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-macro2/1.0.95")]
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: TokenStream) => Ok(TokenStream::_new(inner:tokens)),
249 Err(lex: LexError) => 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(inner: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(inner: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(iter: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(iter:streams.into_iter().map(|stream: TokenStream| 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(inner: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(inner:streams.into_iter().map(|i: TokenStream| 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/// A region of source code, along with macro expansion information.
342#[derive(Copy, Clone)]
343pub struct Span {
344 inner: imp::Span,
345 _marker: ProcMacroAutoTraits,
346}
347
348impl Span {
349 fn _new(inner: imp::Span) -> Self {
350 Span {
351 inner,
352 _marker: MARKER,
353 }
354 }
355
356 fn _new_fallback(inner: fallback::Span) -> Self {
357 Span {
358 inner: imp::Span::from(inner),
359 _marker: MARKER,
360 }
361 }
362
363 /// The span of the invocation of the current procedural macro.
364 ///
365 /// Identifiers created with this span will be resolved as if they were
366 /// written directly at the macro call location (call-site hygiene) and
367 /// other code at the macro call site will be able to refer to them as well.
368 pub fn call_site() -> Self {
369 Span::_new(imp::Span::call_site())
370 }
371
372 /// The span located at the invocation of the procedural macro, but with
373 /// local variables, labels, and `$crate` resolved at the definition site
374 /// of the macro. This is the same hygiene behavior as `macro_rules`.
375 pub fn mixed_site() -> Self {
376 Span::_new(imp::Span::mixed_site())
377 }
378
379 /// A span that resolves at the macro definition site.
380 ///
381 /// This method is semver exempt and not exposed by default.
382 #[cfg(procmacro2_semver_exempt)]
383 #[cfg_attr(docsrs, doc(cfg(procmacro2_semver_exempt)))]
384 pub fn def_site() -> Self {
385 Span::_new(imp::Span::def_site())
386 }
387
388 /// Creates a new span with the same line/column information as `self` but
389 /// that resolves symbols as though it were at `other`.
390 pub fn resolved_at(&self, other: Span) -> Span {
391 Span::_new(self.inner.resolved_at(other.inner))
392 }
393
394 /// Creates a new span with the same name resolution behavior as `self` but
395 /// with the line/column information of `other`.
396 pub fn located_at(&self, other: Span) -> Span {
397 Span::_new(self.inner.located_at(other.inner))
398 }
399
400 /// Convert `proc_macro2::Span` to `proc_macro::Span`.
401 ///
402 /// This method is available when building with a nightly compiler, or when
403 /// building with rustc 1.29+ *without* semver exempt features.
404 ///
405 /// # Panics
406 ///
407 /// Panics if called from outside of a procedural macro. Unlike
408 /// `proc_macro2::Span`, the `proc_macro::Span` type can only exist within
409 /// the context of a procedural macro invocation.
410 #[cfg(wrap_proc_macro)]
411 pub fn unwrap(self) -> proc_macro::Span {
412 self.inner.unwrap()
413 }
414
415 // Soft deprecated. Please use Span::unwrap.
416 #[cfg(wrap_proc_macro)]
417 #[doc(hidden)]
418 pub fn unstable(self) -> proc_macro::Span {
419 self.unwrap()
420 }
421
422 /// Returns the span's byte position range in the source file.
423 ///
424 /// This method requires the `"span-locations"` feature to be enabled.
425 ///
426 /// When executing in a procedural macro context, the returned range is only
427 /// accurate if compiled with a nightly toolchain. The stable toolchain does
428 /// not have this information available. When executing outside of a
429 /// procedural macro, such as main.rs or build.rs, the byte range is always
430 /// accurate regardless of toolchain.
431 #[cfg(span_locations)]
432 #[cfg_attr(docsrs, doc(cfg(feature = "span-locations")))]
433 pub fn byte_range(&self) -> Range<usize> {
434 self.inner.byte_range()
435 }
436
437 /// Get the starting line/column in the source file for this span.
438 ///
439 /// This method requires the `"span-locations"` feature to be enabled.
440 ///
441 /// When executing in a procedural macro context, the returned line/column
442 /// are only meaningful if compiled with a nightly toolchain. The stable
443 /// toolchain does not have this information available. When executing
444 /// outside of a procedural macro, such as main.rs or build.rs, the
445 /// line/column are always meaningful regardless of toolchain.
446 #[cfg(span_locations)]
447 #[cfg_attr(docsrs, doc(cfg(feature = "span-locations")))]
448 pub fn start(&self) -> LineColumn {
449 self.inner.start()
450 }
451
452 /// Get the ending line/column in the source file for this span.
453 ///
454 /// This method requires the `"span-locations"` feature to be enabled.
