17 files changed, 193 insertions, 178 deletions

diff --git a/src/lexer/comments.rs b/src/lexer/comments.rs
index d1e958817..01acb6515 100644
--- a/src/lexer/comments.rs
+++ b/src/lexer/comments.rs
@@ -1,7 +1,6 @@
 use lexer::ptr::Ptr;
 
-use SyntaxKind;
-use syntax_kinds::*;
+use SyntaxKind::{self, *};
 
 pub(crate) fn scan_shebang(ptr: &mut Ptr) -> bool {
     if ptr.next_is('!') && ptr.nnext_is('/') {
diff --git a/src/lexer/mod.rs b/src/lexer/mod.rs
index 65a994327..69cab5b57 100644
--- a/src/lexer/mod.rs
+++ b/src/lexer/mod.rs
@@ -1,21 +1,32 @@
-use {SyntaxKind, Token};
-use syntax_kinds::*;
-
 mod ptr;
-use self::ptr::Ptr;
-
+mod comments;
+mod strings;
+mod numbers;
 mod classes;
-use self::classes::*;
 
-mod numbers;
-use self::numbers::scan_number;
+use {
+    TextUnit,
+    SyntaxKind::{self, *},
+};
 
-mod strings;
-use self::strings::{is_string_literal_start, scan_byte_char_or_string, scan_char, scan_raw_string,
-                    scan_string};
+use self::{
+    ptr::Ptr,
+    classes::*,
+    numbers::scan_number,
+    strings::{
+        is_string_literal_start, scan_byte_char_or_string, scan_char,
+        scan_raw_string, scan_string},
+    comments::{scan_comment, scan_shebang},
+};
 
-mod comments;
-use self::comments::{scan_comment, scan_shebang};
+/// A token of Rust source.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub struct Token {
+    /// The kind of token.
+    pub kind: SyntaxKind,
+    /// The length of the token.
+    pub len: TextUnit,
+}
 
 /// Break a string up into its component tokens
 pub fn tokenize(text: &str) -> Vec<Token> {
@@ -29,6 +40,7 @@ pub fn tokenize(text: &str) -> Vec<Token> {
     }
     acc
 }
+
 /// Get the next token from a string
 pub fn next_token(text: &str) -> Token {
     assert!(!text.is_empty());
@@ -109,7 +121,7 @@ fn next_token_inner(c: char, ptr: &mut Ptr) -> SyntaxKind {
                     DOTDOT
                 }
                 _ => DOT,
-            }
+            };
         }
         ':' => {
             return match ptr.next() {
@@ -118,7 +130,7 @@ fn next_token_inner(c: char, ptr: &mut Ptr) -> SyntaxKind {
                     COLONCOLON
                 }
                 _ => COLON,
-            }
+            };
         }
         '=' => {
             return match ptr.next() {
@@ -131,7 +143,7 @@ fn next_token_inner(c: char, ptr: &mut Ptr) -> SyntaxKind {
                     FAT_ARROW
                 }
                 _ => EQ,
-            }
+            };
         }
         '!' => {
             return match ptr.next() {
@@ -140,7 +152,7 @@ fn next_token_inner(c: char, ptr: &mut Ptr) -> SyntaxKind {
                     NEQ
                 }
                 _ => EXCL,
-            }
+            };
         }
         '-' => {
             return if ptr.next_is('>') {
@@ -148,7 +160,7 @@ fn next_token_inner(c: char, ptr: &mut Ptr) -> SyntaxKind {
                 THIN_ARROW
             } else {
                 MINUS
-            }
+            };
         }
 
         // If the character is an ident start not followed by another single
@@ -202,7 +214,7 @@ fn scan_ident(c: char, ptr: &mut Ptr) -> SyntaxKind {
         return if c == '_' { UNDERSCORE } else { IDENT };
     }
     ptr.bump_while(is_ident_continue);
-    if let Some(kind) = ident_to_keyword(ptr.current_token_text()) {
+    if let Some(kind) = SyntaxKind::from_keyword(ptr.current_token_text()) {
         return kind;
     }
     IDENT
diff --git a/src/lexer/numbers.rs b/src/lexer/numbers.rs
index 95e42246f..38eac9212 100644
--- a/src/lexer/numbers.rs
+++ b/src/lexer/numbers.rs
@@ -1,8 +1,7 @@
 use lexer::ptr::Ptr;
 use lexer::classes::*;
 
