diff options
Diffstat (limited to 'tvix/eval/src/value/mod.rs')
| -rw-r--r-- | tvix/eval/src/value/mod.rs | 401 |
1 files changed, 154 insertions, 247 deletions
diff --git a/tvix/eval/src/value/mod.rs b/tvix/eval/src/value/mod.rs index a869c01675..81e5373132 100644 --- a/tvix/eval/src/value/mod.rs +++ b/tvix/eval/src/value/mod.rs @@ -1,11 +1,12 @@ //! This module implements the backing representation of runtime //! values in the Nix language. use std::cmp::Ordering; +use std::fmt::Display; +use std::future::Future; use std::num::{NonZeroI32, NonZeroUsize}; -use std::ops::Deref; use std::path::PathBuf; +use std::pin::Pin; use std::rc::Rc; -use std::{cell::Ref, fmt::Display}; use lexical_core::format::CXX_LITERAL; use serde::{Deserialize, Serialize}; @@ -20,12 +21,12 @@ mod path; mod string; mod thunk; -use crate::errors::{AddContext, ErrorKind}; +use crate::errors::ErrorKind; use crate::opcode::StackIdx; use crate::vm::generators::{self, GenCo}; -use crate::vm::VM; +use crate::AddContext; pub use attrs::NixAttrs; -pub use builtin::{Builtin, BuiltinArgument}; +pub use builtin::{Builtin, BuiltinResult}; pub(crate) use function::Formals; pub use function::{Closure, Lambda}; pub use list::NixList; @@ -139,8 +140,6 @@ macro_rules! gen_is { /// Describes what input types are allowed when coercing a `Value` to a string #[derive(Clone, Copy, PartialEq, Debug)] pub enum CoercionKind { - /// Force thunks, but perform no other coercions. - ThunksOnly, /// Only coerce already "stringly" types like strings and paths, but also /// coerce sets that have a `__toString` attribute. Equivalent to /// `!coerceMore` in C++ Nix. @@ -151,26 +150,6 @@ pub enum CoercionKind { Strong, } -/// A reference to a [`Value`] returned by a call to [`Value::force`], whether the value was -/// originally a thunk or not. -/// -/// Implements [`Deref`] to [`Value`], so can generally be used as a [`Value`] -pub enum ForceResult<'a> { - ForcedThunk(Ref<'a, Value>), - Immediate(&'a Value), -} - -impl<'a> Deref for ForceResult<'a> { - type Target = Value; - - fn deref(&self) -> &Self::Target { - match self { - ForceResult::ForcedThunk(r) => r, - ForceResult::Immediate(v) => v, - } - } -} - impl<T> From<T> for Value where T: Into<NixString>, @@ -204,33 +183,80 @@ pub enum PointerEquality { } impl Value { + /// Deeply forces a value, traversing e.g. lists and attribute sets and forcing + /// their contents, too. + /// + /// This is a generator function. + pub(super) async fn deep_force( + self, + co: GenCo, + thunk_set: SharedThunkSet, + ) -> Result<Value, ErrorKind> { + // Get rid of any top-level thunks, and bail out of self-recursive + // thunks. + let value = if let Value::Thunk(ref t) = &self { + if !thunk_set.insert(t) { + return Ok(self); + } + generators::request_force(&co, self).await + } else { + self + }; + + match &value { + // Short-circuit on already evaluated values, or fail on internal values. + Value::Null + | Value::Bool(_) + | Value::Integer(_) + | Value::Float(_) + | Value::String(_) + | Value::Path(_) + | Value::Closure(_) + | Value::Builtin(_) => return Ok(value), + + Value::List(list) => { + for val in list { + generators::request_deep_force(&co, val.clone(), thunk_set.clone()).await; + } + } + + Value::Attrs(attrs) => { + for (_, val) in attrs.iter() { + generators::request_deep_force(&co, val.clone(), thunk_set.clone()).await; + } + } + + Value::Thunk(_) => panic!("Tvix bug: force_value() returned a thunk"), + + Value::AttrNotFound + | Value::Blueprint(_) + | Value::DeferredUpvalue(_) + | Value::UnresolvedPath(_) => panic!