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-rw-r--r--dhall/src/core/thunk.rs138
-rw-r--r--dhall/src/core/var.rs12
2 files changed, 110 insertions, 40 deletions
diff --git a/dhall/src/core/thunk.rs b/dhall/src/core/thunk.rs
index b6358ef..325a410 100644
--- a/dhall/src/core/thunk.rs
+++ b/dhall/src/core/thunk.rs
@@ -1,5 +1,5 @@
use std::borrow::Cow;
-use std::cell::{Ref, RefCell};
+use std::cell::{Ref, RefCell, RefMut};
use std::rc::Rc;
use dhall_syntax::{Const, ExprF};
@@ -21,7 +21,7 @@ enum Marker {
}
use Marker::{NF, WHNF};
-#[derive(Debug)]
+#[derive(Debug, Clone)]
enum ThunkInternal {
/// Partially normalized value whose subexpressions have been thunked (this is returned from
/// typechecking). Note that this is different from `ValueF::PartialExpr` because there is no
@@ -32,19 +32,29 @@ enum ThunkInternal {
ValueF(Marker, ValueF),
}
+#[derive(Debug)]
+struct TypedThunkInternal {
+ internal: ThunkInternal,
+ typ: Option<Type>,
+}
+
/// Stores a possibly unevaluated value. Gets (partially) normalized on-demand,
/// sharing computation automatically. Uses a RefCell to share computation.
/// Can optionally store a Type from the typechecking phase to preserve type information through
/// the normalization phase.
#[derive(Clone)]
-pub struct Thunk(Rc<RefCell<ThunkInternal>>, Option<Box<Type>>);
+pub struct Thunk(Rc<RefCell<TypedThunkInternal>>);
#[derive(Debug, Clone)]
pub struct TypedThunk(Thunk);
impl ThunkInternal {
- fn into_thunk(self, t: Option<Box<Type>>) -> Thunk {
- Thunk(Rc::new(RefCell::new(self)), t)
+ fn into_thunk(self, t: Option<Type>) -> Thunk {
+ TypedThunkInternal {
+ internal: self,
+ typ: t,
+ }
+ .into_thunk()
}
fn normalize_whnf(&mut self) {
@@ -92,37 +102,78 @@ impl ThunkInternal {
}
}
+impl TypedThunkInternal {
+ fn into_thunk(self) -> Thunk {
+ Thunk(Rc::new(RefCell::new(self)))
+ }
+ fn as_internal(&self) -> &ThunkInternal {
+ &self.internal
+ }
+ fn as_internal_mut(&mut self) -> &mut ThunkInternal {
+ &mut self.internal
+ }
+
+ fn get_type(&self) -> Result<Type, TypeError> {
+ match &self.typ {
+ Some(t) => Ok(t.clone()),
+ None => Err(TypeError::new(
+ &TypecheckContext::new(),
+ TypeMessage::Untyped,
+ )),
+ }
+ }
+}
+
impl Thunk {
pub(crate) fn from_valuef(v: ValueF) -> Thunk {
ThunkInternal::ValueF(WHNF, v).into_thunk(None)
}
pub(crate) fn from_valuef_and_type(v: ValueF, t: Type) -> Thunk {
- ThunkInternal::ValueF(WHNF, v).into_thunk(Some(Box::new(t)))
+ ThunkInternal::ValueF(WHNF, v).into_thunk(Some(t))
}
pub(crate) fn from_partial_expr(e: ExprF<Thunk, Normalized>) -> Thunk {
ThunkInternal::PartialExpr(e).into_thunk(None)
}
pub(crate) fn with_type(self, t: Type) -> Thunk {
- Thunk(self.0, Some(Box::new(t)))
+ self.as_internal().clone().into_thunk(Some(t))
}
- // Normalizes contents to normal form; faster than `normalize_nf` if
- // no one else shares this thunk
- pub(crate) fn normalize_mut(&mut self) {
+ /// Mutates the contents. If no one else shares this thunk,
+ /// mutates directly, thus avoiding a RefCell lock.
