5 files changed, 223 insertions, 322 deletions

diff --git a/crates/ra_analysis/src/completion.rs b/crates/ra_analysis/src/completion.rs
index d91304bc2..93edcc4c2 100644
--- a/crates/ra_analysis/src/completion.rs
+++ b/crates/ra_analysis/src/completion.rs
@@ -1,10 +1,10 @@
 mod completion_item;
-mod reference_completion;
 
 mod complete_fn_param;
 mod complete_keyword;
 mod complete_snippet;
 mod complete_path;
+mod complete_scope;
 
 use ra_editor::find_node_at_offset;
 use ra_text_edit::AtomTextEdit;
@@ -33,26 +33,16 @@ pub(crate) fn completions(
     position: FilePosition,
 ) -> Cancelable<Option<Completions>> {
     let original_file = db.source_file(position.file_id);
-    // Insert a fake ident to get a valid parse tree
-    let file = {
-        let edit = AtomTextEdit::insert(position.offset, "intellijRulezz".to_string());
-        original_file.reparse(&edit)
-    };
-    let module = ctry!(source_binder::module_from_position(db, position)?);
+    let ctx = ctry!(SyntaxContext::new(db, &original_file, position)?);
 
     let mut acc = Completions::default();
 
-    // First, let's try to complete a reference to some declaration.
-    if let Some(name_ref) = find_node_at_offset::<ast::NameRef>(file.syntax(), position.offset) {
-        reference_completion::completions(&mut acc, db, &module, &file, name_ref)?;
-    }
-
-    let ctx = ctry!(SyntaxContext::new(db, &original_file, position)?);
     complete_fn_param::complete_fn_param(&mut acc, &ctx);
     complete_keyword::complete_expr_keyword(&mut acc, &ctx);
     complete_snippet::complete_expr_snippet(&mut acc, &ctx);
     complete_snippet::complete_item_snippet(&mut acc, &ctx);
     complete_path::complete_path(&mut acc, &ctx)?;
+    complete_scope::complete_scope(&mut acc, &ctx)?;
 
