othello/src/logic/move.rs
2025-03-20 01:15:08 -04:00

86 lines
2.9 KiB
Rust

use super::board_value::BoardValueMap;
use crate::repr::{Board, CoordPair, Piece, Winner};
use allocative::Allocative;
use std::sync::LazyLock;
#[derive(Clone, Debug, Allocative)]
pub struct Move {
/// Coordinates (i, j) of the move (if it exists)
pub coord: Option<CoordPair>,
/// Current winner of the match
pub winner: Winner,
/// Index of this move's parent
pub parent: Option<usize>,
/// Indices of this Move's Children
// PERF! this accounts for ~40% of memory usage
// I'm thinking maybe switching to this actually being `Vec<Box<Move>>`
// and ditching the entire `Arena` idea, that would have
// cascading effects though, something to think about
pub children: Vec<usize>,
/// Has this [`Move`] already attempted to create children?
pub tried_children: bool,
/// Value of this move (including children)
pub value: Option<i32>,
/// What is the inherit value of this move (not including children)
pub self_value: i16,
/// Which color made a move on this move?
pub color: Piece,
/// Was this move's children previously trimmed?
pub is_trimmed: bool,
}
const BVM: BoardValueMap = BoardValueMap::weighted();
impl Move {
pub fn new(coord: Option<CoordPair>, board: Board, color: Piece, agent_color: Piece) -> Self {
let mut m = Move {
coord,
winner: board.game_winner(),
parent: None,
children: Vec::new(),
value: None,
color,
is_trimmed: false,
self_value: 0,
tried_children: false,
};
m.self_value = m.compute_self_value(agent_color, &board);
m
}
fn compute_self_value(&self, agent_color: Piece, board: &Board) -> i16 {
if self.winner == Winner::Player(!agent_color) {
// if this board results in the opponent winning, MAJORLY negatively weigh this move
// NOTE! this branch isn't completely deleted because if so, the bot wouldn't make a move.
// We shouldn't prune branches because we still need to always react to the opponent's moves
return i16::MIN + 1;
} else if self.winner == Winner::Player(agent_color) {
// results in a win for the agent
return i16::MAX - 1;
}
// else if self.winner == Winner::Tie {
// // idk what a Tie should be valued?
// return 0;
// }
// I guess ignore Ties here, don't give them an explicit value,
// because even in the case of ties, we want to have a higher score
BVM.board_value(board, agent_color)
}
/// Sort children of the [`Move`] by their self_value in `arena`
pub fn sort_children(&mut self, arena: &[Move]) {
self.children.sort_by(|&a, &b| {
arena[b].value.cmp(&arena[a].value) // Descending order for agent's max nodes
});
}
}