about summary refs log tree commit diff
path: root/tvix/eval/src/builtins/mod.rs
blob: 5b497cde7eb2513ccb0bb42b54c82addca864f25 (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
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
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
//! This module implements the builtins exposed in the Nix language.
//!
//! See //tvix/eval/docs/builtins.md for a some context on the
//! available builtins in Nix.

use std::{
    collections::{BTreeMap, HashMap},
    path::PathBuf,
    rc::Rc,
};

use crate::{
    errors::ErrorKind,
    value::{Builtin, CoercionKind, NixAttrs, NixList, NixString, Value},
    vm::VM,
};

use crate::arithmetic_op;

use self::versions::VersionPartsIter;

pub mod versions;

/// Helper macro to ensure that a value has been forced. The structure
/// of this is a little cumbersome as there are different reference
/// types depending on whether the value is inside a thunk or not.
macro_rules! force {
    ( $vm:ident, $src:expr, $value:ident, $body:block ) => {
        if let Value::Thunk(thunk) = $src {
            thunk.force($vm)?;
            let guard = thunk.value();
            let $value: &Value = &guard;
            $body
        } else {
            let $value: &Value = $src;
            $body
        }
    };

    ( $vm:ident, $value:ident, $body:block ) => {
        force!($vm, &$value, $value, $body)
    };
}

/// Coerce a Nix Value to a plain path, e.g. in order to access the file it
/// points to in an I/O builtin. This coercion can _never_ be performed in
/// a Nix program directly (i.e. the trick `path: /. + path` to convert from
/// a string to a path wouldn't hit this code), so the target file
/// doesn't need to be realised or imported into the Nix store.
pub fn coerce_value_to_path(v: &Value, vm: &mut VM) -> Result<PathBuf, ErrorKind> {
    force!(vm, v, value, {
        match value {
            Value::Thunk(t) => coerce_value_to_path(&t.value(), vm),
            Value::Path(p) => Ok(p.clone()),
            _ => value
                .coerce_to_string(CoercionKind::Weak, vm)
                .map(|s| PathBuf::from(s.as_str()))
                .and_then(|path| {
                    if path.is_absolute() {
                        Ok(path)
                    } else {
                        Err(ErrorKind::NotAnAbsolutePath(path))
                    }
                }),
        }
    })
}

/// Return all pure builtins, that is all builtins that do not rely on
/// I/O outside of the VM and which can be used in any contexts (e.g.
/// WASM).
fn pure_builtins() -> Vec<Builtin> {
    vec![
        Builtin::new("add", 2, |mut args, _| {
            let b = args.pop().unwrap();
            let a = args.pop().unwrap();
            arithmetic_op!(a, b, +)
        }),
        Builtin::new("abort", 1, |mut args, _| {
            return Err(ErrorKind::Abort(
                args.pop().unwrap().to_str()?.as_str().to_owned(),
            ));
        }),
        Builtin::new("attrNames", 1, |args, vm| {
            force!(vm, &args[0], value, {
                let xs = value.to_attrs()?;
                let mut output = Vec::with_capacity(xs.len());

                for (key, _val) in xs.iter() {
                    output.push(Value::String(key.clone()));
                }

                Ok(Value::List(NixList::construct(output.len(), output)))
            })
        }),
        Builtin::new("attrValues", 1, |args, vm| {
            force!(vm, &args[0], value, {
                let xs = value.to_attrs()?;
                let mut output = Vec::with_capacity(xs.len());

                for (_key, val) in xs.iter() {
                    output.push(val.clone());
                }

                Ok(Value::List(NixList::construct(output.len(), output)))
            })
        }),
        Builtin::new("bitAnd", 2, |args, vm| {
            force!(vm, &args[0], x, {
                force!(vm, &args[1], y, {
                    Ok(Value::Integer(x.as_int()? & y.as_int()?))
                })
            })
        }),
        Builtin::new("bitOr", 2, |args, vm| {
            force!(vm, &args[0], x, {
                force!(vm, &args[1], y, {
                    Ok(Value::Integer(x.as_int()? | y.as_int()?))
                })
            })
        }),
        Builtin::new("bitXor", 2, |args, vm| {
            force!(vm, &args[0], x, {
                force!(vm, &args[1], y, {
                    Ok(Value::Integer(x.as_int()? ^ y.as_int()?))
                })
            })
        }),
        Builtin::new("catAttrs", 2, |mut args, _| {
            let list = args.pop().unwrap().to_list()?;
            let key = args.pop().unwrap().to_str()?;
            let mut output = vec![];

            for set in list.into_iter() {
                if let Some(value) = set.to_attrs()?.select(key.as_str()) {
                    output.push(value.clone());
                }
            }

