13 files changed, 144 insertions, 29 deletions

diff --git a/crates/libanalysis/src/lib.rs b/crates/libanalysis/src/lib.rs
index c84ab6077..a3f721cc8 100644
--- a/crates/libanalysis/src/lib.rs
+++ b/crates/libanalysis/src/lib.rs
@@ -32,7 +32,7 @@ use libsyntax2::{
     ast::{self, AstNode, NameOwner},
     SyntaxKind::*,
 };
-use libeditor::{LineIndex, FileSymbol, find_node};
+use libeditor::{LineIndex, FileSymbol, find_node_at_offset};
 
 use self::{
     symbol_index::FileSymbols,
@@ -183,10 +183,10 @@ impl World {
     ) -> Result<Vec<(FileId, FileSymbol)>> {
         let file = self.file_syntax(id)?;
         let syntax = file.syntax();
-        if let Some(name_ref) = find_node::<ast::NameRef>(syntax, offset) {
+        if let Some(name_ref) = find_node_at_offset::<ast::NameRef>(syntax, offset) {
             return Ok(self.index_resolve(name_ref));
         }
-        if let Some(name) = find_node::<ast::Name>(syntax, offset) {
+        if let Some(name) = find_node_at_offset::<ast::Name>(syntax, offset) {
             if let Some(module) = name.syntax().parent().and_then(ast::Module::cast) {
                 if module.has_semi() {
                     let file_ids = self.resolve_module(id, module);
diff --git a/crates/libeditor/src/code_actions.rs b/crates/libeditor/src/code_actions.rs
index b3305be2a..f53a8f9c6 100644
--- a/crates/libeditor/src/code_actions.rs
+++ b/crates/libeditor/src/code_actions.rs
@@ -3,7 +3,7 @@ use std::{
 };
 
 use libsyntax2::{
-    File,
+    File, TextUnit,
     ast::{self, AstNode, AttrsOwner, TypeParamsOwner, NameOwner},
     SyntaxKind::COMMA,
     SyntaxNodeRef,
@@ -13,7 +13,7 @@ use libsyntax2::{
     },
 };
 
-use {TextUnit, EditBuilder, Edit};
+use {EditBuilder, Edit, find_node_at_offset};
 
 #[derive(Debug)]
 pub struct ActionResult {
@@ -39,7 +39,7 @@ pub fn flip_comma<'a>(file: &'a File, offset: TextUnit) -> Option<impl FnOnce()
 }
 
 pub fn add_derive<'a>(file: &'a File, offset: TextUnit) -> Option<impl FnOnce() -> ActionResult + 'a> {
-    let nominal = find_node::<ast::NominalDef>(file.syntax(), offset)?;
+    let nominal = find_node_at_offset::<ast::NominalDef>(file.syntax(), offset)?;
     Some(move || {
         let derive_attr = nominal
             .attrs()
@@ -66,7 +66,7 @@ pub fn add_derive<'a>(file: &'a File, offset: TextUnit) -> Option<impl FnOnce()
 }
 
 pub fn add_impl<'a>(file: &'a File, offset: TextUnit) -> Option<impl FnOnce() -> ActionResult + 'a> {
-    let nominal = find_node::<ast::NominalDef>(file.syntax(), offset)?;
+    let nominal = find_node_at_offset::<ast::NominalDef>(file.syntax(), offset)?;
     let name = nominal.name()?;
 
     Some(move || {
@@ -105,16 +105,6 @@ fn non_trivia_sibling(node: SyntaxNodeRef, direction: Direction) -> Option<Synta
         .find(|node| !node.kind().is_trivia())
 }
 
