proc_macro2/lib.rs
1//! [![github]](https://github.com/dtolnay/proc-macro2) [![crates-io]](https://crates.io/crates/proc-macro2) [![docs-rs]](crate)
2//!
3//! [github]: https://img.shields.io/badge/github-8da0cb?style=for-the-badge&labelColor=555555&logo=github
4//! [crates-io]: https://img.shields.io/badge/crates.io-fc8d62?style=for-the-badge&labelColor=555555&logo=rust
5//! [docs-rs]: https://img.shields.io/badge/docs.rs-66c2a5?style=for-the-badge&labelColor=555555&logo=docs.rs
6//!
7//! <br>
8//!
9//! A wrapper around the procedural macro API of the compiler's [`proc_macro`]
10//! crate. This library serves two purposes:
11//!
12//! - **Bring proc-macro-like functionality to other contexts like build.rs and
13//! main.rs.** Types from `proc_macro` are entirely specific to procedural
14//! macros and cannot ever exist in code outside of a procedural macro.
15//! Meanwhile `proc_macro2` types may exist anywhere including non-macro code.
16//! By developing foundational libraries like [syn] and [quote] against
17//! `proc_macro2` rather than `proc_macro`, the procedural macro ecosystem
18//! becomes easily applicable to many other use cases and we avoid
19//! reimplementing non-macro equivalents of those libraries.
20//!
21//! - **Make procedural macros unit testable.** As a consequence of being
22//! specific to procedural macros, nothing that uses `proc_macro` can be
23//! executed from a unit test. In order for helper libraries or components of
24//! a macro to be testable in isolation, they must be implemented using
25//! `proc_macro2`.
26//!
27//! [syn]: https://github.com/dtolnay/syn
28//! [quote]: https://github.com/dtolnay/quote
29//!
30//! # Usage
31//!
32//! The skeleton of a typical procedural macro typically looks like this:
33//!
34//! ```
35//! extern crate proc_macro;
36//!
37//! # const IGNORE: &str = stringify! {
38//! #[proc_macro_derive(MyDerive)]
39//! # };
40//! # #[cfg(wrap_proc_macro)]
41//! pub fn my_derive(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
42//! let input = proc_macro2::TokenStream::from(input);
43//!
44//! let output: proc_macro2::TokenStream = {
45//! /* transform input */
46//! # input
47//! };
48//!
49//! proc_macro::TokenStream::from(output)
50//! }
51//! ```
52//!
53//! If parsing with [Syn], you'll use [`parse_macro_input!`] instead to
54//! propagate parse errors correctly back to the compiler when parsing fails.
55//!
56//! [`parse_macro_input!`]: https://docs.rs/syn/2.0/syn/macro.parse_macro_input.html
57//!
58//! # Unstable features
59//!
60//! The default feature set of proc-macro2 tracks the most recent stable
61//! compiler API. Functionality in `proc_macro` that is not yet stable is not
62//! exposed by proc-macro2 by default.
63//!
64//! To opt into the additional APIs available in the most recent nightly
65//! compiler, the `procmacro2_semver_exempt` config flag must be passed to
66//! rustc. We will polyfill those nightly-only APIs back to Rust 1.56.0. As
67//! these are unstable APIs that track the nightly compiler, minor versions of
68//! proc-macro2 may make breaking changes to them at any time.
69//!
70//! ```sh
71//! RUSTFLAGS='--cfg procmacro2_semver_exempt' cargo build
72//! ```
73//!
74//! Note that this must not only be done for your crate, but for any crate that
75//! depends on your crate. This infectious nature is intentional, as it serves
76//! as a reminder that you are outside of the normal semver guarantees.
77//!
78//! Semver exempt methods are marked as such in the proc-macro2 documentation.
79//!
80//! # Thread-Safety
81//!
82//! Most types in this crate are `!Sync` because the underlying compiler
83//! types make use of thread-local memory, meaning they cannot be accessed from
84//! a different thread.
85
86// Proc-macro2 types in rustdoc of other crates get linked to here.
87#![doc(html_root_url = "https://docs.rs/proc-macro2/1.0.94")]
88#![cfg_attr(any(proc_macro_span, super_unstable), feature(proc_macro_span))]
89#![cfg_attr(super_unstable, feature(proc_macro_def_site))]
90#![cfg_attr(docsrs, feature(doc_cfg))]
91#![deny(unsafe_op_in_unsafe_fn)]
92#![allow(
93 clippy::cast_lossless,
94 clippy::cast_possible_truncation,
95 clippy::checked_conversions,
96 clippy::doc_markdown,
97 clippy::elidable_lifetime_names,
98 clippy::incompatible_msrv,
99 clippy::items_after_statements,
100 clippy::iter_without_into_iter,
101 clippy::let_underscore_untyped,
102 clippy::manual_assert,
103 clippy::manual_range_contains,
104 clippy::missing_panics_doc,
105 clippy::missing_safety_doc,
106 clippy::must_use_candidate,
107 clippy::needless_doctest_main,
108 clippy::needless_lifetimes,
109 clippy::new_without_default,
110 clippy::return_self_not_must_use,
111 clippy::shadow_unrelated,
112 clippy::trivially_copy_pass_by_ref,
113 clippy::unnecessary_wraps,
114 clippy::unused_self,
115 clippy::used_underscore_binding,
116 clippy::vec_init_then_push
117)]
118
119#[cfg(all(procmacro2_semver_exempt, wrap_proc_macro, not(super_unstable)))]
120compile_error! {"\
121 Something is not right. If you've tried to turn on \
122 procmacro2_semver_exempt, you need to ensure that it \
123 is turned on for the compilation of the proc-macro2 \
124 build script as well.
125"}
126
127#[cfg(all(
128 procmacro2_nightly_testing,
129 feature = "proc-macro",
130 not(proc_macro_span)
131))]
132compile_error! {"\
133 Build script probe failed to compile.
134"}
135
136extern crate alloc;
137
138#[cfg(feature = "proc-macro")]
139extern crate proc_macro;
140
141mod marker;
142mod parse;
143mod rcvec;
144
145#[cfg(wrap_proc_macro)]
146mod detection;
147
148// Public for proc_macro2::fallback::force() and unforce(), but those are quite
149// a niche use case so we omit it from rustdoc.
