From f08109bd2d2fdfe52b0443d5db2f33934aeca5c3 Mon Sep 17 00:00:00 2001
From: Daniel Frampton <Daniel.Frampton@microsoft.com>
Date: Mon, 4 Jan 2021 12:56:21 -0800
Subject: Introduce new queries to compute   1) the set of attributes for all
 variants of an enum, and   2) the set of attributes for all fields of a
 variant.

This avoids the current n^2 behavior when rendering completion for variants, which
prevents completion for enums with large numbers of variants.
---
 crates/hir_def/src/attr.rs | 56 +++++++++++++++++++++++++++++++++++++---------
 1 file changed, 46 insertions(+), 10 deletions(-)

(limited to 'crates/hir_def/src/attr.rs')

diff --git a/crates/hir_def/src/attr.rs b/crates/hir_def/src/attr.rs
index 6b79e7bad..9e6426b31 100644
--- a/crates/hir_def/src/attr.rs
+++ b/crates/hir_def/src/attr.rs
@@ -2,6 +2,7 @@
 
 use std::{ops, sync::Arc};
 
+use arena::map::ArenaMap;
 use base_db::CrateId;
 use cfg::{CfgExpr, CfgOptions};
 use either::Either;
@@ -21,7 +22,8 @@ use crate::{
     nameres::ModuleSource,
     path::{ModPath, PathKind},
     src::HasChildSource,
-    AdtId, AttrDefId, GenericParamId, Lookup,
+    AdtId, AttrDefId, EnumId, GenericParamId, HasModule, LocalEnumVariantId, LocalFieldId, Lookup,
+    VariantId,
 };
 
 /// Holds documentation
@@ -210,16 +212,10 @@ impl Attrs {
                 }
             }
             AttrDefId::FieldId(it) => {
-                let src = it.parent.child_source(db);
-                match &src.value[it.local_id] {
-                    Either::Left(_tuple) => RawAttrs::default(),
-                    Either::Right(record) => RawAttrs::from_attrs_owner(db, src.with_value(record)),
-                }
+                return db.fields_attrs(it.parent)[it.local_id].clone();
             }
-            AttrDefId::EnumVariantId(var_id) => {
-                let src = var_id.parent.child_source(db);
-                let src = src.as_ref().map(|it| &it[var_id.local_id]);
-                RawAttrs::from_attrs_owner(db, src.map(|it| it as &dyn AttrsOwner))
+            AttrDefId::EnumVariantId(it) => {
+                return db.variants_attrs(it.parent)[it.local_id].clone();
             }
             AttrDefId::AdtId(it) => match it {
                 AdtId::StructId(it) => attrs_from_item_tree(it.lookup(db).id, db),
@@ -259,6 +255,46 @@ impl Attrs {
         raw_attrs.filter(db, def.krate(db))
     }
 
+    pub(crate) fn variants_attrs_query(
+        db: &dyn DefDatabase,
+        e: EnumId,
+    ) -> Arc<ArenaMap<LocalEnumVariantId, Attrs>> {
+        let krate = e.lookup(db).container.module(db).krate;
+        let src = e.child_source(db);
+        let mut res = ArenaMap::default();
+
+        for (id, var) in src.value.iter() {
+            let attrs = RawAttrs::from_attrs_owner(db, src.with_value(var as &dyn AttrsOwner))
+                .filter(db, krate);
+
+            res.insert(id, attrs)
+        }
+
+        Arc::new(res)
+    }
+
+    pub(crate) fn fields_attrs_query(
+        db: &dyn DefDatabase,
+        v: VariantId,
+    ) -> Arc<ArenaMap<LocalFieldId, Attrs>> {
+        let krate = v.module(db).krate;
+        let src = v.child_source(db);
+        let mut res = ArenaMap::default();
+
+        for (id, fld) in src.value.iter() {
+            let attrs = match fld {
+                Either::Left(_tuple) => Attrs::default(),
+                Either::Right(record) => {
+                    RawAttrs::from_attrs_owner(db, src.with_value(record)).filter(db, krate)
+                }
+            };
+
+            res.insert(id, attrs);
+        }
+
+        Arc::new(res)
+    }
+
     pub fn by_key(&self, key: &'static str) -> AttrQuery<'_> {
         AttrQuery { attrs: self, key }
     }
-- 
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