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use crate::semantics::{AlphaVar, NameEnv, Nir, NzEnv, NzVar, Type, ValEnv};
use crate::syntax::Label;
/// Environment for indexing variables.
#[derive(Debug, Clone, Copy)]
pub(crate) struct VarEnv {
size: usize,
}
/// Environment for typing expressions.
#[derive(Debug, Clone)]
pub(crate) struct TyEnv {
names: NameEnv,
items: ValEnv<Type>,
}
impl VarEnv {
pub fn new() -> Self {
VarEnv { size: 0 }
}
pub fn from_size(size: usize) -> Self {
VarEnv { size }
}
pub fn size(self) -> usize {
self.size
}
pub fn insert(self) -> Self {
VarEnv {
size: self.size + 1,
}
}
pub fn lookup(self, var: NzVar) -> AlphaVar {
self.lookup_fallible(var).unwrap()
}
pub fn lookup_fallible(self, var: NzVar) -> Option<AlphaVar> {
let idx = self.size.checked_sub(var.idx() + 1)?;
Some(AlphaVar::new(idx))
}
}
impl TyEnv {
pub fn new() -> Self {
TyEnv {
names: NameEnv::new(),
items: ValEnv::new(),
}
}
pub fn as_varenv(&self) -> VarEnv {
self.names.as_varenv()
}
pub fn to_nzenv(&self) -> NzEnv {
self.items.discard_types()
}
pub fn as_nameenv(&self) -> &NameEnv {
&self.names
}
pub fn insert_type(&self, x: &Label, ty: Type) -> Self {
TyEnv {
names: self.names.insert(x),
items: self.items.insert_type(ty),
}
}
pub fn insert_value(&self, x: &Label, e: Nir, ty: Type) -> Self {
TyEnv {
names: self.names.insert(x),
items: self.items.insert_value(e, ty),
}
}
pub fn lookup(&self, var: AlphaVar) -> Type {
self.items.lookup_ty(var)
}
}
impl<'a> From<&'a TyEnv> for NzEnv {
fn from(x: &'a TyEnv) -> Self {
x.to_nzenv()
}
}
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