feat(tvix/eval): use EvalIO::import_path when coercing paths

This "ties the knot" of importing files into a store when referring
to them through path literals, e.g. inside of strings.

I'm not yet sure if this interface is sufficient for
builtins.path (which we haven't implemented at all yet), but it's
enough to wire up eval & store initially.

In the default implementations nothing interesting happens in this
function at all.

Change-Id: Ie01ff4161617d1e743a68dbd1a5e54c1b40c0990
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7582
Reviewed-by: grfn <grfn@gws.fyi>
Tested-by: BuildkiteCI
This commit is contained in:
Vincent Ambo 2022-12-13 00:12:13 +03:00 committed by tazjin
parent edd13573f5
commit 270b1084e8
3 changed files with 28 additions and 3 deletions

View file

@ -16,7 +16,7 @@
//! how store paths are opened and so on.
use smol_str::SmolStr;
use std::path::PathBuf;
use std::path::{Path, PathBuf};
use std::rc::Rc;
use crate::errors::ErrorKind;
@ -42,6 +42,15 @@ pub trait EvalIO {
/// of its entries associated with their [`FileType`].
fn read_dir(&self, path: PathBuf) -> Result<Vec<(SmolStr, FileType)>, ErrorKind>;
/// Import the given path. What this means depends on the
/// implementation, for example for a `std::io`-based
/// implementation this might be a no-op, while for a Tvix store
/// this might be a copy of the given files to the store.
///
/// This is primarily used in the context of things like coercing
/// a local path to a string, or builtins like `path`.
fn import_path(&self, path: &Path) -> Result<PathBuf, ErrorKind>;
/// Returns the root of the store directory, if such a thing
/// exists in the evaluation context.
fn store_dir(&self) -> Option<String> {
@ -103,6 +112,12 @@ impl EvalIO for StdIO {
Ok(result)
}
// this is a no-op for `std::io`, as the user can already refer to
// the path directly
fn import_path(&self, path: &Path) -> Result<PathBuf, ErrorKind> {
Ok(path.to_path_buf())
}
}
/// Dummy implementation of [`EvalIO`], can be used in contexts where
@ -127,4 +142,10 @@ impl EvalIO for DummyIO {
"I/O methods are not implemented in DummyIO",
))
}
fn import_path(&self, _: &Path) -> Result<PathBuf, ErrorKind> {
Err(ErrorKind::NotImplemented(
"I/O methods are not implemented in DummyIO",
))
}
}

View file

@ -185,7 +185,8 @@ impl Value {
// sequences without NUL bytes, whereas Tvix only allows valid
// Unicode. See also b/189.
(Value::Path(p), kind) if kind != CoercionKind::ThunksOnly => {
Ok(p.to_string_lossy().into_owned().into())
let imported = vm.io().import_path(p)?;
Ok(imported.to_string_lossy().into_owned().into())
}
// Attribute sets can be converted to strings if they either have an

View file

@ -40,7 +40,10 @@ fn nix_eval(expr: &str) -> String {
#[track_caller]
fn compare_eval(expr: &str) {
let nix_result = nix_eval(expr);
let tvix_result = tvix_eval::Evaluation::new(expr, None)
let mut eval = tvix_eval::Evaluation::new(expr, None);
eval.io_handle = Box::new(tvix_eval::StdIO);
let tvix_result = eval
.evaluate()
.value
.expect("tvix evaluation should succeed")