1 // Copyright 2012-2016 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
13 //! `TokenStream`s represent syntactic objects before they are converted into ASTs.
14 //! A `TokenStream` is, roughly speaking, a sequence (eg stream) of `TokenTree`s,
15 //! which are themselves a single `Token` or a `Delimited` subsequence of tokens.
18 //! `TokenStreams` are persistent data structures constructed as ropes with reference
19 //! counted-children. In general, this means that calling an operation on a `TokenStream`
20 //! (such as `slice`) produces an entirely new `TokenStream` from the borrowed reference to
21 //! the original. This essentially coerces `TokenStream`s into 'views' of their subparts,
22 //! and a borrowed `TokenStream` is sufficient to build an owned `TokenStream` without taking
23 //! ownership of the original.
25 use syntax_pos::{BytePos, Span, DUMMY_SP};
27 use ext::tt::{macro_parser, quoted};
29 use parse::token::{self, Token};
31 use serialize::{Decoder, Decodable, Encoder, Encodable};
34 use std::{fmt, iter, mem};
35 use std::hash::{self, Hash};
37 /// A delimited sequence of token trees
38 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
39 pub struct Delimited {
40 /// The type of delimiter
41 pub delim: token::DelimToken,
42 /// The delimited sequence of token trees
43 pub tts: ThinTokenStream,
47 /// Returns the opening delimiter as a token.
48 pub fn open_token(&self) -> token::Token {
49 token::OpenDelim(self.delim)
52 /// Returns the closing delimiter as a token.
53 pub fn close_token(&self) -> token::Token {
54 token::CloseDelim(self.delim)
57 /// Returns the opening delimiter as a token tree.
58 pub fn open_tt(&self, span: Span) -> TokenTree {
59 let open_span = if span == DUMMY_SP {
62 span.with_hi(span.lo() + BytePos(self.delim.len() as u32))
64 TokenTree::Token(open_span, self.open_token())
67 /// Returns the closing delimiter as a token tree.
68 pub fn close_tt(&self, span: Span) -> TokenTree {
69 let close_span = if span == DUMMY_SP {
72 span.with_lo(span.hi() - BytePos(self.delim.len() as u32))
74 TokenTree::Token(close_span, self.close_token())
77 /// Returns the token trees inside the delimiters.
78 pub fn stream(&self) -> TokenStream {
79 self.tts.clone().into()
83 /// When the main rust parser encounters a syntax-extension invocation, it
84 /// parses the arguments to the invocation as a token-tree. This is a very
85 /// loose structure, such that all sorts of different AST-fragments can
86 /// be passed to syntax extensions using a uniform type.
88 /// If the syntax extension is an MBE macro, it will attempt to match its
89 /// LHS token tree against the provided token tree, and if it finds a
90 /// match, will transcribe the RHS token tree, splicing in any captured
91 /// `macro_parser::matched_nonterminals` into the `SubstNt`s it finds.
93 /// The RHS of an MBE macro is the only place `SubstNt`s are substituted.
94 /// Nothing special happens to misnamed or misplaced `SubstNt`s.
95 #[derive(Debug, Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash)]
98 Token(Span, token::Token),
99 /// A delimited sequence of token trees
100 Delimited(Span, Delimited),
104 /// Use this token tree as a matcher to parse given tts.
105 pub fn parse(cx: &base::ExtCtxt, mtch: &[quoted::TokenTree], tts: TokenStream)
106 -> macro_parser::NamedParseResult {
107 // `None` is because we're not interpolating
108 let directory = Directory {
109 path: cx.current_expansion.module.directory.clone(),
110 ownership: cx.current_expansion.directory_ownership,
112 macro_parser::parse(cx.parse_sess(), tts, mtch, Some(directory), true)
115 /// Check if this TokenTree is equal to the other, regardless of span information.
116 pub fn eq_unspanned(&self, other: &TokenTree) -> bool {
117 match (self, other) {
118 (&TokenTree::Token(_, ref tk), &TokenTree::Token(_, ref tk2)) => tk == tk2,
119 (&TokenTree::Delimited(_, ref dl), &TokenTree::Delimited(_, ref dl2)) => {
120 dl.delim == dl2.delim &&
121 dl.stream().trees().zip(dl2.stream().trees()).all(|(tt, tt2)| tt.eq_unspanned(&tt2))
127 /// Retrieve the TokenTree's span.
