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refactor(tvix/eval): move __toString calling to a helper function

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It turns out that this is used not just in coerceToString, but also in
toJSON.

Change-Id: I1c324b115a0b8bb6d83446d5bf70453c9b90685e
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8203
Tested-by: BuildkiteCI
Reviewed-by: raitobezarius <tvl@lahfa.xyz>
This commit is contained in:
Vincent Ambo 2023-03-03 23:45:12 +03:00 committed by tazjin
parent 54a12577c4
commit a9f44721e5
2 changed files with 35 additions and 25 deletions
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26
tvix/eval/src/value/attrs.rs
View file

@ -15,9 +15,11 @@ use serde::{Deserialize, Serialize};
use super::string::NixString;
use super::thunk::ThunkSet;
use super::CoercionKind;
use super::TotalDisplay;
use super::Value;
use crate::errors::ErrorKind;
use crate::generators::{self, GenCo};
lazy_static! {
static ref NAME_S: NixString = "name".into();
@ -396,6 +398,30 @@ impl NixAttrs {
pub(crate) fn from_kv(name: Value, value: Value) -> Self {
NixAttrs(AttrsRep::KV { name, value })
}
/// Attempt to coerce an attribute set with a `__toString`
/// attribute to a string.
pub(crate) async fn try_to_string(&self, co: &GenCo, kind: CoercionKind) -> Option<NixString> {
if let Some(to_string) = self.select("__toString") {
let callable = generators::request_force(&co, to_string.clone()).await;
// Leave the attribute set on the stack as an argument
// to the function call.
generators::request_stack_push(&co, Value::Attrs(Box::new(self.clone()))).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;
return Some(s);
}
None
}
}
/// In Nix, name/value attribute pairs are frequently constructed from

34
tvix/eval/src/value/mod.rs
View file

@ -265,32 +265,16 @@ impl Value {
// set itself or an `outPath` attribute which should be a string.
// `__toString` is preferred.
(Value::Attrs(attrs), kind) => {
match (attrs.select("__toString"), attrs.select("outPath")) {
(None, None) => Err(ErrorKind::NotCoercibleToString { from: "set", kind }),
(Some(f), _) => {
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)) => {
let s = generators::request_string_coerce(&co, s.clone(), kind).await;
Ok(Value::String(s))
}
if let Some(s) = attrs.try_to_string(&co, kind).await {
return Ok(Value::String(s));
}
if let Some(out_path) = attrs.select("outPath") {
let s = generators::request_string_coerce(&co, out_path.clone(), kind).await;
return Ok(Value::String(s));
}
Err(ErrorKind::NotCoercibleToString { from: "set", kind })
}
// strong coercions