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-rw-r--r--dhall/src/core/context.rs51
1 files changed, 37 insertions, 14 deletions
diff --git a/dhall/src/core/context.rs b/dhall/src/core/context.rs
index 56dec03..73ad516 100644
--- a/dhall/src/core/context.rs
+++ b/dhall/src/core/context.rs
@@ -1,6 +1,5 @@
use std::rc::Rc;
-use dhall_syntax::context::Context as SimpleContext;
use dhall_syntax::{Label, V};
use crate::core::thunk::Thunk;
@@ -16,7 +15,7 @@ pub(crate) enum CtxItem<T> {
}
#[derive(Debug, Clone)]
-pub(crate) struct Context<T>(Rc<SimpleContext<Label, CtxItem<T>>>);
+pub(crate) struct Context<T>(Rc<Vec<(Label, CtxItem<T>)>>);
#[derive(Debug, Clone)]
pub(crate) struct NormalizationContext(Context<()>);
@@ -26,26 +25,40 @@ pub(crate) struct TypecheckContext(Context<Type>);
impl<T> Context<T> {
pub(crate) fn new() -> Self {
- Context(Rc::new(SimpleContext::new()))
+ Context(Rc::new(Vec::new()))
}
pub(crate) fn insert_kept(&self, x: &Label, t: T) -> Self
where
T: Shift + Clone,
{
- Context(Rc::new(self.0.map(|_, e| e.shift(1, &x.into())).insert(
- x.clone(),
- CtxItem::Kept(x.into(), t.shift(1, &x.into())),
- )))
- }
- pub(crate) fn insert_replaced(&self, x: &Label, e: Thunk, t: T) -> Self
+ let mut vec: Vec<_> = self
+ .0
+ .iter()
+ .map(|(l, i)| (l.clone(), i.shift(1, &x.into())))
+ .collect();
+ vec.push((x.clone(), CtxItem::Kept(x.into(), t.shift(1, &x.into()))));
+ Context(Rc::new(vec))
+ }
+ pub(crate) fn insert_replaced(&self, x: &Label, th: Thunk, t: T) -> Self
where
T: Clone,
{
- Context(Rc::new(self.0.insert(x.clone(), CtxItem::Replaced(e, t))))
+ let mut vec = self.0.as_ref().clone();
+ vec.push((x.clone(), CtxItem::Replaced(th, t)));
+ Context(Rc::new(vec))
}
pub(crate) fn lookup(&self, var: &V<Label>) -> Option<&CtxItem<T>> {
- let V(x, n) = var;
- self.0.lookup(x, *n)
+ let V(x, mut n) = var;
+ for (l, i) in self.0.iter().rev() {
+ if x == l {
+ if n == 0 {
+ return Some(i);
+ } else {
+ n -= 1;
+ }
+ }
+ }
+ None
}
}
@@ -113,7 +126,12 @@ impl<T: Shift> Shift for CtxItem<T> {
impl<T: Shift> Shift for Context<T> {
fn shift(&self, delta: isize, var: &AlphaVar) -> Self {
- Context(Rc::new(self.0.map(|_, e| e.shift(delta, var))))
+ Context(Rc::new(
+ self.0
+ .iter()
+ .map(|(l, i)| (l.clone(), i.shift(delta, var)))
+ .collect(),
+ ))
}
}
@@ -142,7 +160,12 @@ impl<T: Subst<Typed>> Subst<Typed> for CtxItem<T> {
impl<T: Subst<Typed>> Subst<Typed> for Context<T> {
fn subst_shift(&self, var: &AlphaVar, val: &Typed) -> Self {
- Context(Rc::new(self.0.map(|_, e| e.subst_shift(var, val))))
+ Context(Rc::new(
+ self.0
+ .iter()
+ .map(|(l, i)| (l.clone(), i.subst_shift(var, val)))
+ .collect(),
+ ))
}
}