( + "Tvix bug: internal value left on stack: {}", + value.type_of() + ), + }; + + Ok(value) + } + /// Coerce a `Value` to a string. See `CoercionKind` for a rundown of what /// input types are accepted under what circumstances. - pub fn coerce_to_string( - &self, - kind: CoercionKind, - vm: &mut VM, - ) -> Result<NixString, ErrorKind> { - // TODO: eventually, this will need to handle string context and importing - // files into the Nix store depending on what context the coercion happens in - if let Value::Thunk(t) = self { - t.force(vm)?; - } - - match (self, kind) { - // deal with thunks - (Value::Thunk(t), _) => t.value().coerce_to_string(kind, vm), + pub async fn coerce_to_string(self, co: GenCo, kind: CoercionKind) -> Result<Value, ErrorKind> { + let value = generators::request_force(&co, self).await; + match (value, kind) { // coercions that are always done - (Value::String(s), _) => Ok(s.clone()), + tuple @ (Value::String(_), _) => Ok(tuple.0), // TODO(sterni): Think about proper encoding handling here. This needs // general consideration anyways, since one current discrepancy between // C++ Nix and Tvix is that the former's strings are arbitrary byte // sequences without NUL bytes, whereas Tvix only allows valid // Unicode. See also b/189. - (Value::Path(p), kind) if kind != CoercionKind::ThunksOnly => { - let imported = vm.io().import_path(p)?; + (Value::Path(p), _) => { + // TODO(tazjin): there are cases where coerce_to_string does not import + let imported = generators::request_path_import(&co, p).await; Ok(imported.to_string_lossy().into_owned().into()) } @@ -238,38 +264,32 @@ impl Value { // `__toString` attribute which holds a function that receives the // set itself or an `outPath` attribute which should be a string. // `__toString` is preferred. - (Value::Attrs(attrs), kind) if kind != CoercionKind::ThunksOnly => { + (Value::Attrs(attrs), kind) => { match (attrs.select("__toString"), attrs.select("outPath")) { (None, None) => Err(ErrorKind::NotCoercibleToString { from: "set", kind }), (Some(f), _) => { - // use a closure here to deal with the thunk borrow we need to do below - let call_to_string = |value: &Value, vm: &mut VM| { - // Leave self on the stack as an argument to the function call. - vm.push(self.clone()); - vm.call_value(value)?; - let result = vm.pop(); - - match result { - Value::String(s) => Ok(s), - // Attribute set coercion actually works - // recursively, e.g. you can even return - // /another/ set with a __toString attr. - _ => result.coerce_to_string(kind, vm), - } - }; - - if let Value::Thunk(t) = f { - t.force(vm)?; - let guard = t.value(); - call_to_string(&guard, vm) - } else { - call_to_string(f, vm) - } + let callable = generators::request_force(&co, f.clone()).await; + + // Leave the attribute set on the stack as an argument + // to the function call. + generators::request_stack_push(&co, Value::Attrs(attrs)).await; + + // Call the callable ... + let result = generators::request_call(&co, callable).await; + + // Recurse on the result, as attribute set coercion + // actually works recursively, e.g. you can even return + // /another/ set with a __toString attr. + let s = generators::request_string_coerce(&co, result, kind).await; + Ok(Value::String(s)) } // Similarly to `__toString` we also coerce recursively for `outPath` - (None, Some(s)) => s.coerce_to_string(kind, vm), + (None, Some(s)) => { + let s = generators::request_string_coerce(&co, s.clone(), kind).await; + Ok(Value::String(s)) + } } } @@ -287,30 +307,31 @@ impl Value { } // Lists are coerced by coercing their elements and interspersing spaces - (Value::List(l), CoercionKind::Strong) => { - // TODO(sterni): use intersperse when it becomes available? - // https://github.com/rust-lang/rust/issues/79524 - l.iter() - .map(|v| v.coerce_to_string(kind, vm)) - .reduce(|acc, string| { - let a = acc?; - let s = &string?; - Ok(a.concat(&" ".into()).concat(s)) - }) - // None from reduce indicates empty iterator - .unwrap_or_else(|| Ok("".into())) + (Value::List(list), CoercionKind::Strong) => { + let mut out = String::new(); + + for (idx, elem) in list.into_iter().enumerate() { + if idx > 0 { + out.push(' '); + } + + let s = generators::request_string_coerce(&co, elem, kind).await; + out.push_str(s.as_str()); + } + + Ok(Value::String(out.into())) } - (Value::Path(_), _) - | (Value::Attrs(_), _) - | (Value::Closure(_), _) - | (Value::Builtin(_), _) - | (Value::Null, _) - | (Value::Bool(_), _) - | (Value::Integer(_), _) - | (Value::Float(_), _) - | (Value::List(_), _) => Err(ErrorKind::NotCoercibleToString { - from: self.type_of(), + (Value::Thunk(_), _) => panic!