150#[doc(hidden)]
151pub mod fallback;
152
153pub mod extra;
154
155#[cfg(not(wrap_proc_macro))]
156use crate::fallback as imp;
157#[path = "wrapper.rs"]
158#[cfg(wrap_proc_macro)]
159mod imp;
160
161#[cfg(span_locations)]
162mod location;
163
164use crate::extra::DelimSpan;
165use crate::marker::{ProcMacroAutoTraits, MARKER};
166use core::cmp::Ordering;
167use core::fmt::{self, Debug, Display};
168use core::hash::{Hash, Hasher};
169#[cfg(span_locations)]
170use core::ops::Range;
171use core::ops::RangeBounds;
172use core::str::FromStr;
173use std::error::Error;
174use std::ffi::CStr;
175#[cfg(procmacro2_semver_exempt)]
176use std::path::PathBuf;
177
178#[cfg(span_locations)]
179#[cfg_attr(docsrs, doc(cfg(feature = "span-locations")))]
180pub use crate::location::LineColumn;
181
182/// An abstract stream of tokens, or more concretely a sequence of token trees.
183///
184/// This type provides interfaces for iterating over token trees and for
185/// collecting token trees into one stream.
186///
187/// Token stream is both the input and output of `#[proc_macro]`,
188/// `#[proc_macro_attribute]` and `#[proc_macro_derive]` definitions.
189#[derive(Clone)]
190pub struct TokenStream {
191 inner: imp::TokenStream,
192 _marker: ProcMacroAutoTraits,
193}
194
195/// Error returned from `TokenStream::from_str`.
196pub struct LexError {
197 inner: imp::LexError,
198 _marker: ProcMacroAutoTraits,
199}
200
201impl TokenStream {
202 fn _new(inner: imp::TokenStream) -> Self {
203 TokenStream {
204 inner,
205 _marker: MARKER,
206 }
207 }
208
209 fn _new_fallback(inner: fallback::TokenStream) -> Self {
210 TokenStream {
211 inner: imp::TokenStream::from(inner),
212 _marker: MARKER,
213 }
214 }
215
216 /// Returns an empty `TokenStream` containing no token trees.
217 pub fn new() -> Self {
218 TokenStream::_new(imp::TokenStream::new())
219 }
220
221 /// Checks if this `TokenStream` is empty.
222 pub fn is_empty(&self) -> bool {
223 self.inner.is_empty()
224 }
225}
226
227/// `TokenStream::default()` returns an empty stream,
228/// i.e. this is equivalent with `TokenStream::new()`.
229impl Default for TokenStream {
230 fn default() -> Self {
231 TokenStream::new()
232 }
233}
234
235/// Attempts to break the string into tokens and parse those tokens into a token
236/// stream.
237///
238/// May fail for a number of reasons, for example, if the string contains
239/// unbalanced delimiters or characters not existing in the language.
240///
241/// NOTE: Some errors may cause panics instead of returning `LexError`. We
242/// reserve the right to change these errors into `LexError`s later.
243impl FromStr for TokenStream {
244 type Err = LexError;
245
246 fn from_str(src: &str) -> Result<TokenStream, LexError> {
247 match imp::TokenStream::from_str_checked(src) {
248 Ok(tokens) => Ok(TokenStream::_new(tokens)),
249 Err(lex) => Err(LexError {
250 inner: lex,
251 _marker: MARKER,
252 }),
253 }
254 }
255}
256
257#[cfg(feature = "proc-macro")]
258#[cfg_attr(docsrs, doc(cfg(feature = "proc-macro")))]
259impl From<proc_macro::TokenStream> for TokenStream {
260 fn from(inner: proc_macro::TokenStream) -> Self {
261 TokenStream::_new(imp::TokenStream::from(inner))
262 }
263}
264
265#[cfg(feature = "proc-macro")]
266#[cfg_attr(docsrs, doc(cfg(feature = "proc-macro")))]
267impl From<TokenStream> for proc_macro::TokenStream {
268 fn from(inner: TokenStream) -> Self {
269 proc_macro::TokenStream::from(inner.inner)
270 }
271}
272
273impl From<TokenTree> for TokenStream {
274 fn from(token: TokenTree) -> Self {
275 TokenStream::_new(imp::TokenStream::from(token))
276 }
277}
278
279impl Extend<TokenTree> for TokenStream {
280 fn extend<I: IntoIterator<Item = TokenTree>>(&mut self, streams: I) {
281 self.inner.extend(streams);
282 }
283}
284
285impl Extend<TokenStream> for TokenStream {
286 fn extend<I: IntoIterator<Item = TokenStream>>(&mut self, streams: I) {
287 self.inner
288 .extend(streams.into_iter().map(|stream| stream.inner));
289 }
290}
291
292/// Collects a number of token trees into a single stream.
293impl FromIterator<TokenTree> for TokenStream {
294 fn from_iter<I: IntoIterator<Item = TokenTree>>(streams: I) -> Self {
295 TokenStream::_new(streams.into_iter().collect())
296 }
297}
298impl FromIterator<TokenStream> for TokenStream {
299 fn from_iter<I: IntoIterator<Item = TokenStream>>(streams: I) -> Self {
300 TokenStream::_new(streams.into_iter().map(|i| i.inner).collect())
301 }
302}
303
304/// Prints the token stream as a string that is supposed to be losslessly
305/// convertible back into the same token stream (modulo spans), except for
306/// possibly `TokenTree::Group`s with `Delimiter::None` delimiters and negative
307/// numeric literals.
308impl Display for TokenStream {
309 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
310 Display::fmt(&self.inner, f)
311 }
312}
313
314/// Prints token in a form convenient for debugging.
315impl Debug for TokenStream {
316 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
317 Debug::fmt(&self.inner, f)
318 }
319}
320
321impl LexError {
322 pub fn span(&self) -> Span {
323 Span::_new(self.inner.span())
324 }
325}
326
327impl Debug for LexError {
328 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
329 Debug::fmt(&self.inner, f)
330 }
331}
332
333impl Display for LexError {
334 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
335 Display::fmt(&self.inner, f)
336 }
337}
338
339impl Error for LexError {}
340
341/// The source file of a given `Span`.
342///
343/// This type is semver exempt and not exposed by default.
