//! 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 } }