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daaa78056a
Under this design, *all* databases are a `DatabaseImpl<U>`, where the `U` implements `UserData` (you can use `()` if there is none). Code would default to `&dyn salsa::Database` but if you want to give access to the userdata, you can define a custom database trait `MyDatabase: salsa::Databse` so long as you * annotate `MyDatabase` trait definition of impls of `MyDatabase` with `#[salsa::db]` * implement `MyDatabase` for `DatabaseImpl<U>` where `U` is your userdata (this could be a blanket impl, if you don't know the precise userdata type). The `tests/common/mod.rs` shows the pattern.
53 lines
1.2 KiB
Rust
53 lines
1.2 KiB
Rust
//! Test for a tracked struct where the id field has a
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//! very poorly chosen hash impl (always returns 0).
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//! This demonstrates that the `#[id]` fields on a struct
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//! can change values and yet the struct can have the same
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//! id (because struct ids are based on the *hash* of the
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//! `#[id]` fields).
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use salsa::{Database as Db, Setter};
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use test_log::test;
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#[salsa::input]
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struct MyInput {
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field: bool,
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}
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#[derive(PartialEq, Eq, PartialOrd, Ord, Debug, Clone)]
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struct BadHash {
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field: bool,
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}
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impl From<bool> for BadHash {
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fn from(value: bool) -> Self {
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Self { field: value }
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}
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}
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impl std::hash::Hash for BadHash {
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fn hash<H: std::hash::Hasher>(&self, state: &mut H) {
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state.write_i16(0);
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}
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}
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#[salsa::tracked]
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struct MyTracked<'db> {
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#[id]
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field: BadHash,
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}
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#[salsa::tracked]
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fn the_fn(db: &dyn Db, input: MyInput) {
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let tracked0 = MyTracked::new(db, BadHash::from(input.field(db)));
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assert_eq!(tracked0.field(db).field, input.field(db));
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}
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#[test]
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fn execute() {
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let mut db = salsa::DatabaseImpl::new();
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let input = MyInput::new(&db, true);
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the_fn(&db, input);
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input.set_field(&mut db).to(false);
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the_fn(&db, input);
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}
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