-use SyntaxKind;
-use syntax_kinds::*;
+use SyntaxKind::{self, *};
 
 pub(crate) fn scan_number(c: char, ptr: &mut Ptr) -> SyntaxKind {
     if c == '0' {
diff --git a/src/lexer/strings.rs b/src/lexer/strings.rs
index 00a84ec85..e3704fbb3 100644
--- a/src/lexer/strings.rs
+++ b/src/lexer/strings.rs
@@ -1,5 +1,4 @@
-use SyntaxKind;
-use syntax_kinds::*;
+use SyntaxKind::{self, *};
 
 use lexer::ptr::Ptr;
 
diff --git a/src/lib.rs b/src/lib.rs
index 619ad62e5..4260e22e7 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -19,27 +19,36 @@
 extern crate unicode_xid;
 extern crate text_unit;
 
-mod tree;
 mod lexer;
 mod parser;
 mod yellow;
+mod syntax_kinds;
+
+pub use {
+    text_unit::{TextRange, TextUnit},
+    syntax_kinds::SyntaxKind,
+    yellow::{SyntaxNode},
+    lexer::{tokenize, Token},
+};
+
+pub(crate) use {
+    yellow::SyntaxError
+};
+
+pub fn parse(text: String) -> SyntaxNode {
+    let tokens = tokenize(&text);
+    parser::parse::<yellow::GreenBuilder>(text, &tokens)
+}
 
-pub mod syntax_kinds;
-pub use text_unit::{TextRange, TextUnit};
-pub use tree::{SyntaxKind, Token};
-pub(crate) use tree::{Sink, GreenBuilder};
-pub use lexer::{next_token, tokenize};
-pub use yellow::SyntaxNode;
-pub(crate) use yellow::SError;
-pub use parser::{parse_green};
 
 /// Utilities for simple uses of the parser.
 pub mod utils {
-    use std::fmt::Write;
+    use std::{
+        fmt::Write,
+        collections::BTreeSet
+    };
 
-    use {SyntaxNode};
-    use std::collections::BTreeSet;
-    use SError;
+    use {SyntaxNode, SyntaxError};
 
     /// Parse a file and create a string representation of the resulting parse tree.
     pub fn dump_tree_green(syntax: &SyntaxNode) -> String {
@@ -48,7 +57,7 @@ pub mod utils {
         go(syntax, &mut result, 0, &mut errors);
         return result;
 
-        fn go(node: &SyntaxNode, buff: &mut String, level: usize, errors: &mut BTreeSet<SError>) {
+        fn go(node: &SyntaxNode, buff: &mut String, level: usize, errors: &mut BTreeSet<SyntaxError>) {
             buff.push_str(&String::from("  ").repeat(level));
             write!(buff, "{:?}\n", node).unwrap();
             let my_errors: Vec<_> = errors.iter().filter(|e| e.offset == node.range().start())
diff --git a/src/parser/event.rs b/src/parser/event.rs
index 83039c664..a8d503b3d 100644
--- a/src/parser/event.rs
+++ b/src/parser/event.rs
@@ -1,8 +1,29 @@
+//! This module provides a way to construct a `File`.
+//! It is intended to be completely decoupled from the
+//! parser, so as to allow to evolve the tree representation
+//! and the parser algorithm independently.
+//!
+//! The `Sink` trait is the bridge between the parser and the
+//! tree builder: the parser produces a stream of events like
+//! `start node`, `finish node`, and `FileBuilder` converts
+//! this stream to a real tree.
 use {
-    Sink, SyntaxKind, Token,
-    syntax_kinds::TOMBSTONE,
+    TextUnit,
+    SyntaxKind::{self, TOMBSTONE},
+    lexer::Token,
 };
-use super::is_insignificant;
+
+pub(crate) trait Sink {
+    type Tree;
+
+    fn new(text: String) -> Self;
+
+    fn leaf(&mut self, kind: SyntaxKind, len: TextUnit);
+    fn start_internal(&mut self, kind: SyntaxKind);
+    fn finish_internal(&mut self);
+    fn error(&mut self, err: String);
+    fn finish(self) -> Self::Tree;
+}
 