455 ///
456 /// When executing in a procedural macro context, the returned line/column
457 /// are only meaningful if compiled with a nightly toolchain. The stable
458 /// toolchain does not have this information available. When executing
459 /// outside of a procedural macro, such as main.rs or build.rs, the
460 /// line/column are always meaningful regardless of toolchain.
461 #[cfg(span_locations)]
462 #[cfg_attr(docsrs, doc(cfg(feature = "span-locations")))]
463 pub fn end(&self) -> LineColumn {
464 self.inner.end()
465 }
466
467 /// The path to the source file in which this span occurs, for display
468 /// purposes.
469 ///
470 /// This might not correspond to a valid file system path. It might be
471 /// remapped, or might be an artificial path such as `"<macro expansion>"`.
472 ///
473 /// This method is semver exempt and not exposed by default.
474 #[cfg(all(procmacro2_semver_exempt, any(not(wrap_proc_macro), super_unstable)))]
475 #[cfg_attr(docsrs, doc(cfg(procmacro2_semver_exempt)))]
476 pub fn file(&self) -> String {
477 self.inner.file()
478 }
479
480 /// The path to the source file in which this span occurs on disk.
481 ///
482 /// This is the actual path on disk. It is unaffected by path remapping.
483 ///
484 /// This path should not be embedded in the output of the macro; prefer
485 /// `file()` instead.
486 ///
487 /// This method is semver exempt and not exposed by default.
488 #[cfg(all(procmacro2_semver_exempt, any(not(wrap_proc_macro), super_unstable)))]
489 #[cfg_attr(docsrs, doc(cfg(procmacro2_semver_exempt)))]
490 pub fn local_file(&self) -> Option<PathBuf> {
491 self.inner.local_file()
492 }
493
494 /// Create a new span encompassing `self` and `other`.
495 ///
496 /// Returns `None` if `self` and `other` are from different files.
497 ///
498 /// Warning: the underlying [`proc_macro::Span::join`] method is
499 /// nightly-only. When called from within a procedural macro not using a
500 /// nightly compiler, this method will always return `None`.
501 pub fn join(&self, other: Span) -> Option<Span> {
502 self.inner.join(other.inner).map(Span::_new)
503 }
504
505 /// Compares two spans to see if they're equal.
506 ///
507 /// This method is semver exempt and not exposed by default.
508 #[cfg(procmacro2_semver_exempt)]
509 #[cfg_attr(docsrs, doc(cfg(procmacro2_semver_exempt)))]
510 pub fn eq(&self, other: &Span) -> bool {
511 self.inner.eq(&other.inner)
512 }
513
514 /// Returns the source text behind a span. This preserves the original
515 /// source code, including spaces and comments. It only returns a result if
516 /// the span corresponds to real source code.
517 ///
518 /// Note: The observable result of a macro should only rely on the tokens
519 /// and not on this source text. The result of this function is a best
520 /// effort to be used for diagnostics only.
521 pub fn source_text(&self) -> Option<String> {
522 self.inner.source_text()
523 }
524}
525
526/// Prints a span in a form convenient for debugging.
527impl Debug for Span {
528 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
529 Debug::fmt(&self.inner, f)
530 }
531}
532
533/// A single token or a delimited sequence of token trees (e.g. `[1, (), ..]`).
534#[derive(Clone)]
535pub enum TokenTree {
536 /// A token stream surrounded by bracket delimiters.
537 Group(Group),
538 /// An identifier.
539 Ident(Ident),
540 /// A single punctuation character (`+`, `,`, `$`, etc.).
541 Punct(Punct),
542 /// A literal character (`'a'`), string (`"hello"`), number (`2.3`), etc.
543 Literal(Literal),
544}
545
546impl TokenTree {
547 /// Returns the span of this tree, delegating to the `span` method of
548 /// the contained token or a delimited stream.
549 pub fn span(&self) -> Span {
550 match self {
551 TokenTree::Group(t) => t.span(),
552 TokenTree::Ident(t) => t.span(),
553 TokenTree::Punct(t) => t.span(),
554 TokenTree::Literal(t) => t.span(),
555 }
556 }
557
558 /// Configures the span for *only this token*.
559 ///
560 /// Note that if this token is a `Group` then this method will not configure
561 /// the span of each of the internal tokens, this will simply delegate to
562 /// the `set_span` method of each variant.
