refactor(tvix/eval): add VM::call_value helper method

This makes it possible to call a callable value (builtin or
closure/lambda) directly, without unwrapping it first. This is needed
for pretty much all higher-order functions to work correctly.

This is mostly equivalent to the previous code in coerce_to_string for
calling `__toString`, except it expects the argument(s) to already be
placed on the stack.

Note that the span for the `NotCallable` error is not currently
guaranteed to make any sense, will experiment with this.

Change-Id: I821224368d438a28900858b343defc1817e46a0a
Reviewed-on: https://cl.tvl.fyi/c/depot/+/6717
Tested-by: BuildkiteCI
Reviewed-by: sterni <sternenseemann@systemli.org>
This commit is contained in:
Vincent Ambo 2022-09-21 00:32:49 +03:00 committed by tazjin
parent f600aa5322
commit 8f2004d360
5 changed files with 32 additions and 34 deletions

View file

@ -12,8 +12,7 @@ use std::{
use crate::{ use crate::{
errors::ErrorKind, errors::ErrorKind,
upvalues::UpvalueCarrier, value::{Builtin, CoercionKind, NixAttrs, NixList, NixString, Value},
value::{Builtin, Closure, CoercionKind, NixAttrs, NixList, NixString, Value},
vm::VM, vm::VM,
}; };
@ -147,14 +146,13 @@ fn pure_builtins() -> Vec<Builtin> {
}), }),
Builtin::new("map", &[true, true], |args, vm| { Builtin::new("map", &[true, true], |args, vm| {
let list: NixList = args[1].to_list()?; let list: NixList = args[1].to_list()?;
let func: Closure = args[0].to_closure()?;
list.into_iter() list.into_iter()
.map(|val| { .map(|val| {
// Leave the argument on the stack before calling the // Leave the argument on the stack before calling the
// function. // function.
vm.push(val); vm.push(val);
vm.call(func.lambda(), func.upvalues().clone(), 1) vm.call_value(&args[0])
}) })
.collect::<Result<Vec<Value>, _>>() .collect::<Result<Vec<Value>, _>>()
.map(|list| Value::List(NixList::from(list))) .map(|list| Value::List(NixList::from(list)))

View file

@ -1 +1 @@
[ [ 1 2 3 4 5 ] [ 2 4 6 8 10 ] [ 2 4 6 8 10 ] [ 1 2 3 4 5 ] ] [ [ 1 2 3 4 5 ] [ 2 4 6 8 10 ] [ 2 4 6 8 10 ] [ 2 4 6 8 10 ] [ 1 2 3 4 5 ] ]

View file

@ -11,6 +11,9 @@
in builtins.map (x: x * n) [ 1 2 3 4 5 ] in builtins.map (x: x * n) [ 1 2 3 4 5 ]
) )
# same, but with a builtin
(builtins.map (builtins.mul 2) [ 1 2 3 4 5 ])
# from global scope # from global scope
(map (x: x) [ 1 2 3 4 5 ]) (map (x: x) [ 1 2 3 4 5 ])
] ]

View file

@ -16,7 +16,6 @@ mod thunk;
use crate::errors::ErrorKind; use crate::errors::ErrorKind;
use crate::opcode::StackIdx; use crate::opcode::StackIdx;
use crate::upvalues::UpvalueCarrier;
use crate::vm::VM; use crate::vm::VM;
pub use attrs::NixAttrs; pub use attrs::NixAttrs;
pub use builtin::Builtin; pub use builtin::Builtin;
@ -155,22 +154,9 @@ impl Value {
(Some(f), _) => { (Some(f), _) => {
// use a closure here to deal with the thunk borrow we need to do below // use a closure here to deal with the thunk borrow we need to do below
let call_to_string = |value: &Value, vm: &mut VM| { let call_to_string = |value: &Value, vm: &mut VM| {
// TODO(sterni): calling logic should be extracted into a helper // Leave self on the stack as an argument to the function call.
let result = match value { vm.push(self.clone());
Value::Closure(c) => { let result = vm.call_value(value)?;
vm.push(self.clone());
vm.call(c.lambda(), c.upvalues().clone(), 1)
.map_err(|e| e.kind)
}
Value::Builtin(b) => {
vm.push(self.clone());
vm.call_builtin(b.clone()).map_err(|e| e.kind)?;
Ok(vm.pop())
}
_ => Err(ErrorKind::NotCallable),
}?;
match result { match result {
Value::String(s) => Ok(s), Value::String(s) => Ok(s),

View file

@ -175,7 +175,28 @@ impl<'o> VM<'o> {
} }
} }
#[allow(clippy::let_and_return)] // due to disassembler /// Execute the given value in this VM's context, if it is a
/// callable.
///
/// The stack of the VM must be prepared with all required
/// arguments before calling this and the value must have already
/// been forced.
pub fn call_value(&mut self, callable: &Value) -> EvalResult<Value> {
match callable {
Value::Closure(c) => self.call(c.lambda(), c.upvalues().clone(), 1),
Value::Builtin(b) => {
self.call_builtin(b.clone())?;
Ok(self.pop())
}
Value::Thunk(t) => self.call_value(&t.value()),
// TODO: this isn't guaranteed to be a useful span, actually
_ => Err(self.error(ErrorKind::NotCallable)),
}
}
/// Execute the given lambda in this VM's context, returning its /// Execute the given lambda in this VM's context, returning its
/// value after its stack frame completes. /// value after its stack frame completes.
pub fn call( pub fn call(
@ -456,17 +477,7 @@ impl<'o> VM<'o> {
OpCode::OpCall => { OpCode::OpCall => {
let callable = self.pop(); let callable = self.pop();
match callable { self.call_value(&callable)?;
Value::Closure(closure) => {
let result =
self.call(closure.lambda(), closure.upvalues().clone(), 1)?;
self.push(result)
}
Value::Builtin(builtin) => self.call_builtin(builtin)?,
_ => return Err(self.error(ErrorKind::NotCallable)),
};
} }
OpCode::OpTailCall => { OpCode::OpTailCall => {