5 files changed, 110 insertions, 132 deletions

diff --git a/crates/mbe/src/mbe_expander/matcher.rs b/crates/mbe/src/mbe_expander/matcher.rs
index 385b46601..fdc8844ce 100644
--- a/crates/mbe/src/mbe_expander/matcher.rs
+++ b/crates/mbe/src/mbe_expander/matcher.rs
@@ -150,7 +150,7 @@ fn match_subtree(
                     res.add_err(err!("leftover tokens"));
                 }
             }
-            Op::Var { name, kind, .. } => {
+            Op::Var { name, kind } => {
                 let kind = match kind {
                     Some(k) => k,
                     None => {
@@ -309,7 +309,7 @@ impl<'a> TtIter<'a> {
             }
         }
 
-        let buffer = TokenBuffer::new(&self.inner.as_slice());
+        let buffer = TokenBuffer::from_tokens(&self.inner.as_slice());
         let mut src = SubtreeTokenSource::new(&buffer);
         let mut sink = OffsetTokenSink { cursor: buffer.begin(), error: false };
 
@@ -336,11 +336,11 @@ impl<'a> TtIter<'a> {
             err = Some(err!("no tokens consumed"));
         }
         let res = match res.len() {
-            1 => Some(res[0].clone()),
+            1 => Some(res[0].cloned()),
             0 => None,
             _ => Some(tt::TokenTree::Subtree(tt::Subtree {
                 delimiter: None,
-                token_trees: res.into_iter().cloned().collect(),
+                token_trees: res.into_iter().map(|it| it.cloned()).collect(),
             })),
         };
         ExpandResult { value: res, err }
diff --git a/crates/mbe/src/mbe_expander/transcriber.rs b/crates/mbe/src/mbe_expander/transcriber.rs
index 57f3f104d..720531237 100644
--- a/crates/mbe/src/mbe_expander/transcriber.rs
+++ b/crates/mbe/src/mbe_expander/transcriber.rs
@@ -100,8 +100,8 @@ fn expand_subtree(
                 err = err.or(e);
                 arena.push(tt.into());
             }
-            Op::Var { name, id, .. } => {
-                let ExpandResult { value: fragment, err: e } = expand_var(ctx, &name, *id);
+            Op::Var { name, .. } => {
+                let ExpandResult { value: fragment, err: e } = expand_var(ctx, &name);
                 err = err.or(e);
                 push_fragment(arena, fragment);
             }
@@ -118,10 +118,12 @@ fn expand_subtree(
     ExpandResult { value: tt::Subtree { delimiter: template.delimiter, token_trees: tts }, err }
 }
 
-fn expand_var(ctx: &mut ExpandCtx, v: &SmolStr, id: tt::TokenId) -> ExpandResult<Fragment> {
+fn expand_var(ctx: &mut ExpandCtx, v: &SmolStr) -> ExpandResult<Fragment> {
     if v == "crate" {
         // We simply produce identifier `$crate` here. And it will be resolved when lowering ast to Path.
-        let tt = tt::Leaf::from(tt::Ident { text: "$crate".into(), id }).into();
+        let tt =
+            tt::Leaf::from(tt::Ident { text: "$crate".into(), id: tt::TokenId::unspecified() })
+                .into();
         ExpandResult::ok(Fragment::Tokens(tt))
     } else if !ctx.bindings.contains(v) {
         // Note that it is possible to have a `$var` inside a macro which is not bound.
@@ -140,8 +142,14 @@ fn expand_var(ctx: &mut ExpandCtx, v: &SmolStr, id: tt::TokenId) -> ExpandResult
         let tt = tt::Subtree {
             delimiter: None,
             token_trees: vec![
-                tt::Leaf::from(tt::Punct { char: '$', spacing: tt::Spacing::Alone, id }).into(),
-                tt::Leaf::from(tt::Ident { text: v.clone(), id }).into(),
+                tt::Leaf::from(tt::Punct {
+                    char: '$',
+                    spacing: tt::Spacing::Alone,
+                    id: tt::TokenId::unspecified(),
+                })
+                .into(),
+                tt::Leaf::from(tt::Ident { text: v.clone(), id: tt::TokenId::unspecified() })
+                    .into(),
             ],
         }
         .into();
diff --git a/crates/mbe/src/parser.rs b/crates/mbe/src/parser.rs
index 77cc739b6..2f3ebc831 100644
--- a/crates/mbe/src/parser.rs
+++ b/crates/mbe/src/parser.rs
@@ -8,7 +8,7 @@ use crate::{tt_iter::TtIter, ExpandError, MetaTemplate};
 
