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Removed the From<Vec<Cell>> trait to allow insertion of the simpler F…
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…rom<BitBoardState> trait necessary for Army. See issue #1
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@fpiantini
fpiantini committed Oct 31, 2021
1 parent c22c915 commit 969efbf
Showing 1 changed file with 54 additions and 53 deletions.
107 changes: 54 additions & 53 deletions abbadingo/src/bitboard.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -31,7 +31,7 @@ use crate::bbdefines::*;
/// | **Rank 2** | A2 = 8 | B2 | C2 | D2 | E2 | F2 | G2 | H2 = 15|
/// | **Rank 1** | A1 = 0 | B1 = 1 | C1 = 2 | D1 = ..| E1 | F1 | G1 | H1 = 7 |
///
#[derive(Default, Debug, PartialEq, Eq)]
#[derive(Default, Debug, Copy, Clone, PartialEq, Eq)]
pub struct BitBoard {
state: BitBoardState,
}
Expand All @@ -41,6 +41,32 @@ impl BitBoard {
BitBoard { state: EMPTY_STATE }
}

/// [BitBoard] constructor starting from an array of cells.
///
/// The cells in the slice, will be set to active state.
///
/// # Arguments
///
/// * `cells` - A [Cell] slice with the cells to be set on the [BitBoard]
///
/// # Example
/// ```
/// # use abbadingo::bitboard::*;
/// # use abbadingo::bbdefines::*;
/// let mut bb = BitBoard::new();
/// bb.set_cell(Cell::A1);
/// bb.set_cell(Cell::A2);
/// bb.set_cell(Cell::H8);
/// assert_eq!(bb, BitBoard::from_cells(&[Cell::A1, Cell::A2, Cell::H8]));
/// ```
pub fn from_cells(cells: &[Cell]) -> BitBoard {
let mut bb = BitBoard::new();
for c in cells {
bb.set_cell(*c);
}
bb
}

/// Returns `true` if the [BitBoard] is empty.
///
/// A [Cell] inside a [BitBoard] can be free (or empty) or busy.
Expand All @@ -66,7 +92,7 @@ impl BitBoard {
/// assert_eq!(BitBoard::new().is_empty(), true);
///
/// // Builds a BitBoard with the E1 cell busy
/// let bb = BitBoard::from([Cell::E1]);
/// let bb = BitBoard::from_cells(&[Cell::E1]);
/// // _________________________
/// // r8| . . . . . . . . |
/// // r7| . . . . . . . . |
Expand Down Expand Up @@ -107,7 +133,7 @@ impl BitBoard {
/// # use abbadingo::bitboard::*;
/// # use abbadingo::bbdefines::*;
///
/// let mut bb = BitBoard::from([Cell::A1, Cell::H8]);
/// let mut bb = BitBoard::from_cells(&[Cell::A1, Cell::H8]);
/// // _________________________
/// // r8| . . . . . . . o |
/// // r7| . . . . . . . . |
Expand Down Expand Up @@ -263,7 +289,7 @@ impl BitBoard {
/// # use abbadingo::bitboard::*;
/// # use abbadingo::bbdefines::*;
///
/// let mut bb = BitBoard::from([Cell::B2, Cell::G7]);
/// let mut bb = BitBoard::from_cells(&[Cell::B2, Cell::G7]);
/// bb.set_file(File::FileD);
/// // _________________________
/// // r8| . . . o . . . . |
Expand Down Expand Up @@ -299,7 +325,7 @@ impl BitBoard {
/// # use abbadingo::bitboard::*;
/// # use abbadingo::bbdefines::*;
///
/// let mut bb = BitBoard::from([Cell::B2, Cell::G7]);
/// let mut bb = BitBoard::from_cells(&[Cell::B2, Cell::G7]);
/// // BitBoard is not empty:
/// assert!(!bb.is_empty());
/// // Clears the BitBoard:
Expand All @@ -315,32 +341,29 @@ impl BitBoard {
// ----------------------------------------------------------------------------
// Traits implementation for BitBoard structure

