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|
//! This module implements Nix lists.
use std::ops::Index;
use imbl::{vector, Vector};
use serde::{Deserialize, Serialize};
use crate::errors::AddContext;
use crate::errors::ErrorKind;
use crate::vm::generators;
use crate::vm::generators::GenCo;
use crate::vm::VM;
use super::thunk::ThunkSet;
use super::TotalDisplay;
use super::Value;
#[repr(transparent)]
#[derive(Clone, Debug, Deserialize, Serialize)]
pub struct NixList(Vector<Value>);
impl TotalDisplay for NixList {
fn total_fmt(&self, f: &mut std::fmt::Formatter<'_>, set: &mut ThunkSet) -> std::fmt::Result {
f.write_str("[ ")?;
for v in self {
v.total_fmt(f, set)?;
f.write_str(" ")?;
}
f.write_str("]")
}
}
impl From<Vector<Value>> for NixList {
fn from(vs: Vector<Value>) -> Self {
Self(vs)
}
}
impl NixList {
pub fn len(&self) -> usize {
self.0.len()
}
pub fn get(&self, i: usize) -> Option<&Value> {
self.0.get(i)
}
pub fn is_empty(&self) -> bool {
self.0.is_empty()
}
pub fn construct(count: usize, stack_slice: Vec<Value>) -> Self {
debug_assert!(
count == stack_slice.len(),
"NixList::construct called with count == {}, but slice.len() == {}",
count,
stack_slice.len(),
);
NixList(Vector::from_iter(stack_slice.into_iter()))
}
pub fn iter(&self) -> vector::Iter<Value> {
self.0.iter()
}
pub fn ptr_eq(&self, other: &Self) -> bool {
self.0.ptr_eq(&other.0)
}
/// Compare `self` against `other` for equality using Nix equality semantics
pub fn nix_eq(&self, other: &Self, vm: &mut VM) -> Result<bool, ErrorKind> {
if self.ptr_eq(other) {
return Ok(true);
}
if self.len() != other.len() {
return Ok(false);
}
for (v1, v2) in self.iter().zip(other.iter()) {
if !v1.nix_eq(v2, vm)? {
return Ok(false);
}
}
Ok(true)
}
/// force each element of the list (shallowly), making it safe to call .get().value()
pub fn force_elements(&self, vm: &mut VM) -> Result<(), ErrorKind> {
self.iter().try_for_each(|v| v.force(vm).map(|_| ()))
}
pub fn into_inner(self) -> Vector<Value> {
self.0
}
#[deprecated(note = "callers should avoid constructing from Vec")]
pub fn from_vec(vs: Vec<Value>) -> Self {
Self(Vector::from_iter(vs.into_iter()))
}
/// Asynchronous sorting algorithm in which the comparator can make use of
/// VM requests (required as `builtins.sort` uses comparators written in
/// Nix).
///
/// This is a simple, optimised bubble sort implementation. The choice of
/// algorithm is constrained by the comparator in Nix not being able to
/// yield equality, and us being unable to use the standard library
/// implementation of sorting (which is a lot longer, but a lot more
/// efficient) here.
// TODO(amjoseph): Investigate potential impl in Nix code, or Tvix bytecode.
pub async fn sort_by(&mut self, co: &GenCo, cmp: Value) -> Result<(), ErrorKind> {
let mut len = self.len();
loop {
let mut new_len = 0;
for i in 1..len {
if generators::request_force(
co,
generators::request_call_with(
co,
cmp.clone(),
[self.0[i].clone(), self.0[i - 1].clone()],
)
.await,
)
.await
.as_bool()
.context("evaluating comparator in `builtins.sort`")?
{
self.0.swap(i, i - 1);
new_len = i;
}
}
if new_len == 0 {
break;
}
len = new_len;
}
Ok(())
}
}
impl IntoIterator for NixList {
type Item = Value;
type IntoIter = imbl::vector::ConsumingIter<Value>;
fn into_iter(self) -> Self::IntoIter {
self.0.into_iter()
}
}
impl<'a> IntoIterator for &'a NixList {
type Item = &'a Value;
type IntoIter = imbl::vector::Iter<'a, Value>;
fn into_iter(self) -> Self::IntoIter {
self.0.iter()
}
}
impl Index<usize> for NixList {
type Output = Value;
fn index(&self, index: usize) -> &Self::Output {
&self.0[index]
}
}
|
