3 files changed, 51 insertions, 39 deletions

diff --git a/crates/ra_hir/src/code_model_api.rs b/crates/ra_hir/src/code_model_api.rs
index e16013956..1fa591ea4 100644
--- a/crates/ra_hir/src/code_model_api.rs
+++ b/crates/ra_hir/src/code_model_api.rs
@@ -16,7 +16,7 @@ use crate::{
     code_model_impl::def_id_to_ast,
     docs::{Documentation, Docs, docs_from_ast},
     module_tree::ModuleId,
-    ids::{FunctionId, StructId, EnumId, EnumVariantId},
+    ids::{FunctionId, StructId, EnumId, EnumVariantId, AstItemDef},
 };
 
 /// hir::Crate describes a single crate. It's the main interface with which
@@ -197,8 +197,12 @@ pub struct Struct {
 }
 
 impl Struct {
+    pub fn source(&self, db: &impl HirDatabase) -> (HirFileId, TreeArc<ast::StructDef>) {
+        self.id.source(db)
+    }
+
     pub fn module(&self, db: &impl HirDatabase) -> Module {
-        self.id.loc(db).module
+        self.id.module(db)
     }
 
     pub fn name(&self, db: &impl HirDatabase) -> Option<Name> {
@@ -217,10 +221,6 @@ impl Struct {
             .collect()
     }
 
-    pub fn source(&self, db: &impl HirDatabase) -> (HirFileId, TreeArc<ast::StructDef>) {
-        self.id.loc(db).source(db)
-    }
-
     pub fn generic_params(&self, db: &impl HirDatabase) -> Arc<GenericParams> {
         db.generic_params((*self).into())
     }
@@ -238,8 +238,12 @@ pub struct Enum {
 }
 
 impl Enum {
+    pub fn source(&self, db: &impl HirDatabase) -> (HirFileId, TreeArc<ast::EnumDef>) {
+        self.id.source(db)
+    }
+
     pub fn module(&self, db: &impl HirDatabase) -> Module {
-        self.id.loc(db).module
+        self.id.module(db)
     }
 
     pub fn name(&self, db: &impl HirDatabase) -> Option<Name> {
@@ -250,10 +254,6 @@ impl Enum {
         db.enum_data(*self).variants.clone()
     }
 
-    pub fn source(&self, db: &impl HirDatabase) -> (HirFileId, TreeArc<ast::EnumDef>) {
-        self.id.loc(db).source(db)
-    }
-
     pub fn generic_params(&self, db: &impl HirDatabase) -> Arc<GenericParams> {
         db.generic_params((*self).into())
     }
@@ -271,8 +271,11 @@ pub struct EnumVariant {
 }
 
 impl EnumVariant {
+    pub fn source(&self, db: &impl HirDatabase) -> (HirFileId, TreeArc<ast::EnumVariant>) {
+        self.id.source(db)
+    }
     pub fn module(&self, db: &impl HirDatabase) -> Module {
-        self.id.loc(db).module
+        self.id.module(db)
     }
     pub fn parent_enum(&self, db: &impl HirDatabase) -> Enum {
         db.enum_variant_data(*self).parent_enum.clone()
@@ -296,10 +299,6 @@ impl EnumVariant {
             })
             .collect()
     }
-
-    pub fn source(&self, db: &impl HirDatabase) -> (HirFileId, TreeArc<ast::EnumVariant>) {
-        self.id.loc(db).source(db)
-    }
 }
 
 impl Docs for EnumVariant {
@@ -348,7 +347,11 @@ impl FnSignature {
 
 impl Function {
     pub fn source(&self, db: &impl HirDatabase) -> (HirFileId, TreeArc<ast::FnDef>) {
-        self.id.loc(db).source(db)
+        self.id.source(db)
+    }
+
+    pub fn module(&self, db: &impl HirDatabase) -> Module {
+        self.id.module(db)
     }
 
     pub fn body_syntax_mapping(&self, db: &impl HirDatabase) -> Arc<BodySyntaxMapping> {
diff --git a/crates/ra_hir/src/code_model_impl/function.rs b/crates/ra_hir/src/code_model_impl/function.rs
index 8a2ab5714..6ce5c77b1 100644
--- a/crates/ra_hir/src/code_model_impl/function.rs
+++ b/crates/ra_hir/src/code_model_impl/function.rs
@@ -30,10 +30,6 @@ impl Function {
         db.body_hir(*self)
     }
 