344#[cfg(all(procmacro2_semver_exempt, any(not(wrap_proc_macro), super_unstable)))]
345#[cfg_attr(docsrs, doc(cfg(procmacro2_semver_exempt)))]
346#[derive(Clone, PartialEq, Eq)]
347pub struct SourceFile {
348 inner: imp::SourceFile,
349 _marker: ProcMacroAutoTraits,
350}
351
352#[cfg(all(procmacro2_semver_exempt, any(not(wrap_proc_macro), super_unstable)))]
353impl SourceFile {
354 fn _new(inner: imp::SourceFile) -> Self {
355 SourceFile {
356 inner,
357 _marker: MARKER,
358 }
359 }
360
361 /// Get the path to this source file.
362 ///
363 /// ### Note
364 ///
365 /// If the code span associated with this `SourceFile` was generated by an
366 /// external macro, this may not be an actual path on the filesystem. Use
367 /// [`is_real`] to check.
368 ///
369 /// Also note that even if `is_real` returns `true`, if
370 /// `--remap-path-prefix` was passed on the command line, the path as given
371 /// may not actually be valid.
372 ///
373 /// [`is_real`]: #method.is_real
374 pub fn path(&self) -> PathBuf {
375 self.inner.path()
376 }
377
378 /// Returns `true` if this source file is a real source file, and not
379 /// generated by an external macro's expansion.
380 pub fn is_real(&self) -> bool {
381 self.inner.is_real()
382 }
383}
384
385#[cfg(all(procmacro2_semver_exempt, any(not(wrap_proc_macro), super_unstable)))]
386impl Debug for SourceFile {
387 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
388 Debug::fmt(&self.inner, f)
389 }
390}
391
392/// A region of source code, along with macro expansion information.
393#[derive(Copy, Clone)]
394pub struct Span {
395 inner: imp::Span,
396 _marker: ProcMacroAutoTraits,
397}
398
399impl Span {
400 fn _new(inner: imp::Span) -> Self {
401 Span {
402 inner,
403 _marker: MARKER,
404 }
405 }
406
407 fn _new_fallback(inner: fallback::Span) -> Self {
408 Span {
409 inner: imp::Span::from(inner),
410 _marker: MARKER,
411 }
412 }
413
414 /// The span of the invocation of the current procedural macro.
415 ///
416 /// Identifiers created with this span will be resolved as if they were
417 /// written directly at the macro call location (call-site hygiene) and
418 /// other code at the macro call site will be able to refer to them as well.
419 pub fn call_site() -> Self {
420 Span::_new(imp::Span::call_site())
421 }
422
423 /// The span located at the invocation of the procedural macro, but with
424 /// local variables, labels, and `$crate` resolved at the definition site
425 /// of the macro. This is the same hygiene behavior as `macro_rules`.
426 pub fn mixed_site() -> Self {
427 Span::_new(imp::Span::mixed_site())
428 }
429
430 /// A span that resolves at the macro definition site.
431 ///
432 /// This method is semver exempt and not exposed by default.
433 #[cfg(procmacro2_semver_exempt)]
434 #[cfg_attr(docsrs, doc(cfg(procmacro2_semver_exempt)))]
435 pub fn def_site() -> Self {
436 Span::_new(imp::Span::def_site())
437 }
438
439 /// Creates a new span with the same line/column information as `self` but
440 /// that resolves symbols as though it were at `other`.
441 pub fn resolved_at(&self, other: Span) -> Span {
442 Span::_new(self.inner.resolved_at(other.inner))
443 }
444
445 /// Creates a new span with the same name resolution behavior as `self` but
446 /// with the line/column information of `other`.
447 pub fn located_at(&self, other: Span) -> Span {
448 Span::_new(self.inner.located_at(other.inner))
449 }
450
451 /// Convert `proc_macro2::Span` to `proc_macro::Span`.
452 ///
453 /// This method is available when building with a nightly compiler, or when
454 /// building with rustc 1.29+ *without* semver exempt features.
455 ///
456 /// # Panics
457 ///
458 /// Panics if called from outside of a procedural macro. Unlike
459 /// `proc_macro2::Span`, the `proc_macro::Span` type can only exist within
460 /// the context of a procedural macro invocation.
461 #[cfg(wrap_proc_macro)]
462 pub fn unwrap(self) -> proc_macro::Span {
463 self.inner.unwrap()
464 }
465
466 // Soft deprecated. Please use Span::unwrap.
467 #[cfg(wrap_proc_macro)]
468 #[doc(hidden)]
469 pub fn unstable(self) -> proc_macro::Span {
470 self.unwrap()
471 }
472
473 /// The original source file into which this span points.
474 ///
475 /// This method is semver exempt and not exposed by default.
476 #[cfg(all(procmacro2_semver_exempt, any(not(wrap_proc_macro), super_unstable)))]
477 #[cfg_attr(docsrs, doc(cfg(procmacro2_semver_exempt)))]
478 pub fn source_file(&self) -> SourceFile {
479 SourceFile::_new(self.inner.source_file())
480 }
481
482 /// Returns the span's byte position range in the source file.
483 ///
484 /// This method requires the `"span-locations"` feature to be enabled.
485 ///
486 /// When executing in a procedural macro context, the returned range is only
487 /// accurate if compiled with a nightly toolchain. The stable toolchain does
488 /// not have this information available. When executing outside of a
489 /// procedural macro, such as main.rs or build.rs, the byte range is always
490 /// accurate regardless of toolchain.
491 #[cfg(span_locations)]
492 #[cfg_attr(docsrs, doc(cfg(feature = "span-locations")))]
493 pub fn byte_range(&self) -> Range<usize> {
494 self.inner.byte_range()
495 }
496
497 /// Get the starting line/column in the source file for this span.
498 ///
499 /// This method requires the `"span-locations"` feature to be enabled.
500 ///
501 /// When executing in a procedural macro context, the returned line/column
502 /// are only meaningful if compiled with a nightly toolchain. The stable
503 /// toolchain does not have this information available. When executing
504 /// outside of a procedural macro, such as main.rs or build.rs, the
505 /// line/column are always meaningful regardless of toolchain.
506 #[cfg(span_locations)]
507 #[cfg_attr(docsrs, doc(cfg(feature = "span-locations")))]
508 pub fn start(&self) -> LineColumn {
509 self.inner.start()
510 }
511
512 /// Get the ending line/column in the source file for this span.