+ fn mutate_internal(&mut self, f: impl FnOnce(&mut TypedThunkInternal)) {
match Rc::get_mut(&mut self.0) {
// Mutate directly if sole owner
- Some(refcell) => RefCell::get_mut(refcell).normalize_nf(),
+ Some(refcell) => f(RefCell::get_mut(refcell)),
// Otherwise mutate through the refcell
- None => self.0.borrow_mut().normalize_nf(),
+ None => f(&mut self.as_tinternal_mut()),
}
}
+ /// Normalizes contents to normal form; faster than `normalize_nf` if
+ /// no one else shares this thunk
+ pub(crate) fn normalize_mut(&mut self) {
+ self.mutate_internal(|i| i.as_internal_mut().normalize_nf())
+ }
+
+ fn as_tinternal(&self) -> Ref<TypedThunkInternal> {
+ self.0.borrow()
+ }
+ fn as_tinternal_mut(&mut self) -> RefMut<TypedThunkInternal> {
+ self.0.borrow_mut()
+ }
+ fn as_internal(&self) -> Ref<ThunkInternal> {
+ Ref::map(self.as_tinternal(), TypedThunkInternal::as_internal)
+ }
+ fn as_internal_mut(&self) -> RefMut<ThunkInternal> {
+ RefMut::map(self.0.borrow_mut(), TypedThunkInternal::as_internal_mut)
+ }
+
fn do_normalize_whnf(&self) {
- let borrow = self.0.borrow();
+ let borrow = self.as_internal();
match &*borrow {
ThunkInternal::PartialExpr(_) => {
drop(borrow);
- self.0.borrow_mut().normalize_whnf();
+ self.as_internal_mut().normalize_whnf();
}
// Already at least in WHNF
ThunkInternal::ValueF(_, _) => {}
@@ -130,11 +181,11 @@ impl Thunk {
}
fn do_normalize_nf(&self) {
- let borrow = self.0.borrow();
+ let borrow = self.as_internal();
match &*borrow {
ThunkInternal::PartialExpr(_) | ThunkInternal::ValueF(WHNF, _) => {
drop(borrow);
- self.0.borrow_mut().normalize_nf();
+ self.as_internal_mut().normalize_nf();
}
// Already in NF
ThunkInternal::ValueF(NF, _) => {}
@@ -145,14 +196,14 @@ impl Thunk {
// or you could run into BorrowMut panics
pub(crate) fn normalize_nf(&self) -> Ref<ValueF> {
self.do_normalize_nf();
- Ref::map(self.0.borrow(), ThunkInternal::as_nf)
+ Ref::map(self.as_internal(), ThunkInternal::as_nf)
}
// WARNING: avoid normalizing any thunk while holding on to this ref
// or you could run into BorrowMut panics
pub(crate) fn as_valuef(&self) -> Ref<ValueF> {
self.do_normalize_whnf();
- Ref::map(self.0.borrow(), ThunkInternal::as_whnf)
+ Ref::map(self.as_internal(), ThunkInternal::as_whnf)
}
pub(crate) fn to_valuef(&self) -> ValueF {
@@ -173,6 +224,10 @@ impl Thunk {
pub(crate) fn app_thunk(&self, th: Thunk) -> ValueF {
apply_any(self.clone(), th)
}
+
+ pub(crate) fn get_type(&self) -> Result<Cow<'_, Type>, TypeError> {
+ Ok(Cow::Owned(self.as_tinternal().get_type()?))
+ }
}
impl TypedThunk {
@@ -185,9 +240,7 @@ impl TypedThunk {
}
pub(crate) fn normalize_nf(&self) -> ValueF {
- match self {
- TypedThunk(thunk) => thunk.normalize_nf().clone(),
- }
+ self.0.normalize_nf().clone()
}
pub(crate) fn to_typed(&self) -> Typed {
@@ -217,10 +270,7 @@ impl TypedThunk {
}
}
pub(crate) fn from_valuef_and_type(v: ValueF, t: Type) -> Self {
- TypedThunk::from_thunk_and_type(
- Thunk::from_valuef_and_type(v, t.clone()),
- t,
- )
+ TypedThunk(Thunk::from_valuef_and_type(v, t))
}
pub(crate) fn to_valuef(&self) -> ValueF {
@@ -254,19 +304,13 @@ impl TypedThunk {
}
pub(crate) fn get_type(&self) -> Result<Cow<'_, Type>, TypeError> {
- match &(self.0).1 {
- Some(t) => Ok(Cow::Borrowed(&*t)),
- None => Err(TypeError::new(
- &TypecheckContext::new(),
- TypeMessage::Untyped,
- )),
- }
+ self.0.get_type()
}
}
impl Shift for Thunk {
fn shift(&self, delta: isize, var: &AlphaVar) -> Option<Self> {
- Some(Thunk(self.0.shift(delta, var)?, self.1.shift(delta, var)?))