/// From trait for the BitBoard struct starting from a slice of [Cell]s.
/// From trait for the BitBoard struct starting from a BitBoardState.
///
/// Converts a slice of cells to a [BitBoard] with all the cells of the slice set to busy (1) status.
/// Set the internal state of the BitBoard to the specified u64 value interpretated as a bitmask.
/// Each bit set to 1 in the u64 value is set to active in the bitboard
///
/// # Arguments
///
/// * `cells` - A [Cell] slice with the cells to be set on the [BitBoard]
/// * `mask` - The bitmask to use to set the cells in the [BitBoard].
///
/// # Example
///```
/// ```
/// # use abbadingo::bitboard::*;
/// # use abbadingo::bbdefines::*;
/// let mut bb = BitBoard::new();
/// bb.set_file(File::FileD);
/// assert_eq!(bb, BitBoard::from([Cell::D1, Cell::D2, Cell::D3, Cell::D4,
/// Cell::D5, Cell::D6, Cell::D7, Cell::D8]));
///```
// The following implementation is the only way I found to work with
// arrays, vectors and slices, but onestly I still do not understand
// it. See:
// https://www.reddit.com/r/rust/comments/70xqpw/using_the_from_trait_not_as_easy_as_i_thought/
impl<'a, T: AsRef<[Cell]>> From<T> for BitBoard {
fn from(cells: T) -> Self {
/// let mut bb = BitBoard::from(0xFF_00_00_00_00_00_00_FF);
/// assert_eq!(bb, BitBoard::from_cells(&[Cell::A8, Cell::B8, Cell::C8, Cell::D8,
/// Cell::E8, Cell::F8, Cell::G8, Cell::H8,
/// Cell::A1, Cell::B1, Cell::C1, Cell::D1,
/// Cell::E1, Cell::F1, Cell::G1, Cell::H1]));
/// ```
impl From<BitBoardState> for BitBoard {
fn from(mask: BitBoardState) -> Self {
let mut bb = BitBoard::new();
for c in cells.as_ref().to_vec() {
bb.set_cell(c);
}
bb.state = mask;
bb
}
}
Expand Down Expand Up @@ -374,28 +397,6 @@ impl fmt::Display for BitBoard {
write!(f, "{}", bb_str)
}
}
// ----------------------------------------------------------------------------

// ------------------------------------------------------------
// FIXME --- Seems impossible to add the From trait for a single
// Cell because conflicts with the From trait for Cell slices.
// i.e. adding the following code cause compilation failure:
//
// impl From<Cell> for BitBoard {
// fn from(c: Cell) -> Self {
// let mut bb = BitBoard::new();
// bb.set_cell(c);
// bb
// }
// }
// Because of this, I was not able to add a method to create a
// BitBoard using a single cell. To do this using the From slice
// trait we have to do this (see tests):
// let bb = BitBoard::from([Cell::H8]);
//
// but these does not work:
// let bb = BitBoard::from(Cell::H8);
// let bb = BitBoard::from(&Cell::H8);

// ****************************************************************************
// TESTS
Expand All @@ -413,16 +414,16 @@ mod tests {
assert_eq!(bb.pop_count(), 0);
}
#[test]
fn init_bitboard_using_a_vector_with_a_cell_in_h8() {
let bb = BitBoard::from([Cell::H8]);
fn create_bitboard_using_a_vector_with_a_cell_in_h8() {
let bb = BitBoard::from_cells(&[Cell::H8]);
assert_eq!(bb.is_empty(), false);
assert_eq!(bb.state, 0x80_00_00_00_00_00_00_00);
assert_eq!(bb.pop_count(), 1);
}
#[test]
fn init_bitboard_using_a_cells_vector_with_active_cell_in_diagonal() {
fn create_bitboard_using_a_cells_vector_with_active_cell_in_diagonal() {
const BBS_DIAGONAL: BitBoardState = 0x80_40_20_10_08_04_02_01;
let bb = BitBoard::from([
let bb = BitBoard::from_cells(&[
Cell::A1,
Cell::B2,
Cell::C3,
Expand All @@ -438,9 +439,9 @@ mod tests {
}

#[test]
fn init_bitboard_using_a_cells_vector_with_active_cell_in_antidiagonal() {
fn create_bitboard_using_a_cells_vector_with_active_cell_in_antidiagonal() {
const BBS_ANTIDIAGONAL: BitBoardState = 0x01_02_04_08_10_20_40_80;
let bb = BitBoard::from([
let bb = BitBoard::from_cells(&[
Cell::A8,
Cell::B7,
Cell::C6,
Expand All @@ -456,8 +457,8 @@ mod tests {
}

#[test]
fn init_bitboard_using_a_cells_vector_with_active_cell_in_diagonal_and_reset_e5() {
let mut bb = BitBoard::from([
fn create_bitboard_using_a_cells_vector_with_active_cell_in_diagonal_and_reset_e5() {
let mut bb = BitBoard::from_cells(&[
Cell::A1,
Cell::B2,
Cell::C3,
Expand Down

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