//! 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 builtin_macros::builtins;
use genawaiter::rc::Gen;
use imbl::OrdMap;
use regex::Regex;
use std::cmp::{self, Ordering};
use std::collections::VecDeque;
use std::collections::{BTreeMap, HashSet};
use std::path::PathBuf;
use crate::arithmetic_op;
use crate::value::PointerEquality;
use crate::vm::generators::{self, GenCo};
use crate::warnings::WarningKind;
use crate::{
self as tvix_eval,
errors::{CatchableErrorKind, ErrorKind},
value::{CoercionKind, NixAttrs, NixList, NixString, SharedThunkSet, Thunk, Value},
};
use self::versions::{VersionPart, VersionPartsIter};
mod to_xml;
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 async fn coerce_value_to_path(
co: &GenCo,
v: Value,
) -> Result<Result<PathBuf, CatchableErrorKind>, ErrorKind> {
let value = generators::request_force(co, v).await;
if let Value::Path(p) = value {
return Ok(Ok(*p));
}
match generators::request_string_coerce(co, value, CoercionKind::Weak).await {
Ok(vs) => {
let path = PathBuf::from(vs.as_str());
if path.is_absolute() {
Ok(Ok(path))
} else {
Err(ErrorKind::NotAnAbsolutePath(path))
}
}
Err(cek) => Ok(Err(cek)),
}
}
#[builtins]
mod pure_builtins {
use crate::value::PointerEquality;
use super::*;
#[builtin("abort")]
async fn builtin_abort(co: GenCo, message: Value) -> Result<Value, ErrorKind> {
Err(ErrorKind::Abort(message.to_str()?.to_string()))
}
#[builtin("add")]
async fn builtin_add(co: GenCo, x: Value, y: Value) -> Result<Value, ErrorKind> {
arithmetic_op!(&x, &y, +)
}
#[builtin("all")]
async fn builtin_all(co: GenCo, pred: Value, list: Value) -> Result<Value, ErrorKind> {
for value in list.to_list()?.into_iter() {
let pred_result = generators::request_call_with(&co, pred.clone(), [value]).await;
let pred_result = generators::request_force(&co, pred_result).await;
if !pred_result.as_bool()? {
return Ok(Value::Bool(false));
}
}
Ok(Value::Bool(true))
}
#[builtin("any")]
async fn builtin_any(co: GenCo, pred: Value, list: Value) -> Result<Value, ErrorKind> {
for value in list.to_list()?.into_iter() {
let pred_result = generators::request_call_with(&co, pred.clone(), [value]).await;
let pred_result = generators::request_force(&co, pred_result).await;
if pred_result.as_bool()? {
return Ok(Value::Bool(true));
}
}
Ok(Value::Bool(false))
}
#[builtin("attrNames")]
async fn builtin_attr_names(co: GenCo, 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")]
async fn builtin_attr_values(co: GenCo, 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")]
async fn builtin_base_name_of(co: GenCo, s: Value) -> Result<Value, ErrorKind> {
let s = s.coerce_to_string(co, CoercionKind::Weak).await?.to_str()?;
let result: String = s.rsplit_once('/').map(|(_, x)| x).unwrap_or(&s).into();
Ok(result.into())
}
#[builtin("bitAnd")]
async fn builtin_bit_and(co: GenCo, x: Value, y: Value) -> Result<Value, ErrorKind> {
Ok(Value::Integer(x.as_int()? & y.as_int()?))
}
#[builtin("bitOr")]
async fn builtin_bit_or(co: GenCo, x: Value, y: Value) -> Result<Value, ErrorKind> {
Ok(Value::Integer(x.as_int()? | y.as_int()?))
}
#[builtin("bitXor")]
async fn builtin_bit_xor(co: GenCo, x: Value, y: Value) -> Result<Value, ErrorKind> {
Ok(Value::Integer(x.as_int()? ^ y.as_int()?))
