Merge #1570

1570: switch to upstream rowan's API r=matklad a=matklad



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

28 files changed, 238 insertions, 772 deletions

diff --git a/crates/ra_assists/Cargo.toml b/crates/ra_assists/Cargo.toml
index 5ddac1e48..2113286a3 100644
--- a/crates/ra_assists/Cargo.toml
+++ b/crates/ra_assists/Cargo.toml
@@ -5,6 +5,7 @@ version = "0.1.0"
 authors = ["rust-analyzer developers"]
 
 [dependencies]
+format-buf = "1.0.0"
 once_cell = "0.2.0"
 join_to_string = "0.1.3"
 itertools = "0.8.0"
diff --git a/crates/ra_assists/src/add_impl.rs b/crates/ra_assists/src/add_impl.rs
index 59ca88468..4b61f4031 100644
--- a/crates/ra_assists/src/add_impl.rs
+++ b/crates/ra_assists/src/add_impl.rs
@@ -1,5 +1,4 @@
-use std::fmt::Write;
-
+use format_buf::format;
 use hir::db::HirDatabase;
 use join_to_string::join;
 use ra_syntax::{
@@ -19,7 +18,7 @@ pub(crate) fn add_impl(mut ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
         let mut buf = String::new();
         buf.push_str("\n\nimpl");
         if let Some(type_params) = &type_params {
-            write!(buf, "{}", type_params.syntax()).unwrap();
+            format!(buf, "{}", type_params.syntax());
         }
         buf.push_str(" ");
         buf.push_str(name.text().as_str());
diff --git a/crates/ra_assists/src/assist_ctx.rs b/crates/ra_assists/src/assist_ctx.rs
index 4d5a76de6..a12c3ed54 100644
--- a/crates/ra_assists/src/assist_ctx.rs
+++ b/crates/ra_assists/src/assist_ctx.rs
@@ -2,8 +2,9 @@ use hir::db::HirDatabase;
 use ra_db::FileRange;
 use ra_fmt::{leading_indent, reindent};
 use ra_syntax::{
-    algo::{find_covering_element, find_node_at_offset, find_token_at_offset, TokenAtOffset},
+    algo::{find_covering_element, find_node_at_offset},
     AstNode, SourceFile, SyntaxElement, SyntaxNode, SyntaxToken, TextRange, TextUnit,
+    TokenAtOffset,
 };
 use ra_text_edit::TextEditBuilder;
 
@@ -105,7 +106,7 @@ impl<'a, DB: HirDatabase> AssistCtx<'a, DB> {
     }
 
     pub(crate) fn token_at_offset(&self) -> TokenAtOffset<SyntaxToken> {
-        find_token_at_offset(self.source_file.syntax(), self.frange.range.start())
+        self.source_file.syntax().token_at_offset(self.frange.range.start())
     }
 
     pub(crate) fn node_at_offset<N: AstNode>(&self) -> Option<N> {
diff --git a/crates/ra_assists/src/ast_editor.rs b/crates/ra_assists/src/ast_editor.rs
index ab6c347ad..95b871b30 100644
--- a/crates/ra_assists/src/ast_editor.rs
+++ b/crates/ra_assists/src/ast_editor.rs
@@ -4,7 +4,10 @@ use arrayvec::ArrayVec;
 use hir::Name;
 use ra_fmt::leading_indent;
 use ra_syntax::{
-    ast, AstNode, Direction, InsertPosition, SourceFile, SyntaxElement, SyntaxKind::*, T,
+    algo::{insert_children, replace_children},
+    ast, AstNode, Direction, InsertPosition, SourceFile, SyntaxElement,
+    SyntaxKind::*,
+    T,
 };
 use ra_text_edit::TextEditBuilder;
 
@@ -38,7 +41,7 @@ impl<N: AstNode> AstEditor<N> {
         position: InsertPosition<SyntaxElement>,
         to_insert: impl Iterator<Item = SyntaxElement>,
     ) -> N {
-        let new_syntax = self.ast().syntax().insert_children(position, to_insert);
+        let new_syntax = insert_children(self.ast().syntax(), position, to_insert);
         N::cast(new_syntax).unwrap()
     }
 
@@ -48,7 +51,7 @@ impl<N: AstNode> AstEditor<N> {
         to_delete: RangeInclusive<SyntaxElement>,
         to_insert: impl Iterator<Item = SyntaxElement>,
     ) -> N {
-        let new_syntax = self.ast().syntax().replace_children(to_delete, to_insert);
+        let new_syntax = replace_children(self.ast().syntax(), to_delete, to_insert);
         N::cast(new_syntax).unwrap()
     }
 
diff --git a/crates/ra_assists/src/introduce_variable.rs b/crates/ra_assists/src/introduce_variable.rs
index 911de2d48..5eb708310 100644
--- a/crates/ra_assists/src/introduce_variable.rs
+++ b/crates/ra_assists/src/introduce_variable.rs
@@ -1,5 +1,4 @@
-use std::fmt::Write;
-
+use format_buf::format;
 use hir::db::HirDatabase;
 use ra_syntax::{
     ast::{self, AstNode},
@@ -37,7 +36,7 @@ pub(crate) fn introduce_variable(mut ctx: AssistCtx<impl HirDatabase>) -> Option
             buf.push_str("let var_name = ");
             TextUnit::of_str("let ")
         };
-        write!(buf, "{}", expr.syntax()).unwrap();
+        format!(buf, "{}", expr.syntax());
         let full_stmt = ast::ExprStmt::cast(anchor_stmt.clone());
         let is_full_stmt = if let Some(expr_stmt) = &full_stmt {
             Some(expr.syntax().clone()) == expr_stmt.expr().map(|e| e.syntax().clone())
diff --git a/crates/ra_assists/src/move_guard.rs b/crates/ra_assists/src/move_guard.rs
index 0f3cdbe53..127c9e068 100644
--- a/crates/ra_assists/src/move_guard.rs
+++ b/crates/ra_assists/src/move_guard.rs
@@ -2,7 +2,7 @@ use hir::db::HirDatabase;
 use ra_syntax::{
     ast,
     ast::{AstNode, AstToken, IfExpr, MatchArm},
-    SyntaxElement, TextUnit,
+    TextUnit,
 };
 
 use crate::{Assist, AssistCtx, AssistId};
@@ -18,10 +18,10 @@ pub(crate) fn move_guard_to_arm_body(mut ctx: AssistCtx<impl HirDatabase>) -> Op
 
     ctx.add_action(AssistId("move_guard_to_arm_body"), "move guard to arm body", |edit| {
         edit.target(guard.syntax().text_range());
-        let offseting_amount = match &space_before_guard {
-            Some(SyntaxElement::Token(tok)) => {
+        let offseting_amount = match space_before_guard.and_then(|it| it.into_token()) {
+            Some(tok) => {
                 if let Some(_) = ast::Whitespace::cast(tok.clone()) {
-                    let ele = space_before_guard.unwrap().text_range();
+                    let ele = tok.text_range();
                     edit.delete(ele);
                     ele.len()
                 } else {
diff --git a/crates/ra_hir/src/ty/tests.rs b/crates/ra_hir/src/ty/tests.rs
index 706500484..676711d0a 100644
--- a/crates/ra_hir/src/ty/tests.rs
+++ b/crates/ra_hir/src/ty/tests.rs
@@ -3211,8 +3211,7 @@ fn typing_whitespace_inside_a_function_should_not_invalidate_types() {
     );
     {
         let file = db.parse(pos.file_id).ok().unwrap();
-        let node =
-            algo::find_token_at_offset(file.syntax(), pos.offset).right_biased().unwrap().parent();
+        let node = file.syntax().token_at_offset(pos.offset).right_biased().unwrap().parent();
         let events = db.log_executed(|| {
             SourceAnalyzer::new(&db, pos.file_id, &node, None);
         });
@@ -3232,8 +3231,7 @@ fn typing_whitespace_inside_a_function_should_not_invalidate_types() {
 
     {
         let file = db.parse(pos.file_id).ok().unwrap();
-        let node =
-            algo::find_token_at_offset(file.syntax(), pos.offset).right_biased().unwrap().parent();
+        let node = file.syntax().token_at_offset(pos.offset).right_biased().unwrap().parent();
         let events = db.log_executed(|| {
             SourceAnalyzer::new(&db, pos.file_id, &node, None);
         });
diff --git a/crates/ra_ide_api/Cargo.toml b/crates/ra_ide_api/Cargo.toml
index c49a05de1..78a3db14d 100644
--- a/crates/ra_ide_api/Cargo.toml
+++ b/crates/ra_ide_api/Cargo.toml
@@ -5,6 +5,7 @@ version = "0.1.0"
 authors = ["rust-analyzer developers"]
 
