1 files changed, 139 insertions, 0 deletions

diff --git a/crates/ra_ide_api/src/goto_defenition.rs b/crates/ra_ide_api/src/goto_defenition.rs
new file mode 100644
index 000000000..fcd8d315e
--- /dev/null
+++ b/crates/ra_ide_api/src/goto_defenition.rs
@@ -0,0 +1,139 @@
+use ra_db::{FileId, Cancelable, SyntaxDatabase};
+use ra_syntax::{
+    TextRange, AstNode, ast, SyntaxKind::{NAME, MODULE},
+    algo::find_node_at_offset,
+};
+
+use crate::{FilePosition, NavigationTarget, db::RootDatabase};
+
+pub(crate) fn goto_defenition(
+    db: &RootDatabase,
+    position: FilePosition,
+) -> Cancelable<Option<Vec<NavigationTarget>>> {
+    let file = db.source_file(position.file_id);
+    let syntax = file.syntax();
+    if let Some(name_ref) = find_node_at_offset::<ast::NameRef>(syntax, position.offset) {
+        return Ok(Some(reference_defenition(db, position.file_id, name_ref)?));
+    }
+    if let Some(name) = find_node_at_offset::<ast::Name>(syntax, position.offset) {
+        return name_defenition(db, position.file_id, name);
+    }
+    Ok(None)
+}
+
+pub(crate) fn reference_defenition(
+    db: &RootDatabase,
+    file_id: FileId,
+    name_ref: &ast::NameRef,
+) -> Cancelable<Vec<NavigationTarget>> {
+    if let Some(fn_descr) =
+        hir::source_binder::function_from_child_node(db, file_id, name_ref.syntax())?
+    {
+        let scope = fn_descr.scopes(db)?;
+        // First try to resolve the symbol locally
+        if let Some(entry) = scope.resolve_local_name(name_ref) {
+            let nav = NavigationTarget {
+                file_id,
+                name: entry.name().to_string().into(),
+                range: entry.ptr().range(),
+                kind: NAME,
+                ptr: None,
+            };
+            return Ok(vec![nav]);
+        };
+    }
+    // If that fails try the index based approach.
+    let navs = db
+        .index_resolve(name_ref)?
+        .into_iter()
+        .map(NavigationTarget::from_symbol)
+        .collect();
+    Ok(navs)
+}
+
+fn name_defenition(
+    db: &RootDatabase,
+    file_id: FileId,
+    name: &ast::Name,
+) -> Cancelable<Option<Vec<NavigationTarget>>> {
+    if let Some(module) = name.syntax().parent().and_then(ast::Module::cast) {
+        if module.has_semi() {
+            if let Some(child_module) =
+                hir::source_binder::module_from_declaration(db, file_id, module)?
+            {
+                let (file_id, _) = child_module.defenition_source(db)?;
+                let name = match child_module.name(db)? {
+                    Some(name) => name.to_string().into(),
+                    None => "".into(),
+                };
+                let nav = NavigationTarget {
+                    file_id,
+                    name,
+                    range: TextRange::offset_len(0.into(), 0.into()),
+                    kind: MODULE,
+                    ptr: None,
+                };
+                return Ok(Some(vec![nav]));
+            }
+        }
+    }
+    Ok(None)
+}
+
+#[cfg(test)]
+mod tests {
+    use test_utils::assert_eq_dbg;
+    use crate::mock_analysis::analysis_and_position;
+
+    #[test]
+    fn goto_defenition_works_in_items() {
+        let (analysis, pos) = analysis_and_position(
+            "
+            //- /lib.rs
+            struct Foo;
+            enum E { X(Foo<|>) }
+            ",
+        );
+
+        let symbols = analysis.goto_defenition(pos).unwrap().unwrap();
+        assert_eq_dbg(
+            r#"[NavigationTarget { file_id: FileId(1), name: "Foo",
+                                   kind: STRUCT_DEF, range: [0; 11),
+                                   ptr: Some(LocalSyntaxPtr { range: [0; 11), kind: STRUCT_DEF }) }]"#,
+            &symbols,
+        );
+    }
+
+    #[test]
+    fn goto_defenition_works_for_module_declaration() {
+        let (analysis, pos) = analysis_and_position(
+            "
+            //- /lib.rs
+            mod <|>foo;
+            //- /foo.rs
+            // empty
+        ",
+        );
+
+        let symbols = analysis.goto_defenition(pos).unwrap().unwrap();
+        assert_eq_dbg(
+            r#"[NavigationTarget { file_id: FileId(2), name: "foo", kind: MODULE, range: [0; 0), ptr: None }]"#,
+            &symbols,
+        );
+
+        let (analysis, pos) = analysis_and_position(
+            "
+            //- /lib.rs
+            mod <|>foo;
+            //- /foo/mod.rs
+            // empty
+        ",
+        );
+
+        let symbols = analysis.goto_defenition(pos).unwrap().unwrap();
+        assert_eq_dbg(
+            r#"[NavigationTarget { file_id: FileId(2), name: "foo", kind: MODULE, range: [0; 0), ptr: None }]"#,
+            &symbols,
+        );
+    }
+}