            Ok(Value::List(NixList::construct(output.len(), output)))
        }),
        Builtin::new("compareVersions", 2, |mut args, vm| {
            if let Value::Thunk(t) = &args[0] {
                t.force(vm)?;
            }
            if let Value::Thunk(t) = &args[1] {
                t.force(vm)?;
            }

            let s1 = args.pop().unwrap().to_str()?;
            let s1 = VersionPartsIter::new(s1.as_str());
            let s2 = args.pop().unwrap().to_str()?;
            let s2 = VersionPartsIter::new(s2.as_str());

            match s1.cmp(s2) {
                std::cmp::Ordering::Less => Ok(Value::Integer(1)),
                std::cmp::Ordering::Equal => Ok(Value::Integer(0)),
                std::cmp::Ordering::Greater => Ok(Value::Integer(-1)),
            }
        }),
        Builtin::new("div", 2, |mut args, _| {
            let b = args.pop().unwrap();
            let a = args.pop().unwrap();
            arithmetic_op!(a, b, /)
        }),
        Builtin::new("elemAt", 2, |args, vm| {
            force!(vm, &args[0], value, {
                let xs = value.to_list()?;
                let i = args[1].as_int()?;
                if i < 0 {
                    Err(ErrorKind::IndexOutOfBounds { index: i })
                } else {
                    match xs.get(i as usize) {
                        Some(x) => Ok(x.clone()),
                        None => Err(ErrorKind::IndexOutOfBounds { index: i }),
                    }
                }
            })
        }),
        Builtin::new("length", 1, |args, vm| {
            if let Value::Thunk(t) = &args[0] {
                t.force(vm)?;
            }
            Ok(Value::Integer(args[0].to_list()?.len() as i64))
        }),
        Builtin::new("head", 1, |args, vm| {
            force!(vm, &args[0], xs, {
                match xs.to_list()?.get(0) {
                    Some(x) => Ok(x.clone()),
                    None => Err(ErrorKind::IndexOutOfBounds { index: 0 }),
                }
            })
        }),
        Builtin::new("isAttrs", 1, |args, _| {
            Ok(Value::Bool(matches!(args[0], Value::Attrs(_))))
        }),
        Builtin::new("isBool", 1, |args, _| {
            Ok(Value::Bool(matches!(args[0], Value::Bool(_))))
        }),
        Builtin::new("isFloat", 1, |args, _| {
            Ok(Value::Bool(matches!(args[0], Value::Float(_))))
        }),
        Builtin::new("isFunction", 1, |args, _| {
            Ok(Value::Bool(matches!(
                args[0],
                Value::Closure(_) | Value::Builtin(_)
            )))
        }),
        Builtin::new("isInt", 1, |args, _| {
            Ok(Value::Bool(matches!(args[0], Value::Integer(_))))
        }),
        Builtin::new("isList", 1, |args, _| {
            Ok(Value::Bool(matches!(args[0], Value::List(_))))
        }),
        Builtin::new("isNull", 1, |args, _| {
            Ok(Value::Bool(matches!(args[0], Value::Null)))
        }),
        Builtin::new("isPath", 1, |args, _| {
            Ok(Value::Bool(matches!(args[0], Value::Path(_))))
        }),
        Builtin::new("isString", 1, |args, _| {
            Ok(Value::Bool(matches!(args[0], Value::String(_))))
        }),
        Builtin::new("mul", 2, |mut args, _| {
            let b = args.pop().unwrap();
            let a = args.pop().unwrap();
            arithmetic_op!(a, b, *)
        }),
        Builtin::new("sub", 2, |mut args, _| {
            let b = args.pop().unwrap();
            let a = args.pop().unwrap();
            arithmetic_op!(a, b, -)
        }),
        Builtin::new("throw", 1, |mut args, _| {
            return Err(ErrorKind::Throw(
                args.pop().unwrap().to_str()?.as_str().to_owned(),
            ));
        }),
        Builtin::new("toString", 1, |args, vm| {
            args[0]
                .coerce_to_string(CoercionKind::Strong, vm)
                .map(Value::String)
        }),
        Builtin::new("typeOf", 1, |args, vm| {
            force!(vm, &args[0], value, {
                Ok(Value::String(value.type_of().into()))
            })
        }),
    ]
}

fn builtins_set() -> NixAttrs {
    let mut map: BTreeMap<NixString, Value> = BTreeMap::new();

    for builtin in pure_builtins() {
        map.insert(builtin.name().into(), Value::Builtin(builtin));
    }

    NixAttrs::from_map(map)
}

/// Set of Nix builtins that are globally available.
pub fn global_builtins() -> HashMap<&'static str, Value> {
    let builtins = builtins_set();
    let mut globals: HashMap<&'static str, Value> = HashMap::new();

    // known global builtins from the builtins set.
    for global in &[
        "abort",
        "baseNameOf",
        "derivation",
        "derivationStrict",
        "dirOf",
        "fetchGit",
        "fetchMercurial",
        "fetchTarball",
        "fromTOML",
        "import",
        "isNull",
        "map",
        "placeholder",
        "removeAttrs",
        "scopedImport",
        "throw",
        "toString",
    ] {
        if let Some(builtin) = builtins.select(global) {
            globals.insert(global, builtin.clone());
        }
    }

    globals.insert("builtins", Value::Attrs(Rc::new(builtins)));

    globals
}