128 pub fn span(&self) -> Span {
130 TokenTree::Token(sp, _) | TokenTree::Delimited(sp, _) => sp,
134 /// Modify the `TokenTree`'s span inplace.
135 pub fn set_span(&mut self, span: Span) {
137 TokenTree::Token(ref mut sp, _) | TokenTree::Delimited(ref mut sp, _) => {
143 /// Indicates if the stream is a token that is equal to the provided token.
144 pub fn eq_token(&self, t: Token) -> bool {
146 TokenTree::Token(_, ref tk) => *tk == t,
151 pub fn joint(self) -> TokenStream {
152 TokenStream { kind: TokenStreamKind::JointTree(self) }
158 /// A `TokenStream` is an abstract sequence of tokens, organized into `TokenTree`s.
159 /// The goal is for procedural macros to work with `TokenStream`s and `TokenTree`s
160 /// instead of a representation of the abstract syntax tree.
161 /// Today's `TokenTree`s can still contain AST via `Token::Interpolated` for back-compat.
162 #[derive(Clone, Debug)]
163 pub struct TokenStream {
164 kind: TokenStreamKind,
167 #[derive(Clone, Debug)]
168 enum TokenStreamKind {
171 JointTree(TokenTree),
172 Stream(RcSlice<TokenStream>),
175 impl From<TokenTree> for TokenStream {
176 fn from(tt: TokenTree) -> TokenStream {
177 TokenStream { kind: TokenStreamKind::Tree(tt) }
181 impl From<Token> for TokenStream {
182 fn from(token: Token) -> TokenStream {
183 TokenTree::Token(DUMMY_SP, token).into()
187 impl<T: Into<TokenStream>> iter::FromIterator<T> for TokenStream {
188 fn from_iter<I: IntoIterator<Item = T>>(iter: I) -> Self {
189 TokenStream::concat(iter.into_iter().map(Into::into).collect::<Vec<_>>())
193 impl Eq for TokenStream {}
195 impl PartialEq<TokenStream> for TokenStream {
196 fn eq(&self, other: &TokenStream) -> bool {
197 self.trees().eq(other.trees())
202 pub fn len(&self) -> usize {
203 if let TokenStreamKind::Stream(ref slice) = self.kind {
210 pub fn empty() -> TokenStream {
211 TokenStream { kind: TokenStreamKind::Empty }
214 pub fn is_empty(&self) -> bool {
216 TokenStreamKind::Empty => true,
221 pub fn concat(mut streams: Vec<TokenStream>) -> TokenStream {
222 match streams.len() {
223 0 => TokenStream::empty(),
224 1 => streams.pop().unwrap(),
225 _ => TokenStream::concat_rc_slice(RcSlice::new(streams)),
229 fn concat_rc_slice(streams: RcSlice<TokenStream>) -> TokenStream {
230 TokenStream { kind: TokenStreamKind::Stream(streams) }
233 pub fn trees(&self) -> Cursor {
234 self.clone().into_trees()
237 pub fn into_trees(self) -> Cursor {
241 /// Compares two TokenStreams, checking equality without regarding span information.
242 pub fn eq_unspanned(&self, other: &TokenStream) -> bool {
243 for (t1, t2) in self.trees().zip(other.trees()) {
244 if !t1.eq_unspanned(&t2) {
251 /// Precondition: `self` consists of a single token tree.
252 /// Returns true if the token tree is a joint operation w.r.t. `proc_macro::TokenNode`.