 /// `Parser` produces a flat list of `Event`s.
 /// They are converted to a tree-structure in
@@ -67,7 +88,7 @@ pub(crate) enum Event {
     },
 }
 
-pub(super) fn process(builder: &mut Sink, tokens: &[Token], events: Vec<Event>) {
+pub(super) fn process(builder: &mut impl Sink, tokens: &[Token], events: Vec<Event>) {
     let mut idx = 0;
 
     let mut holes = Vec::new();
@@ -111,7 +132,7 @@ pub(super) fn process(builder: &mut Sink, tokens: &[Token], events: Vec<Event>)
             &Event::Finish => {
                 while idx < tokens.len() {
                     let token = tokens[idx];
-                    if is_insignificant(token.kind) {
+                    if token.kind.is_trivia() {
                         idx += 1;
                         builder.leaf(token.kind, token.len);
                     } else {
@@ -128,7 +149,7 @@ pub(super) fn process(builder: &mut Sink, tokens: &[Token], events: Vec<Event>)
                 // this should be done in a sensible manner instead
                 loop {
                     let token = tokens[idx];
-                    if !is_insignificant(token.kind) {
+                    if !token.kind.is_trivia() {
                         break;
                     }
                     builder.leaf(token.kind, token.len);
diff --git a/src/parser/grammar/mod.rs b/src/parser/grammar/mod.rs
index 23216452f..085e62d56 100644
--- a/src/parser/grammar/mod.rs
+++ b/src/parser/grammar/mod.rs
@@ -21,11 +21,6 @@
 //! After adding a new inline-test, run `cargo collect-tests` to extract
 //! it as a standalone text-fixture into `tests/data/parser/inline`, and
 //! run `cargo test` once to create the "gold" value.
-use parser::parser::Parser;
-use parser::token_set::TokenSet;
-use SyntaxKind;
-use syntax_kinds::*;
-
 mod items;
 mod attributes;
 mod expressions;
@@ -34,6 +29,14 @@ mod patterns;
 mod paths;
 mod type_params;
 
+use {
+    SyntaxKind::{self, *},
+    parser::{
+        parser::Parser,
+        token_set::TokenSet
+    }
+};
+
 pub(crate) fn file(p: &mut Parser) {
     let file = p.start();
     p.eat(SHEBANG);
diff --git a/src/parser/input.rs b/src/parser/input.rs
index 9b400b959..052981fbc 100644
--- a/src/parser/input.rs
+++ b/src/parser/input.rs
@@ -1,6 +1,8 @@
-use {SyntaxKind, TextRange, TextUnit, Token};
-use syntax_kinds::EOF;
-use super::is_insignificant;
+use {
+    SyntaxKind, TextRange, TextUnit,
+    SyntaxKind::EOF,
+    lexer::Token,
+};
 
 use std::ops::{Add, AddAssign};
 
@@ -16,7 +18,7 @@ impl<'t> ParserInput<'t> {
         let mut start_offsets = Vec::new();
         let mut len = 0.into();
         for &token in raw_tokens.iter() {
-            if !is_insignificant(token.kind) {
+            if !token.kind.is_trivia() {
                 tokens.push(token);
                 start_offsets.push(len);
             }
diff --git a/src/parser/mod.rs b/src/parser/mod.rs
index b7d5e5832..e72ab05af 100644
--- a/src/parser/mod.rs
+++ b/src/parser/mod.rs
@@ -5,18 +5,16 @@ mod input;
 mod event;
 mod grammar;
 
-use std::sync::Arc;
 use {
-    Token,
-    yellow::SyntaxNode,
-    syntax_kinds::*
+    lexer::Token,
+    parser::event::{process}
 };
-use GreenBuilder;
-use parser::event::process;
+
+pub(crate) use self::event::Sink;
 