 [dependencies]
+format-buf = "1.0.0"
 itertools = "0.8.0"
 join_to_string = "0.1.3"
 log = "0.4.5"
diff --git a/crates/ra_ide_api/src/completion/completion_context.rs b/crates/ra_ide_api/src/completion/completion_context.rs
index 6fee7b5be..dfaa9ce69 100644
--- a/crates/ra_ide_api/src/completion/completion_context.rs
+++ b/crates/ra_ide_api/src/completion/completion_context.rs
@@ -1,6 +1,6 @@
 use hir::source_binder;
 use ra_syntax::{
-    algo::{find_covering_element, find_node_at_offset, find_token_at_offset},
+    algo::{find_covering_element, find_node_at_offset},
     ast, AstNode, Parse, SourceFile,
     SyntaxKind::*,
     SyntaxNode, SyntaxToken, TextRange, TextUnit,
@@ -49,7 +49,7 @@ impl<'a> CompletionContext<'a> {
     ) -> Option<CompletionContext<'a>> {
         let module = source_binder::module_from_position(db, position);
         let token =
-            find_token_at_offset(original_parse.tree().syntax(), position.offset).left_biased()?;
+            original_parse.tree().syntax().token_at_offset(position.offset).left_biased()?;
         let analyzer =
             hir::SourceAnalyzer::new(db, position.file_id, &token.parent(), Some(position.offset));
         let mut ctx = CompletionContext {
diff --git a/crates/ra_ide_api/src/display/short_label.rs b/crates/ra_ide_api/src/display/short_label.rs
index be499e485..825a033ee 100644
--- a/crates/ra_ide_api/src/display/short_label.rs
+++ b/crates/ra_ide_api/src/display/short_label.rs
@@ -1,5 +1,4 @@
-use std::fmt::Write;
-
+use format_buf::format;
 use ra_syntax::ast::{self, AstNode, NameOwner, TypeAscriptionOwner, VisibilityOwner};
 
 pub(crate) trait ShortLabel {
@@ -73,7 +72,7 @@ where
     let mut buf = short_label_from_node(node, prefix)?;
 
     if let Some(type_ref) = node.ascribed_type() {
-        write!(buf, ": {}", type_ref.syntax()).unwrap();
+        format!(buf, ": {}", type_ref.syntax());
     }
 
     Some(buf)
diff --git a/crates/ra_ide_api/src/extend_selection.rs b/crates/ra_ide_api/src/extend_selection.rs
index 140820df6..edbf622c1 100644
--- a/crates/ra_ide_api/src/extend_selection.rs
+++ b/crates/ra_ide_api/src/extend_selection.rs
@@ -1,10 +1,10 @@
 use ra_db::SourceDatabase;
 use ra_syntax::{
-    algo::{find_covering_element, find_token_at_offset, TokenAtOffset},
+    algo::find_covering_element,
     ast::{self, AstNode, AstToken},
-    Direction, SyntaxElement,
+    Direction, NodeOrToken,
     SyntaxKind::*,
-    SyntaxNode, SyntaxToken, TextRange, TextUnit, T,
+    SyntaxNode, SyntaxToken, TextRange, TextUnit, TokenAtOffset, T,
 };
 
 use crate::{db::RootDatabase, FileRange};
@@ -34,7 +34,7 @@ fn try_extend_selection(root: &SyntaxNode, range: TextRange) -> Option<TextRange
 
     if range.is_empty() {
         let offset = range.start();
-        let mut leaves = find_token_at_offset(root, offset);
+        let mut leaves = root.token_at_offset(offset);
         if leaves.clone().all(|it| it.kind() == WHITESPACE) {
             return Some(extend_ws(root, leaves.next()?, offset));
         }
@@ -53,7 +53,7 @@ fn try_extend_selection(root: &SyntaxNode, range: TextRange) -> Option<TextRange
         return Some(leaf_range);
     };
     let node = match find_covering_element(root, range) {
-        SyntaxElement::Token(token) => {
+        NodeOrToken::Token(token) => {
             if token.text_range() != range {
                 return Some(token.text_range());
             }
@@ -64,7 +64,7 @@ fn try_extend_selection(root: &SyntaxNode, range: TextRange) -> Option<TextRange
             }
             token.parent()
         }
-        SyntaxElement::Node(node) => node,
+        NodeOrToken::Node(node) => node,
     };
     if node.text_range() != range {
         return Some(node.text_range());
@@ -153,8 +153,8 @@ fn extend_list_item(node: &SyntaxNode) -> Option<TextRange> {
         node.siblings_with_tokens(dir)
             .skip(1)
             .skip_while(|node| match node {
-                SyntaxElement::Node(_) => false,
-                SyntaxElement::Token(it) => is_single_line_ws(it),
+                NodeOrToken::Node(_) => false,
+                NodeOrToken::Token(it) => is_single_line_ws(it),
             })
             .next()
             .and_then(|it| it.into_token())
diff --git a/crates/ra_ide_api/src/folding_ranges.rs b/crates/ra_ide_api/src/folding_ranges.rs
index 571d1c595..e60ae8cf6 100644
--- a/crates/ra_ide_api/src/folding_ranges.rs
+++ b/crates/ra_ide_api/src/folding_ranges.rs
@@ -2,7 +2,7 @@ use rustc_hash::FxHashSet;
 
 use ra_syntax::{
     ast::{self, AstNode, AstToken, VisibilityOwner},
-    Direction, SourceFile, SyntaxElement,
+    Direction, NodeOrToken, SourceFile,
     SyntaxKind::{self, *},
     SyntaxNode, TextRange,
 };
@@ -31,8 +31,8 @@ pub(crate) fn folding_ranges(file: &SourceFile) -> Vec<Fold> {
         // Fold items that span multiple lines
         if let Some(kind) = fold_kind(element.kind()) {
             let is_multiline = match &element {
-                SyntaxElement::Node(node) => node.text().contains_char('\n'),
-                SyntaxElement::Token(token) => token.text().contains('\n'),
+                NodeOrToken::Node(node) => node.text().contains_char('\n'),
+                NodeOrToken::Token(token) => token.text().contains('\n'),
             };
             if is_multiline {
                 res.push(Fold { range: element.text_range(), kind });
@@ -41,7 +41,7 @@ pub(crate) fn folding_ranges(file: &SourceFile) -> Vec<Fold> {
         }
 
         match element {
-            SyntaxElement::Token(token) => {
+            NodeOrToken::Token(token) => {
                 // Fold groups of comments
                 if let Some(comment) = ast::Comment::cast(token) {
                     if !visited_comments.contains(&comment) {
@@ -53,7 +53,7 @@ pub(crate) fn folding_ranges(file: &SourceFile) -> Vec<Fold> {
                     }
                 }
             }
-            SyntaxElement::Node(node) => {
+            NodeOrToken::Node(node) => {
                 // Fold groups of imports
                 if node.kind() == USE_ITEM && !visited_imports.contains(&node) {
                     if let Some(range) = contiguous_range_for_group(&node, &mut visited_imports) {
@@ -108,7 +108,7 @@ fn contiguous_range_for_group_unless(
     let mut last = first.clone();
     for element in first.siblings_with_tokens(Direction::Next) {
         let node = match element {
-            SyntaxElement::Token(token) => {
+            NodeOrToken::Token(token) => {
                 if let Some(ws) = ast::Whitespace::cast(token) {
                     if !ws.spans_multiple_lines() {
                         // Ignore whitespace without blank lines
@@ -119,7 +119,7 @@ fn contiguous_range_for_group_unless(
                 // group ends here
                 break;
             }
-            SyntaxElement::Node(node) => node,
+            NodeOrToken::Node(node) => node,
         };
 
         // Stop if we find a node that doesn't belong to the group
@@ -154,7 +154,7 @@ fn contiguous_range_for_comment(
     let mut last = first.clone();
     for element in first.syntax().siblings_with_tokens(Direction::Next) {
         match element {
-            SyntaxElement::Token(token) => {
+            NodeOrToken::Token(token) => {
                 if let Some(ws) = ast::Whitespace::cast(token.clone()) {
                     if !ws.spans_multiple_lines() {
                         // Ignore whitespace without blank lines
@@ -173,7 +173,7 @@ fn contiguous_range_for_comment(
                 // * A comment of a different flavor was reached
                 break;
             }
-            SyntaxElement::Node(_) => break,
+            NodeOrToken::Node(_) => break,
         };
     }
 
diff --git a/crates/ra_ide_api/src/goto_type_definition.rs b/crates/ra_ide_api/src/goto_type_definition.rs
index 007259d9e..72884e5ca 100644
--- a/crates/ra_ide_api/src/goto_type_definition.rs
+++ b/crates/ra_ide_api/src/goto_type_definition.rs
@@ -1,5 +1,5 @@
 use ra_db::SourceDatabase;
-use ra_syntax::{algo::find_token_at_offset, ast, AstNode};
+use ra_syntax::{ast, AstNode};
 
 use crate::{db::RootDatabase, FilePosition, NavigationTarget, RangeInfo};
 
