3 files changed, 127 insertions, 44 deletions

diff --git a/crates/ra_analysis/src/completion.rs b/crates/ra_analysis/src/completion.rs
index 883b3e851..d91304bc2 100644
--- a/crates/ra_analysis/src/completion.rs
+++ b/crates/ra_analysis/src/completion.rs
@@ -4,13 +4,12 @@ mod reference_completion;
 mod complete_fn_param;
 mod complete_keyword;
 mod complete_snippet;
+mod complete_path;
 
 use ra_editor::find_node_at_offset;
 use ra_text_edit::AtomTextEdit;
 use ra_syntax::{
-    algo::{
-        find_leaf_at_offset,
-    },
+    algo::find_leaf_at_offset,
     ast,
     AstNode,
     SyntaxNodeRef,
@@ -48,11 +47,12 @@ pub(crate) fn completions(
         reference_completion::completions(&mut acc, db, &module, &file, name_ref)?;
     }
 
-    let ctx = ctry!(SyntaxContext::new(&original_file, position.offset));
+    let ctx = ctry!(SyntaxContext::new(db, &original_file, position)?);
     complete_fn_param::complete_fn_param(&mut acc, &ctx);
     complete_keyword::complete_expr_keyword(&mut acc, &ctx);
     complete_snippet::complete_expr_snippet(&mut acc, &ctx);
     complete_snippet::complete_item_snippet(&mut acc, &ctx);
+    complete_path::complete_path(&mut acc, &ctx)?;
 
     Ok(Some(acc))
 }
@@ -61,31 +61,44 @@ pub(crate) fn completions(
 /// exactly is the cursor, syntax-wise.
 #[derive(Debug)]
 pub(super) struct SyntaxContext<'a> {
+    db: &'a db::RootDatabase,
     leaf: SyntaxNodeRef<'a>,
+    module: Option<hir::Module>,
     enclosing_fn: Option<ast::FnDef<'a>>,
     is_param: bool,
     /// A single-indent path, like `foo`.
     is_trivial_path: bool,
+    /// If not a trivial, path, the prefix (qualifier).
+    path_prefix: Option<hir::Path>,
     after_if: bool,
     is_stmt: bool,
     /// Something is typed at the "top" level, in module or impl/trait.
     is_new_item: bool,
 }
 
-impl SyntaxContext<'_> {
-    pub(super) fn new(original_file: &SourceFileNode, offset: TextUnit) -> Option<SyntaxContext> {
-        let leaf = find_leaf_at_offset(original_file.syntax(), offset).left_biased()?;
+impl<'a> SyntaxContext<'a> {
+    pub(super) fn new(
+        db: &'a db::RootDatabase,
+        original_file: &'a SourceFileNode,
+        position: FilePosition,
+    ) -> Cancelable<Option<SyntaxContext<'a>>> {
+        let module = source_binder::module_from_position(db, position)?;
+        let leaf =
+            ctry!(find_leaf_at_offset(original_file.syntax(), position.offset).left_biased());
         let mut ctx = SyntaxContext {
+            db,
             leaf,
+            module,
             enclosing_fn: None,
             is_param: false,
             is_trivial_path: false,
+            path_prefix: None,
             after_if: false,
             is_stmt: false,
             is_new_item: false,
         };
-        ctx.fill(original_file, offset);
-        Some(ctx)
+        ctx.fill(original_file, position.offset);
+        Ok(Some(ctx))
     }
 