563 pub fn set_span(&mut self, span: Span) {
564 match self {
565 TokenTree::Group(t) => t.set_span(span),
566 TokenTree::Ident(t) => t.set_span(span),
567 TokenTree::Punct(t) => t.set_span(span),
568 TokenTree::Literal(t) => t.set_span(span),
569 }
570 }
571}
572
573impl From<Group> for TokenTree {
574 fn from(g: Group) -> Self {
575 TokenTree::Group(g)
576 }
577}
578
579impl From<Ident> for TokenTree {
580 fn from(g: Ident) -> Self {
581 TokenTree::Ident(g)
582 }
583}
584
585impl From<Punct> for TokenTree {
586 fn from(g: Punct) -> Self {
587 TokenTree::Punct(g)
588 }
589}
590
591impl From<Literal> for TokenTree {
592 fn from(g: Literal) -> Self {
593 TokenTree::Literal(g)
594 }
595}
596
597/// Prints the token tree as a string that is supposed to be losslessly
598/// convertible back into the same token tree (modulo spans), except for
599/// possibly `TokenTree::Group`s with `Delimiter::None` delimiters and negative
600/// numeric literals.
601impl Display for TokenTree {
602 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
603 match self {
604 TokenTree::Group(t: &Group) => Display::fmt(self:t, f),
605 TokenTree::Ident(t: &Ident) => Display::fmt(self:t, f),
606 TokenTree::Punct(t: &Punct) => Display::fmt(self:t, f),
607 TokenTree::Literal(t: &Literal) => Display::fmt(self:t, f),
608 }
609 }
610}
611
612/// Prints token tree in a form convenient for debugging.
613impl Debug for TokenTree {
614 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
615 // Each of these has the name in the struct type in the derived debug,
616 // so don't bother with an extra layer of indirection
617 match self {
618 TokenTree::Group(t: &Group) => Debug::fmt(self:t, f),
619 TokenTree::Ident(t: &Ident) => {
620 let mut debug: DebugStruct<'_, '_> = f.debug_struct(name:"Ident");
621 debug.field(name:"sym", &format_args!("{}", t));
622 imp::debug_span_field_if_nontrivial(&mut debug, span:t.span().inner);
623 debug.finish()
624 }
625 TokenTree::Punct(t: &Punct) => Debug::fmt(self:t, f),
626 TokenTree::Literal(t: &Literal) => Debug::fmt(self:t, f),
627 }
628 }
629}
630
631/// A delimited token stream.
632///
633/// A `Group` internally contains a `TokenStream` which is surrounded by
634/// `Delimiter`s.
635#[derive(Clone)]
636pub struct Group {
637 inner: imp::Group,
638}
639
640/// Describes how a sequence of token trees is delimited.
641#[derive(Copy, Clone, Debug, Eq, PartialEq)]
642pub enum Delimiter {
643 /// `( ... )`
644 Parenthesis,
645 /// `{ ... }`
646 Brace,
647 /// `[ ... ]`
648 Bracket,
649 /// `∅ ... ∅`
650 ///
651 /// An invisible delimiter, that may, for example, appear around tokens
652 /// coming from a "macro variable" `$var`. It is important to preserve
653 /// operator priorities in cases like `$var * 3` where `$var` is `1 + 2`.
654 /// Invisible delimiters may not survive roundtrip of a token stream through
655 /// a string.
656 ///
657 /// <div class="warning">
658 ///
659 /// Note: rustc currently can ignore the grouping of tokens delimited by `None` in the output
660 /// of a proc_macro. Only `None`-delimited groups created by a macro_rules macro in the input
661 /// of a proc_macro macro are preserved, and only in very specific circumstances.
662 /// Any `None`-delimited groups (re)created by a proc_macro will therefore not preserve
663 /// operator priorities as indicated above. The other `Delimiter` variants should be used
664 /// instead in this context. This is a rustc bug. For details, see
665 /// [rust-lang/rust#67062](https://github.com/rust-lang/rust/issues/67062).
666 ///
667 /// </div>
668 None,
669}
670
671impl Group {
672 fn _new(inner: imp::Group) -> Self {
673 Group { inner }
674 }
675
676 fn _new_fallback(inner: fallback::Group) -> Self {
677 Group {
678 inner: imp::Group::from(inner),
679 }
680 }
681
682 /// Creates a new `Group` with the given delimiter and token stream.
683 ///
684 /// This constructor will set the span for this group to
685 /// `Span::call_site()`. To change the span you can use the `set_span`
686 /// method below.
687 pub fn new(delimiter: Delimiter, stream: TokenStream) -> Self {
688 Group {
689 inner: imp::Group::new(delimiter, stream.inner),
690 }
691 }
692
693 /// Returns the punctuation used as the delimiter for this group: a set of
694 /// parentheses, square brackets, or curly braces.
695 pub fn delimiter(&self) -> Delimiter {
696 self.inner.delimiter()
697 }
698
699 /// Returns the `TokenStream` of tokens that are delimited in this `Group`.
700 ///
701 /// Note that the returned token stream does not include the delimiter
702 /// returned above.
