nac3core/src/typecheck/typedef/mod.rs

@@ -156,6 +156,71 @@ impl Unifier {
         self.set_a_to_b(rigid, b);
     }
 
+    pub fn get_instantiations(&mut self, ty: Type) -> Option<Vec<Type>> {
+        match &*self.get_ty(ty) {
+            TypeEnum::TVar { range, .. } => {
+                let range = range.borrow();
+                if range.is_empty() {
+                    None
+                } else {
+                    Some(
+                        range
+                            .iter()
+                            .map(|ty| self.get_instantiations(*ty).unwrap_or_else(|| vec![*ty]))
+                            .flatten()
+                            .collect_vec(),
+                    )
+                }
+            }
+            TypeEnum::TList { ty } => self
+                .get_instantiations(*ty)
+                .map(|ty| ty.iter().map(|&ty| self.add_ty(TypeEnum::TList { ty })).collect_vec()),
+            TypeEnum::TVirtual { ty } => self.get_instantiations(*ty).map(|ty| {
+                ty.iter().map(|&ty| self.add_ty(TypeEnum::TVirtual { ty })).collect_vec()
+            }),
+            TypeEnum::TTuple { ty } => {
+                let tuples = ty
+                    .iter()
+                    .map(|ty| self.get_instantiations(*ty).unwrap_or_else(|| vec![*ty]))
+                    .multi_cartesian_product()
+                    .collect_vec();
+                if tuples.len() == 1 {
+                    None
+                } else {
+                    Some(
+                        tuples.into_iter().map(|ty| self.add_ty(TypeEnum::TTuple { ty })).collect(),
+                    )
+                }
+            }
+            TypeEnum::TObj { params, .. } => {
+                let (keys, params): (Vec<&u32>, Vec<&Type>) = params.iter().unzip();
+                let params = params
+                    .into_iter()
+                    .map(|ty| self.get_instantiations(*ty).unwrap_or_else(|| vec![*ty]))
+                    .multi_cartesian_product()
+                    .collect_vec();
+                if params.len() <= 1 {
+                    None
+                } else {
+                    Some(
+                        params
+                            .into_iter()
+                            .map(|params| {
+                                self.subst(
+                                    ty,
+                                    &zip(keys.iter().cloned().cloned(), params.iter().cloned())
+                                        .collect(),
+                                )
+                                .unwrap_or(ty)
+                            })
+                            .collect(),
+                    )
+                }
+            }
+            _ => None,
+        }
+    }
+
     pub fn is_concrete(&mut self, a: Type, allowed_typevars: &[Type]) -> bool {
         use TypeEnum::*;
         match &*self.get_ty(a) {

nac3core/src/typecheck/typedef/test.rs

@@ -2,6 +2,7 @@ use super::*;
 use itertools::Itertools;
 use std::collections::HashMap;
 use test_case::test_case;
+use indoc::indoc;
 
 impl Unifier {
     /// Check whether two types are equal.
@@ -473,3 +474,56 @@ fn test_rigid_var() {
     env.unifier.replace_rigid_var(a, int);
     env.unifier.unify(list_x, list_int).unwrap();
 }
+
+#[test]
+fn test_instantiation() {
+    let mut env = TestEnvironment::new();
+    let int = env.parse("int", &HashMap::new());
+    let boolean = env.parse("bool", &HashMap::new());
+    let float = env.parse("float", &HashMap::new());
+    let list_int = env.parse("List[int]", &HashMap::new());
+
+    let obj_map: HashMap<_, _> =
+        [(0usize, "int"), (1, "float"), (2, "bool")].iter().cloned().collect();
+
+    let v = env.unifier.get_fresh_var_with_range(&[int, boolean]).0;
+    let list_v = env.unifier.add_ty(TypeEnum::TList { ty: v });
+    let v1 = env.unifier.get_fresh_var_with_range(&[list_v, int]).0;
+    let v2 = env.unifier.get_fresh_var_with_range(&[list_int, float]).0;
+    let t = env.unifier.get_fresh_rigid_var().0;
+    let tuple = env.unifier.add_ty(TypeEnum::TTuple { ty: vec![v, v1, v2] });
+    let v3 = env.unifier.get_fresh_var_with_range(&[tuple, t]).0;
+    // t = TypeVar('t')
+    // v = TypeVar('v', int, bool)
+    // v1 = TypeVar('v1', 'list[v]', int)
+    // v2 = TypeVar('v2', 'list[int]', float)
+    // v3 = TypeVar('v3', tuple[v, v1, v2], t)
+    // what values can v3 take?
+
+    let types = env.unifier.get_instantiations(v3).unwrap();
+    let expected_types = indoc! {"
+        tuple[bool, int, float]
+        tuple[bool, int, list[int]]
+        tuple[bool, list[bool], float]
+        tuple[bool, list[bool], list[int]]
+        tuple[bool, list[int], float]
+        tuple[bool, list[int], list[int]]
+        tuple[int, int, float]
+        tuple[int, int, list[int]]
+        tuple[int, list[bool], float]
+        tuple[int, list[bool], list[int]]
+        tuple[int, list[int], float]
+        tuple[int, list[int], list[int]]
+        v5"
+    }.split('\n').collect_vec();
+    let types = types
+        .iter()
+        .map(|ty| {
+            env.unifier.stringify(*ty, &mut |i| obj_map.get(&i).unwrap().to_string(), &mut |i| {
+                format!("v{}", i)
+            })
+        })
+        .sorted()
+        .collect_vec();
+    assert_eq!(expected_types, types);
+}