mod fold;
mod fold_from;
mod multiset;
mod reduce;
mod set;

pub use fold::HalfJoinStateFold;
pub use fold_from::HalfJoinStateFoldFrom;
pub use multiset::HalfMultisetJoinState;
pub use reduce::HalfJoinStateReduce;
pub use set::HalfSetJoinState;
use smallvec::SmallVec;

pub trait HalfJoinState<Key, ValBuild, ValProbe> {
    /// Insert a key value pair into the join state, currently this is always inserting into a hash table
    /// If the key-value pair exists then it is implementation defined what happens, usually either two copies are stored or only one copy is stored.
    fn build(&mut self, k: Key, v: &ValBuild) -> bool;

    /// This function does the actual joining part of the join. It looks up a key in the local join state and creates matches
    /// The first match is return directly to the caller, and any additional matches are stored internally to be retrieved later with `pop_match`
    fn probe(&mut self, k: &Key, v: &ValProbe) -> Option<(Key, ValProbe, ValBuild)>;

    /// If there are any stored matches from previous calls to probe then this function will remove them one at a time and return it.
    fn pop_match(&mut self) -> Option<(Key, ValProbe, ValBuild)>;
    fn len(&self) -> usize;
    fn is_empty(&self) -> bool {
        self.len() == 0
    }
    fn iter(&self) -> std::collections::hash_map::Iter<'_, Key, SmallVec<[ValBuild; 1]>>;
    fn full_probe(&self, k: &Key) -> std::slice::Iter<'_, ValBuild>;
}