about summary refs log tree commit diff
path: root/tvix/eval/src/builtins/mod.rs
blob: 5819796236cd0a245f10eedb9283aac6bfaaef08 (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
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
//! 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::cmp;
use std::collections::{BTreeMap, HashMap};
use std::path::PathBuf;

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

use crate::{arithmetic_op, cmp_op};

use self::versions::{VersionPart, VersionPartsIter};

#[cfg(feature = "impure")]
pub mod impure;
pub mod versions;

/// 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.
#[allow(dead_code)] // TODO(sterni): remove this once the function is in use
pub fn coerce_value_to_path(v: &Value, vm: &mut VM) -> Result<PathBuf, ErrorKind> {
    let value = v.force(vm)?;
    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",
            &[false, false],
            |args: Vec<Value>, vm: &mut VM| arithmetic_op!(&*args[0].force(vm)?, &*args[1].force(vm)?, +),
        ),
        Builtin::new("abort", &[true], |args: Vec<Value>, _: &mut VM| {
            Err(ErrorKind::Abort(args[0].to_str()?.to_string()))
        }),
        Builtin::new("all", &[true, true], |args: Vec<Value>, vm: &mut VM| {
            for value in args[1].to_list()?.into_iter() {
                let pred_result = vm.call_with(&args[0], [value])?;

                if !pred_result.force(vm)?.as_bool()? {
                    return Ok(Value::Bool(false));
                }
            }

            Ok(Value::Bool(true))
        }),
        Builtin::new("any", &[true, true], |args: Vec<Value>, vm: &mut VM| {
            for value in args[1].to_list()?.into_iter() {
                let pred_result = vm.call_with(&args[0], [value])?;

                if pred_result.force(vm)?.as_bool()? {
                    return Ok(Value::Bool(true));
                }
            }

            Ok(Value::Bool(false))
        }),
        Builtin::new("attrNames", &[true], |args: Vec<Value>, _: &mut VM| {
            let xs = args[0].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", &[true], |args: Vec<Value>, _: &mut VM| {
            let xs = args[0].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", &[true, true], |args: Vec<Value>, _: &mut VM| {
            Ok(Value::Integer(args[0].as_int()? & args[1].as_int()?))
        }),
        Builtin::new("bitOr", &[true, true], |args: Vec<Value>, _: &mut VM| {
            Ok(Value::Integer(args[0].as_int()? | args[1].as_int()?))
        }),
        Builtin::new("bitXor", &[true, true], |args: Vec<Value>, _: &mut VM| {
            Ok(Value::Integer(args[0].as_int()? ^ args[1].as_int()?))
        }),
        Builtin::new(
            "catAttrs",
            &[true, true],
            |args: Vec<Value>, vm: &mut VM| {
                let key = args[0].to_str()?;
                let list = args[1].to_list()?;
                let mut output = vec![];

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

                Ok(Value::List(NixList::construct(output.len(), output)))
            },
        ),
        Builtin::new(
            "compareVersions",
            &[true, true],
            |args: Vec<Value>, _: &mut VM| {
                let s1 = args[0].to_str()?;
                let s1 = VersionPartsIter::new_for_cmp(s1.as_str());
                let s2 = args[1].to_str()?;
                let s2 = VersionPartsIter::new_for_cmp(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("concatLists", &[true], |args: Vec<Value>, vm: &mut VM| {
            let list = args[0].to_list()?;
            let lists = list
                .into_iter()
                .map(|elem| {
                    let value = elem.force(vm)?;
                    value.to_list()
                })
                .collect::<Result<Vec<NixList>, ErrorKind>>()?;

            Ok(Value::List(NixList::from(
                lists.into_iter().flatten().collect::<Vec<Value>>(),
            )))
        }),
        Builtin::new(
            "concatMap",
            &[true, true],
            |args: Vec<Value>, vm: &mut VM| {
                let list = args[1].to_list()?;
                let mut res = Vec::new();
                for val in list {
                    res.extend(vm.call_with(&args[0], [val])?.force(vm)?.to_list()?);
                }
                Ok(Value::List(res.into()))
            },
        ),
        Builtin::new(
            "div",
            &[false, false],
            |args: Vec<Value>, vm: &mut VM| arithmetic_op!(&*args[0].force(vm)?, &*args[1].force(vm)?, /),
        ),
        Builtin::new("elemAt", &[true, true], |args: Vec<Value>, _: &mut VM| {
            let xs = args[0].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("filter", &[true, true], |args: Vec<Value>, vm: &mut VM| {
            let list: NixList = args[1].to_list()?;

            list.into_iter()
                .filter_map(|elem| {
                    let result = match vm.call_with(&args[0], [elem.clone()]) {
                        Err(err) => return Some(Err(err)),
                        Ok(result) => result,
                    };

