Use single-element tuples in facts

...instead of bare indexes. This makes some macros easier to write.

Author: ecstatic-morse

polonius-engine/src/facts.rs

@@ -11,7 +11,7 @@ pub struct AllFacts<T: FactTypes> {
     pub loan_issued_at: Vec<(T::Origin, T::Loan, T::Point)>,
 
     /// `universal_region(origin)` -- this is a "free region" within fn body
-    pub universal_region: Vec<T::Origin>,
+    pub universal_region: Vec<(T::Origin,)>,
 
     /// `cfg_edge(point1, point2)` for each edge `point1 -> point2` in the control flow
     pub cfg_edge: Vec<(T::Point, T::Point)>,

polonius-engine/src/output/liveness.rs

@@ -157,12 +157,12 @@ pub(super) fn compute_live_origins<T: FactTypes>(
 pub(super) fn make_universal_regions_live<T: FactTypes>(
     origin_live_on_entry: &mut Vec<(T::Origin, T::Point)>,
     cfg_node: &BTreeSet<T::Point>,
-    universal_regions: &[T::Origin],
+    universal_regions: &[(T::Origin,)],
 ) {
     debug!("make_universal_regions_live()");
 
     origin_live_on_entry.reserve(universal_regions.len() * cfg_node.len());
-    for &origin in universal_regions.iter() {
+    for &(origin,) in universal_regions.iter() {
         for &point in cfg_node.iter() {
             origin_live_on_entry.push((origin, point));
         }

polonius-engine/src/output/mod.rs

@@ -255,7 +255,7 @@ impl<T: FactTypes> Output<T> {
             all_facts
                 .universal_region
                 .iter()
-                .map(|&origin| (origin, ())),
+                .map(|&origin| (origin.0, ())),
         );
 
         let placeholder_loan = Relation::from_iter(

src/program.rs

@@ -14,7 +14,7 @@ use crate::intern::InternerTables;
 #[derive(Default)]
 struct Facts {
     loan_issued_at: BTreeSet<(Origin, Loan, Point)>,
-    universal_region: BTreeSet<Origin>,
+    universal_region: BTreeSet<(Origin,)>,
     cfg_edge: BTreeSet<(Point, Point)>,
     loan_killed_at: BTreeSet<(Loan, Point)>,
     subset_base: BTreeSet<(Origin, Origin, Point)>,
@@ -72,7 +72,7 @@ pub(crate) fn parse_from_program(
         input
             .placeholders
             .iter()
-            .map(|placeholder| tables.origins.intern(&placeholder.origin)),
+            .map(|placeholder| (tables.origins.intern(&placeholder.origin),)),
     );
 
     // facts: placeholder(Origin, Loan)
@@ -296,7 +296,7 @@ mod tests {
         let universal_regions: Vec<_> = facts
             .universal_region
             .iter()
-            .map(|origin| tables.origins.untern(*origin))
+            .map(|origin| tables.origins.untern(origin.0))
             .collect();
         assert_eq!(universal_regions, ["'a", "'b", "'c"]);
 

src/tab_delim.rs

@@ -90,6 +90,19 @@ where
     }
 }
 
+impl<'input, T> FromTabDelimited<'input> for (T,)
+where
+    &'input str: InternTo<T>,
+{
+    fn parse(
+        tables: &mut InternerTables,
+        inputs: &mut dyn Iterator<Item = &'input str>,
+    ) -> Option<Self> {
+        let input = inputs.next()?;
+        Some((InternTo::intern(tables, input),))
+    }
+}
+
 impl<'input, T> FromTabDelimited<'input> for T
 where
     &'input str: InternTo<T>,