("Tvix bug: force returned unforced thunk"), + + val @ (Value::Closure(_), _) + | val @ (Value::Builtin(_), _) + | val @ (Value::Null, _) + | val @ (Value::Bool(_), _) + | val @ (Value::Integer(_), _) + | val @ (Value::Float(_), _) + | val @ (Value::List(_), _) => Err(ErrorKind::NotCoercibleToString { + from: val.0.type_of(), kind, }), @@ -333,7 +354,7 @@ impl Value { /// The `top_level` parameter controls whether this invocation is the top-level /// comparison, or a nested value comparison. See /// `//tvix/docs/value-pointer-equality.md` - pub(crate) async fn neo_nix_eq( + pub(crate) async fn nix_eq( self, other: Value, co: GenCo, @@ -530,49 +551,52 @@ impl Value { gen_is!(is_number, Value::Integer(_) | Value::Float(_)); gen_is!(is_bool, Value::Bool(_)); - /// Compare `self` against `other` for equality using Nix equality semantics. - /// - /// Takes a reference to the `VM` to allow forcing thunks during comparison - pub fn nix_eq(&self, other: &Self, vm: &mut VM) -> Result<bool, ErrorKind> { - match (self, other) { - // Trivial comparisons - (Value::Null, Value::Null) => Ok(true), - (Value::Bool(b1), Value::Bool(b2)) => Ok(b1 == b2), - (Value::String(s1), Value::String(s2)) => Ok(s1 == s2), - (Value::Path(p1), Value::Path(p2)) => Ok(p1 == p2), - - // Numerical comparisons (they work between float & int) - (Value::Integer(i1), Value::Integer(i2)) => Ok(i1 == i2), - (Value::Integer(i), Value::Float(f)) => Ok(*i as f64 == *f), - (Value::Float(f1), Value::Float(f2)) => Ok(f1 == f2), - (Value::Float(f), Value::Integer(i)) => Ok(*i as f64 == *f), - - (Value::Attrs(_), Value::Attrs(_)) - | (Value::List(_), Value::List(_)) - | (Value::Thunk(_), _) - | (_, Value::Thunk(_)) => Ok(vm.nix_eq(self.clone(), other.clone(), false)?), - - // Everything else is either incomparable (e.g. internal - // types) or false. - _ => Ok(false), - } + /// Internal helper to allow `nix_cmp_ordering` to recurse. + fn nix_cmp_boxed( + self, + other: Self, + co: GenCo, + ) -> Pin<Box<dyn Future<Output = Result<Option<Ordering>, ErrorKind>>>> { + Box::pin(self.nix_cmp_ordering(other, co)) } /// Compare `self` against other using (fallible) Nix ordering semantics. - pub fn nix_cmp(&self, other: &Self, vm: &mut VM) -> Result<Option<Ordering>, ErrorKind> { + /// + /// Note that as this returns an `Option<Ordering>` it can not directly be + /// used as a generator function in the VM. The exact use depends on the + /// callsite, as the meaning is interpreted in different ways e.g. based on + /// the comparison operator used. + /// + /// The function is intended to be used from within other generator + /// functions or `gen!` blocks. + pub async fn nix_cmp_ordering( + self, + other: Self, + co: GenCo, + ) -> Result<Option<Ordering>, ErrorKind> { match (self, other) { // same types - (Value::Integer(i1), Value::Integer(i2)) => Ok(i1.partial_cmp(i2)), - (Value::Float(f1), Value::Float(f2)) => Ok(f1.partial_cmp(f2)), - (Value::String(s1), Value::String(s2)) => Ok(s1.partial_cmp(s2)), + (Value::Integer(i1), Value::Integer(i2)) => Ok(i1.partial_cmp(&i2)), + (Value::Float(f1), Value::Float(f2)) => Ok(f1.partial_cmp(&f2)), + (Value::String(s1), Value::String(s2)) => Ok(s1.partial_cmp(&s2)), (Value::List(l1), Value::List(l2)) => { for i in 0.. { if i == l2.len() { return Ok(Some(Ordering::Greater)); } else if i == l1.len() { return Ok(Some(Ordering::Less)); - } else if !vm.nix_eq(l1[i].clone(), l2[i].clone(), true)? { - return l1[i].force(vm)?.nix_cmp(&*l2[i].force(vm)?, vm); + } else if !generators::check_equality( + &co, + l1[i].clone(), + l2[i].clone(), + PointerEquality::AllowAll, + ) + .await? + { + // TODO: