added algebraic support for coordinates

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/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));
+}