/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
- Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008 Marco Costalba
+ Copyright (C) 2004-2023 The Stockfish developers (see AUTHORS file)
Stockfish is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
-
-#if !defined(ENDGAME_H_INCLUDED)
+#ifndef ENDGAME_H_INCLUDED
#define ENDGAME_H_INCLUDED
-////
-//// Includes
-////
+#include <memory>
+#include <string>
+#include <type_traits>
+#include <unordered_map>
+#include <utility>
#include "position.h"
-#include "scale.h"
-#include "value.h"
-
-
-////
-//// Types
-////
-
-/// Abstract base class for all special endgame evaluation functions
-
-class EndgameEvaluationFunction {
-public:
- EndgameEvaluationFunction(Color c);
- virtual ~EndgameEvaluationFunction() { }
-
- virtual Value apply(const Position &pos) = 0;
-
-protected:
- Color strongerSide, weakerSide;
-};
-
-
-/// Template subclass for various concrete endgames
-
-enum EndgameType {
- KXK, // Generic "mate lone king" eval
- KBNK, // KBN vs K
- KPK, // KP vs K
- KRKP, // KR vs KP
- KRKB, // KR vs KB
- KRKN, // KR vs KN
- KQKR, // KQ vs KR
- KBBKN, // KBB vs KN
- KmmKm // K and two minors vs K and one or two minors
-};
-
-template<EndgameType>
-class EvaluationFunction : public EndgameEvaluationFunction {
-public:
- explicit EvaluationFunction(Color c): EndgameEvaluationFunction(c) {}
- Value apply(const Position& pos);
-};
-
-/// Abstract base class for all evaluation scaling functions:
-
-class ScalingFunction {
-public:
- ScalingFunction(Color c);
- virtual ~ScalingFunction() { }
-
- virtual ScaleFactor apply(const Position &pos) =0;
-
-protected:
- Color strongerSide, weakerSide;
+#include "types.h"
+
+namespace Stockfish {
+
+/// EndgameCode lists all supported endgame functions by corresponding codes
+
+enum EndgameCode {
+
+ EVALUATION_FUNCTIONS,
+ KNNK, // KNN vs K
+ KNNKP, // KNN vs KP
+ KXK, // Generic "mate lone king" eval
+ KBNK, // KBN vs K
+ KPK, // KP vs K
+ KRKP, // KR vs KP
+ KRKB, // KR vs KB
+ KRKN, // KR vs KN
+ KQKP, // KQ vs KP
+ KQKR, // KQ vs KR
+
+ SCALING_FUNCTIONS,
+ KBPsK, // KB and pawns vs K
+ KQKRPs, // KQ vs KR and pawns
+ KRPKR, // KRP vs KR
+ KRPKB, // KRP vs KB
+ KRPPKRP, // KRPP vs KRP
+ KPsK, // K and pawns vs K
+ KBPKB, // KBP vs KB
+ KBPPKB, // KBPP vs KB
+ KBPKN, // KBP vs KN
+ KPKP // KP vs KP
};
-/// Subclasses for various concrete endgames:
+/// Endgame functions can be of two types depending on whether they return a
+/// Value or a ScaleFactor.
-// KBP vs K:
-class KBPKScalingFunction : public ScalingFunction {
-public:
- KBPKScalingFunction(Color c);
- ScaleFactor apply(const Position &pos);
-};
+template<EndgameCode E> using
+eg_type = typename std::conditional<(E < SCALING_FUNCTIONS), Value, ScaleFactor>::type;
-// KQ vs KRP:
-class KQKRPScalingFunction: public ScalingFunction {
-public:
- KQKRPScalingFunction(Color c);
- ScaleFactor apply(const Position &pos);
-};
-// KRP vs KR:
-class KRPKRScalingFunction : public ScalingFunction {
-public:
- KRPKRScalingFunction(Color c);
- ScaleFactor apply(const Position &pos);
-};
+/// Base and derived functors for endgame evaluation and scaling functions
-// KRPP vs KRP:
-class KRPPKRPScalingFunction : public ScalingFunction {
-public:
- KRPPKRPScalingFunction(Color c);
- ScaleFactor apply(const Position &pos);
-};
+template<typename T>
+struct EndgameBase {
-// King and pawns vs king:
-class KPsKScalingFunction : public ScalingFunction {
-public:
- KPsKScalingFunction(Color c);
- ScaleFactor apply(const Position &pos);
-};
