1/*
2 Stockfish, a UCI chess playing engine derived from Glaurung 2.1
3 Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
4 Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
5 Copyright (C) 2015-2019 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
6
7 Stockfish is free software: you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation, either version 3 of the License, or
10 (at your option) any later version.
11
12 Stockfish is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
16
17 You should have received a copy of the GNU General Public License
18 along with this program. If not, see <http://www.gnu.org/licenses/>.
19*/
20
21#ifndef ENDGAME_H_INCLUDED
22#define ENDGAME_H_INCLUDED
23
24#include <map>
25#include <memory>
26#include <string>
27#include <type_traits>
28#include <utility>
29
30#include "position.h"
31#include "types.h"
32
33
34/// EndgameCode lists all supported endgame functions by corresponding codes
35
36enum EndgameCode {
37
38 EVALUATION_FUNCTIONS,
39 KNNK, // KNN vs K
40 KNNKP, // KNN vs KP
41 KXK, // Generic "mate lone king" eval
42 KBNK, // KBN vs K
43 KPK, // KP vs K
44 KRKP, // KR vs KP
45 KRKB, // KR vs KB
46 KRKN, // KR vs KN
47 KQKP, // KQ vs KP
48 KQKR, // KQ vs KR
49
50 SCALING_FUNCTIONS,
51 KBPsK, // KB and pawns vs K
52 KQKRPs, // KQ vs KR and pawns
53 KRPKR, // KRP vs KR
54 KRPKB, // KRP vs KB
55 KRPPKRP, // KRPP vs KRP
56 KPsK, // K and pawns vs K
57 KBPKB, // KBP vs KB
58 KBPPKB, // KBPP vs KB
59 KBPKN, // KBP vs KN
60 KNPK, // KNP vs K
61 KNPKB, // KNP vs KB
62 KPKP // KP vs KP
63};
64
65
66/// Endgame functions can be of two types depending on whether they return a
67/// Value or a ScaleFactor.
68
69template<EndgameCode E> using
70eg_type = typename std::conditional<(E < SCALING_FUNCTIONS), Value, ScaleFactor>::type;
71
72
73/// Base and derived functors for endgame evaluation and scaling functions
74
75template<typename T>
76struct EndgameBase {
77
78 explicit EndgameBase(Color c) : strongSide(c), weakSide(~c) {}
79 virtual ~EndgameBase() = default;
80 virtual T operator()(const Position&) const = 0;
81
82 const Color strongSide, weakSide;
83};
84
85
86template<EndgameCode E, typename T = eg_type<E>>
87struct Endgame : public EndgameBase<T> {
88
89 explicit Endgame(Color c) : EndgameBase<T>(c) {}
90 T operator()(const Position&) const override;
91};
92
93
94/// The Endgames namespace handles the pointers to endgame evaluation and scaling
95/// base objects in two std::map. We use polymorphism to invoke the actual
96/// endgame function by calling its virtual operator().
97
98namespace Endgames {
99
100 template<typename T> using Ptr = std::unique_ptr<EndgameBase<T>>;
101 template<typename T> using Map = std::map<Key, Ptr<T>>;
102
103 extern std::pair<Map<Value>, Map<ScaleFactor>> maps;
104
105 void init();
106
107 template<typename T>
108 Map<T>& map() {
109 return std::get<std::is_same<T, ScaleFactor>::value>(maps);
110 }
111
112 template<EndgameCode E, typename T = eg_type<E>>
113 void add(const std::string& code) {
114
115 StateInfo st;
116 map<T>()[Position().set(code, WHITE, &st).material_key()] = Ptr<T>(new Endgame<E>(WHITE));
117 map<T>()[Position().set(code, BLACK, &st).material_key()] = Ptr<T>(new Endgame<E>(BLACK));
118 }
119
120 template<typename T>
121 const EndgameBase<T>* probe(Key key) {
122 return map<T>().count(key) ? map<T>()[key].get() : nullptr;
123 }
124}
125
126#endif // #ifndef ENDGAME_H_INCLUDED
127