//! 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::{self, Ordering};
use std::collections::{BTreeMap, HashSet};
use std::path::PathBuf;
use builtin_macros::builtins;
use regex::Regex;
use crate::arithmetic_op;
use crate::value::BuiltinArgument;
use crate::warnings::WarningKind;
use crate::{
errors::{ErrorKind, EvalResult},
value::{Builtin, CoercionKind, NixAttrs, NixList, NixString, Value},
vm::VM,
};
use self::versions::{VersionPart, VersionPartsIter};
mod versions;
#[cfg(feature = "impure")]
mod impure;
#[cfg(feature = "impure")]
pub use impure::impure_builtins;
// we set TVIX_CURRENT_SYSTEM in build.rs
pub const CURRENT_PLATFORM: &str = env!("TVIX_CURRENT_SYSTEM");
/// Coerce a Nix Value to a plain path, e.g. in order to access the
/// file it points to via either `builtins.toPath` or an impure
/// builtin. This coercion can _never_ be performed in a Nix program
/// without using builtins (i.e. the trick `path: /. + path` to
/// convert from a string to a path wouldn't hit this code).
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))
}
}),
}
}
#[builtins]
mod pure_builtins {
use std::collections::VecDeque;
use super::*;
#[builtin("abort")]
fn builtin_abort(_vm: &mut VM, message: Value) -> Result<Value, ErrorKind> {
Err(ErrorKind::Abort(message.to_str()?.to_string()))
}
#[builtin("add")]
fn builtin_add(vm: &mut VM, #[lazy] x: Value, #[lazy] y: Value) -> Result<Value, ErrorKind> {
arithmetic_op!(&*x.force(vm)?, &*y.force(vm)?, +)
}
#[builtin("all")]
fn builtin_all(vm: &mut VM, pred: Value, list: Value) -> Result<Value, ErrorKind> {
for value in list.to_list()?.into_iter() {
let pred_result = vm.call_with(&pred, [value])?;
if !pred_result.force(vm)?.as_bool()? {
return Ok(Value::Bool(false));
}
}
Ok(Value::Bool(true))
}
#[builtin("any")]
fn builtin_any(vm: &mut VM, pred: Value, list: Value) -> Result<Value, ErrorKind> {
for value in list.to_list()?.into_iter() {
let pred_result = vm.call_with(&pred, [value])?;
if pred_result.force(vm)?.as_bool()? {
return Ok(Value::Bool(true));
}
}
Ok(Value::Bool(false))
}
#[builtin("attrNames")]
fn builtin_attr_names(_: &mut VM, set: Value) -> Result<Value, ErrorKind> {
let xs = set.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("attrValues")]
fn builtin_attr_values(_: &mut VM, set: Value) -> Result<Value, ErrorKind> {
let xs = set.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("baseNameOf")]
fn builtin_base_name_of(vm: &mut VM, s: Value) -> Result<Value, ErrorKind> {
let s = s.coerce_to_string(CoercionKind::Weak, vm)?;
let result: String = s.rsplit_once('/').map(|(_, x)| x).unwrap_or(&s).into();
Ok(result.into())
}
#[builtin("bitAnd")]
fn builtin_bit_and(_: &mut VM, x: Value, y: Value) -> Result<Value, ErrorKind> {
Ok(Value::Integer(x.as_int()? & y.as_int()?))
}
#[builtin("bitOr")]
fn builtin_bit_or(_: &mut VM, x: Value, y: Value) -> Result<Value, ErrorKind> {
Ok(Value::Integer(x.as_int()? | y.as_int()?))
}
#[builtin("bitXor")]
fn builtin_bit_xor(_: &mut VM, x: Value, y: Value) -> Result<Value, ErrorKind> {
Ok(Value::Integer(x.as_int()? ^ y.as_int()?))