+ Some(Thunk(self.0.shift(delta, var)?))
}
}
@@ -285,15 +329,22 @@ impl Shift for ThunkInternal {
impl Shift for TypedThunk {
fn shift(&self, delta: isize, var: &AlphaVar) -> Option<Self> {
- Some(match self {
- TypedThunk(th) => TypedThunk(th.shift(delta, var)?),
+ Some(TypedThunk(self.0.shift(delta, var)?))
+ }
+}
+
+impl Shift for TypedThunkInternal {
+ fn shift(&self, delta: isize, var: &AlphaVar) -> Option<Self> {
+ Some(TypedThunkInternal {
+ internal: self.internal.shift(delta, var)?,
+ typ: self.typ.shift(delta, var)?,
})
}
}
impl Subst<Typed> for Thunk {
fn subst_shift(&self, var: &AlphaVar, val: &Typed) -> Self {
- Thunk(self.0.subst_shift(var, val), self.1.subst_shift(var, val))
+ Thunk(self.0.subst_shift(var, val))
}
}
@@ -311,14 +362,21 @@ impl Subst<Typed> for ThunkInternal {
}
}
-impl Subst<Typed> for TypedThunk {
+impl Subst<Typed> for TypedThunkInternal {
fn subst_shift(&self, var: &AlphaVar, val: &Typed) -> Self {
- match self {
- TypedThunk(th) => TypedThunk(th.subst_shift(var, val)),
+ TypedThunkInternal {
+ internal: self.internal.subst_shift(var, val),
+ typ: self.typ.subst_shift(var, val),
}
}
}
+impl Subst<Typed> for TypedThunk {
+ fn subst_shift(&self, var: &AlphaVar, val: &Typed) -> Self {
+ TypedThunk(self.0.subst_shift(var, val))
+ }
+}
+
impl std::cmp::PartialEq for Thunk {
fn eq(&self, other: &Self) -> bool {
*self.as_valuef() == *other.as_valuef()
@@ -335,7 +393,7 @@ impl std::cmp::Eq for TypedThunk {}
impl std::fmt::Debug for Thunk {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
- let b: &ThunkInternal = &self.0.borrow();
+ let b: &ThunkInternal = &self.as_internal();
match b {
ThunkInternal::ValueF(m, v) => {
f.debug_tuple(&format!("Thunk@{:?}", m)).field(v).finish()
diff --git a/dhall/src/core/var.rs b/dhall/src/core/var.rs
index 8d02171..ce4d137 100644
--- a/dhall/src/core/var.rs
+++ b/dhall/src/core/var.rs
@@ -157,6 +157,12 @@ impl Shift for () {
}
}
+impl<A: Shift, B: Shift> Shift for (A, B) {
+ fn shift(&self, delta: isize, var: &AlphaVar) -> Option<Self> {
+ Some((self.0.shift(delta, var)?, self.1.shift(delta, var)?))
+ }
+}
+
impl<T: Shift> Shift for Option<T> {
fn shift(&self, delta: isize, var: &AlphaVar) -> Option<Self> {
Some(match self {
@@ -230,6 +236,12 @@ impl<S> Subst<S> for () {
fn subst_shift(&self, _var: &AlphaVar, _val: &S) -> Self {}
}
+impl<S, A: Subst<S>, B: Subst<S>> Subst<S> for (A, B) {
+ fn subst_shift(&self, var: &AlphaVar, val: &S) -> Self {
+ (self.0.subst_shift(var, val), self.1.subst_shift(var, val))
+ }
+}
+
impl<S, T: Subst<S>> Subst<S> for Option<T> {
fn subst_shift(&self, var: &AlphaVar, val: &S) -> Self {
self.as_ref().map(|x| x.subst_shift(var, val))
generated by cgit v1.2.3 (git 2.25.1) at 2024-12-26 21:11:59 +0000