@@ -9,7 +9,7 @@ pub(crate) fn goto_type_definition(
 ) -> Option<RangeInfo<Vec<NavigationTarget>>> {
     let parse = db.parse(position.file_id);
 
-    let node = find_token_at_offset(parse.tree().syntax(), position.offset).find_map(|token| {
+    let node = parse.tree().syntax().token_at_offset(position.offset).find_map(|token| {
         token
             .parent()
             .ancestors()
diff --git a/crates/ra_ide_api/src/join_lines.rs b/crates/ra_ide_api/src/join_lines.rs
index 7f25f2108..a2e4b6f3c 100644
--- a/crates/ra_ide_api/src/join_lines.rs
+++ b/crates/ra_ide_api/src/join_lines.rs
@@ -3,7 +3,7 @@ use ra_fmt::{compute_ws, extract_trivial_expression};
 use ra_syntax::{
     algo::{find_covering_element, non_trivia_sibling},
     ast::{self, AstNode, AstToken},
-    Direction, SourceFile, SyntaxElement,
+    Direction, NodeOrToken, SourceFile,
     SyntaxKind::{self, WHITESPACE},
     SyntaxNode, SyntaxToken, TextRange, TextUnit, T,
 };
@@ -23,8 +23,8 @@ pub fn join_lines(file: &SourceFile, range: TextRange) -> TextEdit {
     };
 
     let node = match find_covering_element(file.syntax(), range) {
-        SyntaxElement::Node(node) => node,
-        SyntaxElement::Token(token) => token.parent(),
+        NodeOrToken::Node(node) => node,
+        NodeOrToken::Token(token) => token.parent(),
     };
     let mut edit = TextEditBuilder::default();
     for token in node.descendants_with_tokens().filter_map(|it| it.into_token()) {
diff --git a/crates/ra_ide_api/src/matching_brace.rs b/crates/ra_ide_api/src/matching_brace.rs
index 1e2fac848..e802d01e4 100644
--- a/crates/ra_ide_api/src/matching_brace.rs
+++ b/crates/ra_ide_api/src/matching_brace.rs
@@ -1,9 +1,11 @@
-use ra_syntax::{algo::find_token_at_offset, ast::AstNode, SourceFile, SyntaxKind, TextUnit, T};
+use ra_syntax::{ast::AstNode, SourceFile, SyntaxKind, TextUnit, T};
 
 pub fn matching_brace(file: &SourceFile, offset: TextUnit) -> Option<TextUnit> {
     const BRACES: &[SyntaxKind] =
         &[T!['{'], T!['}'], T!['['], T![']'], T!['('], T![')'], T![<], T![>]];
-    let (brace_node, brace_idx) = find_token_at_offset(file.syntax(), offset)
+    let (brace_node, brace_idx) = file
+        .syntax()
+        .token_at_offset(offset)
         .filter_map(|node| {
             let idx = BRACES.iter().position(|&brace| brace == node.kind())?;
             Some((node, idx))
diff --git a/crates/ra_ide_api/src/syntax_tree.rs b/crates/ra_ide_api/src/syntax_tree.rs
index 76c50f6d6..a07e670fa 100644
--- a/crates/ra_ide_api/src/syntax_tree.rs
+++ b/crates/ra_ide_api/src/syntax_tree.rs
@@ -1,7 +1,7 @@
 use crate::db::RootDatabase;

 use ra_db::SourceDatabase;

 use ra_syntax::{

-    algo, AstNode, SourceFile, SyntaxElement,

+    algo, AstNode, NodeOrToken, SourceFile,

     SyntaxKind::{RAW_STRING, STRING},

     SyntaxToken, TextRange,

 };

@@ -16,8 +16,8 @@ pub(crate) fn syntax_tree(
     let parse = db.parse(file_id);

     if let Some(text_range) = text_range {

         let node = match algo::find_covering_element(parse.tree().syntax(), text_range) {

-            SyntaxElement::Node(node) => node,

-            SyntaxElement::Token(token) => {

+            NodeOrToken::Node(node) => node,

+            NodeOrToken::Token(token) => {

                 if let Some(tree) = syntax_tree_for_string(&token, text_range) {

                     return tree;

                 }

diff --git a/crates/ra_ide_api/src/typing.rs b/crates/ra_ide_api/src/typing.rs
index 5a1cbcc49..6b3fd5904 100644
--- a/crates/ra_ide_api/src/typing.rs
+++ b/crates/ra_ide_api/src/typing.rs
@@ -1,11 +1,11 @@
 use ra_db::{FilePosition, SourceDatabase};
 use ra_fmt::leading_indent;
 use ra_syntax::{
-    algo::{find_node_at_offset, find_token_at_offset, TokenAtOffset},
+    algo::find_node_at_offset,
     ast::{self, AstToken},
     AstNode, SmolStr, SourceFile,
     SyntaxKind::*,
-    SyntaxToken, TextRange, TextUnit,
+    SyntaxToken, TextRange, TextUnit, TokenAtOffset,
 };
 use ra_text_edit::{TextEdit, TextEditBuilder};
 
@@ -14,7 +14,9 @@ use crate::{db::RootDatabase, SourceChange, SourceFileEdit};
 pub(crate) fn on_enter(db: &RootDatabase, position: FilePosition) -> Option<SourceChange> {
     let parse = db.parse(position.file_id);
     let file = parse.tree();
-    let comment = find_token_at_offset(file.syntax(), position.offset)
+    let comment = file
+        .syntax()
+        .token_at_offset(position.offset)
         .left_biased()
         .and_then(ast::Comment::cast)?;
 
@@ -45,7 +47,7 @@ pub(crate) fn on_enter(db: &RootDatabase, position: FilePosition) -> Option<Sour
 }
 
 fn node_indent(file: &SourceFile, token: &SyntaxToken) -> Option<SmolStr> {
-    let ws = match find_token_at_offset(file.syntax(), token.text_range().start()) {
+    let ws = match file.syntax().token_at_offset(token.text_range().start()) {
         TokenAtOffset::Between(l, r) => {
             assert!(r == *token);
             l
@@ -91,7 +93,10 @@ pub(crate) fn on_dot_typed(db: &RootDatabase, position: FilePosition) -> Option<
     let parse = db.parse(position.file_id);
     assert_eq!(parse.tree().syntax().text().char_at(position.offset), Some('.'));
 
-    let whitespace = find_token_at_offset(parse.tree().syntax(), position.offset)
+    let whitespace = parse
+        .tree()
+        .syntax()
+        .token_at_offset(position.offset)
         .left_biased()
         .and_then(ast::Whitespace::cast)?;
 
diff --git a/crates/ra_mbe/src/syntax_bridge.rs b/crates/ra_mbe/src/syntax_bridge.rs
index 7ff0fc472..8225759e7 100644
--- a/crates/ra_mbe/src/syntax_bridge.rs
+++ b/crates/ra_mbe/src/syntax_bridge.rs
@@ -1,12 +1,13 @@
-use crate::subtree_source::SubtreeTokenSource;
-use crate::ExpandError;
 use ra_parser::{ParseError, TreeSink};
 use ra_syntax::{
-    ast, AstNode, AstToken, Parse, SmolStr, SyntaxElement, SyntaxKind, SyntaxKind::*, SyntaxNode,
+    ast, AstNode, AstToken, NodeOrToken, Parse, SmolStr, SyntaxKind, SyntaxKind::*, SyntaxNode,
     SyntaxTreeBuilder, TextRange, TextUnit, T,
 };
 use tt::buffer::{Cursor, TokenBuffer};
 
+use crate::subtree_source::SubtreeTokenSource;
+use crate::ExpandError;
+
 /// Maps `tt::TokenId` to the relative range of the original token.
 #[derive(Default)]
 pub struct TokenMap {
@@ -200,7 +201,7 @@ fn convert_tt(
         }
 
         match child {
-            SyntaxElement::Token(token) => {
+            NodeOrToken::Token(token) => {
                 if let Some(doc_tokens) = convert_doc_comment(&token) {
                     token_trees.extend(doc_tokens);
                 } else if token.kind().is_trivia() {
@@ -210,7 +211,7 @@ fn convert_tt(
                     let char = token.text().chars().next().unwrap();
 
                     let spacing = match child_iter.peek() {
-                        Some(SyntaxElement::Token(token)) => {
+                        Some(NodeOrToken::Token(token)) => {
                             if token.kind().is_punct() {
                                 tt::Spacing::Joint
                             } else {
@@ -241,7 +242,7 @@ fn convert_tt(
                     token_trees.push(child);
                 }
             }
-            SyntaxElement::Node(node) => {
+            NodeOrToken::Node(node) => {
                 let child = convert_tt(token_map, global_offset, &node)?.into();
                 token_trees.push(child);
             }
diff --git a/crates/ra_mbe/src/tests.rs b/crates/ra_mbe/src/tests.rs
index 9151b6ecd..192e9007d 100644
--- a/crates/ra_mbe/src/tests.rs
+++ b/crates/ra_mbe/src/tests.rs
@@ -1,4 +1,4 @@
-use ra_syntax::{ast, AstNode};
+use ra_syntax::{ast, AstNode, NodeOrToken};
 
 use super::*;
 