 
 /// Parse a sequence of tokens into the representative node tree
-pub fn parse_green(text: String, tokens: &[Token]) -> SyntaxNode {
+pub(crate) fn parse<S: Sink>(text: String, tokens: &[Token]) -> S::Tree {
     let events = {
         let input = input::ParserInput::new(&text, tokens);
         let parser_impl = parser::imp::ParserImpl::new(&input);
@@ -24,15 +22,7 @@ pub fn parse_green(text: String, tokens: &[Token]) -> SyntaxNode {
         grammar::file(&mut parser);
         parser.0.into_events()
     };
-    let mut builder = GreenBuilder::new(text);
-    process(&mut builder, tokens, events);
-    let (green, errors) = builder.finish();
-    SyntaxNode::new(Arc::new(green), errors)
-}
-
-fn is_insignificant(kind: SyntaxKind) -> bool {
-    match kind {
-        WHITESPACE | COMMENT => true,
-        _ => false,
-    }
+    let mut sink = S::new(text);
+    process(&mut sink, tokens, events);
+    sink.finish()
 }
diff --git a/src/parser/parser/imp.rs b/src/parser/parser/imp.rs
index f2641c388..38237ac06 100644
--- a/src/parser/parser/imp.rs
+++ b/src/parser/parser/imp.rs
@@ -1,8 +1,7 @@
 use parser::input::{InputPosition, ParserInput};
 use parser::event::Event;
 
-use SyntaxKind;
-use syntax_kinds::{EOF, TOMBSTONE};
+use SyntaxKind::{self, EOF, TOMBSTONE};
 
 /// Implementation details of `Parser`, extracted
 /// to a separate struct in order not to pollute
diff --git a/src/parser/parser/mod.rs b/src/parser/parser/mod.rs
index 58f820738..0930ff9e4 100644
--- a/src/parser/parser/mod.rs
+++ b/src/parser/parser/mod.rs
@@ -1,5 +1,4 @@
-use SyntaxKind;
-use syntax_kinds::ERROR;
+use SyntaxKind::{self, ERROR};
 
 pub(super) mod imp;
 use self::imp::ParserImpl;
diff --git a/src/syntax_kinds.rs b/src/syntax_kinds/generated.rs
index 1cc29bb61..d332fd02e 100644
--- a/src/syntax_kinds.rs
+++ b/src/syntax_kinds/generated.rs
@@ -1,7 +1,7 @@
 #![allow(bad_style, missing_docs, unreachable_pub)]
 #![cfg_attr(rustfmt, rustfmt_skip)]
 //! Generated from grammar.ron
-use tree::SyntaxInfo;
+use super::SyntaxInfo;
 
