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
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
|
//! This module implements the backing representation of runtime
//! values in the Nix language.
use std::rc::Rc;
use std::{fmt::Display, path::PathBuf};
mod attrs;
mod list;
mod string;
use crate::errors::{Error, EvalResult};
pub use attrs::NixAttrs;
pub use list::NixList;
pub use string::NixString;
#[derive(Clone, Debug)]
pub enum Value {
Null,
Bool(bool),
Integer(i64),
Float(f64),
String(NixString),
Path(PathBuf),
Attrs(Rc<NixAttrs>),
List(NixList),
// Internal values that, while they technically exist at runtime,
// are never returned to or created directly by users.
AttrPath(Vec<NixString>),
Blackhole,
NotFound,
}
impl Value {
pub fn is_number(&self) -> bool {
match self {
Value::Integer(_) => true,
Value::Float(_) => true,
_ => false,
}
}
pub fn type_of(&self) -> &'static str {
match self {
Value::Null => "null",
Value::Bool(_) => "bool",
Value::Integer(_) => "int",
Value::Float(_) => "float",
Value::String(_) => "string",
Value::Path(_) => "path",
Value::Attrs(_) => "set",
Value::List(_) => "list",
// Internal types
Value::AttrPath(_) | Value::Blackhole | Value::NotFound => "internal",
}
}
pub fn as_bool(&self) -> EvalResult<bool> {
match self {
Value::Bool(b) => Ok(*b),
other => Err(Error::TypeError {
expected: "bool",
actual: other.type_of(),
}),
}
}
pub fn as_string(self) -> EvalResult<NixString> {
match self {
Value::String(s) => Ok(s),
other => Err(Error::TypeError {
expected: "string",
actual: other.type_of(),
}),
}
}
pub fn as_attrs(self) -> EvalResult<Rc<NixAttrs>> {
match self {
Value::Attrs(s) => Ok(s),
other => Err(Error::TypeError {
expected: "set",
actual: other.type_of(),
}),
}
}
pub fn as_list(self) -> EvalResult<NixList> {
match self {
Value::List(l) => Ok(l),
other => Err(Error::TypeError {
expected: "list",
actual: other.type_of(),
}),
}
}
pub fn is_bool(&self) -> bool {
matches!(self, Value::Bool(_))
}
}
impl Display for Value {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
match self {
Value::Null => f.write_str("null"),
Value::Bool(true) => f.write_str("true"),
Value::Bool(false) => f.write_str("false"),
Value::Integer(num) => write!(f, "{}", num),
Value::String(s) => s.fmt(f),
Value::Path(p) => p.display().fmt(f),
Value::Attrs(attrs) => attrs.fmt(f),
Value::List(list) => list.fmt(f),
// Nix prints floats with a maximum precision of 5 digits
// only.
Value::Float(num) => {
write!(f, "{}", format!("{:.5}", num).trim_end_matches(['.', '0']))
}
// internal types
Value::AttrPath(_) => f.write_str("internal[attrpath]"),
Value::Blackhole => f.write_str("internal[blackhole]"),
Value::NotFound => f.write_str("internal[not found]"),
}
}
}
impl PartialEq for Value {
fn eq(&self, other: &Self) -> bool {
match (self, other) {
// Trivial comparisons
(Value::Null, Value::Null) => true,
(Value::Bool(b1), Value::Bool(b2)) => b1 == b2,
(Value::List(l1), Value::List(l2)) => l1 == l2,
(Value::String(s1), Value::String(s2)) => s1 == s2,
// Numerical comparisons (they work between float & int)
(Value::Integer(i1), Value::Integer(i2)) => i1 == i2,
(Value::Integer(i), Value::Float(f)) => *i as f64 == *f,
(Value::Float(f1), Value::Float(f2)) => f1 == f2,
(Value::Float(f), Value::Integer(i)) => *i as f64 == *f,
// Optimised attribute set comparison
(Value::Attrs(a1), Value::Attrs(a2)) => Rc::ptr_eq(a1, a2) || { a1 == a2 },
// Everything else is either incomparable (e.g. internal
// types) or false.
_ => false,
}
}
}
|