703 pub fn stream(&self) -> TokenStream {
704 TokenStream::_new(self.inner.stream())
705 }
706
707 /// Returns the span for the delimiters of this token stream, spanning the
708 /// entire `Group`.
709 ///
710 /// ```text
711 /// pub fn span(&self) -> Span {
712 /// ^^^^^^^
713 /// ```
714 pub fn span(&self) -> Span {
715 Span::_new(self.inner.span())
716 }
717
718 /// Returns the span pointing to the opening delimiter of this group.
719 ///
720 /// ```text
721 /// pub fn span_open(&self) -> Span {
722 /// ^
723 /// ```
724 pub fn span_open(&self) -> Span {
725 Span::_new(self.inner.span_open())
726 }
727
728 /// Returns the span pointing to the closing delimiter of this group.
729 ///
730 /// ```text
731 /// pub fn span_close(&self) -> Span {
732 /// ^
733 /// ```
734 pub fn span_close(&self) -> Span {
735 Span::_new(self.inner.span_close())
736 }
737
738 /// Returns an object that holds this group's `span_open()` and
739 /// `span_close()` together (in a more compact representation than holding
740 /// those 2 spans individually).
741 pub fn delim_span(&self) -> DelimSpan {
742 DelimSpan::new(&self.inner)
743 }
744
745 /// Configures the span for this `Group`'s delimiters, but not its internal
746 /// tokens.
747 ///
748 /// This method will **not** set the span of all the internal tokens spanned
749 /// by this group, but rather it will only set the span of the delimiter
750 /// tokens at the level of the `Group`.
751 pub fn set_span(&mut self, span: Span) {
752 self.inner.set_span(span.inner);
753 }
754}
755
756/// Prints the group as a string that should be losslessly convertible back
757/// into the same group (modulo spans), except for possibly `TokenTree::Group`s
758/// with `Delimiter::None` delimiters.
759impl Display for Group {
760 fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
761 Display::fmt(&self.inner, f:formatter)
762 }
763}
764
765impl Debug for Group {
766 fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
767 Debug::fmt(&self.inner, f:formatter)
768 }
769}
770
771/// A `Punct` is a single punctuation character like `+`, `-` or `#`.
772///
773/// Multicharacter operators like `+=` are represented as two instances of
774/// `Punct` with different forms of `Spacing` returned.
775#[derive(Clone)]
776pub struct Punct {
777 ch: char,
778 spacing: Spacing,
779 span: Span,
780}
781
782/// Whether a `Punct` is followed immediately by another `Punct` or followed by
783/// another token or whitespace.
784#[derive(Copy, Clone, Debug, Eq, PartialEq)]
785pub enum Spacing {
786 /// E.g. `+` is `Alone` in `+ =`, `+ident` or `+()`.
787 Alone,
788 /// E.g. `+` is `Joint` in `+=` or `'` is `Joint` in `'#`.
789 ///
790 /// Additionally, single quote `'` can join with identifiers to form
791 /// lifetimes `'ident`.
792 Joint,
793}
794
795impl Punct {
796 /// Creates a new `Punct` from the given character and spacing.
797 ///
798 /// The `ch` argument must be a valid punctuation character permitted by the
799 /// language, otherwise the function will panic.
800 ///
801 /// The returned `Punct` will have the default span of `Span::call_site()`
802 /// which can be further configured with the `set_span` method below.
803 pub fn new(ch: char, spacing: Spacing) -> Self {
804 if let '!' | '#' | '$' | '%' | '&' | '\'' | '*' | '+' | ',' | '-' | '.' | '/' | ':' | ';'
805 | '<' | '=' | '>' | '?' | '@' | '^' | '|' | '~' = ch
806 {
807 Punct {
808 ch,
809 spacing,
810 span: Span::call_site(),
811 }
812 } else {
813 panic!("unsupported proc macro punctuation character {:?}", ch);
814 }
815 }
816
817 /// Returns the value of this punctuation character as `char`.
818 pub fn as_char(&self) -> char {
819 self.ch
820 }
821
822 /// Returns the spacing of this punctuation character, indicating whether
823 /// it's immediately followed by another `Punct` in the token stream, so
824 /// they can potentially be combined into a multicharacter operator
825 /// (`Joint`), or it's followed by some other token or whitespace (`Alone`)
826 /// so the operator has certainly ended.
827 pub fn spacing(&self) -> Spacing {
828 self.spacing
829 }
830
831 /// Returns the span for this punctuation character.
832 pub fn span(&self) -> Span {
833 self.span
834 }
835
836 /// Configure the span for this punctuation character.
837 pub fn set_span(&mut self, span: Span) {
838 self.span = span;
839 }
840}
841
842/// Prints the punctuation character as a string that should be losslessly
843/// convertible back into the same character.