 /// The kind of syntax node, e.g. `IDENT`, `USE_KW`, or `STRUCT_DEF`.
 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
@@ -288,39 +288,39 @@ impl SyntaxKind {
             EOF => &SyntaxInfo { name: "EOF" },
         }
     }
-}
-
-pub(crate) fn ident_to_keyword(ident: &str) -> Option<SyntaxKind> {
-    match ident {
-        "use" => Some(USE_KW),
-        "fn" => Some(FN_KW),
-        "struct" => Some(STRUCT_KW),
-        "enum" => Some(ENUM_KW),
-        "trait" => Some(TRAIT_KW),
-        "impl" => Some(IMPL_KW),
-        "true" => Some(TRUE_KW),
-        "false" => Some(FALSE_KW),
-        "as" => Some(AS_KW),
-        "extern" => Some(EXTERN_KW),
-        "crate" => Some(CRATE_KW),
-        "mod" => Some(MOD_KW),
-        "pub" => Some(PUB_KW),
-        "self" => Some(SELF_KW),
-        "super" => Some(SUPER_KW),
-        "in" => Some(IN_KW),
-        "where" => Some(WHERE_KW),
-        "for" => Some(FOR_KW),
-        "loop" => Some(LOOP_KW),
-        "while" => Some(WHILE_KW),
-        "if" => Some(IF_KW),
-        "match" => Some(MATCH_KW),
-        "const" => Some(CONST_KW),
-        "static" => Some(STATIC_KW),
-        "mut" => Some(MUT_KW),
-        "unsafe" => Some(UNSAFE_KW),
-        "type" => Some(TYPE_KW),
-        "ref" => Some(REF_KW),
-        "let" => Some(LET_KW),
-        _ => None,
+    pub(crate) fn from_keyword(ident: &str) -> Option<SyntaxKind> {
+        match ident {
+            "use" => Some(USE_KW),
+            "fn" => Some(FN_KW),
+            "struct" => Some(STRUCT_KW),
+            "enum" => Some(ENUM_KW),
+            "trait" => Some(TRAIT_KW),
+            "impl" => Some(IMPL_KW),
+            "true" => Some(TRUE_KW),
+            "false" => Some(FALSE_KW),
+            "as" => Some(AS_KW),
+            "extern" => Some(EXTERN_KW),
+            "crate" => Some(CRATE_KW),
+            "mod" => Some(MOD_KW),
+            "pub" => Some(PUB_KW),
+            "self" => Some(SELF_KW),
+            "super" => Some(SUPER_KW),
+            "in" => Some(IN_KW),
+            "where" => Some(WHERE_KW),
+            "for" => Some(FOR_KW),
+            "loop" => Some(LOOP_KW),
+            "while" => Some(WHILE_KW),
+            "if" => Some(IF_KW),
+            "match" => Some(MATCH_KW),
+            "const" => Some(CONST_KW),
+            "static" => Some(STATIC_KW),
+            "mut" => Some(MUT_KW),
+            "unsafe" => Some(UNSAFE_KW),
+            "type" => Some(TYPE_KW),
+            "ref" => Some(REF_KW),
+            "let" => Some(LET_KW),
+            _ => None,
+        }
     }
 }
+
diff --git a/src/syntax_kinds/mod.rs b/src/syntax_kinds/mod.rs
new file mode 100644
index 000000000..a8e9bfe29
--- /dev/null
+++ b/src/syntax_kinds/mod.rs
@@ -0,0 +1,27 @@
+mod generated;
+
+use std::fmt;
+use ::{SyntaxKind::*};
+
+pub use self::generated::SyntaxKind;
+
+impl fmt::Debug for SyntaxKind {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        let name = self.info().name;
+        f.write_str(name)
+    }
+}
+
+pub(crate) struct SyntaxInfo {
+    pub name: &'static str,
+}
+
+
+impl SyntaxKind {
+    pub(crate) fn is_trivia(self: SyntaxKind) -> bool {
+        match self {
+            WHITESPACE | COMMENT | DOC_COMMENT => true,
+            _ => false,
+        }
+    }
+}
diff --git a/src/tree/mod.rs b/src/tree/mod.rs
deleted file mode 100644
index efba82825..000000000
--- a/src/tree/mod.rs
+++ /dev/null
@@ -1,27 +0,0 @@
-mod file_builder;
-
-use ::{TextUnit};
-use std::{fmt};
-pub(crate) use self::file_builder::{Sink, GreenBuilder};
-
-pub use syntax_kinds::SyntaxKind;
-
-impl fmt::Debug for SyntaxKind {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        let name = self.info().name;
-        f.write_str(name)
-    }
-}
-
-pub(crate) struct SyntaxInfo {
-    pub name: &'static str,
-}
-
-/// A token of Rust source.
-#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
-pub struct Token {
-    /// The kind of token.
-    pub kind: SyntaxKind,
-    /// The length of the token.
-    pub len: TextUnit,
-}
diff --git a/src/tree/file_builder.rs b/src/yellow/builder.rs
index f5d1751f9..346d561cd 100644
--- a/src/tree/file_builder.rs
+++ b/src/yellow/builder.rs
@@ -1,36 +1,26 @@
-//! This module provides a way to construct a `File`.
-//! It is intended to be completely decoupled from the
-//! parser, so as to allow to evolve the tree representation
-//! and the parser algorithm independently.
-//!
-//! The `Sink` trait is the bridge between the parser and the
-//! tree builder: the parser produces a stream of events like
-//! `start node`, `finish node`, and `FileBuilder` converts
-//! this stream to a real tree.
 use std::sync::Arc;
 use {
     SyntaxKind, TextRange, TextUnit,
-    yellow::GreenNode
+    yellow::{SyntaxNode, GreenNode, SyntaxError},
+    parser::Sink
 };
-use SError;
-
-pub(crate) trait Sink {
-    fn leaf(&mut self, kind: SyntaxKind, len: TextUnit);
-    fn start_internal(&mut self, kind: SyntaxKind);
-    fn finish_internal(&mut self);
-    fn error(&mut self, err: String);
-}
 
