From 6af1015f74ee8395ea7fe8339d8748089f05e3e4 Mon Sep 17 00:00:00 2001 From: Edwin Cheng Date: Sat, 4 Apr 2020 16:07:22 +0800 Subject: [PATCH 1/2] Add rustc_server (ra_tt rustc bridge) --- Cargo.lock | 1 + crates/ra_proc_macro_srv/Cargo.toml | 2 +- crates/ra_proc_macro_srv/src/lib.rs | 3 + crates/ra_proc_macro_srv/src/rustc_server.rs | 686 +++++++++++++++++++ 4 files changed, 691 insertions(+), 1 deletion(-) create mode 100644 crates/ra_proc_macro_srv/src/rustc_server.rs diff --git a/Cargo.lock b/Cargo.lock index eb9824218f3..34f05e83a33 100644 --- a/Cargo.lock +++ b/Cargo.lock @@ -1081,6 +1081,7 @@ version = "0.1.0" dependencies = [ "cargo_metadata", "difference", + "ra_mbe", "ra_proc_macro", "ra_tt", "serde_derive", diff --git a/crates/ra_proc_macro_srv/Cargo.toml b/crates/ra_proc_macro_srv/Cargo.toml index 6300d668ab0..f08de5fc771 100644 --- a/crates/ra_proc_macro_srv/Cargo.toml +++ b/crates/ra_proc_macro_srv/Cargo.toml @@ -10,9 +10,9 @@ doctest = false [dependencies] ra_tt = { path = "../ra_tt" } +ra_mbe = { path = "../ra_mbe" } ra_proc_macro = { path = "../ra_proc_macro" } - [dev-dependencies] cargo_metadata = "0.9.1" difference = "2.0.0" diff --git a/crates/ra_proc_macro_srv/src/lib.rs b/crates/ra_proc_macro_srv/src/lib.rs index 80cfa1174d2..f376df2367f 100644 --- a/crates/ra_proc_macro_srv/src/lib.rs +++ b/crates/ra_proc_macro_srv/src/lib.rs @@ -14,6 +14,9 @@ #[doc(hidden)] mod proc_macro; +#[doc(hidden)] +mod rustc_server; + use proc_macro::bridge::client::TokenStream; use ra_proc_macro::{ExpansionResult, ExpansionTask, ListMacrosResult, ListMacrosTask}; diff --git a/crates/ra_proc_macro_srv/src/rustc_server.rs b/crates/ra_proc_macro_srv/src/rustc_server.rs new file mode 100644 index 00000000000..76e6a2752ab --- /dev/null +++ b/crates/ra_proc_macro_srv/src/rustc_server.rs @@ -0,0 +1,686 @@ +//! Rustc proc-macro server implementation with ra_tt +//! +//! Based on idea from https://github.com/fedochet/rust-proc-macro-expander +//! The lib-proc-macro server backend is `TokenStream`-agnostic, such that +//! we could provide any TokenStream implementation. +//! The original idea from fedochet is using proc-macro2 as backend, +//! we use ra_tt instead for better intergation with RA. +//! +//! FIXME: No span and source file informatin is implemented yet + +use crate::proc_macro::bridge::{self, server}; +use ra_tt as tt; + +use std::collections::{Bound, HashMap}; +use std::hash::Hash; +use std::iter::FromIterator; +use std::str::FromStr; +use std::{ascii, vec::IntoIter}; + +type Group = tt::Subtree; +type TokenTree = tt::TokenTree; +type Punct = tt::Punct; +type Spacing = tt::Spacing; +type Literal = tt::Literal; +type Span = tt::TokenId; + +#[derive(Debug, Clone)] +pub struct TokenStream { + pub subtree: tt::Subtree, +} + +impl TokenStream { + pub fn new() -> Self { + TokenStream { subtree: Default::default() } + } + pub fn with_subtree(subtree: tt::Subtree) -> Self { + TokenStream { subtree } + } + pub fn is_empty(&self) -> bool { + self.subtree.token_trees.is_empty() + } +} + +/// Creates a token stream containing a single token tree. +impl From for TokenStream { + fn from(tree: TokenTree) -> TokenStream { + TokenStream { subtree: tt::Subtree { delimiter: None, token_trees: vec![tree] } } + } +} + +/// Collects a number of token trees into a single stream. +impl FromIterator for TokenStream { + fn from_iter>(trees: I) -> Self { + trees.into_iter().map(TokenStream::from).collect() + } +} + +/// A "flattening" operation on token streams, collects token trees +/// from multiple token streams into a single stream. +impl FromIterator for TokenStream { + fn from_iter>(streams: I) -> Self { + let mut builder = TokenStreamBuilder::new(); + streams.into_iter().for_each(|stream| builder.push(stream)); + builder.build() + } +} + +impl Extend for TokenStream { + fn extend>(&mut self, trees: I) { + self.extend(trees.into_iter().map(TokenStream::from)); + } +} + +impl Extend for TokenStream { + fn extend>(&mut self, streams: I) { + for item in streams { + self.subtree.token_trees.extend(&mut item.into_iter()) + } + } +} + +type Level = crate::proc_macro::Level; +type LineColumn = crate::proc_macro::LineColumn; +type SourceFile = crate::proc_macro::SourceFile; + +/// A structure representing a diagnostic message and associated children +/// messages. +#[derive(Clone, Debug)] +pub struct Diagnostic { + level: Level, + message: String, + spans: Vec, + children: Vec, +} + +impl Diagnostic { + /// Creates a new diagnostic with the given `level` and `message`. + pub fn new>(level: Level, message: T) -> Diagnostic { + Diagnostic { level, message: message.into(), spans: vec![], children: vec![] } + } +} + +// Rustc Server Ident has to be `Copyable` +// We use a stub here for bypassing +#[derive(Hash, Eq, PartialEq, Copy, Clone)] +pub struct IdentId(u32); + +#[derive(Clone, Hash, Eq, PartialEq)] +struct IdentData(tt::Ident); + +#[derive(Default)] +struct IdentInterner { + idents: HashMap, + ident_data: Vec, +} + +impl IdentInterner { + fn intern(&mut self, data: &IdentData) -> u32 { + if let Some(index) = self.idents.get(data) { + return *index; + } + + let index = self.idents.len() as u32; + self.ident_data.push(data.clone()); + self.idents.insert(data.clone(), index); + index + } + + fn get(&self, index: u32) -> &IdentData { + &self.ident_data[index as usize] + } + + #[allow(unused)] + fn get_mut(&mut self, index: u32) -> &mut IdentData { + self.ident_data.get_mut(index as usize).expect("Should be consistent") + } +} + +pub struct TokenStreamBuilder { + acc: TokenStream, +} + +/// Public implementation details for the `TokenStream` type, such as iterators. +pub mod token_stream { + use super::{tt, TokenStream, TokenTree}; + use std::str::FromStr; + + /// An iterator over `TokenStream`'s `TokenTree`s. + /// The iteration is "shallow", e.g., the iterator doesn't recurse into delimited groups, + /// and returns whole groups as token trees. + impl IntoIterator for TokenStream { + type Item = TokenTree; + type IntoIter = super::IntoIter; + + fn into_iter(self) -> Self::IntoIter { + self.subtree.token_trees.into_iter() + } + } + + type LexError = String; + + /// Attempts to break the string into tokens and parse those tokens into a token stream. + /// May fail for a number of reasons, for example, if the string contains unbalanced delimiters + /// or characters not existing in the language. + /// All tokens in the parsed stream get `Span::call_site()` spans. + /// + /// NOTE: some errors may cause panics instead of returning `LexError`. We reserve the right to + /// change these errors into `LexError`s later. + impl FromStr for TokenStream { + type Err = LexError; + + fn from_str(src: &str) -> Result { + let (subtree, _token_map) = + ra_mbe::parse_to_token_tree(src).ok_or("Failed to parse from mbe")?; + + let tt: tt::TokenTree = subtree.into(); + Ok(tt.into()) + } + } + + impl ToString for TokenStream { + fn to_string(&self) -> String { + let tt = self.subtree.clone().into(); + to_text(&tt) + } + } + + fn to_text(tkn: &tt::TokenTree) -> String { + match tkn { + tt::TokenTree::Leaf(tt::Leaf::Ident(ident)) => ident.text.clone().into(), + tt::TokenTree::Leaf(tt::Leaf::Literal(literal)) => literal.text.clone().into(), + tt::TokenTree::Leaf(tt::Leaf::Punct(punct)) => format!