fully support FEN strings now

strings

cpp/src/board.cpp

@@ -1,6 +1,7 @@
 #include "board.hpp"
 
 #include "coords.hpp"
+#include "move.hpp"
 #include "pieces/piece.hpp"
 
 #include <algorithm>
@@ -19,6 +20,7 @@ Board Board::setup_fen_position(std::string fen) {
         {'q', Piece::Queen},
     };
 
+    // -- Pieces
     std::string fen_board = fen.substr(0, fen.find(' '));
     int rank = 7, file = 0;
     for (char symbol : fen_board) {
@@ -39,6 +41,57 @@ Board Board::setup_fen_position(std::string fen) {
             file++;
         }
     }
+
+    // -- Active colour
+    int index = fen.find(' ');
+    index++;
+    board.white_to_play = fen[index] == 'w';
+
+    // Castling Rights
+    index += 2;
+    for (char symbol : fen.substr(index, fen.find(' ', index + 1))) {
+        index++;
+        if (symbol == ' ' || symbol == '-') {
+            if (symbol == '-')
+                index++;
+            break;
+        }
+
+        switch (symbol) {
+        case 'K':
+            board.w_castle_rights |= CastleSide::KingSide;
+            break;
+        case 'Q':
+            board.w_castle_rights |= CastleSide::QueenSide;
+            break;
+        case 'k':
+            board.b_castle_rights |= CastleSide::KingSide;
+            break;
+        case 'q':
+            board.b_castle_rights |= CastleSide::QueenSide;
+            break;
+        }
+    }
+
+    // -- En passant target
+    if (fen[index] != '-') {
+        Coords c = Coords::from_algebraic(fen.substr(index, 2));
+        index += 2;
+        board.en_passant_target = c.to_index();
+    } else {
+        index++;
+    }
+
+    // -- Half move clock
+    index = fen.find(' ', index) + 1;
+    board.n_half_moves =
+        std::stoi(fen.substr(index, fen.find(' ', index + 1) - index));
+
+    // -- Full move number
+    index = fen.find(' ', index) + 1;
+    board.n_full_moves = std::stoi(fen.substr(index));
+
+
     return board;
 }
 
@@ -53,15 +106,16 @@ std::string Board::to_fen() const {
     };
 
     std::string ret;
+    // -- Pieces
     for (int rank = 7; rank >= 0; rank--) {
         int empty_cell_counter = 0;
         for (int file = 0; file < 8; file++) {
-            if (this->squares[rank * 8 + file] == Piece::None) {
+            if (squares[rank * 8 + file] == Piece::None) {
                 empty_cell_counter++;
                 continue;
             }
 
-            int full_piece = this->squares[rank * 8 + file];
+            int full_piece = squares[rank * 8 + file];
             char piece = p2c[full_piece & 0b111];
             int8_t colour = colour_at({file, rank});
 
@@ -76,6 +130,41 @@ std::string Board::to_fen() const {
         if (rank > 0)
             ret += "/";
     }
+    ret += " ";
+
+    // -- Active colour
+    ret += white_to_play ? 'w' : 'b';
+    ret += " ";
+
+    // -- Castling Rights
+    if (w_castle_rights == CastleSide::NeitherSide
+        && b_castle_rights == CastleSide::NeitherSide)
+        ret += '-';
+    else {
+        if (w_castle_rights & CastleSide::KingSide)
+            ret += 'K';
+        if (w_castle_rights & CastleSide::QueenSide)
+            ret += 'Q';
+        if (b_castle_rights & CastleSide::KingSide)
+            ret += 'k';
+        if (b_castle_rights & CastleSide::QueenSide)
+            ret += 'q';
+    }
+    ret += ' ';
+
+    // -- En passant target
+    ret += en_passant_target == -1
+             ? "-"
+             : Coords::from_index(en_passant_target).to_algebraic();
+    ret += ' ';
+
+    // -- Half move clock
+    ret += std::to_string(n_half_moves);
+    ret += ' ';
+
+    // -- Full moves number
+    ret += std::to_string(n_full_moves);
+
     return ret;
 }
 

