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use std::fmt::Debug;
use std::fmt::Error;
use std::fmt::Formatter;
use myopic_core::*;
use crate::ChessBoard;
use crate::imp::Board;
use crate::imp::cache::rays::RaySet;
use crate::MoveComputeType;
#[derive(Clone)]
pub struct MoveConstraints {
data: [BitBoard; 64],
}
impl PartialEq<MoveConstraints> for MoveConstraints {
fn eq(&self, other: &MoveConstraints) -> bool {
self.data
.iter()
.zip(other.data.iter())
.all(|(l, r)| *l == *r)
}
}
impl Debug for MoveConstraints {
fn fmt(&self, f: &mut Formatter) -> Result<(), Error> {
self.data.to_vec().fmt(f)
}
}
impl MoveConstraints {
pub fn get(&self, location: Square) -> BitBoard {
self.data[location as usize]
}
pub fn all_universal() -> MoveConstraints {
MoveConstraints {
data: [BitBoard::ALL; 64],
}
}
pub fn all_empty() -> MoveConstraints {
MoveConstraints {
data: [BitBoard::EMPTY; 64],
}
}
pub fn all(bitboard: BitBoard) -> MoveConstraints {
MoveConstraints {
data: [bitboard; 64],
}
}
fn intersect(&mut self, location: Square, constraint: BitBoard) {
let curr = self.data[location as usize];
self.data[location as usize] = curr & constraint;
}
fn intersect_pins(&mut self, pinned: &RaySet) {
for loc in pinned.ray_points {
self.intersect(loc, pinned.ray(loc).unwrap_or(BitBoard::ALL))
}
}
fn set(&mut self, location: Square, constraint: BitBoard) {
self.data[location as usize] = constraint;
}
}
impl Board {
pub fn constraints_impl(&mut self, computation_type: MoveComputeType) -> MoveConstraints {
match computation_type {
MoveComputeType::Attacks => self.compute_constraints(computation_type),
MoveComputeType::AttacksChecks => self.compute_constraints(computation_type),
_ => match &self.cache.move_constraints {
Some(x) => x.clone(),
None => {
let result = self.compute_constraints(computation_type);
self.cache.move_constraints = Some(result.clone());
result
}
},
}
}
fn compute_constraints(&mut self, computation_type: MoveComputeType) -> MoveConstraints {
let passive_control = self.passive_control_impl();
let pinned = self.pinned_set_impl();
if passive_control.contains(self.king(self.active)) {
self.check(passive_control, &pinned)
} else {
match computation_type {
MoveComputeType::All => self.any(passive_control, &pinned),
MoveComputeType::Attacks => self.attacks(passive_control, &pinned, false),
MoveComputeType::AttacksChecks => self.attacks(passive_control, &pinned, true),
}
}
}
fn any(&self, passive_control: BitBoard, pinned: &RaySet) -> MoveConstraints {
let mut constraints = MoveConstraints::all_universal();
constraints.set(self.king(self.active), !passive_control);
constraints.intersect_pins(pinned);
constraints
}
fn attacks(&self, passive_control: BitBoard, pinned: &RaySet, checks: bool) -> MoveConstraints {
let (whites, blacks) = self.sides();
let (active, passive) = (self.active, self.active.reflect());
let mut constraints = MoveConstraints::all_universal();
constraints.intersect_pins(pinned);
let enpassant_set = self.enpassant.map_or(BitBoard::EMPTY, |sq| sq.lift());
let passive_locs = self.side(passive);
if !checks {
for piece in Piece::of(active) {
let enpassant = if piece.is_pawn() {
enpassant_set
} else {
BitBoard::EMPTY
};
for loc in self.locs(&[piece]) {
constraints.intersect(loc, passive_locs | enpassant);
}
}
} else {
let discoveries = self.compute_discoveries();
let passive_king = self.king(passive);
let promotion_rays = Piece::WQ.control(passive_king, whites, blacks);
let promotion_jumps = Piece::WN.empty_control(passive_king);
let promotion_checks =
(promotion_rays | promotion_jumps) & active.pawn_promoting_dest_rank();
for piece in Piece::of(active) {
let is_pawn = piece.is_pawn();
let enpassant = if is_pawn {
enpassant_set
} else {
BitBoard::EMPTY
};
let check_squares = piece.reflect().control(passive_king, whites, blacks);
let promotion = if is_pawn {
promotion_checks
} else {
BitBoard::EMPTY
};
for loc in self.locs(&[piece]) {
let discov = discoveries.ray(loc).map(|r| !r).unwrap_or(BitBoard::EMPTY);
constraints.intersect(
loc,
passive_locs | check_squares | enpassant | discov | promotion,
);
}
}
}
constraints.intersect(self.king(active), !passive_control);
constraints
}
fn check(&self, passive_control: BitBoard, pinned: &RaySet) -> MoveConstraints {
let active_king_loc = self.king(self.active);
let attackers = self.compute_king_attackers();
if attackers.len() == 1 {
let (piece, attack_location) = attackers[0];
let blocking_squares = if piece.is_knight() {
attack_location.lift()
} else {
BitBoard::cord(attack_location, active_king_loc)
};
let mut constraint = MoveConstraints::all(blocking_squares);
constraint.intersect_pins(pinned);
constraint.set(active_king_loc, !passive_control);
constraint
} else {
let mut constraint = MoveConstraints::all_empty();
constraint.set(active_king_loc, !passive_control);
constraint
}
}
fn compute_king_attackers(&self) -> Vec<(Piece, Square)> {
let (whites, blacks) = self.sides();
let king_loc = self.king(self.active);
pnbrq(self.active.reflect())
.iter()
.flat_map(|&p| self.pieces.locs(p).into_iter().map(move |s| (p, s)))
.filter(|(p, s)| p.control(*s, whites, blacks).contains(king_loc))
.collect()
}
}
fn pnbrq<'a>(side: Side) -> &'a [Piece; 5] {
match side {
Side::White => &[Piece::WP, Piece::WN, Piece::WB, Piece::WR, Piece::WQ],
Side::Black => &[Piece::BP, Piece::BN, Piece::BB, Piece::BR, Piece::BQ],
}
}