@@ -118,11 +118,11 @@ pub fn debug_dump_ignore_spaces(node: &ra_syntax::SyntaxNode) -> String {
         match event {
             WalkEvent::Enter(element) => {
                 match element {
-                    ra_syntax::SyntaxElement::Node(node) => {
+                    NodeOrToken::Node(node) => {
                         indent!();
                         writeln!(buf, "{:?}", node.kind()).unwrap();
                     }
-                    ra_syntax::SyntaxElement::Token(token) => match token.kind() {
+                    NodeOrToken::Token(token) => match token.kind() {
                         ra_syntax::SyntaxKind::WHITESPACE => {}
                         _ => {
                             indent!();
diff --git a/crates/ra_syntax/Cargo.toml b/crates/ra_syntax/Cargo.toml
index a5565de33..97b6b047f 100644
--- a/crates/ra_syntax/Cargo.toml
+++ b/crates/ra_syntax/Cargo.toml
@@ -10,7 +10,7 @@ repository = "https://github.com/rust-analyzer/rust-analyzer"
 [dependencies]
 unicode-xid = "0.1.0"
 itertools = "0.8.0"
-rowan = "0.5.6"
+rowan = "0.6.0-pre.1"
 
 # ideally, `serde` should be enabled by `ra_lsp_server`, but we enable it here
 # to reduce number of compilations
diff --git a/crates/ra_syntax/src/algo.rs b/crates/ra_syntax/src/algo.rs
index f47e11e66..45f624810 100644
--- a/crates/ra_syntax/src/algo.rs
+++ b/crates/ra_syntax/src/algo.rs
@@ -1,18 +1,12 @@
 pub mod visit;
 
-use itertools::Itertools;
-
-use crate::{AstNode, Direction, SyntaxElement, SyntaxNode, SyntaxToken, TextRange, TextUnit};
+use std::ops::RangeInclusive;
 
-pub use rowan::TokenAtOffset;
+use itertools::Itertools;
 
-pub fn find_token_at_offset(node: &SyntaxNode, offset: TextUnit) -> TokenAtOffset<SyntaxToken> {
-    match node.0.token_at_offset(offset) {
-        TokenAtOffset::None => TokenAtOffset::None,
-        TokenAtOffset::Single(n) => TokenAtOffset::Single(SyntaxToken(n)),
-        TokenAtOffset::Between(l, r) => TokenAtOffset::Between(SyntaxToken(l), SyntaxToken(r)),
-    }
-}
+use crate::{
+    AstNode, Direction, NodeOrToken, SyntaxElement, SyntaxNode, SyntaxNodePtr, TextRange, TextUnit,
+};
 
 /// Returns ancestors of the node at the offset, sorted by length. This should
 /// do the right thing at an edge, e.g. when searching for expressions at `{
@@ -23,7 +17,7 @@ pub fn ancestors_at_offset(
     node: &SyntaxNode,
     offset: TextUnit,
 ) -> impl Iterator<Item = SyntaxNode> {
-    find_token_at_offset(node, offset)
+    node.token_at_offset(offset)
         .map(|token| token.parent().ancestors())
         .kmerge_by(|node1, node2| node1.text_range().len() < node2.text_range().len())
 }
@@ -44,20 +38,118 @@ pub fn find_node_at_offset<N: AstNode>(syntax: &SyntaxNode, offset: TextUnit) ->
 /// Finds the first sibling in the given direction which is not `trivia`
 pub fn non_trivia_sibling(element: SyntaxElement, direction: Direction) -> Option<SyntaxElement> {
     return match element {
-        SyntaxElement::Node(node) => node.siblings_with_tokens(direction).skip(1).find(not_trivia),
-        SyntaxElement::Token(token) => {
-            token.siblings_with_tokens(direction).skip(1).find(not_trivia)
-        }
+        NodeOrToken::Node(node) => node.siblings_with_tokens(direction).skip(1).find(not_trivia),
+        NodeOrToken::Token(token) => token.siblings_with_tokens(direction).skip(1).find(not_trivia),
     };
 
     fn not_trivia(element: &SyntaxElement) -> bool {
         match element {
-            SyntaxElement::Node(_) => true,
-            SyntaxElement::Token(token) => !token.kind().is_trivia(),
+            NodeOrToken::Node(_) => true,
+            NodeOrToken::Token(token) => !token.kind().is_trivia(),
         }
     }
 }
 
 pub fn find_covering_element(root: &SyntaxNode, range: TextRange) -> SyntaxElement {
-    SyntaxElement::new(root.0.covering_node(range))
+    root.covering_element(range)
+}
+
+#[derive(Debug, PartialEq, Eq, Clone, Copy)]
+pub enum InsertPosition<T> {
+    First,
+    Last,
+    Before(T),
+    After(T),
+}
+
+/// Adds specified children (tokens or nodes) to the current node at the
+/// specific position.
+///
+/// This is a type-unsafe low-level editing API, if you need to use it,
+/// prefer to create a type-safe abstraction on top of it instead.
+pub fn insert_children(
+    parent: &SyntaxNode,
+    position: InsertPosition<SyntaxElement>,
+    to_insert: impl Iterator<Item = SyntaxElement>,
+) -> SyntaxNode {
+    let mut delta = TextUnit::default();
+    let to_insert = to_insert.map(|element| {
+        delta += element.text_range().len();
+        to_green_element(element)
+    });
+
+    let old_children = parent.green().children();
+
+    let new_children = match &position {
+        InsertPosition::First => {
+            to_insert.chain(old_children.iter().cloned()).collect::<Box<[_]>>()
+        }
+        InsertPosition::Last => old_children.iter().cloned().chain(to_insert).collect::<Box<[_]>>(),
+        InsertPosition::Before(anchor) | InsertPosition::After(anchor) => {
+            let take_anchor = if let InsertPosition::After(_) = position { 1 } else { 0 };
+            let split_at = position_of_child(parent, anchor.clone()) + take_anchor;
+            let (before, after) = old_children.split_at(split_at);
+            before
+                .iter()
+                .cloned()
+                .chain(to_insert)
+                .chain(after.iter().cloned())
+                .collect::<Box<[_]>>()
+        }
+    };
+
+    with_children(parent, new_children)
+}
+
+/// Replaces all nodes in `to_delete` with nodes from `to_insert`
+///
+/// This is a type-unsafe low-level editing API, if you need to use it,
+/// prefer to create a type-safe abstraction on top of it instead.
+pub fn replace_children(
+    parent: &SyntaxNode,
+    to_delete: RangeInclusive<SyntaxElement>,
+    to_insert: impl Iterator<Item = SyntaxElement>,
+) -> SyntaxNode {
+    let start = position_of_child(parent, to_delete.start().clone());
+    let end = position_of_child(parent, to_delete.end().clone());
+    let old_children = parent.green().children();
+
+    let new_children = old_children[..start]
+        .iter()
+        .cloned()
+        .chain(to_insert.map(to_green_element))
+        .chain(old_children[end + 1..].iter().cloned())
+        .collect::<Box<[_]>>();
+    with_children(parent, new_children)
+}
+
+fn with_children(
+    parent: &SyntaxNode,
+    new_children: Box<[NodeOrToken<rowan::GreenNode, rowan::GreenToken>]>,
+) -> SyntaxNode {
+    let len = new_children.iter().map(|it| it.text_len()).sum::<TextUnit>();
+    let new_node =
+        rowan::GreenNode::new(rowan::cursor::SyntaxKind(parent.kind() as u16), new_children);
+    let new_root_node = parent.replace_with(new_node);
+    let new_root_node = SyntaxNode::new_root(new_root_node);
+
+    // FIXME: use a more elegant way to re-fetch the node (#1185), make
+    // `range` private afterwards
+    let mut ptr = SyntaxNodePtr::new(parent);
+    ptr.range = TextRange::offset_len(ptr.range().start(), len);
+    ptr.to_node(&new_root_node)
+}
+
+fn position_of_child(parent: &SyntaxNode, child: SyntaxElement) -> usize {
+    parent
+        .children_with_tokens()
+        .position(|it| it == child)
+        .expect("element is not a child of current element")
+}
+
+fn to_green_element(element: SyntaxElement) -> NodeOrToken<rowan::GreenNode, rowan::GreenToken> {
+    match element {
+        NodeOrToken::Node(it) => it.green().clone().into(),
+        NodeOrToken::Token(it) => it.green().clone().into(),
+    }
 }
diff --git a/crates/ra_syntax/src/ast/expr_extensions.rs b/crates/ra_syntax/src/ast/expr_extensions.rs
index 139bd3ec0..f9190d877 100644
--- a/crates/ra_syntax/src/ast/expr_extensions.rs
+++ b/crates/ra_syntax/src/ast/expr_extensions.rs
@@ -2,7 +2,7 @@
 
