1 files changed, 171 insertions, 0 deletions

diff --git a/crates/ra_analysis/src/completion/complete_scope.rs b/crates/ra_analysis/src/completion/complete_scope.rs
new file mode 100644
index 000000000..d07c0e46d
--- /dev/null
+++ b/crates/ra_analysis/src/completion/complete_scope.rs
@@ -0,0 +1,171 @@
+use rustc_hash::FxHashSet;
+use ra_syntax::TextUnit;
+
+use crate::{
+    Cancelable,
+    completion::{CompletionItem, Completions, CompletionKind::*, CompletionContext},
+};
+
+pub(super) fn complete_scope(acc: &mut Completions, ctx: &CompletionContext) -> Cancelable<()> {
+    if !ctx.is_trivial_path {
+        return Ok(());
+    }
+    if let Some(fn_def) = ctx.enclosing_fn {
+        let scopes = hir::FnScopes::new(fn_def);
+        complete_fn(acc, &scopes, ctx.offset);
+    }
+
+    if let Some(module) = &ctx.module {
+        let module_scope = module.scope(ctx.db)?;
+        module_scope
+            .entries()
+            .filter(|(_name, res)| {
+                // Don't expose this item
+                match res.import {
+                    None => true,
+                    Some(import) => {
+                        let range = import.range(ctx.db, module.source().file_id());
+                        !range.is_subrange(&ctx.leaf.range())
+                    }
+                }
+            })
+            .for_each(|(name, _res)| {
+                CompletionItem::new(name.to_string())
+                    .kind(Reference)
+                    .add_to(acc)
+            });
+    }
+
+    Ok(())
+}
+
+fn complete_fn(acc: &mut Completions, scopes: &hir::FnScopes, offset: TextUnit) {
+    let mut shadowed = FxHashSet::default();
+    scopes
+        .scope_chain_for_offset(offset)
+        .flat_map(|scope| scopes.entries(scope).iter())
+        .filter(|entry| shadowed.insert(entry.name()))
+        .for_each(|entry| {
+            CompletionItem::new(entry.name().to_string())
+                .kind(Reference)
+                .add_to(acc)
+        });
+    if scopes.self_param.is_some() {
+        CompletionItem::new("self").kind(Reference).add_to(acc);
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::completion::{CompletionKind, check_completion};
+
+    fn check_reference_completion(code: &str, expected_completions: &str) {
+        check_completion(code, expected_completions, CompletionKind::Reference);
+    }
+
+    #[test]
+    fn completes_bindings_from_let() {
+        check_reference_completion(
+            r"
+            fn quux(x: i32) {
+                let y = 92;
+                1 + <|>;
+                let z = ();
+            }
+            ",
+            "y;x;quux",
+        );
+    }
+
+    #[test]
+    fn completes_bindings_from_if_let() {
+        check_reference_completion(
+            r"
+            fn quux() {
+                if let Some(x) = foo() {
+                    let y = 92;
+                };
+                if let Some(a) = bar() {
+                    let b = 62;
+                    1 + <|>
+                }
+            }
+            ",
+            "b;a;quux",
+        );
+    }
+
+    #[test]
+    fn completes_bindings_from_for() {
+        check_reference_completion(
+            r"
+            fn quux() {
+                for x in &[1, 2, 3] {
+                    <|>
+                }
+            }
+            ",
+            "x;quux",
+        );
+    }
+
+    #[test]
+    fn completes_module_items() {
+        check_reference_completion(
+            r"
+            struct Foo;
+            enum Baz {}
+            fn quux() {
+                <|>
+            }
+            ",
+            "quux;Foo;Baz",
+        );
+    }
+
+    #[test]
+    fn completes_module_items_in_nested_modules() {
+        check_reference_completion(
+            r"
+            struct Foo;
+            mod m {
+                struct Bar;
+                fn quux() { <|> }
+            }
+            ",
+            "quux;Bar",
+        );
+    }
+
+    #[test]
+    fn completes_return_type() {
+        check_reference_completion(
+            r"
+            struct Foo;
+            fn x() -> <|>
+            ",
+            "Foo;x",
+        )
+    }
+
+    #[test]
+    fn dont_show_to_completions_for_shadowing() {
+        check_reference_completion(
+            r"
+            fn foo() -> {
+                let bar = 92;
+                {
+                    let bar = 62;
+                    <|>
+                }
+            }
+            ",
+            "bar;foo",
+        )
+    }
+
+    #[test]
+    fn completes_self_in_methods() {
+        check_reference_completion(r"impl S { fn foo(&self) { <|> } }", "self")
+    }
+}