proc_macro2/lib.rs
1//! A wrapper around the procedural macro API of the compiler's [`proc_macro`]
2//! crate. This library serves two purposes:
3//!
4//! [`proc_macro`]: https://doc.rust-lang.org/proc_macro/
5//!
6//! - **Bring proc-macro-like functionality to other contexts like build.rs and
7//! main.rs.** Types from `proc_macro` are entirely specific to procedural
8//! macros and cannot ever exist in code outside of a procedural macro.
9//! Meanwhile `proc_macro2` types may exist anywhere including non-macro code.
10//! By developing foundational libraries like [syn] and [quote] against
11//! `proc_macro2` rather than `proc_macro`, the procedural macro ecosystem
12//! becomes easily applicable to many other use cases and we avoid
13//! reimplementing non-macro equivalents of those libraries.
14//!
15//! - **Make procedural macros unit testable.** As a consequence of being
16//! specific to procedural macros, nothing that uses `proc_macro` can be
17//! executed from a unit test. In order for helper libraries or components of
18//! a macro to be testable in isolation, they must be implemented using
19//! `proc_macro2`.
20//!
21//! [syn]: https://github.com/dtolnay/syn
22//! [quote]: https://github.com/dtolnay/quote
23//!
24//! # Usage
25//!
26//! The skeleton of a typical procedural macro typically looks like this:
27//!
28//! ```
29//! extern crate proc_macro;
30//!
31//! # const IGNORE: &str = stringify! {
32//! #[proc_macro_derive(MyDerive)]
33//! # };
34//! # #[cfg(wrap_proc_macro)]
35//! pub fn my_derive(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
36//! let input = proc_macro2::TokenStream::from(input);
37//!
38//! let output: proc_macro2::TokenStream = {
39//! /* transform input */
40//! # input
41//! };
42//!
43//! proc_macro::TokenStream::from(output)
44//! }
45//! ```
46//!
47//! If parsing with [Syn], you'll use [`parse_macro_input!`] instead to
48//! propagate parse errors correctly back to the compiler when parsing fails.
49//!
50//! [`parse_macro_input!`]: https://docs.rs/syn/1.0/syn/macro.parse_macro_input.html
51//!
52//! # Unstable features
53//!
54//! The default feature set of proc-macro2 tracks the most recent stable
55//! compiler API. Functionality in `proc_macro` that is not yet stable is not
56//! exposed by proc-macro2 by default.
57//!
58//! To opt into the additional APIs available in the most recent nightly
59//! compiler, the `procmacro2_semver_exempt` config flag must be passed to
60//! rustc. We will polyfill those nightly-only APIs back to Rust 1.31.0. As
61//! these are unstable APIs that track the nightly compiler, minor versions of
62//! proc-macro2 may make breaking changes to them at any time.
63//!
64//! ```sh
65//! RUSTFLAGS='--cfg procmacro2_semver_exempt' cargo build
66//! ```
67//!
68//! Note that this must not only be done for your crate, but for any crate that
69//! depends on your crate. This infectious nature is intentional, as it serves
70//! as a reminder that you are outside of the normal semver guarantees.
71//!
72//! Semver exempt methods are marked as such in the proc-macro2 documentation.
73//!
74//! # Thread-Safety
75//!
76//! Most types in this crate are `!Sync` because the underlying compiler
77//! types make use of thread-local memory, meaning they cannot be accessed from
78//! a different thread.
79
80// Proc-macro2 types in rustdoc of other crates get linked to here.
81#![doc(html_root_url = "https://docs.rs/proc-macro2/1.0.6")]
82#![cfg_attr(any(proc_macro_span, super_unstable), feature(proc_macro_span))]
83#![cfg_attr(super_unstable, feature(proc_macro_raw_ident, proc_macro_def_site))]
84
85#[cfg(use_proc_macro)]
86extern crate proc_macro;
87
88use std::cmp::Ordering;
89use std::fmt;
90use std::hash::{Hash, Hasher};
91use std::iter::FromIterator;
92use std::marker;
93use std::ops::RangeBounds;
94#[cfg(procmacro2_semver_exempt)]
95use std::path::PathBuf;
96use std::rc::Rc;
97use std::str::FromStr;
98
99#[macro_use]
100mod strnom;
101mod fallback;
102
103#[cfg(not(wrap_proc_macro))]
104use crate::fallback as imp;
105#[path = "wrapper.rs"]
106#[cfg(wrap_proc_macro)]
107mod imp;
108
109/// An abstract stream of tokens, or more concretely a sequence of token trees.
110///
111/// This type provides interfaces for iterating over token trees and for
112/// collecting token trees into one stream.
113///
114/// Token stream is both the input and output of `#[proc_macro]`,
115/// `#[proc_macro_attribute]` and `#[proc_macro_derive]` definitions.
116#[derive(Clone)]
117pub struct TokenStream {
118 inner: imp::TokenStream,
119 _marker: marker::PhantomData<Rc<()>>,
120}
121
122/// Error returned from `TokenStream::from_str`.
