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authorNadrieril2020-01-29 21:56:52 +0000
committerNadrieril2020-01-29 21:56:52 +0000
commit489174a426e6057a68b6edd2e9b4387d09912a25 (patch)
treedc73718183a78548ef018e5dc0ac040d09f15c19 /dhall/src/semantics/nze/nzexpr.rs
parent280b3174476ef8fe5a98f3614f4fe253fa243d8c (diff)
Move envs to their own files
Diffstat (limited to 'dhall/src/semantics/nze/nzexpr.rs')
-rw-r--r--dhall/src/semantics/nze/nzexpr.rs116
1 files changed, 0 insertions, 116 deletions
diff --git a/dhall/src/semantics/nze/nzexpr.rs b/dhall/src/semantics/nze/nzexpr.rs
deleted file mode 100644
index c065a5b..0000000
--- a/dhall/src/semantics/nze/nzexpr.rs
+++ /dev/null
@@ -1,116 +0,0 @@
-use crate::semantics::core::var::AlphaVar;
-use crate::syntax::{Label, V};
-
-pub(crate) type Binder = Label;
-
-#[derive(Debug, Clone)]
-pub(crate) struct NameEnv {
- names: Vec<Binder>,
-}
-
-#[derive(Debug, Clone, Copy)]
-pub(crate) struct VarEnv {
- size: usize,
-}
-
-#[derive(Debug, Clone, Copy, PartialEq, Eq)]
-pub(crate) enum NzVar {
- /// Reverse-debruijn index: counts number of binders from the bottom of the stack.
- Bound(usize),
- /// Fake fresh variable generated for expression equality checking.
- Fresh(usize),
-}
-
-impl NameEnv {
- pub fn new() -> Self {
- NameEnv { names: Vec::new() }
- }
- pub fn from_binders(names: impl Iterator<Item = Binder>) -> Self {
- NameEnv {
- names: names.collect(),
- }
- }
- pub fn as_varenv(&self) -> VarEnv {
- VarEnv {
- size: self.names.len(),
- }
- }
-
- pub fn insert(&self, x: &Binder) -> Self {
- let mut env = self.clone();
- env.insert_mut(x);
- env
- }
- pub fn insert_mut(&mut self, x: &Binder) {
- self.names.push(x.clone())
- }
- pub fn remove_mut(&mut self) {
- self.names.pop();
- }
-
- pub fn unlabel_var(&self, var: &V<Binder>) -> Option<AlphaVar> {
- let V(name, idx) = var;
- let (idx, _) = self
- .names
- .iter()
- .rev()
- .enumerate()
- .filter(|(_, n)| *n == name)
- .nth(*idx)?;
- Some(AlphaVar::new(V((), idx)))
- }
- pub fn label_var(&self, var: &AlphaVar) -> V<Binder> {
- let name = &self.names[self.names.len() - 1 - var.idx()];
- let idx = self
- .names
- .iter()
- .rev()
- .take(var.idx())
- .filter(|n| *n == name)
- .count();
- V(name.clone(), idx)
- }
-}
-
-impl VarEnv {
- pub fn new() -> Self {
- VarEnv { size: 0 }
- }
- 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(V((), idx)))
- }
-}
-
-impl NzVar {
- pub fn new(idx: usize) -> Self {
- NzVar::Bound(idx)
- }
- pub fn fresh() -> Self {
- use std::sync::atomic::{AtomicUsize, Ordering};
- // Global counter to ensure uniqueness of the generated id.
- static FRESH_VAR_COUNTER: AtomicUsize = AtomicUsize::new(0);
- let id = FRESH_VAR_COUNTER.fetch_add(1, Ordering::SeqCst);
- NzVar::Fresh(id)
- }
- // Panics on a fresh variable.
- pub fn idx(&self) -> usize {
- match self {
- NzVar::Bound(i) => *i,
- NzVar::Fresh(_) => panic!(
- "Trying to use a fresh variable outside of equality checking"
- ),
- }
- }
-}