}
#[builtin("catAttrs")]
fn builtin_cat_attrs(vm: &mut VM, key: Value, list: Value) -> Result<Value, ErrorKind> {
let key = key.to_str()?;
let list = list.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("ceil")]
fn builtin_ceil(_: &mut VM, double: Value) -> Result<Value, ErrorKind> {
Ok(Value::Integer(double.as_float()?.ceil() as i64))
}
#[builtin("compareVersions")]
fn builtin_compare_versions(_: &mut VM, x: Value, y: Value) -> Result<Value, ErrorKind> {
let s1 = x.to_str()?;
let s1 = VersionPartsIter::new_for_cmp(s1.as_str());
let s2 = y.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("concatLists")]
fn builtin_concat_lists(vm: &mut VM, lists: Value) -> Result<Value, ErrorKind> {
let list = lists.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::<imbl::Vector<Value>>(),
)))
}
#[builtin("concatMap")]
fn builtin_concat_map(vm: &mut VM, f: Value, list: Value) -> Result<Value, ErrorKind> {
let list = list.to_list()?;
let mut res = imbl::Vector::new();
for val in list {
res.extend(vm.call_with(&f, [val])?.force(vm)?.to_list()?);
}
Ok(Value::List(res.into()))
}
#[builtin("concatStringsSep")]
fn builtin_concat_strings_sep(
vm: &mut VM,
separator: Value,
list: Value,
) -> Result<Value, ErrorKind> {
let separator = separator.to_str()?;
let list = list.to_list()?;
let mut res = String::new();
for (i, val) in list.into_iter().enumerate() {
if i != 0 {
res.push_str(&separator);
}
res.push_str(&val.force(vm)?.coerce_to_string(CoercionKind::Weak, vm)?);
}
Ok(res.into())
}
#[builtin("deepSeq")]
fn builtin_deep_seq(vm: &mut VM, x: Value, y: Value) -> Result<Value, ErrorKind> {
x.deep_force(vm, &mut Default::default())?;
Ok(y)
}
#[builtin("div")]
fn builtin_div(vm: &mut VM, #[lazy] x: Value, #[lazy] y: Value) -> Result<Value, ErrorKind> {
arithmetic_op!(&*x.force(vm)?, &*y.force(vm)?, /)
}
#[builtin("dirOf")]
fn builtin_dir_of(vm: &mut VM, s: Value) -> Result<Value, ErrorKind> {
let str = s.coerce_to_string(CoercionKind::Weak, vm)?;
let result = str
.rsplit_once('/')
.map(|(x, _)| match x {
"" => "/",
_ => x,
})
.unwrap_or(".");
if s.is_path() {
Ok(Value::Path(result.into()))
} else {
Ok(result.into())
}
}
#[builtin("elem")]
fn builtin_elem(vm: &mut VM, x: Value, xs: Value) -> Result<Value, ErrorKind> {
for val in xs.to_list()? {
if vm.nix_eq(val, x.clone(), true)? {
return Ok(true.into());
}
}
Ok(false.into())
}
#[builtin("elemAt")]
fn builtin_elem_at(_: &mut VM, xs: Value, i: Value) -> Result<Value, ErrorKind> {
let xs = xs.to_list()?;
let i = i.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("filter")]
fn builtin_filter(vm: &mut VM, pred: Value, list: Value) -> Result<Value, ErrorKind> {
let list: NixList = list.to_list()?;
list.into_iter()
.filter_map(|elem| {
let result = match vm.call_with(&pred, [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<imbl::Vector<Value>, _>>()
.map(|list| Value::List(NixList::from(list)))
.map_err(Into::into)
}
#[builtin("floor")]
fn builtin_floor(_: &mut VM, double: Value) -> Result<Value, ErrorKind> {
Ok(Value::Integer(double.as_float()?.floor() as i64))
}
#[builtin("foldl'")]
fn builtin_foldl(
vm: &mut VM,
op: Value,
#[lazy] mut nul: Value,
list: Value,
) -> Result<Value, ErrorKind> {
let list = list.to_list()?;
for val in list {
nul = vm.call_with(&op, [nul, val])?;
nul.force(vm)?;
}
Ok(nul)
}
#[builtin("functionArgs")]
fn builtin_function_args(_: &mut VM, f: Value) -> Result<Value, ErrorKind> {
let lambda = &f.as_closure()?.lambda();
let formals = if let Some(formals) = &lambda.formals {
formals
} else {
return Ok(Value::attrs(NixAttrs::empty()));
};
Ok(Value::attrs(NixAttrs::from_iter(
formals.arguments.iter().map(|(k, v)| (k.clone(), (*v))),
)))
}
#[builtin("fromJSON")]
fn builtin_from_json(_: &mut VM, json: Value) -> Result<Value, ErrorKind> {
let json_str = json.to_str()?;
let json: serde_json::Value = serde_json::from_str(&json_str)?;
json.try_into()
}
#[builtin("genericClosure")]
fn builtin_generic_closure(vm: &mut VM, input: Value) -> Result<Value, ErrorKind> {
let attrs = input.to_attrs()?;
// The work set is maintained as a VecDeque because new items
// are popped from the front.