253 pub fn as_tree(self) -> (TokenTree, bool /* joint? */) {
255 TokenStreamKind::Tree(tree) => (tree, false),
256 TokenStreamKind::JointTree(tree) => (tree, true),
261 pub fn map_enumerated<F: FnMut(usize, TokenTree) -> TokenTree>(self, mut f: F) -> TokenStream {
262 let mut trees = self.into_trees();
263 let mut result = Vec::new();
265 while let Some(stream) = trees.next_as_stream() {
266 result.push(match stream.kind {
267 TokenStreamKind::Tree(tree) => f(i, tree).into(),
268 TokenStreamKind::JointTree(tree) => f(i, tree).joint(),
273 TokenStream::concat(result)
276 pub fn map<F: FnMut(TokenTree) -> TokenTree>(self, mut f: F) -> TokenStream {
277 let mut trees = self.into_trees();
278 let mut result = Vec::new();
279 while let Some(stream) = trees.next_as_stream() {
280 result.push(match stream.kind {
281 TokenStreamKind::Tree(tree) => f(tree).into(),
282 TokenStreamKind::JointTree(tree) => f(tree).joint(),
286 TokenStream::concat(result)
289 fn first_tree(&self) -> Option<TokenTree> {
291 TokenStreamKind::Empty => None,
292 TokenStreamKind::Tree(ref tree) |
293 TokenStreamKind::JointTree(ref tree) => Some(tree.clone()),
294 TokenStreamKind::Stream(ref stream) => stream.first().unwrap().first_tree(),
298 fn last_tree_if_joint(&self) -> Option<TokenTree> {
300 TokenStreamKind::Empty | TokenStreamKind::Tree(..) => None,
301 TokenStreamKind::JointTree(ref tree) => Some(tree.clone()),
302 TokenStreamKind::Stream(ref stream) => stream.last().unwrap().last_tree_if_joint(),
307 pub struct TokenStreamBuilder(Vec<TokenStream>);
309 impl TokenStreamBuilder {
310 pub fn new() -> TokenStreamBuilder {
311 TokenStreamBuilder(Vec::new())
314 pub fn push<T: Into<TokenStream>>(&mut self, stream: T) {
315 let stream = stream.into();
316 let last_tree_if_joint = self.0.last().and_then(TokenStream::last_tree_if_joint);
317 if let Some(TokenTree::Token(last_span, last_tok)) = last_tree_if_joint {
318 if let Some(TokenTree::Token(span, tok)) = stream.first_tree() {
319 if let Some(glued_tok) = last_tok.glue(tok) {
320 let last_stream = self.0.pop().unwrap();
321 self.push_all_but_last_tree(&last_stream);
322 let glued_span = last_span.to(span);
323 self.0.push(TokenTree::Token(glued_span, glued_tok).into());
324 self.push_all_but_first_tree(&stream);
332 pub fn add<T: Into<TokenStream>>(mut self, stream: T) -> Self {
337 pub fn build(self) -> TokenStream {
338 TokenStream::concat(self.0)
341 fn push_all_but_last_tree(&mut self, stream: &TokenStream) {
342 if let TokenStreamKind::Stream(ref streams) = stream.kind {
343 let len = streams.len();
346 2 => self.0.push(streams[0].clone().into()),
347 _ => self.0.push(TokenStream::concat_rc_slice(streams.sub_slice(0 .. len - 1))),
349 self.push_all_but_last_tree(&streams[len - 1])
353 fn push_all_but_first_tree(&mut self, stream: &TokenStream) {
354 if let TokenStreamKind::Stream(ref streams) = stream.kind {
355 let len = streams.len();
358 2 => self.0.push(streams[1].clone().into()),
359 _ => self.0.push(TokenStream::concat_rc_slice(streams.sub_slice(1 .. len))),
361 self.push_all_but_first_tree(&streams[0])
367 pub struct Cursor(CursorKind);
372 Tree(TokenTree, bool /* consumed? */),
373 JointTree(TokenTree, bool /* consumed? */),
374 Stream(StreamCursor),
378 struct StreamCursor {
379 stream: RcSlice<TokenStream>,
381 stack: Vec<(RcSlice<TokenStream>, usize)>,
385 fn new(stream: RcSlice<TokenStream>) -> Self {
386 StreamCursor { stream: stream, index: 0, stack: Vec::new() }
389 fn next_as_stream(&mut self) -> Option<TokenStream> {