}
#[builtin("catAttrs")]
async fn builtin_cat_attrs(co: GenCo, 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 = generators::request_force(&co, item).await.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")]
async fn builtin_ceil(co: GenCo, double: Value) -> Result<Value, ErrorKind> {
Ok(Value::Integer(double.as_float()?.ceil() as i64))
}
#[builtin("compareVersions")]
async fn builtin_compare_versions(co: GenCo, 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")]
async fn builtin_concat_lists(co: GenCo, lists: Value) -> Result<Value, ErrorKind> {
let mut out = imbl::Vector::new();
for value in lists.to_list()? {
let list = generators::request_force(&co, value).await.to_list()?;
out.extend(list.into_iter());
}
Ok(Value::List(out.into()))
}
#[builtin("concatMap")]
async fn builtin_concat_map(co: GenCo, f: Value, list: Value) -> Result<Value, ErrorKind> {
let list = list.to_list()?;
let mut res = imbl::Vector::new();
for val in list {
let out = generators::request_call_with(&co, f.clone(), [val]).await;
let out = generators::request_force(&co, out).await;
res.extend(out.to_list()?);
}
Ok(Value::List(res.into()))
}
#[builtin("concatStringsSep")]
async fn builtin_concat_strings_sep(
co: GenCo,
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);
}
match generators::request_string_coerce(&co, val, CoercionKind::Weak).await {
Ok(s) => res.push_str(s.as_str()),
Err(c) => return Ok(Value::Catchable(c)),
}
}
Ok(res.into())
}
#[builtin("deepSeq")]
async fn builtin_deep_seq(co: GenCo, x: Value, y: Value) -> Result<Value, ErrorKind> {
generators::request_deep_force(&co, x, SharedThunkSet::default()).await;
Ok(y)
}
#[builtin("div")]
async fn builtin_div(co: GenCo, x: Value, y: Value) -> Result<Value, ErrorKind> {
arithmetic_op!(&x, &y, /)
}
#[builtin("dirOf")]
async fn builtin_dir_of(co: GenCo, s: Value) -> Result<Value, ErrorKind> {
let is_path = s.is_path();
let str = s.coerce_to_string(co, CoercionKind::Weak).await?.to_str()?;
let result = str
.rsplit_once('/')
.map(|(x, _)| match x {
"" => "/",
_ => x,
})
.unwrap_or(".");
if is_path {
Ok(Value::Path(Box::new(result.into())))
} else {
Ok(result.into())
}
}
#[builtin("elem")]
async fn builtin_elem(co: GenCo, x: Value, xs: Value) -> Result<Value, ErrorKind> {
for val in xs.to_list()? {
if generators::check_equality(&co, x.clone(), val, PointerEquality::AllowAll).await? {
return Ok(true.into());
}
}
Ok(false.into())
}
#[builtin("elemAt")]
async fn builtin_elem_at(co: GenCo, 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")]
async fn builtin_filter(co: GenCo, pred: Value, list: Value) -> Result<Value, ErrorKind> {
let list: NixList = list.to_list()?;
let mut out = imbl::Vector::new();
for value in list {
let result = generators::request_call_with(&co, pred.clone(), [value.clone()]).await;
if generators::request_force(&co, result).await.as_bool()? {
out.push_back(value);
}
}
Ok(Value::List(out.into()))
}
#[builtin("floor")]
async fn builtin_floor(co: GenCo, double: Value) -> Result<Value, ErrorKind> {
Ok(Value::Integer(double.as_float()?.floor() as i64))
}
#[builtin("foldl'")]
async fn builtin_foldl(
co: GenCo,
op: Value,
#[lazy] nul: Value,
list: Value,
) -> Result<Value, ErrorKind> {
let mut nul = nul;
let list = list.to_list()?;
for val in list {
// Every call of `op` is forced immediately, but `nul` is not, see
// https://github.com/NixOS/nix/blob/940e9eb8/src/libexpr/primops.cc#L3069-L3070C36
// and our tests for foldl'.