844impl Display for Punct {
845 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
846 Display::fmt(&self.ch, f)
847 }
848}
849
850impl Debug for Punct {
851 fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
852 let mut debug: DebugStruct<'_, '_> = fmt.debug_struct(name:"Punct");
853 debug.field(name:"char", &self.ch);
854 debug.field(name:"spacing", &self.spacing);
855 imp::debug_span_field_if_nontrivial(&mut debug, self.span.inner);
856 debug.finish()
857 }
858}
859
860/// A word of Rust code, which may be a keyword or legal variable name.
861///
862/// An identifier consists of at least one Unicode code point, the first of
863/// which has the XID_Start property and the rest of which have the XID_Continue
864/// property.
865///
866/// - The empty string is not an identifier. Use `Option<Ident>`.
867/// - A lifetime is not an identifier. Use `syn::Lifetime` instead.
868///
869/// An identifier constructed with `Ident::new` is permitted to be a Rust
870/// keyword, though parsing one through its [`Parse`] implementation rejects
871/// Rust keywords. Use `input.call(Ident::parse_any)` when parsing to match the
872/// behaviour of `Ident::new`.
873///
874/// [`Parse`]: https://docs.rs/syn/2.0/syn/parse/trait.Parse.html
875///
876/// # Examples
877///
878/// A new ident can be created from a string using the `Ident::new` function.
879/// A span must be provided explicitly which governs the name resolution
880/// behavior of the resulting identifier.
881///
882/// ```
883/// use proc_macro2::{Ident, Span};
884///
885/// fn main() {
886/// let call_ident = Ident::new("calligraphy", Span::call_site());
887///
888/// println!("{}", call_ident);
889/// }
890/// ```
891///
892/// An ident can be interpolated into a token stream using the `quote!` macro.
893///
894/// ```
895/// use proc_macro2::{Ident, Span};
896/// use quote::quote;
897///
898/// fn main() {
899/// let ident = Ident::new("demo", Span::call_site());
900///
901/// // Create a variable binding whose name is this ident.
902/// let expanded = quote! { let #ident = 10; };
903///
904/// // Create a variable binding with a slightly different name.
905/// let temp_ident = Ident::new(&format!("new_{}", ident), Span::call_site());
906/// let expanded = quote! { let #temp_ident = 10; };
907/// }
908/// ```
909///
910/// A string representation of the ident is available through the `to_string()`
911/// method.
912///
913/// ```
914/// # use proc_macro2::{Ident, Span};
915/// #
916/// # let ident = Ident::new("another_identifier", Span::call_site());
917/// #
918/// // Examine the ident as a string.
919/// let ident_string = ident.to_string();
920/// if ident_string.len() > 60 {
921/// println!("Very long identifier: {}", ident_string)
922/// }
923/// ```
924#[derive(Clone)]
925pub struct Ident {
926 inner: imp::Ident,
927 _marker: ProcMacroAutoTraits,
928}
929
930impl Ident {
931 fn _new(inner: imp::Ident) -> Self {
932 Ident {
933 inner,
934 _marker: MARKER,
935 }
936 }
937
938 fn _new_fallback(inner: fallback::Ident) -> Self {
939 Ident {
940 inner: imp::Ident::from(inner),
941 _marker: MARKER,
942 }
943 }
944
945 /// Creates a new `Ident` with the given `string` as well as the specified
946 /// `span`.
947 ///
948 /// The `string` argument must be a valid identifier permitted by the
949 /// language, otherwise the function will panic.
950 ///
951 /// Note that `span`, currently in rustc, configures the hygiene information
952 /// for this identifier.
953 ///
954 /// As of this time `Span::call_site()` explicitly opts-in to "call-site"
955 /// hygiene meaning that identifiers created with this span will be resolved
956 /// as if they were written directly at the location of the macro call, and
957 /// other code at the macro call site will be able to refer to them as well.
958 ///
959 /// Later spans like `Span::def_site()` will allow to opt-in to
960 /// "definition-site" hygiene meaning that identifiers created with this
961 /// span will be resolved at the location of the macro definition and other
962 /// code at the macro call site will not be able to refer to them.
963 ///
964 /// Due to the current importance of hygiene this constructor, unlike other
965 /// tokens, requires a `Span` to be specified at construction.
966 ///
967 /// # Panics
968 ///
969 /// Panics if the input string is neither a keyword nor a legal variable
970 /// name. If you are not sure whether the string contains an identifier and
971 /// need to handle an error case, use
972 /// <a href="https://docs.rs/syn/2.0/syn/fn.parse_str.html"><code
973 /// style="padding-right:0;">syn::parse_str</code></a><code
974 /// style="padding-left:0;">::&lt;Ident&gt;</code>
975 /// rather than `Ident::new`.