513 ///
514 /// This method requires the `"span-locations"` feature to be enabled.
515 ///
516 /// When executing in a procedural macro context, the returned line/column
517 /// are only meaningful if compiled with a nightly toolchain. The stable
518 /// toolchain does not have this information available. When executing
519 /// outside of a procedural macro, such as main.rs or build.rs, the
520 /// line/column are always meaningful regardless of toolchain.
521 #[cfg(span_locations)]
522 #[cfg_attr(docsrs, doc(cfg(feature = "span-locations")))]
523 pub fn end(&self) -> LineColumn {
524 self.inner.end()
525 }
526
527 /// Create a new span encompassing `self` and `other`.
528 ///
529 /// Returns `None` if `self` and `other` are from different files.
530 ///
531 /// Warning: the underlying [`proc_macro::Span::join`] method is
532 /// nightly-only. When called from within a procedural macro not using a
533 /// nightly compiler, this method will always return `None`.
534 pub fn join(&self, other: Span) -> Option<Span> {
535 self.inner.join(other.inner).map(Span::_new)
536 }
537
538 /// Compares two spans to see if they're equal.
539 ///
540 /// This method is semver exempt and not exposed by default.
541 #[cfg(procmacro2_semver_exempt)]
542 #[cfg_attr(docsrs, doc(cfg(procmacro2_semver_exempt)))]
543 pub fn eq(&self, other: &Span) -> bool {
544 self.inner.eq(&other.inner)
545 }
546
547 /// Returns the source text behind a span. This preserves the original
548 /// source code, including spaces and comments. It only returns a result if
549 /// the span corresponds to real source code.
550 ///
551 /// Note: The observable result of a macro should only rely on the tokens
552 /// and not on this source text. The result of this function is a best
553 /// effort to be used for diagnostics only.
554 pub fn source_text(&self) -> Option<String> {
555 self.inner.source_text()
556 }
557}
558
559/// Prints a span in a form convenient for debugging.
560impl Debug for Span {
561 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
562 Debug::fmt(&self.inner, f)
563 }
564}
565
566/// A single token or a delimited sequence of token trees (e.g. `[1, (), ..]`).
567#[derive(Clone)]
568pub enum TokenTree {
569 /// A token stream surrounded by bracket delimiters.
570 Group(Group),
571 /// An identifier.
572 Ident(Ident),
573 /// A single punctuation character (`+`, `,`, `$`, etc.).
574 Punct(Punct),
575 /// A literal character (`'a'`), string (`"hello"`), number (`2.3`), etc.
576 Literal(Literal),
577}
578
579impl TokenTree {
580 /// Returns the span of this tree, delegating to the `span` method of
581 /// the contained token or a delimited stream.
582 pub fn span(&self) -> Span {
583 match self {
584 TokenTree::Group(t) => t.span(),
585 TokenTree::Ident(t) => t.span(),
586 TokenTree::Punct(t) => t.span(),
587 TokenTree::Literal(t) => t.span(),
588 }
589 }
590
591 /// Configures the span for *only this token*.
592 ///
593 /// Note that if this token is a `Group` then this method will not configure
594 /// the span of each of the internal tokens, this will simply delegate to
595 /// the `set_span` method of each variant.
596 pub fn set_span(&mut self, span: Span) {
597 match self {
598 TokenTree::Group(t) => t.set_span(span),
599 TokenTree::Ident(t) => t.set_span(span),
600 TokenTree::Punct(t) => t.set_span(span),
601 TokenTree::Literal(t) => t.set_span(span),
602 }
603 }
604}
605
606impl From<Group> for TokenTree {
607 fn from(g: Group) -> Self {
608 TokenTree::Group(g)
609 }
610}
611
612impl From<Ident> for TokenTree {
613 fn from(g: Ident) -> Self {
614 TokenTree::Ident(g)
615 }
616}
617
618impl From<Punct> for TokenTree {
619 fn from(g: Punct) -> Self {
620 TokenTree::Punct(g)
621 }
622}
623
624impl From<Literal> for TokenTree {
625 fn from(g: Literal) -> Self {
626 TokenTree::Literal(g)
627 }
628}
629
630/// Prints the token tree as a string that is supposed to be losslessly
631/// convertible back into the same token tree (modulo spans), except for
632/// possibly `TokenTree::Group`s with `Delimiter::None` delimiters and negative
633/// numeric literals.
634impl Display for TokenTree {
635 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
636 match self {
637 TokenTree::Group(t) => Display::fmt(t, f),
638 TokenTree::Ident(t) => Display::fmt(t, f),
639 TokenTree::Punct(t) => Display::fmt(t, f),
640 TokenTree::Literal(t) => Display::fmt(t, f),
641 }
642 }
643}
644
645/// Prints token tree in a form convenient for debugging.
646impl Debug for TokenTree {
647 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
648 // Each of these has the name in the struct type in the derived debug,
649 // so don't bother with an extra layer of indirection
650 match self {
651 TokenTree::Group(t) => Debug::fmt(t, f),
652 TokenTree::Ident(t) => {
653 let mut debug = f.debug_struct("Ident");
654 debug.field("sym", &format_args!("{}", t));
655 imp::debug_span_field_if_nontrivial(&mut debug, t.span().inner);
656 debug.finish()
657 }
658 TokenTree::Punct(t) => Debug::fmt(t, f),
659 TokenTree::Literal(t) => Debug::fmt(t, f),
660 }
661 }
662}
663
664/// A delimited token stream.
665///
666/// A `Group` internally contains a `TokenStream` which is surrounded by
667/// `Delimiter`s.
668#[derive(Clone)]
669pub struct Group {
670 inner: imp::Group,
671}
672
673/// Describes how a sequence of token trees is delimited.
674#[derive(Copy, Clone, Debug, Eq, PartialEq)]
675pub enum Delimiter {
676 /// `( ... )`
677 Parenthesis,
678 /// `{ ... }`
679 Brace,
680 /// `[ ... ]`
681 Bracket,
682 /// `∅ ... ∅`
683 ///
684 /// An invisible delimiter, that may, for example, appear around tokens
685 /// coming from a "macro variable" `$var`. It is important to preserve
686 /// operator priorities in cases like `$var * 3` where `$var` is `1 + 2`.
