diff options
| -rw-r--r-- | tvix/eval/src/errors.rs | 4 | ||||
| -rw-r--r-- | tvix/eval/src/vm.rs | 169 |
2 files changed, 134 insertions, 39 deletions
diff --git a/tvix/eval/src/errors.rs b/tvix/eval/src/errors.rs index 8a85972923c5..fb9f3b6ec589 100644 --- a/tvix/eval/src/errors.rs +++ b/tvix/eval/src/errors.rs @@ -6,6 +6,10 @@ pub enum Error { key: String, }, + InvalidKeyType { + given: &'static str, + }, + TypeError { expected: &'static str, actual: &'static str, diff --git a/tvix/eval/src/vm.rs b/tvix/eval/src/vm.rs index 0c8ea4ffd1f6..b81281cf5194 100644 --- a/tvix/eval/src/vm.rs +++ b/tvix/eval/src/vm.rs @@ -17,18 +17,20 @@ pub struct VM { } impl VM { - fn push(&mut self, value: Value) { - self.stack.push(value) - } - - fn pop(&mut self) -> Value { - self.stack.pop().expect("TODO") + fn inc_ip(&mut self) -> OpCode { + let op = self.chunk.code[self.ip]; + self.ip += 1; + op } fn peek(&self, at: usize) -> &Value { &self.stack[self.stack.len() - 1 - at] } + fn pop(&mut self) -> Value { + self.stack.pop().expect("TODO") + } + fn pop_number_pair(&mut self) -> EvalResult<NumberPair> { let v2 = self.pop(); let v1 = self.pop(); @@ -53,10 +55,8 @@ impl VM { } } - fn inc_ip(&mut self) -> OpCode { - let op = self.chunk.code[self.ip]; - self.ip += 1; - op + fn push(&mut self, value: Value) { + self.stack.push(value) } fn run(&mut self) -> EvalResult<Value> { @@ -132,6 +132,24 @@ impl VM { } } + // Construct runtime representation of an attr path (essentially + // just a list of strings). + // + // The difference to the list construction operation is that this + // forces all elements into strings, as attribute set keys are + // required to be strict in Nix. + fn run_attr_path(&mut self, count: usize) -> EvalResult<()> { + debug_assert!(count > 1, "AttrPath needs at least two fragments"); + let mut path = Vec::with_capacity(count); + + for _ in 0..count { + path.push(self.pop().as_string()?); + } + + self.push(Value::AttrPath(path)); + Ok(()) + } + fn run_attrset(&mut self, count: usize) -> EvalResult<()> { // If the attribute count happens to be 2, we might be able to // create the optimised name/value struct instead. @@ -210,33 +228,52 @@ impl VM { for _ in 0..count { let value = self.pop(); - let key = self.pop().as_string()?; // TODO(tazjin): attrpath - if attrs.insert(key.clone(), value).is_some() { - return Err(Error::DuplicateAttrsKey { key: key.0 }); + // It is at this point that nested attribute sets need to + // be constructed (if they exist). + // + let key = self.pop(); + match key { + Value::String(ks) => { + // TODO(tazjin): try_insert (rust#82766) or entry API + if attrs.insert(ks.clone(), value).is_some() { + return Err(Error::DuplicateAttrsKey { key: ks.0 }); + } + } + + Value::AttrPath(mut path) => { + set_nested_attr( + &mut attrs, + path.pop().expect("AttrPath is never empty"), + path, + value, + )?; + } + + other => { + return Err(Error::InvalidKeyType { + given: other.type_of(), + }) + } } } // TODO(tazjin): extend_reserve(count) (rust#72631) - self.push(Value::Attrs(Rc::new(NixAttrs::Map(attrs)))); Ok(()) } - // Construct runtime representation of an attr path (essentially - // just a list of strings). - // - // The difference to the list construction operation is that this - // forces all elements into strings, as attribute set keys are - // required to be strict in Nix. - fn run_attr_path(&mut self, count: usize) -> EvalResult<()> { - let mut path = vec![NixString(String::new()); count]; + // Interpolate string fragments by popping the specified number of + // fragments of the stack, evaluating them to strings, and pushing + // the concatenated result string back on the stack. + fn run_interpolate(&mut self, count: usize) -> EvalResult<()> { + let mut out = String::new(); - for idx in 0..count { - path[count - idx - 1] = self.pop().as_string()? + for _ in 0..count { + out.push_str(&self.pop().as_string()?.0); } - self.push(Value::AttrPath(path)); + self.push(Value::String(NixString(out))); Ok(()) } @@ -254,20 +291,6 @@ impl VM { self.push(Value::List(NixList(list))); Ok(()) } - - // Interpolate string fragments by popping the specified number of - // fragments of the stack, evaluating them to strings, and pushing - // the concatenated result string back on the stack. - fn run_interpolate(&mut self, count: usize) -> EvalResult<()> { - let mut out = String::new(); - - for _ in 0..count { - out.push_str(&self.pop().as_string()?.0); - } - - self.push(Value::String(NixString(out))); - Ok(()) - } } #[derive(Clone, Copy, Debug, PartialEq)] @@ -276,6 +299,74 @@ pub enum NumberPair { Integer(i64, i64), } +// Set a nested attribute inside of an attribute set, throwing a +// duplicate key error if a non-hashmap entry already exists on the +// path. +// +// There is some optimisation potential for this simple implementation +// if it becomes a problem. +fn set_nested_attr( + attrs: &mut BTreeMap<NixString, Value>, + key: NixString, + mut path: Vec<NixString>, + value: Value, +) -> EvalResult<()> { + let entry = attrs.entry(key); + + // If there is no next key we are at the point where we + // should insert the value itself. + if path.is_empty() { + match entry { + std::collections::btree_map::Entry::Occupied(entry) => { + return Err(Error::DuplicateAttrsKey { + key: entry.key().0.clone(), + }) + } + + std::collections::btree_map::Entry::Vacant(entry) => { + entry.insert(value); + return Ok(()); + } + }; + } + + // If there is not we go one step further down, in which case we + // need to ensure that there either is no entry, or the existing + // entry is a hashmap into which to insert the next value. + // + // If a value of a different type exists, the user specified a + // duplicate key. + match entry { + // Vacant entry -> new attribute set is needed. + std::collections::btree_map::Entry::Vacant(entry) => { + let mut map = BTreeMap::new(); + + // TODO(tazjin): technically recursing further is not + // required, we can create the whole hierarchy here, but + // it's noisy. + set_nested_attr(&mut map, path.pop().expect("next key exists"), path, value)?; + + entry.insert(Value::Attrs(Rc::new(NixAttrs::Map(map)))); + } + + // Occupied entry: Either error out if there is something + // other than attrs, or insert the next value. + std::collections::btree_map::Entry::Occupied(mut entry) => match entry.get_mut() { + Value::Attrs(_attrs) => { + todo!("implement mutable attrsets") + } + + _ => { + return Err(Error::DuplicateAttrsKey { + key: entry.key().0.clone(), + }) + } + }, + } + + Ok(()) +} + pub fn run_chunk(chunk: Chunk) -> EvalResult<Value> { let mut vm = VM { chunk, |