egglog 2.0.0

egglog is a language that combines the benefits of equality saturation and datalog. It can be used for analysis, optimization, and synthesis of programs. It is the successor to the popular rust library egg.
Documentation 
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use super::*;
use std::collections::BTreeSet;

#[derive(Clone, Debug, PartialEq, Eq, Hash)]
pub struct SetContainer {
    pub do_rebuild: bool,
    pub data: BTreeSet<Value>,
}

impl ContainerValue for SetContainer {
    fn rebuild_contents(&mut self, rebuilder: &dyn Rebuilder) -> bool {
        if self.do_rebuild {
            let mut xs: Vec<_> = self.data.iter().copied().collect();
            let changed = rebuilder.rebuild_slice(&mut xs);
            self.data = xs.into_iter().collect();
            changed
        } else {
            false
        }
    }
    fn iter(&self) -> impl Iterator<Item = Value> + '_ {
        self.data.iter().copied()
    }
}

#[derive(Clone, Debug)]
pub struct SetSort {
    name: String,
    element: ArcSort,
}

impl SetSort {
    pub fn element(&self) -> ArcSort {
        self.element.clone()
    }
}

impl Presort for SetSort {
    fn presort_name() -> &'static str {
        "Set"
    }

    fn reserved_primitives() -> Vec<&'static str> {
        vec![
            "set-of",
            "set-empty",
            "set-insert",
            "set-not-contains",
            "set-contains",
            "set-remove",
            "set-union",
            "set-diff",
            "set-intersect",
            "set-get",
            "set-length",
        ]
    }

    fn make_sort(
        typeinfo: &mut TypeInfo,
        name: String,
        args: &[Expr],
    ) -> Result<ArcSort, TypeError> {
        if let [Expr::Var(span, e)] = args {
            let e = typeinfo
                .get_sort_by_name(e)
                .ok_or(TypeError::UndefinedSort(e.clone(), span.clone()))?;

            if e.is_eq_container_sort() {
                return Err(TypeError::DisallowedSort(
                    name,
                    "Sets nested with other EqSort containers are not allowed".into(),
                    span.clone(),
                ));
            }

            let out = Self {
                name,
                element: e.clone(),
            };
            Ok(out.to_arcsort())
        } else {
            panic!()
        }
    }
}

impl ContainerSort for SetSort {
    type Container = SetContainer;

    fn name(&self) -> &str {
        &self.name
    }

    fn inner_sorts(&self) -> Vec<ArcSort> {
        vec![self.element.clone()]
    }

    fn is_eq_container_sort(&self) -> bool {
        self.element.is_eq_sort()
    }

    fn inner_values(
        &self,
        container_values: &ContainerValues,
        value: Value,
    ) -> Vec<(ArcSort, Value)> {
        let val = container_values
            .get_val::<SetContainer>(value)
            .unwrap()
            .clone();
        val.data
            .iter()
            .map(|e| (self.element.clone(), *e))
            .collect()
    }

    fn register_primitives(&self, eg: &mut EGraph) {
        let arc = self.clone().to_arcsort();

        add_primitive!(eg, "set-empty" = {self.clone(): SetSort} |                      | -> @SetContainer (arc) { SetContainer {
            do_rebuild: self.ctx.element.is_eq_sort(),
            data: BTreeSet::new()
        } });
        add_primitive!(eg, "set-of"    = {self.clone(): SetSort} [xs: # (self.element())] -> @SetContainer (arc) { SetContainer {
            do_rebuild: self.ctx.element.is_eq_sort(),
            data: xs.collect()
        } });

        add_primitive!(eg, "set-get" = |xs: @SetContainer (arc), i: i64| -?> # (self.element()) { xs.data.iter().nth(i as usize).copied() });
        add_primitive!(eg, "set-insert" = |mut xs: @SetContainer (arc), x: # (self.element())| -> @SetContainer (arc) {{ xs.data.insert( x); xs }});
        add_primitive!(eg, "set-remove" = |mut xs: @SetContainer (arc), x: # (self.element())| -> @SetContainer (arc) {{ xs.data.remove(&x); xs }});

        add_primitive!(eg, "set-length"       = |xs: @SetContainer (arc)| -> i64 { xs.data.len() as i64 });
        add_primitive!(eg, "set-contains"     = |xs: @SetContainer (arc), x: # (self.element())| -?> () { ( xs.data.contains(&x)).then_some(()) });
        add_primitive!(eg, "set-not-contains" = |xs: @SetContainer (arc), x: # (self.element())| -?> () { (!xs.data.contains(&x)).then_some(()) });

        add_primitive!(eg, "set-union"      = |mut xs: @SetContainer (arc), ys: @SetContainer (arc)| -> @SetContainer (arc) {{ xs.data.extend(ys.data);                  xs }});
        add_primitive!(eg, "set-diff"       = |mut xs: @SetContainer (arc), ys: @SetContainer (arc)| -> @SetContainer (arc) {{ xs.data.retain(|k| !ys.data.contains(k)); xs }});
        add_primitive!(eg, "set-intersect"  = |mut xs: @SetContainer (arc), ys: @SetContainer (arc)| -> @SetContainer (arc) {{ xs.data.retain(|k|  ys.data.contains(k)); xs }});
    }

    fn reconstruct_termdag(
        &self,
        _container_values: &ContainerValues,
        _value: Value,
        termdag: &mut TermDag,
        element_terms: Vec<TermId>,
    ) -> TermId {
        termdag.app("set-of".into(), element_terms)
    }

    fn serialized_name(&self, _container_values: &ContainerValues, _: Value) -> String {
        "set-of".to_owned()
    }
}