                    // Must be assigned to a local to avoid a borrowcheck
                    // failure related to the ForceResult destructor.
                    let result = match result.force(vm) {
                        Err(err) => Some(Err(vm.error(err))),
                        Ok(value) => match value.as_bool() {
                            Ok(true) => Some(Ok(elem)),
                            Ok(false) => None,
                            Err(err) => Some(Err(vm.error(err))),
                        },
                    };

                    result
                })
                .collect::<Result<Vec<Value>, _>>()
                .map(|list| Value::List(NixList::from(list)))
                .map_err(Into::into)
        }),
        Builtin::new(
            "foldl'",
            &[true, false, true],
            |mut args: Vec<Value>, vm: &mut VM| {
                let list = args.pop().unwrap().to_list()?;
                let mut res = args.pop().unwrap();
                let op = args.pop().unwrap();
                for val in list {
                    val.force(vm)?;
                    res = vm.call_with(&op, [val, res])?;
                }

                Ok(res)
            },
        ),
        Builtin::new("genList", &[true, true], |args: Vec<Value>, vm: &mut VM| {
            let len = args[1].as_int()?;
            (0..len)
                .map(|i| vm.call_with(&args[0], [i.into()]))
                .collect::<Result<Vec<Value>, _>>()
                .map(|list| Value::List(NixList::from(list)))
                .map_err(Into::into)
        }),
        Builtin::new("getAttr", &[true, true], |args: Vec<Value>, _: &mut VM| {
            let k = args[0].to_str()?;
            let xs = args[1].to_attrs()?;

            match xs.select(k.as_str()) {
                Some(x) => Ok(x.clone()),
                None => Err(ErrorKind::AttributeNotFound {
                    name: k.to_string(),
                }),
            }
        }),
        Builtin::new("length", &[true], |args: Vec<Value>, _: &mut VM| {
            Ok(Value::Integer(args[0].to_list()?.len() as i64))
        }),
        Builtin::new("map", &[true, true], |args: Vec<Value>, vm: &mut VM| {
            let list: NixList = args[1].to_list()?;

            list.into_iter()
                .map(|val| vm.call_with(&args[0], [val]))
                .collect::<Result<Vec<Value>, _>>()
                .map(|list| Value::List(NixList::from(list)))
                .map_err(Into::into)
        }),
        Builtin::new(
            "lessThan",
            &[false, false],
            |args: Vec<Value>, vm: &mut VM| cmp_op!(&*args[0].force(vm)?, &*args[1].force(vm)?, <),
        ),
        Builtin::new("hasAttr", &[true, true], |args: Vec<Value>, _: &mut VM| {
            let k = args[0].to_str()?;
            let xs = args[1].to_attrs()?;

            Ok(Value::Bool(xs.contains(k.as_str())))
        }),
        Builtin::new("head", &[true], |args: Vec<Value>, _: &mut VM| {
            match args[0].to_list()?.get(0) {
                Some(x) => Ok(x.clone()),
                None => Err(ErrorKind::IndexOutOfBounds { index: 0 }),
            }
        }),
        // For `is*` predicates we force manually, as Value::force also unwraps any Thunks
        Builtin::new("isAttrs", &[false], |args: Vec<Value>, vm: &mut VM| {
            let value = args[0].force(vm)?;
            Ok(Value::Bool(matches!(*value, Value::Attrs(_))))
        }),
        Builtin::new("isBool", &[false], |args: Vec<Value>, vm: &mut VM| {
            let value = args[0].force(vm)?;
            Ok(Value::Bool(matches!(*value, Value::Bool(_))))
        }),
        Builtin::new("isFloat", &[false], |args: Vec<Value>, vm: &mut VM| {
            let value = args[0].force(vm)?;
            Ok(Value::Bool(matches!(*value, Value::Float(_))))
        }),
        Builtin::new("isFunction", &[false], |args: Vec<Value>, vm: &mut VM| {
            let value = args[0].force(vm)?;
            Ok(Value::Bool(matches!(
                *value,
                Value::Closure(_) | Value::Builtin(_)
            )))
        }),
        Builtin::new("isInt", &[false], |args: Vec<Value>, vm: &mut VM| {
            let value = args[0].force(vm)?;
            Ok(Value::Bool(matches!(*value, Value::Integer(_))))
        }),
        Builtin::new("isList", &[false], |args: Vec<Value>, vm: &mut VM| {
            let value = args[0].force(vm)?;
            Ok(Value::Bool(matches!(*value, Value::List(_))))
        }),
        Builtin::new("isNull", &[false], |args: Vec<Value>, vm: &mut VM| {
            let value = args[0].force(vm)?;
            Ok(Value::Bool(matches!(*value, Value::Null)))
        }),
        Builtin::new("isPath", &[false], |args: Vec<Value>, vm: &mut VM| {
            let value = args[0].force(vm)?;
            Ok(Value::Bool(matches!(*value, Value::Path(_))))
        }),
        Builtin::new("isString", &[false], |args: Vec<Value>, vm: &mut VM| {
            let value = args[0].force(vm)?;
            Ok(Value::Bool(matches!(*value, Value::String(_))))
        }),
        Builtin::new("listToAttrs", &[true], |args: Vec<Value>, vm: &mut VM| {
            let list = args[0].to_list()?;
            let mut map = BTreeMap::new();
            for val in list {
                let attrs = val.force(vm)?.to_attrs()?;
                let get = |key| {
                    attrs
                        .select(key)
                        .ok_or(ErrorKind::AttributeNotFound { name: key.into() })
                };
                let name = get("name")?.to_str()?;
                let value = get("value")?.clone();
                // Map entries earlier in the list take precedence over entries later in the list
                map.entry(name).or_insert(value);
            }
            Ok(Value::attrs(NixAttrs::from_map(map)))
        }),
        Builtin::new(
            "mul",
            &[false, false],
            |args: Vec<Value>, vm: &mut VM| arithmetic_op!(&*args[0].force(vm)?, &*args[1].force(vm)?, *),
        ),
        Builtin::new("splitVersion", &[true], |args: Vec<Value>, _: &mut VM| {
            let s = args[0].to_str()?;
            let s = VersionPartsIter::new(s.as_str());

