[board] Move bitboard lib to "board"

board/src/square.rs

@@ -0,0 +1,103 @@
+// Eryn Wells <eryn@erynwells.me>
+
+use std::str::FromStr;
+
+#[derive(Debug)]
+struct ParseSquareError;
+
+#[derive(Debug)]
+struct SquareIndexOutOfBoundsError;
+
+#[derive(Debug, Eq, PartialEq)]
+struct Square {
+    rank: u8,
+    file: u8,
+}
+
+impl Square {
+    fn from_index(index: u8) -> Result<Square, SquareIndexOutOfBoundsError> {
+        if index >= 64 {
+            return Err(SquareIndexOutOfBoundsError);
+        }
+
+        Ok(Square {
+            rank: index / 8,
+            file: index % 8,
+        })
+    }
+
+    fn from_algebraic_string(s: &str) -> Result<Square, ParseSquareError> {
+        s.parse()
+    }
+
+    fn rank_index(&self) -> usize {
+        self.rank.into()
+    }
+
+    fn file_index(&self) -> usize {
+        self.file.into()
+    }
+}
+
+impl FromStr for Square {
+    type Err = ParseSquareError;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        if !s.is_ascii() || s.len() != 2 {
+            return Err(ParseSquareError);
+        }
+
+        let chars: Vec<char> = s.chars().collect();
+        let rank_char = chars[0].to_ascii_lowercase();
+        if !rank_char.is_ascii_lowercase() {
+            return Err(ParseSquareError);
+        }
+
+        let rank = (rank_char as u8) - ('a' as u8) + 1;
+        if rank < 1 || rank > 8 {
+            return Err(ParseSquareError);
+        }
+
+        let file = u8::try_from(chars[1].to_digit(10).ok_or(ParseSquareError)?)
+            .map_err(|_| ParseSquareError)?;
+
+        Ok(Square {
+            rank: rank - 1,
+            file: file - 1,
+        })
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn indexes() {
+        let sq1 = Square::from_algebraic_string("c5").expect("Failed to parse 'c5' square");
+        assert_eq!(sq1.rank_index(), 2, "Rank doesn't match");
+        assert_eq!(sq1.file_index(), 4, "File doesn't match");
+
+        let sq2 = Square::from_algebraic_string("b2").expect("Failed to parse 'b2' square");
+        assert_eq!(sq2.rank_index(), 1, "Rank doesn't match");
+        assert_eq!(sq2.file_index(), 1, "File doesn't match");
+    }
+
+    #[test]
+    fn parse_good_input() {
+        let sq1 = Square::from_algebraic_string("a4").expect("Failed to parse 'a4' square");
+        assert_eq!(sq1.rank, 0);
+        assert_eq!(sq1.file, 3);
+
+        let sq2 = Square::from_algebraic_string("B8").expect("Failed to parse 'B8' square");
+        assert_eq!(sq2.rank, 1);
+        assert_eq!(sq2.file, 7);
+    }
+
+    #[test]
+    fn from_index() {
+        let sq1 = Square::from_index(4).expect("Unable to get Square from index");
+        assert_eq!(sq1.rank, 0);
+        assert_eq!(sq1.file, 4);
+    }
+}