976 #[track_caller]
977 pub fn new(string: &str, span: Span) -> Self {
978 Ident::_new(imp::Ident::new_checked(string, span.inner))
979 }
980
981 /// Same as `Ident::new`, but creates a raw identifier (`r#ident`). The
982 /// `string` argument must be a valid identifier permitted by the language
983 /// (including keywords, e.g. `fn`). Keywords which are usable in path
984 /// segments (e.g. `self`, `super`) are not supported, and will cause a
985 /// panic.
986 #[track_caller]
987 pub fn new_raw(string: &str, span: Span) -> Self {
988 Ident::_new(imp::Ident::new_raw_checked(string, span.inner))
989 }
990
991 /// Returns the span of this `Ident`.
992 pub fn span(&self) -> Span {
993 Span::_new(self.inner.span())
994 }
995
996 /// Configures the span of this `Ident`, possibly changing its hygiene
997 /// context.
998 pub fn set_span(&mut self, span: Span) {
999 self.inner.set_span(span.inner);
1000 }
1001}
1002
1003impl PartialEq for Ident {
1004 fn eq(&self, other: &Ident) -> bool {
1005 self.inner == other.inner
1006 }
1007}
1008
1009impl<T> PartialEq<T> for Ident
1010where
1011 T: ?Sized + AsRef<str>,
1012{
1013 fn eq(&self, other: &T) -> bool {
1014 self.inner == other
1015 }
1016}
1017
1018impl Eq for Ident {}
1019
1020impl PartialOrd for Ident {
1021 fn partial_cmp(&self, other: &Ident) -> Option<Ordering> {
1022 Some(self.cmp(other))
1023 }
1024}
1025
1026impl Ord for Ident {
1027 fn cmp(&self, other: &Ident) -> Ordering {
1028 self.to_string().cmp(&other.to_string())
1029 }
1030}
1031
1032impl Hash for Ident {
1033 fn hash<H: Hasher>(&self, hasher: &mut H) {
1034 self.to_string().hash(state:hasher);
1035 }
1036}
1037
1038/// Prints the identifier as a string that should be losslessly convertible back
1039/// into the same identifier.
1040impl Display for Ident {
1041 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1042 Display::fmt(&self.inner, f)
1043 }
1044}
1045
1046impl Debug for Ident {
1047 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1048 Debug::fmt(&self.inner, f)
1049 }
1050}
1051
1052/// A literal string (`"hello"`), byte string (`b"hello"`), character (`'a'`),
1053/// byte character (`b'a'`), an integer or floating point number with or without
1054/// a suffix (`1`, `1u8`, `2.3`, `2.3f32`).
1055///
1056/// Boolean literals like `true` and `false` do not belong here, they are
1057/// `Ident`s.
1058#[derive(Clone)]
1059pub struct Literal {
1060 inner: imp::Literal,
1061 _marker: ProcMacroAutoTraits,
1062}
1063
1064macro_rules! suffixed_int_literals {
1065 ($($name:ident => $kind:ident,)*) => ($(
1066 /// Creates a new suffixed integer literal with the specified value.
1067 ///
1068 /// This function will create an integer like `1u32` where the integer
1069 /// value specified is the first part of the token and the integral is
1070 /// also suffixed at the end. Literals created from negative numbers may
1071 /// not survive roundtrips through `TokenStream` or strings and may be
1072 /// broken into two tokens (`-` and positive literal).
1073 ///
1074 /// Literals created through this method have the `Span::call_site()`
1075 /// span by default, which can be configured with the `set_span` method
1076 /// below.
1077 pub fn $name(n: $kind) -> Literal {
1078 Literal::_new(imp::Literal::$name(n))
1079 }
1080 )*)
1081}
1082
1083macro_rules! unsuffixed_int_literals {
1084 ($($name:ident => $kind:ident,)*) => ($(
1085 /// Creates a new unsuffixed integer literal with the specified value.
1086 ///
1087 /// This function will create an integer like `1` where the integer
1088 /// value specified is the first part of the token. No suffix is
1089 /// specified on this token, meaning that invocations like
1090 /// `Literal::i8_unsuffixed(1)` are equivalent to
1091 /// `Literal::u32_unsuffixed(1)`. Literals created from negative numbers
1092 /// may not survive roundtrips through `TokenStream` or strings and may
1093 /// be broken into two tokens (`-` and positive literal).
1094 ///
1095 /// Literals created through this method have the `Span::call_site()`
1096 /// span by default, which can be configured with the `set_span` method
1097 /// below.