     Ok(Some(acc))
 }
@@ -62,6 +52,7 @@ pub(crate) fn completions(
 #[derive(Debug)]
 pub(super) struct SyntaxContext<'a> {
     db: &'a db::RootDatabase,
+    offset: TextUnit,
     leaf: SyntaxNodeRef<'a>,
     module: Option<hir::Module>,
     enclosing_fn: Option<ast::FnDef<'a>>,
@@ -88,6 +79,7 @@ impl<'a> SyntaxContext<'a> {
         let mut ctx = SyntaxContext {
             db,
             leaf,
+            offset: position.offset,
             module,
             enclosing_fn: None,
             is_param: false,
diff --git a/crates/ra_analysis/src/completion/complete_path.rs b/crates/ra_analysis/src/completion/complete_path.rs
index d04503e46..8374ec346 100644
--- a/crates/ra_analysis/src/completion/complete_path.rs
+++ b/crates/ra_analysis/src/completion/complete_path.rs
@@ -9,8 +9,8 @@ pub(super) fn complete_path(acc: &mut Completions, ctx: &SyntaxContext) -> Cance
         _ => return Ok(()),
     };
     let def_id = match module.resolve_path(ctx.db, path)? {
-        None => return Ok(()),
         Some(it) => it,
+        None => return Ok(()),
     };
     let target_module = match def_id.resolve(ctx.db)? {
         hir::Def::Module(it) => it,
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..4ffd63016
--- /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::{
+    completion::{CompletionItem, Completions, CompletionKind::*, SyntaxContext},
+    Cancelable
+};
+
+pub(super) fn complete_scope(acc: &mut Completions, ctx: &SyntaxContext) -> 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 test_completion_let_scope() {
+        check_reference_completion(
+            r"
+            fn quux(x: i32) {
+                let y = 92;
+                1 + <|>;
+                let z = ();
+            }
+            ",
+            "y;x;quux",
+        );
+    }
+
+    #[test]
+    fn test_completion_if_let_scope() {
+        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 test_completion_for_scope() {
+        check_reference_completion(
+            r"
+            fn quux() {
+                for x in &[1, 2, 3] {
+                    <|>
+                }
+            }
+            ",
+            "x;quux",
+        );
+    }
+
+    #[test]
+    fn test_completion_mod_scope() {
+        check_reference_completion(
+            r"
+            struct Foo;
+            enum Baz {}
+            fn quux() {
+                <|>
+            }
+            ",
+            "quux;Foo;Baz",
+        );
+    }
+
+    #[test]
+    fn test_completion_mod_scope_nested() {
+        check_reference_completion(
+            r"
+            struct Foo;
+            mod m {
+                struct Bar;
+                fn quux() { <|> }
+            }
+            ",
+            "quux;Bar",
+        );
+    }
+
+    #[test]
+    fn test_complete_type() {
+        check_reference_completion(
+            r"
+            struct Foo;
+            fn x() -> <|>
+            ",
+            "Foo;x",
+        )
+    }
+
+    #[test]
+    fn test_complete_shadowing() {
+        check_reference_completion(
+            r"
+            fn foo() -> {
+                let bar = 92;
+                {
+                    let bar = 62;
+                    <|>
+                }
+            }
+            ",
+            "bar;foo",
+        )
+    }
+
+    #[test]
+    fn test_complete_self() {
+        check_reference_completion(r"impl S { fn foo(&self) { <|> } }", "self")
+    }
+}
diff --git a/crates/ra_analysis/src/completion/reference_completion.rs b/crates/ra_analysis/src/completion/reference_completion.rs
deleted file mode 100644
index 459ed8f6f..000000000
--- a/crates/ra_analysis/src/completion/reference_completion.rs
+++ /dev/null
@@ -1,307 +0,0 @@
-use rustc_hash::FxHashSet;
-use ra_syntax::{
-    SourceFileNode, AstNode,
-    ast,
-    SyntaxKind::*,
-};
-use hir::{
-    self,
-    FnScopes, Path
-};
-
-use crate::{
-    db::RootDatabase,
-    completion::{CompletionItem, Completions, CompletionKind::*},
-    Cancelable
-};
-
-pub(super) fn completions(
-    acc: &mut Completions,
-    db: &RootDatabase,
-    module: &hir::Module,
-    _file: &SourceFileNode,
-    name_ref: ast::NameRef,
-) -> Cancelable<()> {
-    let kind = match classify_name_ref(name_ref) {
-        Some(it) => it,
-        None => return Ok(()),
-    };
-
-    match kind {
-        NameRefKind::LocalRef { enclosing_fn } => {
-            if let Some(fn_def) = enclosing_fn {
-                let scopes = FnScopes::new(fn_def);
-                complete_fn(name_ref, &scopes, acc);
-            }
-
-            let module_scope = module.scope(db)?;
-            module_scope
-                .entries()
-                .filter(|(_name, res)| {
-                    // Don't expose this item
-                    match res.import {
-                        None => true,
-                        Some(import) => {
-                            let range = import.range(db, module.source().file_id());
-                            !range.is_subrange(&name_ref.syntax().range())
-                        }
-                    }
-                })
-                .for_each(|(name, _res)| {
-                    CompletionItem::new(name.to_string())
-                        .kind(Reference)
-                        .add_to(acc)