let mut work_set: VecDeque<Value> = attrs
.select_required("startSet")?
.force(vm)?
.to_list()?
.into_iter()
.collect();
let operator = attrs.select_required("operator")?;
let mut res = imbl::Vector::new();
let mut done_keys: Vec<Value> = vec![];
let mut insert_key = |k: Value, vm: &mut VM| -> Result<bool, ErrorKind> {
for existing in &done_keys {
if existing.nix_eq(&k, vm)? {
return Ok(false);
}
}
done_keys.push(k);
Ok(true)
};
while let Some(val) = work_set.pop_front() {
let attrs = val.force(vm)?.to_attrs()?;
let key = attrs.select_required("key")?;
if !insert_key(key.clone(), vm)? {
continue;
}
res.push_back(val.clone());
let op_result = vm.call_with(operator, Some(val))?.force(vm)?.to_list()?;
work_set.extend(op_result.into_iter());
}
Ok(Value::List(NixList::from(res)))
}
#[builtin("genList")]
fn builtin_gen_list(vm: &mut VM, generator: Value, length: Value) -> Result<Value, ErrorKind> {
let len = length.as_int()?;
(0..len)
.map(|i| vm.call_with(&generator, [i.into()]))
.collect::<Result<imbl::Vector<Value>, _>>()
.map(|list| Value::List(NixList::from(list)))
.map_err(Into::into)
}
#[builtin("getAttr")]
fn builtin_get_attr(_: &mut VM, key: Value, set: Value) -> Result<Value, ErrorKind> {
let k = key.to_str()?;
let xs = set.to_attrs()?;
match xs.select(k.as_str()) {
Some(x) => Ok(x.clone()),
None => Err(ErrorKind::AttributeNotFound {
name: k.to_string(),
}),
}
}
#[builtin("groupBy")]
fn builtin_group_by(vm: &mut VM, f: Value, list: Value) -> Result<Value, ErrorKind> {
let mut res: BTreeMap<NixString, imbl::Vector<Value>> = BTreeMap::new();
for val in list.to_list()? {
let key = vm.call_with(&f, [val.clone()])?.force(vm)?.to_str()?;
res.entry(key)
.or_insert_with(imbl::Vector::new)
.push_back(val);
}
Ok(Value::attrs(NixAttrs::from_iter(
res.into_iter()
.map(|(k, v)| (k, Value::List(NixList::from(v)))),
)))
}
#[builtin("hasAttr")]
fn builtin_has_attr(_: &mut VM, key: Value, set: Value) -> Result<Value, ErrorKind> {
let k = key.to_str()?;
let xs = set.to_attrs()?;
Ok(Value::Bool(xs.contains(k.as_str())))
}
#[builtin("head")]
fn builtin_head(_: &mut VM, list: Value) -> Result<Value, ErrorKind> {
match list.to_list()?.get(0) {
Some(x) => Ok(x.clone()),
None => Err(ErrorKind::IndexOutOfBounds { index: 0 }),
}
}
#[builtin("intersectAttrs")]
fn builtin_intersect_attrs(_: &mut VM, x: Value, y: Value) -> Result<Value, ErrorKind> {
let attrs1 = x.to_attrs()?;
let attrs2 = y.to_attrs()?;
let res = attrs2.iter().filter_map(|(k, v)| {
if attrs1.contains(k) {
Some((k.clone(), v.clone()))
} else {
None
}
});
Ok(Value::attrs(NixAttrs::from_iter(res)))