-pub fn find_node<'a, N: AstNode<'a>>(syntax: SyntaxNodeRef<'a>, offset: TextUnit) -> Option<N> {
-    let leaves = find_leaf_at_offset(syntax, offset);
-    let leaf = leaves.clone()
-        .find(|leaf| !leaf.kind().is_trivia())
-        .or_else(|| leaves.right_biased())?;
-    ancestors(leaf)
-        .filter_map(N::cast)
-        .next()
-}
-
 fn comma_list(buf: &mut String, bra: &str, ket: &str, items: impl Iterator<Item=impl fmt::Display>) {
     buf.push_str(bra);
     let mut first = true;
diff --git a/crates/libeditor/src/completion.rs b/crates/libeditor/src/completion.rs
new file mode 100644
index 000000000..cf61ec784
--- /dev/null
+++ b/crates/libeditor/src/completion.rs
@@ -0,0 +1,31 @@
+use libsyntax2::{
+    File, TextUnit,
+    ast,
+    algo::find_leaf_at_offset,
+};
+
+use {
+    AtomEdit, find_node_at_offset,
+};
+
+#[derive(Debug)]
+pub struct CompletionItem {
+    name: String,
+}
+
+pub fn scope_completion(file: &File, offset: TextUnit) -> Option<Vec<CompletionItem>> {
+    // Insert a fake ident to get a valid parse tree
+    let file = {
+        let edit = AtomEdit::insert(offset, "intellijRulezz".to_string());
+        // Don't bother with completion if incremental reparse fails
+        file.incremental_reparse(&edit)?
+    };
+    let name_ref = find_node_at_offset::<ast::NameRef>(file.syntax(), offset)?;
+    Some(complete(name_ref))
+}
+
+fn complete(name_ref: ast::NameRef) -> Vec<CompletionItem> {
+    vec![CompletionItem {
+        name: "foo".to_string()
+    }]
+}
diff --git a/crates/libeditor/src/lib.rs b/crates/libeditor/src/lib.rs
index 55302265f..60489f7e3 100644
--- a/crates/libeditor/src/lib.rs
+++ b/crates/libeditor/src/lib.rs
@@ -8,11 +8,12 @@ mod line_index;
 mod edit;
 mod code_actions;
 mod typing;
+mod completion;
 
 use libsyntax2::{
-    File, TextUnit, TextRange,
+    File, TextUnit, TextRange, SyntaxNodeRef,
     ast::{AstNode, NameOwner},
-    algo::{walk, find_leaf_at_offset},
+    algo::{walk, find_leaf_at_offset, ancestors},
     SyntaxKind::{self, *},
 };
 pub use libsyntax2::AtomEdit;
@@ -22,10 +23,11 @@ pub use self::{
     symbols::{StructureNode, file_structure, FileSymbol, file_symbols},
     edit::{EditBuilder, Edit},
     code_actions::{
-        ActionResult, find_node,
+        ActionResult,
         flip_comma, add_derive, add_impl,
     },
     typing::join_lines,
+    completion::scope_completion,
 };
 
 #[derive(Debug)]
@@ -138,3 +140,16 @@ pub fn runnables(file: &File) -> Vec<Runnable> {
         })
         .collect()
 }
+
+pub fn find_node_at_offset<'a, N: AstNode<'a>>(
+    syntax: SyntaxNodeRef<'a>,
+    offset: TextUnit,
+) -> Option<N> {
+    let leaves = find_leaf_at_offset(syntax, offset);
+    let leaf = leaves.clone()
+        .find(|leaf| !leaf.kind().is_trivia())
+        .or_else(|| leaves.right_biased())?;
+    ancestors(leaf)
+        .filter_map(N::cast)
+        .next()
+}
diff --git a/crates/libeditor/tests/test.rs b/crates/libeditor/tests/test.rs
index c8882c94d..9d59f4cdf 100644
--- a/crates/libeditor/tests/test.rs
+++ b/crates/libeditor/tests/test.rs
@@ -9,7 +9,7 @@ use libeditor::{
     ActionResult,
     highlight, runnables, extend_selection, file_structure,
     flip_comma, add_derive, add_impl, matching_brace,
-    join_lines,
+    join_lines, scope_completion,
 };
 