-                });
-        }
-        NameRefKind::Path(_) => (),
-        NameRefKind::BareIdentInMod => (),
-    }
-    Ok(())
-}
-
-enum NameRefKind<'a> {
-    /// NameRef is a part of single-segment path, for example, a refernece to a
-    /// local variable.
-    LocalRef {
-        enclosing_fn: Option<ast::FnDef<'a>>,
-    },
-    /// NameRef is the last segment in some path
-    Path(Path),
-    /// NameRef is bare identifier at the module's root.
-    /// Used for keyword completion
-    BareIdentInMod,
-}
-
-fn classify_name_ref(name_ref: ast::NameRef) -> Option<NameRefKind> {
-    let name_range = name_ref.syntax().range();
-    let top_node = name_ref
-        .syntax()
-        .ancestors()
-        .take_while(|it| it.range() == name_range)
-        .last()
-        .unwrap();
-    match top_node.parent().map(|it| it.kind()) {
-        Some(SOURCE_FILE) | Some(ITEM_LIST) => return Some(NameRefKind::BareIdentInMod),
-        _ => (),
-    }
-
-    let parent = name_ref.syntax().parent()?;
-    if let Some(segment) = ast::PathSegment::cast(parent) {
-        let path = segment.parent_path();
-        if let Some(path) = Path::from_ast(path) {
-            if !path.is_ident() {
-                return Some(NameRefKind::Path(path));
-            }
-        }
-        if path.qualifier().is_none() {
-            let enclosing_fn = name_ref
-                .syntax()
-                .ancestors()
-                .take_while(|it| it.kind() != SOURCE_FILE && it.kind() != MODULE)
-                .find_map(ast::FnDef::cast);
-            return Some(NameRefKind::LocalRef { enclosing_fn });
-        }
-    }
-    None
-}
-
-fn complete_fn(name_ref: ast::NameRef, scopes: &FnScopes, acc: &mut Completions) {
-    let mut shadowed = FxHashSet::default();
-    scopes
-        .scope_chain(name_ref.syntax())
-        .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 test_completion_let_scope() {
-        check_reference_completion(
-            r"
-            fn quux(x: i32) {
-                let y = 92;
-                1 + <|>;
-                let z = ();
-            }
-            ",
-            "y;x;quux",
-        );
-    }
-
-    #[test]
-    fn test_completion_if_let_scope() {
-        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 test_completion_for_scope() {
-        check_reference_completion(
-            r"
-            fn quux() {
-                for x in &[1, 2, 3] {
-                    <|>
-                }
-            }
-            ",
-            "x;quux",
-        );
-    }
-
-    #[test]
-    fn test_completion_mod_scope() {
-        check_reference_completion(
-            r"
-            struct Foo;
-            enum Baz {}
-            fn quux() {
-                <|>
-            }
-            ",
-            "quux;Foo;Baz",
-        );
-    }
-
-    #[test]
-    fn test_completion_mod_scope_no_self_use() {
-        check_reference_completion(
-            r"
-            use foo<|>;
-            ",
-            "",
-        );
-    }
-
-    #[test]
-    fn test_completion_self_path() {
-        check_reference_completion(
-            r"
-            use self::m::<|>;
-
-            mod m {
-                struct Bar;
-            }
-            ",
-            "Bar",
-        );
-    }
-
-    #[test]
-    fn test_completion_mod_scope_nested() {
-        check_reference_completion(
-            r"
-            struct Foo;
-            mod m {
-                struct Bar;
-                fn quux() { <|> }
-            }
-            ",
-            "quux;Bar",
-        );
-    }
-
-    #[test]
-    fn test_complete_type() {
-        check_reference_completion(
-            r"
-            struct Foo;
-            fn x() -> <|>
-            ",
-            "Foo;x",
-        )
-    }
-
-    #[test]
-    fn test_complete_shadowing() {
-        check_reference_completion(
-            r"
-            fn foo() -> {
-                let bar = 92;
-                {
-                    let bar = 62;
-                    <|>
-                }
-            }
-            ",
-            "bar;foo",
-        )
-    }
-
-    #[test]
-    fn test_complete_self() {
-        check_reference_completion(r"impl S { fn foo(&self) { <|> } }", "self")
-    }
-
-    #[test]
-    fn test_complete_crate_path() {
-        check_reference_completion(
-            "
-            //- /lib.rs
-            mod foo;
-            struct Spam;
-            //- /foo.rs
-            use crate::Sp<|>
-            ",
-            "Spam;foo",
-        );
-    }
-
-    #[test]
-    fn test_complete_crate_path_with_braces() {
-        check_reference_completion(
-            "
-            //- /lib.rs
-            mod foo;
-            struct Spam;
-            //- /foo.rs
-            use crate::{Sp<|>};
-            ",
-            "Spam;foo",
-        );
-    }
-
-    #[test]
-    fn test_complete_crate_path_in_nested_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",
-        );
-    }
-}
diff --git a/crates/ra_hir/src/function/scope.rs b/crates/ra_hir/src/function/scope.rs
index 863453291..9f1aa1ef2 100644
--- a/crates/ra_hir/src/function/scope.rs
+++ b/crates/ra_hir/src/function/scope.rs
@@ -1,7 +1,7 @@
 use rustc_hash::{FxHashMap, FxHashSet};
 
