From bcff61257a678b54721aceab5aec7a9f6cce8d9c Mon Sep 17 00:00:00 2001
From: Aleksey Kladov <aleksey.kladov@gmail.com>
Date: Wed, 19 Jun 2019 23:46:50 +0300
Subject: Add firewall query to lang items

With an intermediate query, changing one module won't cause reparsing
of all modules
---
 crates/ra_hir/src/code_model.rs |  2 +-
 crates/ra_hir/src/db.rs         |  3 +++
 crates/ra_hir/src/lang_item.rs  | 50 ++++++++++++++++++++++++++++-------------
 3 files changed, 38 insertions(+), 17 deletions(-)

diff --git a/crates/ra_hir/src/code_model.rs b/crates/ra_hir/src/code_model.rs
index 10f975b31..ebbc37c0e 100644
--- a/crates/ra_hir/src/code_model.rs
+++ b/crates/ra_hir/src/code_model.rs
@@ -282,7 +282,7 @@ impl Module {
             .collect()
     }
 
-    pub fn impl_blocks(self, db: &impl HirDatabase) -> Vec<ImplBlock> {
+    pub fn impl_blocks(self, db: &impl DefDatabase) -> Vec<ImplBlock> {
         let module_impl_blocks = db.impls_in_module(self);
         module_impl_blocks
             .impls
diff --git a/crates/ra_hir/src/db.rs b/crates/ra_hir/src/db.rs
index 23c36014b..d8832a9de 100644
--- a/crates/ra_hir/src/db.rs
+++ b/crates/ra_hir/src/db.rs
@@ -121,6 +121,9 @@ pub trait DefDatabase: SourceDatabase {
     #[salsa::invoke(crate::ConstData::static_data_query)]
     fn static_data(&self, konst: Static) -> Arc<ConstData>;
 
+    #[salsa::invoke(crate::lang_item::LangItems::module_lang_items_query)]
+    fn module_lang_items(&self, module: Module) -> Option<Arc<LangItems>>;
+
     #[salsa::invoke(crate::lang_item::LangItems::lang_items_query)]
     fn lang_items(&self, krate: Crate) -> Arc<LangItems>;
 
diff --git a/crates/ra_hir/src/lang_item.rs b/crates/ra_hir/src/lang_item.rs
index 18ac0fcf9..48b60f2dd 100644
--- a/crates/ra_hir/src/lang_item.rs
+++ b/crates/ra_hir/src/lang_item.rs
@@ -31,7 +31,7 @@ impl LangItemTarget {
     }
 }
 
-#[derive(Debug, Clone, PartialEq, Eq)]
+#[derive(Default, Debug, Clone, PartialEq, Eq)]
 pub struct LangItems {
     items: FxHashMap<SmolStr, LangItemTarget>,
 }
@@ -46,15 +46,28 @@ impl LangItems {
         db: &(impl DefDatabase + AstDatabase),
         krate: Crate,
     ) -> Arc<LangItems> {
-        let mut lang_items = LangItems { items: FxHashMap::default() };
+        let mut lang_items = LangItems::default();
 
         if let Some(module) = krate.root_module(db) {
-            lang_items.collect_lang_items_recursive(db, &module);
+            lang_items.collect_lang_items_recursive(db, module);
         }
 
         Arc::new(lang_items)
     }
 
+    pub(crate) fn module_lang_items_query(
+        db: &(impl DefDatabase + AstDatabase),
+        module: Module,
+    ) -> Option<Arc<LangItems>> {
+        let mut lang_items = LangItems::default();
+        lang_items.collect_lang_items(db, module);
+        if lang_items.items.is_empty() {
+            None
+        } else {
+            Some(Arc::new(lang_items))
+        }
+    }
+
     /// Salsa query. Look for a lang item, starting from the specified crate and recursively
     /// traversing its dependencies.
     pub(crate) fn lang_item_query(
@@ -78,19 +91,14 @@ impl LangItems {
         }
     }
 
-    fn collect_lang_items_recursive(
-        &mut self,
-        db: &(impl DefDatabase + AstDatabase),
-        module: &Module,
-    ) {
+    fn collect_lang_items(&mut self, db: &(impl DefDatabase + AstDatabase), module: Module) {
         // Look for impl targets
-        let (impl_blocks, source_map) = db.impls_in_module_with_source_map(module.clone());
-        let source = module.definition_source(db).ast;
-        for (impl_id, _) in impl_blocks.impls.iter() {
-            let impl_block = source_map.get(&source, impl_id);
-            if let Some(lang_item_name) = lang_item_name(&*impl_block) {
-                let imp = ImplBlock::from_id(*module, impl_id);
-                self.items.entry(lang_item_name).or_insert_with(|| LangItemTarget::ImplBlock(imp));
+        for impl_block in module.impl_blocks(db) {
+            let src = impl_block.source(db);
+            if let Some(lang_item_name) = lang_item_name(&*src.ast) {
+                self.items
+                    .entry(lang_item_name)
+                    .or_insert_with(|| LangItemTarget::ImplBlock(impl_block));
             }
         }
 
@@ -106,10 +114,20 @@ impl LangItems {
                 _ => {}
             }
         }
+    }
+
+    fn collect_lang_items_recursive(
+        &mut self,
+        db: &(impl DefDatabase + AstDatabase),
+        module: Module,
+    ) {
+        if let Some(module_lang_items) = db.module_lang_items(module) {
+            self.items.extend(module_lang_items.items.iter().map(|(k, v)| (k.clone(), v.clone())))
+        }
 
         // Look for lang items in the children
         for child in module.children(db) {
-            self.collect_lang_items_recursive(db, &child);
+            self.collect_lang_items_recursive(db, child);
         }
     }
 
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