nul = generators::request_call_with(&co, op.clone(), [nul, val]).await;
nul = generators::request_force(&co, nul).await;
if let c @ Value::Catchable(_) = nul {
return Ok(c);
}
}
Ok(nul)
}
#[builtin("functionArgs")]
async fn builtin_function_args(co: GenCo, 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")]
async fn builtin_from_json(co: GenCo, json: Value) -> Result<Value, ErrorKind> {
let json_str = json.to_str()?;
serde_json::from_str(&json_str).map_err(|err| err.into())
}
#[builtin("toJSON")]
async fn builtin_to_json(co: GenCo, val: Value) -> Result<Value, ErrorKind> {
match val.into_json(&co).await? {
Err(cek) => Ok(Value::Catchable(cek)),
Ok(json_value) => {
let json_str = serde_json::to_string(&json_value)?;
Ok(json_str.into())
}
}
}
#[builtin("fromTOML")]
async fn builtin_from_toml(co: GenCo, toml: Value) -> Result<Value, ErrorKind> {
let toml_str = toml.to_str()?;
toml::from_str(&toml_str).map_err(|err| err.into())
}
#[builtin("genericClosure")]
async fn builtin_generic_closure(co: GenCo, 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> =
generators::request_force(&co, attrs.select_required("startSet")?.clone())
.await
.to_list()?
.into_iter()
.collect();
let operator = attrs.select_required("operator")?;
let mut res = imbl::Vector::new();
let mut done_keys: Vec<Value> = vec![];
while let Some(val) = work_set.pop_front() {
let val = generators::request_force(&co, val).await;
let attrs = val.to_attrs()?;
let key = attrs.select_required("key")?;
if !bgc_insert_key(&co, key.clone(), &mut done_keys).await? {
continue;
}
res.push_back(val.clone());
let op_result = generators::request_force(
&co,
generators::request_call_with(&co, operator.clone(), [val]).await,
)
.await;
work_set.extend(op_result.to_list()?.into_iter());
}
Ok(Value::List(NixList::from(res)))
}
#[builtin("genList")]
async fn builtin_gen_list(
co: GenCo,
generator: Value,
length: Value,
) -> Result<Value, ErrorKind> {
let mut out = imbl::Vector::<Value>::new();
let len = length.as_int()?;
// the best span we can getโฆ
let span = generators::request_span(&co).await;
for i in 0..len {
let val = Value::Thunk(Thunk::new_suspended_call(
generator.clone(),
i.into(),
span.clone(),
));
out.push_back(val);
}
Ok(Value::List(out.into()))
}
#[builtin("getAttr")]
async fn builtin_get_attr(co: GenCo, 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")]
async fn builtin_group_by(co: GenCo, 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 = generators::request_force(
&co,
generators::request_call_with(&co, f.clone(), [val.clone()]).await,
)
.await
.to_str()?;
res.entry(key).or_default().push_back(val);
}
Ok(Value::attrs(NixAttrs::from_iter(
res.into_iter()
.map(|(k, v)| (k, Value::List(NixList::from(v)))),
)))
}
#[builtin("hasAttr")]
async fn builtin_has_attr(co: GenCo, 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")]
async fn builtin_head(co: GenCo, list: Value) -> Result<Value, ErrorKind> {
match list.to_list()?.get(0) {
Some(x) => Ok(x.clone()),
None => Err(ErrorKind::IndexOutOfBounds { index: 0 }),
}
}
#[builtin("intersectAttrs")]
async fn builtin_intersect_attrs(co: GenCo, x: Value, y: Value) -> Result<Value, ErrorKind> {
let left_set = x.to_attrs()?;
if left_set.is_empty() {
return Ok(Value::attrs(NixAttrs::empty()));
}
let mut left_keys = left_set.keys();
let right_set = y.to_attrs()?;
if right_set.is_empty() {
return Ok(Value::attrs(NixAttrs::empty()));
}
let mut right_keys = right_set.keys();
let mut out: OrdMap<NixString, Value> = OrdMap::new();
// Both iterators have at least one entry
let mut left = left_keys.next().unwrap();
let mut right = right_keys.next().unwrap();
// Calculate the intersection of the attribute sets by simultaneously
// advancing two key iterators, and inserting into the result set from
// the right side when the keys match. Iteration over Nix attribute sets
// is in sorted lexicographical order, so we can advance either iterator
// until it "catches up" with its counterpart.
//
// Only when keys match are the key and value clones actually allocated.
