chessfriend/board/src/piece_sets/mailbox.rs

// Eryn Wells <eryn@erynwells.me>

use chessfriend_core::{Piece, PlacedPiece, Square};
use std::iter::FromIterator;

#[derive(Clone, Debug, Eq, Hash, PartialEq)]
pub(crate) struct Mailbox([Option<Piece>; Square::NUM]);

impl Mailbox {
    pub(crate) fn new() -> Self {
        Self::default()
    }

    pub(crate) fn get(&self, square: Square) -> Option<Piece> {
        self.0[square as usize]
    }

    pub(crate) fn set(&mut self, piece: Piece, square: Square) {
        self.0[square as usize] = Some(piece);
    }

    pub(crate) fn remove(&mut self, square: Square) {
        self.0[square as usize] = None;
    }

    pub(crate) fn iter(&self) -> impl Iterator<Item = PlacedPiece> {
        self.0
            .into_iter()
            .flatten() // Remove the Nones
            .zip(0u8..) // Enumerate with u8 instead of usize
            .map(|(piece, index)| {
                PlacedPiece::new(piece, unsafe { Square::from_index_unchecked(index) })
            })
    }
}

impl Default for Mailbox {
    fn default() -> Self {
        Self([None; Square::NUM])
    }
}

impl From<[Option<Piece>; Square::NUM]> for Mailbox {
    fn from(value: [Option<Piece>; Square::NUM]) -> Self {
        Mailbox(value)
    }
}

impl FromIterator<PlacedPiece> for Mailbox {
    fn from_iter<T: IntoIterator<Item = PlacedPiece>>(iter: T) -> Self {
        let mut mailbox = Self::new();
        for placed_piece in iter {
            mailbox.set(placed_piece.piece(), placed_piece.square());
        }

        mailbox
    }
}

impl FromIterator<(Square, Piece)> for Mailbox {
    fn from_iter<T: IntoIterator<Item = (Square, Piece)>>(iter: T) -> Self {
        let mut mailbox = Self::new();
        for (square, piece) in iter {
            mailbox.set(piece, square);
        }

        mailbox
    }
}