refactor: return generated arrays

1 files changed, 56 insertions, 35 deletions

diff --git a/src/attacks.rs b/src/attacks.rs
index 141ba44..a8daec9 100644
--- a/src/attacks.rs
+++ b/src/attacks.rs
@@ -1,9 +1,10 @@
-use crate::bitboard::{Bitboard, ls1b, pop_count};
+use crate::bitboard::{Bitboard, ls1b};
 
 static NOT_A_FILE: Bitboard = 0xFEFEFEFEFEFEFEFE;
 static NOT_B_FILE: Bitboard = 0xFDFDFDFDFDFDFDFD;
 static NOT_G_FILE: Bitboard = 0xBFBFBFBFBFBFBFBF;
 static NOT_H_FILE: Bitboard = 0x7F7F7F7F7F7F7F7F;
+static B_FILE: Bitboard =     0x0202020202020202;
 
 /// An array where N-th item is an attack bitboard
 /// of a piece on N-th square
@@ -26,20 +27,33 @@ pub struct Attacks {
     pub knight: AttackTable,
     pub king: AttackTable,
     pub first_rank_attacks: FirstRankAttacks,
+
+    // pub nort_ray: AttackTable,
+    // pub noea_ray: AttackTable,
+    // pub east_ray: AttackTable,
+    // pub soea_ray: AttackTable,
+    // pub sout_ray: AttackTable,
+    // pub sowe_ray: AttackTable,
+    // pub west_ray: AttackTable,
+    // pub nowe_ray: AttackTable,
 }
 
+#[allow(unused)]
 impl Attacks {
     pub fn new() -> Self {
-        let mut knight = [0; 64];
-        let mut king = [0; 64];
-        let mut first_rank_attacks = [[0; 8]; 256];
-        Self::precompute_knight_attacks(&mut knight);
-        Self::precompute_king_attacks(&mut king);
-        Self::precompute_first_rank_attacks(&mut first_rank_attacks);
-        Self { knight, king, first_rank_attacks }
+        let knight = Self::precompute_knight_attacks();
+        let king = Self::precompute_king_attacks();
+        let first_rank_attacks = Self::precompute_first_rank_attacks();
+
+        Self {
+            knight,
+            king,
+            first_rank_attacks,
+        }
     }
 
-    fn precompute_knight_attacks(attacks: &mut AttackTable) {
+    fn precompute_knight_attacks() -> AttackTable {
+        let mut attacks = [0; 64];
         for index in 0..64 {
             let position = 1u64 << index;
             attacks[index] =
@@ -52,9 +66,11 @@ impl Attacks {
                 ((position & NOT_H_FILE) >> 15) |
                 ((position & NOT_A_FILE) >> 17);
         }
+        attacks
     }
 
-    fn precompute_king_attacks(attacks: &mut AttackTable) {
+    fn precompute_king_attacks() -> AttackTable {
+        let mut attacks = [0; 64];
         for index in 0..64 {
             let position = 1u64 << index;
             attacks[index] =
@@ -67,9 +83,13 @@ impl Attacks {
                 (position << 8) |
                 (position >> 8);
         }
+        attacks
     }
 
-    fn precompute_first_rank_attacks(attacks: &mut FirstRankAttacks) {
+
+    fn precompute_first_rank_attacks() -> FirstRankAttacks {
+        let mut attacks = [[0; 8]; 256];
+
         /// Really slow implementation of Most Significant One Bit which is fine to use when pre-computing
         fn log_base_2(bb: Bitboard) -> u64 {
             (bb as f64).log2() as u64
@@ -99,6 +119,7 @@ impl Attacks {
                 }
             }
         }
+        attacks
     }
 }
 
@@ -110,8 +131,8 @@ mod tests {
 
     #[test]
     fn test_knight_attacks() {
-        let attacks = Attacks::new();
-        let e4_attacks = attacks.knight[Square::E4 as usize];
+        let attacks = Attacks::precompute_knight_attacks();
+        let e4_attacks = attacks[Square::E4 as usize];
 
         assert_ne!(e4_attacks & 1 << Square::G5 as usize, 0);
         assert_ne!(e4_attacks & 1 << Square::G3 as usize, 0);
@@ -126,37 +147,37 @@ mod tests {
         assert_eq!(e4_attacks & 1 << Square::D4 as usize, 0);
         assert_eq!(e4_attacks & 1 << Square::A1 as usize, 0);
 