 #[derive(Clone, Debug, PartialEq, Eq)]
 pub(crate) enum Op {
-    Var { name: SmolStr, kind: Option<SmolStr>, id: tt::TokenId },
+    Var { name: SmolStr, kind: Option<SmolStr> },
     Repeat { subtree: MetaTemplate, kind: RepeatKind, separator: Option<Separator> },
     Leaf(tt::Leaf),
     Subtree(MetaTemplate),
@@ -106,21 +106,18 @@ fn next_op<'a>(first: &tt::TokenTree, src: &mut TtIter<'a>, mode: Mode) -> Resul
                         }
                         let name = UNDERSCORE.clone();
                         let kind = eat_fragment_kind(src, mode)?;
-                        let id = punct.id;
-                        Op::Var { name, kind, id }
+                        Op::Var { name, kind }
                     }
                     tt::Leaf::Ident(ident) => {
                         let name = ident.text.clone();
                         let kind = eat_fragment_kind(src, mode)?;
-                        let id = ident.id;
-                        Op::Var { name, kind, id }
+                        Op::Var { name, kind }
                     }
                     tt::Leaf::Literal(lit) => {
                         if is_boolean_literal(&lit) {
                             let name = lit.text.clone();
                             let kind = eat_fragment_kind(src, mode)?;
-                            let id = lit.id;
-                            Op::Var { name, kind, id }
+                            Op::Var { name, kind }
                         } else {
                             bail!("bad var 2");
                         }
diff --git a/crates/mbe/src/subtree_source.rs b/crates/mbe/src/subtree_source.rs
index d10d4b70e..d7433bd35 100644
--- a/crates/mbe/src/subtree_source.rs
+++ b/crates/mbe/src/subtree_source.rs
@@ -1,129 +1,104 @@
 //! FIXME: write short doc here
 
 use parser::{Token, TokenSource};
-use std::cell::{Cell, Ref, RefCell};
 use syntax::{lex_single_syntax_kind, SmolStr, SyntaxKind, SyntaxKind::*, T};
-use tt::buffer::{Cursor, TokenBuffer};
+use tt::buffer::TokenBuffer;
 
 #[derive(Debug, Clone, Eq, PartialEq)]
 struct TtToken {
-    kind: SyntaxKind,
-    is_joint_to_next: bool,
+    tt: Token,
     text: SmolStr,
 }
 
-pub(crate) struct SubtreeTokenSource<'a> {
-    cached_cursor: Cell<Cursor<'a>>,
-    cached: RefCell<Vec<Option<TtToken>>>,
+pub(crate) struct SubtreeTokenSource {
+    cached: Vec<TtToken>,
     curr: (Token, usize),
 }
 
-impl<'a> SubtreeTokenSource<'a> {
+impl<'a> SubtreeTokenSource {
     // Helper function used in test
     #[cfg(test)]
     pub(crate) fn text(&self) -> SmolStr {
-        match *self.get(self.curr.1) {
+        match self.cached.get(self.curr.1) {
             Some(ref tt) => tt.text.clone(),
             _ => SmolStr::new(""),
         }
     }
 }
 
