3 files changed, 24 insertions, 1 deletions

diff --git a/crates/ra_analysis/src/db.rs b/crates/ra_analysis/src/db.rs
index 94729d296..780a84291 100644
--- a/crates/ra_analysis/src/db.rs
+++ b/crates/ra_analysis/src/db.rs
@@ -93,6 +93,8 @@ salsa::database_storage! {
             fn item_map() for hir::db::ItemMapQuery;
             fn fn_syntax() for hir::db::FnSyntaxQuery;
             fn submodules() for hir::db::SubmodulesQuery;
+            fn infer() for hir::db::InferQuery;
+            fn type_for_def() for hir::db::TypeForDefQuery;
         }
     }
 }
diff --git a/crates/ra_analysis/src/imp.rs b/crates/ra_analysis/src/imp.rs
index 00cdf7eff..a547c5a20 100644
--- a/crates/ra_analysis/src/imp.rs
+++ b/crates/ra_analysis/src/imp.rs
@@ -5,7 +5,8 @@ use std::{
 
 use ra_editor::{self, find_node_at_offset, FileSymbol, LineIndex, LocalEdit, Severity};
 use ra_syntax::{
-    ast::{self, ArgListOwner, Expr, NameOwner},
+    ast::{self, ArgListOwner, Expr, NameOwner, FnDef},
+    algo::find_covering_node,
     AstNode, SourceFileNode,
     SyntaxKind::*,
     SyntaxNodeRef, TextRange, TextUnit,
@@ -513,6 +514,23 @@ impl AnalysisImpl {
         Ok(None)
     }
 
+    pub fn type_of(&self, file_id: FileId, range: TextRange) -> Cancelable<Option<String>> {
+        let file = self.db.source_file(file_id);
+        let syntax = file.syntax();
+        let node = find_covering_node(syntax, range);
+        let parent_fn = node.ancestors().filter_map(FnDef::cast).next();
+        let parent_fn = if let Some(p) = parent_fn {
+            p
+        } else {
+            return Ok(None);
+        };
+        let function = ctry!(source_binder::function_from_source(
+            &*self.db, file_id, parent_fn
+        )?);
+        let infer = function.infer(&*self.db)?;
+        Ok(infer.type_of_node(node).map(|t| t.to_string()))
+    }
+
     fn index_resolve(&self, name_ref: ast::NameRef) -> Cancelable<Vec<(FileId, FileSymbol)>> {
         let name = name_ref.text();
         let mut query = Query::new(name.to_string());
diff --git a/crates/ra_analysis/src/lib.rs b/crates/ra_analysis/src/lib.rs
index fbb19ed6b..a029f66b4 100644
--- a/crates/ra_analysis/src/lib.rs
+++ b/crates/ra_analysis/src/lib.rs
@@ -366,6 +366,9 @@ impl Analysis {
     ) -> Cancelable<Option<(FnSignatureInfo, Option<usize>)>> {
         self.imp.resolve_callable(position)
     }
+    pub fn type_of(&self, file_id: FileId, range: TextRange) -> Cancelable<Option<String>> {
+        self.imp.type_of(file_id, range)
+    }
 }
 
 pub struct LibraryData {