123pub struct LexError {
124 inner: imp::LexError,
125 _marker: marker::PhantomData<Rc<()>>,
126}
127
128impl TokenStream {
129 fn _new(inner: imp::TokenStream) -> TokenStream {
130 TokenStream {
131 inner,
132 _marker: marker::PhantomData,
133 }
134 }
135
136 fn _new_stable(inner: fallback::TokenStream) -> TokenStream {
137 TokenStream {
138 inner: inner.into(),
139 _marker: marker::PhantomData,
140 }
141 }
142
143 /// Returns an empty `TokenStream` containing no token trees.
144 pub fn new() -> TokenStream {
145 TokenStream::_new(imp::TokenStream::new())
146 }
147
148 /// Checks if this `TokenStream` is empty.
149 pub fn is_empty(&self) -> bool {
150 self.inner.is_empty()
151 }
152}
153
154/// `TokenStream::default()` returns an empty stream,
155/// i.e. this is equivalent with `TokenStream::new()`.
156impl Default for TokenStream {
157 fn default() -> Self {
158 TokenStream::new()
159 }
160}
161
162/// Attempts to break the string into tokens and parse those tokens into a token
163/// stream.
164///
165/// May fail for a number of reasons, for example, if the string contains
166/// unbalanced delimiters or characters not existing in the language.
167///
168/// NOTE: Some errors may cause panics instead of returning `LexError`. We
169/// reserve the right to change these errors into `LexError`s later.
170impl FromStr for TokenStream {
171 type Err = LexError;
172
173 fn from_str(src: &str) -> Result<TokenStream, LexError> {
174 let e = src.parse().map_err(|e| LexError {
175 inner: e,
176 _marker: marker::PhantomData,
177 })?;
178 Ok(TokenStream::_new(e))
179 }
180}
181
182#[cfg(use_proc_macro)]
183impl From<proc_macro::TokenStream> for TokenStream {
184 fn from(inner: proc_macro::TokenStream) -> TokenStream {
185 TokenStream::_new(inner.into())
186 }
187}
188
189#[cfg(use_proc_macro)]
190impl From<TokenStream> for proc_macro::TokenStream {
191 fn from(inner: TokenStream) -> proc_macro::TokenStream {
192 inner.inner.into()
193 }
194}
195
196impl From<TokenTree> for TokenStream {
197 fn from(token: TokenTree) -> Self {
198 TokenStream::_new(imp::TokenStream::from(token))
199 }
200}
201
202impl Extend<TokenTree> for TokenStream {
203 fn extend<I: IntoIterator<Item = TokenTree>>(&mut self, streams: I) {
204 self.inner.extend(streams)
205 }
206}
207
208impl Extend<TokenStream> for TokenStream {
209 fn extend<I: IntoIterator<Item = TokenStream>>(&mut self, streams: I) {
210 self.inner
211 .extend(streams.into_iter().map(|stream| stream.inner))
212 }
213}
214
215/// Collects a number of token trees into a single stream.
216impl FromIterator<TokenTree> for TokenStream {
217 fn from_iter<I: IntoIterator<Item = TokenTree>>(streams: I) -> Self {
218 TokenStream::_new(streams.into_iter().collect())
219 }
220}
221impl FromIterator<TokenStream> for TokenStream {
222 fn from_iter<I: IntoIterator<Item = TokenStream>>(streams: I) -> Self {
223 TokenStream::_new(streams.into_iter().map(|i| i.inner).collect())
224 }
225}
226
227/// Prints the token stream as a string that is supposed to be losslessly
228/// convertible back into the same token stream (modulo spans), except for
229/// possibly `TokenTree::Group`s with `Delimiter::None` delimiters and negative
230/// numeric literals.
231impl fmt::Display for TokenStream {
232 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
233 self.inner.fmt(f)
234 }
235}
236
237/// Prints token in a form convenient for debugging.
238impl fmt::Debug for TokenStream {
239 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
240 self.inner.fmt(f)
241 }
242}
243
244impl fmt::Debug for LexError {
245 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
246 self.inner.fmt(f)
247 }
248}
249
250/// The source file of a given `Span`.
251///
252/// This type is semver exempt and not exposed by default.
253#[cfg(procmacro2_semver_exempt)]
254#[derive(Clone, PartialEq, Eq)]
255pub struct SourceFile {
256 inner: imp::SourceFile,
257 _marker: marker::PhantomData<Rc<()>>,
258}
259
260#[cfg(procmacro2_semver_exempt)]
261impl SourceFile {
262 fn _new(inner: imp::SourceFile) -> Self {
263 SourceFile {
264 inner,
265 _marker: marker::PhantomData,
266 }
267 }
268
269 /// Get the path to this source file.
270 ///
271 /// ### Note
272 ///
273 /// If the code span associated with this `SourceFile` was generated by an
274 /// external macro, this may not be an actual path on the filesystem. Use
275 /// [`is_real`] to check.
276 ///
277 /// Also note that even if `is_real` returns `true`, if
278 /// `--remap-path-prefix` was passed on the command line, the path as given
279 /// may not actually be valid.
280 ///
281 /// [`is_real`]: #method.is_real
282 pub fn path(&self) -> PathBuf {
283 self.inner.path()
284 }
285
286 /// Returns `true` if this source file is a real source file, and not
287 /// generated by an external macro's expansion.
288 pub fn is_real(&self) -> bool {
289 self.inner.is_real()
290 }
291}
292
293#[cfg(procmacro2_semver_exempt)]
294impl fmt::Debug for SourceFile {
295 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
296 self.inner.fmt(f)
297 }
298}
299
300/// A line-column pair representing the start or end of a `Span`.