}
// For `is*` predicates we force manually, as Value::force also unwraps any Thunks
#[builtin("isAttrs")]
fn builtin_is_attrs(vm: &mut VM, #[lazy] x: Value) -> Result<Value, ErrorKind> {
let value = x.force(vm)?;
Ok(Value::Bool(matches!(*value, Value::Attrs(_))))
}
#[builtin("isBool")]
fn builtin_is_bool(vm: &mut VM, #[lazy] x: Value) -> Result<Value, ErrorKind> {
let value = x.force(vm)?;
Ok(Value::Bool(matches!(*value, Value::Bool(_))))
}
#[builtin("isFloat")]
fn builtin_is_float(vm: &mut VM, #[lazy] x: Value) -> Result<Value, ErrorKind> {
let value = x.force(vm)?;
Ok(Value::Bool(matches!(*value, Value::Float(_))))
}
#[builtin("isFunction")]
fn builtin_is_function(vm: &mut VM, #[lazy] x: Value) -> Result<Value, ErrorKind> {
let value = x.force(vm)?;
Ok(Value::Bool(matches!(
*value,
Value::Closure(_) | Value::Builtin(_)
)))
}
#[builtin("isInt")]
fn builtin_is_int(vm: &mut VM, #[lazy] x: Value) -> Result<Value, ErrorKind> {
let value = x.force(vm)?;
Ok(Value::Bool(matches!(*value, Value::Integer(_))))
}
#[builtin("isList")]
fn builtin_is_list(vm: &mut VM, #[lazy] x: Value) -> Result<Value, ErrorKind> {
let value = x.force(vm)?;
Ok(Value::Bool(matches!(*value, Value::List(_))))
}
#[builtin("isNull")]
fn builtin_is_null(vm: &mut VM, #[lazy] x: Value) -> Result<Value, ErrorKind> {
let value = x.force(vm)?;
Ok(Value::Bool(matches!(*value, Value::Null)))
}
#[builtin("isPath")]
fn builtin_is_path(vm: &mut VM, #[lazy] x: Value) -> Result<Value, ErrorKind> {
let value = x.force(vm)?;
Ok(Value::Bool(matches!(*value, Value::Path(_))))
}
#[builtin("isString")]
fn builtin_is_string(vm: &mut VM, #[lazy] x: Value) -> Result<Value, ErrorKind> {
let value = x.force(vm)?;
Ok(Value::Bool(matches!(*value, Value::String(_))))
}
#[builtin("length")]
fn builtin_length(_: &mut VM, list: Value) -> Result<Value, ErrorKind> {
Ok(Value::Integer(list.to_list()?.len() as i64))
}
#[builtin("lessThan")]
fn builtin_less_than(
vm: &mut VM,
#[lazy] x: Value,
#[lazy] y: Value,
) -> Result<Value, ErrorKind> {
Ok(Value::Bool(matches!(
x.force(vm)?.nix_cmp(&*y.force(vm)?, vm)?,
Some(Ordering::Less)
)))
}
#[builtin("listToAttrs")]
fn builtin_list_to_attrs(vm: &mut VM, list: Value) -> Result<Value, ErrorKind> {
let list = list.to_list()?;
let mut map = BTreeMap::new();
for val in list {
let attrs = val.force(vm)?.to_attrs()?;
let name = attrs.select_required("name")?.force(vm)?.to_str()?;
let value = attrs.select_required("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_iter(map.into_iter())))
}
#[builtin("map")]