 #[test]
@@ -244,6 +244,26 @@ struct Foo { f: u32 }
 ");
 }
 
+// #[test]
+// fn test_completion() {
+//     fn do_check(code: &str, expected_completions: &str) {
+//         let (off, code) = extract_offset(&code);
+//         let file = file(&code);
+//         let completions = scope_completion(&file, off).unwrap();
+//         assert_eq_dbg(expected_completions, &completions);
+//     }
+
+//     do_check(r"
+// fn foo(foo: i32) {
+//     let bar = 92;
+//     1 + <|>
+// }
+// ", r#"
+// CompletionItem { name: "bar" },
+// CompletionItem { name: "foo" },
+// "#);
+// }
+
 fn file(text: &str) -> File {
     File::parse(text)
 }
diff --git a/crates/libsyntax2/src/grammar/items/mod.rs b/crates/libsyntax2/src/grammar/items/mod.rs
index 32d0778c4..a285892df 100644
--- a/crates/libsyntax2/src/grammar/items/mod.rs
+++ b/crates/libsyntax2/src/grammar/items/mod.rs
@@ -43,7 +43,12 @@ pub(super) fn item_or_macro(p: &mut Parser, stop_on_r_curly: bool, flavor: ItemF
                 m.abandon(p);
                 if p.at(L_CURLY) {
                     error_block(p, "expected an item");
-                } else if !p.at(EOF) && !(stop_on_r_curly && p.at(R_CURLY)) {
+                } else if p.at(R_CURLY) && !stop_on_r_curly {
+                    let e = p.start();
+                    p.error("unmatched `}`");
+                    p.bump();
+                    e.complete(p, ERROR);
+                } else if !p.at(EOF) && !p.at(R_CURLY) {
                     p.err_and_bump("expected an item");
                 } else {
                     p.error("expected an item");
diff --git a/crates/libsyntax2/src/lib.rs b/crates/libsyntax2/src/lib.rs
index 9ba9970c9..93057dd6a 100644
--- a/crates/libsyntax2/src/lib.rs
+++ b/crates/libsyntax2/src/lib.rs
@@ -127,12 +127,12 @@ fn validate_block_structure(root: SyntaxNodeRef) {
                     assert_eq!(
                         node.parent(),
                         pair.parent(),
-                        "unpaired curleys:\n{}",
+                        "\nunpaired curleys:\n{}",
                         utils::dump_tree(root),
                     );
                     assert!(
                         node.next_sibling().is_none() && pair.prev_sibling().is_none(),
-                        "floating curlys at {:?}\nfile:\n{}\nerror:\n{}\n",
+                        "\nfloating curlys at {:?}\nfile:\n{}\nerror:\n{}\n",
                         node,
                         root.text(),
                         node.text(),
diff --git a/crates/libsyntax2/src/parser_api.rs b/crates/libsyntax2/src/parser_api.rs
index bb34fe973..0a3b29b70 100644
--- a/crates/libsyntax2/src/parser_api.rs
+++ b/crates/libsyntax2/src/parser_api.rs
@@ -141,7 +141,9 @@ impl<'t> Parser<'t> {
     pub(crate) fn err_and_bump(&mut self, message: &str) {
         let m = self.start();
         self.error(message);
-        self.bump();
+        if !self.at(SyntaxKind::L_CURLY) && !self.at(SyntaxKind::R_CURLY) {
+            self.bump();
+        }
         m.complete(self, ERROR);
     }
 }
diff --git a/crates/libsyntax2/tests/data/parser/err/0007_stray_curly_in_file.txt b/crates/libsyntax2/tests/data/parser/err/0007_stray_curly_in_file.txt
index 81e82f7e2..802c69b31 100644
--- a/crates/libsyntax2/tests/data/parser/err/0007_stray_curly_in_file.txt
+++ b/crates/libsyntax2/tests/data/parser/err/0007_stray_curly_in_file.txt
@@ -1,7 +1,7 @@
 ROOT@[0; 31)
   ERROR@[0; 1)
     R_CURLY@[0; 1)