301///
302/// This type is semver exempt and not exposed by default.
303#[cfg(span_locations)]
304#[derive(Copy, Clone, Debug, PartialEq, Eq)]
305pub struct LineColumn {
306 /// The 1-indexed line in the source file on which the span starts or ends
307 /// (inclusive).
308 pub line: usize,
309 /// The 0-indexed column (in UTF-8 characters) in the source file on which
310 /// the span starts or ends (inclusive).
311 pub column: usize,
312}
313
314/// A region of source code, along with macro expansion information.
315#[derive(Copy, Clone)]
316pub struct Span {
317 inner: imp::Span,
318 _marker: marker::PhantomData<Rc<()>>,
319}
320
321impl Span {
322 fn _new(inner: imp::Span) -> Span {
323 Span {
324 inner,
325 _marker: marker::PhantomData,
326 }
327 }
328
329 fn _new_stable(inner: fallback::Span) -> Span {
330 Span {
331 inner: inner.into(),
332 _marker: marker::PhantomData,
333 }
334 }
335
336 /// The span of the invocation of the current procedural macro.
337 ///
338 /// Identifiers created with this span will be resolved as if they were
339 /// written directly at the macro call location (call-site hygiene) and
340 /// other code at the macro call site will be able to refer to them as well.
341 pub fn call_site() -> Span {
342 Span::_new(imp::Span::call_site())
343 }
344
345 /// A span that resolves at the macro definition site.
346 ///
347 /// This method is semver exempt and not exposed by default.
348 #[cfg(procmacro2_semver_exempt)]
349 pub fn def_site() -> Span {
350 Span::_new(imp::Span::def_site())
351 }
352
353 /// Creates a new span with the same line/column information as `self` but
354 /// that resolves symbols as though it were at `other`.
355 ///
356 /// This method is semver exempt and not exposed by default.
357 #[cfg(procmacro2_semver_exempt)]
358 pub fn resolved_at(&self, other: Span) -> Span {
359 Span::_new(self.inner.resolved_at(other.inner))
360 }
361
362 /// Creates a new span with the same name resolution behavior as `self` but
363 /// with the line/column information of `other`.
364 ///
365 /// This method is semver exempt and not exposed by default.
366 #[cfg(procmacro2_semver_exempt)]
367 pub fn located_at(&self, other: Span) -> Span {
368 Span::_new(self.inner.located_at(other.inner))
369 }
370
371 /// Convert `proc_macro2::Span` to `proc_macro::Span`.
372 ///
373 /// This method is available when building with a nightly compiler, or when
374 /// building with rustc 1.29+ *without* semver exempt features.
375 ///
376 /// # Panics
377 ///
378 /// Panics if called from outside of a procedural macro. Unlike
379 /// `proc_macro2::Span`, the `proc_macro::Span` type can only exist within
380 /// the context of a procedural macro invocation.
381 #[cfg(wrap_proc_macro)]
382 pub fn unwrap(self) -> proc_macro::Span {
383 self.inner.unwrap()
384 }
385
386 // Soft deprecated. Please use Span::unwrap.
387 #[cfg(wrap_proc_macro)]
388 #[doc(hidden)]
389 pub fn unstable(self) -> proc_macro::Span {
390 self.unwrap()
391 }
392
393 /// The original source file into which this span points.
394 ///
395 /// This method is semver exempt and not exposed by default.
396 #[cfg(procmacro2_semver_exempt)]
397 pub fn source_file(&self) -> SourceFile {
398 SourceFile::_new(self.inner.source_file())
399 }
400
401 /// Get the starting line/column in the source file for this span.
402 ///
403 /// This method requires the `"span-locations"` feature to be enabled.
404 #[cfg(span_locations)]
405 pub fn start(&self) -> LineColumn {
406 let imp::LineColumn { line, column } = self.inner.start();
407 LineColumn { line, column }
408 }
409
410 /// Get the ending line/column in the source file for this span.
411 ///
412 /// This method requires the `"span-locations"` feature to be enabled.
413 #[cfg(span_locations)]
414 pub fn end(&self) -> LineColumn {
415 let imp::LineColumn { line, column } = self.inner.end();
416 LineColumn { line, column }
417 }
418
419 /// Create a new span encompassing `self` and `other`.
420 ///
421 /// Returns `None` if `self` and `other` are from different files.
422 ///
423 /// Warning: the underlying [`proc_macro::Span::join`] method is
424 /// nightly-only. When called from within a procedural macro not using a
425 /// nightly compiler, this method will always return `None`.
426 ///
427 /// [`proc_macro::Span::join`]: https://doc.rust-lang.org/proc_macro/struct.Span.html#method.join
428 pub fn join(&self, other: Span) -> Option<Span> {
429 self.inner.join(other.inner).map(Span::_new)
430 }
431
432 /// Compares two spans to see if they're equal.
433 ///
434 /// This method is semver exempt and not exposed by default.
435 #[cfg(procmacro2_semver_exempt)]
436 pub fn eq(&self, other: &Span) -> bool {
437 self.inner.eq(&other.inner)
438 }
439}
440
441/// Prints a span in a form convenient for debugging.