            let parts = s
                .map(|s| {
                    Value::String(match s {
                        VersionPart::Number(n) => n.into(),
                        VersionPart::Word(w) => w.into(),
                    })
                })
                .collect::<Vec<Value>>();
            Ok(Value::List(NixList::construct(parts.len(), parts)))
        }),
        Builtin::new("stringLength", &[false], |args: Vec<Value>, vm: &mut VM| {
            // also forces the value
            let s = args[0].coerce_to_string(CoercionKind::Weak, vm)?;
            Ok(Value::Integer(s.as_str().len() as i64))
        }),
        Builtin::new(
            "sub",
            &[false, false],
            |args: Vec<Value>, vm: &mut VM| arithmetic_op!(&*args[0].force(vm)?, &*args[1].force(vm)?, -),
        ),
        Builtin::new(
            "substring",
            &[true, true, true],
            |args: Vec<Value>, _: &mut VM| {
                let beg = args[0].as_int()?;
                let len = args[1].as_int()?;
                let x = args[2].to_str()?;

                if beg < 0 {
                    return Err(ErrorKind::IndexOutOfBounds { index: beg });
                }
                let beg = beg as usize;

                // Nix doesn't assert that the length argument is
                // non-negative when the starting index is GTE the
                // string's length.
                if beg >= x.as_str().len() {
                    return Ok(Value::String("".into()));
                }

                if len < 0 {
                    return Err(ErrorKind::NegativeLength { length: len });
                }

                let len = len as usize;
                let end = cmp::min(beg + len, x.as_str().len());

                Ok(Value::String(
                    x.as_str()[(beg as usize)..(end as usize)].into(),
                ))
            },
        ),
        Builtin::new("tail", &[true], |args: Vec<Value>, _: &mut VM| {
            let xs = args[0].to_list()?;

            if xs.len() == 0 {
                Err(ErrorKind::TailEmptyList)
            } else {
                let output = xs.into_iter().skip(1).collect::<Vec<_>>();
                Ok(Value::List(NixList::construct(output.len(), output)))
            }
        }),
        Builtin::new("throw", &[true], |args: Vec<Value>, _: &mut VM| {
            Err(ErrorKind::Throw(args[0].to_str()?.to_string()))
        }),
        // coerce_to_string forces for us
        Builtin::new("toString", &[false], |args: Vec<Value>, vm: &mut VM| {
            args[0]
                .coerce_to_string(CoercionKind::Strong, vm)
                .map(Value::String)
        }),
        Builtin::new("typeOf", &[false], |args: Vec<Value>, vm: &mut VM| {
            // We force manually here because it also unwraps the Thunk
            // representation, if any.
            // TODO(sterni): it'd be nice if we didn't have to worry about this
            let value = args[0].force(vm)?;
            Ok(Value::String(value.type_of().into()))
        }),
    ]
}

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

    // Pure-value builtins
    map.insert(
        "nixVersion".into(),
        Value::String("2.3-compat-tvix-0.1".into()),
    );

    let mut add_builtins = |builtins: Vec<Builtin>| {
        for builtin in builtins {
            map.insert(builtin.name().into(), Value::Builtin(builtin));
        }
    };

    add_builtins(pure_builtins());
    #[cfg(feature = "impure")]
    {
        map.extend(impure::builtins());
    }

    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(builtins));

    globals
}