 pub(crate) struct GreenBuilder {
     text: String,
     stack: Vec<GreenNode>,
     pos: TextUnit,
     root: Option<GreenNode>,
-    errors: Vec<SError>,
+    errors: Vec<SyntaxError>,
 }
 
 impl GreenBuilder {
-    pub(crate) fn new(text: String) -> GreenBuilder {
+
+}
+
+impl Sink for GreenBuilder {
+    type Tree = SyntaxNode;
+
+    fn new(text: String) -> Self {
         GreenBuilder {
             text,
             stack: Vec::new(),
@@ -40,12 +30,6 @@ impl GreenBuilder {
         }
     }
 
-    pub(crate) fn finish(self) -> (GreenNode, Vec<SError>) {
-        (self.root.unwrap(), self.errors)
-    }
-}
-
-impl Sink for GreenBuilder {
     fn leaf(&mut self, kind: SyntaxKind, len: TextUnit) {
         let range = TextRange::offset_len(self.pos, len);
         self.pos += len;
@@ -73,15 +57,12 @@ impl Sink for GreenBuilder {
     }
 
     fn error(&mut self, message: String) {
-        self.errors.push(SError { message, offset: self.pos })
+        self.errors.push(SyntaxError { message, offset: self.pos })
     }
-}
-impl SyntaxKind {
-    fn is_trivia(self) -> bool {
-        match self {
-            SyntaxKind::WHITESPACE | SyntaxKind::DOC_COMMENT | SyntaxKind::COMMENT => true,
-            _ => false
-        }
+
+    fn finish(self) -> SyntaxNode {
+        SyntaxNode::new(Arc::new(self.root.unwrap()), self.errors)
     }
 }
 
+
diff --git a/src/yellow/mod.rs b/src/yellow/mod.rs
index 88d88e226..9e64d042f 100644
--- a/src/yellow/mod.rs
+++ b/src/yellow/mod.rs
@@ -1,6 +1,7 @@
 mod green;
 mod red;
 mod syntax;
+mod builder;
 
 use std::{
     sync::{Arc, Weak},
@@ -9,7 +10,8 @@ use std::{
 pub(crate) use self::{
     green::{GreenNode, TextLen},
     red::RedNode,
-    syntax::SError,
+    syntax::SyntaxError,
+    builder::GreenBuilder,
 };
 pub use self::syntax::SyntaxNode;
 
diff --git a/src/yellow/syntax.rs b/src/yellow/syntax.rs
index 7b1a05cd9..78fa5bf95 100644
--- a/src/yellow/syntax.rs
+++ b/src/yellow/syntax.rs
@@ -4,7 +4,8 @@ use std::{
 };
 
 use {
-    TextRange, TextUnit, SyntaxKind,
+    TextRange, TextUnit,
+    SyntaxKind::{self, *},
     yellow::{Ptr, RedNode, GreenNode, TextLen},
 };
 
@@ -18,17 +19,17 @@ pub struct SyntaxNode {
 #[derive(Clone)]
 pub struct SyntaxRoot {
     red: Arc<RedNode>,
-    pub(crate) errors: Arc<Vec<SError>>,
+    pub(crate) errors: Arc<Vec<SyntaxError>>,
 }
 
 #[derive(Debug, Clone, PartialEq, Eq, Hash, Ord, PartialOrd)]
-pub(crate) struct SError {
+pub(crate) struct SyntaxError {
     pub(crate) message: String,
     pub(crate) offset: TextUnit,
 }
 
 impl SyntaxNode {
-    pub(crate) fn new(root: Arc<GreenNode>, errors: Vec<SError>) -> SyntaxNode {
+    pub(crate) fn new(root: Arc<GreenNode>, errors: Vec<SyntaxError>) -> SyntaxNode {
         let root = Arc::new(RedNode::new_root(root));
         let red = Ptr::new(&root);
         let root = SyntaxRoot { red: root, errors: Arc::new(errors) };
@@ -123,7 +124,6 @@ impl fmt::Debug for SyntaxNode {
 }
 
 fn has_short_text(kind: SyntaxKind) -> bool {
-    use syntax_kinds::*;
     match kind {
         IDENT | LIFETIME => true,
         _ => false,