5 files changed, 65 insertions, 28 deletions

diff --git a/crates/completion/src/completions.rs b/crates/completion/src/completions.rs
index 1ca5cf33d..d8dc1b1c3 100644
--- a/crates/completion/src/completions.rs
+++ b/crates/completion/src/completions.rs
@@ -20,7 +20,7 @@ use test_utils::mark;
 
 use crate::{
     item::Builder,
-    render::{EnumVariantRender, FunctionRender, MacroRender},
+    render::{ConstRender, EnumVariantRender, FunctionRender, MacroRender},
     CompletionContext, CompletionItem, CompletionItemKind, CompletionKind, CompletionScore,
     RootDatabase,
 };
@@ -194,7 +194,6 @@ impl Completions {
             Some(it) => it,
             None => return,
         };
-
         if let Some(item) = MacroRender::new(ctx.into(), name, macro_).render() {
             self.add(item);
         }
@@ -207,24 +206,13 @@ impl Completions {
         local_name: Option<String>,
     ) {
         let item = FunctionRender::new(ctx.into(), local_name, func).render();
-
         self.add(item)
     }
 
     pub(crate) fn add_const(&mut self, ctx: &CompletionContext, constant: hir::Const) {
-        let ast_node = constant.source(ctx.db).value;
-        let name = match ast_node.name() {
-            Some(name) => name,
-            _ => return,
-        };
-        let detail = const_label(&ast_node);
-
-        CompletionItem::new(CompletionKind::Reference, ctx.source_range(), name.text().to_string())
-            .kind(CompletionItemKind::Const)
-            .set_documentation(constant.docs(ctx.db))
-            .set_deprecated(is_deprecated(constant, ctx.db))
-            .detail(detail)
-            .add_to(self);
+        if let Some(item) = ConstRender::new(ctx.into(), constant).render() {
+            self.add(item);
+        }
     }
 
     pub(crate) fn add_type_alias(&mut self, ctx: &CompletionContext, type_alias: hir::TypeAlias) {
diff --git a/crates/completion/src/render.rs b/crates/completion/src/render.rs
index 66eb753b1..c614a7172 100644
--- a/crates/completion/src/render.rs
+++ b/crates/completion/src/render.rs
@@ -5,15 +5,17 @@ mod macro_;
 mod function;
 mod builder_ext;
 mod enum_variant;
+mod const_;
 
-use hir::HasAttrs;
+use hir::{Documentation, HasAttrs};
 use ide_db::RootDatabase;
 use syntax::TextRange;
 
 use crate::{config::SnippetCap, CompletionContext};
 
 pub(crate) use crate::render::{
-    enum_variant::EnumVariantRender, function::FunctionRender, macro_::MacroRender,
+    const_::ConstRender, enum_variant::EnumVariantRender, function::FunctionRender,
+    macro_::MacroRender,
 };
 
 #[derive(Debug)]
@@ -41,6 +43,10 @@ impl<'a> RenderContext<'a> {
     pub fn is_deprecated(&self, node: impl HasAttrs) -> bool {
         node.attrs(self.db()).by_key("deprecated").exists()
     }
+
+    pub fn docs(&self, node: impl HasAttrs) -> Option<Documentation> {
+        node.docs(self.db())
+    }
 }
 