687 /// Invisible delimiters may not survive roundtrip of a token stream through
688 /// a string.
689 ///
690 /// <div class="warning">
691 ///
692 /// Note: rustc currently can ignore the grouping of tokens delimited by `None` in the output
693 /// of a proc_macro. Only `None`-delimited groups created by a macro_rules macro in the input
694 /// of a proc_macro macro are preserved, and only in very specific circumstances.
695 /// Any `None`-delimited groups (re)created by a proc_macro will therefore not preserve
696 /// operator priorities as indicated above. The other `Delimiter` variants should be used
697 /// instead in this context. This is a rustc bug. For details, see
698 /// [rust-lang/rust#67062](https://github.com/rust-lang/rust/issues/67062).
699 ///
700 /// </div>
701 None,
702}
703
704impl Group {
705 fn _new(inner: imp::Group) -> Self {
706 Group { inner }
707 }
708
709 fn _new_fallback(inner: fallback::Group) -> Self {
710 Group {
711 inner: imp::Group::from(inner),
712 }
713 }
714
715 /// Creates a new `Group` with the given delimiter and token stream.
716 ///
717 /// This constructor will set the span for this group to
718 /// `Span::call_site()`. To change the span you can use the `set_span`
719 /// method below.
720 pub fn new(delimiter: Delimiter, stream: TokenStream) -> Self {
721 Group {
722 inner: imp::Group::new(delimiter, stream.inner),
723 }
724 }
725
726 /// Returns the punctuation used as the delimiter for this group: a set of
727 /// parentheses, square brackets, or curly braces.
728 pub fn delimiter(&self) -> Delimiter {
729 self.inner.delimiter()
730 }
731
732 /// Returns the `TokenStream` of tokens that are delimited in this `Group`.
733 ///
734 /// Note that the returned token stream does not include the delimiter
735 /// returned above.
736 pub fn stream(&self) -> TokenStream {
737 TokenStream::_new(self.inner.stream())
738 }
739
740 /// Returns the span for the delimiters of this token stream, spanning the
741 /// entire `Group`.
742 ///
743 /// ```text
744 /// pub fn span(&self) -> Span {
745 /// ^^^^^^^
746 /// ```
747 pub fn span(&self) -> Span {
748 Span::_new(self.inner.span())
749 }
750
751 /// Returns the span pointing to the opening delimiter of this group.
752 ///
753 /// ```text
754 /// pub fn span_open(&self) -> Span {
755 /// ^
756 /// ```
757 pub fn span_open(&self) -> Span {
758 Span::_new(self.inner.span_open())
759 }
760
761 /// Returns the span pointing to the closing delimiter of this group.
762 ///
763 /// ```text
764 /// pub fn span_close(&self) -> Span {
765 /// ^
766 /// ```
767 pub fn span_close(&self) -> Span {
768 Span::_new(self.inner.span_close())
769 }
770
771 /// Returns an object that holds this group's `span_open()` and
772 /// `span_close()` together (in a more compact representation than holding
773 /// those 2 spans individually).
774 pub fn delim_span(&self) -> DelimSpan {
775 DelimSpan::new(&self.inner)
776 }
777
778 /// Configures the span for this `Group`'s delimiters, but not its internal
779 /// tokens.
780 ///
781 /// This method will **not** set the span of all the internal tokens spanned
782 /// by this group, but rather it will only set the span of the delimiter
783 /// tokens at the level of the `Group`.
784 pub fn set_span(&mut self, span: Span) {
785 self.inner.set_span(span.inner);
786 }
787}
788
789/// Prints the group as a string that should be losslessly convertible back
790/// into the same group (modulo spans), except for possibly `TokenTree::Group`s
791/// with `Delimiter::None` delimiters.
792impl Display for Group {
793 fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
794 Display::fmt(&self.inner, formatter)
795 }
796}
797
798impl Debug for Group {
799 fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
800 Debug::fmt(&self.inner, formatter)
801 }
802}
803
804/// A `Punct` is a single punctuation character like `+`, `-` or `#`.
805///
806/// Multicharacter operators like `+=` are represented as two instances of
807/// `Punct` with different forms of `Spacing` returned.
808#[derive(Clone)]
809pub struct Punct {
810 ch: char,
811 spacing: Spacing,
812 span: Span,
813}
814
815/// Whether a `Punct` is followed immediately by another `Punct` or followed by
816/// another token or whitespace.
817#[derive(Copy, Clone, Debug, Eq, PartialEq)]
818pub enum Spacing {
819 /// E.g. `+` is `Alone` in `+ =`, `+ident` or `+()`.
820 Alone,
821 /// E.g. `+` is `Joint` in `+=` or `'` is `Joint` in `'#`.
822 ///
823 /// Additionally, single quote `'` can join with identifiers to form
824 /// lifetimes `'ident`.
825 Joint,
826}
827
828impl Punct {
829 /// Creates a new `Punct` from the given character and spacing.
830 ///
831 /// The `ch` argument must be a valid punctuation character permitted by the
832 /// language, otherwise the function will panic.
833 ///
834 /// The returned `Punct` will have the default span of `Span::call_site()`
835 /// which can be further configured with the `set_span` method below.
836 pub fn new(ch: char, spacing: Spacing) -> Self {
837 if let '!' | '#' | '$' | '%' | '&' | '\'' | '*' | '+' | ',' | '-' | '.' | '/' | ':' | ';'
838 | '<' | '=' | '>' | '?' | '@' | '^' | '|' | '~' = ch
839 {
840 Punct {
841 ch,
842 spacing,
843 span: Span::call_site(),
844 }
845 } else {
846 panic!("unsupported proc macro punctuation character {:?}", ch);
847 }
848 }
849
850 /// Returns the value of this punctuation character as `char`.
851 pub fn as_char(&self) -> char {
852 self.ch
853 }
854
855 /// Returns the spacing of this punctuation character, indicating whether
856 /// it's immediately followed by another `Punct` in the token stream, so
857 /// they can potentially be combined into a multicharacter operator
858 /// (`Joint`), or it's followed by some other token or whitespace (`Alone`)
859 /// so the operator has certainly ended.
860 pub fn spacing(&self) -> Spacing {
861 self.spacing
862 }
863
864 /// Returns the span for this punctuation character.