391 if self.index < self.stream.len() {
393 let next = self.stream[self.index - 1].clone();
395 TokenStreamKind::Tree(..) | TokenStreamKind::JointTree(..) => return Some(next),
396 TokenStreamKind::Stream(stream) => self.insert(stream),
397 TokenStreamKind::Empty => {}
399 } else if let Some((stream, index)) = self.stack.pop() {
400 self.stream = stream;
408 fn insert(&mut self, stream: RcSlice<TokenStream>) {
409 self.stack.push((mem::replace(&mut self.stream, stream),
410 mem::replace(&mut self.index, 0)));
414 impl Iterator for Cursor {
415 type Item = TokenTree;
417 fn next(&mut self) -> Option<TokenTree> {
418 self.next_as_stream().map(|stream| match stream.kind {
419 TokenStreamKind::Tree(tree) | TokenStreamKind::JointTree(tree) => tree,
426 fn new(stream: TokenStream) -> Self {
427 Cursor(match stream.kind {
428 TokenStreamKind::Empty => CursorKind::Empty,
429 TokenStreamKind::Tree(tree) => CursorKind::Tree(tree, false),
430 TokenStreamKind::JointTree(tree) => CursorKind::JointTree(tree, false),
431 TokenStreamKind::Stream(stream) => CursorKind::Stream(StreamCursor::new(stream)),
435 pub fn next_as_stream(&mut self) -> Option<TokenStream> {
436 let (stream, consumed) = match self.0 {
437 CursorKind::Tree(ref tree, ref mut consumed @ false) =>
438 (tree.clone().into(), consumed),
439 CursorKind::JointTree(ref tree, ref mut consumed @ false) =>
440 (tree.clone().joint(), consumed),
441 CursorKind::Stream(ref mut cursor) => return cursor.next_as_stream(),
449 pub fn insert(&mut self, stream: TokenStream) {
451 _ if stream.is_empty() => return,
452 CursorKind::Empty => *self = stream.trees(),
453 CursorKind::Tree(_, consumed) | CursorKind::JointTree(_, consumed) => {
454 *self = TokenStream::concat(vec![self.original_stream(), stream]).trees();
459 CursorKind::Stream(ref mut cursor) => {
460 cursor.insert(ThinTokenStream::from(stream).0.unwrap());
465 pub fn original_stream(&self) -> TokenStream {
467 CursorKind::Empty => TokenStream::empty(),
468 CursorKind::Tree(ref tree, _) => tree.clone().into(),
469 CursorKind::JointTree(ref tree, _) => tree.clone().joint(),
470 CursorKind::Stream(ref cursor) => TokenStream::concat_rc_slice({
471 cursor.stack.get(0).cloned().map(|(stream, _)| stream)
472 .unwrap_or(cursor.stream.clone())
477 pub fn look_ahead(&self, n: usize) -> Option<TokenTree> {
478 fn look_ahead(streams: &[TokenStream], mut n: usize) -> Result<TokenTree, usize> {
479 for stream in streams {
480 n = match stream.kind {
481 TokenStreamKind::Tree(ref tree) | TokenStreamKind::JointTree(ref tree)
482 if n == 0 => return Ok(tree.clone()),
483 TokenStreamKind::Tree(..) | TokenStreamKind::JointTree(..) => n - 1,
484 TokenStreamKind::Stream(ref stream) => match look_ahead(stream, n) {
485 Ok(tree) => return Ok(tree),
496 CursorKind::Tree(_, true) |
497 CursorKind::JointTree(_, true) => Err(n),
498 CursorKind::Tree(ref tree, false) |
499 CursorKind::JointTree(ref tree, false) => look_ahead(&[tree.clone().into()], n),
500 CursorKind::Stream(ref cursor) => {
501 look_ahead(&cursor.stream[cursor.index ..], n).or_else(|mut n| {
502 for &(ref stream, index) in cursor.stack.iter().rev() {
503 n = match look_ahead(&stream[index..], n) {
504 Ok(tree) => return Ok(tree),
516 /// The `TokenStream` type is large enough to represent a single `TokenTree` without allocation.
517 /// `ThinTokenStream` is smaller, but needs to allocate to represent a single `TokenTree`.
518 /// We must use `ThinTokenStream` in `TokenTree::Delimited` to avoid infinite size due to recursion.