-impl<'a> SubtreeTokenSource<'a> {
-    pub(crate) fn new(buffer: &'a TokenBuffer) -> SubtreeTokenSource<'a> {
-        let cursor = buffer.begin();
+impl<'a> SubtreeTokenSource {
+    pub(crate) fn new(buffer: &TokenBuffer) -> SubtreeTokenSource {
+        let mut current = buffer.begin();
+        let mut cached = Vec::with_capacity(100);
 
-        let mut res = SubtreeTokenSource {
-            curr: (Token { kind: EOF, is_jointed_to_next: false }, 0),
-            cached_cursor: Cell::new(cursor),
-            cached: RefCell::new(Vec::with_capacity(10)),
-        };
-        res.curr = (res.mk_token(0), 0);
-        res
-    }
+        while !current.eof() {
+            let cursor = current;
+            let tt = cursor.token_tree();
 
-    fn mk_token(&self, pos: usize) -> Token {
-        match *self.get(pos) {
-            Some(ref tt) => Token { kind: tt.kind, is_jointed_to_next: tt.is_joint_to_next },
-            None => Token { kind: EOF, is_jointed_to_next: false },
-        }
-    }
-
-    fn get(&self, pos: usize) -> Ref<Option<TtToken>> {
-        fn is_lifetime(c: Cursor) -> Option<(Cursor, SmolStr)> {
-            let tkn = c.token_tree();
-
-            if let Some(tt::TokenTree::Leaf(tt::Leaf::Punct(punct))) = tkn {
+            // Check if it is lifetime
+            if let Some(tt::buffer::TokenTreeRef::Leaf(tt::Leaf::Punct(punct), _)) = tt {
                 if punct.char == '\'' {
-                    let next = c.bump();
-                    if let Some(tt::TokenTree::Leaf(tt::Leaf::Ident(ident))) = next.token_tree() {
-                        let res_cursor = next.bump();
-                        let text = SmolStr::new("'".to_string() + &ident.to_string());
-
-                        return Some((res_cursor, text));
+                    let next = cursor.bump();
+                    if let Some(tt::buffer::TokenTreeRef::Leaf(tt::Leaf::Ident(ident), _)) =
+                        next.token_tree()
+                    {
+                        let text = SmolStr::new("'".to_string() + &ident.text);
+                        cached.push(TtToken {
+                            tt: Token { kind: LIFETIME_IDENT, is_jointed_to_next: false },
+                            text,
+                        });
+                        current = next.bump();
+                        continue;
                     } else {
                         panic!("Next token must be ident : {:#?}", next.token_tree());
                     }
                 }
             }
 
-            None
-        }
-
-        if pos < self.cached.borrow().len() {
-            return Ref::map(self.cached.borrow(), |c| &c[pos]);
-        }
-
-        {
-            let mut cached = self.cached.borrow_mut();
-            while pos >= cached.len() {
-                let cursor = self.cached_cursor.get();
-                if cursor.eof() {
-                    cached.push(None);
-                    continue;
+            current = match tt {
+                Some(tt::buffer::TokenTreeRef::Leaf(leaf, _)) => {
+                    cached.push(convert_leaf(&leaf));
+                    cursor.bump()
                 }
-
-                if let Some((curr, text)) = is_lifetime(cursor) {
-                    cached.push(Some(TtToken {
-                        kind: LIFETIME_IDENT,
-                        is_joint_to_next: false,
-                        text,
-                    }));
-                    self.cached_cursor.set(curr);
-                    continue;
+                Some(tt::buffer::TokenTreeRef::Subtree(subtree, _)) => {
+                    cached.push(convert_delim(subtree.delimiter_kind(), false));
+                    cursor.subtree().unwrap()
                 }
-
-                match cursor.token_tree() {
-                    Some(tt::TokenTree::Leaf(leaf)) => {
-                        cached.push(Some(convert_leaf(&leaf)));
-                        self.cached_cursor.set(cursor.bump());
-                    }
-                    Some(tt::TokenTree::Subtree(subtree)) => {
-                        self.cached_cursor.set(cursor.subtree().unwrap());
-                        cached.push(Some(convert_delim(subtree.delimiter_kind(), false)));
-                    }
-                    None => {
-                        if let Some(subtree) = cursor.end() {
-                            cached.push(Some(convert_delim(subtree.delimiter_kind(), true)));
-                            self.cached_cursor.set(cursor.bump());
-                        }
+                None => {
+                    if let Some(subtree) = cursor.end() {
+                        cached.push(convert_delim(subtree.delimiter_kind(), true));
+                        cursor.bump()
+                    } else {
+                        continue;
                     }
                 }
-            }
+            };
         }
 