442impl fmt::Debug for Span {
443 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
444 self.inner.fmt(f)
445 }
446}
447
448/// A single token or a delimited sequence of token trees (e.g. `[1, (), ..]`).
449#[derive(Clone)]
450pub enum TokenTree {
451 /// A token stream surrounded by bracket delimiters.
452 Group(Group),
453 /// An identifier.
454 Ident(Ident),
455 /// A single punctuation character (`+`, `,`, `$`, etc.).
456 Punct(Punct),
457 /// A literal character (`'a'`), string (`"hello"`), number (`2.3`), etc.
458 Literal(Literal),
459}
460
461impl TokenTree {
462 /// Returns the span of this tree, delegating to the `span` method of
463 /// the contained token or a delimited stream.
464 pub fn span(&self) -> Span {
465 match *self {
466 TokenTree::Group(ref t) => t.span(),
467 TokenTree::Ident(ref t) => t.span(),
468 TokenTree::Punct(ref t) => t.span(),
469 TokenTree::Literal(ref t) => t.span(),
470 }
471 }
472
473 /// Configures the span for *only this token*.
474 ///
475 /// Note that if this token is a `Group` then this method will not configure
476 /// the span of each of the internal tokens, this will simply delegate to
477 /// the `set_span` method of each variant.
478 pub fn set_span(&mut self, span: Span) {
479 match *self {
480 TokenTree::Group(ref mut t) => t.set_span(span),
481 TokenTree::Ident(ref mut t) => t.set_span(span),
482 TokenTree::Punct(ref mut t) => t.set_span(span),
483 TokenTree::Literal(ref mut t) => t.set_span(span),
484 }
485 }
486}
487
488impl From<Group> for TokenTree {
489 fn from(g: Group) -> TokenTree {
490 TokenTree::Group(g)
491 }
492}
493
494impl From<Ident> for TokenTree {
495 fn from(g: Ident) -> TokenTree {
496 TokenTree::Ident(g)
497 }
498}
499
500impl From<Punct> for TokenTree {
501 fn from(g: Punct) -> TokenTree {
502 TokenTree::Punct(g)
503 }
504}
505
506impl From<Literal> for TokenTree {
507 fn from(g: Literal) -> TokenTree {
508 TokenTree::Literal(g)
509 }
510}
511
512/// Prints the token tree as a string that is supposed to be losslessly
513/// convertible back into the same token tree (modulo spans), except for
514/// possibly `TokenTree::Group`s with `Delimiter::None` delimiters and negative
515/// numeric literals.
516impl fmt::Display for TokenTree {
517 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
518 match *self {
519 TokenTree::Group(ref t) => t.fmt(f),
520 TokenTree::Ident(ref t) => t.fmt(f),
521 TokenTree::Punct(ref t) => t.fmt(f),
522 TokenTree::Literal(ref t) => t.fmt(f),
523 }
524 }
525}
526
527/// Prints token tree in a form convenient for debugging.
528impl fmt::Debug for TokenTree {
529 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
530 // Each of these has the name in the struct type in the derived debug,
531 // so don't bother with an extra layer of indirection
532 match *self {
533 TokenTree::Group(ref t) => t.fmt(f),
534 TokenTree::Ident(ref t) => {
535 let mut debug = f.debug_struct("Ident");
536 debug.field("sym", &format_args!("{}", t));
537 imp::debug_span_field_if_nontrivial(&mut debug, t.span().inner);
538 debug.finish()
539 }
540 TokenTree::Punct(ref t) => t.fmt(f),
541 TokenTree::Literal(ref t) => t.fmt(f),
542 }
543 }
544}
545
546/// A delimited token stream.
547///
548/// A `Group` internally contains a `TokenStream` which is surrounded by
549/// `Delimiter`s.
550#[derive(Clone)]
551pub struct Group {
552 inner: imp::Group,
553}
554
555/// Describes how a sequence of token trees is delimited.
556#[derive(Copy, Clone, Debug, Eq, PartialEq)]
557pub enum Delimiter {
558 /// `( ... )`
559 Parenthesis,
560 /// `{ ... }`
561 Brace,
562 /// `[ ... ]`
563 Bracket,
564 /// `Ø ... Ø`
565 ///
566 /// An implicit delimiter, that may, for example, appear around tokens
567 /// coming from a "macro variable" `$var`. It is important to preserve
568 /// operator priorities in cases like `$var * 3` where `$var` is `1 + 2`.
569 /// Implicit delimiters may not survive roundtrip of a token stream through
570 /// a string.
571 None,
572}
573
574impl Group {
575 fn _new(inner: imp::Group) -> Self {
576 Group { inner }
577 }
578
579 fn _new_stable(inner: fallback::Group) -> Self {
580 Group {
581 inner: inner.into(),
582 }
583 }
584
585 /// Creates a new `Group` with the given delimiter and token stream.
586 ///
587 /// This constructor will set the span for this group to
588 /// `Span::call_site()`. To change the span you can use the `set_span`
589 /// method below.
590 pub fn new(delimiter: Delimiter, stream: TokenStream) -> Group {
591 Group {
592 inner: imp::Group::new(delimiter, stream.inner),
593 }
594 }
595
596 /// Returns the delimiter of this `Group`
597 pub fn delimiter(&self) -> Delimiter {
598 self.inner.delimiter()
599 }
600
601 /// Returns the `TokenStream` of tokens that are delimited in this `Group`.
