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Avoid future should_update() test for thunks containing WHNFs

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This commit is contained in:
Yann Hamdaoui 2021-01-26 12:32:50 +01:00
parent 7d85ae1913
commit 4bcaf4b7fa
1 changed files with 16 additions and 7 deletions
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23
src/eval.rs
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@ -157,6 +157,11 @@ impl Thunk {
self.data.borrow().state
}
/// Set the state to evaluated.
pub fn set_evaluated(&mut self) {
self.data.borrow_mut().state = ThunkState::Evaluated;
}
/// Generate an update frame from this thunk and set the state to `Blackholed`. Return an
/// error if the thunk was already black-holed.
pub fn to_update_frame(&mut self) -> Result<ThunkUpdateFrame, BlackholedError> {
@ -458,15 +463,19 @@ where
.ok_or(EvalError::UnboundIdentifier(x.clone(), pos.clone()))?;
std::mem::drop(env); // thunk may be a 1RC pointer
if thunk.state() != ThunkState::Evaluated
&& should_update(&thunk.borrow().body.term)
{
match thunk.to_update_frame() {
Ok(thunk_upd) => stack.push_thunk(thunk_upd),
Err(BlackholedError) => {
return Err(EvalError::InfiniteRecursion(call_stack, pos))
if thunk.state() != ThunkState::Evaluated {
if should_update(&thunk.borrow().body.term) {
match thunk.to_update_frame() {
Ok(thunk_upd) => stack.push_thunk(thunk_upd),
Err(BlackholedError) => {
return Err(EvalError::InfiniteRecursion(call_stack, pos))
}
}
}
// If the thunk isn't to be updated, directly set the evaluated flag.
else {
thunk.set_evaluated();
}
}
call_stack.push(StackElem::Var(thunk.ident_kind(), x, pos));