fn builtin_map(vm: &mut VM, f: Value, list: Value) -> Result<Value, ErrorKind> {
let list: NixList = list.to_list()?;
list.into_iter()
.map(|val| vm.call_with(&f, [val]))
.collect::<Result<imbl::Vector<Value>, _>>()
.map(|list| Value::List(NixList::from(list)))
.map_err(Into::into)
}
#[builtin("mapAttrs")]
fn builtin_map_attrs(vm: &mut VM, f: Value, attrs: Value) -> Result<Value, ErrorKind> {
let attrs = attrs.to_attrs()?;
let res =
attrs
.as_ref()
.into_iter()
.flat_map(|(key, value)| -> EvalResult<(NixString, Value)> {
let value = vm.call_with(&f, [key.clone().into(), value.clone()])?;
Ok((key.to_owned(), value))
});
Ok(Value::attrs(NixAttrs::from_iter(res)))
}
#[builtin("match")]
fn builtin_match(_: &mut VM, regex: Value, str: Value) -> Result<Value, ErrorKind> {
let s = str.to_str()?;
let re = regex.to_str()?;
let re: Regex = Regex::new(&format!("^{}$", re.as_str())).unwrap();
match re.captures(&s) {
Some(caps) => Ok(caps
.iter()
.skip(1)
.map(|grp| grp.map(|g| Value::from(g.as_str())).unwrap_or(Value::Null))
.collect::<Vec<Value>>()
.into()),
None => Ok(Value::Null),
}
}
#[builtin("mul")]
fn builtin_mul(vm: &mut VM, #[lazy] x: Value, #[lazy] y: Value) -> Result<Value, ErrorKind> {
arithmetic_op!(&*x.force(vm)?, &*y.force(vm)?, *)
}
#[builtin("parseDrvName")]
fn builtin_parse_drv_name(_vm: &mut VM, s: Value) -> Result<Value, ErrorKind> {
// This replicates cppnix's (mis?)handling of codepoints
// above U+007f following 0x2d ('-')
let s = s.to_str()?;
let slice: &[u8] = s.as_str().as_ref();
let (name, dash_and_version) = slice.split_at(
slice
.windows(2)
.enumerate()
.find_map(|x| match x {
(idx, [b'-', c1]) if !c1.is_ascii_alphabetic() => Some(idx),
_ => None,
})
.unwrap_or(slice.len()),
);
let version = dash_and_version
.split_first()
.map(|x| core::str::from_utf8(x.1))
.unwrap_or(Ok(""))?;
Ok(Value::attrs(NixAttrs::from_iter(
[("name", core::str::from_utf8(name)?), ("version", version)].into_iter(),
)))
}
#[builtin("partition")]
fn builtin_partition(vm: &mut VM, pred: Value, list: Value) -> Result<Value, ErrorKind> {
let mut right: Vec<Value> = vec![];
let mut wrong: Vec<Value> = vec![];
let list: NixList = list.to_list()?;
for elem in list {
let result = vm.call_with(&pred, [elem.clone()])?;
if result.force(vm)?.as_bool()? {
right.push(elem);
} else {
wrong.push(elem);
};
}
let res = [("right", right), ("wrong", wrong)];
Ok(Value::attrs(NixAttrs::from_iter(res.into_iter())))
}
#[builtin("removeAttrs")]
fn builtin_remove_attrs(_: &mut VM, attrs: Value, keys: Value) -> Result<Value, ErrorKind> {
let attrs = attrs.to_attrs()?;
let keys = keys
.to_list()?