("{}", punct.char), + tt::TokenTree::Subtree(subtree) => { + let content = subtree + .token_trees + .iter() + .map(|tkn| { + let s = to_text(tkn); + if let tt::TokenTree::Leaf(tt::Leaf::Punct(punct)) = tkn { + if punct.spacing == tt::Spacing::Alone { + return s + " "; + } + } + s + }) + .collect::>() + .concat(); + let (open, close) = match subtree.delimiter.map(|it| it.kind) { + None => ("", ""), + Some(tt::DelimiterKind::Brace) => ("{", "}"), + Some(tt::DelimiterKind::Parenthesis) => ("(", ")"), + Some(tt::DelimiterKind::Bracket) => ("[", "]"), + }; + format!("{}{}{}", open, content, close) + } + } + } +} + +impl TokenStreamBuilder { + fn new() -> TokenStreamBuilder { + TokenStreamBuilder { acc: TokenStream::new() } + } + + fn push(&mut self, stream: TokenStream) { + self.acc.extend(stream.into_iter()) + } + + fn build(self) -> TokenStream { + self.acc + } +} + +#[derive(Clone)] +pub struct TokenStreamIter { + trees: IntoIter, +} + +#[derive(Default)] +pub struct Rustc { + ident_interner: IdentInterner, + // FIXME: store span information here. +} + +impl server::Types for Rustc { + type TokenStream = TokenStream; + type TokenStreamBuilder = TokenStreamBuilder; + type TokenStreamIter = TokenStreamIter; + type Group = Group; + type Punct = Punct; + type Ident = IdentId; + type Literal = Literal; + type SourceFile = SourceFile; + type Diagnostic = Diagnostic; + type Span = Span; + type MultiSpan = Vec; +} + +impl server::TokenStream for Rustc { + fn new(&mut self) -> Self::TokenStream { + Self::TokenStream::new() + } + + fn is_empty(&mut self, stream: &Self::TokenStream) -> bool { + stream.is_empty() + } + fn from_str(&mut self, src: &str) -> Self::TokenStream { + Self::TokenStream::from_str(src).expect("cannot parse string") + } + fn to_string(&mut self, stream: &Self::TokenStream) -> String { + stream.to_string() + } + fn from_token_tree( + &mut self, + tree: bridge::TokenTree, + ) -> Self::TokenStream { + match tree { + bridge::TokenTree::Group(group) => { + let tree = TokenTree::from(group); + Self::TokenStream::from_iter(vec![tree]) + } + + bridge::TokenTree::Ident(IdentId(index)) => { + let IdentData(ident) = self.ident_interner.get(index).clone(); + let ident: tt::Ident = ident; + let leaf = tt::Leaf::from(ident); + let tree = TokenTree::from(leaf); + Self::TokenStream::from_iter(vec![tree]) + } + + bridge::TokenTree::Literal(literal) => { + let leaf = tt::Leaf::from(literal); + let tree = TokenTree::from(leaf); + Self::TokenStream::from_iter(vec![tree]) + } + + bridge::TokenTree::Punct(p) => { + let leaf = tt::Leaf::from(p); + let tree = TokenTree::from(leaf); + Self::TokenStream::from_iter(vec![tree]) + } + } + } + + fn into_iter(&mut self, stream: Self::TokenStream) -> Self::TokenStreamIter { + let trees: Vec = stream.into_iter().collect(); + TokenStreamIter { trees: trees.into_iter() } + } +} + +impl server::TokenStreamBuilder for Rustc { + fn new(&mut self) -> Self::TokenStreamBuilder { + Self::TokenStreamBuilder::new() + } + fn push(&mut self, builder: &mut Self::TokenStreamBuilder, stream: Self::TokenStream) { + builder.push(stream) + } + fn build(&mut self, builder: Self::TokenStreamBuilder) -> Self::TokenStream { + builder.build() + } +} + +impl server::TokenStreamIter for Rustc { + fn next( + &mut self, + iter: &mut Self::TokenStreamIter, + ) -> Option> { + iter.trees.next().map(|tree| match tree { + TokenTree::Subtree(group) => bridge::TokenTree::Group(group), + TokenTree::Leaf(tt::Leaf::Ident(ident)) => { + bridge::TokenTree::Ident(IdentId(self.ident_interner.intern(&IdentData(ident)))) + } + TokenTree::Leaf(tt::Leaf::Literal(literal)) => bridge::TokenTree::Literal(literal), + TokenTree::Leaf(tt::Leaf::Punct(punct)) => bridge::TokenTree::Punct(punct), + }) + } +} + +fn delim_to_internal(d: bridge::Delimiter) -> Option { + let kind = match d { + bridge::Delimiter::Parenthesis => tt::DelimiterKind::Parenthesis, + bridge::Delimiter::Brace => tt::DelimiterKind::Brace, + bridge::Delimiter::Bracket => tt::DelimiterKind::Bracket, + bridge::Delimiter::None => return None, + }; + Some(tt::Delimiter { id: tt::TokenId::unspecified(), kind }) +} + +fn delim_to_external(d: Option) -> bridge::Delimiter { + match d.map(|it| it.kind) { + Some(tt::DelimiterKind::Parenthesis) => bridge::Delimiter::Parenthesis, + Some(tt::DelimiterKind::Brace) => bridge::Delimiter::Brace, + Some(tt::DelimiterKind::Bracket) => bridge::Delimiter::Bracket, + None => bridge::Delimiter::None, + } +} + +fn spacing_to_internal(spacing: bridge::Spacing) -> Spacing { + match spacing { + bridge::Spacing::Alone => Spacing::Alone, + bridge::Spacing::Joint => Spacing::Joint, + } +} + +fn spacing_to_external(spacing: Spacing) -> bridge::Spacing { + match spacing { + Spacing::Alone => bridge::Spacing::Alone, + Spacing::Joint => bridge::Spacing::Joint, + } +} + +impl server::Group for Rustc { + fn new(&mut self, delimiter: bridge::Delimiter, stream: Self::TokenStream) -> Self::Group { + Self::Group { + delimiter: delim_to_internal(delimiter), + token_trees: stream.subtree.token_trees, + } + } + fn delimiter(&mut self, group: &Self::Group) -> bridge::Delimiter { + delim_to_external(group.delimiter) + } + + // NOTE: Return value of do not include delimiter + fn stream(&mut self, group: &Self::Group) -> Self::TokenStream { + TokenStream { + subtree: tt::Subtree { delimiter: None, token_trees: group.token_trees.clone() }, + } + } + + fn span(&mut self, group: &Self::Group) -> Self::Span { + group.delimiter.map(|it| it.id).unwrap_or_else(|| tt::TokenId::unspecified()) + } + + fn set_span(&mut self, _group: &mut Self::Group, _span: Self::Span) { + // FIXME handle span + } + + fn span_open(&mut self, _group: &Self::Group) -> Self::Span { + // FIXME handle span + // MySpan(self.span_interner.intern(&MySpanData(group.span_open()))) + tt::TokenId::unspecified() + } + + fn span_close(&mut self, _group: &Self::Group) -> Self::Span { + // FIXME handle span + tt::TokenId::unspecified() + } +} + +impl server::Punct for Rustc { + fn new(&mut self, ch: char, spacing: bridge::Spacing) -> Self::Punct { + tt::Punct { + char: ch, + spacing: spacing_to_internal(spacing), + id: tt::TokenId::unspecified(), + } + } + fn as_char(&mut self, punct: Self::Punct) -> char { + punct.char + } + fn spacing(&mut self, punct: Self::Punct) -> bridge::Spacing { + spacing_to_external(punct.spacing) + } + fn span(&mut self, _punct: Self::Punct) -> Self::Span { + // FIXME handle span + tt::TokenId::unspecified() + } + fn with_span(&mut self, punct: Self::Punct, _span: Self::Span) -> Self::Punct { + // FIXME handle span + punct + } +} + +impl server::Ident for Rustc { + fn new(&mut self, string: &str, _span: Self::Span, _is_raw: bool) -> Self::Ident { + IdentId( + self.ident_interner.intern(&IdentData(tt::Ident { + text: string.into(), + id: tt::TokenId::unspecified(), + })), + ) + } + + fn span(&mut self, _ident: Self::Ident) -> Self::Span { + // FIXME handle span + tt::TokenId::unspecified() + } + fn with_span(&mut self, ident: Self::Ident, _span: Self::Span) -> Self::Ident { + // FIXME handle span + ident + } +} + +impl server::Literal for Rustc { + // FIXME(eddyb) `Literal` should not expose internal `Debug` impls. + fn debug(&mut self, literal: &Self::Literal) -> String { + format!