3 files changed, 138 insertions, 0 deletions

diff --git a/crates/ra_ide_api/src/impls.rs b/crates/ra_ide_api/src/impls.rs
new file mode 100644
index 000000000..469d56d63
--- /dev/null
+++ b/crates/ra_ide_api/src/impls.rs
@@ -0,0 +1,120 @@
+use ra_db::{SourceDatabase};
+use ra_syntax::{
+    AstNode, ast,
+    algo::find_node_at_offset,
+};
+use hir::{db::HirDatabase, source_binder};
+
+use crate::{FilePosition, NavigationTarget, db::RootDatabase, RangeInfo};
+
+pub(crate) fn goto_implementation(
+    db: &RootDatabase,
+    position: FilePosition,
+) -> Option<RangeInfo<Vec<NavigationTarget>>> {
+    let file = db.parse(position.file_id);
+    let syntax = file.syntax();
+
+    let module = source_binder::module_from_position(db, position)?;
+    let krate = module.krate(db)?;
+
+    let node = find_node_at_offset::<ast::NominalDef>(syntax, position.offset)?;
+    let ty = match node.kind() {
+        ast::NominalDefKind::StructDef(def) => {
+            source_binder::struct_from_module(db, module, &def).ty(db)
+        }
+        ast::NominalDefKind::EnumDef(def) => {
+            source_binder::enum_from_module(db, module, &def).ty(db)
+        }
+    };
+
+    let impls = db.impls_in_crate(krate);
+
+    let navs = impls
+        .lookup_impl_blocks(db, &ty)
+        .map(|(module, imp)| NavigationTarget::from_impl_block(db, module, &imp));
+
+    Some(RangeInfo::new(node.syntax().range(), navs.collect()))
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::mock_analysis::analysis_and_position;
+
+    fn check_goto(fixuture: &str, expected: &[&str]) {
+        let (analysis, pos) = analysis_and_position(fixuture);
+
+        let navs = analysis.goto_implementation(pos).unwrap().unwrap().info;
+        assert_eq!(navs.len(), expected.len());
+        navs.into_iter()
+            .enumerate()
+            .for_each(|(i, nav)| nav.assert_match(expected[i]));
+    }
+
+    #[test]
+    fn goto_implementation_works() {
+        check_goto(
+            "
+            //- /lib.rs
+            struct Foo<|>;
+            impl Foo {}
+            ",
+            &["impl IMPL_BLOCK FileId(1) [12; 23)"],
+        );
+    }
+
+    #[test]
+    fn goto_implementation_works_multiple_blocks() {
+        check_goto(
+            "
+            //- /lib.rs
+            struct Foo<|>;
+            impl Foo {}
+            impl Foo {}
+            ",
+            &[
+                "impl IMPL_BLOCK FileId(1) [12; 23)",
+                "impl IMPL_BLOCK FileId(1) [24; 35)",
+            ],
+        );
+    }
+
+    #[test]
+    fn goto_implementation_works_multiple_mods() {
+        check_goto(
+            "
+            //- /lib.rs
+            struct Foo<|>;
+            mod a {
+                impl super::Foo {}
+            }
+            mod b {
+                impl super::Foo {}
+            }
+            ",
+            &[
+                "impl IMPL_BLOCK FileId(1) [24; 42)",
+                "impl IMPL_BLOCK FileId(1) [57; 75)",
+            ],
+        );
+    }
+
+    #[test]
+    fn goto_implementation_works_multiple_files() {
+        check_goto(
+            "
+            //- /lib.rs
+            struct Foo<|>;
+            mod a;
+            mod b;
+            //- /a.rs
+            impl crate::Foo {}
+            //- /b.rs
+            impl crate::Foo {}
+            ",
+            &[
+                "impl IMPL_BLOCK FileId(2) [0; 18)",
+                "impl IMPL_BLOCK FileId(3) [0; 18)",
+            ],
+        );
+    }
+}
diff --git a/crates/ra_ide_api/src/lib.rs b/crates/ra_ide_api/src/lib.rs
index 09cf0216d..5d8acf9df 100644
--- a/crates/ra_ide_api/src/lib.rs
+++ b/crates/ra_ide_api/src/lib.rs
@@ -25,6 +25,7 @@ mod call_info;
 mod syntax_highlighting;
 mod parent_module;
 mod rename;
+mod impls;
 
 #[cfg(test)]
 mod marks;
@@ -416,6 +417,13 @@ impl Analysis {
         self.with_db(|db| goto_definition::goto_definition(db, position))
     }
 
+    pub fn goto_implementation(
+        &self,
+        position: FilePosition,
+    ) -> Cancelable<Option<RangeInfo<Vec<NavigationTarget>>>> {
+        self.with_db(|db| impls::goto_implementation(db, position))
+    }
+
     /// Finds all usages of the reference at point.
     pub fn find_all_refs(&self, position: FilePosition) -> Cancelable<Vec<(FileId, TextRange)>> {
         self.with_db(|db| db.find_all_refs(position))
diff --git a/crates/ra_ide_api/src/navigation_target.rs b/crates/ra_ide_api/src/navigation_target.rs
index d73d4afa7..5ccb5cc2e 100644
--- a/crates/ra_ide_api/src/navigation_target.rs
+++ b/crates/ra_ide_api/src/navigation_target.rs
@@ -147,6 +147,16 @@ impl NavigationTarget {
         }
     }
 
+    pub(crate) fn from_impl_block(
+        db: &RootDatabase,
+        module: hir::Module,
+        impl_block: &hir::ImplBlock,
+    ) -> NavigationTarget {
+        let (file_id, _) = module.definition_source(db);
+        let node = module.impl_source(db, impl_block.id());
+        NavigationTarget::from_syntax(file_id, "impl".into(), None, node.syntax())
+    }
+
     #[cfg(test)]
     pub(crate) fn assert_match(&self, expected: &str) {
         let actual = self.debug_render();