From dda0fa1a43e1096415ff8f83dd14e6322f1a8e68 Mon Sep 17 00:00:00 2001
From: Marco Costalba <mcostalba@gmail.com>
Date: Sun, 1 Apr 2012 15:12:39 +0100
Subject: [PATCH] Use polymorphism to resolve map() overloading

The 2 overload functions map() accept a pointer to
EndgameBase<Value> or a pointer to EndgameBase<ScaleFactor>.

Because Endgame<E> is derived from one of them we can
directly use a pointer to this class to resolve the
overload as is needed in Endgames::add().

Also made class Endgames fully parametrized and no more
hardcoded to the types (Value or ScaleFactor) of endgames
stored.

No functional change.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
---
 src/endgame.cpp | 10 ++++------
 src/endgame.h   | 21 +++++++++++----------
 2 files changed, 15 insertions(+), 16 deletions(-)

diff --git a/src/endgame.cpp b/src/endgame.cpp
index ec54d4e6..763a402e 100644
--- a/src/endgame.cpp
+++ b/src/endgame.cpp
@@ -116,10 +116,8 @@ Endgames::~Endgames() {
 template<EndgameType E>
 void Endgames::add(const string& code) {
 
-  typedef typename eg_family<E>::type T;
-
-  map((T*)0)[key(code, WHITE)] = new Endgame<E>(WHITE);
-  map((T*)0)[key(code, BLACK)] = new Endgame<E>(BLACK);
+  map((Endgame<E>*)0)[key(code, WHITE)] = new Endgame<E>(WHITE);
+  map((Endgame<E>*)0)[key(code, BLACK)] = new Endgame<E>(BLACK);
 }
 
 
@@ -133,13 +131,13 @@ Value Endgame<KXK>::operator()(const Position& pos) const {
   assert(pos.non_pawn_material(weakerSide) == VALUE_ZERO);
   assert(pos.piece_count(weakerSide, PAWN) == VALUE_ZERO);
 
-	// Stalemate detection with lone king
+  // Stalemate detection with lone king
   if (    pos.side_to_move() == weakerSide
       && !pos.in_check()
       && !MoveList<MV_LEGAL>(pos).size()) {
     return VALUE_DRAW;
   }
-  
+
   Square winnerKSq = pos.king_square(strongerSide);
   Square loserKSq = pos.king_square(weakerSide);
 
diff --git a/src/endgame.h b/src/endgame.h
index 61b8c096..424a3591 100644
--- a/src/endgame.h
+++ b/src/endgame.h
@@ -61,11 +61,12 @@ enum EndgameType {
 };
 
 
-/// Some magic to detect family type of endgame from its enum value
+/// Endgame functions can be of two types according if return a Value or a
+/// ScaleFactor. Type eg_fun<int>::type equals to either ScaleFactor or Value
+/// depending if the template parameter is 0 or 1.
 
-template<bool> struct bool_to_type { typedef Value type; };
-template<> struct bool_to_type<true> { typedef ScaleFactor type; };
-template<EndgameType E> struct eg_family : public bool_to_type<(E > SCALE_FUNS)> {};
+template<int> struct eg_fun { typedef Value type; };
+template<> struct eg_fun<1> { typedef ScaleFactor type; };
 
 
 /// Base and derived templates for endgame evaluation and scaling functions
@@ -79,7 +80,7 @@ struct EndgameBase {
 };
 
 
-template<EndgameType E, typename T = typename eg_family<E>::type>
+template<EndgameType E, typename T = typename eg_fun<(E > SCALE_FUNS)>::type>
 struct Endgame : public EndgameBase<T> {
 
   explicit Endgame(Color c) : strongerSide(c), weakerSide(~c) {}
@@ -97,14 +98,14 @@ private:
 
 class Endgames {
 
-  typedef std::map<Key, EndgameBase<Value>*> M1;
-  typedef std::map<Key, EndgameBase<ScaleFactor>*> M2;
+  typedef std::map<Key, EndgameBase<eg_fun<0>::type>*> M1;
+  typedef std::map<Key, EndgameBase<eg_fun<1>::type>*> M2;
 
   M1 m1;
   M2 m2;
 
-  M1& map(Value*) { return m1; }
-  M2& map(ScaleFactor*) { return m2; }
+  M1& map(M1::value_type::second_type) { return m1; }
+  M2& map(M2::value_type::second_type) { return m2; }
 
   template<EndgameType E> void add(const std::string& code);
 
@@ -113,7 +114,7 @@ public:
   ~Endgames();
 
   template<typename T> EndgameBase<T>* probe(Key key) {
-    return map((T*)0).count(key) ? map((T*)0)[key] : NULL;
+    return map((EndgameBase<T>*)0).count(key) ? map((EndgameBase<T>*)0)[key] : NULL;
   }
 };
 
-- 
2.39.2