("{:?}", literal) + } + + fn integer(&mut self, n: &str) -> Self::Literal { + let n: i128 = n.parse().unwrap(); + Literal { text: n.to_string().into(), id: tt::TokenId::unspecified() } + } + + fn typed_integer(&mut self, n: &str, kind: &str) -> Self::Literal { + macro_rules! def_suffixed_integer { + ($kind:ident, $($ty:ty),*) => { + match $kind { + $( + stringify!($ty) => { + let n: $ty = n.parse().unwrap(); + format!(concat!("{}", stringify!($ty)), n) + } + )* + _ => unimplemented!("unknown args for typed_integer: n {}, kind {}", n, $kind), + } + } + } + + let text = + def_suffixed_integer! {kind, u8, u16, u32, u64, u128, usize, i8, i16, i32, i64, i128}; + + Literal { text: text.into(), id: tt::TokenId::unspecified() } + } + + fn float(&mut self, n: &str) -> Self::Literal { + let n: f64 = n.parse().unwrap(); + let mut text = f64::to_string(&n); + if !text.contains('.') { + text += ".0" + } + Literal { text: text.into(), id: tt::TokenId::unspecified() } + } + + fn f32(&mut self, n: &str) -> Self::Literal { + let n: f32 = n.parse().unwrap(); + let text = format!("{}f32", n); + Literal { text: text.into(), id: tt::TokenId::unspecified() } + } + + fn f64(&mut self, n: &str) -> Self::Literal { + let n: f64 = n.parse().unwrap(); + let text = format!("{}f64", n); + Literal { text: text.into(), id: tt::TokenId::unspecified() } + } + + fn string(&mut self, string: &str) -> Self::Literal { + let mut escaped = String::new(); + for ch in string.chars() { + escaped.extend(ch.escape_debug()); + } + Literal { text: format!("\"{}\"", escaped).into(), id: tt::TokenId::unspecified() } + } + + fn character(&mut self, ch: char) -> Self::Literal { + Literal { text: format!("'{}'", ch).into(), id: tt::TokenId::unspecified() } + } + + fn byte_string(&mut self, bytes: &[u8]) -> Self::Literal { + let string = bytes + .iter() + .cloned() + .flat_map(ascii::escape_default) + .map(Into::::into) + .collect::(); + + Literal { text: format!("b\"{}\"", string).into(), id: tt::TokenId::unspecified() } + } + + fn span(&mut self, literal: &Self::Literal) -> Self::Span { + literal.id + } + + fn set_span(&mut self, _literal: &mut Self::Literal, _span: Self::Span) { + // FIXME handle span + } + + fn subspan( + &mut self, + _literal: &Self::Literal, + _start: Bound, + _end: Bound, + ) -> Option { + // FIXME handle span + None + } +} + +impl server::SourceFile for Rustc { + fn eq(&mut self, file1: &Self::SourceFile, file2: &Self::SourceFile) -> bool { + file1.eq(file2) + } + fn path(&mut self, file: &Self::SourceFile) -> String { + String::from( + file.path().to_str().expect("non-UTF8 file path in `proc_macro::SourceFile::path`"), + ) + } + fn is_real(&mut self, file: &Self::SourceFile) -> bool { + file.is_real() + } +} + +impl server::Diagnostic for Rustc { + fn new(&mut self, level: Level, msg: &str, spans: Self::MultiSpan) -> Self::Diagnostic { + let mut diag = Diagnostic::new(level, msg); + diag.spans = spans; + diag + } + + fn sub( + &mut self, + _diag: &mut Self::Diagnostic, + _level: Level, + _msg: &str, + _spans: Self::MultiSpan, + ) { + // FIXME handle diagnostic + // + } + + fn emit(&mut self, _diag: Self::Diagnostic) { + // FIXME handle diagnostic + // diag.emit() + } +} + +impl server::Span for Rustc { + fn debug(&mut self, span: Self::Span) -> String { + format!("{:?