 impl<'a> From<&'a CompletionContext<'a>> for RenderContext<'a> {
diff --git a/crates/completion/src/render/const_.rs b/crates/completion/src/render/const_.rs
new file mode 100644
index 000000000..d88bfa07f
--- /dev/null
+++ b/crates/completion/src/render/const_.rs
@@ -0,0 +1,47 @@
+use hir::HasSource;
+use syntax::{
+    ast::{Const, NameOwner},
+    display::const_label,
+};
+
+use crate::{
+    item::{CompletionItem, CompletionItemKind, CompletionKind},
+    render::RenderContext,
+};
+
+#[derive(Debug)]
+pub(crate) struct ConstRender<'a> {
+    ctx: RenderContext<'a>,
+    const_: hir::Const,
+    ast_node: Const,
+}
+
+impl<'a> ConstRender<'a> {
+    pub(crate) fn new(ctx: RenderContext<'a>, const_: hir::Const) -> ConstRender<'a> {
+        let ast_node = const_.source(ctx.db()).value;
+        ConstRender { ctx, const_, ast_node }
+    }
+
+    pub(crate) fn render(self) -> Option<CompletionItem> {
+        let name = self.name()?;
+        let detail = self.detail();
+
+        let item = CompletionItem::new(CompletionKind::Reference, self.ctx.source_range(), name)
+            .kind(CompletionItemKind::Const)
+            .set_documentation(self.ctx.docs(self.const_))
+            .set_deprecated(self.ctx.is_deprecated(self.const_))
+            .detail(detail)
+            .build();
+
+        Some(item)
+    }
+
+    fn name(&self) -> Option<String> {
+        let ast_node = self.const_.source(self.ctx.db()).value;
+        ast_node.name().map(|name| name.text().to_string())
+    }
+
+    fn detail(&self) -> String {
+        const_label(&self.ast_node)
+    }
+}
diff --git a/crates/completion/src/render/function.rs b/crates/completion/src/render/function.rs
index 16f15e22c..d22081236 100644
--- a/crates/completion/src/render/function.rs
+++ b/crates/completion/src/render/function.rs
@@ -1,4 +1,4 @@
-use hir::{Documentation, HasAttrs, HasSource, Type};
+use hir::{HasSource, Type};
 use syntax::{ast::Fn, display::function_declaration};
 
 use crate::{
@@ -30,7 +30,7 @@ impl<'a> FunctionRender<'a> {
         let params = self.params();
         CompletionItem::new(CompletionKind::Reference, self.ctx.source_range(), self.name.clone())
             .kind(self.kind())
-            .set_documentation(self.docs())
+            .set_documentation(self.ctx.docs(self.fn_))
             .set_deprecated(self.ctx.is_deprecated(self.fn_))
             .detail(self.detail())
             .add_call_parens(self.ctx.completion, self.name, params)
@@ -45,8 +45,8 @@ impl<'a> FunctionRender<'a> {
         if let Some(derefed_ty) = ty.remove_ref() {
             for (name, local) in self.ctx.completion.locals.iter() {
                 if name == arg && local.ty(self.ctx.db()) == derefed_ty {
-                    return (if ty.is_mutable_reference() { "&mut " } else { "&" }).to_string()
-                        + &arg.to_string();
+                    let mutability = if ty.is_mutable_reference() { "&mut " } else { "&" };
+                    return format!("{}{}", mutability, arg);
                 }
             }
         }
@@ -80,8 +80,4 @@ impl<'a> FunctionRender<'a> {
             CompletionItemKind::Function
         }
     }
-
-    fn docs(&self) -> Option<Documentation> {
-        self.fn_.docs(self.ctx.db())
-    }
 }
diff --git a/crates/completion/src/render/macro_.rs b/crates/completion/src/render/macro_.rs
index bcf94f47e..0ad8c03b3 100644
--- a/crates/completion/src/render/macro_.rs
+++ b/crates/completion/src/render/macro_.rs
@@ -1,4 +1,4 @@
-use hir::{Documentation, HasAttrs, HasSource};
+use hir::{Documentation, HasSource};
 use syntax::display::macro_label;
 use test_utils::mark;
 
@@ -23,7 +23,7 @@ impl<'a> MacroRender<'a> {
         name: String,
         macro_: hir::MacroDef,
     ) -> MacroRender<'a> {
-        let docs = macro_.docs(ctx.db());
+        let docs = ctx.docs(macro_);
         let docs_str = docs.as_ref().map_or("", |s| s.as_str());
         let (bra, ket) = guess_macro_braces(&name, docs_str);