cpp/src/board.hpp

@@ -12,9 +12,12 @@ struct Board {
 
   public:
     int8_t squares[64] = {Piece::None};
-    bool white_to_play;
+    bool white_to_play = true;
-    CastleSide w_castle_rights;
+    int8_t w_castle_rights = CastleSide::NeitherSide;
-    CastleSide b_castle_rights;
+    int8_t b_castle_rights = CastleSide::NeitherSide;
+    int8_t en_passant_target = -1;
+    uint8_t n_half_moves = 0;
+    uint8_t n_full_moves = 0;
 
     static Board setup_fen_position(std::string fen);
 

cpp/src/coords.hpp

@@ -1,10 +1,18 @@
 #pragma once
 
 #include <cstdint>
+#include <iostream>
+#include <stdexcept>
+#include <string>
+
+static std::string _FILES = "abcdefgh";
+static std::string _RANKS = "12345678";
 
 struct Coords {
     int x, y;
 
+    Coords(int x, int y): x(x), y(y) {}
+
     int8_t to_index() const {
         return this->y * 8 + this->x;
     }
@@ -13,7 +21,50 @@ struct Coords {
         return {idx % 8, idx / 8};
     }
 
+    static Coords from_algebraic(std::string pos) {
+        if (pos.size() != 2)
+            throw std::invalid_argument(
+                "An algebraic coordinate should only have two characters"
+            );
+
+        int x = _FILES.find(pos[0]);
+        if (x == std::string::npos)
+            throw std::invalid_argument("The first character of the given "
+                                        "algebraic coordinate is invalid");
+
+        int y = _RANKS.find(pos[1]);
+        if (y == std::string::npos)
+            throw std::invalid_argument("The second character of the given "
+                                        "algebraic coordinate is invalid");
+
+        return Coords{x, y};
+    }
+
+    std::string to_algebraic() const {
+        std::string ret;
+        if (x > 7 || y > 7)
+            throw std::invalid_argument(
+                "Can't give the algebraic vesion of an invalid coord"
+            );
+        ret += _FILES[x];
+        ret += _RANKS[y];
+        return ret;
+    }
+
     bool is_within_bounds() const {
         return this->to_index() < 64;
     }
 };
+
+inline bool operator==(const Coords& a, const Coords& b) {
+    return a.x == b.x && a.y == b.y;
+}
+
+inline bool operator!=(const Coords& a, const Coords& b) {
+    return !(a == b);
+}
+
+inline std::ostream& operator<<(std::ostream& os, const Coords& coords) {
+    os << coords.to_algebraic();
+    return os;
+}

cpp/src/main.cpp

@@ -6,5 +6,6 @@ int main(int argc, char* argv[]) {
     std::string pos =
         "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1";
     Board b = Board::setup_fen_position(pos);
+    sizeof(b);
     return 0;
 }

cpp/src/pieces/king.cpp

@@ -49,9 +49,9 @@ std::vector<Move> king_moves(const Board& b, const Coords xy) {
         return ret;
 
     // -- Castles
-    CastleSide castling_rights = b.colour_at(xy) == Colour::White
+    int8_t castling_rights = b.colour_at(xy) == Colour::White
-                                   ? b.w_castle_rights
+                               ? b.w_castle_rights
-                                   : b.b_castle_rights;
+                               : b.b_castle_rights;
 
     if (castling_rights == CastleSide::NeitherSide)
         return ret;

cpp/src/pieces/queen.cpp

@@ -5,7 +5,7 @@
 
 #include <vector>
 
-std::vector<Move> rook_moves(const Board& b, const Coords xy) {
+std::vector<Move> queen_moves(const Board& b, const Coords xy) {
     std::vector<Move> ret;
     auto e = look_direction(b, xy, 1, 0);
     ret.insert(ret.end(), e.begin(), e.end());

cpp/tests/fen.cpp

@@ -2,21 +2,22 @@
 #include "lib.hpp"
 
 int main() {
-    std::string pos = "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR";
+    std::string pos =
-    ASSERT_EQUALS(pos, Board::setup_fen_position(pos)->to_fen());
+        "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1";
+    ASSERT_EQUALS(pos, Board::setup_fen_position(pos).to_fen());
 
