3 files changed, 54 insertions, 21 deletions

diff --git a/crates/ra_analysis/src/completion.rs b/crates/ra_analysis/src/completion.rs
index f480af611..ed1b6dd0c 100644
--- a/crates/ra_analysis/src/completion.rs
+++ b/crates/ra_analysis/src/completion.rs
@@ -1,3 +1,4 @@
+mod completion_item;
 mod reference_completion;
 
 use ra_editor::find_node_at_offset;
@@ -17,15 +18,7 @@ use crate::{
     Cancelable, FilePosition
 };
 
-#[derive(Debug)]
-pub struct CompletionItem {
-    /// What user sees in pop-up
-    pub label: String,
-    /// What string is used for filtering, defaults to label
-    pub lookup: Option<String>,
-    /// What is inserted, defaults to label
-    pub snippet: Option<String>,
-}
+pub use crate::completion::completion_item::CompletionItem;
 
 pub(crate) fn completions(
     db: &db::RootDatabase,
@@ -63,6 +56,10 @@ pub(crate) fn completions(
     Ok(res)
 }
 
+/// Complete repeated parametes, both name and type. For example, if all
+/// functions in a file have a `spam: &mut Spam` parameter, a completion with
+/// `spam: &mut Spam` insert text/label and `spam` lookup string will be
+/// suggested.
 fn param_completions(ctx: SyntaxNodeRef, acc: &mut Vec<CompletionItem>) {
     let mut params = FxHashMap::default();
     for node in ctx.ancestors() {
@@ -81,13 +78,7 @@ fn param_completions(ctx: SyntaxNodeRef, acc: &mut Vec<CompletionItem>) {
                 Some((label, lookup))
             }
         })
-        .for_each(|(label, lookup)| {
-            acc.push(CompletionItem {
-                label,
-                lookup: Some(lookup),
-                snippet: None,
-            })
-        });
+        .for_each(|(label, lookup)| CompletionItem::new(label).lookup_by(lookup).add_to(acc));
 
     fn process<'a, N: ast::FnDefOwner<'a>>(
         node: N,
diff --git a/crates/ra_analysis/src/completion/completion_item.rs b/crates/ra_analysis/src/completion/completion_item.rs
new file mode 100644
index 000000000..309b0108d
--- /dev/null
+++ b/crates/ra_analysis/src/completion/completion_item.rs
@@ -0,0 +1,44 @@
+#[derive(Debug)]
+pub struct CompletionItem {
+    /// What user sees in pop-up in the UI.
+    pub label: String,
+    /// What string is used for filtering, defaults to label.
+    pub lookup: Option<String>,
+    /// What is inserted, defaults to label.
+    pub snippet: Option<String>,
+}
+
+impl CompletionItem {
+    pub(crate) fn new(label: impl Into<String>) -> Builder {
+        let label = label.into();
+        Builder {
+            label,
+            lookup: None,
+            snippet: None,
+        }
+    }
+}
+
+pub(crate) struct Builder {
+    label: String,
+    lookup: Option<String>,
+    snippet: Option<String>,
+}
+
+impl Builder {
+    pub fn add_to(self, acc: &mut Vec<CompletionItem>) {
+        acc.push(self.build())
+    }
+
+    pub fn build(self) -> CompletionItem {
+        CompletionItem {
+            label: self.label,
+            lookup: self.lookup,
+            snippet: self.snippet,
+        }
+    }
+    pub fn lookup_by(mut self, lookup: impl Into<String>) -> Builder {
+        self.lookup = Some(lookup.into());
+        self
+    }
+}
diff --git a/crates/ra_analysis/src/completion/reference_completion.rs b/crates/ra_analysis/src/completion/reference_completion.rs
index f483ed045..457ca13cc 100644
--- a/crates/ra_analysis/src/completion/reference_completion.rs
+++ b/crates/ra_analysis/src/completion/reference_completion.rs
@@ -6,11 +6,9 @@ use ra_syntax::{
     ast::{self, LoopBodyOwner},
     SyntaxKind::*,
 };
-use     hir::{
-        self,
-        FnScopes,
-        Def,
-        Path,
+use hir::{
+    self,
+    FnScopes, Def, Path
 };
 
 use crate::{