//
// We opted for this implementation over simpler ones because of the
// heavy use of this function in nixpkgs.
loop {
if left == right {
// We know that the key exists in the set, and can
// skip the check instructions.
unsafe {
out.insert(
right.clone(),
right_set.select(right).unwrap_unchecked().clone(),
);
}
left = match left_keys.next() {
Some(x) => x,
None => break,
};
right = match right_keys.next() {
Some(x) => x,
None => break,
};
continue;
}
if left < right {
left = match left_keys.next() {
Some(x) => x,
None => break,
};
continue;
}
if right < left {
right = match right_keys.next() {
Some(x) => x,
None => break,
};
continue;
}
}
Ok(Value::attrs(out.into()))
}
#[builtin("isAttrs")]
async fn builtin_is_attrs(co: GenCo, value: Value) -> Result<Value, ErrorKind> {
Ok(Value::Bool(matches!(value, Value::Attrs(_))))
}
#[builtin("isBool")]
async fn builtin_is_bool(co: GenCo, value: Value) -> Result<Value, ErrorKind> {
Ok(Value::Bool(matches!(value, Value::Bool(_))))
}
#[builtin("isFloat")]
async fn builtin_is_float(co: GenCo, value: Value) -> Result<Value, ErrorKind> {
Ok(Value::Bool(matches!(value, Value::Float(_))))
}
#[builtin("isFunction")]
async fn builtin_is_function(co: GenCo, value: Value) -> Result<Value, ErrorKind> {
Ok(Value::Bool(matches!(
value,
Value::Closure(_) | Value::Builtin(_)
)))
}
#[builtin("isInt")]
async fn builtin_is_int(co: GenCo, value: Value) -> Result<Value, ErrorKind> {
Ok(Value::Bool(matches!(value, Value::Integer(_))))
}
#[builtin("isList")]
async fn builtin_is_list(co: GenCo, value: Value) -> Result<Value, ErrorKind> {
Ok(Value::Bool(matches!(value, Value::List(_))))
}
#[builtin("isNull")]
async fn builtin_is_null(co: GenCo, value: Value) -> Result<Value, ErrorKind> {
Ok(Value::Bool(matches!(value, Value::Null)))
}
#[builtin("isPath")]
async fn builtin_is_path(co: GenCo, value: Value) -> Result<Value, ErrorKind> {
Ok(Value::Bool(matches!(value, Value::Path(_))))
}
#[builtin("isString")]
async fn builtin_is_string(co: GenCo, value: Value) -> Result<Value, ErrorKind> {
Ok(Value::Bool(matches!(value, Value::String(_))))
}
#[builtin("length")]
async fn builtin_length(co: GenCo, list: Value) -> Result<Value, ErrorKind> {
Ok(Value::Integer(list.to_list()?.len() as i64))
}
#[builtin("lessThan")]
async fn builtin_less_than(co: GenCo, x: Value, y: Value) -> Result<Value, ErrorKind> {
Ok(Value::Bool(matches!(
x.nix_cmp_ordering(y, co).await?,
Some(Ordering::Less)
)))
}
#[builtin("listToAttrs")]
async fn builtin_list_to_attrs(co: GenCo, list: Value) -> Result<Value, ErrorKind> {
let list = list.to_list()?;
let mut map = BTreeMap::new();
for val in list {
let attrs = generators::request_force(&co, val).await.to_attrs()?;
let name = generators::request_force(&co, attrs.select_required("name")?.clone())
.await
.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")]
async fn builtin_map(co: GenCo, f: Value, list: Value) -> Result<Value, ErrorKind> {
let mut out = imbl::Vector::<Value>::new();
// the best span we can getโฆ
let span = generators::request_span(&co).await;
for val in list.to_list()? {
let result = Value::Thunk(Thunk::new_suspended_call(f.clone(), val, span.clone()));
out.push_back(result)
}
Ok(Value::List(out.into()))
}
#[builtin("mapAttrs")]
async fn builtin_map_attrs(co: GenCo, f: Value, attrs: Value) -> Result<Value, ErrorKind> {
let attrs = attrs.to_attrs()?;
