From 8d0856a58df266dfd8411192574e92c4617b42f2 Mon Sep 17 00:00:00 2001 From: pca006132 Date: Mon, 26 Jul 2021 14:38:18 +0800 Subject: [PATCH] added documentation --- nac3core/src/typecheck/typedef/mod.rs | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/nac3core/src/typecheck/typedef/mod.rs b/nac3core/src/typecheck/typedef/mod.rs index 25a2251ac..54b8aeb2d 100644 --- a/nac3core/src/typecheck/typedef/mod.rs +++ b/nac3core/src/typecheck/typedef/mod.rs @@ -219,6 +219,13 @@ impl Unifier { } (TVar { meta: Generic, id, range, .. }, _) => { self.occur_check(a, b)?; + // We check for the range of the type variable to see if unification is allowed. + // Note that although b may be compatible with a, we may have to constrain type + // variables in b to make sure that instantiations of b would always be compatible + // with a. + // The return value x of check_var_compatibility would be a new type that is + // guaranteed to be compatible with a under all possible instantiations. So we + // unify x with b to recursively apply the constrains, and then set a to x. let x = self.check_var_compatibility(*id, b, &range.borrow())?.unwrap_or(b); self.unify(x, b)?; self.set_a_to_b(a, x); @@ -319,6 +326,8 @@ impl Unifier { self.set_a_to_b(a, b); } (TCall(calls1), TCall(calls2)) => { + // we do not unify individual calls, instead we defer until the unification wtih a + // function definition. calls2.borrow_mut().extend_from_slice(&calls1.borrow()); } (TCall(calls), TFunc(signature)) => { @@ -330,6 +339,7 @@ impl Unifier { .map(|v| v.name.clone()) .rev() .collect(); + // we unify every calls to the function signature. for c in calls.borrow().iter() { let Call { posargs, kwargs, ret, fun } = c.as_ref(); let instantiated = self.instantiate_fun(b, signature); @@ -341,6 +351,8 @@ impl Unifier { } else { unreachable!(); } + // we check to make sure that all required arguments (those without default + // arguments) are provided, and do not provide the same argument twice. let mut required = required.clone(); let mut all_names: Vec<_> = signature.args.iter().map(|v| (v.name.clone(), v.ty)).rev().collect();