From 542a2b39ed811a3795cdce2416896ffaf2a485cf Mon Sep 17 00:00:00 2001
From: mstembera <MissingEmail@email>
Date: Sun, 14 Oct 2018 12:50:31 -0700
Subject: [PATCH] Small simplification in castling rights

There is no need for a special struct with a static member
to generate castling rights.

No functional change.
---
 src/movegen.cpp | 21 +++++++++++----------
 src/pawns.cpp   |  4 ++--
 src/types.h     |  6 ------
 3 files changed, 13 insertions(+), 18 deletions(-)

diff --git a/src/movegen.cpp b/src/movegen.cpp
index 35ca6e77..4532fba5 100644
--- a/src/movegen.cpp
+++ b/src/movegen.cpp
@@ -25,9 +25,10 @@
 
 namespace {
 
-  template<CastlingRight Cr, bool Checks, bool Chess960>
-  ExtMove* generate_castling(const Position& pos, ExtMove* moveList, Color us) {
+  template<Color Us, CastlingSide Cs, bool Checks, bool Chess960>
+  ExtMove* generate_castling(const Position& pos, ExtMove* moveList) {
 
+    constexpr CastlingRight Cr = Us | Cs;
     constexpr bool KingSide = (Cr == WHITE_OO || Cr == BLACK_OO);
 
     if (pos.castling_impeded(Cr) || !pos.can_castle(Cr))
@@ -35,10 +36,10 @@ namespace {
 
     // After castling, the rook and king final positions are the same in Chess960
     // as they would be in standard chess.
-    Square kfrom = pos.square<KING>(us);
+    Square kfrom = pos.square<KING>(Us);
     Square rfrom = pos.castling_rook_square(Cr);
-    Square kto = relative_square(us, KingSide ? SQ_G1 : SQ_C1);
-    Bitboard enemies = pos.pieces(~us);
+    Square kto = relative_square(Us, KingSide ? SQ_G1 : SQ_C1);
+    Bitboard enemies = pos.pieces(~Us);
 
     assert(!pos.checkers());
 
@@ -52,7 +53,7 @@ namespace {
     // Because we generate only legal castling moves we need to verify that
     // when moving the castling rook we do not discover some hidden checker.
     // For instance an enemy queen in SQ_A1 when castling rook is in SQ_B1.
-    if (Chess960 && (attacks_bb<ROOK>(kto, pos.pieces() ^ rfrom) & pos.pieces(~us, ROOK, QUEEN)))
+    if (Chess960 && (attacks_bb<ROOK>(kto, pos.pieces() ^ rfrom) & pos.pieces(~Us, ROOK, QUEEN)))
         return moveList;
 
     Move m = make<CASTLING>(kfrom, rfrom);
@@ -281,13 +282,13 @@ namespace {
     {
         if (pos.is_chess960())
         {
-            moveList = generate_castling<MakeCastling<Us,  KING_SIDE>::right, Checks, true>(pos, moveList, Us);
-            moveList = generate_castling<MakeCastling<Us, QUEEN_SIDE>::right, Checks, true>(pos, moveList, Us);
+            moveList = generate_castling<Us, KING_SIDE, Checks, true>(pos, moveList);
+            moveList = generate_castling<Us, QUEEN_SIDE, Checks, true>(pos, moveList);
         }
         else
         {
-            moveList = generate_castling<MakeCastling<Us,  KING_SIDE>::right, Checks, false>(pos, moveList, Us);
-            moveList = generate_castling<MakeCastling<Us, QUEEN_SIDE>::right, Checks, false>(pos, moveList, Us);
+            moveList = generate_castling<Us, KING_SIDE, Checks, false>(pos, moveList);
+            moveList = generate_castling<Us, QUEEN_SIDE, Checks, false>(pos, moveList);
         }
     }
 
diff --git a/src/pawns.cpp b/src/pawns.cpp
index 75b94c19..36b10f32 100644
--- a/src/pawns.cpp
+++ b/src/pawns.cpp
@@ -250,10 +250,10 @@ Score Entry::do_king_safety(const Position& pos, Square ksq) {
   Value bonus = evaluate_shelter<Us>(pos, ksq);
 
   // If we can castle use the bonus after the castling if it is bigger
-  if (pos.can_castle(MakeCastling<Us, KING_SIDE>::right))
+  if (pos.can_castle(Us | KING_SIDE))
       bonus = std::max(bonus, evaluate_shelter<Us>(pos, relative_square(Us, SQ_G1)));
 
-  if (pos.can_castle(MakeCastling<Us, QUEEN_SIDE>::right))
+  if (pos.can_castle(Us | QUEEN_SIDE))
       bonus = std::max(bonus, evaluate_shelter<Us>(pos, relative_square(Us, SQ_C1)));
 
   return make_score(bonus, -16 * minKingPawnDistance);
diff --git a/src/types.h b/src/types.h
index c9c988ba..9e0f8c3e 100644
--- a/src/types.h
+++ b/src/types.h
@@ -145,12 +145,6 @@ enum CastlingRight {
   CASTLING_RIGHT_NB = 16
 };
 
-template<Color C, CastlingSide S> struct MakeCastling {
-  static constexpr CastlingRight
-  right = C == WHITE ? S == QUEEN_SIDE ? WHITE_OOO : WHITE_OO
-                     : S == QUEEN_SIDE ? BLACK_OOO : BLACK_OO;
-};
-
 enum Phase {
   PHASE_ENDGAME,
   PHASE_MIDGAME = 128,
-- 
2.39.2