rust/crates/hir_ty/src/tls.rs
2021-12-07 17:31:26 +01:00

134 lines
4.7 KiB
Rust

//! Implementation of Chalk debug helper functions using TLS.
use std::fmt;
use itertools::Itertools;
use crate::{
chalk_db, db::HirDatabase, from_assoc_type_id, from_chalk_trait_id, mapping::from_chalk,
CallableDefId, Interner,
};
use hir_def::{AdtId, ItemContainerId, Lookup, TypeAliasId};
pub(crate) use unsafe_tls::{set_current_program, with_current_program};
pub(crate) struct DebugContext<'a>(&'a dyn HirDatabase);
impl DebugContext<'_> {
pub(crate) fn debug_struct_id(
&self,
id: chalk_db::AdtId,
f: &mut fmt::Formatter<'_>,
) -> Result<(), fmt::Error> {
let name = match id.0 {
AdtId::StructId(it) => self.0.struct_data(it).name.clone(),
AdtId::UnionId(it) => self.0.union_data(it).name.clone(),
AdtId::EnumId(it) => self.0.enum_data(it).name.clone(),
};
write!(f, "{}", name)
}
pub(crate) fn debug_trait_id(
&self,
id: chalk_db::TraitId,
fmt: &mut fmt::Formatter<'_>,
) -> Result<(), fmt::Error> {
let trait_: hir_def::TraitId = from_chalk_trait_id(id);
let trait_data = self.0.trait_data(trait_);
write!(fmt, "{}", trait_data.name)
}
pub(crate) fn debug_assoc_type_id(
&self,
id: chalk_db::AssocTypeId,
fmt: &mut fmt::Formatter<'_>,
) -> Result<(), fmt::Error> {
let type_alias: TypeAliasId = from_assoc_type_id(id);
let type_alias_data = self.0.type_alias_data(type_alias);
let trait_ = match type_alias.lookup(self.0.upcast()).container {
ItemContainerId::TraitId(t) => t,
_ => panic!("associated type not in trait"),
};
let trait_data = self.0.trait_data(trait_);
write!(fmt, "{}::{}", trait_data.name, type_alias_data.name)
}
pub(crate) fn debug_projection_ty(
&self,
projection_ty: &chalk_ir::ProjectionTy<Interner>,
fmt: &mut fmt::Formatter<'_>,
) -> Result<(), fmt::Error> {
let type_alias = from_assoc_type_id(projection_ty.associated_ty_id);
let type_alias_data = self.0.type_alias_data(type_alias);
let trait_ = match type_alias.lookup(self.0.upcast()).container {
ItemContainerId::TraitId(t) => t,
_ => panic!("associated type not in trait"),
};
let trait_data = self.0.trait_data(trait_);
let params = projection_ty.substitution.as_slice(&Interner);
write!(fmt, "<{:?} as {}", &params[0], trait_data.name,)?;
if params.len() > 1 {
write!(
fmt,
"<{}>",
&params[1..].iter().format_with(", ", |x, f| f(&format_args!("{:?}", x))),
)?;
}
write!(fmt, ">::{}", type_alias_data.name)
}
pub(crate) fn debug_fn_def_id(
&self,
fn_def_id: chalk_ir::FnDefId<Interner>,
fmt: &mut fmt::Formatter<'_>,
) -> Result<(), fmt::Error> {
let def: CallableDefId = from_chalk(self.0, fn_def_id);
let name = match def {
CallableDefId::FunctionId(ff) => self.0.function_data(ff).name.clone(),
CallableDefId::StructId(s) => self.0.struct_data(s).name.clone(),
CallableDefId::EnumVariantId(e) => {
let enum_data = self.0.enum_data(e.parent);
enum_data.variants[e.local_id].name.clone()
}
};
match def {
CallableDefId::FunctionId(_) => write!(fmt, "{{fn {}}}", name),
CallableDefId::StructId(_) | CallableDefId::EnumVariantId(_) => {
write!(fmt, "{{ctor {}}}", name)
}
}
}
}
mod unsafe_tls {
use super::DebugContext;
use crate::db::HirDatabase;
use scoped_tls::scoped_thread_local;
scoped_thread_local!(static PROGRAM: DebugContext);
pub(crate) fn with_current_program<R>(
op: impl for<'a> FnOnce(Option<&'a DebugContext<'a>>) -> R,
) -> R {
if PROGRAM.is_set() {
PROGRAM.with(|prog| op(Some(prog)))
} else {
op(None)
}
}
pub(crate) fn set_current_program<OP, R>(p: &dyn HirDatabase, op: OP) -> R
where
OP: FnOnce() -> R,
{
let ctx = DebugContext(p);
// we're transmuting the lifetime in the DebugContext to static. This is
// fine because we only keep the reference for the lifetime of this
// function, *and* the only way to access the context is through
// `with_current_program`, which hides the lifetime through the `for`
// type.
let static_p: &DebugContext<'static> =
unsafe { std::mem::transmute::<&DebugContext, &DebugContext<'static>>(&ctx) };
PROGRAM.set(static_p, || op())
}
}