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-rw-r--r--dhall/src/core/thunk.rs312
1 files changed, 0 insertions, 312 deletions
diff --git a/dhall/src/core/thunk.rs b/dhall/src/core/thunk.rs
deleted file mode 100644
index f41579c..0000000
--- a/dhall/src/core/thunk.rs
+++ /dev/null
@@ -1,312 +0,0 @@
-use std::cell::{Ref, RefCell};
-use std::rc::Rc;
-
-use dhall_syntax::{ExprF, X};
-
-use crate::core::context::NormalizationContext;
-use crate::core::value::Value;
-use crate::core::var::{AlphaVar, Shift, Subst};
-use crate::phase::normalize::{
- apply_any, normalize_one_layer, normalize_whnf, InputSubExpr, OutputSubExpr,
-};
-use crate::phase::{Type, Typed};
-
-#[derive(Debug, Clone, Copy)]
-enum Marker {
- /// Weak Head Normal Form, i.e. subexpressions may not be normalized
- WHNF,
- /// Normal form, i.e. completely normalized
- NF,
-}
-use Marker::{NF, WHNF};
-
-#[derive(Debug)]
-enum ThunkInternal {
- /// Non-normalized value alongside a normalization context
- Unnormalized(NormalizationContext, InputSubExpr),
- /// Partially normalized value whose subexpressions have been thunked (this is returned from
- /// typechecking). Note that this is different from `Value::PartialExpr` because there is no
- /// requirement of WHNF here.
- PartialExpr(ExprF<Thunk, X>),
- /// Partially normalized value.
- /// Invariant: if the marker is `NF`, the value must be fully normalized
- Value(Marker, Value),
-}
-
-/// Stores a possibly unevaluated value. Gets (partially) normalized on-demand,
-/// sharing computation automatically.
-/// Uses a RefCell to share computation.
-#[derive(Debug, Clone)]
-pub struct Thunk(Rc<RefCell<ThunkInternal>>);
-
-/// A thunk in type position. Can optionally store a Type from the typechecking phase to preserve
-/// type information through the normalization phase.
-#[derive(Debug, Clone)]
-pub struct TypeThunk(Typed);
-
-impl ThunkInternal {
- fn into_thunk(self) -> Thunk {
- Thunk(Rc::new(RefCell::new(self)))
- }
-
- fn normalize_whnf(&mut self) {
- match self {
- ThunkInternal::Unnormalized(ctx, e) => {
- *self = ThunkInternal::Value(
- WHNF,
- normalize_whnf(ctx.clone(), e.clone()),
- )
- }
- ThunkInternal::PartialExpr(e) => {
- *self =
- ThunkInternal::Value(WHNF, normalize_one_layer(e.clone()))
- }
- // Already at least in WHNF
- ThunkInternal::Value(_, _) => {}
- }
- }
-
- fn normalize_nf(&mut self) {
- match self {
- ThunkInternal::Unnormalized(_, _)
- | ThunkInternal::PartialExpr(_) => {
- self.normalize_whnf();
- self.normalize_nf();
- }
- ThunkInternal::Value(m @ WHNF, v) => {
- v.normalize_mut();
- *m = NF;
- }
- // Already in NF
- ThunkInternal::Value(NF, _) => {}
- }
- }
-
- // Always use normalize_whnf before
- fn as_whnf(&self) -> &Value {
- match self {
- ThunkInternal::Unnormalized(_, _)
- | ThunkInternal::PartialExpr(_) => unreachable!(),
- ThunkInternal::Value(_, v) => v,
- }
- }
-
- // Always use normalize_nf before
- fn as_nf(&self) -> &Value {
- match self {
- ThunkInternal::Unnormalized(_, _)
- | ThunkInternal::PartialExpr(_)
- | ThunkInternal::Value(WHNF, _) => unreachable!(),
- ThunkInternal::Value(NF, v) => v,
- }
- }
-}
-
-impl Thunk {
- pub fn new(ctx: NormalizationContext, e: InputSubExpr) -> Thunk {
- ThunkInternal::Unnormalized(ctx, e).into_thunk()
- }
-
- pub fn from_value(v: Value) -> Thunk {
- ThunkInternal::Value(WHNF, v).into_thunk()
- }
-
- pub fn from_partial_expr(e: ExprF<Thunk, X>) -> Thunk {
- ThunkInternal::PartialExpr(e).into_thunk()
- }
-
- // Normalizes contents to normal form; faster than `normalize_nf` if
- // no one else shares this thunk
- pub fn normalize_mut(&mut self) {
- match Rc::get_mut(&mut self.0) {
- // Mutate directly if sole owner
- Some(refcell) => RefCell::get_mut(refcell).normalize_nf(),
- // Otherwise mutate through the refcell
- None => self.0.borrow_mut().normalize_nf(),
- }
- }
-
- fn do_normalize_whnf(&self) {
- let borrow = self.0.borrow();
- match &*borrow {
- ThunkInternal::Unnormalized(_, _)
- | ThunkInternal::PartialExpr(_) => {
- drop(borrow);
- self.0.borrow_mut().normalize_whnf();
- }
- // Already at least in WHNF
- ThunkInternal::Value(_, _) => {}
- }
- }
-
- fn do_normalize_nf(&self) {