865 pub fn span(&self) -> Span {
866 self.span
867 }
868
869 /// Configure the span for this punctuation character.
870 pub fn set_span(&mut self, span: Span) {
871 self.span = span;
872 }
873}
874
875/// Prints the punctuation character as a string that should be losslessly
876/// convertible back into the same character.
877impl Display for Punct {
878 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
879 Display::fmt(&self.ch, f)
880 }
881}
882
883impl Debug for Punct {
884 fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
885 let mut debug = fmt.debug_struct("Punct");
886 debug.field("char", &self.ch);
887 debug.field("spacing", &self.spacing);
888 imp::debug_span_field_if_nontrivial(&mut debug, self.span.inner);
889 debug.finish()
890 }
891}
892
893/// A word of Rust code, which may be a keyword or legal variable name.
894///
895/// An identifier consists of at least one Unicode code point, the first of
896/// which has the XID_Start property and the rest of which have the XID_Continue
897/// property.
898///
899/// - The empty string is not an identifier. Use `Option<Ident>`.
900/// - A lifetime is not an identifier. Use `syn::Lifetime` instead.
901///
902/// An identifier constructed with `Ident::new` is permitted to be a Rust
903/// keyword, though parsing one through its [`Parse`] implementation rejects
904/// Rust keywords. Use `input.call(Ident::parse_any)` when parsing to match the
905/// behaviour of `Ident::new`.
906///
907/// [`Parse`]: https://docs.rs/syn/2.0/syn/parse/trait.Parse.html
908///
909/// # Examples
910///
911/// A new ident can be created from a string using the `Ident::new` function.
912/// A span must be provided explicitly which governs the name resolution
913/// behavior of the resulting identifier.
914///
915/// ```
916/// use proc_macro2::{Ident, Span};
917///
918/// fn main() {
919/// let call_ident = Ident::new("calligraphy", Span::call_site());
920///
921/// println!("{}", call_ident);
922/// }
923/// ```
924///
925/// An ident can be interpolated into a token stream using the `quote!` macro.
926///
927/// ```
928/// use proc_macro2::{Ident, Span};
929/// use quote::quote;
930///
931/// fn main() {
932/// let ident = Ident::new("demo", Span::call_site());
933///
934/// // Create a variable binding whose name is this ident.
935/// let expanded = quote! { let #ident = 10; };
936///
937/// // Create a variable binding with a slightly different name.
938/// let temp_ident = Ident::new(&format!("new_{}", ident), Span::call_site());
939/// let expanded = quote! { let #temp_ident = 10; };
940/// }
941/// ```
942///
943/// A string representation of the ident is available through the `to_string()`
944/// method.
945///
946/// ```
947/// # use proc_macro2::{Ident, Span};
948/// #
949/// # let ident = Ident::new("another_identifier", Span::call_site());
950/// #
951/// // Examine the ident as a string.
952/// let ident_string = ident.to_string();
953/// if ident_string.len() > 60 {
954/// println!("Very long identifier: {}", ident_string)
955/// }
956/// ```
957#[derive(Clone)]
958pub struct Ident {
959 inner: imp::Ident,
960 _marker: ProcMacroAutoTraits,
961}
962
963impl Ident {
964 fn _new(inner: imp::Ident) -> Self {
965 Ident {
966 inner,
967 _marker: MARKER,
968 }
969 }
970
971 fn _new_fallback(inner: fallback::Ident) -> Self {
972 Ident {
973 inner: imp::Ident::from(inner),
974 _marker: MARKER,
975 }
976 }
977
978 /// Creates a new `Ident` with the given `string` as well as the specified
979 /// `span`.
980 ///
981 /// The `string` argument must be a valid identifier permitted by the
982 /// language, otherwise the function will panic.
983 ///
984 /// Note that `span`, currently in rustc, configures the hygiene information
985 /// for this identifier.
986 ///
987 /// As of this time `Span::call_site()` explicitly opts-in to "call-site"
988 /// hygiene meaning that identifiers created with this span will be resolved
989 /// as if they were written directly at the location of the macro call, and
990 /// other code at the macro call site will be able to refer to them as well.
991 ///
992 /// Later spans like `Span::def_site()` will allow to opt-in to
993 /// "definition-site" hygiene meaning that identifiers created with this
994 /// span will be resolved at the location of the macro definition and other
995 /// code at the macro call site will not be able to refer to them.
996 ///
997 /// Due to the current importance of hygiene this constructor, unlike other
998 /// tokens, requires a `Span` to be specified at construction.
999 ///
1000 /// # Panics
1001 ///
1002 /// Panics if the input string is neither a keyword nor a legal variable
1003 /// name. If you are not sure whether the string contains an identifier and
1004 /// need to handle an error case, use
1005 /// <a href="https://docs.rs/syn/2.0/syn/fn.parse_str.html"><code
1006 /// style="padding-right:0;">syn::parse_str</code></a><code
1007 /// style="padding-left:0;">::<Ident></code>
1008 /// rather than `Ident::new`.
1009 #[track_caller]
1010 pub fn new(string: &str, span: Span) -> Self {
1011 Ident::_new(imp::Ident::new_checked(string, span.inner))
1012 }
1013
1014 /// Same as `Ident::new`, but creates a raw identifier (`r#ident`). The
1015 /// `string` argument must be a valid identifier permitted by the language
1016 /// (including keywords, e.g. `fn`). Keywords which are usable in path
1017 /// segments (e.g. `self`, `super`) are not supported, and will cause a
1018 /// panic.
1019 #[track_caller]
1020 pub fn new_raw(string: &str, span: Span) -> Self {
1021 Ident::_new(imp::Ident::new_raw_checked(string, span.inner))
1022 }
1023
1024 /// Returns the span of this `Ident`.
1025 pub fn span(&self) -> Span {
1026 Span::_new(self.inner.span())
1027 }
1028
1029 /// Configures the span of this `Ident`, possibly changing its hygiene
1030 /// context.
