1 files changed, 132 insertions, 0 deletions

diff --git a/crates/hir/src/attrs.rs b/crates/hir/src/attrs.rs
new file mode 100644
index 000000000..953960e14
--- /dev/null
+++ b/crates/hir/src/attrs.rs
@@ -0,0 +1,132 @@
+//! Attributes & documentation for hir types.
+use hir_def::{
+    attr::Attrs,
+    db::DefDatabase,
+    docs::Documentation,
+    resolver::{HasResolver, Resolver},
+    AdtId, FunctionId, GenericDefId, ModuleId, StaticId, TraitId, VariantId,
+};
+use hir_ty::db::HirDatabase;
+use stdx::impl_from;
+
+use crate::{
+    doc_links::Resolvable, Adt, Const, Enum, EnumVariant, Field, Function, GenericDef, ImplDef,
+    Local, MacroDef, Module, ModuleDef, Static, Struct, Trait, TypeAlias, TypeParam, Union,
+};
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
+pub enum AttrDef {
+    Module(Module),
+    Field(Field),
+    Adt(Adt),
+    Function(Function),
+    EnumVariant(EnumVariant),
+    Static(Static),
+    Const(Const),
+    Trait(Trait),
+    TypeAlias(TypeAlias),
+    MacroDef(MacroDef),
+}
+
+impl_from!(
+    Module,
+    Field,
+    Adt(Struct, Enum, Union),
+    EnumVariant,
+    Static,
+    Const,
+    Function,
+    Trait,
+    TypeAlias,
+    MacroDef
+    for AttrDef
+);
+
+pub trait HasAttrs {
+    fn attrs(self, db: &dyn HirDatabase) -> Attrs;
+    fn docs(self, db: &dyn HirDatabase) -> Option<Documentation>;
+}
+
+impl<T: Into<AttrDef>> HasAttrs for T {
+    fn attrs(self, db: &dyn HirDatabase) -> Attrs {
+        let def: AttrDef = self.into();
+        db.attrs(def.into())
+    }
+    fn docs(self, db: &dyn HirDatabase) -> Option<Documentation> {
+        let def: AttrDef = self.into();
+        db.documentation(def.into())
+    }
+}
+
+impl Resolvable for ModuleDef {
+    fn resolver<D: DefDatabase + HirDatabase>(&self, db: &D) -> Option<Resolver> {
+        Some(match self {
+            ModuleDef::Module(m) => ModuleId::from(m.clone()).resolver(db),
+            ModuleDef::Function(f) => FunctionId::from(f.clone()).resolver(db),
+            ModuleDef::Adt(adt) => AdtId::from(adt.clone()).resolver(db),
+            ModuleDef::EnumVariant(ev) => {
+                GenericDefId::from(GenericDef::from(ev.clone())).resolver(db)
+            }
+            ModuleDef::Const(c) => GenericDefId::from(GenericDef::from(c.clone())).resolver(db),
+            ModuleDef::Static(s) => StaticId::from(s.clone()).resolver(db),
+            ModuleDef::Trait(t) => TraitId::from(t.clone()).resolver(db),
+            ModuleDef::TypeAlias(t) => ModuleId::from(t.module(db)).resolver(db),
+            // FIXME: This should be a resolver relative to `std/core`
+            ModuleDef::BuiltinType(_t) => None?,
+        })
+    }
+
+    fn try_into_module_def(self) -> Option<ModuleDef> {
+        Some(self)
+    }
+}
+
+impl Resolvable for TypeParam {
+    fn resolver<D: DefDatabase + HirDatabase>(&self, db: &D) -> Option<Resolver> {
+        Some(ModuleId::from(self.module(db)).resolver(db))
+    }
+
+    fn try_into_module_def(self) -> Option<ModuleDef> {
+        None
+    }
+}
+
+impl Resolvable for MacroDef {
+    fn resolver<D: DefDatabase + HirDatabase>(&self, db: &D) -> Option<Resolver> {
+        Some(ModuleId::from(self.module(db)?).resolver(db))
+    }
+
+    fn try_into_module_def(self) -> Option<ModuleDef> {
+        None
+    }
+}
+
+impl Resolvable for Field {
+    fn resolver<D: DefDatabase + HirDatabase>(&self, db: &D) -> Option<Resolver> {
+        Some(VariantId::from(self.parent_def(db)).resolver(db))
+    }
+
+    fn try_into_module_def(self) -> Option<ModuleDef> {
+        None
+    }
+}
+
+impl Resolvable for ImplDef {
+    fn resolver<D: DefDatabase + HirDatabase>(&self, db: &D) -> Option<Resolver> {
+        Some(ModuleId::from(self.module(db)).resolver(db))
+    }
+
+    fn try_into_module_def(self) -> Option<ModuleDef> {
+        None
+    }
+}
+
+impl Resolvable for Local {
+    fn resolver<D: DefDatabase + HirDatabase>(&self, db: &D) -> Option<Resolver> {
+        Some(ModuleId::from(self.module(db)).resolver(db))
+    }
+
+    fn try_into_module_def(self) -> Option<ModuleDef> {
+        None
+    }
+}