 use crate::{
     ast::{self, child_opt, children, AstChildren, AstNode},
-    SmolStr, SyntaxElement,
+    SmolStr,
     SyntaxKind::*,
     SyntaxToken, T,
 };
@@ -229,14 +229,11 @@ pub enum LiteralKind {
 
 impl ast::Literal {
     pub fn token(&self) -> SyntaxToken {
-        let elem = self
-            .syntax()
+        self.syntax()
             .children_with_tokens()
-            .find(|e| e.kind() != ATTR && !e.kind().is_trivia());
-        match elem {
-            Some(SyntaxElement::Token(token)) => token,
-            _ => unreachable!(),
-        }
+            .find(|e| e.kind() != ATTR && !e.kind().is_trivia())
+            .and_then(|e| e.into_token())
+            .unwrap()
     }
 
     pub fn kind(&self) -> LiteralKind {
diff --git a/crates/ra_syntax/src/ast/extensions.rs b/crates/ra_syntax/src/ast/extensions.rs
index 753fc42c6..d4873b39a 100644
--- a/crates/ra_syntax/src/ast/extensions.rs
+++ b/crates/ra_syntax/src/ast/extensions.rs
@@ -24,10 +24,7 @@ impl ast::NameRef {
 }
 
 fn text_of_first_token(node: &SyntaxNode) -> &SmolStr {
-    match node.0.green().children().first() {
-        Some(rowan::GreenElement::Token(it)) => it.text(),
-        _ => panic!(),
-    }
+    node.green().children().first().and_then(|it| it.as_token()).unwrap().text()
 }
 
 impl ast::Attr {
diff --git a/crates/ra_syntax/src/lib.rs b/crates/ra_syntax/src/lib.rs
index 8af04c136..7f69b86e1 100644
--- a/crates/ra_syntax/src/lib.rs
+++ b/crates/ra_syntax/src/lib.rs
@@ -20,7 +20,6 @@
 //! [Swift]: <https://github.com/apple/swift/blob/13d593df6f359d0cb2fc81cfaac273297c539455/lib/Syntax/README.md>
 
 mod syntax_node;
-mod syntax_text;
 mod syntax_error;
 mod parsing;
 mod validation;
@@ -38,19 +37,17 @@ use ra_text_edit::AtomTextEdit;
 use crate::syntax_node::GreenNode;
 
 pub use crate::{
+    algo::InsertPosition,
     ast::{AstNode, AstToken},
     parsing::{classify_literal, tokenize, Token},
     ptr::{AstPtr, SyntaxNodePtr},
     syntax_error::{Location, SyntaxError, SyntaxErrorKind},
     syntax_node::{
-        Direction, InsertPosition, SyntaxElement, SyntaxNode, SyntaxToken, SyntaxTreeBuilder,
-        WalkEvent,
+        Direction, NodeOrToken, SyntaxElement, SyntaxNode, SyntaxToken, SyntaxTreeBuilder,
     },
-    syntax_text::SyntaxText,
 };
-pub use ra_parser::SyntaxKind;
-pub use ra_parser::T;
-pub use rowan::{SmolStr, TextRange, TextUnit};
+pub use ra_parser::{SyntaxKind, T};
+pub use rowan::{SmolStr, SyntaxText, TextRange, TextUnit, TokenAtOffset, WalkEvent};
 
 /// `Parse` is the result of the parsing: a syntax tree and a collection of
 /// errors.
@@ -76,7 +73,7 @@ impl<T> Parse<T> {
     }
 
     pub fn syntax_node(&self) -> SyntaxNode {
-        SyntaxNode::new(self.green.clone())
+        SyntaxNode::new_root(self.green.clone())
     }
 }
 
@@ -146,18 +143,17 @@ impl Parse<SourceFile> {
 pub use crate::ast::SourceFile;
 
 impl SourceFile {
-    fn new(green: GreenNode) -> SourceFile {
-        let root = SyntaxNode::new(green);
+    pub fn parse(text: &str) -> Parse<SourceFile> {
+        let (green, mut errors) = parsing::parse_text(text);
+        let root = SyntaxNode::new_root(green.clone());
+
         if cfg!(debug_assertions) {
             validation::validate_block_structure(&root);
         }
-        assert_eq!(root.kind(), SyntaxKind::SOURCE_FILE);
-        SourceFile::cast(root).unwrap()
-    }
 
-    pub fn parse(text: &str) -> Parse<SourceFile> {
-        let (green, mut errors) = parsing::parse_text(text);
-        errors.extend(validation::validate(&SourceFile::new(green.clone())));
+        errors.extend(validation::validate(&root));
+
+        assert_eq!(root.kind(), SyntaxKind::SOURCE_FILE);
         Parse { green, errors: Arc::new(errors), _ty: PhantomData }
     }
 }
@@ -267,8 +263,8 @@ fn api_walkthrough() {
         match event {
             WalkEvent::Enter(node) => {
                 let text = match &node {
-                    SyntaxElement::Node(it) => it.text().to_string(),
-                    SyntaxElement::Token(it) => it.text().to_string(),
+                    NodeOrToken::Node(it) => it.text().to_string(),
+                    NodeOrToken::Token(it) => it.text().to_string(),
                 };
                 buf += &format!("{:indent$}{:?} {:?}\n", " ", text, node.kind(), indent = indent);
                 indent += 2;
diff --git a/crates/ra_syntax/src/parsing/reparsing.rs b/crates/ra_syntax/src/parsing/reparsing.rs
index 2f388bdfe..65b8aa10d 100644
--- a/crates/ra_syntax/src/parsing/reparsing.rs
+++ b/crates/ra_syntax/src/parsing/reparsing.rs
@@ -16,7 +16,7 @@ use crate::{
         text_token_source::TextTokenSource,
         text_tree_sink::TextTreeSink,
     },
-    syntax_node::{GreenNode, GreenToken, SyntaxElement, SyntaxNode},
+    syntax_node::{GreenNode, GreenToken, NodeOrToken, SyntaxElement, SyntaxNode},
     SyntaxError,
     SyntaxKind::*,
     TextRange, TextUnit, T,
@@ -70,7 +70,8 @@ fn reparse_token<'node>(
                 }
             }
 
-            let new_token = GreenToken::new(rowan::SyntaxKind(token.kind().into()), text.into());
+            let new_token =
+                GreenToken::new(rowan::cursor::SyntaxKind(token.kind().into()), text.into());
             Some((token.replace_with(new_token), token.text_range()))
         }
         _ => None,
@@ -98,8 +99,8 @@ fn get_text_after_edit(element: SyntaxElement, edit: &AtomTextEdit) -> String {
     let edit =
         AtomTextEdit::replace(edit.delete - element.text_range().start(), edit.insert.clone());
     let text = match element {
-        SyntaxElement::Token(token) => token.text().to_string(),
-        SyntaxElement::Node(node) => node.text().to_string(),
+        NodeOrToken::Token(token) => token.text().to_string(),
+        NodeOrToken::Node(node) => node.text().to_string(),
     };
     edit.apply(text)
 }
@@ -114,8 +115,8 @@ fn is_contextual_kw(text: &str) -> bool {
 fn find_reparsable_node(node: &SyntaxNode, range: TextRange) -> Option<(SyntaxNode, Reparser)> {
     let node = algo::find_covering_element(node, range);
     let mut ancestors = match node {
-        SyntaxElement::Token(it) => it.parent().ancestors(),
-        SyntaxElement::Node(it) => it.ancestors(),
+        NodeOrToken::Token(it) => it.parent().ancestors(),
+        NodeOrToken::Node(it) => it.ancestors(),
     };
     ancestors.find_map(|node| {
         let first_child = node.first_child_or_token().map(|it| it.kind());
diff --git a/crates/ra_syntax/src/syntax_node.rs b/crates/ra_syntax/src/syntax_node.rs
index c42045d77..b2f5b8c64 100644
--- a/crates/ra_syntax/src/syntax_node.rs
+++ b/crates/ra_syntax/src/syntax_node.rs
@@ -6,487 +6,37 @@
 //! The *real* implementation is in the (language-agnostic) `rowan` crate, this
 //! modules just wraps its API.
 