do we need to control `top_level` here? + let v1 = generators::request_force(&co, l1[i].clone()).await; + let v2 = generators::request_force(&co, l2[i].clone()).await; + return v1.nix_cmp_boxed(v2, co).await; } } @@ -580,8 +604,8 @@ impl Value { } // different types - (Value::Integer(i1), Value::Float(f2)) => Ok((*i1 as f64).partial_cmp(f2)), - (Value::Float(f1), Value::Integer(i2)) => Ok(f1.partial_cmp(&(*i2 as f64))), + (Value::Integer(i1), Value::Float(f2)) => Ok((i1 as f64).partial_cmp(&f2)), + (Value::Float(f1), Value::Integer(i2)) => Ok(f1.partial_cmp(&(i2 as f64))), // unsupported types (lhs, rhs) => Err(ErrorKind::Incomparable { @@ -591,58 +615,12 @@ impl Value { } } - /// Ensure `self` is forced if it is a thunk, and return a reference to the resulting value. - pub fn force(&self, vm: &mut VM) -> Result<ForceResult, ErrorKind> { - match self { - Self::Thunk(thunk) => { - thunk.force(vm)?; - Ok(ForceResult::ForcedThunk(thunk.value())) - } - _ => Ok(ForceResult::Immediate(self)), + pub async fn force(self, co: GenCo) -> Result<Value, ErrorKind> { + if let Value::Thunk(thunk) = self { + return thunk.force(co).await; } - } - - /// Ensure `self` is *deeply* forced, including all recursive sub-values - pub(crate) fn deep_force( - &self, - vm: &mut VM, - thunk_set: &mut ThunkSet, - ) -> Result<(), ErrorKind> { - match self { - Value::Null - | Value::Bool(_) - | Value::Integer(_) - | Value::Float(_) - | Value::String(_) - | Value::Path(_) - | Value::Closure(_) - | Value::Builtin(_) - | Value::AttrNotFound - | Value::Blueprint(_) - | Value::DeferredUpvalue(_) - | Value::UnresolvedPath(_) => Ok(()), - Value::Attrs(a) => { - for (_, v) in a.iter() { - v.deep_force(vm, thunk_set)?; - } - Ok(()) - } - Value::List(l) => { - for val in l { - val.deep_force(vm, thunk_set)?; - } - Ok(()) - } - Value::Thunk(thunk) => { - if !thunk_set.insert(thunk) { - return Ok(()); - } - thunk.force(vm)?; - let value = thunk.value().clone(); - value.deep_force(vm, thunk_set) - } - } + Ok(self) } /// Explain a value in a human-readable way, e.g. by presenting @@ -835,9 +813,6 @@ fn type_error(expected: &'static str, actual: &Value) -> ErrorKind { #[cfg(test)] mod tests { - use super::*; - use imbl::vector; - mod floats { use crate::value::total_fmt_float; @@ -865,72 +840,4 @@ mod tests { } } } - - mod nix_eq { - use crate::observer::NoOpObserver; - - use super::*; - use proptest::prelude::ProptestConfig; - use test_strategy::proptest; - - #[proptest(ProptestConfig { cases: 5, ..Default::default() })] - fn reflexive(x: Value) { - let mut observer = NoOpObserver {}; - let mut vm = VM::new( - Default::default(), - Box::new(crate::DummyIO), - &mut observer, - Default::default(), - ); - - assert!(x.nix_eq(&x, &mut vm).unwrap()) - } - - #[proptest(ProptestConfig { cases: 5, ..Default::default() })] - fn symmetric(x: Value, y: Value) { - let mut observer = NoOpObserver {}; - let mut vm = VM::new( - Default::default(), - Box::new(crate::DummyIO), - &mut observer, - Default::default(), - ); - - assert_eq!( - x.nix_eq(&y, &mut vm).unwrap(), - y.nix_eq(&x, &mut vm).unwrap() - ) - } - - #[proptest(ProptestConfig { cases: 5, ..Default::default() })] - fn transitive(x: Value, y: Value, z: Value) { - let mut observer = NoOpObserver {}; - let mut vm = VM::new( - Default::default(), - Box::new(crate::DummyIO), - &mut observer, - Default::default(), - ); - - if x.nix_eq(&y, &mut vm).unwrap() && y.nix_eq(&z, &mut vm).unwrap() { - assert!(x.nix_eq(&z, &mut vm).unwrap()) - } - } - - #[test] - fn list_int_float_fungibility() { - let mut observer = NoOpObserver {}; - let mut vm = VM::new( - Default::default(), - Box::new(crate::DummyIO), - &mut observer, - Default::default(), - ); - - let v1 = Value::List(NixList::from(vector![Value::Integer(1)])); - let v2 = Value::List(NixList::from(vector![Value::Float(1.0)])); - - assert!(v1.nix_eq(&v2, &mut vm).unwrap()) - } - } } |