1 files changed, 104 insertions, 0 deletions

diff --git a/crates/ra_ide/src/parent_module.rs b/crates/ra_ide/src/parent_module.rs
new file mode 100644
index 000000000..6027e7d54
--- /dev/null
+++ b/crates/ra_ide/src/parent_module.rs
@@ -0,0 +1,104 @@
+//! FIXME: write short doc here
+
+use ra_db::{CrateId, FileId, FilePosition};
+
+use crate::{db::RootDatabase, NavigationTarget};
+
+/// This returns `Vec` because a module may be included from several places. We
+/// don't handle this case yet though, so the Vec has length at most one.
+pub(crate) fn parent_module(db: &RootDatabase, position: FilePosition) -> Vec<NavigationTarget> {
+    let src = hir::ModuleSource::from_position(db, position);
+    let module = match hir::Module::from_definition(
+        db,
+        hir::Source { file_id: position.file_id.into(), value: src },
+    ) {
+        None => return Vec::new(),
+        Some(it) => it,
+    };
+    let nav = NavigationTarget::from_module_to_decl(db, module);
+    vec![nav]
+}
+
+/// Returns `Vec` for the same reason as `parent_module`
+pub(crate) fn crate_for(db: &RootDatabase, file_id: FileId) -> Vec<CrateId> {
+    let src = hir::ModuleSource::from_file_id(db, file_id);
+    let module =
+        match hir::Module::from_definition(db, hir::Source { file_id: file_id.into(), value: src })
+        {
+            Some(it) => it,
+            None => return Vec::new(),
+        };
+    let krate = module.krate();
+    vec![krate.crate_id()]
+}
+
+#[cfg(test)]
+mod tests {
+    use ra_cfg::CfgOptions;
+    use ra_db::Env;
+
+    use crate::{
+        mock_analysis::{analysis_and_position, MockAnalysis},
+        AnalysisChange, CrateGraph,
+        Edition::Edition2018,
+    };
+
+    #[test]
+    fn test_resolve_parent_module() {
+        let (analysis, pos) = analysis_and_position(
+            "
+            //- /lib.rs
+            mod foo;
+            //- /foo.rs
+            <|>// empty
+            ",
+        );
+        let nav = analysis.parent_module(pos).unwrap().pop().unwrap();
+        nav.assert_match("foo MODULE FileId(1) [0; 8)");
+    }
+
+    #[test]
+    fn test_resolve_parent_module_for_inline() {
+        let (analysis, pos) = analysis_and_position(
+            "
+            //- /lib.rs
+            mod foo {
+                mod bar {
+                    mod baz { <|> }
+                }
+            }
+            ",
+        );
+        let nav = analysis.parent_module(pos).unwrap().pop().unwrap();
+        nav.assert_match("baz MODULE FileId(1) [32; 44)");
+    }
+
+    #[test]
+    fn test_resolve_crate_root() {
+        let mock = MockAnalysis::with_files(
+            "
+        //- /bar.rs
+        mod foo;
+        //- /foo.rs
+        // empty <|>
+    ",
+        );
+        let root_file = mock.id_of("/bar.rs");
+        let mod_file = mock.id_of("/foo.rs");
+        let mut host = mock.analysis_host();
+        assert!(host.analysis().crate_for(mod_file).unwrap().is_empty());
+
+        let mut crate_graph = CrateGraph::default();
+        let crate_id = crate_graph.add_crate_root(
+            root_file,
+            Edition2018,
+            CfgOptions::default(),
+            Env::default(),
+        );
+        let mut change = AnalysisChange::new();
+        change.set_crate_graph(crate_graph);
+        host.apply_change(change);
+
+        assert_eq!(host.analysis().crate_for(mod_file).unwrap(), vec![crate_id]);
+    }
+}