-        Ref::map(self.cached.borrow(), |c| &c[pos])
+        let mut res = SubtreeTokenSource {
+            curr: (Token { kind: EOF, is_jointed_to_next: false }, 0),
+            cached,
+        };
+        res.curr = (res.token(0), 0);
+        res
+    }
+
+    fn token(&self, pos: usize) -> Token {
+        match self.cached.get(pos) {
+            Some(it) => it.tt,
+            None => Token { kind: EOF, is_jointed_to_next: false },
+        }
     }
 }
 
-impl<'a> TokenSource for SubtreeTokenSource<'a> {
+impl<'a> TokenSource for SubtreeTokenSource {
     fn current(&self) -> Token {
         self.curr.0
     }
 
     /// Lookahead n token
     fn lookahead_nth(&self, n: usize) -> Token {
-        self.mk_token(self.curr.1 + n)
+        self.token(self.curr.1 + n)
     }
 
     /// bump cursor to next token
@@ -131,13 +106,12 @@ impl<'a> TokenSource for SubtreeTokenSource<'a> {
         if self.current().kind == EOF {
             return;
         }
-
-        self.curr = (self.mk_token(self.curr.1 + 1), self.curr.1 + 1);
+        self.curr = (self.token(self.curr.1 + 1), self.curr.1 + 1);
     }
 
     /// Is the current token a specified keyword?
     fn is_keyword(&self, kw: &str) -> bool {
-        match *self.get(self.curr.1) {
+        match self.cached.get(self.curr.1) {
             Some(ref t) => t.text == *kw,
             _ => false,
         }
@@ -155,7 +129,7 @@ fn convert_delim(d: Option<tt::DelimiterKind>, closing: bool) -> TtToken {
     let idx = closing as usize;
     let kind = kinds[idx];
     let text = if !texts.is_empty() { &texts[idx..texts.len() - (1 - idx)] } else { "" };
-    TtToken { kind, is_joint_to_next: false, text: SmolStr::new(text) }
+    TtToken { tt: Token { kind, is_jointed_to_next: false }, text: SmolStr::new(text) }
 }
 
 fn convert_literal(l: &tt::Literal) -> TtToken {
@@ -169,7 +143,7 @@ fn convert_literal(l: &tt::Literal) -> TtToken {
         })
         .unwrap_or_else(|| panic!("Fail to convert given literal {:#?}", &l));
 
-    TtToken { kind, is_joint_to_next: false, text: l.text.clone() }
+    TtToken { tt: Token { kind, is_jointed_to_next: false }, text: l.text.clone() }
 }
 
 fn convert_ident(ident: &tt::Ident) -> TtToken {
@@ -180,7 +154,7 @@ fn convert_ident(ident: &tt::Ident) -> TtToken {
         _ => SyntaxKind::from_keyword(ident.text.as_str()).unwrap_or(IDENT),
     };
 
-    TtToken { kind, is_joint_to_next: false, text: ident.text.clone() }
+    TtToken { tt: Token { kind, is_jointed_to_next: false }, text: ident.text.clone() }
 }
 
 fn convert_punct(p: tt::Punct) -> TtToken {
@@ -194,7 +168,7 @@ fn convert_punct(p: tt::Punct) -> TtToken {
         let s: &str = p.char.encode_utf8(&mut buf);
         SmolStr::new(s)
     };
-    TtToken { kind, is_joint_to_next: p.spacing == tt::Spacing::Joint, text }
+    TtToken { tt: Token { kind, is_jointed_to_next: p.spacing == tt::Spacing::Joint }, text }
 }
 
 fn convert_leaf(leaf: &tt::Leaf) -> TtToken {
@@ -208,6 +182,7 @@ fn convert_leaf(leaf: &tt::Leaf) -> TtToken {
 #[cfg(test)]
 mod tests {
     use super::{convert_literal, TtToken};
+    use parser::Token;
     use syntax::{SmolStr, SyntaxKind};
 