- let borrow = self.0.borrow();
- match &*borrow {
- ThunkInternal::Unnormalized(_, _)
- | ThunkInternal::PartialExpr(_)
- | ThunkInternal::Value(WHNF, _) => {
- drop(borrow);
- self.0.borrow_mut().normalize_nf();
- }
- // Already in NF
- ThunkInternal::Value(NF, _) => {}
- }
- }
-
- // WARNING: avoid normalizing any thunk while holding on to this ref
- // or you could run into BorrowMut panics
- pub fn normalize_nf(&self) -> Ref<Value> {
- self.do_normalize_nf();
- Ref::map(self.0.borrow(), ThunkInternal::as_nf)
- }
-
- // WARNING: avoid normalizing any thunk while holding on to this ref
- // or you could run into BorrowMut panics
- pub fn as_value(&self) -> Ref<Value> {
- self.do_normalize_whnf();
- Ref::map(self.0.borrow(), ThunkInternal::as_whnf)
- }
-
- pub fn to_value(&self) -> Value {
- self.as_value().clone()
- }
-
- pub fn normalize_to_expr_maybe_alpha(&self, alpha: bool) -> OutputSubExpr {
- self.normalize_nf().normalize_to_expr_maybe_alpha(alpha)
- }
-
- pub fn app_val(&self, val: Value) -> Value {
- self.app_thunk(val.into_thunk())
- }
-
- pub fn app_thunk(&self, th: Thunk) -> Value {
- apply_any(self.clone(), th)
- }
-}
-
-impl TypeThunk {
- pub fn from_value(v: Value) -> TypeThunk {
- TypeThunk::from_thunk(Thunk::from_value(v))
- }
-
- pub fn from_thunk(th: Thunk) -> TypeThunk {
- TypeThunk(Typed::from_thunk_untyped(th))
- }
-
- pub fn from_type(t: Type) -> TypeThunk {
- TypeThunk(t)
- }
-
- pub fn normalize_mut(&mut self) {
- self.0.normalize_mut()
- }
-
- pub fn normalize_nf(&self) -> Value {
- self.0.to_value().normalize()
- }
-
- pub fn to_value(&self) -> Value {
- self.0.to_value()
- }
-
- pub fn to_thunk(&self) -> Thunk {
- self.0.to_thunk()
- }
-
- pub fn to_type(&self) -> Type {
- self.0.to_type()
- }
-
- pub fn to_typed(&self) -> Typed {
- self.0.clone()
- }
-
- pub fn normalize_to_expr_maybe_alpha(&self, alpha: bool) -> OutputSubExpr {
- self.normalize_nf().normalize_to_expr_maybe_alpha(alpha)
- }
-}
-
-impl Shift for Thunk {
- fn shift(&self, delta: isize, var: &AlphaVar) -> Option<Self> {
- Some(self.0.borrow().shift(delta, var)?.into_thunk())
- }
-}
-
-impl Shift for ThunkInternal {
- fn shift(&self, delta: isize, var: &AlphaVar) -> Option<Self> {
- Some(match self {
- ThunkInternal::Unnormalized(ctx, e) => {
- ThunkInternal::Unnormalized(ctx.shift(delta, var)?, e.clone())
- }
- ThunkInternal::PartialExpr(e) => ThunkInternal::PartialExpr(
- e.traverse_ref_with_special_handling_of_binders(
- |v| Ok(v.shift(delta, var)?),
- |x, v| Ok(v.shift(delta, &var.under_binder(x))?),
- |x| Ok(X::clone(x)),
- )?,
- ),
- ThunkInternal::Value(m, v) => {
- ThunkInternal::Value(*m, v.shift(delta, var)?)
- }
- })
- }
-}
-
-impl Shift for TypeThunk {
- fn shift(&self, delta: isize, var: &AlphaVar) -> Option<Self> {
- Some(TypeThunk(self.0.shift(delta, var)?))
- }
-}
-
-impl Subst<Typed> for Thunk {
- fn subst_shift(&self, var: &AlphaVar, val: &Typed) -> Self {
- self.0.borrow().subst_shift(var, val).into_thunk()
- }
-}
-
-impl Subst<Typed> for ThunkInternal {
- fn subst_shift(&self, var: &AlphaVar, val: &Typed) -> Self {
- match self {
- ThunkInternal::Unnormalized(ctx, e) => ThunkInternal::Unnormalized(
- ctx.subst_shift(var, val),
- e.clone(),
- ),
- ThunkInternal::PartialExpr(e) => ThunkInternal::PartialExpr(
- e.map_ref_with_special_handling_of_binders(
- |v| v.subst_shift(var, val),
- |x, v| {
- v.subst_shift(
- &var.under_binder(x),
- &val.under_binder(x),
- )
- },
- X::clone,
- ),
- ),
- ThunkInternal::Value(_, v) => {
- // The resulting value may not stay in normal form after substitution
- ThunkInternal::Value(WHNF, v.subst_shift(var, val))
- }
- }
- }
-}
-
-impl Subst<Typed> for TypeThunk {
- fn subst_shift(&self, var: &AlphaVar, val: &Typed) -> Self {
- TypeThunk(self.0.subst_shift(var, val))
- }
-}
-
-impl std::cmp::PartialEq for Thunk {
- fn eq(&self, other: &Self) -> bool {
- *self.as_value() == *other.as_value()
- }
-}
-impl std::cmp::Eq for Thunk {}
-
-impl std::cmp::PartialEq for TypeThunk {
- fn eq(&self, other: &Self) -> bool {
- self.to_value() == other.to_value()
- }
-}
-impl std::cmp::Eq for TypeThunk {}
generated by cgit v1.2.3 (git 2.25.1) at 2024-07-05 02:42:44 +0000