1031 pub fn set_span(&mut self, span: Span) {
1032 self.inner.set_span(span.inner);
1033 }
1034}
1035
1036impl PartialEq for Ident {
1037 fn eq(&self, other: &Ident) -> bool {
1038 self.inner == other.inner
1039 }
1040}
1041
1042impl<T> PartialEq<T> for Ident
1043where
1044 T: ?Sized + AsRef<str>,
1045{
1046 fn eq(&self, other: &T) -> bool {
1047 self.inner == other
1048 }
1049}
1050
1051impl Eq for Ident {}
1052
1053impl PartialOrd for Ident {
1054 fn partial_cmp(&self, other: &Ident) -> Option<Ordering> {
1055 Some(self.cmp(other))
1056 }
1057}
1058
1059impl Ord for Ident {
1060 fn cmp(&self, other: &Ident) -> Ordering {
1061 self.to_string().cmp(&other.to_string())
1062 }
1063}
1064
1065impl Hash for Ident {
1066 fn hash<H: Hasher>(&self, hasher: &mut H) {
1067 self.to_string().hash(hasher);
1068 }
1069}
1070
1071/// Prints the identifier as a string that should be losslessly convertible back
1072/// into the same identifier.
1073impl Display for Ident {
1074 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1075 Display::fmt(&self.inner, f)
1076 }
1077}
1078
1079impl Debug for Ident {
1080 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1081 Debug::fmt(&self.inner, f)
1082 }
1083}
1084
1085/// A literal string (`"hello"`), byte string (`b"hello"`), character (`'a'`),
1086/// byte character (`b'a'`), an integer or floating point number with or without
1087/// a suffix (`1`, `1u8`, `2.3`, `2.3f32`).
1088///
1089/// Boolean literals like `true` and `false` do not belong here, they are
1090/// `Ident`s.
1091#[derive(Clone)]
1092pub struct Literal {
1093 inner: imp::Literal,
1094 _marker: ProcMacroAutoTraits,
1095}
1096
1097macro_rules! suffixed_int_literals {
1098 ($($name:ident => $kind:ident,)*) => ($(
1099 /// Creates a new suffixed integer literal with the specified value.
1100 ///
1101 /// This function will create an integer like `1u32` where the integer
1102 /// value specified is the first part of the token and the integral is
1103 /// also suffixed at the end. Literals created from negative numbers may
1104 /// not survive roundtrips through `TokenStream` or strings and may be
1105 /// broken into two tokens (`-` and positive literal).
1106 ///
1107 /// Literals created through this method have the `Span::call_site()`
1108 /// span by default, which can be configured with the `set_span` method
1109 /// below.
1110 pub fn $name(n: $kind) -> Literal {
1111 Literal::_new(imp::Literal::$name(n))
1112 }
1113 )*)
1114}
1115
1116macro_rules! unsuffixed_int_literals {
1117 ($($name:ident => $kind:ident,)*) => ($(
1118 /// Creates a new unsuffixed integer literal with the specified value.
1119 ///
1120 /// This function will create an integer like `1` where the integer
1121 /// value specified is the first part of the token. No suffix is
1122 /// specified on this token, meaning that invocations like
1123 /// `Literal::i8_unsuffixed(1)` are equivalent to
1124 /// `Literal::u32_unsuffixed(1)`. Literals created from negative numbers
1125 /// may not survive roundtrips through `TokenStream` or strings and may
1126 /// be broken into two tokens (`-` and positive literal).
1127 ///
1128 /// Literals created through this method have the `Span::call_site()`
1129 /// span by default, which can be configured with the `set_span` method
1130 /// below.
1131 pub fn $name(n: $kind) -> Literal {
1132 Literal::_new(imp::Literal::$name(n))
1133 }
1134 )*)
1135}
1136
1137impl Literal {
1138 fn _new(inner: imp::Literal) -> Self {
1139 Literal {
1140 inner,
1141 _marker: MARKER,
1142 }
1143 }
1144
1145 fn _new_fallback(inner: fallback::Literal) -> Self {
1146 Literal {
1147 inner: imp::Literal::from(inner),
1148 _marker: MARKER,
1149 }
1150 }
1151
1152 suffixed_int_literals! {
1153 u8_suffixed => u8,
1154 u16_suffixed => u16,
1155 u32_suffixed => u32,
1156 u64_suffixed => u64,
1157 u128_suffixed => u128,
1158 usize_suffixed => usize,
1159 i8_suffixed => i8,
1160 i16_suffixed => i16,
1161 i32_suffixed => i32,
1162 i64_suffixed => i64,
1163 i128_suffixed => i128,
1164 isize_suffixed => isize,
1165 }
1166
1167 unsuffixed_int_literals! {
1168 u8_unsuffixed => u8,
1169 u16_unsuffixed => u16,
1170 u32_unsuffixed => u32,
1171 u64_unsuffixed => u64,
1172 u128_unsuffixed => u128,
1173 usize_unsuffixed => usize,
1174 i8_unsuffixed => i8,
1175 i16_unsuffixed => i16,
1176 i32_unsuffixed => i32,
1177 i64_unsuffixed => i64,
1178 i128_unsuffixed => i128,
1179 isize_unsuffixed => isize,
1180 }
1181
1182 /// Creates a new unsuffixed floating-point literal.
1183 ///
1184 /// This constructor is similar to those like `Literal::i8_unsuffixed` where
1185 /// the float's value is emitted directly into the token but no suffix is
1186 /// used, so it may be inferred to be a `f64` later in the compiler.
1187 /// Literals created from negative numbers may not survive round-trips
1188 /// through `TokenStream` or strings and may be broken into two tokens (`-`
1189 /// and positive literal).
1190 ///
1191 /// # Panics
1192 ///
1193 /// This function requires that the specified float is finite, for example
1194 /// if it is infinity or NaN this function will panic.
1195 pub fn f64_unsuffixed(f: f64) -> Literal {
1196 assert!(f.is_finite());
1197 Literal::_new(imp::Literal::f64_unsuffixed(f))
1198 }
1199
1200 /// Creates a new suffixed floating-point literal.
1201 ///
1202 /// This constructor will create a literal like `1.0f64` where the value
1203 /// specified is the preceding part of the token and `f64` is the suffix of
1204 /// the token. This token will always be inferred to be an `f64` in the
1205 /// compiler. Literals created from negative numbers may not survive
1206 /// round-trips through `TokenStream` or strings and may be broken into two
1207 /// tokens (`-` and positive literal).
1208 ///
1209 /// # Panics
1210 ///
1211 /// This function requires that the specified float is finite, for example
1212 /// if it is infinity or NaN this function will panic.