-        assert_eq!(pop_count(attacks.knight[Square::G1 as usize]), 3);
-        assert_eq!(pop_count(attacks.knight[Square::H8 as usize]), 2);
+        assert_eq!(pop_count(attacks[Square::G1 as usize]), 3);
+        assert_eq!(pop_count(attacks[Square::H8 as usize]), 2);
     }
 
     #[test]
     fn test_king_attacks() {
-        let attacks = Attacks::new();
-        assert_eq!(pop_count(attacks.king[Square::E4 as usize]), 8);
-
-        assert_eq!(pop_count(attacks.king[Square::A1 as usize]), 3);
-        assert_eq!(pop_count(attacks.king[Square::A8 as usize]), 3);
-        assert_eq!(pop_count(attacks.king[Square::H1 as usize]), 3);
-        assert_eq!(pop_count(attacks.king[Square::H8 as usize]), 3);
-
-        assert_eq!(pop_count(attacks.king[Square::E1 as usize]), 5);
-        assert_eq!(pop_count(attacks.king[Square::E8 as usize]), 5);
-        assert_eq!(pop_count(attacks.king[Square::A4 as usize]), 5);
-        assert_eq!(pop_count(attacks.king[Square::H4 as usize]), 5);
+        let attacks = Attacks::precompute_king_attacks();
+        assert_eq!(pop_count(attacks[Square::E4 as usize]), 8);
+
+        assert_eq!(pop_count(attacks[Square::A1 as usize]), 3);
+        assert_eq!(pop_count(attacks[Square::A8 as usize]), 3);
+        assert_eq!(pop_count(attacks[Square::H1 as usize]), 3);
+        assert_eq!(pop_count(attacks[Square::H8 as usize]), 3);
+
+        assert_eq!(pop_count(attacks[Square::E1 as usize]), 5);
+        assert_eq!(pop_count(attacks[Square::E8 as usize]), 5);
+        assert_eq!(pop_count(attacks[Square::A4 as usize]), 5);
+        assert_eq!(pop_count(attacks[Square::H4 as usize]), 5);
     }
 
     #[test]
     fn test_first_rank_attacks() {
-        let attacks = Attacks::new();
+        let attacks = Attacks::precompute_first_rank_attacks();
         //                                      HGFEDCBA        HGFEDCBA
-        assert_eq!(attacks.first_rank_attacks[0b00010000][4], 0b11101111, "If rook is the only one on the file, it should be able to attack all rank");
-        assert_eq!(attacks.first_rank_attacks[0b00010001][4], 0b11101111, "If only other piece is on A rank, rook should be able to attack all rank");
-        assert_eq!(attacks.first_rank_attacks[0b10010000][4], 0b11101111, "If only other piece is on H rank, rook should be able to attack all rank");
-        assert_eq!(attacks.first_rank_attacks[0b10010001][4], 0b11101111, "If only other pieces are on A and H ranks, rook should be able to attack all rank");
-        assert_eq!(attacks.first_rank_attacks[0b00010100][4], 0b11101100);
-        assert_eq!(attacks.first_rank_attacks[0b01010100][4], 0b01101100);
-        assert_eq!(attacks.first_rank_attacks[0b01010010][4], 0b01101110);
+        assert_eq!(attacks[0b00010000][4], 0b11101111, "If rook is the only one on the file, it should be able to attack all rank");
+        assert_eq!(attacks[0b00010001][4], 0b11101111, "If only other piece is on A rank, rook should be able to attack all rank");
+        assert_eq!(attacks[0b10010000][4], 0b11101111, "If only other piece is on H rank, rook should be able to attack all rank");
+        assert_eq!(attacks[0b10010001][4], 0b11101111, "If only other pieces are on A and H ranks, rook should be able to attack all rank");
+        assert_eq!(attacks[0b00010100][4], 0b11101100);
+        assert_eq!(attacks[0b01010100][4], 0b01101100);
+        assert_eq!(attacks[0b01010010][4], 0b01101110);
 
     }
 }