602 ///
603 /// Note that the returned token stream does not include the delimiter
604 /// returned above.
605 pub fn stream(&self) -> TokenStream {
606 TokenStream::_new(self.inner.stream())
607 }
608
609 /// Returns the span for the delimiters of this token stream, spanning the
610 /// entire `Group`.
611 ///
612 /// ```text
613 /// pub fn span(&self) -> Span {
614 /// ^^^^^^^
615 /// ```
616 pub fn span(&self) -> Span {
617 Span::_new(self.inner.span())
618 }
619
620 /// Returns the span pointing to the opening delimiter of this group.
621 ///
622 /// ```text
623 /// pub fn span_open(&self) -> Span {
624 /// ^
625 /// ```
626 pub fn span_open(&self) -> Span {
627 Span::_new(self.inner.span_open())
628 }
629
630 /// Returns the span pointing to the closing delimiter of this group.
631 ///
632 /// ```text
633 /// pub fn span_close(&self) -> Span {
634 /// ^
635 /// ```
636 pub fn span_close(&self) -> Span {
637 Span::_new(self.inner.span_close())
638 }
639
640 /// Configures the span for this `Group`'s delimiters, but not its internal
641 /// tokens.
642 ///
643 /// This method will **not** set the span of all the internal tokens spanned
644 /// by this group, but rather it will only set the span of the delimiter
645 /// tokens at the level of the `Group`.
646 pub fn set_span(&mut self, span: Span) {
647 self.inner.set_span(span.inner)
648 }
649}
650
651/// Prints the group as a string that should be losslessly convertible back
652/// into the same group (modulo spans), except for possibly `TokenTree::Group`s
653/// with `Delimiter::None` delimiters.
654impl fmt::Display for Group {
655 fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
656 fmt::Display::fmt(&self.inner, formatter)
657 }
658}
659
660impl fmt::Debug for Group {
661 fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
662 fmt::Debug::fmt(&self.inner, formatter)
663 }
664}
665
666/// An `Punct` is an single punctuation character like `+`, `-` or `#`.
667///
668/// Multicharacter operators like `+=` are represented as two instances of
669/// `Punct` with different forms of `Spacing` returned.
670#[derive(Clone)]
671pub struct Punct {
672 op: char,
673 spacing: Spacing,
674 span: Span,
675}
676
677/// Whether an `Punct` is followed immediately by another `Punct` or followed by
678/// another token or whitespace.
679#[derive(Copy, Clone, Debug, Eq, PartialEq)]
680pub enum Spacing {
681 /// E.g. `+` is `Alone` in `+ =`, `+ident` or `+()`.
682 Alone,
683 /// E.g. `+` is `Joint` in `+=` or `'` is `Joint` in `'#`.
684 ///
685 /// Additionally, single quote `'` can join with identifiers to form
686 /// lifetimes `'ident`.
687 Joint,
688}
689
690impl Punct {
691 /// Creates a new `Punct` from the given character and spacing.
692 ///
693 /// The `ch` argument must be a valid punctuation character permitted by the
694 /// language, otherwise the function will panic.
695 ///
696 /// The returned `Punct` will have the default span of `Span::call_site()`
697 /// which can be further configured with the `set_span` method below.
698 pub fn new(op: char, spacing: Spacing) -> Punct {
699 Punct {
700 op,
701 spacing,
702 span: Span::call_site(),
703 }
704 }
705
706 /// Returns the value of this punctuation character as `char`.
707 pub fn as_char(&self) -> char {
708 self.op
709 }
710
711 /// Returns the spacing of this punctuation character, indicating whether
712 /// it's immediately followed by another `Punct` in the token stream, so
713 /// they can potentially be combined into a multicharacter operator
714 /// (`Joint`), or it's followed by some other token or whitespace (`Alone`)
715 /// so the operator has certainly ended.
716 pub fn spacing(&self) -> Spacing {
717 self.spacing
718 }
719
720 /// Returns the span for this punctuation character.
721 pub fn span(&self) -> Span {
722 self.span
723 }
724
725 /// Configure the span for this punctuation character.
726 pub fn set_span(&mut self, span: Span) {
727 self.span = span;
728 }
729}
730
731/// Prints the punctuation character as a string that should be losslessly
732/// convertible back into the same character.
733impl fmt::Display for Punct {
734 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
735 self.op.fmt(f)
736 }
737}
738
739impl fmt::Debug for Punct {
740 fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
741 let mut debug = fmt.debug_struct("Punct");
742 debug.field("op", &self.op);
743 debug.field("spacing", &self.spacing);
744 imp::debug_span_field_if_nontrivial(&mut debug, self.span.inner);
745 debug.finish()
746 }
747}
748
749/// A word of Rust code, which may be a keyword or legal variable name.
750///
751/// An identifier consists of at least one Unicode code point, the first of
752/// which has the XID_Start property and the rest of which have the XID_Continue
753/// property.
754///
755/// - The empty string is not an identifier. Use `Option<Ident>`.
756/// - A lifetime is not an identifier. Use `syn::Lifetime` instead.
757///
758/// An identifier constructed with `Ident::new` is permitted to be a Rust
759/// keyword, though parsing one through its [`Parse`] implementation rejects
760/// Rust keywords. Use `input.call(Ident::parse_any)` when parsing to match the
761/// behaviour of `Ident::new`.
