txmap 1.1.0

A concurrent transactional hash map for Rust with fine-grained locking, internal mutability and composable transactions
Documentation 
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use crate::{
    indexed_key::IndexedKey, locks::lock_policy::LockPolicy, new_types::BitMask,
    ops::op_trait::OpTrait, shard::Shard, shard_count::ShardCount,
};
use intmap::IntMap;
use std::hash::Hash;

pub(crate) struct SwapValueOp<K>
where
    K: Hash + Eq,
{
    indexed_key_a: IndexedKey<K>,
    indexed_key_b: IndexedKey<K>,
}

impl<K> SwapValueOp<K>
where
    K: Hash + Eq,
{
    pub fn new(shard_count: u8, a: K, b: K) -> Self {
        Self {
            indexed_key_a: ShardCount::indexed_key(shard_count, a),
            indexed_key_b: ShardCount::indexed_key(shard_count, b),
        }
    }
}

impl<L, K, V, P> OpTrait<L, K, V, P> for SwapValueOp<K>
where
    L: LockPolicy,
    K: Clone + Hash + Eq,
{
    fn guards_bitmask(&self) -> BitMask {
        self.indexed_key_a.2 | self.indexed_key_b.2
    }
    fn apply(&self, mutex_guards: &mut IntMap<u8, L::WriteGuard<'_, Shard<K, V>>>, _: &P) {
        let a = self.indexed_key_a.remove_entry::<L, V>(mutex_guards);
        let b = self.indexed_key_b.remove_entry::<L, V>(mutex_guards);
        match a {
            Some((a_key, a_value)) => match b {
                Some((b_key, b_value)) => {
                    self.indexed_key_a.insert_with_duplicate_key::<L, V>(
                        mutex_guards,
                        a_key,
                        b_value,
                    );
                    self.indexed_key_b.insert_with_duplicate_key::<L, V>(
                        mutex_guards,
                        b_key,
                        a_value,
                    );
                }
                None => {
                    self.indexed_key_b.insert::<L, V>(mutex_guards, a_value);
                }
            },
            None => {
                if let Some((_, b_value)) = b {
                    self.indexed_key_a.insert::<L, V>(mutex_guards, b_value);
                }
            }
        }
    }
}