-use std::{fmt, iter::successors, ops::RangeInclusive};
-
 use ra_parser::ParseError;
-use rowan::GreenNodeBuilder;
+use rowan::{GreenNodeBuilder, Language};
 
 use crate::{
     syntax_error::{SyntaxError, SyntaxErrorKind},
-    AstNode, Parse, SmolStr, SourceFile, SyntaxKind, SyntaxNodePtr, SyntaxText, TextRange,
-    TextUnit,
+    Parse, SmolStr, SyntaxKind, TextUnit,
 };
 
-pub use rowan::WalkEvent;
 pub(crate) use rowan::{GreenNode, GreenToken};
 
-#[derive(Debug, PartialEq, Eq, Clone, Copy)]
-pub enum InsertPosition<T> {
-    First,
-    Last,
-    Before(T),
-    After(T),
-}
-
-#[derive(PartialEq, Eq, Hash, Clone)]
-pub struct SyntaxNode(pub(crate) rowan::cursor::SyntaxNode);
+#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub enum RustLanguage {}
+impl Language for RustLanguage {
+    type Kind = SyntaxKind;
 
-impl fmt::Debug for SyntaxNode {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        if f.alternate() {
-            let mut level = 0;
-            for event in self.preorder_with_tokens() {
-                match event {
-                    WalkEvent::Enter(element) => {
-                        for _ in 0..level {
-                            write!(f, "  ")?;
-                        }
-                        match element {
-                            SyntaxElement::Node(node) => writeln!(f, "{:?}", node)?,
-                            SyntaxElement::Token(token) => writeln!(f, "{:?}", token)?,
-                        }
-                        level += 1;
-                    }
-                    WalkEvent::Leave(_) => level -= 1,
-                }
-            }
-            assert_eq!(level, 0);
-            Ok(())
-        } else {
-            write!(f, "{:?}@{:?}", self.kind(), self.text_range())
-        }
+    fn kind_from_raw(raw: rowan::cursor::SyntaxKind) -> SyntaxKind {
+        SyntaxKind::from(raw.0)
     }
-}
 
-impl fmt::Display for SyntaxNode {
-    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
-        fmt::Display::fmt(&self.text(), fmt)
+    fn kind_to_raw(kind: SyntaxKind) -> rowan::cursor::SyntaxKind {
+        rowan::cursor::SyntaxKind(kind.into())
     }
 }
 
-#[derive(Debug, Clone, Copy, PartialEq, Eq)]
-pub enum Direction {
-    Next,
-    Prev,
-}
-
-impl SyntaxNode {
-    pub(crate) fn new(green: GreenNode) -> SyntaxNode {
-        let inner = rowan::cursor::SyntaxNode::new_root(green);
-        SyntaxNode(inner)
-    }
-
-    pub fn kind(&self) -> SyntaxKind {
-        self.0.kind().0.into()
-    }
-
-    pub fn text_range(&self) -> TextRange {
-        self.0.text_range()
-    }
-
-    pub fn text(&self) -> SyntaxText {
-        SyntaxText::new(self.clone())
-    }
-
-    pub fn parent(&self) -> Option<SyntaxNode> {
-        self.0.parent().map(SyntaxNode)
-    }
-
-    pub fn first_child(&self) -> Option<SyntaxNode> {
-        self.0.first_child().map(SyntaxNode)
-    }
-
-    pub fn first_child_or_token(&self) -> Option<SyntaxElement> {
-        self.0.first_child_or_token().map(SyntaxElement::new)
-    }
-
-    pub fn last_child(&self) -> Option<SyntaxNode> {
-        self.0.last_child().map(SyntaxNode)
-    }
-
-    pub fn last_child_or_token(&self) -> Option<SyntaxElement> {
-        self.0.last_child_or_token().map(SyntaxElement::new)
-    }
-
-    pub fn next_sibling(&self) -> Option<SyntaxNode> {
-        self.0.next_sibling().map(SyntaxNode)
-    }
-
-    pub fn next_sibling_or_token(&self) -> Option<SyntaxElement> {
-        self.0.next_sibling_or_token().map(SyntaxElement::new)
-    }
-
-    pub fn prev_sibling(&self) -> Option<SyntaxNode> {
-        self.0.prev_sibling().map(SyntaxNode)
-    }
-
-    pub fn prev_sibling_or_token(&self) -> Option<SyntaxElement> {
-        self.0.prev_sibling_or_token().map(SyntaxElement::new)
-    }
-
-    pub fn children(&self) -> SyntaxNodeChildren {
-        SyntaxNodeChildren(self.0.children())
-    }
-
-    pub fn children_with_tokens(&self) -> SyntaxElementChildren {
-        SyntaxElementChildren(self.0.children_with_tokens())
-    }
-
-    pub fn first_token(&self) -> Option<SyntaxToken> {
-        self.0.first_token().map(SyntaxToken)
-    }
-
-    pub fn last_token(&self) -> Option<SyntaxToken> {
-        self.0.last_token().map(SyntaxToken)
-    }
+pub type SyntaxNode = rowan::SyntaxNode<RustLanguage>;
+pub type SyntaxToken = rowan::SyntaxToken<RustLanguage>;
+pub type SyntaxElement = rowan::NodeOrToken<SyntaxNode, SyntaxToken>;
+pub type SyntaxNodeChildren = rowan::SyntaxNodeChildren<RustLanguage>;
+pub type SyntaxElementChildren = rowan::SyntaxElementChildren<RustLanguage>;
 