+ explicit EndgameBase(Color c) : strongSide(c), weakSide(~c) {}
+ virtual ~EndgameBase() = default;
+ virtual T operator()(const Position&) const = 0;
-// KBP vs KB:
-class KBPKBScalingFunction : public ScalingFunction {
-public:
- KBPKBScalingFunction(Color c);
- ScaleFactor apply(const Position &pos);
+ const Color strongSide, weakSide;
};
-// KBP vs KN:
-class KBPKNScalingFunction : public ScalingFunction {
-public:
- KBPKNScalingFunction(Color c);
- ScaleFactor apply(const Position &pos);
-};
-// KNP vs K:
-class KNPKScalingFunction : public ScalingFunction {
-public:
- KNPKScalingFunction(Color c);
- ScaleFactor apply(const Position &pos);
-};
+template<EndgameCode E, typename T = eg_type<E>>
+struct Endgame : public EndgameBase<T> {
-// KP vs KP:
-class KPKPScalingFunction : public ScalingFunction {
-public:
- KPKPScalingFunction(Color c);
- ScaleFactor apply(const Position &pos);
+ explicit Endgame(Color c) : EndgameBase<T>(c) {}
+ T operator()(const Position&) const override;
};
-////
-//// Constants and variables
-////
-
-extern EvaluationFunction<KXK> EvaluateKXK, EvaluateKKX; // Generic "mate lone king" eval
-extern EvaluationFunction<KBNK> EvaluateKBNK, EvaluateKKBN; // KBN vs K
-extern EvaluationFunction<KPK> EvaluateKPK, EvaluateKKP; // KP vs K
-extern EvaluationFunction<KRKP> EvaluateKRKP, EvaluateKPKR; // KR vs KP
-extern EvaluationFunction<KRKB> EvaluateKRKB, EvaluateKBKR; // KR vs KB
-extern EvaluationFunction<KRKN> EvaluateKRKN, EvaluateKNKR; // KR vs KN
-extern EvaluationFunction<KQKR> EvaluateKQKR, EvaluateKRKQ; // KQ vs KR
-extern EvaluationFunction<KBBKN> EvaluateKBBKN, EvaluateKNKBB; // KBB vs KN
-extern EvaluationFunction<KmmKm> EvaluateKmmKm; // K and two minors vs K and one or two minors:
-
-// KBP vs K:
-extern KBPKScalingFunction ScaleKBPK, ScaleKKBP;
-
-// KQ vs KRP:
-extern KQKRPScalingFunction ScaleKQKRP, ScaleKRPKQ;
-
-// KRP vs KR:
-extern KRPKRScalingFunction ScaleKRPKR, ScaleKRKRP;
-
-// KRPP vs KRP:
-extern KRPPKRPScalingFunction ScaleKRPPKRP, ScaleKRPKRPP;
+/// The Endgames namespace handles the pointers to endgame evaluation and scaling
+/// base objects in two std::map. We use polymorphism to invoke the actual
+/// endgame function by calling its virtual operator().
-// King and pawns vs king:
-extern KPsKScalingFunction ScaleKPsK, ScaleKKPs;
+namespace Endgames {
-// KBP vs KB:
-extern KBPKBScalingFunction ScaleKBPKB, ScaleKBKBP;
+ template<typename T> using Ptr = std::unique_ptr<EndgameBase<T>>;
+ template<typename T> using Map = std::unordered_map<Key, Ptr<T>>;
-// KBP vs KN:
-extern KBPKNScalingFunction ScaleKBPKN, ScaleKNKBP;
+ extern std::pair<Map<Value>, Map<ScaleFactor>> maps;
-// KNP vs K:
-extern KNPKScalingFunction ScaleKNPK, ScaleKKNP;
+ void init();
-// KP vs KP:
-extern KPKPScalingFunction ScaleKPKPw, ScaleKPKPb;
+ template<typename T>
+ Map<T>& map() {
+ return std::get<std::is_same<T, ScaleFactor>::value>(maps);
+ }
+ template<EndgameCode E, typename T = eg_type<E>>
+ void add(const std::string& code) {
-////
-//// Prototypes
-////
+ StateInfo st;
+ map<T>()[Position().set(code, WHITE, &st).material_key()] = Ptr<T>(new Endgame<E>(WHITE));
+ map<T>()[Position().set(code, BLACK, &st).material_key()] = Ptr<T>(new Endgame<E>(BLACK));
+ }
-extern void init_bitbases();
+ template<typename T>
+ const EndgameBase<T>* probe(Key key) {
+ auto it = map<T>().find(key);
+ return it != map<T>().end() ? it->second.get() : nullptr;
+ }
+}
+} // namespace Stockfish
-#endif // !defined(ENDGAME_H_INCLUDED)
+#endif // #ifndef ENDGAME_H_INCLUDED