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
83
84

use crate::{Env, Value, Result};

pub use {user_ptr::Transfer, vector::Vector};

mod integer;
mod float;
mod string;
mod user_ptr;
mod vector;

// XXX: More accurate would be `CloneFromLisp` or `Decode`, but ...
/// Converting Lisp [`Value`] into a Rust type.
///
/// # Implementation
///
/// The lifetime parameter is put on the trait itself, instead of the method. This allows it to be
/// implemented for [`Value`] itself.
///
/// [`Value`]: struct.Value.html
pub trait FromLisp<'e>: Sized {
    fn from_lisp(value: Value<'e>) -> Result<Self>;
}

// XXX: More accurate would be `CloneToLisp`, `Encode`, but ...
/// Converting a Rust type into Lisp [`Value`].
///
/// # Implementation
///
/// The lifetime parameter is put on the trait itself, instead of the method. This allows the impl
/// for [`Value`] to simply return the input, instead of having to create a new [`Value`].
///
/// [`Value`]: struct.Value.html
pub trait IntoLisp<'e> {
    fn into_lisp(self, env: &'e Env) -> Result<Value<'e>>;
}

impl<'a, 'e: 'a> FromLisp<'e> for Value<'a> {
    #[inline(always)]
    fn from_lisp(value: Value<'e>) -> Result<Value<'a>> {
        Ok(value)
    }
}

impl<'e> IntoLisp<'e> for Value<'e> {
    #[inline(always)]
    fn into_lisp(self, _: &'e Env) -> Result<Value<'_>> {
        Ok(self)
    }
}

impl<'e, T: FromLisp<'e>> FromLisp<'e> for Option<T> {
    fn from_lisp(value: Value<'e>) -> Result<Self> {
        if value.is_not_nil() {
            Ok(Some(<T as FromLisp>::from_lisp(value)?))
        } else {
            Ok(None)
        }
    }
}

impl<'e, T: IntoLisp<'e>> IntoLisp<'e> for Option<T> {
    fn into_lisp(self, env: &'e Env) -> Result<Value<'_>> {
        match self {
            Some(t) => t.into_lisp(env),
            None => env.intern("nil"),
        }
    }
}

impl IntoLisp<'_> for () {
    fn into_lisp(self, env: &Env) -> Result<Value<'_>> {
        env.intern("nil")
    }
}

impl IntoLisp<'_> for bool {
    fn into_lisp(self, env: &Env) -> Result<Value<'_>> {
        if self {
            env.intern("t")
        } else {
            env.intern("nil")
        }
    }
}