519 #[derive(Debug, Clone)]
520 pub struct ThinTokenStream(Option<RcSlice<TokenStream>>);
522 impl From<TokenStream> for ThinTokenStream {
523 fn from(stream: TokenStream) -> ThinTokenStream {
524 ThinTokenStream(match stream.kind {
525 TokenStreamKind::Empty => None,
526 TokenStreamKind::Tree(tree) => Some(RcSlice::new(vec![tree.into()])),
527 TokenStreamKind::JointTree(tree) => Some(RcSlice::new(vec![tree.joint()])),
528 TokenStreamKind::Stream(stream) => Some(stream),
533 impl From<ThinTokenStream> for TokenStream {
534 fn from(stream: ThinTokenStream) -> TokenStream {
535 stream.0.map(TokenStream::concat_rc_slice).unwrap_or_else(TokenStream::empty)
539 impl Eq for ThinTokenStream {}
541 impl PartialEq<ThinTokenStream> for ThinTokenStream {
542 fn eq(&self, other: &ThinTokenStream) -> bool {
543 TokenStream::from(self.clone()) == TokenStream::from(other.clone())
547 impl fmt::Display for TokenStream {
548 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
549 f.write_str(&pprust::tokens_to_string(self.clone()))
553 impl Encodable for TokenStream {
554 fn encode<E: Encoder>(&self, encoder: &mut E) -> Result<(), E::Error> {
555 self.trees().collect::<Vec<_>>().encode(encoder)
559 impl Decodable for TokenStream {
560 fn decode<D: Decoder>(decoder: &mut D) -> Result<TokenStream, D::Error> {
561 Vec::<TokenTree>::decode(decoder).map(|vec| vec.into_iter().collect())
565 impl Hash for TokenStream {
566 fn hash<H: hash::Hasher>(&self, state: &mut H) {
567 for tree in self.trees() {
573 impl Encodable for ThinTokenStream {
574 fn encode<E: Encoder>(&self, encoder: &mut E) -> Result<(), E::Error> {
575 TokenStream::from(self.clone()).encode(encoder)
579 impl Decodable for ThinTokenStream {
580 fn decode<D: Decoder>(decoder: &mut D) -> Result<ThinTokenStream, D::Error> {
581 TokenStream::decode(decoder).map(Into::into)
585 impl Hash for ThinTokenStream {
586 fn hash<H: hash::Hasher>(&self, state: &mut H) {
587 TokenStream::from(self.clone()).hash(state);
595 use syntax::ast::Ident;
596 use syntax_pos::{Span, BytePos, NO_EXPANSION};
597 use parse::token::Token;
598 use util::parser_testing::string_to_stream;
600 fn string_to_ts(string: &str) -> TokenStream {
601 string_to_stream(string.to_owned())
604 fn sp(a: u32, b: u32) -> Span {
605 Span::new(BytePos(a), BytePos(b), NO_EXPANSION)
610 let test_res = string_to_ts("foo::bar::baz");
611 let test_fst = string_to_ts("foo::bar");
612 let test_snd = string_to_ts("::baz");
613 let eq_res = TokenStream::concat(vec![test_fst, test_snd]);
614 assert_eq!(test_res.trees().count(), 5);
615 assert_eq!(eq_res.trees().count(), 5);
616 assert_eq!(test_res.eq_unspanned(&eq_res), true);
620 fn test_to_from_bijection() {
621 let test_start = string_to_ts("foo::bar(baz)");
622 let test_end = test_start.trees().collect();
623 assert_eq!(test_start, test_end)
628 let test_res = string_to_ts("foo");
629 let test_eqs = string_to_ts("foo");
630 assert_eq!(test_res, test_eqs)
635 let test_res = string_to_ts("::bar::baz");
636 let test_eqs = string_to_ts("::bar::baz");
637 assert_eq!(test_res, test_eqs)
642 let test_res = string_to_ts("");
643 let test_eqs = string_to_ts("");
644 assert_eq!(test_res, test_eqs)
649 let test_res = string_to_ts("::bar::baz");
650 let test_eqs = string_to_ts("bar::baz");
651 assert_eq!(test_res == test_eqs, false)
656 let test_res = string_to_ts("(bar,baz)");
657 let test_eqs = string_to_ts("bar,baz");
658 assert_eq!(test_res == test_eqs, false)
663 let test0: TokenStream = Vec::<TokenTree>::new().into_iter().collect();
664 let test1: TokenStream =
665 TokenTree::Token(sp(0, 1), Token::Ident(Ident::from_str("a"))).into();
666 let test2 = string_to_ts("foo(bar::baz)");
668 assert_eq!(test0.is_empty(), true);
669 assert_eq!(test1.is_empty(), false);
670 assert_eq!(test2.is_empty(), false);