.into_iter()
.map(|v| v.to_str())
.collect::<Result<HashSet<_>, _>>()?;
let res = attrs.iter().filter_map(|(k, v)| {
if !keys.contains(k) {
Some((k.clone(), v.clone()))
} else {
None
}
});
Ok(Value::attrs(NixAttrs::from_iter(res)))
}
#[builtin("replaceStrings")]
fn builtin_replace_strings(
vm: &mut VM,
from: Value,
to: Value,
s: Value,
) -> Result<Value, ErrorKind> {
let from = from.to_list()?;
from.force_elements(vm)?;
let to = to.to_list()?;
to.force_elements(vm)?;
let string = s.to_str()?;
let mut res = String::new();
let mut i: usize = 0;
let mut empty_string_replace = false;
// This can't be implemented using Rust's string.replace() as
// well as a map because we need to handle errors with results
// as well as "reset" the iterator to zero for the replacement
// everytime there's a successful match.
// Also, Rust's string.replace allocates a new string
// on every call which is not preferable.
'outer: while i < string.len() {
// Try a match in all the from strings
for elem in std::iter::zip(from.iter(), to.iter()) {
let from = elem.0.to_str()?;
let to = elem.1.to_str()?;
if i + from.len() >= string.len() {
continue;
}
// We already applied a from->to with an empty from
// transformation.
// Let's skip it so that we don't loop infinitely
if empty_string_replace && from.as_str().is_empty() {
continue;
}
// if we match the `from` string, let's replace
if &string[i..i + from.len()] == from.as_str() {
res += &to;
i += from.len();
// remember if we applied the empty from->to
empty_string_replace = from.as_str().is_empty();
continue 'outer;
}
}
// If we don't match any `from`, we simply add a character
res += &string[i..i + 1];
i += 1;
// Since we didn't apply anything transformation,
// we reset the empty string replacement
empty_string_replace = false;
}
// Special case when the string is empty or at the string's end
// and one of the from is also empty
for elem in std::iter::zip(from.iter(), to.iter()) {
let from = elem.0.to_str()?;
let to = elem.1.to_str()?;
if from.as_str().is_empty() {
res += &to;
break;
}
}
Ok(Value::String(res.into()))
}
#[builtin("seq")]
fn builtin_seq(_: &mut VM, _x: Value, y: Value) -> Result<Value, ErrorKind> {
// The builtin calling infra has already forced both args for us, so
// we just return the second and ignore the first
Ok(y)
}
#[builtin("split")]
fn builtin_split(_: &mut VM, regex: Value, str: Value) -> Result<Value, ErrorKind> {
let s = str.to_str()?;
let text = s.as_str();
let re = regex.to_str()?;
let re: Regex = Regex::new(re.as_str()).unwrap();
let mut capture_locations = re.capture_locations();
let num_captures = capture_locations.len();
let mut ret = imbl::Vector::new();
let mut pos = 0;
while let Some(thematch) = re.captures_read_at(&mut capture_locations, text, pos) {
// push the unmatched characters preceding the match
ret.push_back(Value::from(&text[pos..thematch.start()]));
// Push a list with one element for each capture
// group in the regex, containing the characters
// matched by that capture group, or null if no match.
// We skip capture 0; it represents the whole match.
let v: imbl::Vector<Value> = (1..num_captures)
.map(|i| capture_locations.get(i))
.map(|o| {
o.map(|(start, end)| Value::from(&text[start..end]))
.unwrap_or(Value::Null)
})
.collect();
ret.push_back(Value::List(NixList::from(v)));
pos = thematch.end();
}
// push the unmatched characters following the last match
ret.push_back(Value::from(&text[pos..]));
Ok(Value::List(NixList::from(ret)))
}
#[builtin("sort")]
fn builtin_sort(vm: &mut VM, comparator: Value, list: Value) -> Result<Value, ErrorKind> {
// TODO: the bound on the sort function in
// `imbl::Vector::sort_by` is `Fn(...)`, which means that we can
// not use the mutable VM inside of its closure, hence the
// dance via `Vec`. I think this is just an unnecessarily
// restrictive bound in `im`, not a functional requirement.