762///
763/// [`Parse`]: https://docs.rs/syn/1.0/syn/parse/trait.Parse.html
764///
765/// # Examples
766///
767/// A new ident can be created from a string using the `Ident::new` function.
768/// A span must be provided explicitly which governs the name resolution
769/// behavior of the resulting identifier.
770///
771/// ```
772/// use proc_macro2::{Ident, Span};
773///
774/// fn main() {
775/// let call_ident = Ident::new("calligraphy", Span::call_site());
776///
777/// println!("{}", call_ident);
778/// }
779/// ```
780///
781/// An ident can be interpolated into a token stream using the `quote!` macro.
782///
783/// ```
784/// use proc_macro2::{Ident, Span};
785/// use quote::quote;
786///
787/// fn main() {
788/// let ident = Ident::new("demo", Span::call_site());
789///
790/// // Create a variable binding whose name is this ident.
791/// let expanded = quote! { let #ident = 10; };
792///
793/// // Create a variable binding with a slightly different name.
794/// let temp_ident = Ident::new(&format!("new_{}", ident), Span::call_site());
795/// let expanded = quote! { let #temp_ident = 10; };
796/// }
797/// ```
798///
799/// A string representation of the ident is available through the `to_string()`
800/// method.
801///
802/// ```
803/// # use proc_macro2::{Ident, Span};
804/// #
805/// # let ident = Ident::new("another_identifier", Span::call_site());
806/// #
807/// // Examine the ident as a string.
808/// let ident_string = ident.to_string();
809/// if ident_string.len() > 60 {
810/// println!("Very long identifier: {}", ident_string)
811/// }
812/// ```
813#[derive(Clone)]
814pub struct Ident {
815 inner: imp::Ident,
816 _marker: marker::PhantomData<Rc<()>>,
817}
818
819impl Ident {
820 fn _new(inner: imp::Ident) -> Ident {
821 Ident {
822 inner,
823 _marker: marker::PhantomData,
824 }
825 }
826
827 /// Creates a new `Ident` with the given `string` as well as the specified
828 /// `span`.
829 ///
830 /// The `string` argument must be a valid identifier permitted by the
831 /// language, otherwise the function will panic.
832 ///
833 /// Note that `span`, currently in rustc, configures the hygiene information
834 /// for this identifier.
835 ///
836 /// As of this time `Span::call_site()` explicitly opts-in to "call-site"
837 /// hygiene meaning that identifiers created with this span will be resolved
838 /// as if they were written directly at the location of the macro call, and
839 /// other code at the macro call site will be able to refer to them as well.
840 ///
841 /// Later spans like `Span::def_site()` will allow to opt-in to
842 /// "definition-site" hygiene meaning that identifiers created with this
843 /// span will be resolved at the location of the macro definition and other
844 /// code at the macro call site will not be able to refer to them.
845 ///
846 /// Due to the current importance of hygiene this constructor, unlike other
847 /// tokens, requires a `Span` to be specified at construction.
848 ///
849 /// # Panics
850 ///
851 /// Panics if the input string is neither a keyword nor a legal variable
852 /// name. If you are not sure whether the string contains an identifier and
853 /// need to handle an error case, use
854 /// <a href="https://docs.rs/syn/1.0/syn/fn.parse_str.html"><code
855 /// style="padding-right:0;">syn::parse_str</code></a><code
856 /// style="padding-left:0;">::<Ident></code>
857 /// rather than `Ident::new`.
858 pub fn new(string: &str, span: Span) -> Ident {
859 Ident::_new(imp::Ident::new(string, span.inner))
860 }
861
862 /// Same as `Ident::new`, but creates a raw identifier (`r#ident`).
863 ///
864 /// This method is semver exempt and not exposed by default.
865 #[cfg(procmacro2_semver_exempt)]
866 pub fn new_raw(string: &str, span: Span) -> Ident {
867 Ident::_new_raw(string, span)
868 }
869
870 fn _new_raw(string: &str, span: Span) -> Ident {
871 Ident::_new(imp::Ident::new_raw(string, span.inner))
872 }
873
874 /// Returns the span of this `Ident`.
875 pub fn span(&self) -> Span {
876 Span::_new(self.inner.span())
877 }
878
879 /// Configures the span of this `Ident`, possibly changing its hygiene
880 /// context.
881 pub fn set_span(&mut self, span: Span) {
882 self.inner.set_span(span.inner);
883 }
884}
885
886impl PartialEq for Ident {
887 fn eq(&self, other: &Ident) -> bool {
888 self.inner == other.inner
889 }
890}
891
892impl<T> PartialEq<T> for Ident
893where
894 T: ?Sized + AsRef<str>,
895{
896 fn eq(&self, other: &T) -> bool {
897 self.inner == other
898 }
899}
900
901impl Eq for Ident {}
902
903impl PartialOrd for Ident {
904 fn partial_cmp(&self, other: &Ident) -> Option<Ordering> {
905 Some(self.cmp(other))
906 }
907}
908
909impl Ord for Ident {
910 fn cmp(&self, other: &Ident) -> Ordering {
911 self.to_string().cmp(&other.to_string())
912 }
913}
914
915impl Hash for Ident {
916 fn hash<H: Hasher>(&self, hasher: &mut H) {
917 self.to_string().hash(hasher)
918 }
919}
920
921/// Prints the identifier as a string that should be losslessly convertible back
922/// into the same identifier.