}", span.0) + } + fn def_site(&mut self) -> Self::Span { + // MySpan(self.span_interner.intern(&MySpanData(Span::def_site()))) + // FIXME handle span + tt::TokenId::unspecified() + } + fn call_site(&mut self) -> Self::Span { + // MySpan(self.span_interner.intern(&MySpanData(Span::call_site()))) + // FIXME handle span + tt::TokenId::unspecified() + } + fn source_file(&mut self, _span: Self::Span) -> Self::SourceFile { + // let MySpanData(span) = self.span_interner.get(span.0); + unimplemented!() + } + + /// Recent feature, not yet in the proc_macro + /// + /// See PR: + /// https://github.com/rust-lang/rust/pull/55780 + fn source_text(&mut self, _span: Self::Span) -> Option { + None + } + + fn parent(&mut self, _span: Self::Span) -> Option { + // FIXME handle span + None + } + fn source(&mut self, span: Self::Span) -> Self::Span { + // FIXME handle span + span + } + fn start(&mut self, _span: Self::Span) -> LineColumn { + // FIXME handle span + LineColumn { line: 0, column: 0 } + } + fn end(&mut self, _span: Self::Span) -> LineColumn { + // FIXME handle span + LineColumn { line: 0, column: 0 } + } + fn join(&mut self, _first: Self::Span, _second: Self::Span) -> Option { + None + } + fn resolved_at(&mut self, _span: Self::Span, _at: Self::Span) -> Self::Span { + // FIXME handle span + tt::TokenId::unspecified() + } + + fn mixed_site(&mut self) -> Self::Span { + // FIXME handle span + tt::TokenId::unspecified() + } +} + +impl server::MultiSpan for Rustc { + fn new(&mut self) -> Self::MultiSpan { + // FIXME handle span + vec![] + } + + fn push(&mut self, other: &mut Self::MultiSpan, span: Self::Span) { + //TODP + other.push(span) + } +} + +#[cfg(test)] +mod tests { + use super::*; + use crate::proc_macro::bridge::server::Literal; + + #[test] + fn test_rustc_server_literals() { + let mut srv = Rustc { ident_interner: IdentInterner::default() }; + assert_eq!(srv.integer("1234").text, "1234"); + + assert_eq!(srv.typed_integer("12", "u8").text, "12u8"); + assert_eq!(srv.typed_integer("255", "u16").text, "255u16"); + assert_eq!(srv.typed_integer("1234", "u32").text, "1234u32"); + assert_eq!(srv.typed_integer("15846685", "u64").text, "15846685u64"); + assert_eq!(srv.typed_integer("15846685258", "u128").text, "15846685258u128"); + assert_eq!(srv.typed_integer("156788984", "usize").text, "156788984usize"); + assert_eq!(srv.typed_integer("127", "i8").text, "127i8"); + assert_eq!(srv.typed_integer("255", "i16").text, "255i16"); + assert_eq!(srv.typed_integer("1234", "i32").text, "1234i32"); + assert_eq!(srv.typed_integer("15846685", "i64").text, "15846685i64"); + assert_eq!(srv.typed_integer("15846685258", "i128").text, "15846685258i128"); + assert_eq!(srv.float("0").text, "0.0"); + assert_eq!(srv.float("15684.5867").text, "15684.5867"); + assert_eq!(srv.f32("15684.58").text, "15684.58f32"); + assert_eq!(srv.f64("15684.58").text, "15684.58f64"); + + assert_eq!(srv.string("hello_world").text, "\"hello_world\""); + assert_eq!(srv.character('c').text, "'c'"); + assert_eq!(srv.byte_string(b"1234586\x88").text, "b\"1234586\\x88\""); + } +} From 836384393b3cb2dca003f4a2caf47e94f283f48c Mon Sep 17 00:00:00 2001 From: Edwin Cheng Date: Thu, 9 Apr 2020 12:28:58 +0800 Subject: [PATCH 2/2] Remove unused func --- crates/ra_proc_macro_srv/src/rustc_server.rs | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) diff --git a/crates/ra_proc_macro_srv/src/rustc_server.rs b/crates/ra_proc_macro_srv/src/rustc_server.rs index 76e6a2752ab..92d1fd989d3 100644 --- a/crates/ra_proc_macro_srv/src/rustc_server.rs +++ b/crates/ra_proc_macro_srv/src/rustc_server.rs @@ -33,9 +33,7 @@ impl TokenStream { pub fn new() -> Self { TokenStream { subtree: Default::default() } } - pub fn with_subtree(subtree: tt::Subtree) -> Self { - TokenStream { subtree } - } + pub fn is_empty(&self) -> bool { self.subtree.token_trees.is_empty() }