let mut list = list.to_list()?.into_iter().collect::<Vec<_>>();
// Used to let errors "escape" from the sorting closure. If anything
// ends up setting an error, it is returned from this function.
let mut error: Option<ErrorKind> = None;
list.sort_by(|lhs, rhs| {
let result = vm
.call_with(&comparator, [lhs.clone(), rhs.clone()])
.map_err(|err| ErrorKind::ThunkForce(Box::new(err)))
.and_then(|v| v.force(vm)?.as_bool());
match (&error, result) {
// The contained closure only returns a "less
// than?"-boolean, no way to yield "equal".
(None, Ok(true)) => Ordering::Less,
(None, Ok(false)) => Ordering::Greater,
// Closest thing to short-circuiting out if an error was
// thrown.
(Some(_), _) => Ordering::Equal,
// Propagate the error if one was encountered.
(_, Err(e)) => {
error = Some(e);
Ordering::Equal
}
}
});
match error {
#[allow(deprecated)] // imbl::Vector usage prevented by its API
None => Ok(Value::List(NixList::from_vec(list))),
Some(e) => Err(e),
}
}
#[builtin("splitVersion")]
fn builtin_split_version(_: &mut VM, s: Value) -> Result<Value, ErrorKind> {
let s = s.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("stringLength")]
fn builtin_string_length(vm: &mut VM, #[lazy] s: Value) -> Result<Value, ErrorKind> {
// also forces the value
let s = s.coerce_to_string(CoercionKind::Weak, vm)?;
Ok(Value::Integer(s.as_str().len() as i64))
}
#[builtin("sub")]
fn builtin_sub(vm: &mut VM, #[lazy] x: Value, #[lazy] y: Value) -> Result<Value, ErrorKind> {
arithmetic_op!(&*x.force(vm)?, &*y.force(vm)?, -)
}
#[builtin("substring")]
fn builtin_substring(
_: &mut VM,
start: Value,
len: Value,
s: Value,
) -> Result<Value, ErrorKind> {
let beg = start.as_int()?;
let len = len.as_int()?;
let x = s.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..end].into()))
}
#[builtin("tail")]
fn builtin_tail(_: &mut VM, list: Value) -> Result<Value, ErrorKind> {
let xs = list.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("throw")]
fn builtin_throw(_: &mut VM, message: Value) -> Result<Value, ErrorKind> {
Err(ErrorKind::Throw(message.to_str()?.to_string()))
}
#[builtin("toString")]
fn builtin_to_string(vm: &mut VM, #[lazy] x: Value) -> Result<Value, ErrorKind> {
// coerce_to_string forces for us
x.coerce_to_string(CoercionKind::Strong, vm)
.map(Value::String)
}
#[builtin("placeholder")]
fn builtin_placeholder(vm: &mut VM, #[lazy] _: Value) -> Result<Value, ErrorKind> {
// TODO(amjoseph)
vm.emit_warning(WarningKind::NotImplemented("builtins.placeholder"));
Ok("<builtins.placeholder-is-not-implemented-in-tvix-yet>".into())
}
#[builtin("trace")]
fn builtin_trace(_: &mut VM, message: Value, value: Value) -> Result<Value, ErrorKind> {
// TODO(grfn): `trace` should be pluggable and capturable, probably via a method on
// the VM
println!("trace: {} :: {}", message, message.type_of());
Ok(value)
}
#[builtin("toPath")]
fn builtin_to_path(vm: &mut VM, #[lazy] s: Value) -> Result<Value, ErrorKind> {
let path: Value = crate::value::canon_path(coerce_value_to_path(&s, vm)?).into();
Ok(path.coerce_to_string(CoercionKind::Weak, vm)?.into())
}
#[builtin("tryEval")]
fn builtin_try_eval(vm: &mut VM, #[lazy] e: Value) -> Result<Value, ErrorKind> {
let res = match e.force(vm) {
Ok(value) => [("value", (*value).clone()), ("success", true.into())],
Err(e) if e.is_catchable() => [("value", false.into()), ("success", false.into())],
Err(e) => return Err(e),
};
Ok(Value::attrs(NixAttrs::from_iter(res.into_iter())))
}
#[builtin("typeOf")]
fn builtin_type_of(vm: &mut VM, #[lazy] x: Value) -> Result<Value, ErrorKind> {
// 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 = x.force(vm)?;
Ok(Value::String(value.type_of().into()))
}
}
fn builtin_tuple(builtin: Builtin) -> (&'static str, Value) {
(builtin.name(), Value::Builtin(builtin))
}
/// The set of standard pure builtins in Nix, mostly concerned with
/// data structure manipulation (string, attrs, list, etc. functions).