-    pub fn ancestors(&self) -> impl Iterator<Item = SyntaxNode> {
-        successors(Some(self.clone()), |node| node.parent())
-    }
-
-    pub fn descendants(&self) -> impl Iterator<Item = SyntaxNode> {
-        self.preorder().filter_map(|event| match event {
-            WalkEvent::Enter(node) => Some(node),
-            WalkEvent::Leave(_) => None,
-        })
-    }
-
-    pub fn descendants_with_tokens(&self) -> impl Iterator<Item = SyntaxElement> {
-        self.preorder_with_tokens().filter_map(|event| match event {
-            WalkEvent::Enter(it) => Some(it),
-            WalkEvent::Leave(_) => None,
-        })
-    }
-
-    pub fn siblings(&self, direction: Direction) -> impl Iterator<Item = SyntaxNode> {
-        successors(Some(self.clone()), move |node| match direction {
-            Direction::Next => node.next_sibling(),
-            Direction::Prev => node.prev_sibling(),
-        })
-    }
-
-    pub fn siblings_with_tokens(
-        &self,
-        direction: Direction,
-    ) -> impl Iterator<Item = SyntaxElement> {
-        let me: SyntaxElement = self.clone().into();
-        successors(Some(me), move |el| match direction {
-            Direction::Next => el.next_sibling_or_token(),
-            Direction::Prev => el.prev_sibling_or_token(),
-        })
-    }
-
-    pub fn preorder(&self) -> impl Iterator<Item = WalkEvent<SyntaxNode>> {
-        self.0.preorder().map(|event| match event {
-            WalkEvent::Enter(n) => WalkEvent::Enter(SyntaxNode(n)),
-            WalkEvent::Leave(n) => WalkEvent::Leave(SyntaxNode(n)),
-        })
-    }
-
-    pub fn preorder_with_tokens(&self) -> impl Iterator<Item = WalkEvent<SyntaxElement>> {
-        self.0.preorder_with_tokens().map(|event| match event {
-            WalkEvent::Enter(n) => WalkEvent::Enter(SyntaxElement::new(n)),
-            WalkEvent::Leave(n) => WalkEvent::Leave(SyntaxElement::new(n)),
-        })
-    }
-
-    pub(crate) fn replace_with(&self, replacement: GreenNode) -> GreenNode {
-        self.0.replace_with(replacement)
-    }
-
-    /// Adds specified children (tokens or nodes) to the current node at the
-    /// specific position.
-    ///
-    /// This is a type-unsafe low-level editing API, if you need to use it,
-    /// prefer to create a type-safe abstraction on top of it instead.
-    pub fn insert_children(
-        &self,
-        position: InsertPosition<SyntaxElement>,
-        to_insert: impl Iterator<Item = SyntaxElement>,
-    ) -> SyntaxNode {
-        let mut delta = TextUnit::default();
-        let to_insert = to_insert.map(|element| {
-            delta += element.text_len();
-            to_green_element(element)
-        });
-
-        let old_children = self.0.green().children();
-
-        let new_children = match &position {
-            InsertPosition::First => {
-                to_insert.chain(old_children.iter().cloned()).collect::<Box<[_]>>()
-            }
-            InsertPosition::Last => {
-                old_children.iter().cloned().chain(to_insert).collect::<Box<[_]>>()
-            }
-            InsertPosition::Before(anchor) | InsertPosition::After(anchor) => {
-                let take_anchor = if let InsertPosition::After(_) = position { 1 } else { 0 };
-                let split_at = self.position_of_child(anchor.clone()) + take_anchor;
-                let (before, after) = old_children.split_at(split_at);
-                before
-                    .iter()
-                    .cloned()
-                    .chain(to_insert)
-                    .chain(after.iter().cloned())
-                    .collect::<Box<[_]>>()
-            }
-        };
-
-        self.with_children(new_children)
-    }
-
-    /// Replaces all nodes in `to_delete` with nodes from `to_insert`
-    ///
-    /// This is a type-unsafe low-level editing API, if you need to use it,
-    /// prefer to create a type-safe abstraction on top of it instead.
-    pub fn replace_children(
-        &self,
-        to_delete: RangeInclusive<SyntaxElement>,
-        to_insert: impl Iterator<Item = SyntaxElement>,
-    ) -> SyntaxNode {
-        let start = self.position_of_child(to_delete.start().clone());
-        let end = self.position_of_child(to_delete.end().clone());
-        let old_children = self.0.green().children();
-
-        let new_children = old_children[..start]
-            .iter()
-            .cloned()
-            .chain(to_insert.map(to_green_element))
-            .chain(old_children[end + 1..].iter().cloned())
-            .collect::<Box<[_]>>();
-        self.with_children(new_children)
-    }
-
-    fn with_children(&self, new_children: Box<[rowan::GreenElement]>) -> SyntaxNode {
-        let len = new_children.iter().map(|it| it.text_len()).sum::<TextUnit>();
-        let new_node = GreenNode::new(rowan::SyntaxKind(self.kind() as u16), new_children);
-        let new_file_node = self.replace_with(new_node);
-        let file = SourceFile::new(new_file_node);
-
-        // FIXME: use a more elegant way to re-fetch the node (#1185), make
-        // `range` private afterwards
-        let mut ptr = SyntaxNodePtr::new(self);
-        ptr.range = TextRange::offset_len(ptr.range().start(), len);
-        ptr.to_node(file.syntax()).to_owned()
-    }
-
-    fn position_of_child(&self, child: SyntaxElement) -> usize {
-        self.children_with_tokens()
-            .position(|it| it == child)
-            .expect("element is not a child of current element")
-    }
-}
-
-fn to_green_element(element: SyntaxElement) -> rowan::GreenElement {
-    match element {
-        SyntaxElement::Node(node) => node.0.green().clone().into(),
-        SyntaxElement::Token(tok) => {
-            GreenToken::new(rowan::SyntaxKind(tok.kind() as u16), tok.text().clone()).into()
-        }
-    }
-}
-
-#[derive(Clone, PartialEq, Eq, Hash)]
-pub struct SyntaxToken(pub(crate) rowan::cursor::SyntaxToken);
-
-impl fmt::Debug for SyntaxToken {
-    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
-        write!(fmt, "{:?}@{:?}", self.kind(), self.text_range())?;
-        if self.text().len() < 25 {
-            return write!(fmt, " {:?}", self.text());
-        }
-        let text = self.text().as_str();
-        for idx in 21..25 {
-            if text.is_char_boundary(idx) {
-                let text = format!("{} ...", &text[..idx]);
-                return write!(fmt, " {:?}", text);
-            }
-        }
-        unreachable!()
-    }
-}
-
-impl fmt::Display for SyntaxToken {
-    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
-        fmt::Display::fmt(self.text(), fmt)
-    }
-}
-
-impl SyntaxToken {
-    pub fn kind(&self) -> SyntaxKind {
-        self.0.kind().0.into()
-    }
-
-    pub fn text(&self) -> &SmolStr {
-        self.0.text()
-    }
-
-    pub fn text_range(&self) -> TextRange {
-        self.0.text_range()
-    }
-
-    pub fn parent(&self) -> SyntaxNode {
-        SyntaxNode(self.0.parent())
-    }
-
-    pub fn next_sibling_or_token(&self) -> Option<SyntaxElement> {
-        self.0.next_sibling_or_token().map(SyntaxElement::new)
-    }
-
-    pub fn prev_sibling_or_token(&self) -> Option<SyntaxElement> {
-        self.0.prev_sibling_or_token().map(SyntaxElement::new)
-    }
-
-    pub fn siblings_with_tokens(
-        &self,
-        direction: Direction,
-    ) -> impl Iterator<Item = SyntaxElement> {
-        let me: SyntaxElement = self.clone().into();
-        successors(Some(me), move |el| match direction {
-            Direction::Next => el.next_sibling_or_token(),
-            Direction::Prev => el.prev_sibling_or_token(),
-        })
-    }
-
-    pub fn next_token(&self) -> Option<SyntaxToken> {
-        self.0.next_token().map(SyntaxToken)
-    }
-
-    pub fn prev_token(&self) -> Option<SyntaxToken> {
-        self.0.prev_token().map(SyntaxToken)
-    }
-
-    pub(crate) fn replace_with(&self, new_token: GreenToken) -> GreenNode {
-        self.0.replace_with(new_token)
-    }
-}
-
-#[derive(Debug, PartialEq, Eq, Hash, Clone)]
-pub enum SyntaxElement {
-    Node(SyntaxNode),
-    Token(SyntaxToken),
-}
-
-impl From<SyntaxNode> for SyntaxElement {
-    fn from(node: SyntaxNode) -> Self {
-        SyntaxElement::Node(node)
-    }
-}
-
-impl From<SyntaxToken> for SyntaxElement {
-    fn from(token: SyntaxToken) -> Self {
-        SyntaxElement::Token(token)
-    }
-}
-
-impl fmt::Display for SyntaxElement {
-    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
-        match self {
-            SyntaxElement::Node(it) => fmt::Display::fmt(it, fmt),
-            SyntaxElement::Token(it) => fmt::Display::fmt(it, fmt),
-        }
-    }
-}
-
-impl SyntaxElement {
-    pub(crate) fn new(el: rowan::cursor::SyntaxElement) -> Self {
-        match el {
-            rowan::cursor::SyntaxElement::Node(it) => SyntaxElement::Node(SyntaxNode(it)),
-            rowan::cursor::SyntaxElement::Token(it) => SyntaxElement::Token(SyntaxToken(it)),
-        }
-    }
-
-    pub fn kind(&self) -> SyntaxKind {
-        match self {
-            SyntaxElement::Node(it) => it.kind(),
-            SyntaxElement::Token(it) => it.kind(),
-        }
-    }
-
-    pub fn as_node(&self) -> Option<&SyntaxNode> {
-        match self {
-            SyntaxElement::Node(node) => Some(node),
-            SyntaxElement::Token(_) => None,
-        }
-    }
-
-    pub fn into_node(self) -> Option<SyntaxNode> {
-        match self {
-            SyntaxElement::Node(node) => Some(node),
-            SyntaxElement::Token(_) => None,
-        }
-    }
-
-    pub fn as_token(&self) -> Option<&SyntaxToken> {
-        match self {
-            SyntaxElement::Node(_) => None,
-            SyntaxElement::Token(token) => Some(token),
-        }
-    }
-
-    pub fn into_token(self) -> Option<SyntaxToken> {
-        match self {
-            SyntaxElement::Node(_) => None,
-            SyntaxElement::Token(token) => Some(token),
-        }
-    }
-
-    pub fn next_sibling_or_token(&self) -> Option<SyntaxElement> {
-        match self {
-            SyntaxElement::Node(it) => it.next_sibling_or_token(),
-            SyntaxElement::Token(it) => it.next_sibling_or_token(),
-        }
-    }
-
-    pub fn prev_sibling_or_token(&self) -> Option<SyntaxElement> {
-        match self {
-            SyntaxElement::Node(it) => it.prev_sibling_or_token(),
-            SyntaxElement::Token(it) => it.prev_sibling_or_token(),
-        }
-    }
-
-    pub fn ancestors(&self) -> impl Iterator<Item = SyntaxNode> {
-        match self {
-            SyntaxElement::Node(it) => it.clone(),
-            SyntaxElement::Token(it) => it.parent(),
-        }
-        .ancestors()
-    }
-
-    pub fn text_range(&self) -> TextRange {
-        match self {
-            SyntaxElement::Node(it) => it.text_range(),
-            SyntaxElement::Token(it) => it.text_range(),
-        }
-    }
-
-    fn text_len(&self) -> TextUnit {
-        match self {
-            SyntaxElement::Node(node) => node.0.green().text_len(),
-            SyntaxElement::Token(token) => TextUnit::of_str(token.0.text()),
-        }
-    }
-}
-
-#[derive(Clone, Debug)]
-pub struct SyntaxNodeChildren(rowan::cursor::SyntaxNodeChildren);
-
-impl Iterator for SyntaxNodeChildren {
-    type Item = SyntaxNode;
-    fn next(&mut self) -> Option<SyntaxNode> {
-        self.0.next().map(SyntaxNode)
-    }
-}
-
-#[derive(Clone, Debug)]
-pub struct SyntaxElementChildren(rowan::cursor::SyntaxElementChildren);
-
-impl Iterator for SyntaxElementChildren {
-    type Item = SyntaxElement;
-    fn next(&mut self) -> Option<SyntaxElement> {
-        self.0.next().map(SyntaxElement::new)
-    }
-}
+pub use rowan::{Direction, NodeOrToken};
 