1098 pub fn $name(n: $kind) -> Literal {
1099 Literal::_new(imp::Literal::$name(n))
1100 }
1101 )*)
1102}
1103
1104impl Literal {
1105 fn _new(inner: imp::Literal) -> Self {
1106 Literal {
1107 inner,
1108 _marker: MARKER,
1109 }
1110 }
1111
1112 fn _new_fallback(inner: fallback::Literal) -> Self {
1113 Literal {
1114 inner: imp::Literal::from(inner),
1115 _marker: MARKER,
1116 }
1117 }
1118
1119 suffixed_int_literals! {
1120 u8_suffixed => u8,
1121 u16_suffixed => u16,
1122 u32_suffixed => u32,
1123 u64_suffixed => u64,
1124 u128_suffixed => u128,
1125 usize_suffixed => usize,
1126 i8_suffixed => i8,
1127 i16_suffixed => i16,
1128 i32_suffixed => i32,
1129 i64_suffixed => i64,
1130 i128_suffixed => i128,
1131 isize_suffixed => isize,
1132 }
1133
1134 unsuffixed_int_literals! {
1135 u8_unsuffixed => u8,
1136 u16_unsuffixed => u16,
1137 u32_unsuffixed => u32,
1138 u64_unsuffixed => u64,
1139 u128_unsuffixed => u128,
1140 usize_unsuffixed => usize,
1141 i8_unsuffixed => i8,
1142 i16_unsuffixed => i16,
1143 i32_unsuffixed => i32,
1144 i64_unsuffixed => i64,
1145 i128_unsuffixed => i128,
1146 isize_unsuffixed => isize,
1147 }
1148
1149 /// Creates a new unsuffixed floating-point literal.
1150 ///
1151 /// This constructor is similar to those like `Literal::i8_unsuffixed` where
1152 /// the float's value is emitted directly into the token but no suffix is
1153 /// used, so it may be inferred to be a `f64` later in the compiler.
1154 /// Literals created from negative numbers may not survive round-trips
1155 /// through `TokenStream` or strings and may be broken into two tokens (`-`
1156 /// and positive literal).
1157 ///
1158 /// # Panics
1159 ///
1160 /// This function requires that the specified float is finite, for example
1161 /// if it is infinity or NaN this function will panic.
1162 pub fn f64_unsuffixed(f: f64) -> Literal {
1163 assert!(f.is_finite());
1164 Literal::_new(imp::Literal::f64_unsuffixed(f))
1165 }
1166
1167 /// Creates a new suffixed floating-point literal.
1168 ///
1169 /// This constructor will create a literal like `1.0f64` where the value
1170 /// specified is the preceding part of the token and `f64` is the suffix of
1171 /// the token. This token will always be inferred to be an `f64` in the
1172 /// compiler. Literals created from negative numbers may not survive
1173 /// round-trips through `TokenStream` or strings and may be broken into two
1174 /// tokens (`-` and positive literal).
1175 ///
1176 /// # Panics
1177 ///
1178 /// This function requires that the specified float is finite, for example
1179 /// if it is infinity or NaN this function will panic.
1180 pub fn f64_suffixed(f: f64) -> Literal {
1181 assert!(f.is_finite());
1182 Literal::_new(imp::Literal::f64_suffixed(f))
1183 }
1184
1185 /// Creates a new unsuffixed floating-point literal.
1186 ///
1187 /// This constructor is similar to those like `Literal::i8_unsuffixed` where
1188 /// the float's value is emitted directly into the token but no suffix is
1189 /// used, so it may be inferred to be a `f64` later in the compiler.
1190 /// Literals created from negative numbers may not survive round-trips
1191 /// through `TokenStream` or strings and may be broken into two tokens (`-`
1192 /// and positive literal).
1193 ///
1194 /// # Panics
1195 ///
1196 /// This function requires that the specified float is finite, for example
1197 /// if it is infinity or NaN this function will panic.
1198 pub fn f32_unsuffixed(f: f32) -> Literal {
1199 assert!(f.is_finite());
1200 Literal::_new(imp::Literal::f32_unsuffixed(f))
1201 }
1202
1203 /// Creates a new suffixed floating-point literal.
1204 ///
1205 /// This constructor will create a literal like `1.0f32` where the value
1206 /// specified is the preceding part of the token and `f32` is the suffix of
1207 /// the token. This token will always be inferred to be an `f32` in the
1208 /// compiler. Literals created from negative numbers may not survive
1209 /// round-trips through `TokenStream` or strings and may be broken into two
1210 /// tokens (`-` and positive literal).
1211 ///
1212 /// # Panics
1213 ///
1214 /// This function requires that the specified float is finite, for example
1215 /// if it is infinity or NaN this function will panic.