     fn fill(&mut self, original_file: &SourceFileNode, offset: TextUnit) {
@@ -140,11 +153,13 @@ impl SyntaxContext<'_> {
         };
         if let Some(segment) = ast::PathSegment::cast(parent) {
             let path = segment.parent_path();
-            // if let Some(path) = Path::from_ast(path) {
-            //     if !path.is_ident() {
-            //         return Some(NameRefKind::Path(path));
-            //     }
-            // }
+            if let Some(mut path) = hir::Path::from_ast(path) {
+                if !path.is_ident() {
+                    path.segments.pop().unwrap();
+                    self.path_prefix = Some(path);
+                    return;
+                }
+            }
             if path.qualifier().is_none() {
                 self.is_trivial_path = true;
                 self.enclosing_fn = self
diff --git a/crates/ra_analysis/src/completion/complete_path.rs b/crates/ra_analysis/src/completion/complete_path.rs
new file mode 100644
index 000000000..d04503e46
--- /dev/null
+++ b/crates/ra_analysis/src/completion/complete_path.rs
@@ -0,0 +1,95 @@
+use crate::{
+    completion::{CompletionItem, Completions, CompletionKind::*, SyntaxContext},
+    Cancelable,
+};
+
+pub(super) fn complete_path(acc: &mut Completions, ctx: &SyntaxContext) -> Cancelable<()> {
+    let (path, module) = match (&ctx.path_prefix, &ctx.module) {
+        (Some(path), Some(module)) => (path.clone(), module),
+        _ => return Ok(()),
+    };
+    let def_id = match module.resolve_path(ctx.db, path)? {
+        None => return Ok(()),
+        Some(it) => it,
+    };
+    let target_module = match def_id.resolve(ctx.db)? {
+        hir::Def::Module(it) => it,
+        _ => return Ok(()),
+    };
+    let module_scope = target_module.scope(ctx.db)?;
+    module_scope.entries().for_each(|(name, _res)| {
+        CompletionItem::new(name.to_string())
+            .kind(Reference)
+            .add_to(acc)
+    });
+    Ok(())
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::completion::{CompletionKind, check_completion};
+
+    fn check_reference_completion(code: &str, expected_completions: &str) {
+        check_completion(code, expected_completions, CompletionKind::Reference);
+    }
+
+    #[test]
+    fn completes_use_item_starting_with_self() {
+        check_reference_completion(
+            r"
+            use self::m::<|>;
+
+            mod m {
+                struct Bar;
+            }
+            ",
+            "Bar",
+        );
+    }
+
+    #[test]
+    fn completes_use_item_starting_with_crate() {
+        check_reference_completion(
+            "
+            //- /lib.rs
+            mod foo;
+            struct Spam;
+            //- /foo.rs
+            use crate::Sp<|>
+            ",
+            "Spam;foo",
+        );
+    }
+
+    #[test]
+    fn completes_nested_use_tree() {
+        check_reference_completion(
+            "
+            //- /lib.rs
+            mod foo;
+            struct Spam;
+            //- /foo.rs
+            use crate::{Sp<|>};
+            ",
+            "Spam;foo",
+        );
+    }
+
+    #[test]
+    fn completes_deeply_nested_use_tree() {
+        check_reference_completion(
+            "
+            //- /lib.rs
+            mod foo;
+            pub mod bar {
+                pub mod baz {
+                    pub struct Spam;
+                }
+            }
+            //- /foo.rs
+            use crate::{bar::{baz::Sp<|>}};
+            ",
+            "Spam",
+        );
+    }
+}
diff --git a/crates/ra_analysis/src/completion/reference_completion.rs b/crates/ra_analysis/src/completion/reference_completion.rs
index 46d381927..459ed8f6f 100644
--- a/crates/ra_analysis/src/completion/reference_completion.rs
+++ b/crates/ra_analysis/src/completion/reference_completion.rs
@@ -1,4 +1,4 @@
-use rustc_hash::{FxHashSet};
+use rustc_hash::FxHashSet;
 use ra_syntax::{
     SourceFileNode, AstNode,
     ast,
@@ -6,7 +6,7 @@ use ra_syntax::{
 };
 use hir::{
     self,
-    FnScopes, Def, Path
+    FnScopes, Path
 };
 
 use crate::{
@@ -53,7 +53,7 @@ pub(super) fn completions(
                         .add_to(acc)
                 });
         }
-        NameRefKind::Path(path) => complete_path(acc, db, module, path)?,
+        NameRefKind::Path(_) => (),
         NameRefKind::BareIdentInMod => (),
     }
     Ok(())
@@ -121,33 +121,6 @@ fn complete_fn(name_ref: ast::NameRef, scopes: &FnScopes, acc: &mut Completions)
     }
 }
 
-fn complete_path(
-    acc: &mut Completions,
-    db: &RootDatabase,
-    module: &hir::Module,
-    mut path: Path,
-) -> Cancelable<()> {
-    if path.segments.is_empty() {
-        return Ok(());
-    }
-    path.segments.pop();
-    let def_id = match module.resolve_path(db, path)? {
-        None => return Ok(()),
-        Some(it) => it,
-    };
-    let target_module = match def_id.resolve(db)? {
-        Def::Module(it) => it,
-        _ => return Ok(()),
-    };
-    let module_scope = target_module.scope(db)?;
-    module_scope.entries().for_each(|(name, _res)| {
-        CompletionItem::new(name.to_string())
-            .kind(Reference)
-            .add_to(acc)
-    });
-    Ok(())
-}
-
 #[cfg(test)]
 mod tests {
     use crate::completion::{CompletionKind, check_completion};