1213 pub fn f64_suffixed(f: f64) -> Literal {
1214 assert!(f.is_finite());
1215 Literal::_new(imp::Literal::f64_suffixed(f))
1216 }
1217
1218 /// Creates a new unsuffixed floating-point literal.
1219 ///
1220 /// This constructor is similar to those like `Literal::i8_unsuffixed` where
1221 /// the float's value is emitted directly into the token but no suffix is
1222 /// used, so it may be inferred to be a `f64` later in the compiler.
1223 /// Literals created from negative numbers may not survive round-trips
1224 /// through `TokenStream` or strings and may be broken into two tokens (`-`
1225 /// and positive literal).
1226 ///
1227 /// # Panics
1228 ///
1229 /// This function requires that the specified float is finite, for example
1230 /// if it is infinity or NaN this function will panic.
1231 pub fn f32_unsuffixed(f: f32) -> Literal {
1232 assert!(f.is_finite());
1233 Literal::_new(imp::Literal::f32_unsuffixed(f))
1234 }
1235
1236 /// Creates a new suffixed floating-point literal.
1237 ///
1238 /// This constructor will create a literal like `1.0f32` where the value
1239 /// specified is the preceding part of the token and `f32` is the suffix of
1240 /// the token. This token will always be inferred to be an `f32` in the
1241 /// compiler. Literals created from negative numbers may not survive
1242 /// round-trips through `TokenStream` or strings and may be broken into two
1243 /// tokens (`-` and positive literal).
1244 ///
1245 /// # Panics
1246 ///
1247 /// This function requires that the specified float is finite, for example
1248 /// if it is infinity or NaN this function will panic.
1249 pub fn f32_suffixed(f: f32) -> Literal {
1250 assert!(f.is_finite());
1251 Literal::_new(imp::Literal::f32_suffixed(f))
1252 }
1253
1254 /// String literal.
1255 pub fn string(string: &str) -> Literal {
1256 Literal::_new(imp::Literal::string(string))
1257 }
1258
1259 /// Character literal.
1260 pub fn character(ch: char) -> Literal {
1261 Literal::_new(imp::Literal::character(ch))
1262 }
1263
1264 /// Byte character literal.
1265 pub fn byte_character(byte: u8) -> Literal {
1266 Literal::_new(imp::Literal::byte_character(byte))
1267 }
1268
1269 /// Byte string literal.
1270 pub fn byte_string(bytes: &[u8]) -> Literal {
1271 Literal::_new(imp::Literal::byte_string(bytes))
1272 }
1273
1274 /// C string literal.
1275 pub fn c_string(string: &CStr) -> Literal {
1276 Literal::_new(imp::Literal::c_string(string))
1277 }
1278
1279 /// Returns the span encompassing this literal.
1280 pub fn span(&self) -> Span {
1281 Span::_new(self.inner.span())
1282 }
1283
1284 /// Configures the span associated for this literal.
1285 pub fn set_span(&mut self, span: Span) {
1286 self.inner.set_span(span.inner);
1287 }
1288
1289 /// Returns a `Span` that is a subset of `self.span()` containing only
1290 /// the source bytes in range `range`. Returns `None` if the would-be
1291 /// trimmed span is outside the bounds of `self`.
1292 ///
1293 /// Warning: the underlying [`proc_macro::Literal::subspan`] method is
1294 /// nightly-only. When called from within a procedural macro not using a
1295 /// nightly compiler, this method will always return `None`.
1296 pub fn subspan<R: RangeBounds<usize>>(&self, range: R) -> Option<Span> {
1297 self.inner.subspan(range).map(Span::_new)
1298 }
1299
1300 // Intended for the `quote!` macro to use when constructing a proc-macro2
1301 // token out of a macro_rules $:literal token, which is already known to be
1302 // a valid literal. This avoids reparsing/validating the literal's string
1303 // representation. This is not public API other than for quote.
1304 #[doc(hidden)]
1305 pub unsafe fn from_str_unchecked(repr: &str) -> Self {
1306 Literal::_new(unsafe { imp::Literal::from_str_unchecked(repr) })
1307 }
1308}
1309
1310impl FromStr for Literal {
1311 type Err = LexError;
1312
1313 fn from_str(repr: &str) -> Result<Self, LexError> {
1314 match imp::Literal::from_str_checked(repr) {
1315 Ok(lit) => Ok(Literal::_new(lit)),
1316 Err(lex) => Err(LexError {
1317 inner: lex,
1318 _marker: MARKER,
1319 }),
1320 }
1321 }
1322}
1323
1324impl Debug for Literal {
1325 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1326 Debug::fmt(&self.inner, f)
1327 }
1328}
1329
1330impl Display for Literal {
1331 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1332 Display::fmt(&self.inner, f)
1333 }
1334}
1335
1336/// Public implementation details for the `TokenStream` type, such as iterators.
1337pub mod token_stream {
1338 use crate::marker::{ProcMacroAutoTraits, MARKER};
1339 use crate::{imp, TokenTree};
1340 use core::fmt::{self, Debug};
1341
1342 pub use crate::TokenStream;
1343
1344 /// An iterator over `TokenStream`'s `TokenTree`s.
1345 ///
1346 /// The iteration is "shallow", e.g. the iterator doesn't recurse into
1347 /// delimited groups, and returns whole groups as token trees.
1348 #[derive(Clone)]
1349 pub struct IntoIter {
1350 inner: imp::TokenTreeIter,
1351 _marker: ProcMacroAutoTraits,
1352 }
1353
1354 impl Iterator for IntoIter {
1355 type Item = TokenTree;
1356
1357 fn next(&mut self) -> Option<TokenTree> {
1358 self.inner.next()
1359 }
1360
1361 fn size_hint(&self) -> (usize, Option<usize>) {
1362 self.inner.size_hint()
1363 }
1364 }
1365
1366 impl Debug for IntoIter {
1367 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1368 f.write_str("TokenStream ")?;
1369 f.debug_list().entries(self.clone()).finish()
1370 }
1371 }
1372
1373 impl IntoIterator for TokenStream {
1374 type Item = TokenTree;
1375 type IntoIter = IntoIter;
1376
1377 fn into_iter(self) -> IntoIter {
1378 IntoIter {
1379 inner: self.inner.into_iter(),
1380 _marker: MARKER,
1381 }
1382 }
1383 }
1384}