scopegraphs 0.3.3

A well-documented port of scopegraphs to Rust
Documentation 
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use crate::completeness::private::Sealed;
use crate::completeness::{
    Completeness, CriticalEdgeBasedCompleteness, CriticalEdgeSet, Delay, EdgeClosedError,
    EdgesOrDelay,
};
use crate::scopegraph::{InnerScopeGraph, Scope};
use crate::Label;
use std::{collections::HashSet, hash::Hash};

use super::{UserClosed, Witness};

/// Critical-edge based [`Completeness`] implementation.
///
/// Unlike [`ImplicitClose`](super::ImplicitClose), this implementation shifts responsibility of closing edges to the
/// _type checker writer_. I.e., they have to insert `sg.close(scope, label)` statements at the
/// appropriate positions in the code.
///
/// Returns [`EdgeClosedError`] when an edge is added to a scope in which the label is already
/// closed (by an explicit close of the type checker writer).
///
/// Returns [`Delay`] when edges are retrieved (e.g. during query resolution) for an edge that is
/// not yet closed.
#[derive(Debug)]
pub struct ExplicitClose<LABEL: Label> {
    critical_edges: CriticalEdgeSet<LABEL>,
}

impl<LABEL: Label> Default for ExplicitClose<LABEL> {
    fn default() -> Self {
        ExplicitClose {
            critical_edges: CriticalEdgeSet::default(),
        }
    }
}

impl<LABEL: Label> Sealed for ExplicitClose<LABEL> {}

impl<LABEL: Hash + Label, DATA> Completeness<LABEL, DATA> for ExplicitClose<LABEL> {
    fn cmpl_new_scope(&self, _: &InnerScopeGraph<LABEL, DATA>, _: Scope) {
        <ExplicitClose<LABEL> as CriticalEdgeBasedCompleteness<LABEL, DATA>>::init_scope_with(
            self,
            LABEL::iter().collect(), // init with all labels: programmer is responsible for closing edges
        )
    }

    fn cmpl_new_complete_scope(&self, _: &InnerScopeGraph<LABEL, DATA>, _: Scope) {
        <ExplicitClose<LABEL> as CriticalEdgeBasedCompleteness<LABEL, DATA>>::init_scope_with(
            self,
            HashSet::new(), // init with empty label set to prevent extension
        )
    }

    type NewEdgeResult = Result<(), EdgeClosedError<LABEL>>;

    fn cmpl_new_edge(
        &self,
        inner_scope_graph: &InnerScopeGraph<LABEL, DATA>,
        src: Scope,
        lbl: LABEL,
        dst: Scope,
    ) -> Self::NewEdgeResult {
        if self.critical_edges.is_open(src, &lbl) {
            inner_scope_graph.add_edge(src, lbl, dst);
            Ok(())
        } else {
            Err(EdgeClosedError {
                scope: src,
                label: lbl,
            })
        }
    }

    type GetEdgesResult<'rslv>
        = EdgesOrDelay<Vec<Scope>, LABEL>
    where
        Self: 'rslv,
        LABEL: 'rslv,
        DATA: 'rslv;

    fn cmpl_get_edges<'rslv>(
        &self,
        inner_scope_graph: &InnerScopeGraph<LABEL, DATA>,
        src: Scope,
        lbl: LABEL,
    ) -> Self::GetEdgesResult<'rslv>
    where
        LABEL: 'rslv,
        DATA: 'rslv,
    {
        if self.critical_edges.is_open(src, &lbl) {
            Err(Delay {
                scope: src,
                label: lbl,
            })
        } else {
            Ok(inner_scope_graph.get_edges(src, lbl))
        }
    }
}

impl<LABEL: Hash + Label, DATA> CriticalEdgeBasedCompleteness<LABEL, DATA>
    for ExplicitClose<LABEL>
{
    fn init_scope_with(&self, open_labels: HashSet<LABEL>) {
        self.critical_edges.init_scope(open_labels)
    }
}

impl<LABEL: Hash + Label, DATA> UserClosed<LABEL, DATA> for ExplicitClose<LABEL> {
    /// Close a scope for a certain label
    /// // TODO: link to "closing" in concepts
    fn close(&self, scope: Scope, label: &LABEL, _witness: Witness) {
        self.critical_edges.close(scope, label);
    }
}