-    pub(crate) fn module(&self, db: &impl HirDatabase) -> Module {
-        self.id.loc(db).module
-    }
-
     /// The containing impl block, if this is a method.
     pub(crate) fn impl_block(&self, db: &impl HirDatabase) -> Option<ImplBlock> {
         let module_impls = db.impls_in_module(self.module(db));
diff --git a/crates/ra_hir/src/ids.rs b/crates/ra_hir/src/ids.rs
index 7ed5dbec7..262047849 100644
--- a/crates/ra_hir/src/ids.rs
+++ b/crates/ra_hir/src/ids.rs
@@ -1,8 +1,11 @@
-use std::marker::PhantomData;
+use std::{
+    marker::PhantomData,
+    hash::Hash,
+};
 
 use ra_db::{LocationIntener, FileId};
 use ra_syntax::{TreeArc, SyntaxNode, SourceFile, AstNode, ast};
-use ra_arena::{Arena, RawId, impl_arena_id};
+use ra_arena::{Arena, RawId, ArenaId, impl_arena_id};
 
 use crate::{
     HirDatabase, Def,
@@ -179,43 +182,53 @@ impl<N: AstNode> Clone for ItemLoc<N> {
     }
 }
 
+pub(crate) trait AstItemDef<N: AstNode + Eq + Hash>: ArenaId + Clone {
+    fn interner(interner: &HirInterner) -> &LocationIntener<ItemLoc<N>, Self>;
+    fn source(self, db: &impl HirDatabase) -> (HirFileId, TreeArc<N>) {
+        let int = Self::interner(db.as_ref());
+        let loc = int.id2loc(self);
+        loc.source(db)
+    }
+    fn module(self, db: &impl HirDatabase) -> Module {
+        let int = Self::interner(db.as_ref());
+        let loc = int.id2loc(self);
+        loc.module
+    }
+}
+
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub struct FunctionId(RawId);
 impl_arena_id!(FunctionId);
-
-impl FunctionId {
-    pub(crate) fn loc(self, db: &impl AsRef<HirInterner>) -> ItemLoc<ast::FnDef> {
-        db.as_ref().fns.id2loc(self)
+impl AstItemDef<ast::FnDef> for FunctionId {
+    fn interner(interner: &HirInterner) -> &LocationIntener<ItemLoc<ast::FnDef>, Self> {
+        &interner.fns
     }
 }
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub struct StructId(RawId);
 impl_arena_id!(StructId);
-
-impl StructId {
-    pub(crate) fn loc(self, db: &impl AsRef<HirInterner>) -> ItemLoc<ast::StructDef> {
-        db.as_ref().structs.id2loc(self)
+impl AstItemDef<ast::StructDef> for StructId {
+    fn interner(interner: &HirInterner) -> &LocationIntener<ItemLoc<ast::StructDef>, Self> {
+        &interner.structs
     }
 }
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub struct EnumId(RawId);
 impl_arena_id!(EnumId);
-
-impl EnumId {
-    pub(crate) fn loc(self, db: &impl AsRef<HirInterner>) -> ItemLoc<ast::EnumDef> {
-        db.as_ref().enums.id2loc(self)
+impl AstItemDef<ast::EnumDef> for EnumId {
+    fn interner(interner: &HirInterner) -> &LocationIntener<ItemLoc<ast::EnumDef>, Self> {
+        &interner.enums
     }
 }
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub struct EnumVariantId(RawId);
 impl_arena_id!(EnumVariantId);
-
-impl EnumVariantId {
-    pub(crate) fn loc(self, db: &impl AsRef<HirInterner>) -> ItemLoc<ast::EnumVariant> {
-        db.as_ref().enum_variants.id2loc(self)
+impl AstItemDef<ast::EnumVariant> for EnumVariantId {
+    fn interner(interner: &HirInterner) -> &LocationIntener<ItemLoc<ast::EnumVariant>, Self> {
+        &interner.enum_variants
     }
 }