-    err: `expected an item`
+    err: `unmatched `}``
   WHITESPACE@[1; 3)
   STRUCT_DEF@[3; 12)
     STRUCT_KW@[3; 9)
@@ -10,7 +10,7 @@ ROOT@[0; 31)
       IDENT@[10; 11) "S"
     SEMI@[11; 12)
   WHITESPACE@[12; 14)
-  err: `expected an item`
+  err: `unmatched `}``
   ERROR@[14; 15)
     R_CURLY@[14; 15)
   WHITESPACE@[15; 17)
@@ -26,7 +26,7 @@ ROOT@[0; 31)
       L_CURLY@[25; 26)
       R_CURLY@[26; 27)
   WHITESPACE@[27; 29)
-  err: `expected an item`
+  err: `unmatched `}``
   ERROR@[29; 30)
     R_CURLY@[29; 30)
   WHITESPACE@[30; 31)
diff --git a/crates/libsyntax2/tests/data/parser/err/0015_curly_in_params.txt b/crates/libsyntax2/tests/data/parser/err/0015_curly_in_params.txt
index dbc19abea..5f736a978 100644
--- a/crates/libsyntax2/tests/data/parser/err/0015_curly_in_params.txt
+++ b/crates/libsyntax2/tests/data/parser/err/0015_curly_in_params.txt
@@ -9,7 +9,7 @@ ROOT@[0; 14)
       err: `expected value parameter`
       err: `expected R_PAREN`
       err: `expected a block`
-      err: `expected an item`
+      err: `unmatched `}``
   ERROR@[7; 8)
     R_CURLY@[7; 8)
     err: `expected an item`
diff --git a/crates/libsyntax2/tests/data/parser/err/0017_incomplete_binexpr.rs b/crates/libsyntax2/tests/data/parser/err/0017_incomplete_binexpr.rs
new file mode 100644
index 000000000..17bd49777
--- /dev/null
+++ b/crates/libsyntax2/tests/data/parser/err/0017_incomplete_binexpr.rs
@@ -0,0 +1,4 @@
+fn foo(foo: i32) {
+    let bar = 92;
+    1 +
+}
diff --git a/crates/libsyntax2/tests/data/parser/err/0017_incomplete_binexpr.txt b/crates/libsyntax2/tests/data/parser/err/0017_incomplete_binexpr.txt
new file mode 100644
index 000000000..db9a2f175
--- /dev/null
+++ b/crates/libsyntax2/tests/data/parser/err/0017_incomplete_binexpr.txt
@@ -0,0 +1,47 @@
+ROOT@[0; 47)
+  FN_DEF@[0; 46)
+    FN_KW@[0; 2)
+    WHITESPACE@[2; 3)
+    NAME@[3; 6)
+      IDENT@[3; 6) "foo"
+    PARAM_LIST@[6; 16)
+      L_PAREN@[6; 7)
+      PARAM@[7; 15)
+        BIND_PAT@[7; 10)
+          NAME@[7; 10)
+            IDENT@[7; 10) "foo"
+        COLON@[10; 11)
+        WHITESPACE@[11; 12)
+        PATH_TYPE@[12; 15)
+          PATH@[12; 15)
+            PATH_SEGMENT@[12; 15)
+              NAME_REF@[12; 15)
+                IDENT@[12; 15) "i32"
+      R_PAREN@[15; 16)
+    WHITESPACE@[16; 17)
+    BLOCK@[17; 46)
+      L_CURLY@[17; 18)
+      WHITESPACE@[18; 23)
+      LET_STMT@[23; 36)
+        LET_KW@[23; 26)
+        WHITESPACE@[26; 27)
+        BIND_PAT@[27; 30)
+          NAME@[27; 30)
+            IDENT@[27; 30) "bar"
+        WHITESPACE@[30; 31)
+        EQ@[31; 32)
+        WHITESPACE@[32; 33)
+        LITERAL@[33; 35)
+          INT_NUMBER@[33; 35) "92"
+        SEMI@[35; 36)
+      WHITESPACE@[36; 41)
+      BIN_EXPR@[41; 45)
+        LITERAL@[41; 42)
+          INT_NUMBER@[41; 42) "1"
+        WHITESPACE@[42; 43)
+        PLUS@[43; 44)
+        WHITESPACE@[44; 45)
+        err: `expected expression`
+        ERROR@[45; 45)
+      R_CURLY@[45; 46)
+  WHITESPACE@[46; 47)
diff --git a/crates/libsyntax2/tests/test/main.rs b/crates/libsyntax2/tests/test/main.rs
index 596f32216..9958c7ece 100644
--- a/crates/libsyntax2/tests/test/main.rs
+++ b/crates/libsyntax2/tests/test/main.rs
@@ -26,6 +26,7 @@ fn lexer_tests() {
 #[test]
 fn parser_tests() {
     dir_tests(&["parser/inline", "parser/ok", "parser/err"], |text| {
+        eprintln!("\n{}\n", text);
         let file = File::parse(text);
         dump_tree(file.syntax())
     })