move function rendering to presentation

crates/ra_ide_api/src/completion/complete_dot.rs

@@ -1,6 +1,6 @@
 use hir::{Ty, AdtDef};
 
-use crate::completion::{CompletionContext, Completions, CompletionItem, CompletionItemKind, CompletionKind};
+use crate::completion::{CompletionContext, Completions, CompletionKind};
 
 /// Complete dot accesses, i.e. fields or methods (currently only fields).
 pub(super) fn complete_dot(acc: &mut Completions, ctx: &CompletionContext) {
@@ -50,14 +50,7 @@ fn complete_methods(acc: &mut Completions, ctx: &CompletionContext, receiver: Ty
     receiver.iterate_methods(ctx.db, |_ty, func| {
         let sig = func.signature(ctx.db);
         if sig.has_self_param() {
-            CompletionItem::new(
-                CompletionKind::Reference,
-                ctx.source_range(),
-                sig.name().to_string(),
-            )
-            .from_function(ctx, func)
-            .kind(CompletionItemKind::Method)
-            .add_to(acc);
+            acc.add_function(CompletionKind::Reference, ctx, func);
         }
         None::<()>
     });

crates/ra_ide_api/src/completion/complete_path.rs

@@ -64,14 +64,7 @@ pub(super) fn complete_path(acc: &mut Completions, ctx: &CompletionContext) {
                 hir::ImplItem::Method(func) => {
                     let sig = func.signature(ctx.db);
                     if !sig.has_self_param() {
-                        CompletionItem::new(
-                            CompletionKind::Reference,
-                            ctx.source_range(),
-                            sig.name().to_string(),
-                        )
-                        .from_function(ctx, func)
-                        .kind(CompletionItemKind::Method)
-                        .add_to(acc);
+                        acc.add_function(CompletionKind::Reference, ctx, func);
                     }
                     None::<()>
                 }

crates/ra_ide_api/src/completion/presentation.rs

@@ -1,7 +1,11 @@
 //! This modules takes care of rendering various defenitions as completion items.
+use test_utils::tested_by;
 use hir::Docs;
 
-use crate::completion::{Completions, CompletionKind, CompletionItemKind, CompletionContext, CompletionItem};
+use crate::completion::{
+    Completions, CompletionKind, CompletionItemKind, CompletionContext, CompletionItem,
+    function_label,
+};
 
 impl Completions {
     pub(crate) fn add_field(
@@ -30,4 +34,39 @@ impl Completions {
             .detail(ty.to_string())
             .add_to(self);
     }
+
+    pub(crate) fn add_function(
+        &mut self,
+        kind: CompletionKind,
+        ctx: &CompletionContext,
+        func: hir::Function,
+    ) {
+        let sig = func.signature(ctx.db);
+
+        let mut builder = CompletionItem::new(kind, ctx.source_range(), sig.name().to_string())
+            .kind(if sig.has_self_param() {
+                CompletionItemKind::Method
+            } else {
+                CompletionItemKind::Function
+            })
+            .set_documentation(func.docs(ctx.db))
+            .set_detail(function_item_label(ctx, func));
+        // If not an import, add parenthesis automatically.
+        if ctx.use_item_syntax.is_none() && !ctx.is_call {
+            tested_by!(inserts_parens_for_function_calls);
+            let snippet =
+                if sig.params().is_empty() || sig.has_self_param() && sig.params().len() == 1 {
+                    format!("{}()$0", sig.name())
+                } else {
+                    format!("{}($0)", sig.name())
+                };
+            builder = builder.insert_snippet(snippet);
+        }
+        self.add(builder)
+    }
+}
+
+fn function_item_label(ctx: &CompletionContext, function: hir::Function) -> Option<String> {
+    let node = function.source(ctx.db).1;
+    function_label(&node)
 }

crates/ra_ide_api/src/completion/snapshots/completion_item__dont_render_function_parens_if_already_call_assoc_fn.snap

@@ -1,6 +1,6 @@
 ---
-created: "2019-02-18T09:22:24.268227065Z"
-creator: insta@0.6.2
+created: "2019-02-24T16:33:48.008220694Z"
+creator: insta@0.6.3
 source: crates/ra_ide_api/src/completion/completion_item.rs
 expression: kind_completions
 ---
@@ -10,7 +10,7 @@ expression: kind_completions
         source_range: [67; 69),
         delete: [67; 69),
         insert: "new",
-        kind: Method,
+        kind: Function,
         detail: "fn new() -> Foo"
     }
 ]

crates/ra_ide_api/src/completion/snapshots/completion_item__struct_associated_method.snap

@@ -1,6 +1,6 @@
 ---
-created: "2019-02-18T09:22:24.093082839Z"
-creator: insta@0.6.2
+created: "2019-02-24T16:33:47.990111169Z"
+creator: insta@0.6.3
 source: crates/ra_ide_api/src/completion/completion_item.rs
 expression: kind_completions
 ---
@@ -10,7 +10,7 @@ expression: kind_completions
         source_range: [100; 100),
         delete: [100; 100),
         insert: "m()$0",
-        kind: Method,
+        kind: Function,
         detail: "fn m()",
         documentation: Documentation(
             "An associated method"