let mut out = imbl::OrdMap::new();
// the best span we can getโฆ
let span = generators::request_span(&co).await;
for (key, value) in attrs.into_iter() {
let result = Value::Thunk(Thunk::new_suspended_call(
f.clone(),
key.clone().into(),
span.clone(),
));
let result = Value::Thunk(Thunk::new_suspended_call(result, value, span.clone()));
out.insert(key, result);
}
Ok(Value::attrs(out.into()))
}
#[builtin("match")]
async fn builtin_match(co: GenCo, 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(Value::List(
caps.iter()
.skip(1)
.map(|grp| grp.map(|g| Value::from(g.as_str())).unwrap_or(Value::Null))
.collect::<imbl::Vector<Value>>()
.into(),
)),
None => Ok(Value::Null),
}
}
#[builtin("mul")]
async fn builtin_mul(co: GenCo, x: Value, y: Value) -> Result<Value, ErrorKind> {
arithmetic_op!(&x, &y, *)
}
#[builtin("parseDrvName")]
async fn builtin_parse_drv_name(co: GenCo, 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")]
async fn builtin_partition(co: GenCo, pred: Value, list: Value) -> Result<Value, ErrorKind> {
let mut right: imbl::Vector<Value> = Default::default();
let mut wrong: imbl::Vector<Value> = Default::default();
let list: NixList = list.to_list()?;
for elem in list {
let result = generators::request_call_with(&co, pred.clone(), [elem.clone()]).await;
if generators::request_force(&co, result).await.as_bool()? {
right.push_back(elem);
} else {
wrong.push_back(elem);
};
}
let res = [
("right", Value::List(NixList::from(right))),
("wrong", Value::List(NixList::from(wrong))),
];
Ok(Value::attrs(NixAttrs::from_iter(res.into_iter())))
}
#[builtin("removeAttrs")]
async fn builtin_remove_attrs(
co: GenCo,
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")]
async fn builtin_replace_strings(
co: GenCo,
from: Value,
to: Value,
s: Value,
) -> Result<Value, ErrorKind> {
let from = from.to_list()?;
for val in &from {
generators::request_force(&co, val.clone()).await;
}
let to = to.to_list()?;
for val in &to {
generators::request_force(&co, val.clone()).await;
}
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")]
async fn builtin_seq(co: GenCo, _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")]
async fn builtin_split(co: GenCo, 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")]
async fn builtin_sort(co: GenCo, comparator: Value, list: Value) -> Result<Value, ErrorKind> {
let list = list.to_list()?;
let sorted = list.sort_by(&co, comparator).await?;
Ok(Value::List(sorted))
}
#[builtin("splitVersion")]
async fn builtin_split_version(co: GenCo, 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")]
async fn builtin_string_length(co: GenCo, #[lazy] s: Value) -> Result<Value, ErrorKind> {
// also forces the value
let s = s.coerce_to_string(co, CoercionKind::Weak).await?;
Ok(Value::Integer(s.to_str()?.as_str().len() as i64))
}
#[builtin("sub")]
async fn builtin_sub(co: GenCo, x: Value, y: Value) -> Result<Value, ErrorKind> {
arithmetic_op!(&x, &y, -)
}
#[builtin("substring")]
async fn builtin_substring(
co: GenCo,
start: Value,
len: Value,
s: Value,
) -> Result<Value, ErrorKind> {
let beg = start.as_int()?;
let len = len.as_int()?;
let x = s.coerce_to_string(co, CoercionKind::Weak).await?.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()));
}
let end = if len < 0 {
x.as_str().len()
} else {
cmp::min(beg + (len as usize), x.as_str().len())
};
Ok(Value::String(x.as_bytes()[beg..end].try_into()?))