     #[test]
@@ -218,8 +193,7 @@ mod tests {
                 text: SmolStr::new("-42.0")
             }),
             TtToken {
-                kind: SyntaxKind::FLOAT_NUMBER,
-                is_joint_to_next: false,
+                tt: Token { kind: SyntaxKind::FLOAT_NUMBER, is_jointed_to_next: false },
                 text: SmolStr::new("-42.0")
             }
         );
diff --git a/crates/mbe/src/syntax_bridge.rs b/crates/mbe/src/syntax_bridge.rs
index 265c0d63d..671036e1c 100644
--- a/crates/mbe/src/syntax_bridge.rs
+++ b/crates/mbe/src/syntax_bridge.rs
@@ -70,15 +70,12 @@ pub fn token_tree_to_syntax_node(
     tt: &tt::Subtree,
     fragment_kind: FragmentKind,
 ) -> Result<(Parse<SyntaxNode>, TokenMap), ExpandError> {
-    let tmp;
-    let tokens = match tt {
-        tt::Subtree { delimiter: None, token_trees } => token_trees.as_slice(),
-        _ => {
-            tmp = [tt.clone().into()];
-            &tmp[..]
+    let buffer = match tt {
+        tt::Subtree { delimiter: None, token_trees } => {
+            TokenBuffer::from_tokens(token_trees.as_slice())
         }
+        _ => TokenBuffer::from_subtree(tt),
     };
-    let buffer = TokenBuffer::new(&tokens);
     let mut token_source = SubtreeTokenSource::new(&buffer);
     let mut tree_sink = TtTreeSink::new(buffer.begin());
     parser::parse_fragment(&mut token_source, &mut tree_sink, fragment_kind);
@@ -414,7 +411,7 @@ trait TokenConvertor {
     fn id_alloc(&mut self) -> &mut TokenIdAlloc;
 }
 
-impl<'a> SrcToken for (RawToken, &'a str) {
+impl<'a> SrcToken for (&'a RawToken, &'a str) {
     fn kind(&self) -> SyntaxKind {
         self.0.kind
     }
@@ -431,7 +428,7 @@ impl<'a> SrcToken for (RawToken, &'a str) {
 impl RawConvertor<'_> {}
 
 impl<'a> TokenConvertor for RawConvertor<'a> {
-    type Token = (RawToken, &'a str);
+    type Token = (&'a RawToken, &'a str);
 
     fn convert_doc_comment(&self, token: &Self::Token) -> Option<Vec<tt::TokenTree>> {
         convert_doc_comment(&doc_comment(token.1))
@@ -442,11 +439,11 @@ impl<'a> TokenConvertor for RawConvertor<'a> {
         let range = TextRange::at(self.offset, token.len);
         self.offset += token.len;
 
-        Some(((*token, &self.text[range]), range))
+        Some(((token, &self.text[range]), range))
     }
 
     fn peek(&self) -> Option<Self::Token> {
-        let token = self.inner.as_slice().get(0).cloned();
+        let token = self.inner.as_slice().get(0);
 
         token.map(|it| {
             let range = TextRange::at(self.offset, it.len);
@@ -601,17 +598,16 @@ impl<'a> TtTreeSink<'a> {
     }
 }
 