923impl fmt::Display for Ident {
924 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
925 self.inner.fmt(f)
926 }
927}
928
929impl fmt::Debug for Ident {
930 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
931 self.inner.fmt(f)
932 }
933}
934
935/// A literal string (`"hello"`), byte string (`b"hello"`), character (`'a'`),
936/// byte character (`b'a'`), an integer or floating point number with or without
937/// a suffix (`1`, `1u8`, `2.3`, `2.3f32`).
938///
939/// Boolean literals like `true` and `false` do not belong here, they are
940/// `Ident`s.
941#[derive(Clone)]
942pub struct Literal {
943 inner: imp::Literal,
944 _marker: marker::PhantomData<Rc<()>>,
945}
946
947macro_rules! suffixed_int_literals {
948 ($($name:ident => $kind:ident,)*) => ($(
949 /// Creates a new suffixed integer literal with the specified value.
950 ///
951 /// This function will create an integer like `1u32` where the integer
952 /// value specified is the first part of the token and the integral is
953 /// also suffixed at the end. Literals created from negative numbers may
954 /// not survive rountrips through `TokenStream` or strings and may be
955 /// broken into two tokens (`-` and positive literal).
956 ///
957 /// Literals created through this method have the `Span::call_site()`
958 /// span by default, which can be configured with the `set_span` method
959 /// below.
960 pub fn $name(n: $kind) -> Literal {
961 Literal::_new(imp::Literal::$name(n))
962 }
963 )*)
964}
965
966macro_rules! unsuffixed_int_literals {
967 ($($name:ident => $kind:ident,)*) => ($(
968 /// Creates a new unsuffixed integer literal with the specified value.
969 ///
970 /// This function will create an integer like `1` where the integer
971 /// value specified is the first part of the token. No suffix is
972 /// specified on this token, meaning that invocations like
973 /// `Literal::i8_unsuffixed(1)` are equivalent to
974 /// `Literal::u32_unsuffixed(1)`. Literals created from negative numbers
975 /// may not survive rountrips through `TokenStream` or strings and may
976 /// be broken into two tokens (`-` and positive literal).
977 ///
978 /// Literals created through this method have the `Span::call_site()`
979 /// span by default, which can be configured with the `set_span` method
980 /// below.
981 pub fn $name(n: $kind) -> Literal {
982 Literal::_new(imp::Literal::$name(n))
983 }
984 )*)
985}
986
987impl Literal {
988 fn _new(inner: imp::Literal) -> Literal {
989 Literal {
990 inner,
991 _marker: marker::PhantomData,
992 }
993 }
994
995 fn _new_stable(inner: fallback::Literal) -> Literal {
996 Literal {
997 inner: inner.into(),
998 _marker: marker::PhantomData,
999 }
1000 }
1001
1002 suffixed_int_literals! {
1003 u8_suffixed => u8,
1004 u16_suffixed => u16,
1005 u32_suffixed => u32,
1006 u64_suffixed => u64,
1007 u128_suffixed => u128,
1008 usize_suffixed => usize,
1009 i8_suffixed => i8,
1010 i16_suffixed => i16,
1011 i32_suffixed => i32,
1012 i64_suffixed => i64,
1013 i128_suffixed => i128,
1014 isize_suffixed => isize,
1015 }
1016
1017 unsuffixed_int_literals! {
1018 u8_unsuffixed => u8,
1019 u16_unsuffixed => u16,
1020 u32_unsuffixed => u32,
1021 u64_unsuffixed => u64,
1022 u128_unsuffixed => u128,
1023 usize_unsuffixed => usize,
1024 i8_unsuffixed => i8,
1025 i16_unsuffixed => i16,
1026 i32_unsuffixed => i32,
1027 i64_unsuffixed => i64,
1028 i128_unsuffixed => i128,
1029 isize_unsuffixed => isize,
1030 }
1031
1032 /// Creates a new unsuffixed floating-point literal.
1033 ///
1034 /// This constructor is similar to those like `Literal::i8_unsuffixed` where
1035 /// the float's value is emitted directly into the token but no suffix is
1036 /// used, so it may be inferred to be a `f64` later in the compiler.
1037 /// Literals created from negative numbers may not survive rountrips through
1038 /// `TokenStream` or strings and may be broken into two tokens (`-` and
1039 /// positive literal).
1040 ///
1041 /// # Panics
1042 ///
1043 /// This function requires that the specified float is finite, for example
1044 /// if it is infinity or NaN this function will panic.
1045 pub fn f64_unsuffixed(f: f64) -> Literal {
1046 assert!(f.is_finite());
1047 Literal::_new(imp::Literal::f64_unsuffixed(f))
1048 }
1049
1050 /// Creates a new suffixed floating-point literal.
1051 ///
1052 /// This constructor will create a literal like `1.0f64` where the value
1053 /// specified is the preceding part of the token and `f64` is the suffix of
1054 /// the token. This token will always be inferred to be an `f64` in the
1055 /// compiler. Literals created from negative numbers may not survive
1056 /// rountrips through `TokenStream` or strings and may be broken into two
1057 /// tokens (`-` and positive literal).