-    pos = "r1bk3r/p2pBpNp/n4n2/1p1NP2P/6P1/3P4/P1P1K3/q5b1";
+    pos = "r1bk3r/p2pBpNp/n4n2/1p1NP2P/6P1/3P4/P1P1K3/q5b1 b Qk - 0 1";
-    ASSERT_EQUALS(pos, Board::setup_fen_position(pos)->to_fen());
+    ASSERT_EQUALS(pos, Board::setup_fen_position(pos).to_fen());
 
-    pos = "rnbqkbnr/pppppppp/8/8/4P3/8/PPPP1PPP/RNBQKBNR";
+    pos = "rnbqkbnr/pppppppp/8/8/4P3/8/PPPP1PPP/RNBQKBNR b KQkq e3 0 1";
-    ASSERT_EQUALS(pos, Board::setup_fen_position(pos)->to_fen());
+    ASSERT_EQUALS(pos, Board::setup_fen_position(pos).to_fen());
 
-    pos = "4k2r/6r1/8/8/8/8/3R4/R3K3";
+    pos = "4k2r/6r1/8/8/8/8/3R4/R3K3 w Qk - 0 1";
-    ASSERT_EQUALS(pos, Board::setup_fen_position(pos)->to_fen());
+    ASSERT_EQUALS(pos, Board::setup_fen_position(pos).to_fen());
 
-    pos = "8/8/8/4p1K1/2k1P3/8/8/8";
+    pos = "8/8/8/4p1K1/2k1P3/8/8/8 b - - 0 1";
-    ASSERT_EQUALS(pos, Board::setup_fen_position(pos)->to_fen());
+    ASSERT_EQUALS(pos, Board::setup_fen_position(pos).to_fen());
 
-    pos = "8/5k2/3p4/1p1Pp2p/pP2Pp1P/P4P1K/8/8";
+    pos = "8/5k2/3p4/1p1Pp2p/pP2Pp1P/P4P1K/8/8 b - - 99 50";
-    ASSERT_EQUALS(pos, Board::setup_fen_position(pos)->to_fen());
+    ASSERT_EQUALS(pos, Board::setup_fen_position(pos).to_fen());
 }

cpp/tests/lib.hpp

@@ -2,11 +2,15 @@
 
 #include <iostream>
 
-#define ASSERT_EQUALS(expected, actual)                                        \
+#define ASSERT_EQUALS(x, y)                                                    \
     {                                                                          \
-        if (expected != actual)                                                \
+        auto expected = x;                                                     \
-            std::cout << "Expected: " << std::endl                             \
+        auto actual = y;                                                       \
+        if (expected != actual) {                                              \
+            std::cerr << "Expected: " << std::endl                             \
                       << '\t' << expected << std::endl                         \
                       << "Got: " << std::endl                                  \
                       << '\t' << actual << std::endl;                          \
+            exit(1);                                                           \
+        }                                                                      \
     }

cpp/tests/positions.cpp

@@ -0,0 +1,20 @@
+#include "../src/coords.hpp"
+#include "lib.hpp"
+
+int main() {
+    ASSERT_EQUALS(Coords(0, 0).to_algebraic(), "a1");
+    ASSERT_EQUALS(Coords(1, 0).to_algebraic(), "b1");
+
+    ASSERT_EQUALS(Coords(2, 1).to_algebraic(), "c2");
+    ASSERT_EQUALS(Coords(4, 2).to_algebraic(), "e3");
+
+    ASSERT_EQUALS(Coords(7, 7).to_algebraic(), "h8");
+
+    ASSERT_EQUALS(Coords::from_algebraic("a1"), Coords(0, 0));
+    ASSERT_EQUALS(Coords::from_algebraic("b1"), Coords(1, 0));
+
+    ASSERT_EQUALS(Coords::from_algebraic("c2"), Coords(2, 1));
+    ASSERT_EQUALS(Coords::from_algebraic("e3"), Coords(4, 2));
+
+    ASSERT_EQUALS(Coords::from_algebraic("h8"), Coords(7, 7));
+}