}
#[builtin("tail")]
async fn builtin_tail(co: GenCo, list: Value) -> Result<Value, ErrorKind> {
let xs = list.to_list()?;
if xs.is_empty() {
Err(ErrorKind::TailEmptyList)
} else {
let output = xs.into_iter().skip(1).collect::<Vec<_>>();
Ok(Value::List(NixList::construct(output.len(), output)))
}
}
#[builtin("throw")]
async fn builtin_throw(co: GenCo, message: Value) -> Result<Value, ErrorKind> {
Ok(Value::Catchable(CatchableErrorKind::Throw(
message.to_str()?.to_string(),
)))
}
#[builtin("toString")]
async fn builtin_to_string(co: GenCo, #[lazy] x: Value) -> Result<Value, ErrorKind> {
// coerce_to_string forces for us
x.coerce_to_string(co, CoercionKind::Strong).await
}
#[builtin("toXML")]
async fn builtin_to_xml(co: GenCo, value: Value) -> Result<Value, ErrorKind> {
let value = generators::request_deep_force(&co, value, SharedThunkSet::default()).await;
let mut buf: Vec<u8> = vec![];
to_xml::value_to_xml(&mut buf, &value)?;
Ok(String::from_utf8(buf)?.into())
}
#[builtin("placeholder")]
async fn builtin_placeholder(co: GenCo, #[lazy] _x: Value) -> Result<Value, ErrorKind> {
generators::emit_warning_kind(&co, WarningKind::NotImplemented("builtins.placeholder"))
.await;
Ok("<builtins.placeholder-is-not-implemented-in-tvix-yet>".into())
}
#[builtin("trace")]
async fn builtin_trace(co: GenCo, message: Value, value: Value) -> Result<Value, ErrorKind> {
// TODO(grfn): `trace` should be pluggable and capturable, probably via a method on
// the VM
eprintln!("trace: {} :: {}", message, message.type_of());
Ok(value)
}
#[builtin("toPath")]
async fn builtin_to_path(co: GenCo, s: Value) -> Result<Value, ErrorKind> {
match coerce_value_to_path(&co, s).await? {
Err(cek) => Ok(Value::Catchable(cek)),
Ok(path) => {
let path: Value = crate::value::canon_path(path).into();
Ok(path.coerce_to_string(co, CoercionKind::Weak).await?)
}
}
}
#[builtin("tryEval")]
async fn builtin_try_eval(co: GenCo, #[lazy] e: Value) -> Result<Value, ErrorKind> {
let res = match generators::request_try_force(&co, e).await {
Value::Catchable(_) => [("value", false.into()), ("success", false.into())],
value => [("value", value), ("success", true.into())],
};
Ok(Value::attrs(NixAttrs::from_iter(res.into_iter())))
}
#[builtin("typeOf")]
async fn builtin_type_of(co: GenCo, x: Value) -> Result<Value, ErrorKind> {
Ok(Value::String(x.type_of().into()))
}
}
/// Internal helper function for genericClosure, determining whether a
/// value has been seen before.
async fn bgc_insert_key(co: &GenCo, key: Value, done: &mut Vec<Value>) -> Result<bool, ErrorKind> {
for existing in done.iter() {
if generators::check_equality(
co,
existing.clone(),
key.clone(),
// TODO(tazjin): not actually sure which semantics apply here
PointerEquality::ForbidAll,
)
.await?
{
return Ok(false);
}
}
done.push(key);
Ok(true)
}
/// 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();
// Pure-value builtins
result.push(("nixVersion", Value::String("2.3-compat-tvix-0.1".into())));
result.push(("langVersion", Value::Integer(6)));
result.push(("null", Value::Null));
result.push(("true", Value::Bool(true)));
result.push(("false", Value::Bool(false)));
result.push((
"currentSystem",
crate::systems::llvm_triple_to_nix_double(CURRENT_PLATFORM).into(),
));
result
}
#[builtins]
mod placeholder_builtins {
use super::*;
#[builtin("unsafeDiscardStringContext")]
async fn builtin_unsafe_discard_string_context(
_: GenCo,
#[lazy] s: Value,
) -> Result<Value, ErrorKind> {
// Tvix does not manually track contexts, and this is a no-op for us.
Ok(s)
}
#[builtin("addErrorContext")]
async fn builtin_add_error_context(
co: GenCo,
#[lazy] _context: Value,
#[lazy] val: Value,
) -> Result<Value, ErrorKind> {
generators::emit_warning_kind(&co, WarningKind::NotImplemented("builtins.addErrorContext"))
.await;
Ok(val)
}
#[builtin("unsafeGetAttrPos")]
async fn builtin_unsafe_get_attr_pos(
co: GenCo,
_name: Value,
_attrset: Value,
) -> Result<Value, ErrorKind> {
generators::emit_warning_kind(
&co,
WarningKind::NotImplemented("builtins.unsafeGetAttrsPos"),
)
.await;
let res = [
("line", 42.into()),
("col", 42.into()),
("file", Value::Path(Box::new("/deep/thought".into()))),
];
Ok(Value::attrs(NixAttrs::from_iter(res.into_iter())))
}
}
pub fn placeholders() -> Vec<(&'static str, Value)> {
placeholder_builtins::builtins()
}
