arimaa-engine 0.1.0

A bitboard-based Arimaa game engine: move generation, game state, and Zobrist hashing.
Documentation 
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use std::collections::HashMap;
use std::sync::Arc;

use super::zobrist::Zobrist;

#[derive(Clone, Debug)]
pub struct RepetitionCounts {
    counts: Arc<HashMap<Zobrist, u8>>,
}

impl Default for RepetitionCounts {
    fn default() -> Self {
        Self::new()
    }
}

impl RepetitionCounts {
    pub fn new() -> Self {
        Self { counts: Arc::new(HashMap::new()) }
    }

    pub fn append(&self, hash: Zobrist) -> Self {
        let mut counts = (*self.counts).clone();
        *counts.entry(hash).or_insert(0) += 1;

        Self { counts: Arc::new(counts) }
    }

    pub fn num_repetitions(&self, hash: Zobrist) -> u8 {
        self.counts.get(&hash).copied().unwrap_or(0)
    }
}