-fn delim_to_str(d: Option<tt::DelimiterKind>, closing: bool) -> SmolStr {
+fn delim_to_str(d: Option<tt::DelimiterKind>, closing: bool) -> &'static str {
     let texts = match d {
         Some(tt::DelimiterKind::Parenthesis) => "()",
         Some(tt::DelimiterKind::Brace) => "{}",
         Some(tt::DelimiterKind::Bracket) => "[]",
-        None => return "".into(),
+        None => return "",
     };
 
     let idx = closing as usize;
-    let text = &texts[idx..texts.len() - (1 - idx)];
-    text.into()
+    &texts[idx..texts.len() - (1 - idx)]
 }
 
 impl<'a> TreeSink for TtTreeSink<'a> {
@@ -626,29 +622,32 @@ impl<'a> TreeSink for TtTreeSink<'a> {
 
         let mut last = self.cursor;
         for _ in 0..n_tokens {
+            let tmp_str: SmolStr;
             if self.cursor.eof() {
                 break;
             }
             last = self.cursor;
-            let text: SmolStr = match self.cursor.token_tree() {
-                Some(tt::TokenTree::Leaf(leaf)) => {
+            let text: &str = match self.cursor.token_tree() {
+                Some(tt::buffer::TokenTreeRef::Leaf(leaf, _)) => {
                     // Mark the range if needed
                     let (text, id) = match leaf {
-                        tt::Leaf::Ident(ident) => (ident.text.clone(), ident.id),
+                        tt::Leaf::Ident(ident) => (&ident.text, ident.id),
                         tt::Leaf::Punct(punct) => {
                             assert!(punct.char.is_ascii());
                             let char = &(punct.char as u8);
-                            let text = std::str::from_utf8(std::slice::from_ref(char)).unwrap();
-                            (SmolStr::new_inline(text), punct.id)
+                            tmp_str = SmolStr::new_inline(
+                                std::str::from_utf8(std::slice::from_ref(char)).unwrap(),
+                            );
+                            (&tmp_str, punct.id)
                         }
-                        tt::Leaf::Literal(lit) => (lit.text.clone(), lit.id),
+                        tt::Leaf::Literal(lit) => (&lit.text, lit.id),
                     };
                     let range = TextRange::at(self.text_pos, TextSize::of(text.as_str()));
                     self.token_map.insert(id, range);
                     self.cursor = self.cursor.bump();
                     text
                 }
-                Some(tt::TokenTree::Subtree(subtree)) => {
+                Some(tt::buffer::TokenTreeRef::Subtree(subtree, _)) => {
                     self.cursor = self.cursor.subtree().unwrap();
                     if let Some(id) = subtree.delimiter.map(|it| it.id) {
                         self.open_delims.insert(id, self.text_pos);
@@ -672,7 +671,7 @@ impl<'a> TreeSink for TtTreeSink<'a> {
                 }
             };
             self.buf += &text;
-            self.text_pos += TextSize::of(text.as_str());
+            self.text_pos += TextSize::of(text);
         }
 
         let text = SmolStr::new(self.buf.as_str());
@@ -682,8 +681,8 @@ impl<'a> TreeSink for TtTreeSink<'a> {
         // Add whitespace between adjoint puncts
         let next = last.bump();
         if let (
-            Some(tt::TokenTree::Leaf(tt::Leaf::Punct(curr))),
-            Some(tt::TokenTree::Leaf(tt::Leaf::Punct(_))),
+            Some(tt::buffer::TokenTreeRef::Leaf(tt::Leaf::Punct(curr), _)),
+            Some(tt::buffer::TokenTreeRef::Leaf(tt::Leaf::Punct(_), _)),
         ) = (last.token_tree(), next.token_tree())
         {
             // Note: We always assume the semi-colon would be the last token in
@@ -742,7 +741,7 @@ mod tests {
         )
         .expand_tt("literals!(foo);");
         let tts = &[expansion.into()];
-        let buffer = tt::buffer::TokenBuffer::new(tts);
+        let buffer = tt::buffer::TokenBuffer::from_tokens(tts);
         let mut tt_src = SubtreeTokenSource::new(&buffer);
         let mut tokens = vec![];
         while tt_src.current().kind != EOF {