 use ra_syntax::{
-    AstNode, SmolStr, SyntaxNodeRef, TextRange,
+    AstNode, SmolStr, SyntaxNodeRef, TextUnit, TextRange,
     algo::generate,
     ast::{self, ArgListOwner, LoopBodyOwner, NameOwner},
 };
@@ -57,6 +57,48 @@ impl FnScopes {
             self.scopes[scope].parent
         })
     }
+    pub fn scope_chain_for_offset<'a>(
+        &'a self,
+        offset: TextUnit,
+    ) -> impl Iterator<Item = ScopeId> + 'a {
+        let scope = self
+            .scope_for
+            .iter()
+            // find containin scope
+            .min_by_key(|(ptr, _scope)| {
+                (
+                    !(ptr.range().start() <= offset && offset <= ptr.range().end()),
+                    ptr.range().len(),
+                )
+            })
+            .map(|(ptr, scope)| self.adjust(*ptr, *scope, offset));
+
+        generate(scope, move |&scope| self.scopes[scope].parent)
+    }
+    // XXX: during completion, cursor might be outside of any particular
+    // expression. Try to figure out the correct scope...
+    fn adjust(&self, ptr: LocalSyntaxPtr, original_scope: ScopeId, offset: TextUnit) -> ScopeId {
+        let r = ptr.range();
+        let child_scopes = self
+            .scope_for
+            .iter()
+            .map(|(ptr, scope)| (ptr.range(), scope))
+            .filter(|(range, _)| range.start() <= offset && range.is_subrange(&r) && *range != r);
+
+        child_scopes
+            .max_by(|(r1, _), (r2, _)| {
+                if r2.is_subrange(&r1) {
+                    std::cmp::Ordering::Greater
+                } else if r1.is_subrange(&r2) {
+                    std::cmp::Ordering::Less
+                } else {
+                    r1.start().cmp(&r2.start())
+                }
+            })
+            .map(|(ptr, scope)| *scope)
+            .unwrap_or(original_scope)
+    }
+
     pub fn resolve_local_name<'a>(&'a self, name_ref: ast::NameRef) -> Option<&'a ScopeEntry> {
         let mut shadowed = FxHashSet::default();
         let ret = self
@@ -144,6 +186,8 @@ impl ScopeEntry {
 }
 
 fn compute_block_scopes(block: ast::Block, scopes: &mut FnScopes, mut scope: ScopeId) {
+    // A hack for completion :(
+    scopes.set_scope(block.syntax(), scope);
     for stmt in block.statements() {
         match stmt {
             ast::Stmt::LetStmt(stmt) => {
@@ -165,6 +209,7 @@ fn compute_block_scopes(block: ast::Block, scopes: &mut FnScopes, mut scope: Sco
         }
     }
     if let Some(expr) = block.expr() {
+        eprintln!("{:?}", expr);
         scopes.set_scope(expr.syntax(), scope);
         compute_expr_scopes(expr, scopes, scope);
     }