1058 ///
1059 /// # Panics
1060 ///
1061 /// This function requires that the specified float is finite, for example
1062 /// if it is infinity or NaN this function will panic.
1063 pub fn f64_suffixed(f: f64) -> Literal {
1064 assert!(f.is_finite());
1065 Literal::_new(imp::Literal::f64_suffixed(f))
1066 }
1067
1068 /// Creates a new unsuffixed floating-point literal.
1069 ///
1070 /// This constructor is similar to those like `Literal::i8_unsuffixed` where
1071 /// the float's value is emitted directly into the token but no suffix is
1072 /// used, so it may be inferred to be a `f64` later in the compiler.
1073 /// Literals created from negative numbers may not survive rountrips through
1074 /// `TokenStream` or strings and may be broken into two tokens (`-` and
1075 /// positive literal).
1076 ///
1077 /// # Panics
1078 ///
1079 /// This function requires that the specified float is finite, for example
1080 /// if it is infinity or NaN this function will panic.
1081 pub fn f32_unsuffixed(f: f32) -> Literal {
1082 assert!(f.is_finite());
1083 Literal::_new(imp::Literal::f32_unsuffixed(f))
1084 }
1085
1086 /// Creates a new suffixed floating-point literal.
1087 ///
1088 /// This constructor will create a literal like `1.0f32` where the value
1089 /// specified is the preceding part of the token and `f32` is the suffix of
1090 /// the token. This token will always be inferred to be an `f32` in the
1091 /// compiler. Literals created from negative numbers may not survive
1092 /// rountrips through `TokenStream` or strings and may be broken into two
1093 /// tokens (`-` and positive literal).
1094 ///
1095 /// # Panics
1096 ///
1097 /// This function requires that the specified float is finite, for example
1098 /// if it is infinity or NaN this function will panic.
1099 pub fn f32_suffixed(f: f32) -> Literal {
1100 assert!(f.is_finite());
1101 Literal::_new(imp::Literal::f32_suffixed(f))
1102 }
1103
1104 /// String literal.
1105 pub fn string(string: &str) -> Literal {
1106 Literal::_new(imp::Literal::string(string))
1107 }
1108
1109 /// Character literal.
1110 pub fn character(ch: char) -> Literal {
1111 Literal::_new(imp::Literal::character(ch))
1112 }
1113
1114 /// Byte string literal.
1115 pub fn byte_string(s: &[u8]) -> Literal {
1116 Literal::_new(imp::Literal::byte_string(s))
1117 }
1118
1119 /// Returns the span encompassing this literal.
1120 pub fn span(&self) -> Span {
1121 Span::_new(self.inner.span())
1122 }
1123
1124 /// Configures the span associated for this literal.
1125 pub fn set_span(&mut self, span: Span) {
1126 self.inner.set_span(span.inner);
1127 }
1128
1129 /// Returns a `Span` that is a subset of `self.span()` containing only
1130 /// the source bytes in range `range`. Returns `None` if the would-be
1131 /// trimmed span is outside the bounds of `self`.
1132 ///
1133 /// Warning: the underlying [`proc_macro::Literal::subspan`] method is
1134 /// nightly-only. When called from within a procedural macro not using a
1135 /// nightly compiler, this method will always return `None`.
1136 ///
1137 /// [`proc_macro::Literal::subspan`]: https://doc.rust-lang.org/proc_macro/struct.Literal.html#method.subspan
1138 pub fn subspan<R: RangeBounds<usize>>(&self, range: R) -> Option<Span> {
1139 self.inner.subspan(range).map(Span::_new)
1140 }
1141}
1142
1143impl fmt::Debug for Literal {
1144 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1145 self.inner.fmt(f)
1146 }
1147}
1148
1149impl fmt::Display for Literal {
1150 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1151 self.inner.fmt(f)
1152 }
1153}
1154
1155/// Public implementation details for the `TokenStream` type, such as iterators.
1156pub mod token_stream {
1157 use std::fmt;
1158 use std::marker;
1159 use std::rc::Rc;
1160
1161 pub use crate::TokenStream;
1162 use crate::{imp, TokenTree};
1163
1164 /// An iterator over `TokenStream`'s `TokenTree`s.
1165 ///
1166 /// The iteration is "shallow", e.g. the iterator doesn't recurse into
1167 /// delimited groups, and returns whole groups as token trees.
1168 #[derive(Clone)]
1169 pub struct IntoIter {
1170 inner: imp::TokenTreeIter,
1171 _marker: marker::PhantomData<Rc<()>>,
1172 }
1173
1174 impl Iterator for IntoIter {
1175 type Item = TokenTree;
1176
1177 fn next(&mut self) -> Option<TokenTree> {
1178 self.inner.next()
1179 }
1180 }
1181
1182 impl fmt::Debug for IntoIter {
1183 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1184 self.inner.fmt(f)
1185 }
1186 }
1187
1188 impl IntoIterator for TokenStream {
1189 type Item = TokenTree;
1190 type IntoIter = IntoIter;
1191
1192 fn into_iter(self) -> IntoIter {
1193 IntoIter {
1194 inner: self.inner.into_iter(),
1195 _marker: marker::PhantomData,
1196 }
1197 }
1198 }
1199}