4 files changed, 67 insertions, 5 deletions

diff --git a/crates/ra_hir/src/code_model_api.rs b/crates/ra_hir/src/code_model_api.rs
index 6bbc80e17..236cb3ab4 100644
--- a/crates/ra_hir/src/code_model_api.rs
+++ b/crates/ra_hir/src/code_model_api.rs
@@ -1,7 +1,7 @@
 use ra_db::{CrateId, Cancelable, FileId};
 use ra_syntax::ast;
 
-use crate::{Name, db::HirDatabase, DefId};
+use crate::{Name, db::HirDatabase, DefId, Path, PerNs};
 
 /// hir::Crate describes a single crate. It's the main inteface with which
 /// crate's dependencies interact. Mostly, it should be just a proxy for the
@@ -52,4 +52,12 @@ impl Module {
     pub fn child(&self, db: &impl HirDatabase, name: &Name) -> Cancelable<Option<Module>> {
         self.child_impl(db, name)
     }
+    /// Finds a parent module.
+    pub fn parent(&self, db: &impl HirDatabase) -> Cancelable<Option<Module>> {
+        self.parent_impl(db)
+    }
+
+    pub fn resolve_path(&self, db: &impl HirDatabase, path: &Path) -> Cancelable<PerNs<DefId>> {
+        self.resolve_path_impl(db, path)
+    }
 }
diff --git a/crates/ra_hir/src/code_model_impl.rs b/crates/ra_hir/src/code_model_impl.rs
index 83ee8186e..678758956 100644
--- a/crates/ra_hir/src/code_model_impl.rs
+++ b/crates/ra_hir/src/code_model_impl.rs
@@ -1,7 +1,7 @@
 use ra_db::{CrateId, Cancelable, FileId};
 use ra_syntax::{AstNode, ast};
 
-use crate::{HirFileId, db::HirDatabase, Crate, CrateDependency, AsName, DefId, DefLoc, DefKind, Name};
+use crate::{HirFileId, db::HirDatabase, Crate, CrateDependency, AsName, DefId, DefLoc, DefKind, Name, Path, PathKind, PerNs, Def};
 
 use crate::code_model_api::Module;
 
@@ -102,4 +102,58 @@ impl Module {
         let module = Module::new(def_id);
         Ok(Some(module))
     }
+    pub fn parent_impl(&self, db: &impl HirDatabase) -> Cancelable<Option<Module>> {
+        let loc = self.def_id.loc(db);
+        let module_tree = db.module_tree(loc.source_root_id)?;
+        let parent_id = ctry!(loc.module_id.parent(&module_tree));
+        let def_loc = DefLoc {
+            module_id: parent_id,
+            source_item_id: parent_id.source(&module_tree).0,
+            ..loc
+        };
+        let def_id = def_loc.id(db);
+        let module = Module::new(def_id);
+        Ok(Some(module))
+    }
+    pub fn resolve_path_impl(
+        &self,
+        db: &impl HirDatabase,
+        path: &Path,
+    ) -> Cancelable<PerNs<DefId>> {
+        let mut curr_per_ns = PerNs::types(
+            match path.kind {
+                PathKind::Crate => self.crate_root(db)?,
+                PathKind::Self_ | PathKind::Plain => self.clone(),
+                PathKind::Super => {
+                    if let Some(p) = self.parent(db)? {
+                        p
+                    } else {
+                        return Ok(PerNs::none());
+                    }
+                }
+            }
+            .def_id,
+        );
+
+        let segments = &path.segments;
+        for name in segments.iter() {
+            let curr = if let Some(r) = curr_per_ns.as_ref().take_types() {
+                r
+            } else {
+                return Ok(PerNs::none());
+            };
+            let module = match curr.resolve(db)? {
+                Def::Module(it) => it,
+                // TODO here would be the place to handle enum variants...
+                _ => return Ok(PerNs::none()),
+            };
+            let scope = module.scope(db)?;
+            curr_per_ns = if let Some(r) = scope.get(&name) {
+                r.def_id
+            } else {
+                return Ok(PerNs::none());
+            };
+        }
+        Ok(curr_per_ns)
+    }
 }
diff --git a/crates/ra_hir/src/module.rs b/crates/ra_hir/src/module.rs
index f0b673908..11e3f6782 100644
--- a/crates/ra_hir/src/module.rs
+++ b/crates/ra_hir/src/module.rs
@@ -251,7 +251,7 @@ impl ModuleId {
     fn parent_link(self, tree: &ModuleTree) -> Option<LinkId> {
         tree.mods[self].parent
     }
-    fn parent(self, tree: &ModuleTree) -> Option<ModuleId> {
+    pub(crate) fn parent(self, tree: &ModuleTree) -> Option<ModuleId> {
         let link = self.parent_link(tree)?;
         Some(tree.links[link].owner)
     }
diff --git a/crates/ra_hir/src/module/nameres.rs b/crates/ra_hir/src/module/nameres.rs
index 059301b05..dac524384 100644
--- a/crates/ra_hir/src/module/nameres.rs
+++ b/crates/ra_hir/src/module/nameres.rs
@@ -177,11 +177,11 @@ impl<T> PerNs<T> {
     }
 
     pub fn take_types(self) -> Option<T> {
-        self.types
+        self.take(Namespace::Types)
     }
 
     pub fn take_values(self) -> Option<T> {
-        self.values
+        self.take(Namespace::Values)
     }
 
     pub fn get(&self, namespace: Namespace) -> Option<&T> {