = wScore;
1127 scores[BLACK][idx] = bScore;
1130 void Tracing::row(const char* name, int idx) {
1132 Score wScore = scores[WHITE][idx];
1133 Score bScore = scores[BLACK][idx];
1136 case PST: case IMBALANCE: case PAWN: case UNSTOPPABLE: case TOTAL:
1137 stream << std::setw(20) << name << " | --- --- | --- --- | "
1138 << std::setw(6) << to_cp(mg_value(wScore)) << " "
1139 << std::setw(6) << to_cp(eg_value(wScore)) << " \n";
1142 stream << std::setw(20) << name << " | " << std::noshowpos
1143 << std::setw(5) << to_cp(mg_value(wScore)) << " "
1144 << std::setw(5) << to_cp(eg_value(wScore)) << " | "
1145 << std::setw(5) << to_cp(mg_value(bScore)) << " "
1146 << std::setw(5) << to_cp(eg_value(bScore)) << " | "
1148 << std::setw(6) << to_cp(mg_value(wScore - bScore)) << " "
1149 << std::setw(6) << to_cp(eg_value(wScore - bScore)) << " \n";
1153 std::string Tracing::do_trace(const Position& pos) {
1156 stream << std::showpoint << std::showpos << std::fixed << std::setprecision(2);
1157 std::memset(scores, 0, 2 * (TOTAL + 1) * sizeof(Score));
1160 do_evaluate<true>(pos, margin);
1162 std::string totals = stream.str();
1165 stream << std::setw(21) << "Eval term " << "| White | Black | Total \n"
1166 << " | MG EG | MG EG | MG EG \n"
1167 << "---------------------+-------------+-------------+---------------\n";
1169 row("Material, PST, Tempo", PST);
1170 row("Material imbalance", IMBALANCE);
1172 row("Knights", KNIGHT);
1173 row("Bishops", BISHOP);
1175 row("Queens", QUEEN);
1176 row("Mobility", MOBILITY);
1177 row("King safety", KING);
1178 row("Threats", THREAT);
1179 row("Passed pawns", PASSED);
1180 row("Unstoppable pawns", UNSTOPPABLE);
1181 row("Space", SPACE);
1183 stream << "---------------------+-------------+-------------+---------------\n";
1184 row("Total", TOTAL);
1187 return stream.str();