1216 pub fn f32_suffixed(f: f32) -> Literal {
1217 assert!(f.is_finite());
1218 Literal::_new(imp::Literal::f32_suffixed(f))
1219 }
1220
1221 /// String literal.
1222 pub fn string(string: &str) -> Literal {
1223 Literal::_new(imp::Literal::string(string))
1224 }
1225
1226 /// Character literal.
1227 pub fn character(ch: char) -> Literal {
1228 Literal::_new(imp::Literal::character(ch))
1229 }
1230
1231 /// Byte character literal.
1232 pub fn byte_character(byte: u8) -> Literal {
1233 Literal::_new(imp::Literal::byte_character(byte))
1234 }
1235
1236 /// Byte string literal.
1237 pub fn byte_string(bytes: &[u8]) -> Literal {
1238 Literal::_new(imp::Literal::byte_string(bytes))
1239 }
1240
1241 /// C string literal.
1242 pub fn c_string(string: &CStr) -> Literal {
1243 Literal::_new(imp::Literal::c_string(string))
1244 }
1245
1246 /// Returns the span encompassing this literal.
1247 pub fn span(&self) -> Span {
1248 Span::_new(self.inner.span())
1249 }
1250
1251 /// Configures the span associated for this literal.
1252 pub fn set_span(&mut self, span: Span) {
1253 self.inner.set_span(span.inner);
1254 }
1255
1256 /// Returns a `Span` that is a subset of `self.span()` containing only
1257 /// the source bytes in range `range`. Returns `None` if the would-be
1258 /// trimmed span is outside the bounds of `self`.
1259 ///
1260 /// Warning: the underlying [`proc_macro::Literal::subspan`] method is
1261 /// nightly-only. When called from within a procedural macro not using a
1262 /// nightly compiler, this method will always return `None`.
1263 pub fn subspan<R: RangeBounds<usize>>(&self, range: R) -> Option<Span> {
1264 self.inner.subspan(range).map(Span::_new)
1265 }
1266
1267 // Intended for the `quote!` macro to use when constructing a proc-macro2
1268 // token out of a macro_rules $:literal token, which is already known to be
1269 // a valid literal. This avoids reparsing/validating the literal's string
1270 // representation. This is not public API other than for quote.
1271 #[doc(hidden)]
1272 pub unsafe fn from_str_unchecked(repr: &str) -> Self {
1273 Literal::_new(unsafe { imp::Literal::from_str_unchecked(repr) })
1274 }
1275}
1276
1277impl FromStr for Literal {
1278 type Err = LexError;
1279
1280 fn from_str(repr: &str) -> Result<Self, LexError> {
1281 match imp::Literal::from_str_checked(repr) {
1282 Ok(lit: Literal) => Ok(Literal::_new(inner:lit)),
1283 Err(lex: LexError) => Err(LexError {
1284 inner: lex,
1285 _marker: MARKER,
1286 }),
1287 }
1288 }
1289}
1290
1291impl Debug for Literal {
1292 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1293 Debug::fmt(&self.inner, f)
1294 }
1295}
1296
1297impl Display for Literal {
1298 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1299 Display::fmt(&self.inner, f)
1300 }
1301}
1302
1303/// Public implementation details for the `TokenStream` type, such as iterators.
1304pub mod token_stream {
1305 use crate::marker::{ProcMacroAutoTraits, MARKER};
1306 use crate::{imp, TokenTree};
1307 use core::fmt::{self, Debug};
1308
1309 pub use crate::TokenStream;
1310
1311 /// An iterator over `TokenStream`'s `TokenTree`s.
1312 ///
1313 /// The iteration is "shallow", e.g. the iterator doesn't recurse into
1314 /// delimited groups, and returns whole groups as token trees.
1315 #[derive(Clone)]
1316 pub struct IntoIter {
1317 inner: imp::TokenTreeIter,
1318 _marker: ProcMacroAutoTraits,
1319 }
1320
1321 impl Iterator for IntoIter {
1322 type Item = TokenTree;
1323
1324 fn next(&mut self) -> Option<TokenTree> {
1325 self.inner.next()
1326 }
1327
1328 fn size_hint(&self) -> (usize, Option<usize>) {
1329 self.inner.size_hint()
1330 }
1331 }
1332
1333 impl Debug for IntoIter {
1334 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1335 f.write_str("TokenStream ")?;
1336 f.debug_list().entries(self.clone()).finish()
1337 }
1338 }
1339
1340 impl IntoIterator for TokenStream {
1341 type Item = TokenTree;
1342 type IntoIter = IntoIter;
1343
1344 fn into_iter(self) -> IntoIter {
1345 IntoIter {
1346 inner: self.inner.into_iter(),
1347 _marker: MARKER,
1348 }
1349 }
1350 }
1351}
1352