pub fn pure_builtins() -> Vec<(&'static str, Value)> {
let mut result = pure_builtins::builtins()
.into_iter()
.map(builtin_tuple)
.collect::<Vec<_>>();
// Pure-value builtins
result.push(("nixVersion", Value::String("2.3-compat-tvix-0.1".into())));
result.push(("langVersion", Value::Integer(6)));
result.push((
"currentSystem",
crate::systems::llvm_triple_to_nix_double(CURRENT_PLATFORM).into(),
));
result
}
/// Placeholder builtins that technically have a function which we do
/// not yet implement, but which is also not easily observable from
/// within a pure evaluation context.
///
/// These are used as a crutch to make progress on nixpkgs evaluation.
pub fn placeholders() -> Vec<(&'static str, Value)> {
let ph = vec![
Builtin::new(
"addErrorContext",
&[
BuiltinArgument {
strict: false,
name: "context",
},
BuiltinArgument {
strict: false,
name: "value",
},
],
None,
|mut args: Vec<Value>, vm: &mut VM| {
vm.emit_warning(WarningKind::NotImplemented("builtins.addErrorContext"));
Ok(args.pop().unwrap())
},
),
Builtin::new(
"unsafeDiscardStringContext",
&[BuiltinArgument {
strict: true,
name: "s",
}],
None,
|mut args: Vec<Value>, vm: &mut VM| {
vm.emit_warning(WarningKind::NotImplemented(
"builtins.unsafeDiscardStringContext",
));
Ok(args.pop().unwrap())
},
),
Builtin::new(
"unsafeGetAttrPos",
&[
BuiltinArgument {
strict: true,
name: "name",
},
BuiltinArgument {
strict: true,
name: "attrset",
},
],
None,
|mut args: Vec<Value>, vm: &mut VM| {
vm.emit_warning(WarningKind::NotImplemented("builtins.unsafeGetAttrsPos"));
let _attrset = args.pop().unwrap().to_attrs();
let _name = args.pop().unwrap().to_str();
let res = [
("line", 42.into()),
("col", 42.into()),
("file", Value::Path("/deep/thought".into())),
];
Ok(Value::attrs(NixAttrs::from_iter(res.into_iter())))
},
),
Builtin::new(
"derivation",
&[BuiltinArgument {
strict: true,
name: "attrs",
}],
None,
|args: Vec<Value>, vm: &mut VM| {
vm.emit_warning(WarningKind::NotImplemented("builtins.derivation"));
// We do not implement derivations yet, so this function sets mock
// values on the fields that a real derivation would contain.
//
// Crucially this means we do not yet *validate* the values either.
let input = args[0].to_attrs()?;
let attrs = input.update(NixAttrs::from_iter(
[
(
"outPath",
"/nix/store/00000000000000000000000000000000-mock",
),
(
"drvPath",
"/nix/store/00000000000000000000000000000000-mock.drv",
),
("type", "derivation"),
]
.into_iter(),
));
Ok(Value::Attrs(Box::new(attrs)))
},
),
];
ph.into_iter().map(builtin_tuple).collect()
}