 pub struct SyntaxTreeBuilder {
     errors: Vec<SyntaxError>,
@@ -507,19 +57,21 @@ impl SyntaxTreeBuilder {
 
     pub fn finish(self) -> Parse<SyntaxNode> {
         let (green, errors) = self.finish_raw();
-        let node = SyntaxNode::new(green);
+        let node = SyntaxNode::new_root(green);
         if cfg!(debug_assertions) {
             crate::validation::validate_block_structure(&node);
         }
-        Parse::new(node.0.green().clone(), errors)
+        Parse::new(node.green().clone(), errors)
     }
 
     pub fn token(&mut self, kind: SyntaxKind, text: SmolStr) {
-        self.inner.token(rowan::SyntaxKind(kind.into()), text)
+        let kind = RustLanguage::kind_to_raw(kind);
+        self.inner.token(kind, text)
     }
 
     pub fn start_node(&mut self, kind: SyntaxKind) {
-        self.inner.start_node(rowan::SyntaxKind(kind.into()))
+        let kind = RustLanguage::kind_to_raw(kind);
+        self.inner.start_node(kind)
     }
 
     pub fn finish_node(&mut self) {
diff --git a/crates/ra_syntax/src/syntax_text.rs b/crates/ra_syntax/src/syntax_text.rs
deleted file mode 100644
index 652cb7a1e..000000000
--- a/crates/ra_syntax/src/syntax_text.rs
+++ /dev/null
@@ -1,178 +0,0 @@
-use std::{
-    fmt,
-    ops::{self, Bound},
-};
-
-use crate::{SmolStr, SyntaxElement, SyntaxNode, TextRange, TextUnit};
-
-#[derive(Clone)]
-pub struct SyntaxText {
-    node: SyntaxNode,
-    range: TextRange,
-}
-
-impl SyntaxText {
-    pub(crate) fn new(node: SyntaxNode) -> SyntaxText {
-        let range = node.text_range();
-        SyntaxText { node, range }
-    }
-
-    pub fn try_fold_chunks<T, F, E>(&self, init: T, mut f: F) -> Result<T, E>
-    where
-        F: FnMut(T, &str) -> Result<T, E>,
-    {
-        self.node.descendants_with_tokens().try_fold(init, move |acc, element| {
-            let res = match element {
-                SyntaxElement::Token(token) => {
-                    let range = match self.range.intersection(&token.text_range()) {
-                        None => return Ok(acc),
-                        Some(it) => it,
-                    };
-                    let slice = if range == token.text_range() {
-                        token.text()
-                    } else {
-                        let range = range - token.text_range().start();
-                        &token.text()[range]
-                    };
-                    f(acc, slice)?
-                }
-                SyntaxElement::Node(_) => acc,
-            };
-            Ok(res)
-        })
-    }
-
-    pub fn try_for_each_chunk<F: FnMut(&str) -> Result<(), E>, E>(
-        &self,
-        mut f: F,
-    ) -> Result<(), E> {
-        self.try_fold_chunks((), move |(), chunk| f(chunk))
-    }
-
-    pub fn for_each_chunk<F: FnMut(&str)>(&self, mut f: F) {
-        enum Void {}
-        match self.try_for_each_chunk(|chunk| Ok::<(), Void>(f(chunk))) {
-            Ok(()) => (),
-            Err(void) => match void {},
-        }
-    }
-
-    pub fn to_smol_string(&self) -> SmolStr {
-        self.to_string().into()
-    }
-
-    pub fn contains_char(&self, c: char) -> bool {
-        self.try_for_each_chunk(|chunk| if chunk.contains(c) { Err(()) } else { Ok(()) }).is_err()
-    }
-
-    pub fn find_char(&self, c: char) -> Option<TextUnit> {
-        let mut acc: TextUnit = 0.into();
-        let res = self.try_for_each_chunk(|chunk| {
-            if let Some(pos) = chunk.find(c) {
-                let pos: TextUnit = (pos as u32).into();
-                return Err(acc + pos);
-            }
-            acc += TextUnit::of_str(chunk);
-            Ok(())
-        });
-        found(res)
-    }
-
-    pub fn len(&self) -> TextUnit {
-        self.range.len()
-    }
-
-    pub fn is_empty(&self) -> bool {
-        self.range.is_empty()
-    }
-
-    pub fn slice(&self, range: impl ops::RangeBounds<TextUnit>) -> SyntaxText {
-        let start = match range.start_bound() {
-            Bound::Included(&b) => b,
-            Bound::Excluded(_) => panic!("utf-aware slicing can't work this way"),
-            Bound::Unbounded => 0.into(),
-        };
-        let end = match range.end_bound() {
-            Bound::Included(_) => panic!("utf-aware slicing can't work this way"),
-            Bound::Excluded(&b) => b,
-            Bound::Unbounded => self.len(),
-        };
-        assert!(start <= end);
-        let len = end - start;
-        let start = self.range.start() + start;
-        let end = start + len;
-        assert!(
-            start <= end,
-            "invalid slice, range: {:?}, slice: {:?}",
-            self.range,
-            (range.start_bound(), range.end_bound()),
-        );
-        let range = TextRange::from_to(start, end);
-        assert!(
-            range.is_subrange(&self.range),
-            "invalid slice, range: {:?}, slice: {:?}",
-            self.range,
-            range,
-        );
-        SyntaxText { node: self.node.clone(), range }
-    }
-
-    pub fn char_at(&self, offset: impl Into<TextUnit>) -> Option<char> {
-        let offset = offset.into();
-        let mut start: TextUnit = 0.into();
-        let res = self.try_for_each_chunk(|chunk| {
-            let end = start + TextUnit::of_str(chunk);
-            if start <= offset && offset < end {
-                let off: usize = u32::from(offset - start) as usize;
-                return Err(chunk[off..].chars().next().unwrap());
-            }
-            start = end;
-            Ok(())
-        });
-        found(res)
-    }
-}
-
-fn found<T>(res: Result<(), T>) -> Option<T> {
-    match res {
-        Ok(()) => None,
-        Err(it) => Some(it),
-    }
-}
-
-impl fmt::Debug for SyntaxText {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        fmt::Debug::fmt(&self.to_string(), f)
-    }
-}
-
-impl fmt::Display for SyntaxText {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        self.try_for_each_chunk(|chunk| fmt::Display::fmt(chunk, f))
-    }
-}
-
-impl From<SyntaxText> for String {
-    fn from(text: SyntaxText) -> String {
-        text.to_string()
-    }
-}
-
-impl PartialEq<str> for SyntaxText {
-    fn eq(&self, mut rhs: &str) -> bool {
-        self.try_for_each_chunk(|chunk| {
-            if !rhs.starts_with(chunk) {
-                return Err(());
-            }
-            rhs = &rhs[chunk.len()..];
-            Ok(())
-        })
-        .is_ok()
-    }
-}
-
-impl PartialEq<&'_ str> for SyntaxText {
-    fn eq(&self, rhs: &&str) -> bool {
-        self == *rhs
-    }
-}
diff --git a/crates/ra_syntax/src/validation.rs b/crates/ra_syntax/src/validation.rs
index 19bdafef2..e03c02d1b 100644
--- a/crates/ra_syntax/src/validation.rs
+++ b/crates/ra_syntax/src/validation.rs
@@ -5,16 +5,16 @@ mod field_expr;
 
 use crate::{
     algo::visit::{visitor_ctx, VisitorCtx},
-    ast, AstNode, SourceFile, SyntaxError,
+    ast, SyntaxError,
     SyntaxKind::{BYTE, BYTE_STRING, CHAR, STRING},
     SyntaxNode, TextUnit, T,
 };
 
 pub(crate) use unescape::EscapeError;
 
-pub(crate) fn validate(file: &SourceFile) -> Vec<SyntaxError> {
+pub(crate) fn validate(root: &SyntaxNode) -> Vec<SyntaxError> {
     let mut errors = Vec::new();
-    for node in file.syntax().descendants() {
+    for node in root.descendants() {
         let _ = visitor_ctx(&mut errors)
             .visit::<ast::Literal, _>(validate_literal)
             .visit::<ast::Block, _>(block::validate_block_node)