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//! This module implements the runtime representation of functions.
use std::{collections::HashMap, hash::Hash, rc::Rc};
use codemap::Span;
use smol_str::SmolStr;
use crate::{chunk::Chunk, upvalues::Upvalues};
use super::NixString;
#[derive(Clone, Debug, PartialEq)]
pub(crate) struct Formals {
/// Map from argument name, to whether that argument is required
pub(crate) arguments: HashMap<NixString, bool>,
/// Do the formals of this function accept extra arguments
pub(crate) ellipsis: bool,
/// The span of the formals themselves, to use to emit errors
pub(crate) span: Span,
}
impl Formals {
/// Returns true if the given arg is a valid argument to these formals.
///
/// This is true if it is either listed in the list of arguments, or the formals have an
/// ellipsis
pub(crate) fn contains<Q>(&self, arg: &Q) -> bool
where
Q: ?Sized + Hash + Eq,
NixString: std::borrow::Borrow<Q>,
{
self.ellipsis || self.arguments.contains_key(&arg)
}
}
/// The opcodes for a thunk or closure, plus the number of
/// non-executable opcodes which are allowed after an OpThunkClosure or
/// OpThunkSuspended referencing it. At runtime `Lambda` is usually wrapped
/// in `Rc` to avoid copying the `Chunk` it holds (which can be
/// quite large).
#[derive(Debug, Default)]
pub struct Lambda {
pub(crate) chunk: Chunk,
/// Name of the function (equivalent to the name of the
/// identifier (e.g. a value in a let-expression or an attribute
/// set entry) it is located in).
pub(crate) name: Option<SmolStr>,
/// Number of upvalues which the code in this Lambda closes
/// over, and which need to be initialised at
/// runtime. Information about the variables is emitted using
/// data-carrying opcodes (see [`OpCode::DataStackIdx`]).
pub(crate) upvalue_count: usize,
pub(crate) formals: Option<Formals>,
}
impl Lambda {
pub fn chunk(&mut self) -> &mut Chunk {
&mut self.chunk
}
}
#[derive(Clone, Debug)]
pub struct Closure {
pub lambda: Rc<Lambda>,
pub upvalues: Rc<Upvalues>,
/// true if all upvalues have been realised
#[cfg(debug_assertions)]
pub is_finalised: bool,
}
impl Closure {
pub fn new(lambda: Rc<Lambda>) -> Self {
Self::new_with_upvalues(
Rc::new(Upvalues::with_capacity(lambda.upvalue_count)),
lambda,
)
}
/// Do not call this function unless you have read
/// `tvix/docs/value-pointer-equality.md` carefully.
pub fn ptr_eq(&self, other: &Self) -> bool {
Rc::ptr_eq(&self.lambda, &other.lambda) && Rc::ptr_eq(&self.upvalues, &other.upvalues)
}
pub fn new_with_upvalues(upvalues: Rc<Upvalues>, lambda: Rc<Lambda>) -> Self {
Closure {
upvalues,
lambda,
#[cfg(debug_assertions)]
is_finalised: true,
}
}
pub fn chunk(&self) -> &Chunk {
&self.lambda.chunk
}
pub fn lambda(&self) -> Rc<Lambda> {
self.lambda.clone()
}
pub fn upvalues(&self) -> &Upvalues {
&self.upvalues
}
}
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