about summary refs log tree commit diff
path: root/tvix/eval/src/value/function.rs
blob: 0923e1b1cba90f20bdf96915884f2d1546d87a7e (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
//! This module implements the runtime representation of functions.
use std::{
    cell::{Ref, RefCell, RefMut},
    rc::Rc,
};

use crate::{
    chunk::Chunk,
    upvalues::{UpvalueCarrier, Upvalues},
};

/// The opcodes for a thunk or closure, plus the number of
/// non-executable opcodes which are allowed after an OpClosure or
/// OpThunk referencing it.  At runtime `Lambda` is usually wrapped
/// in `Rc` to avoid copying the `Chunk` it holds (which can be
/// quite large).
#[derive(Debug, PartialEq)]
pub struct Lambda {
    // name: Option<NixString>,
    pub(crate) chunk: Chunk,

    /// 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::DataLocalIdx`]).
    pub(crate) upvalue_count: usize,
}

impl Lambda {
    pub fn new_anonymous() -> Self {
        Lambda {
            // name: None,
            chunk: Default::default(),
            upvalue_count: 0,
        }
    }

    pub fn chunk(&mut self) -> &mut Chunk {
        &mut self.chunk
    }
}

#[derive(Clone, Debug, PartialEq)]
pub struct InnerClosure {
    pub lambda: Rc<Lambda>,
    upvalues: Upvalues,
}

#[repr(transparent)]
#[derive(Clone, Debug, PartialEq)]
pub struct Closure(Rc<RefCell<InnerClosure>>);

impl Closure {
    pub fn new(lambda: Rc<Lambda>) -> Self {
        Closure(Rc::new(RefCell::new(InnerClosure {
            upvalues: Upvalues::with_capacity(lambda.upvalue_count),
            lambda,
        })))
    }

    pub fn chunk(&self) -> Ref<'_, Chunk> {
        Ref::map(self.0.borrow(), |c| &c.lambda.chunk)
    }

    pub fn lambda(&self) -> Rc<Lambda> {
        self.0.borrow().lambda.clone()
    }
}

impl UpvalueCarrier for Closure {
    fn upvalue_count(&self) -> usize {
        self.0.borrow().lambda.upvalue_count
    }

    fn upvalues(&self) -> Ref<'_, Upvalues> {
        Ref::map(self.0.borrow(), |c| &c.upvalues)
    }

    fn upvalues_mut(&self) -> RefMut<'_, Upvalues> {
        RefMut::map(self.0.borrow_mut(), |c| &mut c.upvalues)
    }
}