Merge #315

315: Split completion into manageable components r=matklad a=matklad

The main idea here is to do completion in two phases:

* first, we figure out surrounding context
* then, we run a series of completers on the given context. 

Co-authored-by: Aleksey Kladov <[email protected]>

1 files changed, 95 insertions, 0 deletions

diff --git a/crates/ra_analysis/src/completion/complete_path.rs b/crates/ra_analysis/src/completion/complete_path.rs
new file mode 100644
index 000000000..5fc24af72
--- /dev/null
+++ b/crates/ra_analysis/src/completion/complete_path.rs
@@ -0,0 +1,95 @@
+use crate::{
+    Cancelable,
+    completion::{CompletionItem, Completions, CompletionKind::*, CompletionContext},
+};
+
+pub(super) fn complete_path(acc: &mut Completions, ctx: &CompletionContext) -> Cancelable<()> {
+    let (path, module) = match (&ctx.path_prefix, &ctx.module) {
+        (Some(path), Some(module)) => (path.clone(), module),
+        _ => return Ok(()),
+    };
+    let def_id = match module.resolve_path(ctx.db, path)? {
+        Some(it) => it,
+        None => return Ok(()),
+    };
+    let target_module = match def_id.resolve(ctx.db)? {
+        hir::Def::Module(it) => it,
+        _ => return Ok(()),
+    };
+    let module_scope = target_module.scope(ctx.db)?;
+    module_scope.entries().for_each(|(name, _res)| {
+        CompletionItem::new(name.to_string())
+            .kind(Reference)
+            .add_to(acc)
+    });
+    Ok(())
+}
+
+#[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_use_item_starting_with_self() {
+        check_reference_completion(
+            r"
+            use self::m::<|>;
+
+            mod m {
+                struct Bar;
+            }
+            ",
+            "Bar",
+        );
+    }
+
+    #[test]
+    fn completes_use_item_starting_with_crate() {
+        check_reference_completion(
+            "
+            //- /lib.rs
+            mod foo;
+            struct Spam;
+            //- /foo.rs
+            use crate::Sp<|>
+            ",
+            "Spam;foo",
+        );
+    }
+
+    #[test]
+    fn completes_nested_use_tree() {
+        check_reference_completion(
+            "
+            //- /lib.rs
+            mod foo;
+            struct Spam;
+            //- /foo.rs
+            use crate::{Sp<|>};
+            ",
+            "Spam;foo",
+        );
+    }
+
+    #[test]
+    fn completes_deeply_nested_use_tree() {
+        check_reference_completion(
+            "
+            //- /lib.rs
+            mod foo;
+            pub mod bar {
+                pub mod baz {
+                    pub struct Spam;
+                }
+            }
+            //- /foo.rs
+            use crate::{bar::{baz::Sp<|>}};
+            ",
+            "Spam",
+        );
+    }
+}